Abstract During the past decades, maximum influential location selection (Max-inf) problems have been of intense interest to the spatial database community. The Max-inf problem searches for a location that attracts as many clients as possible, so it is essential to collect the location information of each client for such a query. However, the client location is considered sensitive information, and location privacy has become an emerging issue. To resolve the privacy issue, we present a novel Max-inf problem in a differentially private manner, which is called DP-Max-inf in a road network. Differential privacy is a de-facto standard privacy protection technique that injects controlled noise into statistical query results. In addition, we present the influence region overlapping problem while applying differential privacy to the Max-inf problem using the conventional approach. To remedy this problem, we propose a network Voronoi region-based technique to guarantee query accuracy and a network Voronoi envelope-based pruning heuristic to improve query performance.

In this paper, we describe an optimal network location for travel planning (ONLTP) query, a type of optimal location query. In trip planning, finding the optimal point for a group of users is a fundamental problem in spatial group query processing. Many previous studies have considered the problem of finding the optimal point. However, their queries using an exact method perform efficiently only when the users are closely distributed, not spread out in large road networks. In contrast, approximation methods use two different spatial indices, but they cannot control the trade-off between query performance and accuracy. We propose a method using G-trees [ 1 , 2 ] to remedy these drawbacks. Our exact method is a concrete implementation of the best-first search in G-trees, and our approximation method further reduces the visited nodes of the exact method.

A correction to this paper has been published: https://doi.org/10.1007/s11227-021-03837-x

Digital data are an essential resource for intelligent decision making. As the value of digital data increases, digital markets, where data owner and consumers can deal with data, have also been attracting attention as a means to obtain data. However, the collection of digital data can lead to privacy breaches, which are a substantial impediment that hinders an individual's willingness to provide data. Differential privacy, which is a de facto standard for privacy protection in statistical databases, can be applied to solve the privacy violation problem. To apply differential privacy to the data market, the amount of noise and corresponding data price must be determined; however, this matter has not yet been studied. In this work, we propose a fair negotiation method that can set the appropriate price and noise parameter in the differentially private data market environment. We suggest a data market framework with a market manager that acts as a broker between the data provider and consumer. We also propose a negotiation technique to determine the data price and noise parameter ε using Rubinstein bargaining considering social welfare to prevent unfair transactions. We validate that the proposed negotiation technique can determine an appropriate level of ε and unit price without unfair trade to either the data provider and the consumer.

As the value of digital data increases, the data market is in the spotlight as a means of obtaining a personal information. However, the collection of personal information makes a serious privacy violation and it is a serious problem in the use of personal data. Differential privacy, which is a de-facto standard for privacy protection in statistical databases, can be applied to solve the privacy violation problem. To apply differential privacy to the data market, the amount of noise and corresponding data price should be determined between the provider and consumer. However, this matter has not yet been studied. In this work, we introduce a Privata which is a differentially private data market framework to set the appropriate price and noise parameter in the data market environment. The Privata is based on negotiation technique using Rubinstein bargaining considering social welfare to prevent unfair transactions. We explain the Privata overview and negotiation technique in Privata, and show the Privata implementation.

Digital data on the Web are nowadays regarded significant sources of information for marketing and user profiling, etc. However, digital data are risky sources of privacy violation. To address privacy breaches, we can use differential privacy, which has become the de facto standard for privacy protection in statistical databases. However, problems need to be solved, including those related to noise parameter configuration, even before differential privacy can be applied into the real world. In this study, we introduce a linkage attack to identify a user with different nicknames for each subservice on a hue online portal service. In addition, we propose a configuration technique for the upper bound of noise parameter ε to prevent linkage attack. We demonstrate the linkage attack with experiments by using real-world online portal service data. Finally, we validate the proposed configuration technique.

The number of users who uses location-based services (LBS) which utilize a user's location information to provide beneficial services has been increasing rapidly along with the proliferation of mobile devices such as the smartphone. However, LBS users have expressed concerns regarding their privacy because the collected location information can bring about privacy violations if used maliciously by the LBS provider. Thus, developing privacy-preserving techniques to prevent the exposure of the user's location information is important for the wide application of LBS. Consequently, many researches are being conducted on topics such as location k-anonymity and pseudonym to prevent privacy threats. However, existing research is difficult to apply in real-world LBS because of several limitations such as additional computation and legacy system change cost. In this paper, we propose a P2P architecture to protect the user's location privacy in LBS using personal data storage (PDS) to overcome the drawback in existing techniques. We also introduce a collaborative caching technique, which shares extra query results among users to mitigate performance degradation, that is, for preserving location privacy. Simulation results show that the proposed technique achieves sufficient privacy protection without a trusted third party for anonymization while minimizing system performance degradation.

The increasing number of mobile device users indicates the expansion of personalized location-based services (LBS). Despite their proliferation, the risk of violating users’ privacy by exposing user's location information remains. For this reason, many studies have researched to prevent privacy violation in LBS. However, previous researches only focused on protecting users’ location information without considering semantic location privacy violation through contextual information. In this paper, we explain the process of inferring a user's behavior using semantic information which includes spatial and temporal information. We also suggest a privacy preserving technique to prevent exposure of sensitive behavior in semantic LBS. We implement an android application to validate the proposed technique. In accordance with the experimental results, the proposed b-diversity technique is validated to prevent exposure of sensitive behavior and also minimizing data utilization degradation.

BACKGROUND: The construction of interaction networks between proteins is central to understanding the underlying biological processes. However, since many useful relations are excluded in databases and remain hidden in raw text, a study on automatic interaction extraction from text is important in bioinformatics field. RESULTS: Here, we suggest two kinds of kernel methods for genic interaction extraction, considering the structural aspects of sentences. First, we improve our prior dependency kernel by modifying the kernel function so that it can involve various substructures in terms of (1) e-walks, (2) partial match, (3) non-contiguous paths, and (4) different significance of substructures. Second, we propose the walk-weighted subsequence kernel to parameterize non-contiguous syntactic structures as well as semantic roles and lexical features, which makes learning structural aspects from a small amount of training data effective. Furthermore, we distinguish the significances of parameters such as syntactic locality, semantic roles, and lexical features by varying their weights. CONCLUSIONS: We addressed the genic interaction problem with various dependency kernels and suggested various structural kernel scenarios based on the directed shortest dependency path connecting two entities. Consequently, we obtained promising results over genic interaction data sets with the walk-weighted subsequence kernel. The results are compared using automatically parsed third party protein-protein interaction (PPI) data as well as perfectly syntactic labeled PPI data.

In designing a relational schema, we often consider that an attribute of a table is replicated into other table to reduce the join cost. And such a possible redundancy can be grasped by E/R model (i.e., semantic modeling). Similarly, in mapping XML into relations, we can consider some redundancy to enhance query performance and they can be grasped by the structural traits of DTD (or XML schema). In this paper, we introduce some such practical replication and a tool for efficient management of the replication. Finally, read and update query costs arising by employing the structural redundancy are analyzed experimentally and it is shown that these replication can be very useful.

For the smooth and efficient business within the organization of an enterprise today, it is required to utilize the information processing system by using computers, for which the most important factor for the security of organization is the access control for resources. Many access control methods have been studied including DAC and MAC. The role based access control (RBAC), which is based on role, is spotlighted today, and many models have been studied. However, most RBAC models support the bureaucratic organization structure that is mechanical, static, ordinary and of clear vertical relationships. This paper studies the characteristics of the adhocracy organization and the RBAC model to support the adhocracy organization structure that is organic, dynamic and extraordinary such as matrix organization or task force team.

Database systems for real-time applications must satisfy timing constraints associated with transactions. Typically, a timing constraint is expressed in the form of a deadline and is represented as a priority to be used by schedulers. Recently, security has become another important issue in many real-time applications. In many systems, sensitive information is shared by multiple users with different levels of security clearance. As more advanced database systems are being used in applications that need to support timeliness while managing sensitive information, there is an urgent need to develop protocols for concurrency control in transaction management that satisfy both timing and security requirements. In this paper, we propose a new multiversion concurrency control protocol that ensures that both security and real-time requirements are met. The proposed protocol is primarily based on locking. However, in order to satisfy timing constraints and security requirements, a new method, called the freezing method, is proposed. In order to show that our protocol provides a higher degree of concurrency than existing multiversion protocols, we define a new serializability for multiversion concurrency control, called FR-serializability, which is more general than traditional serializability. We present several examples to illustrate the behavior of our protocol, along with performance comparisons with other protocols. The simulation results show significant performance improvement of the new protocol.

A video server which stores video streams should serve more users with the requested streams rapidly, satisfying their time constraints. For this purpose, the storage system of the video server needs a large disk bandwidth and buffer capacity. However, because the given disk bandwidth and buffer capacity are limited, technologies that utilize effectively the given disk bandwidth and buffer capacity without waste might be needed. We propose the schemes that not only support more users but also maintain the short startup latency by utilizing the disk bandwidth and buffer efficiently which also considers time constraint characteristics of the video stream. When multiple streams are served in the storage system of the multiple disk environment, the short startup latency might be induced by asynchronizing the disk head's moves. If the disk head also moves towards only one side, being based on double buffering, the limited disk bandwidth is saved owing to the reduced disk seek latency so that more streams might be served with satisfying the time constraint characteristics of the streams. The correctness of the proposed schemes is not only analyzed theoretically but also evaluated through simulations.

As the Web server based system is being used more and more, having separate Web servers for each task to distribute the Web server's load are gaining much more popularity over having one main Web server to process all the tasks. When the user tries to access each Web server that contains a number of Web documents that are linked to each other via hyper-links within the domain, each Web server asks the user to follow the verification process even though the user is identical, and this prohibits the user from using the system efficiently. The role based access control method, which is the most suitable access control concept available now for the distributed Web server based system within the domain, is used in this paper. Additionally the method for controlling the level of Web document contents available to the user based on the user's access permission rights is introduced to reduce the granularity of the document content access.

In a legacy operational system, a transaction processing system resolves the data conflicts between transactions by using locks or timestamps. As a result, one of the conflicting transactions should be blocked to resolve the data conflict between the transactions. Queries (or read-only transactions) are not the exceptions. In a query-intensive system such as a decision support system, many data items are read by one query and the length of each transaction is long as usual. If queries execute their operations without being interfered by update transactions, then the system can achieve a higher performance than the existing transaction processing systems. We propose a new transaction scheduling algorithm which eliminates the conflicts between queries and update transactions by using a new version selection scheme, called mark. The mark scheme allows that each transaction has its own version selection point. In the proposed protocol, new version selection rules and an efficient version maintenance scheme is also presented. The proposed protocol is based on a locking scheme and it provides a method to resolve deadlocks caused by locks.

Much research into managing global transactions in multidatabase systems (MDBS) has been proposed to solve problems of ensuring global serializability. In these methods, a few opportunities are provided to the global transaction to execute concurrently. We concentrate our attention on 1) maintaining a consistent database state that is defined by global integrity constraints, and 2) investigation into the more accurate indirect conflict situation so that the global transaction manager (GTM) of MDBS provides a higher degree of concurrency. In this paper, we propose a site-locking concurrency control method in MDBS. In our method more global transactions can be concurrently executed, since the refined boundary of possibility of indirect conflict is offered.

Concurrency control protocols based on multiversions have been used in some commercial transaction processing systems in order to provide the serializable executions of transactions. In the existing protocols, transactions are allowed to read only the most recent version of each data item in order to ensure the correct execution of transactions. However this feature is not desirable in some advanced database systems which have more requirements such as timing or security constraints besides serializability. We propose a new correctness criteria, called F-serializability, for multiversion concurrency control protocols. It is the extended definition of 'l-serial' and relaxes the condition so that a protocol provides not only the most recent version but also the previous one to transactions, if necessary. We prove that whenever a multiversion schedule is F-serializable, the schedule is also one-copy serializable. This is the first contribution of our paper. Next, we propose a new concurrency control protocol for multilevel secure (MLS) database systems which guarantees the proposed serializability. In an MLS database system, a transaction scheduler must satisfy security constraints as well as ensure the serializable execution of transactions.

For real-time database systems, transaction processing must satisfy not only logical consistency constraints but also timing constraints. Conflict serializability is too restrictive to achieve the acceptable throughput and predictable response time. Moreover, serializability may not be necessary for concurrent execution and different correctness criteria may be applied to different applications depending on the semantics and the requirements of transactions. We classify the consistency into six forms and propose a relaxed serializability, called statewise serializability, as the weakest form of consistency in our classification. Statewise serializability alleviates the strictness of serializability by allowing for a controlled inconsistent read operation. It can be properly used as a correctness criterion in real-time database applications. We also present the algorithm that determines whether the schedules are statewise serializable, and compare it to other correctness criteria.

The complexity of real applications in the field of intelligent information systems has required fuzzy data models for the expression and processing of uncertain and imprecise data. We propose a fuzzy association algebra (FA-algebra) as a query algebra for a new fuzzy object oriented data model (F-model). The F-model is investigated as fuzzy extensions of an object oriented data model, in which fuzzy objects and their fuzzy associations are represented. In FA-algebra, fuzzy objects and fuzzy associations are uniformly represented by fuzzy association patterns. As the results of operations by the operators defined in the FA-algebra, the returned fuzzy association patterns contain the truth values which mean the degrees of suitability of patterns as answers for the queries. The completeness of the FA-algebra is shown.

The authors examine a priority-driven locking protocol called integrated real-time locking protocol. They show that this protocol is free of deadlock, and in addition, a high-priority transaction is not blocked by uncommitted lower protocol. They show that this protocol is free of deadlock, and in addition, a high-priority transaction is not blocked by uncommitted lower priority transactions. The protocol does not assume any knowledge about the data requirements or the execution time of each transaction. This makes the protocol widely applicable, since in many actual environments such information may not be readily available. Using a database prototyping environment, it was shown that the proposed protocol offers a performance improvement over the two-phase locking protocol.>