Li-Wei Ko

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48ranked-venue papers
6as first author
6since 2021 · last 2025
—ORCID · conflict

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 20 · 5 first-author · 1 since 2021Applied, interdisciplinary, general and emerging computing · 18 · 1 first-author · 5 since 2021Systems, architecture and hardware · 7Human-computer interaction and ubiquitous computing · 7 · 2 since 2021Databases, data management, data science and information retrieval · 1Graphics, computer vision, multimedia, augmented reality and games · 1
YearPublicationVenuePosition
2025 Visual Game-Based Upper Limb Ergometer Therapy Associated with EEG Responses in Stroke Rehabilitation
abstract
This longitudinal EEG study demonstrates that integrating interactive visual gaming with conventional upper limb resistance training enhances motor recovery in post-stroke patients compared to traditional rehabilitation alone. The game-based approach resulted in superior behavioral outcomes, with significantly greater improvements in specific muscle groups. Notably, among participants in the game-based group, those who exhibited peripheral motor improvement also showed significantly greater alpha-band suppression in the lesioned motor cortex compared to non-improved individuals. EEG signals were preprocessed using Independent Component Analysis (ICA), and Power Spectral Density (PSD) analysis was performed to evaluate cortical activation during the rehabilitation period. The findings suggest a positive association between motor cortex activation and improvements in muscle strength. This study presents a clinically feasible rehabilitation model that incorporates game-based feedback without modifying standard protocols, supporting its potential as a more interactive and effective approach for early neurorehabilitation.
Chiao-Hsin Chen, Li-Wei Ko, Hsuan Cheng, Yu-Lin Wang, Kai-Chiao Chi, Chih-Chung Wang, Chia-Hsin Chen
CIBCB2
2025 Closed-Loop Brain-Controlled Exoskeleton System with a Hybrid Model for Stroke Rehabilitation
abstract
Stroke (Cerebrovascular Accident, CVA) is one of the diseases with the greatest impact on human health, particularly due to the neurological dysfunctions that often follow, such as upper or lower limb paralysis, foot drop, muscle weakness, and cognitive impairment, which significantly affect patients' daily lives. Existing research indicates that the first three months after a stroke is the "golden period" for treatment, during which rehabilitation training can greatly improve a patient's quality of life and promote neuroplasticity. However, some stroke patients are unable to engage in active rehabilitation training due to physical limitations and can only rely on passive rehabilitation methods. To address this issue, this study proposes a closed-loop brain-controlled exoskeleton system based on brain-computer interface (BCI) technology to enhance rehabilitation in post-stroke patients. This study designed a brain-controlled exoskeleton system consisting of open-loop control and closed-loop feedback. In the open-loop control stage, patients control the exoskeleton's standing, walking, and sitting commands through electroencephalogram (EEG) signals; in the closed-loop feedback stage, the rehabilitation effect is evaluated through brainwave analysis and clinical evaluation. Experimental results demonstrate that the system can effectively assist patients in regaining motor control during training and elicit significant neurophysiological responses in the preparation and execution stages of movement. Additionally, clinical evaluation results showed that patients made notable progress in muscle strength and functional recovery. Although the study sample size was small (n=3) and the treatment period was short, the study highlights the potential application of brain-controlled exoskeleton systems in post-stroke rehabilitation. Future studies should expand the sample size and include long-term follow-up to further assess its clinical feasibility and long-term effects.
Shi-Yong Luo, Po-Hsun Cheng, Chia-Hsin Chen, Zhi-Ting Chen, Yu-Zhen Liu, Li-Wei Ko
CIBCB7
2025 Gait-Triggered Functional Electrical Stimulation: An EMG-IMU-FES coordinated closed-loop stimulation system for gait rehabilitation of stroke survivors
abstract
The application of functional electrical stimulation (FES) for ambulatory rehabilitation training of lower limbs has been reported to improve the symptoms associated with muscle spasticity. However, detailed investigation of the neurophysiological changes after actively-triggered FES training of the stroke patients may be required. In this study, a gait-triggered FES (GT-FES) system for post-stroke rehabilitation has been proposed whereby an FES system was incorporated with inertia measurement units (IMUs) and electromyogram (EMG) recording, and the FES will be triggered when dorsiflexion and EMG amplitude of the tibialis anterior muscle were detected. GT-FES was also paired along with the collection and analysis algorithms of multimodal neurophysiological data, including electroencephalogram (EEG), EMG, and kinematic gait data to assess changes in gait performance, and activity in the sensorimotor cortex. Nine healthy subjects and eleven post-stroke patients were recruited in this study. Gait results indicated that the ankle dorsiflexion of Brunnstrom stage IV stroke patients (BR-IV) had an improvement of 1.828° (p=0.0023) during and 3.092° (p=2.4×10−4) after GT-FES training, and the gait cadence had a significant improvement after GT-FES training (9.063 to 9.539 steps; p=0.0469). Neurologically, EEG desynchronization in the alpha frequency range (10 Hz) tended to strengthen in BR-IV. Such an evaluation of the functional and neurophysiological activities immediately after GT-FES training shows the beneficial impacts of GTFES therapies in different stages of stroke rehabilitation, allowing for the development of more targeted therapies and serving as a component for understanding the neural changes which occur with GT-FES, towards the overall goal of improving long-term stroke rehabilitation.
Siddharth Shaw, Kuen-Han Yu, Chun-Ren Phang, Li-Wei Ko
SMC4
2024 Forecasting Slow-Wave Sleep Deficiency Through Stress-Related Markers in Forehead EEG
abstract
Sleep quality is critical for human well-being. Lack of sleep and poor sleep quality impair daily cognitive functions and health. While stress has been recognized as a detrimental factor on sleep quality, the relationship between pre-sleep stress level, resting EEG and subsequent sleep structure remains to be explored. This study presents a novel approach that evaluates pre-sleep stress levels using a 2-channel EEG to predict slow-wave sleep (SWS) deficiency. We recorded forehead EEG immediately before sleep onset, then utilized power spectra and entropy analysis to extract stress-related neurological features, including beta/delta correlation, alpha asymmetry, fuzzy entropy (FuzzEn), and spectral entropy (SpEn). We found that individuals with SWS deficiency exhibited signs of stress, such as a robust beta/delta correlation, higher alpha asymmetry, and increased FuzzEn. Conversely, individuals with ample SWS displayed weak beta/delta correlation and reduced FuzzEn in EEG recordings. Finally, we tested the robustness of the selected neuro markers with two supervised learning models and found that the selected markers predict SWS deficiency with an accuracy above 70%. Our study demonstrated that stress-related neurological markers derived from pre-sleep EEG can effectively predict SWS deficiency. The proposed method can be integrated with a portable EEG device and sleep-improving interventions to develop a personalized sleep-improvement solution.
Cheng-Hua Su, Li-Wei Ko, Tzyy-Ping Jung, Julie Onton, Shey-Cherng Tzou, Jia-chi Juang, Chung-Yao Hsu
SMC2
2024 Development of an Adaptive Artifact Subspace Reconstruction Based on Hebbian/Anti-Hebbian Learning Networks for Enhancing BCI Performance
abstract
Brain-computer interface (BCI) actively translates the brain signals into executable actions by establishing direct communication between the human brain and external devices. Recording brain activity through electroencephalography (EEG) is generally contaminated with both physiological and nonphysiological artifacts, which significantly hinders the BCI performance. Artifact subspace reconstruction (ASR) is a well-known statistical technique that automatically removes artifact components by determining the rejection threshold based on the initial reference EEG segment in multichannel EEG recordings. In real-world applications, the fixed threshold may limit the efficacy of the artifact correction, especially when the quality of the reference data is poor. This study proposes an adaptive online ASR technique by integrating the Hebbian/anti-Hebbian neural networks into the ASR algorithm, namely, principle subspace projection ASR (PSP-ASR) and principal subspace whitening ASR (PSW-ASR) that segmentwise self-organize the artifact subspace by updating the synaptic weights according to the Hebbian and anti-Hebbian learning rules. The effectiveness of the proposed algorithm is compared to the conventional ASR approaches on benchmark EEG dataset and three BCI frameworks, including steady-state visual evoked potential (SSVEP), rapid serial visual presentation (RSVP), and motor imagery (MI) by evaluating the root-mean-square error (RMSE), the signal-to-noise ratio (SNR), the Pearson correlation, and classification accuracy. The results demonstrated that the PSW-ASR algorithm effectively removed the EEG artifacts and retained the activity-specific brain signals compared to the PSP-ASR, standard ASR (Init-ASR), and moving-window ASR (MW-ASR) methods, thereby enhancing the SSVEP, RSVP, and MI BCI performances. Finally, our empirical results from the PSW-ASR algorithm suggested the choice of an aggressive cutoff range of c = 1-10 for activity-specific BCI applications and a moderate range of for the benchmark dataset and general BCI applications.
Bo-Yu Tsai, Sandeep Vara Sankar Diddi, Li-Wei Ko, Shuu-Jiun Wang, Chi-Yuan Chang, Tzyy-Ping Jung
IEEE Trans. Neural Networks Learn. Syst.3
2023 Diversity and Suitability of the State-of-the-Art Wearable and Wireless EEG Systems Review
abstract
Wireless electroencephalography (EEG) systems have been attracting increasing attention in recent times. Both the number of articles discussing wireless EEG and their proportion relative to general EEG publications have increased over years. These trends indicate that wireless EEG systems could be more accessible to researchers and the research community has recognized the potential of wireless EEG systems. To explore the development and diverse applications of wireless EEG systems, this review highlights the trends in wearable and wireless EEG systems over the past decade and compares the specifications and research applications of the major wireless systems marketed by 16 companies. For each product, five parameters (number of channels, sampling rate, cost, battery life, and resolution) were assessed for comparison. Currently, these wearable and portable wireless EEG systems have three main application areas: consumer, clinical, and research. To address this multitude of options, the article also discussed the thought process to find a suitable device that meets personalization and use cases specificities. These investigations suggest that low-price and convenience are key factors for consumer applications, wireless EEG systems with FDA or CE-certification may be more suitable for clinical settings, and devices that provide raw EEG data with high-density channels are important for laboratory research. This article presents an overview of the current state of the wireless EEG systems specifications and possible applications and serves as a guide point as it is expected that more influential and novel research will cyclically promote the development of such EEG systems.
Congying He, Yu-Yi Chen, Chun-Ren Phang, Cory Stevenson, I-Ping Chen, Tzyy-Ping Jung, Li-Wei Ko
IEEE J. Biomed. Health Informatics7
2020 Extraction of SSVEPs-Based Inherent Fuzzy Entropy Using a Wearable Headband EEG in Migraine Patients
abstract
Inherent fuzzy entropy is an objective measurement of electroencephalography (EEG) complexity reflecting the robustness of brain systems. In this study, we present a novel application of multiscale relative inherent fuzzy entropy using repetitive steady-state visual evoked potentials (SSVEPs) to investigate EEG complexity change between two migraine phases, i.e., interictal (baseline) and preictal (before migraine attacks) phases. We used a wearable headband EEG device with O1, Oz, O2, and Fpz electrodes to collect EEG signals from 80 participants [40 migraine patients and 40 healthy controls (HCs)] under the following two conditions: During resting state and SSVEPs with five 15-Hz photic stimuli. We found a significant enhancement in occipital EEG entropy with increasing stimulus times in both HCs and patients in the interictal phase, but a reverse trend in patients in the preictal phase. In the 1st SSVEP, occipital EEG entropy of the HCs was significantly lower than that of patents in the preictal phase (FDRadjustedp <; 0.05). Regarding the transitional variance of EEG entropy between the 1st and 5th SSVEPs, patients in the preictal phase exhibited significantly lower values than patients in the interictal phase (FDR-adjustedp <; 0.05). Furthermore, in the classification model, the AdaBoost ensemble learning showed an accuracy of 81 ± 6% and area under the curve of 0.87 for classifying interictal and preictal phases. In contrast, there were no differences in EEG entropy among groups or sessions by using other competing entropy models, including approximate entropy, sample entropy, and fuzzy entropy on the same dataset. In conclusion, inherent fuzzy entropy offers novel applications in visual stimulus environments and may have the potential to provide a preictal alert to migraine patients.
Zehong Cao, Chin-Teng Lin, Kuan-Lin Lai, Li-Wei Ko, Jung-Tai King, Kwong-Kum Liao, Jong-Ling Fuh, Shuu-Jiun Wang
IEEE Trans. Fuzzy Syst.4
2019 Target Classification in a Novel SSVEP-RSVP Based BCI Gaming System
abstract
Recently game-based brain-computer interface (BCI) systems using electroencephalography (EEG) has been gaining popularity, providing a sophisticated experience to its users. Here we present such a novel hybrid system based on rapid serial visual presentation (RSVP) in conjunction with steady-state visual evoked potentials (SSVEP). Based on a matching computer game Jewel Quest a game is designed wherein a sequence of jewel images containing rare targets (<; 3%) in an RSVP paradigm is presented on a display at four distinct locations each flickering at different rates (4, 5, 6 and 7 Hz). A score is awarded upon successful detection of target image from neural signals. During real-time implementation to achieve higher classification speeds, EEG signals were epoched at the onset of each image, creating a high degree of class overlap and imbalance. Given these challenges in our EEG datasets, we present classifiers that can classify single-trial EEG epochs at the onset of target image presentation accurately. Initial results from 14 subjects indicate Hidden Markov Model (HMM) with Dirichlet emission probabilities provide ~1% higher, on average, the area under the precision-recall curve (AUC-PR) compared to the ensemble technique Bagging, commonly used to handle class imbalance.
Tapsya Nayak, Li-Wei Ko, Tzyy-Ping Jung, Yufei Huang 0001
SMC2
2017 Develop a personalized intelligent music selection system based on heart rate variability and machine learning
Ming-Chuan Chiu, Li-Wei Ko
Multim. Tools Appl.2
2016 Neural Oscillations in Temporoparietal Lobes under Inhibitory Control in a Naturalistic Situation
abstract
The stop-signal paradigm has been commonly applied as a measure of inhibitory control due to its exclusive ability to capture theoretically important parameters related to the response inhibition. To observe the inhibitory function in realistic environmental settings, we designed a battlefield scenario (BFS), which is inspired by real condition like open fire between soldier and terrorist for saving civilian because terrorism is serious problem worldwide. The stop-signal task has been widely adopted as a way to parametrically quantify the response inhibition process. This study compared the response inhibition in two different scenarios: One used traditional simple visual symbols as go and stop signals i.e. symbol scenario (SBS), and the other translated the typical design into a battlefield scenario. The outcomes confirmed that both scenarios induced increased activity in the right inferior frontal gyrus (IFG) and pre supplementary motor area (preSMA), which have been associated to response inhibition. Particularly, in right temporoparietal junction (rTPJ) we found both higher BOLD activation and EEG power modulation in the battlefield scenario than in the traditional scenario after the stop stimulus onset.
Li-Wei Ko, Rupesh Kumar Chikara, Yi-Cheng Shih, Erik C. Chang
BIBE1
2015 Classification of migraine stages based on resting-state EEG power
abstract
Migraine is a chronic neurological disease characterized by recurrent moderate to severe headaches during a period like one month often in association with symptoms in human brain and autonomic nervous system. Normally, migraine symptoms can be categorized into four different stages: inter-ictal, pre-ictal, ictal, and post-ictal stages. Since migraine patients are difficulty knowing when they will suffer migraine attacks, therefore, early detection becomes an important issue, especially for low-frequency migraine patients who have less than 5 times attacks per month. The main goal of this study is to develop a migraine-stage classification system based on migraineurs' resting-state EEG power. We collect migraineurs' O1 and O2 EEG activities during closing eyes from occipital lobe to identify pre-ictal and non-pre-ictal stages. Self-Constructing Neural Fuzzy Inference Network (SONFIN) is adopted as the classifier in the migraine stages classification which can reach the better classification accuracy (66%) in comparison with other classifiers. The proposed system is helpful for migraineurs to obtain better treatment at the right time.σ
Zehong Cao, Li-Wei Ko, Kuan-Lin Lai, Song-Bo Huang, Shuu-Jiun Wang, Chin-Teng Lin
IJCNN2
2015 Single channel wireless EEG device for real-time fatigue level detection
abstract
Driver fatigue problem is one of the important factors of traffic accidents. Recent years, many research had investigated that using EEG signals can effectively detect driver's drowsiness level. However, real-time monitoring system is required to apply these fatigue level detection techniques in the practical application, especially in the real-road driving. Therefore, it required less channels, portable and wireless, real-time monitoring and processing techniques for developing the real-time monitoring system. In this study, we develop a single channel wireless EEG device which can real-time detect driver's fatigue level on the mobile device such as smart phone or tablet. The developed device is investigated to obtain a better and precise understanding of brain activities of mental fatigue under driving, which is of great benefit for devolvement of detection of driving fatigue system. This system consists of a Bluetooth-enabled one channel EEG, a regression model, and smartphone, which was a platform recording and transforming the raw EEG data to useful driving status. In the experiment, this was a sustained-attention driving task to implement in a virtual-reality (VR) driving simulator. To training model and develop the system, we were performed for 15 subjects to study Electroencephalography (EEG) brain dynamics by using a mobile and wireless EEG device. Based on the outstanding training results, the leave-one-subject-out cross validation test obtained 90% fatigue detection accuracy. These results indicate that the combination of a smartphone and wireless EEG device constitutes an effective and easy wearable solution for detecting and preventing driver fatigue in real driving environments.
Li-Wei Ko, Wei-Kai Lai, Wei-Gang Liang, Chun-Hsiang Chuang, Shao-Wei Lu, Yi-Chen Lu, Tien-Yang Hsiung, Hsu-Hsuan Wu, Chin-Teng Lin
IJCNN1
2015 An EEG-based perceptual function integration network for application to drowsy driving
Chun-Hsiang Chuang, Chih-Sheng Huang, Li-Wei Ko, Chin-Teng Lin
Knowl. Based Syst.3
2014 An EEG-based approach for evaluating audio notifications under ambient sounds
abstract
Audio notifications are an important means of prompting users of electronic products. Although useful in most environments, audio notifications are ineffective in certain situations, especially against particular auditory backgrounds or when the user is distracted. Several studies have used behavioral performance to evaluate audio notifications, but these studies failed to achieve consistent results due to factors including user subjectivity and environmental differences; thus, a new method and more objective indicators are necessary. In this study, we propose an approach based on electroencephalography (EEG) to evaluate audio notifications by measuring users' auditory perceptual responses (mismatch negativity) and attention shifting (P3a). We demonstrate our approach by applying it to the usability testing of audio notifications in realistic scenarios, such as users performing a major task amid ambient noises. Our results open a new perspective for evaluating the design of the audio notifications.
Yi-Chieh Lee, Wen-Chieh Lin, Jung-Tai King, Li-Wei Ko, Fu-Yin Cherng
CHI4
2014 Developing a few-channel hybrid BCI system by using motor imagery with SSVEP assist
abstract
Generally, Steady-State Visually Evoked Potentials (SSVEP) has widely recognized advantages, like being easy to use, requiring little user training [1], while Motor Imagery (MI) is not easy to introduce for some subjects. This work introduces a hybrid brain-computer interface (BCI) combines MI and SSVEP strategies - such an approach allows us to improve performance and universality of the system, and also the number of EEG electrodes from 32 to 3 in central area can increase the efficiency of EEG preprocessing to design an effective and easy way to use hybrid BCI system. In this study the Common Spatial Pattern (CSP) algorithm was introduced as a feature extraction method, which provides a high accuracy in event-related synchronization/desynchronization (ERS/ERD)-based BCL The four most common classifiers (KNNC, PARZENDC, LDC, SVC) were used for accuracy estimation. Results show that support vector classifier (SVC) and K-nearest-neighbor (KNN) classifier provide better performance than others, and it is possible to reach the same good accuracy using 3-channel (C3, Cz, C4) hybrid BCI system, as with usual 32-channel system.
Li-Wei Ko, Shih-Chuan Lin, Meng-Shue Song, Oleksii Komarov
IJCNN1
2014 Gaming controlling via brain-computer interface using multiple physiological signals
abstract
Using physiological signals to control brain-computer interface (BCI) becomes more popular. Among many kinds of physiological signals, Electrooculography (EOG) signal is more stable which can be used to control BCI systems based on eye movement detection and signal processing methods. Also, the use of electroencephalographic (EEG) signals has become the most common approach for a BCI because of their usability and strong reliability. In this paper, we described a signal processing method, which uses a wireless EEG-based BCI system designed to be worn near forehead that can detect both EEG and EOG signals, for detecting eye movements to have 9 direction controls (via EOG) and one action of execution (via EEG). This system included a wireless EEG signal acquisition device, a mechanism that can be worn stably, and an application program (APP) with signal processing algorithms. This algorithm and its classification procedure provided an effective method for identifying eye movements and attention. Finally, we designed a baseball game to test the BCI system. The results demonstrated that player can control the game well with high accuracy.
Shi-An Chen, Chih-Hao Chen, Jheng-Wei Lin, Li-Wei Ko, Chin-Teng Lin
SMC4
2013 Applying the fuzzy c-means based dimension reduction to improve the sleep classification system
abstract
Having a well sleep quality is important factor in our daily life. The evaluation of sleep stages has become an important issue due to the distribution of sleep stages across a whole night relates to sleep quality. This study aims to propose a sleep classification system, consists of a preliminary wake detection rule, sleep feature extraction, fuzzy c-means based dimension reduction, support vector machine with radial basis function kernel, and adaptive adjustment scheme, with only FP1 and FP2 electroencephalography. Compared with the results from the sleep technologist, the average accuracy and Kappa coefficient of the proposed sleep classification system is 70.92% and 0.6130, respectively, for individual 10 normal subjects. Thus, the proposed sleep classification system could provide a preliminary report of sleep stages to assistant doctors to make decision if a patient needs to have a detailed testing in a sleep laboratory.
Chih-Sheng Huang, Chun-Ling Lin, Wen-Yu Yang, Li-Wei Ko, Sheng-Yi Liu, Chin-Teng Lin
FUZZ-IEEE4
2013 System modeling and synchronization of nonlinear chaotic systems with uncertainty and disturbance by innovative fuzzy modeling strategy
abstract
In this paper, an application of the innovative fuzzy model [1] is applied to simulate and synchronize two classical Sprott chaotic systems with unknown noise and disturbance. In traditional Takagi-Sugeno fuzzy (T-S fuzzy) model, there will be 2Nlinear subsystems (according to 2Nfuzzy rules) and m × 2Nequations in the T-S fuzzy system, where N is the number of minimum nonlinear terms and m is the order of the system. Through the new fuzzy model, a complicated nonlinear system is linearized to a simple form - linear coupling of only two linear subsystems and the numbers of fuzzy rules can be reduced from 2Nto 2 × N. The fuzzy equations become much simpler. There are two Sprott systems in numerical simulations to show the effectiveness and feasibility of new model.
Shih-Yu Li, Li-Wei Ko, Chin-Teng Lin, Lap-Mou Tam, Hsien-Keng Chen, Seng-Kin Lao
FUZZ-IEEE2
2013 Real-time assessment of vigilance level using an innovative Mindo4 wireless EEG system
abstract
Monitoring the neurophysiological activities of driver in an operational environment poses a severe measurement challenge using a current laboratory-oriented biosensor technology. The aims of this research are to 1) introduce a dry and wireless EEG system used for conveniently recording EEG signals from forehead regions, 2) propose an effective system for processing EEG recordings and translating them into the vigilance level, and 3) implement the proposed system with a JAVA-based graphical user interface (GUI) for online analysis. To validate the performance of the proposed system, this study recruited eight voluntary subjects to participate a 90-min sustained-attention driving task in a virtual-realistic driving environment. Physiological evidence obtained from the power spectral analysis showed that the dry EEG system could distinguish an alert EEG from a drowsy EEG by evaluating the spectral dynamics of delta and alpha activities. Furthermore, the experimental result of the comparison of the prediction performance using four forehead electrode sites (AF8, FP2, FP1, and AF7) implied that a single-electrode EEG signal used in the mobile and wireless EEG system is able to obtain a high prediction accuracy (~93%). Taken together, the proposed system applied a dry-EEG device combined with an effective algorithm can be a promising technology for real driving applications.
Chin-Teng Lin, Chun-Hsiang Chuang, Chih-Sheng Huang, Yen-Hsuan Chen, Li-Wei Ko
ISCAS5
2013 HCS-Neurons: identifying phenotypic changes in multi-neuron images upon drug treatments of high-content screening
abstract
BACKGROUND: High-content screening (HCS) has become a powerful tool for drug discovery. However, the discovery of drugs targeting neurons is still hampered by the inability to accurately identify and quantify the phenotypic changes of multiple neurons in a single image (named multi-neuron image) of a high-content screen. Therefore, it is desirable to develop an automated image analysis method for analyzing multi-neuron images. RESULTS: We propose an automated analysis method with novel descriptors of neuromorphology features for analyzing HCS-based multi-neuron images, called HCS-neurons. To observe multiple phenotypic changes of neurons, we propose two kinds of descriptors which are neuron feature descriptor (NFD) of 13 neuromorphology features, e.g., neurite length, and generic feature descriptors (GFDs), e.g., Haralick texture. HCS-neurons can 1) automatically extract all quantitative phenotype features in both NFD and GFDs, 2) identify statistically significant phenotypic changes upon drug treatments using ANOVA and regression analysis, and 3) generate an accurate classifier to group neurons treated by different drug concentrations using support vector machine and an intelligent feature selection method. To evaluate HCS-neurons, we treated P19 neurons with nocodazole (a microtubule depolymerizing drug which has been shown to impair neurite development) at six concentrations ranging from 0 to 1000 ng/mL. The experimental results show that all the 13 features of NFD have statistically significant difference with respect to changes in various levels of nocodazole drug concentrations (NDC) and the phenotypic changes of neurites were consistent to the known effect of nocodazole in promoting neurite retraction. Three identified features, total neurite length, average neurite length, and average neurite area were able to achieve an independent test accuracy of 90.28% for the six-dosage classification problem. This NFD module and neuron image datasets are provided as a freely downloadable MatLab project at http://iclab.life.nctu.edu.tw/HCS-Neurons. CONCLUSIONS: Few automatic methods focus on analyzing multi-neuron images collected from HCS used in drug discovery. We provided an automatic HCS-based method for generating accurate classifiers to classify neurons based on their phenotypic changes upon drug treatments. The proposed HCS-neurons method is helpful in identifying and classifying chemical or biological molecules that alter the morphology of a group of neurons in HCS.
Phasit Charoenkwan, Eric Hwang, Robert W. Cutler, Hua-Chin Lee, Li-Wei Ko, Hui-Ling Huang, Shinn-Ying Ho
BMC Bioinform.5
2013 Fuzzy adaptive synchronization of time-reversed chaotic systems via a new adaptive control strategy
Shih-Yu Li, Cheng-Hsiung Yang, Shi-An Chen, Li-Wei Ko, Chin-Teng Lin
Inf. Sci.4
2013 EEG-Based Learning System for Online Motion Sickness Level Estimation in a Dynamic Vehicle Environment
abstract
Motion sickness is a common experience for many people. Several previous researches indicated that motion sickness has a negative effect on driving performance and sometimes leads to serious traffic accidents because of a decline in a person's ability to maintain self-control. This safety issue has motivated us to find a way to prevent vehicle accidents. Our target was to determine a set of valid motion sickness indicators that would predict the occurrence of a person's motion sickness as soon as possible. A successful method for the early detection of motion sickness will help us to construct a cognitive monitoring system. Such a monitoring system can alert people before they become sick and prevent them from being distracted by various motion sickness symptoms while driving or riding in a car. In our past researches, we investigated the physiological changes that occur during the transition of a passenger's cognitive state using electroencephalography (EEG) power spectrum analysis, and we found that the EEG power responses in the left and right motors, parietal, lateral occipital, and occipital midline brain areas were more highly correlated to subjective sickness levels than other brain areas. In this paper, we propose the use of a self-organizing neural fuzzy inference network (SONFIN) to estimate a driver's/passenger's sickness level based on EEG features that have been extracted online from five motion sickness-related brain areas, while either in real or virtual vehicle environments. The results show that our proposed learning system is capable of extracting a set of valid motion sickness indicators that originated from EEG dynamics, and through SONFIN, a neuro-fuzzy prediction model, we successfully translated the set of motion sickness indicators into motion sickness levels. The overall performance of this proposed EEG-based learning system can achieve an average prediction accuracy of ~82%.
Chin-Teng Lin, Shu-Fang Tsai, Li-Wei Ko
IEEE Trans. Neural Networks Learn. Syst.3
2012 Motion sickness estimation system
abstract
Motion sickness occurs when the brain receives conflicting sensory information from body, inner ear and eyes [1]. In some cases, a decreased ability to actively control the body's postural motion also causes motion sickness [2][3]. Many previous studies have indicated that motion sickness had negative effect on driving performance, and sometimes lead to serious traffic accidents due to self-control ability decline. Therefore motion sickness becomes a very important issue in our daily life especially considering driving safety. There are many attempts made by researchers to realize motion sickness, and detect motion sickness in the early stage. Although many motion-sickness-related biomarkers have been identified, estimating human motion sickness level (MSL) remains a challenge in operational environment. In our past studies, we found that features in the occipital area were highly correlated with the driver's driving performance. In this study, we designed a virtual-reality (VR) based driving environment with instinct-MSL-reporting mechanism. When a subject performed a driving task, his/her brain EEG was recorded simultaneously. From those EEG data, features associated with left motor brain area, parietal brain area and occipital midline brain area which predicted MSL were extracted by an optimal classifier implemented by an inheritable bi-objective combinatorial genetic algorithm (IBCGA) with support vector machine. Unlike traditional correlation-based method, IBCGA aims to select a small set of EEG features and maximize the prediction accuracy simultaneously in BCI applications. Once the optimal feature set predicting MSL is successfully found, a driver's cognitive state can be monitored.
Chin-Teng Lin, Shu-Fang Tsai, Hua-Chin Lee, Hui-Ling Huang, Shinn-Ying Ho, Li-Wei Ko
IJCNN6
2012 Development of adaptive QRS detection rules based on center differentiation method for clinical application
abstract
Interpretation of cardiac rhythms is highly dependent on accurate detection of atrial activity. The robustness is an important requirement for clinical usage. This study presents an adaptive QRS detection method for real-time clinical ECG signals. In this method, center differentiation is applied as a whitening filer, and a composite function enhances the high frequency QRS energy. To robustly detect clinical data, a novel threshold selection method based on statistics is proposed. Moreover, this study provides a benchmarking clinical dataset acquired from cardiac patients. Our extensive experimental results using the MIT-BIH arrhythmia database show that our technique can detect beats with 99.67% accuracy, and the sensitivity is 99.83%. With the exceptional QRS detection result, further testing of the proposed method with clinical data shows the accuracy for atrial and ventricular arrhythmias is 82.9% and 90.2%, respectively.
Shiau-Ru Yang, Sheng-Chih Hsu, Shao-Wei Lu, Li-Wei Ko, Chin-Teng Lin
ISCAS4
2012 Biosensor Technologies for Augmented Brain-Computer Interfaces in the Next Decades
abstract
The study of brain-computer interfaces (BCIs) has undergone 30 years of intense development and has grown into a rich and diverse field. BCIs are technologies that enable direct communication between the human brain and external devices. Conventionally, wet electrodes have been employed to obtain unprecedented sensitivity to high-temporal-resolution brain activity; recently, the growing availability of various sensors that can be used to detect high-quality brain signals in a wide range of clinical and everyday environments is being exploited. This development of biosensing neurotechnologies and the desire to implement them in real-world applications have led to the opportunity to develop augmented BCIs (ABCIs) in the upcoming decades. An ABCI is similar to a BCI in that it relies on biosensors that record signals from the brain in everyday environments; the signals are then processed in real time to monitor the behavior of the human. To use an ABCI as a mobile brain imaging technique for everyday, real-life applications, the sensors and the corresponding device must be lightweight and the equipment response time must be short. This study presents an overview of the wide range of biosensor approaches currently being applied to ABCIs, from their use in the laboratory to their application in clinical and everyday use. The basic principles of each technique are described along with examples of current applications of cutting-edge neuroscience research. In summary, we show that ABCI techniques continue to grow and evolve, incorporating new technologies and advances to address ever more complex and important neuroscience issues, with advancements that are envisioned to lead to a wide range of real-life applications.
Lun-De Liao, Chin-Teng Lin, Kaleb McDowell, Alma E. Wickenden, Klaus Gramann, Tzyy-Ping Jung, Li-Wei Ko, Jyh-Yeong Chang
Proc. IEEE7
2011 EEG-Based Motion Sickness Estimation Using Principal Component Regression
Li-Wei Ko, Chun-Shu Wei, Shi-An Chen, Chin-Teng Lin
ICONIP (1)1
2011 EEG-based brain dynamics of driving distraction
abstract
Distraction during driving has been recognized as a significant cause of traffic accidents. The aim of this study is to investigate Electroencephalography (EEG) -based brain dynamics in response to driving distraction. To study human cognition under specific driving tasks in a simulated driving experiment, this study utilized two simulated events including unexpected car deviations and mathematics questions. The raw data were first separated into independent brain sources by Independent Component Analysis. Then, the EEG power spectra were used to evaluate the time-frequency brain dynamics. Results showed that increases of theta band and beta band power were observed in the frontal cortex. Further analysis demonstrated that reaction time and multiple cortical EEG power had high correlation. Thus, this study suggested that the features extracted by EEG signal processing, which were the theta power increases in frontal area, could be used as the distracted indexes for early detection of driver inattention in real driving.
Chin-Teng Lin, Shi-An Chen, Li-Wei Ko, Yu-Kai Wang
IJCNN3
2011 Genetic feature selection in EEG-based motion sickness estimation
abstract
Motion sickness is a common symptom that occurs when the brain receives conflicting information about the sensation of movement. Many motion sickness biomarkers have been identified, and electroencephalogram (EEG)-based motion sickness level estimation was found feasible in our previous study. This study employs genetic feature selection to find a subset of EEG features that can further improve estimation performance over the correlation-based method reported in the previous studies. The features selected by genetic feature selection were very different from those obtained by correlation analysis. Results of this study demonstrate that genetic feature selection is a very effective method to optimize the estimation of motion-sickness level. This demonstration could lead to a practical system for noninvasive monitoring of the motion sickness of individuals in real-world environments.
Chun-Shu Wei, Li-Wei Ko, Shang-Wen Chuang, Tzyy-Ping Jung, Chin-Teng Lin
IJCNN2
2011 Implementation of a motion sickness evaluation system based on EEG spectrum analysis
abstract
Motion sickness is a normal response to real, perceived, or even anticipated movement. People tend to get motion sickness on a moving boat, train, airplane, car, or amusement park rides. Motion sickness occurs when the body, the inner ear, and the eyes send conflicting signals to the brain. Sensory conflict theory that came about in the 1970's has become the most widely accepted theorem of motion-sickness among scientists [1]. The theory proposed that the conflict between the incoming sensory inputs could induce motion- sickness. However, some new research studies have appeared to tackle the issue of the vestibular function in central nervous system (CNS). In the previous human subject studies, researchers attempt to confirm the brain areas involved in the conflict in multi-modal sensory systems by means of clinical or anatomical methods. Our past studies had investigated the EEG activities correlated with motion sickness in a virtual-reality based driving simulator. We found that the parietal, motor, occipital brain regions exhibited significant EEG power changes in response to vestibular and visual stimuli. Based on these experimental results, we attempt to implement an EEG-based evaluation system to estimate subject's motion sickness level upon the major EEG power spectra from these motion sickness related brain area in this study. The evaluation system can be applied to early detect the subject's motion sickness level and prevent the uncomfortable syndromes occurred in advance in our daily life.
Chun-Shu Wei, Shang-Wen Chuang, Li-Wei Ko, Tzyy-Ping Jung, Chin-Teng Lin
ISCAS4
2010 Driver's cognitive state classification toward brain computer interface via using a generalized and supervised technology
abstract
Growing numbers of traffic accidents had become a serious social safety problem in recent years. The main factor of the high fatalities was the obvious decline of the driver's cognitive state in their perception, recognition and vehicle control abilities while being sleepy. The key to avoid the terrible consequents is to build a detecting system for ongoing assessment of driver's cognitive state. A quickly growing research, brain-computer interface (BCI), offers a solution offering great assistance to those who require alternative communicatory and control mechanisms. In this study, we propose an alertness/drowsiness classification system based on investigating electroencephalographic (EEG) brain dynamics in lane-keeping driving experiments in a virtual reality (VR) driving environment with a motion platform. The core of the classification system is composed of dimension reduction technique and classifier learning algorithm. In order to find the suitable method for better describing the data structure, we explore the performances using different feature extraction and feature selection methods with different classifiers. Experiment results show that the accuracy is over 80% in most combinations and even near 90% under Principal Component Analysis (PCA) and Nonparametric Weighted Feature Extraction (NWFE) going with Gaussian Maximum Likelihood classifier (ML) and k-Nearest-Neighbor classifier (kNN), respectively. In addition, this developed classification system can also solve the individual brain dynamic differences caused from different subjects and overcome the subject dependent limitation. The optimized solution with better accuracy performance out of all combinations can be considered to implement in the kernel brain-computer interface.
Chun-Hsiang Chuang, Pei-Chen Lai, Li-Wei Ko, Bor-Chen Kuo, Chin-Teng Lin
IJCNN3
2010 An EEG-based classification system of Passenger's motion sickness level by using feature extraction/selection technologies
abstract
Past studies reported that the main electrogastrography (EEG) dynamic changes related to motion sickness (MS) were occurred in occipital, parietal, and somatosensory brain area, especially in the power increasing of the alpha band (8-13 Hz) and theta band (4-7 Hz) which had positive correlation with the subjective MS level. Depend on these main findings correlated with MS, we attempt to develop an EEG based classification system to automatically classify subject's MS level and find the suitable EEG features via common feature extraction, selection and classifiers technologies in this study. If we can find the regulations and then develop an algorithm to predict MS occurring, it would be a great benefit to construct a safe and comfortable environment for all drivers and passengers when they are cruising in the car, bus, ship or airplane. EEG is one of the best methods for monitoring the brain dynamics induced by motion-sickness because of its high temporal resolution and portability. After collecting the EEG signals and subjective MS level in a realistic driving environment, we first do the data pre-processing part including ICA, component clustering analysis and time-frequency analysis. Then we adopt three common feature extractions and two feature selections (FE/FS) technologies to extract or select the correlated features such as principal component analysis (PCA), linear discriminate analysis (LDA), nonparametric weighted feature extraction (NWFE), forward feature selections (FFS) and backward feature selections (BFS) and feed the feature maps into three classifiers (Gaussian Maximum Likelihood Classifier (ML), k-Nearest-Neighbor Classifier (kNN) and Support Vector Machine (SVM)). Experimental results show that classification performance of all our proposed technologies can be reached almost over 95%. It means it is possible to apply the effective technology combination to predict the subject's MS level in the real life applications. The better combination in this study is using LDA and Gaussian based ML classifier. This advantage can be widely used in machine learning area for developing the prediction algorithms in the future.
Yi-Hsin Yu, Pei-Chen Lai, Li-Wei Ko, Chun-Hsiang Chuang, Bor-Chen Kuo, Chin-Teng Lin
IJCNN3
2010 EEG-based cognitive state monitoring and predition by using the self-constructing neural fuzzy system
abstract
Driver's cognitive state monitoring has been implicated as a causal factor for the safety driving issue, especially when the driver fell asleep or distracted in driving. In our past studies, we found that the EEG power spectrum changes were highly correlated with the driver's driving behavior performance. In this study, we attempt to construct an EEG-based self-constructing neural fuzzy system to monitor and predict the driver's cognitive state. The difficulties in developing such a system are lack of significant index for detecting drowsiness and the interference of the complicated noise in a realistic and dynamic driving environment. Our experimental results including correlation and prediction show that the performances of our proposed system are significantly higher than using the traditional neural networks. Besides, the proposed EEG-based self-constructing neural fuzzy system can be generalized and applied in the subjects' independent sessions. This unique advantage can be widely used in the real-life applications.
Fu-Chang Lin, Li-Wei Ko, Shi-An Chen, Ching-Fu Chen, Chin-Teng Lin
ISCAS2
2010 An intelligent telecardiology system using a wearable and wireless ECG to detect atrial fibrillation
abstract
This study presents a novel wireless, ambulatory, real-time, and autoalarm intelligent telecardiology system to improve healthcare for cardiovascular disease, which is one of the most prevalent and costly health problems in the world. This system consists of a lightweight and power-saving wireless ECG device equipped with a built-in automatic warning expert system. This device is connected to a mobile and ubiquitous real-time display platform. The acquired ECG signals are instantaneously transmitted to mobile devices, such as netbooks or mobile phones through Bluetooth, and then, processed by the expert system. An alert signal is sent to the remote database server, which can be accessed by an Internet browser, once an abnormal ECG is detected. The current version of the expert system can identify five types of abnormal cardiac rhythms in real-time, including sinus tachycardia, sinus bradycardia, wide QRS complex, atrial fibrillation (AF), and cardiac asystole, which is very important for both the subjects who are being monitored and the healthcare personnel tracking cardiac-rhythm disorders. The proposed system also activates an emergency medical alarm system when problems occur. Clinical testing reveals that the proposed system is approximately 94% accurate, with high sensitivity, specificity, and positive prediction rates for ten normal subjects and 20 AF patients. We believe that in the future a business-card-like ECG device, accompanied with a mobile phone, can make universal cardiac protection service possible.
Chin-Teng Lin, Kuan-Cheng Chang, Chun-Ling Lin, Chia-Cheng Chiang, Shao-Wei Lu, Shih-Sheng Chang, Bor-Shyh Lin, Hsin-Yueh Liang, Ray-Jade Chen, Yuan-Teh Lee, Li-Wei Ko
IEEE Trans. Inf. Technol. Biomed.11
2009 EEG-Based Spatial Navigation Estimation in a Virtual Reality Driving Environment
abstract
The aim of this study is to investigate the difference of EEG dynamics on navigation performance. A tunnel task was designed to classify subjects into allocentric or egocentric spatial representation users. Despite of the differences of mental spatial representation, behavioral performance in general were compatible between the two strategies subjects in the tunnel task. Task-related EEG dynamics in power changes were analyzed using independent component analysis (ICA), time-frequency and non-parametric statistic test. ERSP image results revealed navigation performance-predictive EEG activities which is is expressed in the parietal component by source reconstruction. For egocentric subjects, comparing to trails with well-estimation of homing angle, the power attenuation at the frequencies from 8 to 30 Hz (around alpha and beta band) was stronger when subjects overestimated homing directions, but the attenuated power was decreased when subjects were underestimated the homing angles. However, we did not found performance related brain activities for allocentric subjects, which may due to the functional dissociation between the use of allo- and egocentric reference frames.
Chin-Teng Lin, Fu-Shu Yang, Te-Chung Chiou, Li-Wei Ko, Jeng-Ren Duann, Klaus Gramann
BIBE4
2009 Automatic identification of useful independent components with a view to removing artifacts from eeg signal
abstract
Removal of artifacts is an important step in any research in /application of electroencephalogram (EEG). The artifacts may contain eye-blinking, muscle noise, heart signal, line noise, and environmental effect. Such noises often make the raw EEG signals not very useful for extraction/identification of physiological phenomena from EEG. The independent component analysis (ICA) is a popular technique for artifact removal in brain research and some reports demonstrate that ICA can remove the artifacts with lower (acceptable) loss of information. But, these reports select useful independent components manually, primarily by looking at the scalp-plots. This is of great inconvenience and is a barrier for BCI or real-time applications of EEG. In this paper, we demonstrate that machine learning methods could be quite effective to discriminate useful independent components from artifacts and our findings suggests the possibility of developing a ldquouniversalrdquo machine for artifact removal in EEG.
Hwa-Shan Huang, Nikhil R. Pal, Li-Wei Ko, Chin-Teng Lin
IJCNN3
2009 Assessment of musical training induced neuroplasticity by auditory event related potentials and neural networks
abstract
Music provides a tool to study numerous aspects of neuroscience from motion-skill to emotion since listening to and producing music involves many brain functions. The musician's brain is also regarded as an ideal model to investigate plasticity of the human brain. In this paper, an EEG-based neural network is proposed to assess neuroplasticity induced by musical training. A musical chord perception experiment is designed to acquire and compare the behavioral and neural responses of musicians and non-musicians. The ERPs elicited by the consonant and dissonant chords are combined together as the features of the model. The principle component analysis (PCA) is used to reduce feature dimensions and the dimension-reduced features are input to a feedforward neural network to recognize the brain potentials belong to a musician or a non-musician. The accuracy can reach 97% in average for leave-one-out cross validation of six subjects in this experiment. It demonstrates the feasibility of assessing effects of musical training by ERP signals elicited by musical chord perception.
Sheng-Fu Liang, Chi-Sheng Liu, Wan-Lin Chang, Yu-Hsiang Tsao, Li-Wei Ko, Chin-Teng Lin
IJCNN5
2008 Real-Time Embedded EEG-Based Brain-Computer Interface
Li-Wei Ko, I-Ling Tsai, Fu-Shu Yang, Jen-Feng Chung, Shao-Wei Lu, Tzyy-Ping Jung, Chin-Teng Lin
ICONIP (2)1
2008 An EEG-based subject- and session-independent drowsiness detection
abstract
Monitoring and predicting human cognitive state and performance using physiological signals such as Electroencephalogram (EEG) have recently gained increasing attention in the fields of brain-computer interface and cognitive neuroscience. Most previous psychophysiological studies of cognitive changes have attempted to use the same model for all subjects. However, the relatively large individual variability in EEG dynamics relating to loss of alertness suggests that for many operators, group statistics cannot be used to accurately predict changes in cognitive states. Attempts have also been made to build a subject-dependent model for each individual based on his/her pilot data to account for individual variability. However, such methods assume the cross-session variability in EEG dynamics to be negligible, which could be problematic due to electrode displacements, environmental noises, and skin-electrode impedance. Here first we show that the EEG power in the alpha and theta bands are strongly correlated with changes in the subject’s cognitive state reflected through his driving performance and hence his departure from alertness. Then under very mild and realistic assumptions we derive a model for the alert state of the person using EEG power in the alpha and theta bands. We demonstrate that deviations (computed by Mahalanobis distance) of the EEG power in the alpha and theta bands from the corresponding alert models are correlated to the changes in the driving performance. Finally, for detection of drowsiness we use a linear combination of deviations of the EEG power in the alpha band and theta band from the respective alert models that best correlates with subject’s changing level of alertness, indexed by subject’s behavioral response in the driving task. This approach could lead to a practical system for noninvasive monitoring of the cognitive state of human operators in attention-critical settings.
Chin-Teng Lin, Nikhil R. Pal, Chien-Yao Chuang, Tzyy-Ping Jung, Li-Wei Ko, Sheng-Fu Liang
IJCNN5
2008 Distraction-related EEG dynamics in virtual reality driving simulation
abstract
Driver distraction has been recognized as a significant cause of traffic incidents. Therefore, the aim of this study was to investigate electroencephalography (EEG) dynamics in response to distraction during driving. To study human cognition under specific driving task, we used virtual reality (VR) based driving simulation to simulate events including unexpected car deviations and mathematics questions (math) in real driving. For further assessing effects of the stimulus onset asynchrony (SOA) between the deviation onset and math presented on the EEG dynamics, we designed five cases with different SOA. The scalp-recorded EEG channel signals were first separated into independent brain sources by independent component analysis (ICA). Then, the event-related-spectral-perturbations (ERSP) measuring changes of EEG power spectra were used to evaluate the brain dynamics in time-frequency domains. Results showed that increases of theta band (5~7.8 Hz) and beta band (12.2~17 Hz) power were observed in the frontal cortex. Results demonstrated that reaction time and multiple cortical EEG sources responded to the driving deviations and math occurrences differentially in the stimulus onset asynchrony. Results also suggested that the theta band power increase in frontal area could be used as the distracted indexes for early detecting driver's inattention in the future.
Chin-Teng Lin, Hong-Zhang Lin, Tzai-Wen Chiu, Chih-Feng Chao, Yu-Chieh Chen, Sheng-Fu Liang, Li-Wei Ko
ISCAS7
2008 Noninvasive Neural Prostheses Using Mobile and Wireless EEG
abstract
Neural prosthetic technologies have helped many patients by restoring vision, hearing, or movement and relieving chronic pain or neurological disorders. While most neural prosthetic systems to date have used invasive or implantable devices for patients with inoperative or malfunctioning external body parts or internal organs, a much larger population of “healthy” people who suffer episodic or progressive cognitive impairments in daily life can benefit from noninvasive neural prostheses. For example, reduced alertness, lack of attention, or poor decision-making during monotonous, routine tasks can have catastrophic consequences. This study proposes a noninvasive mobile prosthetic platform for continuously monitoring high-temporal resolution brain dynamics without requiring application of conductive gels on the scalp. The proposed system features dry microelectromechanical system electroencephalography sensors, low-power signal acquisition, amplification and digitization, wireless telemetry, online artifact cancellation, and signal processing. Its implications for neural prostheses are examined in two sample studies: 1) cognitive-state monitoring of participants performing realistic driving tasks in the virtual-reality-based dynamic driving simulator and 2) the neural correlates of motion sickness in driving. The experimental results of these studies provide new insights into the understanding of complex brain functions of participants actively performing ordinary tasks in natural body positions and situations within real operational environments.
Chin-Teng Lin, Li-Wei Ko, Jin-Chern Chiou, Jeng-Ren Duann, Ruey-Song Huang, Sheng-Fu Liang, Tzai-Wen Chiu, Tzyy-Ping Jung
Proc. IEEE2
2007 Classification of Driver's Cognitive Responses Using Nonparametric Single-trial EEG Analysis
abstract
Accidents caused by errors and failures in human performance among traffic fatalities have a high rate causing death and become an important issue in public security. The key problem causing these car accidents is mainly because that the drivers failed to perceive the changes of the traffic lights or the unexpected conditions happening accidentally on the roads. In this paper, we devised a quantitative analysis for ongoing assessment of driver's cognitive responses by investigating the neurobiological information underlying electroencephalographic (EEG) brain dynamics in traffic-light experiments in a virtual-reality (VR) dynamic driving environment. Three different feature extraction methods including nonparametric weighted feature extraction (NWFE), principal component analysis (PCA), discriminant analysis feature extraction (DAFE) are applied to reduce the feature dimension and project the measured EEG signals to a feature space spanned by their eigenvectors. After that, the mapped data can be classified with fewer features and their classification results are compared by utilizing three different classifiers including Gaussian classifier (GC), k nearest neighbor classification (KNNC), and naive Bayes classifier (NBC). Experimental results show that the successful rate of nonparametric weighted feature extraction combined with Gaussian classifier is higher more than 10% compared with other combinations. It also demonstrates the feasibility of detecting and analyzing single-trail ERP signals that represent operators' cognitive states and responses to task events.
Chin-Teng Lin, Li-Wei Ko, Ken-Li Lin, Sheng-Fu Liang, Bor-Chen Kuo, I-Fang Chung, Lan-Da Van
ISCAS2
2006 Driver's drowsiness estimation by combining EEG signal analysis and ICA-based fuzzy neural networks
abstract
The public security has become an important issue in recent years, especially, the safe manipulation and control of vehicles in preventing the growing number of traffic accident fatalities. Accidents caused by drivers' drowsiness have a high fatality rate due to the decline of drivers' abilities in perception, recognition, and vehicle control abilities while sleepy. Preventing such an accident requires a technique for detecting, estimating, and predicting the level of alertness of a driver and a mechanism to maintain the driver's maximum performance of driving. The ICAFNN is a fuzzy neural network (FNN) capable of parameter self-adapting and structure self-constructing to acquire a small number of fuzzy rules for interpreting the embedded knowledge of a system from the given training data set. Our experiments show that the ICAFNN can achieve significant improvements in the accuracy of drowsiness estimation compared with our previous works.
Chin-Teng Lin, Sheng-Fu Liang, Yu-Chieh Chen, Yung-Chi Hsu, Li-Wei Ko
ISCAS5
2006 Development of a Real-Time Wireless Embedded Brain Signal Acquisition/Processing System and its Application on Driver's Drowsiness Estimation
abstract
In this paper, a portable real-time wireless embedded brain signal acquisition/processing system is developed. The proposed system integrates electroencephalogram signal amplifier technique, wireless transmission technique, and embedded real-time system. The development strategy of this system contains three parts: First, the Bluetooth protocol is used as a transmission interface and integrated with the bio-signal amplifier to transmit the measured physiological signals wirelessly. Second, the OMAP (open multimedia architecture platform) is used as a development platform and an embedded operating system for OMAP is also designed. Finally, DSP Gateway is developed as a mechanism to deal with the brain-signal analyzing tasks shared by ARM and DSP. A driver's cognitive-state estimation program has been developed and implemented on the proposed dual core processor-based real time wireless embedded system for demonstration.
Hung-Yi Hsieh, Sheng-Fu Liang, Li-Wei Ko, May Lin, Chin-Teng Lin
SMC3
2006 Driving Style Classification by Analyzing EEG Responses to Unexpected Obstacle Dodging Tasks
abstract
Driving safely has received increasing attention of the publics due to the growing number of traffic accidents that the driver's driving style is highly correlated to many accidents. The purpose of this study is to investigate the relationship between driver's driving style and driver's ERP response. In our research, a virtual reality (VR) driving environment is developed to provide stimuli to subjects. Independent component analysis (ICA) is used to decompose the electroencephalogram (EEG) data. The power spectrum analysis of ICA components and correlation analysis are employed to investigate the EEG activities related to driving style. Experimental results demonstrate that we may classify the drivers into aggressive or gentle styles based on the observed ERP difference corresponding to the proposed unexpected obstacle dodging tasks.
Chin-Teng Lin, Sheng-Fu Liang, Wen-Hung Chao, Li-Wei Ko, Chih-Feng Chao, Yu-Chieh Chen, Teng-Yi Huang
SMC4
2005 Estimating mixing parameters of regularized feature extractions by genetic algorithm
Bor-Chen Kuo, Kuang-Yu Chang, Jinn-Min Yang, Li-Wei Ko
IGARSS4
2005 An Optimal Nonparametric Weighted System for Hyperspectral Data Classification
Li-Wei Ko, Bor-Chen Kuo, Chin-Teng Lin
KES (1)1
2004 A two-stage feature extraction for hyperspectral image data classification
abstract
In this study, a two-stage feature extraction algorithm cooperated with feature selection is proposed for improving hyperspectral data classification. The first stage feature extraction extracts the features for separating all classes and second stage feature extraction extracts the features for separating individual pair of classes, which cannot be well separated in first stage feature space. Then, feature selection is applied for selecting the best features. Real data experimental result show that the proposed 2-stage feature extraction outperforms single stage feature extraction
Guey-Shya Chen, Li-Wei Ko, Bor-Chen Kuo, Shu-Chuan Shih
IGARSS2
2003 Regularized feature extractions for hyperspectral data classification
Bor-Chen Kuo, Li-Wei Ko, Chia-Hao Pai, David A. Landgrebe
IGARSS2