Current network management needs an end-to-end overview of various connections rather than the information that is purely local to the individual devices. The typical manager-centric polling approach, however, is not adequate to understand network-wide behavior of a large-scale broadband network. We propose a new management information base (MIB) approach, called operation, administration, and maintenance (OAM) MIB. The MIB provides a network manager with dynamic end-to-end management information by utilizing special standard ATM cells. The MIB makes end-to-end management feasible while it reduces management-related traffic and manager-to-manager interactions. In our model, a customer network management system accesses the MIB through M1/M2 reference points of the ATM Forum management architecture with simple network management protocol (SNMP).

A QoS restoration scheme for VP-based ATM networks is proposed and its related characteristics are evaluated. The proposed scheme is a state-independent restoration scheme using a disjoint path group. A VP assignment and capacity planning problem using a disjoint path group are formulated. When a failure occurs, failed working VP are switched to protection paths with the same QoS level using a simple and fast restoration algorithm. The simulated restoration characteristics of the proposed algorithm are presented. A scheme of excess capacity assignment to a protection path for dynamic traffic demands is also presented and analyzed.

Generally, weld bead shape is a serious factor in falling-off in weld quality among various kinds of weld defect. In GMAW, weld bead shape affects a number of welding parameters including; welding current, voltage, speed and weaving length. To detect weld bead shape, we select proper welding parameters. We have difficulty analyzing the relationship between weld bead shape and welding parameters due to non-linearity of the welding process. In the case of an arc sensor, though it has a signal processing problem, it is still a widely-used method in industry because it is low cost and easily automated. Proper welding parameters were selected and a weld bead shape detecting system was proposed, using neural networks which were able to identify the relation between weld bead shape and the welding parameters. Also, in the neural controller, the time delay neural network (TDNN) was used in this proposed neural network, due to non-linearity of the welding process. Besides, in welding quality testing, it is important to analyze the weld bead shape. Proper welding parameters and fifteen points that represent weld bead shape were selected, and a real-time monitoring system of weld bead shape was proposed to find the effects of various welding parameters and estimate weld quality using neural networks.

Generally, though we use a vision sensor or arc sensor in the welding process, it is difficult to define the welding parameters which can be applied to weld quality control. The important parameters in arc welding are arc voltage, welding current, welding speed and they affect the weld bead shape, the stability of the welding process and weld quality. Therefore, it is difficult to determine the unique relationship between the weld bead geometry and the combination of various welding conditions. Due to the various difficulties, we intend to use fuzzy logic and neural networks to solve these problems. Therefore, the combination of fuzzy logic and neural networks has an effect on removing the weld defects, improving the weld quality and finding the desired weld bead shape. Finally, this system can help us make an estimate of the weld bead shape and remove the weld defects.

Asynchronous transfer mode (ATM) network management is an urgent issue for the fast and successful proliferation of ATM networks. Especially, performance management of ATM virtual connections is urgently required because a different quality of service should be guaranteed on each connection. In most cases, the customer's virtual connections traverse multiple subnetworks, therefore, performance information related to specific user connection is distributed in the networks. This makes performance management of ATM network more difficult. In order to obtain this distributed performance information with current ATM-related management information bases (MIBs), interactions among managers and frequent polling of switches are inevitable. This frequent polling and manager to manager interactions may cause management traffic and data retrieval time to increase. In this article, we propose a performance management method using OAM MIB. The MIB is a set of managed objects which have the information provided by OAM (Operation Administration and Maintenance) cells. The basic concept and structure of the MIB are similar to the RMON MIB. By using the OAM MIB, management traffic and manager to manager interactions are much reduced. In our model, customer network management system (NMS) accesses the MIB via M1/M2 reference points of the ATM Forum management architecture with simple network management protocol (SNMP).

In this presentation, we introduce a fast restoration scheme against a link or node failure. Specifically, we apply this scheme to VP (Virtual Path) restoration in ATM (Asynchronous Transfer Mode) networks. Proposed restoration scheme operates on VP-based ATM network. This scheme is a distributed algorithm performed concurrently by network nodes neighboring failed node or link. When a node or link fails, restoration is performed according to the pre-assigned local, regional, and end-to-end restoration scheme. For this, we assigned a restoration level to each network nodes and VPs, respectively. Also, we devise and construct a VP loop, and fast restoration is performed along this loop. This loop is expanded when a failure occurs, and this expanded loop is used for the restoration of the failed VP connection. We define the required VP loop architecture, restoration messages, and restoration procedures. Proposed algorithm is simulated and compared with general flooding restoration scheme. Results show that the proposed loop-expanding restoration scheme can achieve fast restoration goal with a lower burden to network.

This paper proposes a new scheme for an ATM OAM performance management function, hybrid performance management scheme. The performance management OAM function monitors network performance using OAM cells and executes mechanisms to prevent traffic congestion with relation to traffic control functions. For this purpose, the proposed scheme enables the switching system to perform different performance monitoring mechanisms according to the OAM management boundary of end-to-end or segment definition and also makes it possible to provide the detail information in traffic control functions detail.

Generally, when we control the robot, we should calculate exact inverse kinematics. However, inverse kinematics calculation is complex and it takes much time for the manipulator to control in real time. Therefore, the calculation of inverse kinematics can result in a significant control delay in real time. We present a method in which inverse kinematics can be calculated through fuzzy logic mapping, based on an exact solution through fuzzy reasoning instead of inverse kinematics calculation. Also, the result provides sufficient precision and transient tracking error can be controlled based on a fuzzy adaptive scheme. We also demonstrate that neural networks can be used effectively for the control of a nonlinear dynamic system with uncertain or unknown dynamics models and applied to the control robot. The advantage of using the neural approach over the conventional inverse kinematics algorithms is that neural networks can avoid time consuming calculations. We represent a good control efficiency through simulation of a 2-DOF manipulator by fuzzy logic controller, and demonstrate the effectiveness of the proposed learning scheme using feedforward neural networks, too.

Five protocols based on slotted Aloha are proposed for very high-speed optical fiber local area networks using wavelength division multiplexing passive star topology. Each station is equipped with a tunable optical transmitter for data channels, a fixed optical transmitter tuned at a separate control channel, a tunable optical receiver and a fixed optical receiver. To obtain high success probability in the transmission of a control packet determining the transmission of its data packet, the control minislot group is introduced. The performances of five protocols are compared under various system parameters. Numerical results show that the protocols presented have better performance than the corresponding protocols.