• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1314-1316
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• 1995

Basic discharge characteristics of a ferroelectric ball and mica sheet double barrier have been studied for learning the fundamentals of the barrier discharges and for checking the potential to be used as a plasma generator. It is found that plasma generation of the plasma generator was influenced greatly by the dielectric constant of the ferroelectric ball barrier and applied power frequency. As a result, there are optimum conditions of the dielectric constant as a barrier and the applied frequency to generate ozone effectively, which were ${\varepsilon}_r$=600 and f=4 kHz at the present experimental case.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.6
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• pp.803-812
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• 1998

In this study, testing equipment with which several kinds of valves can be tested was composed. Two kinds of tilting check valves and a swing check valve were tested to analyze their dynamic characteristics. The results of the experiment showed that the tilting check valves protected the pump but that the swing check valve could not protect the pump when the reverse flow rate was high. Also the dynamic equation of the tilting check valve was formulated and simulated using system characteristic constant t$_{c}$ and one method of predicting t$_{c}$ by comparing the results of the simulation with the results of the experiment was proposed.sed.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.45-48
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• 1990

This paper deals with the control strategy for constant voltage, constant frequency (CVCF) generation of doubly-fed Induction generator. As induction machine is a nonlinear and multivariable machine, so, the influential factors for CVCF generation of induction generator are the magnitude of output voltage, load current and its power factor, slip of the machine, etc. To get appropriate control scheme and to research the effect of its parameters, the control equation of induction machine is derived and tested. The derived condition is very useful for the CVCF control of the machine and for determing the characteristics of the system. The simulation results show that magnetizing reactance and rotor resistance is a very important parameter in this control system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.10
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• pp.505-509
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• 2004

The (Sr/sub 0.9/Ca/sub 0.1/)TiO₃(SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/SiO₂/Si) using RF sputtering method at various substrate temperature. The optimum conditions of RF power and Ar/O₂ ratio were 140[W] and 80/20, respectively. Deposition rate of SCT thin film was about 18.75[Å/min]. The crystallinity of SCT thin films were increased with increase of substrate temperature in the temperature range of 100～500[℃]. The dielectric constant of SCT thin films were increased with the increase of substrate temperature, and changed almost linearly in temperature ranges of -80～+90[℃]. The current-voltage characteristics of SCT thin films showed the increasing leakage current as the substrate temperature increases.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.791-794
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• 1998

This paper presents a constant gm input stagefor low-voltage rail-to-rail operational amplifier. A proposed scheme uses two current paths to keep sum of the biasing currents of the complimentary input pairs. The op amp was designed in a $0.8\mu\textrm{m},$ n-well CMOS, double-polysilicon and double-metal technology. This achieved in weak inversion. The circuit can operate in power supply voltage from 1.5V up to 3V. An open-loop gain, AV, was simulated as 84dB for 15pF load. An unit-gain frequency, fT was 10MHz.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.262-270
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• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2110-2112
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• 1997

The induction motor drive for the spindle of machining center is required to do not only a constant torque operation in low speed region(below base rpm), but also a constant power operation in high speed region(beyond base rpm). Also, control voltage shortage due to high speed operation must be overcome. The vector controlled inverter system with input 3 phase pwm converter is designed for that kind of condition. We experimented the performance of the inverter system with spindle motor made by Hyosung industries co.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.414-417
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• 2001

SRG (Switched Reluctance Generator) have many advantages such as high efficiency, low cost, high-speed capability and robustness compared with characteristics of other machines. However, the control methods that have been adopted for SRGs are complicated. This paper proposes a simple control method using PID controller that only controls turn-off angles while keeping turn-on angles of SRG constant. The linear characteristics between the generated current and the turn-off angle can be used to control the turn-off angle for load variations. Since the reference current for generation can be produced from an error between the reference and the real voltage, it can be controlled to keep the output voltage constant. The proposed control method enhances the robustness of this system and simplifies the hardware and software by using only the voltage and speed sensors. The proposed method is verified by experimental results.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.1017-1025
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• 2004

Generally generator is connected to the bus with no load. After the connection to the bus. the frequency of generator system with no load has to be increased for preventing the reverse power. But in a few case of parallel running with infinite bus system, we have to synchronize the loaded generator to the infinite bus. The frequency of generator system with load has to be lowered for prevention of load shift to the bus system. The blackout of infinite bus decreases the parallel running generator's frequency because of load increasing. In this paper we propose a method that the generator with load maintains the frequency constantly after the blackout of infinite bus. With the constant speed control and load control method of parallel running system to the infinite bus we apply the method to the industrial generating system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.241-246
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• 2004

This paper proposed trajectory tracking control of mobile robot. Trajectory tracking control scheme are real coding genetic-algorithm and back-propergation algorithm. Control scheme ability experience proposed simulation. Stable tracking control problem of mobile robots have been studied in recent years. These studios have guaranteed stability of controller, but the performance of transient state has not been guaranteed. In some situations, constant gain controller shows overshoots and oscillations. So we introduce better control scheme using Real coding Genetic Algorithm(RCGA) and neural network. Using RCGA, we can find proper gains in several situations and these gains are generalized by neural network. The generalization power of neural network will give proper gain in untrained situation. Performance of proposed controller will verify numerical simulations and the results show better performance than constant gain controller.