• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.211-213
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• 2009

This paper was studied about the ultra-violet rays(UV) image area and discharge quantity of 22.9kV class polymer insulator using UV camera. The UV image area was begun to observe to 60kV that is about 40% of breakdown voltage of polymer insulator and the area was increased by applied voltage. Also, the discharge quantity was increased at 60kV sharply. If the intensity of breakdown passes over about 40% we can know that need the check on the electrical facility.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.568-570
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• 2008

본 논문은 이차공기송풍기를 가변 회전수 제어하여 소내 소비 전력을 절감하고, 전동기의 직입기동에 의한 스트레스를 줄이기 위하여 실증 적용된 발전소 이차 공기송풍기 구동용 H-브릿지 멀티레벨 인버터에 관한 것이다. H-브릿지 멀티레벨 인버터는 독립적으로 절연된 직류 부를 갖는 저압의 단상 인버터(셀 인버터)를 다수 직렬 접속하여 고압 3상 전압을 출력하는 Cascaded H-브릿지 전압형 인버터이다. 주요내용은 국산 인버터 발전소 현장적용 기술을 바탕으로 대형 인버터 현장 실측 내용과 적용시의 문제점들을 다루어 발전소에 확대 적용에 도움을 주고자한다.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2124-2125
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• 2006

실세계의 복잡하고 종합적인 정보를 빠르고 효율적으로 분석 처리할 수 있는 지리정보시스템(GIS : Geographic Information System)의 효용성이 인식되면서 전력산업에서도 전국의 시설물 관리를 위해 수치 지리정보를 구축하였다. 한편, 약 10만호의 고압고객을 대상으로 15분 단위의 전력사용량을 무선통신망을 이용하여 자동원격검침(AMR: Automatic Meter Reading)하고 있다. 본 논문에서는 산재된 대용량의 AMR 시계열성 데이터와 공간성을 지니는 배전계통 지리정보 데이터를 이용하여 회선 및 구간별 상세한 부하패턴 분석, 공간적 부하분포 및 특성 분석을 할 수 있는 새로운 활용모델을 개발하고 그 결과를 제시하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.395-399
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• 2003

In this paper, physical phenomena which are related to the high temperature and high pressure arc plasma generated during the fault current interruption by SF6 gas circuit breakers are reviewed. In particular, in order to analyze nozzle ablation induced by the heats transferred to the surface of the poly-tetrafluoroethylene(PTFE) nozzle through arc radiation, a governing equation for the calculation of PTFE concentration is added to the governing equations for SF6 arc Plasma analysis. The proposed method is applied to the steady state analysis of $SF_6$ arc plasma generated by direct current taking account of the nozzle ablation and the results are presented.

• Journal of the Korean institute of surface engineering
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• v.39 no.5
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• pp.229-234
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• 2006

Diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization method. Therefore, we need to develop a new identification method that is non-destructive, fast, and inexpensive. We proposed using new methods of UV fluorescence and X-ray Lang topography for checking the local HPHT stress field to distinguish these diamonds from natural ones. We observe unique differences in the local stress field images in treated diamonds using UV fluorescence and Lang topography characterization. Our result implies that our proposed methods may be appropriate for identification of the treated diamonds.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.259-261
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• 2007

논문은 동해화력발전처의 이차공기송풍기를 가변 회전수 제어하여 소내 소비 전력을 절감하고 전동기의 직입기동에 의한 스트레스를 줄이기 위하여 실증 적용된 동해화력발전처 이차 공기 송풍기 구동용 H-브릿지 멀티레벨 인버터에 관한 것이다. H-브릿지 멀티레벨 인버터는 독립적으로 절연된 직류 부를 갖는 저압의 단상 인버터(셀 인버터)를 다수 직렬 접속하여 고압 3상 전압을 출력하는 Cascaded H-브릿지 전압형 인버터이다. 본 논문에서는 동해화력발전처에 실증 적용된 6.6kV, 1MVA급 인버터의 계통 병입 후 부하 변동 시험을 통하여 신뢰성을 입증하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1848-1849
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• 2007

배전계통과 설비의 부하분석은 계측장치에 의존하여 왔으며, 대규모인 배전설비의 부하감시는 막대한 설치 및 유지보수 비용이 수반된다. 본 논문에서는 계측장치를 설치하지 않고도 정기적으로 취득되는 고객의 검침데이터를 이용하여 배전설비의 시간대별 부하분석 및 시뮬레이션을 수행할 수 있는 모델을 개발하고, 그 과정 및 결과를 제시한다. 이 모델은 고압고객의 원격검침 및 저압고객의 월검침 데이터를 구간계통에 적용하고 조류계산을 수행하여 15분 단위로 회선이하 구간 및 변압기의 부하를 분석할 수 있다. 또한, 특정 시점의 부하를 증감시키거나 다른 설비로 전환하여 시간대별 부하가 어떻게 변화하는지 시뮬레이션을 수행할 수 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.433-436
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• 2011

The effect of plasma on flow characteristics in subsonic flow in backward-facing step is studied. The velocty of main flows are 0.5 m/s. DBD plasma is using for flow control. Stainless foil and polymide films are used as an electrode and dielectric material. The change of flow characteristics are shown by different of plasma generation region in fluid flow.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.122-129
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• 2016

In this study, we developed a pressing device which can reproduce the pressure of concrete inside the conveying pipe as a part of the basic study to development of high fluidity concrete under high pressure pumping. Using this pressing device, we evaluated a absorption properties of aggregate that are crushed coarse aggregate, river gravel and lightweight coarse aggregate according to pressure of coarse aggregate and aggregate inside a high fluidity concrete, focused on the reduction of unit water quantity by pressure. In addition, it was evaluated the compressive strength of high fluidity concrete about before and after of pressive. Test a result, case of condition under the high pressure of 250 bar, absorption ratio of crushed coarse aggregate and river gravel were not increased above the surface absorption, absorption ratio of lightweight coarse aggregate was increased than the surface absorption.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1061-1066
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• 2011

In this study, the flow characteristics of an injection nozzle installed in a high-pressure holder for improving productivity were determined. The inlet velocity, nozzle inflow angle, and nozzle outlet diameter were selected as design factors having an influence on the flow characteristics, and numerical analysis was conducted for these factors. As the inlet velocity is high and the nozzle outlet diameter is small, the pressure and velocity of the injected flow are high. In the case of the nozzle inflow angle, the variation of flow characteristics according to angle was slight, but the highest pressure and velocity were found at $15^{\circ}$. In addition, the possibility of chip elimination by the injected flow was analyzed on the basis of the numerical results.