• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1442_1442
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• 2009

This paper describes electric field analysis and design of direct current arresters for electric traction vehicles. Generally, DC arresters are used to protect the electric traction to limit the overvoltage invading into its inner electrical circuits. We could proposed operating voltage(Uc), the rated voltage(Ur). Finally maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the DC arresters.

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.84-88
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• 2008

In this paper, we analyze the errors associated with electric field interference for fiber-optic voltage sensors working in a three-phase electric system. For many practical conductor arrangements, the electric filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of 1 %.

• 전기저널
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• 3호통권75호
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• pp.25-27
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• 1983

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권3호
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• pp.149-156
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• 2004

This paper deals with the effective protection method for the household electric appliances against lightning surges invading from the Power lines. Direct or induced lightning is the main cause of the breakdown of household electric appliance. The most effective protection method is to install SPDs(surge protective devices) at household electric appliances. If SPDs were not installed at most household electric appliances, it is necessary to install SPDs on the mains. Therefore the propagation aspect and protection methods of lighting surges coming into household electric appliances through the mains was experimentally investigated. The in actual-sized test circuits results of protection method for 8 household electric appliances including computer monitors and TV set could be summarized as follows: The breakdown characteristics of household electric appliances from lightning surges were significantly changed with the their input impedance. Namely, the types of input impedance are classified into infinite, resistive or inductive impedances. Especially, the monitor for computer with inductive input impedance from lightning surges was relatively weak against lightning surges. It was confirmed that the self inductance of branch circuits on the mains have protection effect for household electric appliances against lightning surges invading from the power lines. Also the varistors installed at cabinet panel or circuit-breaker were more effective than multi-tap outlet with varistors. When installed varistors in cabinet panel and multi-tap outlet together, the surge protection effect is much more excellent in technical and economical aspects.

• Journal of Power Electronics
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• 제18권4호
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• pp.1255-1267
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• 2018

Parasitic parameters have a larger influence on Silicon Carbide (SiC) devices with an increase of the switching frequency. This limits full utilization of the performance advantages of the low switching losses in high frequency applications. By combining a theoretical analysis with a experimental parametric study, a mathematic model considering the parasitic inductance and parasitic capacitance is developed for the basic switching circuit of a SiC MOSFET. The main factors affecting the switching characteristics are explored. Moreover, a fast-switching double pulse test platform is built to measure the individual influences of each parasitic parameters on the switching characteristics. In addition, guidelines are revealed through experimental results. Due to the limits of the practical layout in the high-speed switching circuits of SiC devices, the matching relations are developed and an optimized layout design method for the parasitic inductance is proposed under a constant length of the switching loop. The design criteria are concluded based on the impact of the parasitic parameters. This provides guidelines for layout design considerations of SiC-based high-speed switching circuits.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.264-266
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• 2005

Recently, on-line diagnosis methods through wired and wireless networks are widely adopted in the diagnosis of industrial Electric Facilities, such as generators, transformers and motors. Also smart sensors which includes sensors, signal conditioning circuits and micro-controller in one board are widely studied in the field of condition monitoring. This paper suggests an self-powered system suitable for condition-monitoring smart sensors, which uses parasitic vibrations of the facilities as energy source. First, vibration-driven noise patterns of the electric facilities are presented. And then, an electromagnetic generator which uses mechanical mass-spring vibration resonance are suggested and designed. Finally energy consumption of the presented smart sensor, which consists of MEMS vibration sensors, signal conditioning circuits, a low-power consumption micro-controller, and a ZIGBEE wireless tranceiver, are presented. The usefulness and limits of the presented electromagnetic generators in the field of electric facility monitoring are also suggested.

• Journal of the Optical Society of Korea
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• 제11권4호
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• pp.177-182
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• 2007

This paper discusses the errors associated with electric field cross talk for optical voltage sensors in a three-phase electric system and provides a solution to compensate the errors. For many practical conductor configurations, the electric field cross talk may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the cross talk and built an electronic circuits based on it. The mechanism of the compensation and the corresponding error reduction were discussed.

• 한국광학회지
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• 제10권3호
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• pp.259-264
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• 1999

CRT 디스플레이 시스템의 입력 신호와 방출되는 빛의 세기 관계를 유도하였다. 빛의 세기는 입력 신호뿐만 아니라 비디오 보드, 전자회로부, 그리고 CRT 특성에도 의존한다. 특히 전자회로부의 증폭률과 옵셋 전압에 따라 휘도 곡선이 크게 달라진다. 본 연구에서는 디스플레이의 contrast 누름 단추와 brightness 누름 단추를 사용하여 전자총의 독립성이 최대로 유지되는 최적상태로 시스템을 설정하였다. 최적상태에서의 디스플레이 시스템의 시간 안정성과 화면 균일도, 그리고 색 선명도를 평가하고, 실제 사용환경을 고려하여 암실과 명실에서의 명암대비를 비교하였다.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.44-51
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• 2012

The purpose of this study is development of the diagnosis system to preventative maintenance in the on-board measuring systems for in-cab electric inspection systems of high speed railway. The on-board measuring systems can inspect precisely whether ground signal system operate stably. In this paper, we recognize characteristics of the track circuits and confirm whether the wave of current matches the on-board measuring data through the electric modeling method for high speed railway. it is necessary to develop GUI visual programs that can simulate abnormalities of the on-board measuring data in many ways, and the visual program is designed to diagnosis in the case of track circuit equipment's function decreased in advance.

• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.952-957
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• 2003

We propose how to translate relay circuits to the EMFGs(Extended Mark Flow Graphs) formally and analyze the original one by using the mark flow of it. Firstly, the concepts of the output condition, the output-on condition and the output-off condition are introduced in the relay circuits. These can be used to find the structure and the operation of respective relay outputs but the sequential operations of them cannot be obtained from these. Secondly, a relay circuit is translated to the corresponding EMFG as the all output-on conditions and all output-off conditions of it are translated to EMFGs. For the adequate translation, the condition arc and the concepts of the generation transition and the degeneration transition are introduced, and the duality for the simplification of the result. Thirdly, we analyze the operation of the original circuit by analyzing the mark flow of the resulting EMFG. We can achieve easy and fast analysis based on the EMFG's operation algorithm. Finally, we apply these to the relay circuit for an electric furnace and analyze its operation with the mark flow of the resulting EMFG. The formal translation from relay circuits to EMFGs makes the analysis easy so that these results can be used to design, modelling, the fault detection and the maintenance.