Since Interior Permanent Magnet syncronous Motor has a structure whose magnet is inserted in the rotor, d, q inductance is differ and the motor products hybrid torque combined allignment term and reluctance term. Air gap flux density and d, q axis inductances of the Interior Permanent Magnet Synchronous Motor obtained by analytical method are compensated using Finite Element Method. For optimal design, the efficiency of the motor is taken as the objective function, and Genetic Algorithm finds the value of design parameters which maximize the objective function.

This paper describes the characteristic- analysis and tile optimum design of the single-phase permanent-split condenser motor. The equivalent circuit is constructed by the symmetrical coordinate method and proved its validity by comparing with the experimental data. Then, the numerical optimization technique is applied to improve the efficiency of the motor.

In this paper, tile squirrel case induction motors required multi-objective function are designed. As the objective function of the optimization program, we select the linear combination of loss and mass of motors by using weighting factors. Optimization process is performed by using the evolution strategy (ES). ES is the algorithm that can find the global minimum. To verify validity of the proposed method, a sample design is tried.

전기기계의 설계시에 얻어지는 대형 선형방정식을 풀기 위해서는 엄청난 메모리가 필요하고 계산시간이 요구된다는 점을 고려해야 한다. 병렬계산은 이러한 문제를 해결할 수 있다. 우리는 PVM 환경에서 병렬계산이 가능한 솔비를 설계하였다. 선형방정식을 푸는 방법으로 QMR을 이용하였으며, 수렴속도를 향상시키기 위하여 대각 프리컨디셔너를 사용하였다. 실행 결과는 본 논문에서 구현한 솔비가 실제로 발생하는 문제에 대하여 아주 훌륭하게 동작하는 것을 보여준다.

Hysteresis motor is a synchronous machine which has simple structure and self-start characteristic but also has serious difficulties in numerical analysis. In this study, a finite element analysis for hysteresis motor considering the hysteresis characteristics is presented. The hysteresis model is the magnetization-dependent Preisach model which explains hysteresis phenomena very well. From this, we estimate the instantaneous torque, average torque and hysteresis loss of the rotor, considering slot and winding distribution.

In this paper we presented a calculation method of leakage inductance in electrical machines. For its accurate calculation the finite element method is applied to the analysis of magnetic field distribution. The self and mutual inductances are derived using the results of the magnetic field analysis and the leakage inductance is easily obtained from these inductances. As numerical examples, we tread a single phase transformer and a rotor slot model of induction motor. In the finite element analysis we used the 2D linear magnetostatic formulation with the first-order triangular element.

The analysis of the thin lamination model of the wound core type transformer by FEM requires many region division and much calculationg time, and it has difficulty in calculation by modem computer. A new method which is simulated by a solid but anisotropic block with the magnetic permeabilities in the orthogonal dimension, is selected to account for the presence of the lamination.[1] Based on this equivalent anisotropic block model, we analyze the iron loss of the wound core type transformer by FEM, and compare the simulation results with the experimental results.

The Development of A.C. Induction Motor for Railway Rolling Stock. The traction motor is designed as 4-pole induction motor with self ventilation. The winding insulation is throughout of materials of class C. The rotor is designed as a squrrel rotor with copper bar and casting. The rotor speed is detected by means of a pulse generator. The newer tection motor have no casting(frame). Punched-in holes make up the air duct and transfer the heat losses in complete. Maximim motor rpm is higher due to rotor construction. New is the entry of water-cooled traction motors in urban, However the water cooling design in - unfortunately - not applicable in traction motor.

In this study, we analyzed the transient overvoltage using comparison of lumped and distribution line parameter and compared the results. It is certificated that analysing method is given the same result.

The SRM has high efficiency, a wide speed range, high speed capability and DC-series Motor characteristics. So the SRM has been studied as adjustable speed machine. The speed of SRM can be adjusted to switching angle and exciting voltage. This paper suggests an constant speed drive method of SRM. In this method, the speed is controlled by voltage regulation using PI control and the torque is controlled by advance angle in accordance with, load torque variation.

Permanent magnet brushless motor is widely used in industrial drive applications due to high efficiency, high power ratio, and easy maintenance. Position and speed sensors required in this dolor increase the drive cost, and reduce the application range. Some papers present the sensorless speed control using DSP with a high processing performance. However, DSP increases the cost, and makes the implementation difficult. This study has performed the sensorless speed control with a microprocessor system which can be easily accessed.

A Single-phase condensor motor is analyzed by FEM coupled with external circuit. The finite element analysis is based on the solution of combined equation both the magnetic field equation from the Maxwell's and the circuit equations of the stator and rotor circuit. The external circuit of the single-phase condensor motor to be analyzed is described using FLUX2D and linked to multiple FEM regions. The simulated results show that the condensor motor analysis with external circuit has good agreement with those of test results.

This paper analyzes air gap flux density of the induction motor with the rotor eccentricity and slot effects using Fourier series and FEM. We establishes the validity of results by analyzing the space harmonic order.

In accordance with the development of switching devices, the voltage and current signal have involved the time harmonics. But most power meter is designed to operate in sinusoidal signal. Therefore, this paper evaluate the operating state and characteristic of power meter under the voltage and current included the time harmonics, analysing the results which are obtained by means of theorical analysis and an experiment of several instruments for power measuring.

An efficient technique for the analysis of a general class of microstrip structures with a substrate is applied in this paper using newly-derived closed-form spatial domain Green's functions employed in conjunction with the Method of Moments(MoM). The computed current distributions on the microstrip structures are used to determine the scattering parameters of microstrip discontinuties and the input impedances of microstrip patch antennas. It is shown that the use of the closed-form Green's functions in the context of the MoM provides a computational advantage in terms of the CPU time by almost two orders of magnitude over the conventional spectral domain approach employing the transformed version of the Green's functions.

This paper deals with the magnet for Urban Transit Maglev-01 (Electro-Magnetic Suspension) which is experimented by the static magnet test bed. The test bed is developed for the hinge style. This paper shows the levitation force vs magnet current and difference of the yoke depth.

When LIM is drived by the general purpose inverter, there is no food-back of speed and thrust, etc. Therefore, through analysis of LIM by the simulation, the prediction of operating characteristics and patterns of LIM is necessary. But, the open-loop control system is used widely, because it can consist of simple and cheap. In this paper, we foaled with the dynamic characteristics of LIM drived by V/f constant during acceleration, cruising speed deceleration. And, we compared the simulation value with actual measurement value.

An optimum design method of electric machines using neural network is presented. In this method, two multi - layer perceptrons of analysis and design neural network are used in optimizing process. A preliminary model of linear induction motor for subway is designed by the electric and magnetic loading distribution method and then optimized by presented method.

The main factors to bring out the power failure are trouble and operation power failure, the operation power failure of these includes about 85%. So, it is required that the without interruption of service method reduce the operation power failure. If we develop the without interruption of service method, the operation power failure will reduce greatly. It is necessary to develop the without interruption of service method which it solve various trobles (dissatisfacting solution of customer, sales revenue augmentation, and the reduction of the power failure negotiation work). The results of study are drawing up of the specification for temporary transmission methods, it of the working methods for them, and the scrutiny of the technology contents for them.

This paper presents a new approach to evaluate optimal basic reliability indices of electric distribution systems using genetic algorithm. The use of optimal reliability evaluation is an important aspect of distribution system planning and operation to determine adequacy reliability level of each area. In this paper, the reliability model is based on the analytical method, connecting component failure to load point outage in each section. The proposed method applies genetic algorithm to calculate the optimal values of basic reliability indices, ie. failure rate and repair time, for a load point in the power distribution system, subject to minimizing interruption cost. Test results for the model system are reported in the paper compared with a direct optimization method(gradient projection).

Service restoration has become more important function in the distribution systems. Conventional scheme considers only the single criterion such as margin, switching number and thus lacks the practical power. This paper proposes a new scheme adopting tile fuzzy decision making technique, general ins a more effective restoration plan.

This paper presents an optimization technique using genetic algorithms(GA) for loss minimization in the distribution network reconfiguration. Determining switch position to be opened for loss minimization in the radial distribution system is a discrete optimization problem. GA is appropriate to solve the multivariable optimization problem and it uses population, not a solution. For this reason, GA is attractive to solve this problem. In this paper, we aimed at finding appropriate open sectionalizing switch position using GA, which can lead to minimum transmission losses.

In this paper, the results of development of arrester leakage current detector using micro computer are described. This detector is based on harmonic analysis of the leakage current by FFT. The change of leakage current is the recognized measure of deterioration. For low sensitivity to disturbance, this device used optical fiber. This will be a great benefit of detecting deterioration ZnO arrester.

In performing lightning and fault studies in GISs, it is of great importance to accurately model the conductor network consisting of the grounding systems and overhead conductor structures. In particular, the overhead grounded pipe enclosures of the GIS should be appropriately modelled. In this paper, the overhead pipe enclosures of a 500 kV $SF_6$ breaker and substation grounding system are presented in detail. During a phase-to-ground fault, scalar potentials and electromagnetic fields are computed at different frequencies for various conductor network configurations is defined by varying the number of conductors used to represent the pipes at different frequencies are obtained. Such knowledge will be very useful in reducing computation time for a transient ground potential rise study which will be performed in the future.

This paper describes a computer model of the secondary arc associated with single pole switching scheme to use in system simulation studies. The computer model is based on the mathematical model described by A.T.Johns, et.al[3], and is implemented by the EMTDC which is similar to the Electro Magnetic Transient Program(EMTP). Simulation results using the computer model compare with a previous simulation and field test results.

A technique for power system' stabilization is presented using the variable structure control theory. The selection problem of the proper switching vector is very important subject for a design of the variable structure controller. In this paper, the switching vector is selected by desired eigenvalues allocation. and these desired eigenvalues are determined by eigenvalue assignment. Simulation results show that eigenvalue allocation variable structure stabilizer yields better dynamic performance than the others (conventional PSS, optimal linear stabilizer) and is robust to wide variations of the system parameters.

This paper presents a design technique of the fuzzy PID controller for power system stabilization. PID parameters of the fuzzy PID controller was self-tuned by the fuzzy inference algorithm. The Nosed controller compare with conventional power system stabilizer(PSS) under various of initial value of rotor angle deviation and load condition. The related simulation results show that the Nosed controller was more excellent control characteristics than conventional PSS in transient-state and steady-state response.

This paper describes an extension or a pair or multiple load flow solutions and nose curve method developed for voltage stability analysis or AC power systems to AC/DC systems. In this approach the converters are regarded as voltage dependent loads. Assuming that the converters at the unstable (-mode) solution consume the same power equal to the power at the stable (+mode) solution, the unstable solutions or the nose curves arc determined. This method is very efficient since estimating voltage collapse point and voltage stability margin arc determined by a few iterations of multiple load flow solutions. Also the method has the advantages that since the structure or Jacobian matrix is same with that of AC load flow, modal analysis or voltage stability is readily applicable if desired.

In this paper, the derivation of the energy function reflecting the governor's integral control loop is presented. When integral control is considered we obtain oscillatory response of the loop at the price of reducing frequency error. In other words, as $K_I$ is inclosed, the region of stability is decresed. When derived energy function is applied to the one machine infinite bus system, we showed that this function can be used to assess stability.

In this paper, a good fault location algorithm will be presented, which uses novel signal processing techniques and takes a new paradigm to overcome some drawbacks of the conventional methods. The main feature of the method is that it uses the high frequency components in fault signal and considers the influence of the source network by using a traveling wave concept.

This paper presents a method for the extraction of the fundamental frequency from transient signals using Prony's analysis. There exists transient voltages and current after a fault including an exponetially decaying do component and harmonics as well as the fundamental frequency. As Prony's analysis uses exponetially decaying functions as basis functions it can extract the fundamental frequency precisely from transient signals. The results of comparison with DFT are also shown.

In power system stability analysis, modelling of the synchronous machine is necessary and vary important. In this paper, a synchronous machine is modeled and simulated by using Object-Oriented method. The mathematical equations describing the dynamic behavior of the synchronous machine is represented by block diagram and Objected-Oriented Digital Computer Simulater(ODCS). The developed method is tested for a one-machine-to-infinite-bus system, which is accurate and very useful for a multi-machine system simulation.

This paper presents a new saturation modeling technique of synchronous generators using the operating data. With the stator voltages, currents and the field current directly measured on the field winding at different steady state operating conditions, it can estimate tile saturated stator mutual inductances, stator resistance and the field-stator equivalent turns ratio. Effects of the measurement noises on tile estimated parameters are also investigated.

Now days, voltage stability is well recognized as an important problem. It is well known that voltage stability is influenced by the characteristics of load. Up to present, voltage stability researches were done by the static load modeling, but it is needed that the precise analysis by the view point of dynamic load modeling. In this paper, with induction motor as dynamic load, I show the voltage collapse mechanism followed by load increase. Then I propose the protective method of voltage collapse by using TCSC.

In this study, we formulate production costing problem with environmental and operational constraints into an optimization problem of LP form. In the process of formulation, auxiliary constraints on which reflect unit loading order are constructed to reduce the size of optimization problem by economic operation rules. As a solution of the optimization problem in LP form, we use Karmarkar's method which performs much faster than simplex method in solving large scale LP problem. The proposed production costing algorithm is applied to IEEE Reliability Test System, and performs production simulation under environmental and operational constraints. Test and computer results are given to show the accuracy and usefulness of the proposed algorithm in the field of power system planning.

For an effective application of the cogeneration system for commercial and industrial buildings, we need to develop a relevant model to determine the long-term based optimal sizing of the cogeneration system considering electrical and thermal load demands, buy and sell contracts with electric utility and the annual production cost. In assessing the optimal sizing of cogeneration, we have to consider both economic parameters and their capacity expansion for the increased electrical and thermals demand in the future. In this paper, we propose a mathematical model for the optimal sizing of cogeneration systems considering annual production costs and other economic parameter such as, lifetime of the equipment, time value of the capital, etc. In the case study, we thoroughly examine the effects of the economic parameters and determine the optimal size of the sample system. In addition, we calculate the payback period of the cogeneration investment.

TCSC can not only increase power flow but also damp low frequency oscillation by controlling firing angles of thyristors. But, a model considering voltage, current firing angles is not derived. This paper used a small signal model considirng these variables which was derived in paper [1]. TCSC model is combined with swing equation. Being related to rotor angles and firing angles of thyristors, current and synchronizing torque coefficient is reformulated. Because firing angles of thyristors can be controlled only twice within one period, swing equation is transformed to discrete time model. It is shown that low frequency oscillation can be damped by controlling firing angles in one machine infinite bus power system.

This paper describes the optimal operation scheduling technique using genetic algorithms on cogeneration systems with variable efficiency in case of bottoming cycle. Variable efficiency included nonlinear behavior is obtained by least square method based on the real data of industrial cogeneration systems. Genetic algorithms is coded as a vector of floating point numbers. The results of simulation are evaluated that the genetic algorithms can be applied to perform the operation scheduling.

This paper presents the optimal operation scheduling on cogeneration systems connected with auxiliary equipment by using the possibility fuzzy theory. The probability fuzzy theory is a method to obtain the possibility of the solution from the fuzzification of coefficients. Simulation is carried out to obtain the boundary of heat production in each time interval. Simulation results shows effectively the flexible operation boundary to establish operation scheduling.

This paper presents a functional ability improvement of auto-reclosing relay in the power transmission line protection. When the high speed auto-reclosing is successful, Auto-reclosing is practically valuable to improve the transient stability limit of a power system, but it is fail due to surviving fault, both electrical and mechanical stresses can result on the transformers and turbine-generator. It is true that the longer dead time of the reclosing relay gives the higher rate of successful reclosing, On the other hand, the power system does not always need high speed reclosing because of enough stability margin. This paper proposed "stability margin based dead time reclosing" in order to decrease not only the rate of unsuccessful reclosing, but the possibility of the harmful stress also. On-line transient stability assessment using artificial neural network, for implementing the proposed scheme, has studied and tested with resonable results.

In this paper, we proposed digitalized low cost data logger system. In the past, data logger system which use analog method had many problems, inconvenience of measurement, unsatisfied accuracy, and had difficulty in storing data. Proposed system overcome these problems by using one-chip microcontroller which detects abnormal satus and saves it in RAM card. Saved data are transmitted to personal computer by serial communication port and by parallel interface card. Field experiment results validate the performances of the proposed system.

This paper is to develop a measurement system of the displacement distance using ultrasonic sensors. Two 400KHz ultrasonic sensors are used for realizing the measurement system, such as one sensor transmits the sine wave and the other sensor receives this wave. The displacement is measured by the phase difference between transmitting and receiving signals. A phase defecter transforms phase difference to voltage. Because the output voltage pattern has nonlinear characteristics, the relations of the voltage and the distance are learned by a neural network. As the results of teaming, the efficiency of measurement system is improved. This system can measure the displacement distance at the accuracy of 1 micrometer level.

A CFAR algorithm for weibull clutter is discussed. The Maximum a posteriori(MAP) estimator for two parameters(skewness and scale) of the weibull clutter is proposed, assuming the probability density function of skewness parameter is known. And proposed MAP estimator is compared with the Maximum likelihood(ML) estimator. Using this MAP estimator, we can design CFAR detector which is shown to have smaller CFAR loss than ML CFAR detector by the statistical simulation method.

In this paper, wavelet transform with multi-resolution property is used to improve the accuracy of pitch estimation of speech signal. Pitch detection of speech signal is based on the local maxima by using wavelet transform. The wavelet transform of a signal is a multiscale decomposition that is well localized in space and frequency. The proposed pitch defection algorithm is suitable for both low-pitched and high-pitched speakers.

The effect of a periodic and a chaotic' behaviour in the Bonhoeffer-Van der Pol(BVP) oscillation of the nerve membrane driven by a periodic stimulating current $A_1=cos\;{\omega}\;t$ are investigated by numeric analysis and hardware Implementation. To control the chaotic motion, we are suggested by temperature parameter c, $c=c(1+\eta\;cos\;{\Omega}\;t)$ which the values of $\eta,\;Omega$ varied respectively. The feasibilities of chaotic and periodic phenomena were analysed by phase plane and time series.

Neural networks potentially offer a general framework for modeling and control of nonlinear systems. The conventional neural network models are a parody of biological neural structures, and have very slow learning. In order to emulate some, dynamic functions, such as learning and adaption, and to better reflect the dynamics of biological neurons, M.M.Gupta and D.H.Rao have developed a 'dynamic neural model'(DNU). Proposed neural unit model is to introduce some dynamics to the neuron transfer function, such that the neuron activity depends on internal states. Numerical examples are presented for a model system. Those case studies showed that the proposed DNU is so useful in practical sense.

This paper introduces an identification model called the Dynamic Neural Network(DNN) with a multilayer neural network in the forward path and a linear dynamical system in the feedback path, and defines Dynamic BackPropagation(DBP) as a learning algorithm for it. This identification model uses the feedback of its own output as a learning signal, which is not affected by a noise added to the output terminal of the plant so, it can be considered as a parallel identification model, and when compared with a series-parallel model which does not use the concept of the feedback, the proposed identification scheme exhibits more robust performance.

The recent rapid growth of air conditioning load has become a major reason of peak load increase in summer. In connection with this, we surveyed the load management projects of utilities world-wide and their detailed activities. This study is to develop a remote load control system using computer and radio communications. We finished the field-test of this system on August 1995 in Seoul area. During the field-test, the remote load control of air conditioners was proved to be well-timed. Two control modes, group control and all control, are available for the user to select. The transmission reliability of the load control signal was very good and the functions of system hardware as well as the software were excellent. So we confirmed the applicability of the load control system including the paper communication network. In this paper, detailed information on the system functions and experimental results are described.

Automatic control equipment in hydro power plant, such as turbine governor or automatic voltage regulator have to act promptly against for variation of power system, so it is necessary to check and test continuously. During last five years, the performance test of automatic control equipment was performed about 20 units of hydro turbine generator. In this process, because it has complex connection and before calibration, signal conditioner was developed as an auxiliary equipment for performance test. It includes function of signal amplifier, transducer, and meters. As a result of use this equipment for electric governor test at soyang-gang hydro power plant, it was possible to find output data equal to old one.

About a half of Electric power is generated by nuclear power plants in korea. So, the stable operation of nuclear power plant is very important for suppling the essential national electric power. A S/G(Steam Generator) level control is the most difficult system in PWR(Pressurized Water Reactor) nuclear power plant. Because of the non-linear and the non-nominal response of S/G level control, it Is very difficult to control the level by automatic mode or manual mode. The goal of this study is to establish and verify a advanced control algorithm by analyzing, modelling, stability calculation, controller parameter calculation, simulation for S/G level control system.

The sensor signal validation and failure detection system must be able to detect, isolate, and identify sensor degradation as well as provide a reconstruction of the measurements. In this study, this is accomplished by combining the neural network, the Generalized Consistency Checking(GCC), and the Sequential Probability Ratio Test(SPRT) method in a decision estimator module. The GCC method is a computationally efficient system for redundant sensors, while the SPRT provides the ability to make decisions based on the degradation history of a sensor. The methodology is also extended to the detection of noise degradation. The acceptability of the proposed method is demonstration by using the simulation data in safety injection accident of nuclear power plants. The results show that the signal validation and sensor failure detection system is able to detect and isolate a bias failure and noise type failures under transient conditions. And also, the system is able to provide the validated signal by reconstructing the measurement signals in the failure conditions considered.

In this paper, on-line adaptive friction compensation scheme for the precise position control is presented. 2 DOF system with compliance and friction is used for the plant model. In order to reduce the calculation time for the parameter estimation, 1 DOF estimation model is used. The computer simulation and experimental results show the validity of the supposed scheme.

The travelling ultrasonic motor(USM) has good some characteristics over conventional servo motors such as compact size, light weight, silent moton, high torque and high speed response. The USM is driven by 2-phase AC electricity. By adjusting the phase difference of the motor power we control rotation, speed and torque of USM. In this paper, we propose design method using PLSI(programmable Large Scale Integration) of USM controller to adjust the phase difference of the motor power. As compared the previous, the new controller has some advantage that high speed, predictable performance, low power and so on.

In this paper, Cross-Coupled Controller proposed for multi axes servo system. Tracking error and contouring error exist when a machine tool moves along the trajectory in multi exes system. The proposed scheme enhances the contouring performance by reducing contour error. Feedforward compensator reduces the effects of a nonlinear disturbance such as friction or dead zone. The proposed control scheme reduces the contour error which occured when the tool tracks the reference trajectory. Simulation results show that this scheme improves the contouring performance along the reference trajectory in XY-table.

This paper proposes a design of self-tuning fuzzy controller based on evolutionary computation. Optimal membership functions are found by using evolutionary computation. Genetic algorithms and evolution strategy are used for tuning of fuzzy membership function. An arbitrarily speed trajectory is selected to show the performance of the proposed methods. Experiment results show the good performance in the DC motor control system with the self-tuning fuzzy controller based on evolutionary computation.

An improved filter for tracking a maneuvering target is presented. The proposed filter consists of two kalman filters based on different dynamic models and double decision logic. The use of double decision logic for the maneuver onset and ending detection leads to reduction in estimation error. This decision rule is based on evidence theory, Dempster-Shafer theory, which is extended in order to be applicable in the tracking problem. Simulation results show that the proposed filter performs better than IMM at a lower computational load.

Most of the theorems of nonlinear stability is based on the Lyapunov stability theory. The Lyapunov function method is the most well-known and provides precise and rigorous theoretical backgrounds. However, tile conventional approach to direct stability analysis has been performed without taking account of damping effects. For accurate stability analysis of nonlinear systems, it is required to consider the damping effects. This paper presents a new method to derive a group of Lyapunov functions to reflect the damping effects by considering the integral relationships of the system governing equations. This method tan be utilized as a powerful tool to determine the region of attraction.

In the conventional $H_2$ design of PI controllers, the quadratic cost function includes only the plant output term and hence, the optimal controller often results in a very large plant input. In this paper, $H_{\infty}$ design methodology is combined with the conventional $H_2$ design to make a trade-off between the regulation of the plant input and the plant output in a systematic way.

In this paper, we heat 12 blood vessels which are ends of limbs of a body and measure the time for the patient to feel the pain. Using the time data and the fuzzy rule base, we implement a diagnosis system which can informs the present condition of the patient. It is shown by experiments that the proposed diagnosis system yields reasonable results and it can be easily utilized by beginners.

The PID controller is widely used due to its fast response and robustness. But its performance is not so good compared with modem controllers such as adaptive, robust, fuzzy, neural controller. Therefore, it is natural to replace PID controller by modem controllers. But, the problem is that modem controller can not be easily applied to the real time process. Hence, this paper proposes such a structure that PID controller and Self-Learning Fuzzy Controller(SLFC) are in parallel with each other. The parameter of SLFC will be updated by gradient descent method using neuro - identifier. The usefulness of this hybrid controller will be proved by simulation results.

Its is proposed that a stable adaptive control system composed of a fuzzy and a compensating controller, is designed to control nonlinear systems. In fuzzy and proposed compensating controller, parameters of membership functions characterizing the linguistic terms change according to some adaptive law. The adaptive law are based on the Lyapunov systhesis approach. the closed-loop system using the adaptive control structure proposed in this paper is globally stable in the sense that the Lyapunov function decreases as time goes. the following simulation shows the results.

This paper is concerned with a coplanar pursuit-evasion game of one inertial evader and two identical noninertial pursuers. The terminal time is fired and the payoff is the distance between the evader and the nearest pursuer when tile game is terminated. The value functions and the strategies is constructed for all the game surface. To get a value function, we use the generalization of the Bellman-Isaacs fundamental equation.

This paper presents the concepts developed to propose Distributed Control System(DCS). To achieve adequate satisfaction under various conditions, the DCS should be designed from two points of view of functions distributions and performance planning. Performance evaluation criteria can be specified by the response time between units and the utilization of each unit. One has to also consider the ease and the cost of installation, maintenance, repair. Based on these characteristics, different system configuration can be evaluated and compared through results about evaluation criteria in order lo select the best DCS for particular process. The results, in abbreviated form, of the simulation DCS controlling a CAL(Continuos Annealing Line) plant of iron process ate presented.

This paper proposes a model for simulation and performance evaluation of distributed computer systems(DCS). The model is composed of operating system(OS), resource, task, environment submodel. Task Flow Graph(TFG) is suggested to describe the relation between tasks. This paper considers task response time, the scheduler's ready queue length, utilization of each resource as performance indices. The distributed system of Continuous Annealing Line(CAL) in iron process is simulated with the proposed model.

This paper deals with 3-dimensional missile guidance law. This presents the general optimal solution of the state equation which includes the target maneuvering as the Gauss-Markov processing. The main results ore about the transformation between the Cartesian coordinates on which both the guidance law and the filter are bused and the polar coordinates system in real missile guidance and measurement information. And the extended Kalman filter and adjustment of the estimated target acceleration by triangular functions is proposed solution to this transformation problem. It is shown that this proposed transformation is valid in real 3-dimensional guidance problem by the computer simulation.

An object detection algorithm using a modified IDM(Image Differential Method) is proposed for detecting an object in a level crossing area. The conventional object detection method using LASER light has the deadzone that it cannot detect small objects, while the object detection method using image data in a level crossing area can detect such small objects. But the image data in a level crossing area can be changeable easily because the data is outdoor and sensitive to such surrounding environments as the change of the sun beam, the shadow of cars, and so on. So we resolve these problems by adding the normalization and the process for shadow of the image data in a level crossing area to the basic IDM(Image Differential Method).

The main purpose of this paper is to develop the greenhouse control system by PLC in order to dismiss the subject which sequence control system has. The result of this research will contribute to the competitive agriculture product by offering versatile and tow cost greenhouse control system.

The demands of minimizing the reactive power and reducing. the current harmonics are increasing nowadays. The inverter airconditioner needs high power and it operates with wide load range. Conventionally, ah huge LC passive filter is used in airconditioner to improve the P.F and to reduce current harmonics which doesn't gives good results. In this paper, a design of active power factor correction(PFC) circuit for inverter air conditioner is described. To improve the P.F and to reduce the THD, an average current controlled active PFC is designed and tested. Experimental results show that the developed system achieves almost unity P.F and low THD for all load range.

In this paper, a new Maximum Power Point Tractor (MPPT) using Fuzzy Controller is proposed to improve energy convention efficiency. Temperature compensation effect means the photovoltaic voltage is change in condition irradiation, temperature and etc. Fuzzy algorithm is applied to control Boost MPPT converter by Temperature compensation effect. Temperature compensation range is $-40\sim+100^{\circ}C$.

In this paper the multiple three rectifiers for the power factor correction are proposed, analyzed and designed. The multiple three phase rectifiers draw sinusoidal ac currents from the ac voltage sources with nearly unity input power factor and operate with PWM making the control circuit simple and system cost low. Outstandingly it reduces the rated power capacity of devices and the input filter size by reducing input current ripples. Moreover design rules can be obtained from input and output current equations. With the proposed rules, input power factor and output power capacity are determined approximately. Finally these design rules are verified with computer simulations.

This paper proposed a partial resonant swtiching three-phase high power factor converter using a lossless snubber. The proposed converter has a merit of simple controlled circuit because tile input current control discontinuously. And it is improve to input power factor that the snubber capacitor's energy regenerate to the AC source side. This topology is reduced a current/voltage stresses of resonant devices in addition to a partial resonant strategy. The result of simulations with the proposed topology included in this paper.

The proposed GTO converter system has the better harmonic characteristics, especially, in the distortion factor (55%), than the conventional 12-step converter system. The improved harmonic characteristics was achieved through the unsymmetrical angle control of the each converter. In addition, the proposed system can save the cost (20%), spase (50%) and weigh (8%). The proposed system was studied in simulation and experiment.

Many new electronic products are required to have a unity power factor and a distortion free input current waveform. In this parer, a high performance single phase AC/DC converter with input power factor correction is proposed. And each parameters are determined. Proposed control strategy has many advantages which include two Quadrants operation, simplified control circuit, high performance features and continuous Input current. The experimental results are included to verify the validity of this approach.

This paper deals with the voltage unbalance of DC link voltage in series connected two 6-step inverters with double chopper preregulator. Each output of the 6-step inverter is connected to each transformer. The secondary windings of one of the transformers is zig-zag connected and the other star connected. The secondary terminals of the two transformers are series connected which makes 12-step output voltage waveform. In this case, the characteristics of the two transformers are rather different each other. The difference results in the voltage unbalance of the two 6-step inverter input capacitor voltages which make the DC link voltage. The degree of the voltage unbalance is analysied with the variations of load power, load power factor and % impedance of the transformer.

The continuous sliding mode controller with disturbance observer for the tracking control of permanent magnet synchronous motor(PMSM) is presented. In spite of the robust performance of variable structure control, there exists an undesirable chattering problem, which may be very harmful in some cases. To alleviate the problem, continuous sliding mode controller with continuous saturation function is proposed and also the prescribed performance can be obtained by efficient compensation of disturbance. Experimental results using 7.5 kW, 4000 rpm motor which is controlled by TMS320C30 DSP, are shown to demonstrate the usefulness of the proposed algorithm.

In indirect vector control, if the value or the rotor tine constant used in slip calculation is different from the actual rotor time constant because of the temperature rising and flux saturation level, model flux angle and actual flux angle is different so that the transient and steady state response is degraded. In this paper, flux deviation angle is calculated by using actual torque and reference torque, and this flux deviation angle is summed to slip angle, therefore rotor flux angle is always accurate and indirect vector control is satisfied.

In crane drives, DC motor has been most widely used due to simple control characteristic and favorable transient behavior. Nowadays, however, the squirrel cage induction motor is known as an attractive candidate due to elimination of all sliding electrical contacts, resulting in an exceedingly simple and rugged construction. Especially, in hoist application, the smooth torque control and four quadrant operation are essential. In this paper, an operation of dual inverters with common DC bus fed by vector controlled induction motor is described. Single DSP is employed as a main processor to control dual inverters and communicates each input/output signal with PLC. As well as giving a detailed expression, full simulation and experimental results are presented.

This paper proposes the efficiency improvement method of vvcf-induction motor drives, which operates always at rated speed, regardless of load conditions, with counter emf estimation. The counter emf is estimated by detecting the fundamental component of motor input current, which is employed in speed control algorithm through the comparison with the actual counter emf during the nonconduction interval. The input power reduction by speed control is confirmed through simulations and experimental results.

The non-ideal elements inherent in all categories of AC drives have a significant influence on the performance of speed control. For the high performance of speed control, these non-ideal elements must be considered. This paper discusses the side effects of non-ideal elements such as the offset current of A/D converter, asymmetry of motor and so on and proposes simple compensation methods which are also applicable to any kinds of the motor drive systems. In the experimental results, it is observed that the proposed compensation methods improve the performance of speed control.

A new improved excitation control system for power plant synchronous generators has been developed by KEPRI(Korea Electric Power Research Institute). In this paper a description of the developed control system with detailed design concept is given. Field tests are conducted to show the system performance and to obtain the model parameters. Based on the measurement approached by field tests excitation model parameters supposing a mathmatical model is given can be determinded. This paper also proposes a algorithm of parameter estimation and identification in the synchronous Generator Excitation Control System.

Deadbeat controlled PWM Inverter is realized. This PWM inverter performs the instantaneous control method which is based on the real-time digital feedback control and the microprocessor-based deadbeat control. For the deadbeat current controller, the system's order becomes a high order and increases computation delay time. Therefore, The delay tine produces current ripple. To minimize the current ripple, a new method based on deadbeat control theory for current regulation is proposed. It is constructed by a reduced-order state observer which predicts the output current in next sampling instant.

The most common for starting a single phase induction motor is to install a starting condenser and a centrifugal switch in series with the auxiliary winding. Though this method is simple, life of single phase induction motor is short because of malfunction of a starting condenser and a centrifugal switch and efficiency improvement has limitation. In this paper, the starting characteristics of SPIM is improved by voltage and phase control strategy of auxiliary winding in removing a starting condenser and a centrifugal switch. Finally, the excellent starting performance of SPIM is shown through simulation and experimental results.

In this paper, We applied the $\mu$-stepping method on the Phase Excitation Sequence of Hybrid type LPM. Linear Pulse Motor can opeate in an open loop control as an effective positioning actuator. PWM driver was used for low power loss and automatically adjusted voltage at rate current. Finally we find that through the position-velocity for timing Triangular and Trapezoidal Profile are very affected by velocity and acceleration parameter.

In this paper, the regenerative braking control system for 4 WD Electric Vehicle (EV) is proposed. Many studies on efficient drive of EV are being done to prolong the one charge distance. By using the regenerative braking (REGEN), the resulting EV system has following advantages : a) battery is recharged with the mechanical energy of EV, b) the running load can be reduced, and consequently the efficiency can be increased. The problem of REGEN that the power acceptance ability of battery is limited can be solved by controlling regenerative braking torque. The proposed control system has following characteristics. : a) It controls regenerative power by varying mechanical braking torque. b) It controls mechanical braking torque using load torque observer. c) It controls the regenerative braking torque independently. The control scheme and simulation results are presented for the experimental car.

In this article a fuzzy controller and neural network adaptive observer is proposed and applied to the case of induction motor control. The proposed observer which comprises neural network flux observer and neural network torque observer is trained to learn the flux dynamics and torque dynamics and subjected to further on-line training by means of a backpropagation algorithm. Therefore it has been shown that the robust control of induction motor neglects the rotor time constant variations.

This paper proposes a new filter topology that suppresses the high voltage gradient(dv/dt) in ac motor terminals. The high voltage gradient(dv/dt) causes over voltages on the motor windings, the degradation or motor insulation, and the bearing failure. Moreover surge voltage with high voltage gradient(dv/dt) in the PWM inverter red drive system where long line cables are required causes more serious problem to the motor. Thus, the most advisable method is attaching output filter to the inverter output terminals. The conventional output filters have several problems such as bulky size, difficulty or parameter tuning. The proposed filter can be relatively smaller than the conventional filters. By the proposed filter, the shaping or PWM waveform can considerably suppress high dv/dt in motor feeding cable from the inverter. The effectiveness or the proposed filter is compared with that or the conventional one and is verified by the computer simulation.

This paper represents an overvoltage clamping circuit for three level inverters. With a proposed overvoltage clamping circuit, the problems that high voltage stresses and voltage unbalance between outer and inner switches occurs in high power and high voltage 3-level inverters are reduced.

An improved carrier PWM method for three phase voltage source inverters is proposed. The basic idea of the proposed method is deleting unnecessary 1/3 of switchings in the saw tooth carrier PWM method. The lowest frequency of the remained harmonics of this method (when the modulation index is large) is about 50% higher and the maximum modulated voltage is about 15% higher than those of the triangular carrier PWM method. This method will be useful especially in the linear feedback current control and MOSFET inverters.

In this paper, a binary disturbance observer is implemented, and the validity is verified by experiments. A disturbance observer with binary control is proposed to suppress the chattering of the conventional sliding mode observer in estimation of the external disturbance. As a result of experiments, it is confirmed that the robust and high precision position control is possible by the proposed binary observer.

Recently, a power supply system of the telecommunication equipments with monitoring function has been widely studied. In the power supply system which is apart from the central station, it is required to check and test the operating states of the system at the central station. In this paper, the power supply system with monitoring function is discussed. In the system, the Full-Bridge converter is designed as a power supply and it has the ratings of DC 280-340V input and DC 48V, 480W output. And the monitoring part of the system is composed of a voltage and current sensing unit A/D converter, I/O card, and a personal computer. The operating states of the system is monitored by checking the voltage and current variation at input and output, and it is represented by graphical modes. By conducting the experiment, it is confirmed that the operating states of the system is well monitored.

The base/gate drive suppression method proposed by Joshi and Bose is that which detects the output current polarity of the leg and, according to the polarity, suppresses the base/gate drive of one of the ore switching devices of the leg. This method has the merit that it does not have the conventional dead time problem, reduces the power loss of the driving circuit and others. But this method has difficulty in implementation. In this paper, a new base/gate drive suppression method by detecting not the output current polarity but the output voltage polarity is proposed. The proposed method is easier to implement than Joshi and Bose's method.

This paper proposes two base/gate drive suppression methods of NPC inverters. The first is the output current polarity detection type, which can be regarded as an extension of Joshi and Bose's method for ordinary inverters. But this method has difficulties in implementation. The second is the output voltage polarity detection type, which is easier to implement than the former. The base/gate drive suppression methods have the merit that it does not have the dead time problem, reduces the power loss of the driving circuit, and others.

An Inductively Coupled Plasma(ICP) was employed to prepare the Diamond-Like Carbon film with $CH_4$ gas. We observed the changes of mechanical, optical properties and internal stress of the films according to the variation of discharge power and negative-self bias. When weak magnetic field is applied, the properties of film are observed to change drastically. In magnetized case, the micro-hardness and the internal stress increase up to critical point and droped down in marked contrast to unmagnetized case. It suggests that large amount of ion flux exists due to high dissociation rate of the reactive radicals in plasma with magnetic field as reported elsewhere. As a result of FT-IR absorption measurement it could be confirmed that the $CH_x$ bonding and the micro-hardness and the internal stress decreased with the increase of negative-self bias.

SiC buffer layers were grown on Si(100) substrates by ultra-high-vacuum electron cryclotron resonance plasma (UHV ECR plasma) from $CH_4/H_2$ mixture at 700$^{\circ}C$. The electron densities and temperature were measured by single probe. The axial plasma potentials measured by emissive probe had the double layer structure at positive substrate bias. Piranha cleaning was carried out as ex-situ wet cleaning. Clean and smooth silicon surface were prepared by in-situ hydrogen plasma cleaning at 540$^{\circ}C$. A short exposure to hydrogen plasma transforms the Si surface from 1$\times$1 to 2$\times$1 reconstruction. It was monitored by reflection high energy electron diffraction (RHEED). The defect densities were analysed by the dilute Schimmel etching. The results showed that the substrate bias is important factor in hydrogen plasma cleaning. The low base pressure ($5\times10^{-10}$ torr) restrains the $SiO_2$ growth on silicon surface. The grown layers showed different characteristics at various substrate bias. RHEED and K-ray Photoelectron spectroscopy study showed that grown layer was SiC.

Laser ablation was used to fabricate superconducting $YBa_2Cu_3O_{7-x}$ (YBCO) thin films on metallic substrates with an YSZ buffer layer. An ArF excimer laser with an wavelength of 193 nm was used to deposit both YSZ buffer layer and superconducting thin film. The characterizations of thin films were performed and compared. With a 200 nm YSZ buffer layer, c-axis orientation and $T_c$=85 K were obtained for a 200 nm-thick YBCO film.

In this paper, structual, optical properties of CdTe thin films and photovoltaic properties of thin film CdS/CdTe solar cell prepared by thermal vacuum evaporation were studied. The crystal structure of CdTe films was zircblend type with preferential orientation of the (111)plane parallel to the substrate. The heat treatment appears to stabilize this structure. The result of optical absorption and transmittance show that solar radiation with energy larger than bandgap is almost completely absorbed within an about $2{\mu}m$ thickness of the evaporated CdTe layer and transmittance of the CdTe film was larger with increasing annealing temperature. It was found that CdS/CdTe solar cell characteristics were improved by the heat treatment.

In this study, $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramic thin films were fabricated from an alkoxide-based by Sol-Gel method. $Pb(Zr_{0.52}Ti_{0.48})O_3$ stock solution was made and spin-coated on the $Pt/SiO_2/Si$ substrate at 4000[rpm] for 30[sec]. Coated specimens were dried at 400[$^{\circ}C$] for 10 [min]. The coating process was repeated 4 times and then heat-treated at 500$\sim$800[$^{\circ}C$], 1 hour. The final thickness of the thin films were about 3000[A]. The crystallinity and microstructure of the thin films were investigated for varing the sintering condition. The ferroelectric perovskite' phases precipitated under the sintering of 700[$^{\circ}C$] for 1 hours. In the $Pb(Zr_{0.52}Ti_{0.48})O_3$ thin films sintered at 700[$^{\circ}C$] for 1 hour, dielectric constant and dielectric loss were 2133, 2.2[%] at room temperature, respectively. $Pb(Zr_{0.52}Ti_{0.48})O_3$ thin film capacitors having good dielectric and electrical properties are expected for the application to the dielectric material of DRAM.

The surface properties after plasma etching of Al(Si, Cu) solutions using the chemistries of chlorinated and fluorinated gases with varying the etching time have been investigated using X-ray Photoelectron Spectroscopy. Impurities of C, Cl, F and O etc are observed on the etched Al(Si, Cu) films. After 95% etching, aluminum and silicon show metallic states and oxized (partially chlorinated) states, copper shows Cu metallic states and Cu-Clx(x$CuCl_x$ (x$CuCl_x$ (1

Using piezoresistive effects of single-crystal and poly-crystalline silicon, pressure sensors of the same pattern were fabricated for comparison of temperature characteristics. Optimum size and aspect ratio of rectangular sensor diaphragm were calculated by FEM. For polsilicon pressure sensor, polysilicon resistors of Wheatstone bridge were deposited by LPCVD to be used in a wide' temperature range. Polysilicon pressure sensors showed more stable temperature characteristics than single-crysta1 silicon in the range of $-20\sim125[^{\circ}C]$. To get low TCO (Temperature Coefficient of Offset), below $\pm$3 [${\mu}V/V/^{\circ}C$], it is needed for each TCR of piezoresistors to have a deviation within $\pm25[ppm/^{\circ}C]$ less than $\pm500[ppm/^{\circ}C]$ of resistors for polysilicon pressure sensor can result in low TCS(Temperature Coefficient of Sensitivity) of -0.1[%FS/$^{\circ}C$].

ZnO varistor with composition of ZnO(90wt%)-$Bi_2O_3$(3wt%)-$Sb_2O_3$(3.61wt%)-$CO_2O_3$(1.16wt%)-NiO (0.88wt%)-$MnO_2$(0.71wt%)-$Cr_2O_3$(0.93wt%) according to $Al_2O_3$ addtive was fabricated by sintering methods. The optimal densification were established for the processing conditions of 8000 rpm 190$^{\circ}C$ spray drying and 1200$^{\circ}C$ 2hrs sintering. Then here investigated how additive compotions and processing variables affected the electrical and the phesical properties of these ZnO varistors.

A modified silicon direct bonding method has been developed alloying an intimate contact between grooved and smooth mirror-polished oxide-free silicon wafers. A regular set of grooves was formed during preparation of heavily doped $p^+$-type grid network by oxide-masking und boron diffusion. Void-free bonded interfaces with filing of the grooves were observed by x-ray diffraction topography, infrared, optical. and scanning electron microscope techniques. The presence of regularly formed grooves in bending plane results in the substantial decrease of dislocation over large areas near the interface. Moreover two strongly misoriented waters could be successfully bonded by new technique. Diodes with bonded a pn-junction yielded a value of the ideality factor n about 1.5 and the uniform distribution of series resistance over the whole area of horded pn-structure. The suitability of the modified technique was confirmed by I - V characteristics of power diodes and reversly switched-on dynistor(RSD) with a working area about $12cm^2$. Both devices demonstrated breakdown voltages close to the calculation values.

The optical and electrical properties of High Speed AlGaAs infrared LED by using metal wet etch process instead of metal lift-off process are investigated. The power out increases when metal contact is patterned by wet etch process. Forward voltage and Reverse voltage for metal wet etch process represent higher value than the metal lift-off process. The aging effect of power out also indicates good results with wet etch process. The wet etch process for metal contact reveals reliable LED device properties.

Pt(80nm)/$SiO_2$(150nm)/Si 기판위에 $Ba_{0.7}Sr_{0.3}TiO_3$ 박막을 rf-magnetron Sputtering 방법을 이용하여 기판온도 590$^{\circ}C$에서 33nm 두께를 증착했을 때 비유전율은 268 이었다. 비유전율이 3.9인 $SiO_2$와 비교했을 때 유효 두께인 Tox는 0.45nm 이었다. 누설 전류 밀도는 1.5V 전압을 인가했을 때 $4.21\times10^{-7}A/cm^2$이었다.

PZT powders were prepared by the molten salt synthesis method. The porous PZT specimens were prepared from a mixture of PZT and polyvinylalcohol(PVA) powders by BURPS(Burnout Plastic Sphere) technique. The pulse-echo response of porous PZT transducer with various PVA wt.% were studied. The fall time of pulse-echo response of porous PZT transducer was shorten to that of solid PZT-maded transducer. Therefore, a good transmitting and receiving properties could be obtained. The distance between transducer and reflector was in good agreement both solid PZT and porous PZT fabricated transducer.

High quality $Y_1Ba_2Cu_3O_{7-x}$ thin films have been fabricated by pulsed Nd:YAG laser deposition using an unusual 'off-axis' target-substrate geometry. Various properties of superconducting $Y_1Ba_2Cu_3O_{7-x}$ thin films have been studied systematically as a function of oxygen pressure during the deposition, in both 'on-axis' and the unusual 'off-axis' target substrate geometry. In the 'off-axis' geometry, one can completely eliminate the so-called 'laser droplets' form the thin surface and thus obtain smooth high qualify films. It is found that films with optimum structural and electrical properties are obtained at a lower oxygen pressure range during the 'off-axis' deposition when compared with that required in the 'on-axis' deposition geometry.

We investigated the Electromigration characteristics in Cu alloyed Al line and the effect of Ti/TiN barrier layer on the characteristics. Test structures were fabricated by wafer level and 50% failure times were tested in the condition of j= 2 MA/$cm^3$, T= 300$^{\circ}C$. The reliability of Al line was improved which was 0.5%Cu Alloyed, but Ti/TiN under layer deteriorated the reliability while TiN over layer improved the characteristics.

An SOI LDMOS(Silicon-On-Insulator Lateral Double diffused MOSPET) with a tapered field plate is proposed and investigated in terms of the breakdown voltage and on-resistance using 2-D simulator, MEDICI. The results of conventional SOI LDMOS with a stepped field plate are reported for the comparison. Simulated breakdown voltage of the proposed LDMOS is found to be higher than that of conventional LDMOS since surface electric field can be reduced due to the field plate over the tapered oxide. On-resistance of proposed LDMOS is found to be lower than that of conventional LDMOS by 10%.

This paper mainly, describes the electrical characteristics caused by the change of structure in solid state of specimen by electron beam irradiation of high temperature-low expension type molding materials of power semiconductor element. The experiments on physical properties and electrical characteristics for the specimen irradiated electron beam are carried ont. For the investigation on physical properties, XRD analysis is used. And for the experiment of electrical characteristics, measurement of volumn resistivity is used.

In this part a new window function is used to design a SAW band pass filter. As an example, we selected a 99.9 MHz 20-percent bandwidth 20-dB insertion loss filter and fabricated a device on 128$^{\circ}$ X-rotated $LiNbO_3$. The theoretical predictions of a design sample are compared with the experimental data and are shown to be in good agreement over the operating range.

A method is presented for the design and fabrication of the temperature compensation circuits on the Clark electrodes for measuring the dissolved oxygen(DO) concentration. The discussion includes a method of the sensor interface circuits for the DO sensor. Typical polarograms for the DO probes under test using this sensor circuits are presented. High accuracy over 99 % of the I to V conversion using the proposed circuit is verified. Temperature dependence for the test DO probe is well compensated automatically using the thermistor($2k\Omega,\;25^{\circ}C$) in series with correction resistor in the feedback loop of the op-amp circuit in the temperature range of the 0-50$^{\circ}C$.

Many generating stations in korea are 25 years or more old, and are nearing the end of their planned life. Financial conditions and Site, Environment problems have made approval for construction of new stations increasingly difficult, and extending the life of an existing older plant may be a palatable alternative. Therefore, To determine whether generator rewinds are necessary to achieve an extended life, and Methods are required to estimate the proable remaining life of existing winding, here, We are going to estimate insolation condition through Nondestructive diagonostic test and Aging history tests of generator Stator winding and winding conditions through deterioration characteristics due to Heat cycle.

Electrical properties such as tracking resistance, dielectric constant, $tan\delta$, and volume resistivity, and mechanical properties such as tensile, and strength, and % elongation were measured with the alumina trihydrate filled with EPDM. The results were dicussed in terms of the effect of hydroxyl group. The test results show that the tracking resistance of EPDM improves with the increase in ATH content, whereas volume resistivity, dielectric constant, $tan\delta$ decrease wi th increasing ATH content due to polar nature of ATH. In the charge accumulation characteristics, the homocharge is formed in pure EPDM, and as the ATH content increases in the EPDM compound, the amount of homocharge decrease.

The polymerization rate, chemical structure and optical properties of tetramethyldisiloxane(TMS) have been investigated. The rate of polymerization of TMS films increased nonlinearly with the discharge power. The refractive indices of thin films varied from 1.40 to 1.43 and they also increased with increasing discharge power. Also, the extinction coefficient was about 0.2 and is independent of photon energy.

Using as an alternate of insulating material for outdoor and cable, however, it has still many problems to be solved in the field of material such as resistances of environment and tracking. In this paper, Tracking property of PVC filled with aluminum hydroxide have been investigated by ASTM D 2303 method. It was found that time to track of PVC filled aluminum hydroxide was longer than that of unfilled PVC. Tensile strength and elongation of PVC were decreases increased with aluminum hydroxide contents. On the other hand, Thermegravimetry of PVC decreased. Therefore, the increase of time to tracking breakdown by antitracking additive can be explained by increased degradation temperature of polymer.

The interfacial charge distribution was investigated using PE laminate system. It was found that a proper treatment of the interlace could decrease the amount of charge accumulated at the interfaces. High lamination temperature and long lamination time brought about little interfacial charge. It was also observed that the interfacial charge could be decreased by the addition of chemicals which had charge trap or hopping site.

To investigate the effects of solvent extraction on electrical properties of LDPE, charge distribution, electrical conduction, and FT-IR experiments are carried out for three kinds of LDPE which are same for melt index (MI) and density. The effects of short chains for the charge distribution are quite different. For the electrical conduction, the electrical conduction mechanism remains unchanged, as the solvent extraction temperature is increased.

In this Study, the Electrostatic Coutour Distribution in Polymer Electret Acoustic Sensor is calculated using Finite Element Method. As a result, the Electrostatic Countour Distribution is visualized and the design modification could be processed.

The degradation phenomena according to electrical stress in epoxy composites were studied. The formation of electrets were observed by appling high voltages, 22.9[kW/cm], during 5[hr] to five kinds of specimens for a given mixing rate, and then TSC(thermally stimulated current) values were measured at the temperature range of $-160\sim200[^{\circ}C]$.

Solid Oxide Fuel Cell has advantage of high utility because of having high operation temperature. In case of anode, Ni and YSZ being widly used as anode start materials. But Ni can be sintered during operation because that its operation temperature is very high, so it cause to lower the cell performance. It is very important to control the ratio of Ni to YSZ. In this paper, we studed on characterization of anode by controlling the Ni-YSZ contents.

A superconducting cable is one of the promising methods of undground transmission of high electric power in the future. It is very important that composite insulation system of $LN_2$ and polymer films takes into consideration for application high $T_c$ superconductor. This study is about both the partial discharge and properties V-t in $LN_2$. As result, applied voltage doesn't depend on the radius of non-eroded area but eroded area. And eroded area is observed the formation such as the ring of a tree.

Porcelain insulators have been used for the almost all of the suspension insulators in distribution line. However, Puncture breakdowns in porcelain insulators caused by westing cement between metal fitting and porcelain material. There is little puncture breakdown in Epoxy casting insulator. This paper presents a new design technique for the development of suspension insulator used Cycloaliphatic Epoxy resin. The design was performed on the basis of two conditions (weather conditions for the past 30 years and the existing installation conditions of KEPCO) and was proven of its adaptability by FEM method.

We have studied the effect of the mesogenic core of nematic liquid crystals (NLCs) for polar (out-of-plane tilt) anchoring strength on rubbed polyimide (PI) films. The order of polar anchoring strength for NLCs on rubbed PI films is 5CB > PCH5 > CCH5. This order is the same for all rubbing strengths investigated. From these results, we suggest that the polar anchoring strength strongly depends on the polarizability of the NLCs.

Polymer-coated piezoelectric crystals were applied to analyze response characteristic of organic gases. AT-cut quartz crystal with 9 MHz resonant frequency can measure mass of 1 nanogram. Flow type gas-sensing system was used in this experiment. Flow type gas-sensing system has very simple apparatus and shows very fast frequency response for injection of organic gas. We have made parameter using relaxation ratio of frequency response for organic gas. Consequently, we found that the parameter had no relation with quantity of gas injection and dipping.

PVDF (polyvinylidene fluoride) has at least from known crystalline structure ( ; they are referred to as the $\alpha$, $\beta$, $\gamma$ and $\alpha_p$ phase or forms II, I, III and $IV_p$). In this study, the manufactured PVDF thin films through vapor deposition method had for II ( ; the substrate temperature at 30$^{\circ}C$). The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The very high value of the dielectric constant for high temperature conditioned film is believed to be due to the orientation effect. The loss peak caused by molecular motion of the molecules in crystalline regions.

Langmuir-Blodgett technique offers a convenient and elegant way to organic conducting systems for ultra thin films. In conducting systems based on LB films, TCNQ derivatives have been extensively studied as electron acceptor molecules in a large number of organic conducting systems.[1] A very interesting UV-visible spectra of octadecylviologen-$(TCNQ^-)_2$ was obtained from a methylenechloride and acetonitrile mixture, and from Langmuir-Blodgett films. The ESR characteristics of octadecylviologen-$(TCNQ^-)_2$ were studied to understand conducting mechanism and structure of LB films. The ESR spectra infer that the N-dococylquinolinium-TCNQ LB films has anisotropic property. But octadecylviologen-$(TCNQ^-)_2$ does not show angular dependence. As the temperature increases from 350K to 450K, the ESR signal of LB films becomes sharp. Scanning calorimetry(DSC) of octadecylviologen-$(TCNQ^-)_2$ provides the endothermic reaction temperature of the films, 340K, which corresponds to the temperature, 365K, of the new ESR signal.

In this paper, the effect of alkaline oxides on the humidity sensitivity of $V_2O_5$(2mol%)-doped $TiO_2$(98mol%) was investigated as functions of $Li_2CO_3$, $K_2CO_3$, additives (x= 0.0 mol%, 1mol%, 2mol%, 5mol%, 10mol%). 1. The porosity and total intrusion volume of sample containing 1, 2, 5mol% $K_2O$ was increased, and then those of 10mol% $K_2O$ was reduced again. 2. The humidity sensitivity of samples containing 1, 2, 5, 10mol% $K_2O$ were good generally. Especially the sample containing 5mol% $K_2O$ were the better. 3. the stability of the humidity sensitivity of samples containing $K_2O$ at low and high temperatures is very good.

In this paper, the electron beam with 1[Mrad], 2[Mrad], 4[Mrad], 8[Mrad] and 24[Mrad] is irradiated for specimen experiments on physical properties which is investigated by FTIR, and dielectric breakdown among the electrical characteristics of specimen are carried out. For the dielectric breakdown experiment, external 60 [Hz] AC voltage is applied to specimen with the rising voltage of 3[kV/cm] until dielectric breakdown occured. We made a breakdown experiment under the temperature condition of 50[$^{\circ}C$], 100[$^{\circ}C$], 150[$^{\circ}C$] in the silicone oils of dynamic viscosity of 100[cSt].

It is important to understand tile behaviours of tile high pressure DC glow discharge with a micro gap inside a pixel of the plasmas display panel. We prepared a narrow gap discharge system and have measured electron temperature and density by means of double probe methods in high pressure which was between 100torr and 200torr. And the electrode gap was 7mm. When the pressure varied from 100torr to 200torr, the negative glow was created at a distance less than 1mm from the cathode. And the length of the faraday dark space decreased from 8mm to 5mm. Hence probe measurements was mainly, performed in the region of the Faraday dark space. The dependence of electron temperature and density on the pressure and current density was same with that of the general flow discharge, i.e. as the pressure increased the electron temperature decreased and the density increased. But the spatial electron density distribution in the Faraday dark space was highly distorted because of the effect of high pressure.

The impedance characteristics and plasma parameters were experimentally studied in a weakly magnetized planar type, inductively coupled plasma (ICP) system. Compared with non-magnetized for system higher power transfer efficiency, stable impedance matching, enhancement of plasma density and higher electron temperature can be obtained. Such improvements are mainly due to the excitation of deeply penetrating electromagnetic wave and reduction of radial loss of electrons. In particulary, $SF_6$ (sulfur hexafluride) plasma shows unstable impedance matching in non-magnetized ICP because electronegativity of $SF_6$ effects on plasma characteristics. But, magnetized inductively coupled $SF_6$ plasma shows enough impedance matching stability to be applicable to the polysilicon etching in semiconductor process.

A new optical-resistive voltage divider, which consists of light emitting diode, optic fiber, PIN-photo diode and a high qualify shielding resistive divider, whose total response time is 7.35 [ns], has been obtained. The optical to electrical signal converter was constructed with GaAsP series light emitting diode. The response characteristics have been verified by applying the Marx impulse voltage generator experimentally. Comparing with the performance of conventional resistive voltage divider, the characteristics of the proposed optical-resistive voltage divider are more excellent in step response and less sensitive to electromagnetic interference.

This paper deals with semisphere-type sensor fo measuring the electric field waveforms by lightning discharges. The theoretical principle and design rule of the device are introduced, and also the calibration and application investigations are carried out. From the calibration experiments, the frequency bandwidth of the semisphere-type electric field measuring device ranges from 200 [Hz] to 1.56 [MHz], and the sensitivity of sensor is 0.96 [mV/V/m]. The electric field waveforms produced by lightning discharges were observed for June and August 1995. It is shown that the electric field waveforms produced at the distance of more than 50 [km] include only radiation component.

In terms of a new development on the foundation design of 765kV tower and its applications, a revolutionary turning point comes out through this study in approaching the new concept, what we call "Rock anchor" "Deep foundation" to tower foundation which was officially approved by the full load test. this contents is described of the foundation design and the results of full load test for two types foundation.

The Tree observation technique is being highlighted as a research area for deterioration of insulation because of high-voltage power system. For the measurement of tree, image processing is actively studied as a experimental technique of electrical tree, because the conventional directed visual method is impossible to analyze on tree degradation area and tree pattern. In this paper, we have developed the tree measuring system using image processing. By using an image processing technique, the treeing can be easily measured and effectively observed.

In electrostatic airclean filter, the collection efficiency defends on particle charge in the ionizer section. The effect of electrostatic airclean filter condition (deposition of dust, variation of corona discharge current) on corona discharge characteristics was well studied. However, it seems not to be studied on corona discharge characteristics of electrostatic airclean filter respect to contaminated electrode which is caused by practical use. In this paper, Long-term(60days) effects are studied experimentally by two methods. The one is ozone concentration, the other is collection efficiency. Generation of ozone level was increased but collection efficiency was slightly reduced in long-term used electrostatic airclean filter.

This paper describes a diagnosis of power transformers by on-line detection of ultrasonic signals. Partial discharge in power transformer generates ultrasonic signals. The trend of the ultrasonic signal number can be measured when partial discharge is generated in HV Winding. The trend of the ultrasonic signal number could easily be distinguished by taking moving average. The insulation failure due to partial discharge in transformers can be predicted based in the trend analysis of the number of ultrasonic signals caused by partial discharge.

An omegatron mass spectrometer was designed and fabricated. Experiments have been performed to demonstrate the instrument's operation in the ECR plasma device. By using this analyzer, mass spectra have been obtained in hydrogen plasmas, and typical results are presented. In the plasma omegatron, downstreaming plasma generated by ECR are entering the analyzer through a smsll floating aperture. We employ a biasing technique to reduce the ion velocity along the magnetic field and to keep the ions from drifting to the side pintos, and thus achieved improved ion collection and sensitivity. Mass spectra obtained show that main positive ion components are $H_3{^+}$ and $H_2{^+}$ with the density ratio of $H_2{^+}$ to $H_3{^+}$ $\simeq$ 0.2.

In this paper, experiments were carried out to study the decrease of NOx in simulated flue gases (initial concentration of NO 1000, 750, 400 ppm, : $N_2$ balance gas). Characteristics of NOx reduction are measured and analysed in corona discharge of multi needles to plane electrode structure and magnetic field. The best characteristics of NO reduction is measured when electric and magnetic field were supplied to reactor, at same time. Consumption power applied electric and magnetic field were higher than that of discharge applied only electric field.

The gas-insulated switchgear(GIS) has made high-reliability, high-safety, compact substations possible by using $SF_6$ gas. They are likely to be further developed toward higher voltages and targer capacities, along with greater compactness and lower cost. Although $SF_6$ gas has excellent insulation performance, breakdown voltages are reduced by the conducting particles. Thus, extensive studies have been made on the breakdown characteristics of $SF_6$ gas in particle contaminated conditions. Experiments were carried out for fired particle and free particle in a coaxial electrode system with DC and AC voltages. This paper represents the experimental results of the processes involved in electrical breakdown in compressed $SF_6$ gas, where breakdown is initiated by conducting particles.

This paper describes the effect of floating metallic object on do flashover characteristics in all gap producing unipolar ion flow field. Needle-to-plane electrodes of 120mm in gap length were used as the main gap electrode and the tested metallic objects were spheres with the radius of 2,10 and 15mm or needles from 5 to 40mm long. The characteristics of flashover voltage vs. location of the floating object are different completely with the shape of the floating metal and polarity of the applied voltage.

A Sputter ion Plating(SIP) system with a r.f. coil electrode and the Facing Target Sputter(FTS) source was designed for high-quality thin film formation. The rf discharge was combined with DC facing target sputtering in order to enhance ionization degree of a sputtered atoms. The energy of ions incident on the substrate depended on the health potential of DC biased substrate. The mean impact ion energy increased with negative bias voltage and rf power. The adhesive force of the TiN film formed was in the range of 30$\sim$50N, and markedly influenced by substrate bias voltage.

The variations of cold gas properties such as density, pressure, temperature and velocity which are dependent each other are closely related with the dielectric recovery of an interrupter. So, the pressure-rises at no-load in the puffer cylinder and in front of fixed arcing contact of 800kV model interrupter were measured experimentally using pressure transducers of strain gage type and semiconducting type, respectively. The maximum value of pressure-rise in the puffer cylinder increased almost linearly from 7.6 bar at the minimum operated pressure to 9.7 bar at the maximum operated pressure, while the pressure-rise in front of fixed arcing contact was independent with the operated pressure. The measured values will be utilized in verifying the self-developed cold flow analysis program and as an input of commercialized CFD program package.

This paper presents a method witch tan improve the dielectric recovery characteristics of UHV class gas circuit breakers by changing the nozzle shape. To calculate the dielectric recovery voltage between electrodes, the flow field and electric field analysis in a 362kV model interrupter has been performed with the commercial programs, RAMPANT and FLUX2D, respectively. As a result, we found that the nozzle shape affects the characteristics of dielectric recovery between electrodes and obtained great improvement of it by the changing the downstream nozzle shape.

In designing three phase enclosure type EHV class gas insulated bus (GIB), it is essential to estimate the magnitude and the position where the maximum electric field strength occur. The improvement of insulation design can only be initiated after those informations have been obtained. In this paper, the calculated electric field strength for three phase GIB of HICO 362kV 63kA GIS is presented. The result shows that the designed insulator has enough margin compared with the design criteria.

Broadband Microwave Low Noise Amplifier(LNA) is designed. The matching method using the broadband BPF(BandPass Filter) is introduced in this paper. This method is that the filter having the same reflection coefficient of Microwave GaAs FET in the desired bandwidth is located on the input stage of FET. The Simulated results is obtained that the $S_{21}$ and noise figure in 2.5GHz$\sim$9GHz, band are 8.5dB $\pm$ 1.5dB, 2.5dB $\pm$ 0.3dB respectively.

This paper has represented the new system for a multibit oversampled sigma-delta A/D convertor. The novel digital correction scheme with the ROM-Table is employed to enhance SNR without requiring accurate precision of the analogue components. This architectures have a good features compared with the 1-bit approach, including significantly lower quantization noise for a given oversampling ratio, as well as improved stability characteristics. Then we have shown the validity of the proposed system by use of the software for the performance evaluation and by realizing the system with SCFs(switched capacitor filter).

Recently, as power transformer capacity is getting larger, vibration noise of transformer would be large and unexpected failuare of transformer give enormous economic loses, So we aquaire vibration signal, which is maked from transformer windings, core that are airtight out box with in insulation oil, and out box. Also we are fixed rated voltage and changing load current, analyize frequency domain of each vibration signals.

A power line data transmission method has been developed and presented in this paper. Although there have been efforts to develope power line data transmission techniques, none of them has been accepted as a standard. Thus, our method follows a defacto standard CENELEC's recommendations. The paper presents the algorithm as well as experimental results.

In this paper, the generation of the intensive ultrasonic waves depend mainly on the energy convention efficiency depending on high frequency oscillation of the generator and the control performance of stable output depending on iode variation. As a result, the ultrasonic generator obtained of 95% differency with 28khz.

In video image compression, it is important to extract the exact notion information from image sequence in order to perform the data compression, the field rate conversion, and the motion compensated interpolation effectively. It is well known that the location of the smallest sum of absolute difference(SAD) does not always give the true motion vector(MV) since the MV obtained via full block search is often corrupted by noise. In this paper, we first classifies the input blocks into 3 categories : the background, the shade-motion, and the edge-motion. According to the characteristics of the classified blocks, multiple locations of relatively small SAD are searched with an adaptive search window by using the proposed method. The proposed method picks MVs among those candidates by using temporal correlation. Since temporal correlation reveals the noise level in a particular region of the video image sequence, we are able to reduce the search are very effectively.

Applications of the fiber optic sensing are glowing rapidly, particularly in situations where size, weight, speed, and immunity to electromagnetic interference are important considerations. The fiber optic current sensors have been developed for low frequency(60Hz) metering in electric power systems. But we try measure to high frequency large current by fiber optic current sensor based on Bi substituted rare earth iron garnet. In this paper, we report the linearity to 500 amperes and frequency response of signal processor and a result of detection the standard impulse large current of fiber optic impulse sensor system.

A fiber-optic pressure sensor is fabricated with a photoelastic glass material. To remove the influence of external pertubation along the optical fiber, a new referencing technique is proposed by using two light sources. LED with 870nm wavelength is used as light source for reference signal, and LED with 660nm wavelength is used as light source for modulation signal. The fiber-optic pressure sensor system shows good linearity within the pressure range of 0 to 5 $kg/cm^2$.

A computer aided process is inevitable for the optimization of train operation planning. Developing of train diagrams is very important for the train operation planning. In this paper, the user friendly program related to the train scheduling that can be used for the basic data on developing of train diagram is introduced. It can also provide basic data for other train operation plannings, such as Timetabling, Crew Operation Scheduling, etc. It provides the planner with data moving, data changing and zooming functions, and it can assist the user easily produces their optimal solution. All this operations are performed interactively through graphic windows.

This paper presents an integrated fault diagnosis expert system for power systems. The proposed system diagnoses various faults occurred in both substations and transmission lines even in the case that substation fault is spreaded over the network. To cope with this problem, A meta-inference method is proposed. This scheme shares same the data structure with the pre-developed intelligent operational aid expert system installed in a practical sub-control center, without modification. This advanced integrated diagnosis system is developed using a low cost personal computer owing to the special modular programming technique. Case studies show a promising possibility of the proposed method.

ATS Systems are activated against the over-running and the crashes between trains. Up to now, ATS Systems have been constituted analog systems adopting the changed frequency method or amplitude modulation, which is impossible to give any essential informations. In this paper, it is dealt with digital ATS Systems which are replaced the former ATS Systems in the advanced nation of railways. Especially, this paper shows the possibility of any developments for the digital ATS Systems by the experiment of digital ATS Systems by Frequency Shift Keying method.

This paper presents an improved algorithm of optimal measurement system design with a reliability evaluation method for a large power system. The proposed algorithm is developed to cosider the observability and to achieve highest accuracy of the state estimator as well with the limited investment cost. When the effect on these dummy bus measurements is considered in the proposed algorithm the other errors in the power system is also detected and then analyzed until to achieve the limited values. By taking advantage of the matrix sparsity and the optimal bus ordering the memory and the time are successfully reduced in the P/C's and workstation's model. The improved program is successfully tested for IEEK sample system and KEPCO system with PSS/E lineflow calculated data package.

In this paper, traffic modeling and control design was considered to analyze and improve the stability of train diagram in the open-loop Metro line. A complete discrete-event traffic model describing the natural instability of open-loop metro line is analyzed. The traffic stability properties are introduced and easy-to-implement state feed back traffic control algorithms are designed, which satisfied with system stability.

This paper describes the effect of the train ticket allocation methods. Two types of the allocation method, 'proportional to the distance between two stations' and proportional to ticket-demand', are compared. From the result of calculation, the letter case shows better characteristics than the former case especially on the scat occupation ratio and the regional equality or allocation.

In this paper, a realization of a real-time train information system(TIS) is discussed. The requirements of TIS which satisfy real-time constraints are analyzed in view of data transfer. For efficient data communication in TIS, a new network system is suggested and its real-time characteristics are analyzed and compared with the standard network system. A local unit is designed based on VMEbus system.

We propose the improved threshold current ratio method to determine the reflectivity of coated facets. The carrier recombination time used in the improved threshold current ratio method depends on the value of facet reflectivities. However, the carrier recombination time used in the conventional threshold current ratio method is constant regardless of facet reflectivities. The difference between the results of the two methods increases as the reflectivity of a coated facet decreases.

Tunneling of an electron non-normally incident on a potential barrier is theoretically studied. Tunneling time and the position where an electron appears after the tunneling are derived using the phase time approach. The positions where photons appear after two-dimensional tunneling in a frustrated total internal reflection structure are also discussed.

We analyze the nonlinearity of chiral media and coupled-mode theory of chiral multilayers. In first topic, second order nonlinear coupled equations are constructed and a phase matchine method is suggested. This approach can be developed to higher order nonlinearity and electric-field-induced second harmonic generation. In second topic, coupled mode equation in chiral multilayers is constructed, and solved for both codirectional coupling and contradirectional coupling. There is a previous formulation about chiral mutilayers[1] with 4$\times$4 matrix but it did not give detail results, so this approach will be compared with that.

In long-haul high speed optical communications, the distance between a transmitter and a receiver depends on the amount of light coupled to a single mode optical fiber from the laser diode(LD) as well as the LD characteristic itself. And the transmitter module must have long lifetime. high reliability, and even simple structure. Such points have induced laser welding technique to be a first choice in opto-electronic module packaging because it can provide strong weld joint in a short time with very small coupling loss. In this paper, packaging considerations and characteristics for high speed LD modules are discussed. They include optical path design factors for larger aligning tolerance, and novel laser welding processes for component assembly. For low coupling loss after laser welding processes, the optical path for optimum coupling of a single mode optical fiber into the LD chip was designed with the GRIN lens system providing sufficiently large aligning tolerance both in the radial and axial directions. The measured sensitivity of the LD module was better than -33.7dBm(back to back) at a BER of $10^{-10}$ with a 2.5Gbps NRZ $2^{23}-1$ PRBS.

In near field optics, optical fiber probe is smaller than the wavelength of light. This small probe makes it possible to overcome the diffraction limit due to wave property of light. In conventional optical systems, the image resolution is governed by wavelength. But in NSOM, it is determined by probe tip size and probe shape. Therefore probe tip size and shape are very important points in near field optics. In this paper, we will suggest the new fabrication methods of optical fiber probe and show that the probe tip size is sub-micrometer using SEM.

Tunneling current from filed emission display tips is calculated by numerical analysis using a finite element method software. For simple tip structures it is shown that the image charge method could provide an efficient way to estimate the tunneling current.

기존의 가상현실(Virtual Reality) 시스템들은 가상세계 (Virtual World)에 관한 데이타를 대부분 파일의 형태로 관리하고 있다. 가상현실에 대한 연구가 진전되어 공유가상세계(Shared Virtual World)를 기반으로 하는 대규모 응용분야가 나타나면서, 데이타의 효율적 관리와 공유를 위한 상위 레벨의 데이타 관리층이 필요하게 되었다. 본 논문에서는 가상세계 데이타의 관리를 위한 객체지향 DBMS(Database Management System)[1]의 사용을 제안한다. 그리고 데이터베이스에 저장된 지속객체 (Persistent Object)[2]를 공유하는 가상현실 응용시 스템의 구조를 연구한다.

An optimal routing method using hysteresis binary neurons with link failure probability is proposed in this paper. The link failures in computer networks can degrade the performance of the entire networks. We assume the time between successive link failures is exponentially distributed with parameter ${\lambda}$ and the failures are independent. The link failure probability is used for neural networks to find the shortest paths of given source-destination pairs. By using the probability of link failures and hysteresis binary neurons we implement an optimal routing method that can takes routes by coping with link failures.

This paper compares the simulated annealing and the Hopfield neural network method for an optimal routing in a multistage interconnection network(MIN). The MIN provides a multiple number of paths for ATM cells to avoid cell conflict. Exhaustive search always finds the optimal path, but with heavy computation. Although greedy method sets up a path quickly, the path found need not be optimal. The simulated annealing can find an sub optimal path in time comparable with the greedy method.

In general, the control of robot manipulator is classified into position control and force control. Position controllers give adequate performance when a manipulator is following a trajectory through space and end-effector has no contact with environment. However for most tasks performed by robot manipulator in industry, contact is made between the end-effector and manipulator's environment, so position control may not suffice. The objective of this study is to control both position of a manipulator and the contact forces generated at the hand by using a conceptually simple control law. Position and force control problem is decoupled into subtasts via taskspace formulation and inverse dynamics. Then, the position controllers are designed for the task space variable which represent tangent motion and the forte controllers are designed for the lash space variables which represent normal force.

Recently, the vision system has the wide and growing' application field on account of the vast information from that visual mechanism. Especially, in the control field, the vision system has been applied to the industrial robot. In this paper, the object tracking and grasping task is accomplished by the robot vision system with a camera in the robot hand. The camera setting method is proposed to implement that task in a simple way. In spite of the calibration error, the stable grasping task is achieved using the tracking control algorithm based on the vision feature.

In this paper, a nor fuzzy control algorithm for the target tracking system is proposed, and its characteristics are analyzed and compared with those of the traditional PID controller. Fuzzy rules are generated experimentally using Mamdani's minimum operation and the center of area method. The experimental results prove that the proposed fuzzy algorithm is excellent in our tracking system and its performance is superior to that of the PID controller.

The safe navigation of a mobile robot requires the recognition of the environment in terms of vision processing. To be guided in the given path, the robot should acquire the information about where the wall and corridor are located. Also unexpected obstacles should be detected as rapid as possible for the safe obstacle avoidance. In the paper, we assume that the mobile robot should be navigated in the flat surface. In terms of this assumption we simplify the correspondence problem by the free navigation surface and matching features in that coordinate system. Basically, the vision processing system adopts line segment of edge as the feature. The extracted line segments of edge out of both image are matched in the free nevigation surface. According to the matching result, each line segment is labeled by the attributes regarding obstacle and free surface and the 3D shape of obstacle is interpreted. This proposed vision processing method is verified in terms of various simulations and experimentation using real images.

X-Ray Diffraction method that gives direct information about the deformation of crystal lattice is used for the determination of profiles of the residual stress along the depth of heavily boron doped silicon. The residual stress distribution is obtained by XRD method as measuring the deformation of the front surface of the $p^+$ silicon layer fabricated through different etch time. It is determined that the compressive residual stress exists in the most region except the font surface.

We have analyzed the dielectrophoretic(DEP) force on a cell in a micro planar electrode structure. We fabricate a micro planar electrode structure using micro machining technology and measure the motion of a cell that is accelerated by DEP force. DEP force on a cell is calculated by curve fitting the motion of a cell. Radish and yeast are used for the experiment. In case of radish, DEP force is increased as the voltage and the frequency is increased, and in case of yeast, DEP force is increased only as the voltage is increased DEP force on a yeast does not vary when the frequency varies from 1 MHz to 3 MHz. The result will be helpful to the manipulation of cells using DEP force.

Using the $O_2$ RIE process, 20{\mu}m$-height polyimide microstructures are fabricated. In LIGA-like process, metal microstructure can be formed by the electroplating using these polyimide microstructures as a plating mould. Reactive ion Etching technique using oxygen gas is used for the patterning of polyimide. The etching rate of the polyimide is increased with increased pressure and RF power. The anisotropic vertical sidewall can be obtained at low pressure, but the etched surface state is not so good yet. "Micrograss", which is formed during the RIE and disturbs uniform electroplating, can be removed effectively by the wet itching of the chromium sacrificial layer. More studies about the improvement of an etched surface state and the removal of microsgrass are needed.

We present a novel method. to fabricate surface micromachined structures without their sticking on the substrate. An anhydrous HF/$CH_3OH$ vapor-phase etching (VPE) of sacrificial $SiO_2$ layers was employed to release 0.5-2 {\mu}m$ thick polysilicon cantilevers. The fabricated structures were observed using scanning electron microscope and 3-dimensional optical microscope. The results show that we can successfully make cantilever beams up to 1200{\mu}m$ long without sticking. Annealing effects on residual stress of polysilicon microstructures were also investigated. Anneal ins at 1100$^{\circ}C$ for 1 hour was found to be effective to release the residual stress of the polysilicon microstructures. These VPE and anneal ins techniques will be useful in surface micromachining technologies.

A thermally actuated micro-relay using a mercury-contact has been designed and fabricated. The mercury actuation was achieved by external nitrogen pressure and the mercury-contact was moved by actuation pressure of 110torr in the 100${\mu}m$ wide microchannel. The Injection pressure of mercury was 300torr in the 60${\mu}m$ wide microchannel of the micro relay structure.

In this study, we experimented the properties of SOG film as sacrificials layers in surface micromachining and made $SiO_2$ films through spin, bake, cure process. When we culled SOG films once, SOG film thickness is 1000 $\sim$ 3000 ${\AA}$. Then we coaled 200-${\AA}$ SOG film on 9000 ${\AA}$-CVD oxide and then we fabricated test structure, cantilever and ring/beam structure. We estimated deformed structure by SEM. As the results, The deformation of the structure layer in the SOG-coated sacrificial layers is small compared with that or the structure layer on CVD oxide or PSG. In the future, we use multi coated SOG films, SOG film become adequate material as sacrificial layer.