• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.189-190
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• 2008

최근 국내에서 345kV GIL(Gas Insulated Transmission Lines) 시스템의 실계통 도입이 검토되고 있다. GIL은 지중화 설치가 가능하지만 일반적인 지중케이블과 달리 도체와 외함이 모두 알루미늄으로 되어 있고, 도체 및 외함의 단면적이 매우 크며, 도체전류의 정격 또한 4000[A]에 육박하여 외한에 유기되는 순환전류 역시 상당할 것으로 사료된다. 또한, 접지방식 또한 일반 케이블 시스템과 다르게 되어 있다. 따라서, 본 논문에서는 GIL 시스템의 다양한 접지방식과 부하 불평형 상태를 가정하여 EMTP/ATP 시뮬레이션을 통하여 GIL 시스템의 외함 순환전류 특성을 파악하고자 한다.

• 전력전자학회논문지
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• 제6권6호
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• pp.489-497
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• 2001

병렬로 구성되 UPS 사이에 파라미터 불일치에 따른 순환전류와 전압리플이 발생되어지는데, 이들은 전체 UPS 시스템의 고장 및 신뢰성 저하를 유발한다. 본 논문에서는 이러한 문제점들은 Double 위상동동기기와 능동 다중인 터페이스 리액터를 사용하여 해결하였다. 또한 ADSP21061을 사용하여 제어기를 디지털적으로 구현하였다.

• 전기학회논문지
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• 제66권5호
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• pp.750-756
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• 2017

This paper presents a method for DC voltage control of HVDC system connection of offshore wind farms. In the event of fault in AC grid, HVDC system need to meet LVRT regulations. When HVDC system meet LVRT regulation, unbalance is caused between power input and power output for DC link. Therefore, LVRT regulation lead to DC voltage increase of HVDC system. To control the DC voltage increase, the chopper resistor can be suggested. In this paper, DC voltage suppression is proposed using chopper resistor and de-loading. The effectiveness of the chopper resistor was verified using PSCAD/EMTDC.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.28-32
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• 2007

In this paper, a unified regenerative inverter and control algorithm are proposed in order to perform regenerative action and active power filter action. While the regenerative mode of traction, it works as regenerative inverter to reduce a excessive power of DC bus line and the powering mode of the traction, it works as active power filter to compensate ac current distortion, power factor, and voltage unbalance. In the paper, a regeneration inverter used PWM DC/AC inverter algorithm. And an active power filter used p-q theory. We are carrying out a mode analysis of DC traction system similar to actual system with MG-set and experimenting with prototype model. Through the simulation and experiment, we were proving the regeneration inverter operation which suggested in this paper.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.364-368
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• 2004

A new high efficiency DC/DC converter is proposed, which is derived from the conventional half-bridge converter. The proposed converter has good ZVS condition compared with the conventional half-bridge converter, and shows a high efficiency by solving the unbalance voltage stress and current stress problem of secondary rectifier diode of the conventional half-bridge converter. In this paper, the basic operations of the proposed converter is analyzed compared with that of the conventional half-bridge converter, and the excellent performance of the proposed converter is verified by the experimental results with the 42W prototype of the power supply for PDP Sustain Driver.

• Journal of Power Electronics
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• 제9권3호
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• pp.386-395
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• 2009

In this paper, a new control algorithm for the dynamic voltage restorer (DVR) is proposed to regulate the load terminal voltage during various power quality problems that include sag, swell, harmonics and unbalance in the voltage at the point of common coupling (PCC). The proposed control strategy is an Adaline (Adaptive linear element) Artificial Neural Network (ANN) and is used to control a capacitor supported DVR for power quality improvement. A capacitor supported DVR does not need any active power during steady state because the voltage injected is in quadrature with the feeder current. The control of the DVR is implemented through derived reference load terminal voltages. The proposed control strategy is validated through extensive simulation studies using the MATLAB software with its Simulink and SimPower System (SPS) toolboxes. The DVR is found suitable to support its dc bus voltage through the control under various disturbances.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 추계학술대회 논문집
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• pp.187-188
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• 2014

본 논문에서는 3-레벨 NPC(Neutral Point Clamped) 인버터에서 상단 커패시터 전압과 하단 커패시터의 전압의 불균형 시 나타나는 출력 상전류 왜곡에 대한 보상기법에 대하여 제안한다. 스위칭 기법은 SVPWM(Space Vector Pulse Width Modulation)을 사용하였고 상단 커패시터 전압과 하단 커패시터 전압의 불균형이 DC-Link 전압의 0% 15% 35%일 때의 보상 전과 보상 후를 비교 분석 하여 시뮬레이션으로 출력 상전류 보상기법을 검증하였다.

• Journal of Dairy Science and Biotechnology
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• 제24권2호
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• pp.1-9
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• 2006

Goat milk is digested better than cow milk, because the fat globules in goat milk are smaller and the protein is similar to human milk, and assimilated easily. Goat milk is particularly rich in taurine (4.7mg/100mL) and retinol (40mg/100mL). Therefore, it might be recommened to heal dyspepsia and infants allergy by cow milk. However, during winter, supply of goat milk products are unsteady in Korea, because unbalance of demand and supply is resulted from seasonal breeding. Dairy industry for goat milk will be able to grow much more, if goat milk products can keep steady supply without changing by season. This review includes the physicochemical characteristics of goat milk, domestic production of goat milk, domestic goat milk products and future development.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.11-16
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• 2003

The 3-level converter/inverter system is very efficient in the ac motor drives of high voltage and high power application. This paper proposed a simple method to diagnose faults using change of current vector pattern in space vector diagram when the faults occurrence in the 3-level inverter and a control method that can protect system from unbalance of the neutral point voltage according to faults. The validity of the proposed method is demonstrated by the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1899-1901
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• 1998

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Var Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system. It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.