• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.722-723
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• 2011

국가차원의 신재생에너지 활성화 방안에 따라 지자체 등의 분산전원 시설계획이 점차 증가하고 있다. 이에 따라서 기존의 radial 구조가 아닌 closed loop을 운영하기 위해서는 보호협조에 대한 문제가 확실히 해결되지 않고서는 계통을 안정적으로 운영할 수 없다. 따라서 본 논문에서는 radial 계통 및 계통이 변경되거나 분산전원이 연계 시 closed loop 구조를 가지는 계통의 보호기기 및 자동화 개폐기들을 Agent화 시켜 통신을 이용한 보호 및 고장 구간 분리 알고리즘을 제안 하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.303-305
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• 2003

This paper discusses single-phase AC-DC converter that driven by binary combination at different transformer winding ratio. It has a advantage that constructs a control system simply and obtain load current of good quality without filter circuit and free from noise or isolation for lower switching frequency. Also, this has merit that can do high power capacity. In this research, study on feedback circuit that consist for load stability of AC-DC multi-level converter.

• 전력전자학회논문지
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• 제23권4호
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• pp.281-285
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• 2018

An isolated feedback method for measuring the inverter DC-link voltage is proposed. This method provides a simple and economical solution to inverter control systems that use a flyback converter as a controller power supply. In the proposed method, data on the DC-link voltage are acquired when the primary side voltage appears on the secondary side of the flyback transformer, thereby eliminating the need to adopt an extra signal isolation method. To solve the non-synchronization problem between the flyback converter switching and main controller sampling, the external interrupt function of the micro-controller is used as a trigger signal for the A/D conversion.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.806-808
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• 1992

This paper describes a buried-island SOI MOSFET structure which can reduce the edge channel effect by improving the interface properties at the side wall of active island and by reducing the strength of electric field applied at the upper corner of the side wall from the gate. Also, the buried-island SOl structure can obtain the uniform thickness of SOl film. The buried-island structure can be achieved by Zone- Melting-Recrystallization of polysilicon and polishing. Both simulated and experimental results show that the buried-island SOl NMOSFET has less edge channel effect than the conventional SOl NMOSFET using LOCOS or mesa isolation technique.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1031_1032
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• 2009

The voltages of unit cells of a fuel cell stack are one of the most significant factors to detect failure conditions and thereof safely control and operate the fuel cell system. In this paper, we describe two methods to monitor the voltages of the unit cells of a stack in consideration of data accuracy, circuit extensibility to various numbers of cells, and cost. The reported methods are approached by (i) the power isolation of cell voltage monitoring part from the communications part and (ii) the utilization of a commercially available cell monitoring integrated circuit IC of a Li-ion battery.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.42_43
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• 2009

Ferroresonance is a resonance condition between a nonlinear iron core of a potential transformer (PT) and a capacitance. It can lead to PT voltages several times the normal equipment ratings, and cause the isolation broken and damage to equipments near the PT. This paper proposes a analysis method of PT ferroresonance in the time domain. Based on the simplified equivalent circuit, a differential equation was found and the flux was calculated when ferroresonance generates. The forced response and natural response were also analyzed. The performance of proposed analysis method was verified with the EMTP-RV generated data. The method can help analysis chaotic ferroresonance and periodic ferroresonance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2041_2042
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• 2009

The diagnostic/prognostic problems for condition based maintenance or Prognostics and Health Management has been used. Primary objectives of diagnosis/prognosis are maximizing system availability and minimizing downtime from fault isolation through more effective troubleshooting efforts. Diagnosis aims to detect the onset of failures to improve system performance and reduce life cycle cost by reducing the failure time. The prognosis can reduce operational and support total ownership cost and improve safety of machinery and complex systems. In this Paper, a fault diagnosis methodology has been described using a monopropellant propulsion system model as a test bench.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.218-222
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• 2007

This paper present the Three-Level converter for high power application. In converter system, magnetic components are important devices used for energy storage, energy transfer, galvanic isolation and filtering. The proposed Three-Level converter is to reduce the number of magnetic components. The secondary rectification was discussed by a single core transformer winding. The result of the analysis are verified using 1kW prototype.

• Journal of Power Electronics
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• 제14권6호
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• pp.1272-1280
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• 2014

This paper presents solutions for fault detection and diagnosis of two-level, three phase voltage-source inverter (VSI) topologies with IGBT devices. The proposed solutions combine redundant standby VSI structures and contactors (or relays) to improve the fault-tolerant capabilities of power electronics in applications with safety requirements. The suitable combination of these elements gives the inverter the ability to maintain energy processing in the occurrence of several failure modes, including short-circuit in IGBT devices, thus extending its reliability and availability. A survey of previously developed fault-tolerant VSI structures and several aspects of failure modes, detection and isolation mechanisms within VSI is first discussed. Hardware solutions for the protection of power semiconductors with fault detection and diagnosis mechanisms are then proposed to provide conditions to isolate and replace damaged power devices (or branches) in real time. Experimental results from a prototype are included to validate the proposed solutions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1281-1283
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors a net size, weight, and parts cost saying result compared to the other systems due to elimination of 60Hz transformer.