Nowadays as the power systems have been more complicated and have grown to ultra high voltage, it requires a accurate and high speed relaying scheme to improve the reliability and stability of power systems for a harmonious power supplying. For this purpose voltage and current have to be measured at the location of the protective device and the short circuit impedance must be determined. This paper presents the application methods and some results of digital distance relaying scheme which is based upon the theouy of real-time symmetrical components. Usually the symmetrical component have been used to solve the transient systems as well as the steady state systems under unbalanced systems. But, real-time symmetrical component frequently have not been applied to on-line control region of the large power system. We have tried to apply this method to deal with the various type of faults on artificial transmission line. And experimental results demonstrate the validity of the proposed techniques. Therefore, this study is expected that it is contributed to improve the reliability of power supplying, searching for the fault location rapidly and exactly in power system.

A position detection method for 2 phase bifilar permanent magnet step motors is proposed. The back emfgenerated on 2 phase windings by rotor permanent magnet is calculated using motor terminal voltage and current by analog circuit, and the rotor position output is obtained from tese back emf signals through some logical manipulation circuit. This position detector functionally acts like a 2 channel optical incremental encoder, and it is also shown by experimental results that it works well over wide range of speed or under resonant condition where the rotor rings around the detent position. Its resolution is twice of the number of steps per revolution. Bu software implemented on micro-processor, the reliability of position output is enhanced, detecting and correcting error dut to external and/ or internal noise.

A new method for the modeling of non-ideal dc-dc converters whose switching times are finite is proposed. The effects of finite turn-on, turn-off times, delay time, storage time, reverse recovery process on the system stability, dc transfer function and efficiency are investigated. It is verified how system poles are changed and how dc transfer function and efficiency are decreased by non-ideal switching.

This paper shows the design method and the experimental results of the thin film thickeness monitor. The thin film thickness monitor uses 6 MHz quartz crystal in sensor and cooling system for the fine operation. The thin film thickness are measured by the digital frequrency counter.

The high-power Nd:glass system with five-stage amplifier was designed and its amplification characteristics was studied for developing high-power Nd:glass laser system as an energy driver of inertial confinement fusion(ICF). In order to study the amplification characteristics of remporal and spacial Gaussian laser beam, the dependence of them on pumping efficiency and rod loss were studied and discussed. The output energy of this system using phosphate Nd glass rod(LHG-7,LHG-8) and silicate Nd glass rod(LSG-91H), respectively, was calculated by the computer simulation using Avizonis-Grotbeck and Frantz Nodvik equations. As results of this simulation, it was found that the shorter the risetime of laser pulse, the larger the amplification factor and that the larger peak value of laser pulse, the lower the amplification factor. The output inergies of 179J, 344J, and 7J were obtained by the designed five-stage amplified high-power Nd:glass laser system using glass rods of LHG-7,LHG-8, and LSG-91H, respectively. From the results it was found that the laser system using the LHG-8 glass rod was the most excellent one among the systems and the cross section for stimulated emission of the gain coefficient was essentially important parameter for the amplification characteristics.

A robustness analysis for model reference adaptive control(MRAC) system with plant uncertainty is discussed in this paper. The adaptive control system is designed under assumptions that the controlled plant is represented by a lst order nominal model and that the system is drived by a constant reference signal. When using general gradient method(GGM), it is shown that unmodelled dynamics in plant model can cause the instability of the overall control loop during the adaptation process. However, as the algorithm of least square method(LSM) is introduced, the global stability of the system can be hold. And it is also given that the boundedness of adjustable parameters may be verified using the concept of an equilibrium point analysis.