• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2083-2085
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• 2000

우리나라의 전열추진기술 프로그램에 따라 8�V의$\square$ $\square kJ$ 커패시터 뱅크 모듈이 제작되고 있다. 한 �V의 모듈은 6개의 22kV, 50kJ 자체 고장복구 커패시터와 주 스위치로서 각 모듈에 하나씩의 RVU-43 스위치를 사용하였다. 또 각 모듈에는 요구되는 전류 파형의 폭을 얻기 위하여 $20\sim160\;\mu\;H$의 펄스 파워 인덕터를 사용하였고 3개의 병렬 크로우바 스택을 적용하였다. 여러 종류의 스위치가 검토되었으며 그 중에서 펄스 파워 싸이리스터보다 가격이 싸면서 전류영점에서 차단기능이 있는 RVU-43 스위치가 선정되었다. 선정된 스위치(정격 25kV, 200kA, 120 Coulomb)에 대하여 자기방전 전압, 최소 동작전압, 동작 지연시간, 역전류 차단성능, 스위치 손실에 관한 특성시험을 행하고 그 결과를 보고한다.

• Progress in Medical Physics
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• v.15 no.2
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• pp.105-111
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• 2004

The parallel plate detector with dielectric film for dosimetry was designed to measure detection characteristic of 6 MV X-ray with medical linear accelerator. PTFE film was inserted into FEP films that are made by two one-side metal coated materials for ion source. The thicknesses of PTFE dielectric film was 100 ${\mu}{\textrm}{m}$ and the thickness of FEP dielectric film was 100 ${\mu}{\textrm}{m}$, respectively. This detector was fixed by two acrylic plate for physical hardness ad geometrical consistency. The geometrical condition for measurement with parallel-plate for detector was below; SSD=100 cm and the 5 cm depth between detector and phantom surface The major parameter of detector characteristics such as zero drift current, leakage current, charge response by applied voltage, reproducibility, linearity, TMR measurement, dose rate effect were measured. The zero drift currents are 8.3 pA and leakage currents are 10 pA. The charge response of applied voltage is showing linearity in 414 voltage. The measurement deviation of reproducibility in this detector is within 1% for dose and the linearity of applied dose shows in this detector. The TMR curves in phantom between this parallel plate detector and reference detector are matched within 3% deviation from maximum dose depth to 7.5 cm depth. It is considered that this dosimetric system is satisfactory for the purpose of the constancy check of the 6 MV x-ray from medical linear accelerator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.62-68
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• 2006

In this paper, an adaptive input-output linearization and zero dynamics control of three phase AC/DC converter are proposed. For achieving output do voltage regulation with unity power factor, the q-axis current of the rotating d-q frame is regulated to zero and the output do voltage is controlled to track a given reference voltage $V_r$. The proposed scheme is robust to the parametric uncertainty md load current of the converter due to the adaptation process. The simulation results are presented to illustrate the performance and feasibility of the proposed control scheme.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1772-1774
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• 2004

Because the physics occurring during an interruption process is not well known, it is not easy to analyze the characteristics of a self-blast circuit breaker neither theoretically nor experimentally. Fortunately the available computational power and the numerical method improved recently make it possible to predict an interruption process as precisely and fast as possible. Therefore many researches using computational methods have been done for the interruption process of interrupters and applied to extend the information such as thermal and dielectric reignition. In this paper, we have simulated the interruption process of SF6 self-blast circuit breakers with the arc plasma during the fault interruption of a 10 kA current. The CFD program used here is coupled with the electromagnetic field analysis, the radiation model and the effects of turbulence. Through this work, we have get further information about the thermal performance as well as the behavior of the arc. The results have been compared with the measured arc voltage.

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.5
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• pp.1-9
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• 1971

An analog to digital converter Ivhich is applicable to mass production of digital multimeter is developed. The solid state digital instrument has accuracy $\pm$0.1% of feading $\pm$1 digit over 1 mV to 1000 volts with high input impedance and automatic function. All possibility to affect the distortion of A/D converter is tudied. As a result, useful linearity with high temperature stability of integrating waveforms is achieved by the very simplified circuit configuration to assure the proposed accuracy under various ambient condition.

• Proceedings of the KIEE Conference
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• summer
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• pp.1100-1102
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• 2004

열팽창 방식의 가스차단기는 아크 에너지 자체를 이용하여 압력상승을 얻고, 상승된 압력을 이용하여 전류 영점 부근에서 아크 방향으로의 유동을 형성하여 아크를 소호한다. 대전류 구간에서 노즐 폐색현상이 일어나면 노즐 용삭이 크게 일어나며 용삭된 노즐 물질은 팽창실의 압력과 온도를 상승시키게 된다. 따라서 차단 특성해석을 위해서는 노즐 용삭에 의한 압력 상승해석이 필요하다. 본 논문에서는 아크에너지에 따른 노즐 용삭비를 이용하여 용삭되는 노즐량을 계산하고, 이로 인한 back flow현상을 고려한 해석 방법을 제안한다. 개발된 프로그램을 제작한 차단부 모델에 적용한 결과, 열팽창실의 압력상승치는 시험결과와 잘 일치함을 확인하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.69-74
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• 2021

This paper introduces a low-power voltage-controlled oscillator(VCO) with filters that consist of resistors and capacitors. The proposed VCO contains a 5-stage current mode buffer, and each buffer cell has a resistor-capacitor filter that connects input and output terminals. The filter adds a zero to the buffer cell. Because the zero moves the oscillation condition to high frequencies, the proposed VCO can generate a high frequency clock with low power consumption. The proposed circuit has been designed with 0.18 ㎛ CMOS process. The power consumption is 9.83 mW at 2.7 GHz. The proposed VCO shows 3.64 pJ/Hz in our simulation study, whereas the conventional circuit shows 4.79 pJ/Hz, indicating that our VCO achieves 24% reduction in power consumption.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.2
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• pp.113-118
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• 2007

In this paper, a novel approach to using Subcircuit of Pspice in designing feedback for DC-DC converter systems is proposed. Proposed new approach, the feedback design procedures which are based on small signal modeling are programmed as a subcircuit in Pspice. For this purpose, Analog Behavioral Modeling (ABM) is used. By using the subcircuit, the component values of the error compensation amplifier can be easily obtained by means of Pspice DC analysis. The methodology of development is presented in detail and application examples demonstrated the effectiveness of the proposed approach in designing feedbacks for DC-DC converters. The converter with PWM method used continuous current mode and calculated buck converter control signal with average and linear current technique. To decide pole and zero K-method was adapted and this kind of design procedure took stable function.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.9
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• pp.522-529
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• 2002

In this paper, computer simulations of the physical Phenomena occurring in the arc region before and after current zero were carried out to evaluate the thermal recovery characteristics of a Laval nozzle. A commercial CFD program "PHOENICS" is used for the simulation and the user-coded subroutines to consider the arcing phenomena were added to this program by the authors. The computed results were verified by the comparison with the test results presented by the research group of GE Co.(General Electric Company). In order to investigate the state of the arc region after current zero, the simulation was carried out with three steps. They are steady state arc simulation, transient arc simulation before current zero, and transient hot-gas flow simulation after current zero. The semi-experimental arc radiation model is adapted to consider the radiation energy transport and Prandtl's mixing length model is employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The post-arc current was calculated to evaluate the thermal recovery characteristics after current zero. Compared with the results obtained by GE Co., it has been found that the critical RRRV(ratio of rise of recovery voltage) will be determined previously by this study.his study.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1069-1074
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• 2020

Since DC has no zero point, an arc occurs when the DC circuit breaker performs a shutdown operation. In this case, a fatal accident may occur in the circuit breaker or in the grid, depending on the magnitude of the arc. Therefore, the shutdown performance and the reliability of the circuit breaker are important in the commercialization of HVDC. In this study, a superconducting LC circuit breaker was proposed to improve the performance and the reliability of the DC circuit breaker. The superconducting LC circuit breaker applied a superconducting coil to the inductor of the existing LC circuit breaker. Other than limiting the initial fault current, it also creates a stable zero point in the event of a fault current. To verify this, simulation was performed through EMTDC/PSCAD. Furthermore, the superconducting LC circuit breaker was compared with the LC circuit breaker with a normal coil. As a result, it was found that the LC circuit breaker with the superconducting coil limited the initial fault current further by approximately 12 kA compared to the LC circuit breaker with a normal coil. This reduced the arc extinguish time by approximately 0.16 sec, thereby decreasing the elctrical power burden on the circuit breaker.