• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2031_2032
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• 2009

가스절연개폐장치(GIS)에 적용하고 있는 극초단파(Ultra High Frequency, UHF) 전자기파 부분방전 측정기술을 전력용 변압기 분야에 적용하는데 외부잡음 유입특성을 고려하여야 한다. 부싱을 통하여 부분방전 신호 이외의 외부잡음의 유입가능성이 크다. 따라서 본 논문에서는 현장에 설치 운전중인 154kV 변압기에 UHF 센서를 설치하여 부싱을 통해 유입되는 외부잡음을 0~2GHz 의 주파수영역에서 측정 하였다.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.70-76
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• 2017

The standards related to the "Urban Gas Business Act" and the "Safety Control and Business Regulation of Liquefied Petroleum Gas Act" prescribe the separation distance between gas piping joint excluding welded joints and electric equipments(electric switch, watt meter, breaker, connector, etc). The "Korea Electro technical Regulation" also prescribes the distance between gas piping joints and electric equipments in accordance with the gas related standards. In case of the standards related to the "Urban Gas Business Act", the distance criteria stipulated in the standard of supplying facilities are different from those stipulated in the standard of using facilities. In this study, we have conducted pilot test on the possible ignition distance from the piping joint when LP gas is leaked from the point. We have also examined the adequacy of current standards on the separation distance between gas piping joint and electric equipments. As a result of the tests, we have found that ignition is able to occur at a distance of 30 cm as stipulated in the current standards or more when LP gas is leaked from the joint of the pipe. Therefore, we have made a decision that the criteria for separation distance between gas piping joint and electric equipment specified in the current standards related to the "Urban Gas Business Act" and the "Safety Control and Business Regulation of Liquefied Petroleum Gas Act" is appropriate.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.167-176
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• 2014

The pyrovalves are widely used in aerospace industry for the opening and closing of flow channel due to the light-weight, high reliability and zero-leakage. In the United States, the loss of some spacecrafts using hydrazine as the propellent were proven by the blowby. Blowby is defined as the leakage of pyrovalve ignition combustion gas to the flow channel. Since then, the interference fit was applied for the sealing of piston to prevent the blowby. In this study, literature survey on pyrovalve technology is summarized mainly for AIAA papers. Common problems, improvement method, and performance comparisons of pyrovalves are also presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.331-334
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• 2010

Operating characteristics of DGT-5 being developed by Doosan Heavy Industries & Construction Co., Ltd. for power generation service was evaluated. Starting behavior was improved by a series of tests to investigate the effect of various fuel schedule and several combination of bleed valve control. The engine showed stable operation without any instability of compressor in the full operating regime covering from start-up to load conditions. If there is a rapid change of load in the condition of synchronization to Grid, the engine can be controlled stably based on the analysis of dynamic responses of the engine to an rapid load change and a sudden load rejection.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1799-1801
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• 2004

We have developed the external-type PD sensors for detecting of the electromagnetic waves up to ultra high frequency (UHF) bands, propagating in various type of GIS. Sufficiently high sensitivity and accuracy for practical use were achieved for the external PD sensor. The experience at the fields and the criteria for the judgment are also discussed in detail.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1264-1265
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• 2011

본 논문은 가스 절연 차단기를 대체하는 고체 절연체의 성형 시 발생하는 집중 열응력에 의한 고체 절연체의 기계적 특성에 관한 연구 결과이다. 친환경 문제가 대두되고 전기 산업에서 고객은 좀 더 안정적이고 안전한 전기 공급이 필요시 됨에 따라서 고체 절연 개폐기 및 차단기의 수요가 늘어남에 따라 고체 절연체의 생산 불량률이 이슈화가 되고 있다. 특히 성형 시 발생되는 열응력 및 거동으로 인하여 절연체의 균열 및 내부 진공 인터럽터의 파손 등으로 경제적 비용 손실의 문제가 발생하게 되어 집중 응력을 피할 수 있는 합리화 구조에 대한 연구가 진행되었다.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.174-175
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• 2008

초고압 변전소의 주요설비인 가스절연개폐장치(GIS: Gas Insulated Switchgear)의 신뢰도를 높이기 위해서는 절연체 내부에서 발생하는 부분방전을 사전에 진단하여 예방을 하는 것이 중요하다. 현재 이에 대한 진단장치 개발이 이루어지고 있으며 GIS On-line System 장치 및 휴대용 진단장비가 국내에서 제작되고 있으나 On-line System은 고가의 비용이 들고 휴대용 진단장비는 상시감시가 어렵다는 단점을 가지고 있다. 이러한 단점을 보완하기 위해서 본 연구내용에서는 저가이면서 상시 PD 감시능력을 가진 PD 카운터에 대해 설명하고 GIS 현장에 실제 적용한 자료와 휴대용 진단장비와 함께 비교 적용한 자료를 가지고 PD 카운터의 특성을 확인하는데 역점을 두었다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.896-897
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• 2007

산업사회의 발달과 정보통신의 발전 등으로 전송전압이 상승하고 도시의 인구 집중화 현상으로 전력설비의 대용량, 고전압으로 인해 가스절연개폐장치(GIS)의 사용도 증가하고 있다. 이에 따라 GIS를 구성하고 있는 중요부품 중의 하나인 절연스페이서의 사고도 증가하는 추세에 있어 한전 및 국외 사용자로부터 수명보증 등 신뢰성에 대한 공인 시험기관 성적서 또는 인증서가 요구되고 있다. 따라서 본 논문에서는 한전의 표준규격(ES 150-579)에 따른 신뢰성평가기준에 부합되는 냉열시험과 장기과전압시험을 실시하여 절연스페이서의 체계적인 수명평가를 실시하였다.

• Journal of Energy Engineering
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• v.12 no.4
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• pp.253-258
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• 2003

Manual type manifold gauge has been used for charging the refrigerant in the refrigeration systems. In this case, the refrigerant is released to the ambient during the hose-switching period. :he objectives of this study are to develop a novel automatic refrigerant charging system, and to quantify the effect of the automatic systems on the reduction of the non-condensable gas and the contamination of the compressor oil. The automatic charging system makes the pressure test, vacuum test, and refrigerant charging work very simple and easy because the charging hose does not have to be switched many times. It is found that the amount of water in the SiO$_2$and the compressor oil reduces to l/4 times of that for the manual type manifold gauge and the refrigerant is not released to the ambient at all when the automatic charging system is adopted.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.45-51
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• 2015

In order to meet the enforced emission regulations and reduce fuel consumption, various new technologies are employed in engines. The problem of NOx emissions under a lean mixture condition should be solved, because a lean-burn direct-injection engine can realize stable lean combustion with a stratified mixture, which results in improvements in fuel economy and emissions. This study investigated the effects of intake and exhaust valve timing changes on the performance and emission characteristics of a lean-burn LPG direct-injection engine. Under a partial-load operating condition without throttling, an increase in the intake valve opening led to an increase in NOx emissions due to an increase in the amount of excess air. The fuel consumption deteriorated with an increase in the exhaust valve opening due to a decrease in the expansion work and an increase in the pumping loss.