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차세대 고속열차용 대차프레임의 건전성 모니터링을 위한 실험적 연구
고재하(Jae-Ha Ko),김상수(Sang-Soo Kim),최성훈(Sunghoon Choi),김석원(Seog won Kim),전흥재(Heoung-Jae Chun) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
The bogie is one of the most important components in a railway vehicle. So a lot of study has been carried out for safety and reliability of the bogie frame in experimental and simulation. In this paper Presents an experimental study on health monitoring of next generation high-speed train bogie frame. The ultimate objective of this paper is to estimate the sensor located for health monitoring of bogie. The result from this study might be used essential data in order to construct the next generation high speed train bogie frame health monitoring.
방전램프의 역률 보상용 콘덴서를 이용한 저가형 LED 구동회로
고재하(Jae-Ha Ko),황정구(Jung-Goo Hwang),박성미(Seong-Mi Park),박성준(Sung-Jun Park) 한국조명·전기설비학회 2013 조명·전기설비학회논문지 Vol.27 No.3
Now it’s a trend to install a series of white fluorescent light and orange high pressure sodium lamps because tunnel lighting should be opaque to the safety of drivers from soot, dust, humidity, and fog. Also fluorescent lighting is replaced to LED due to the fact that it improves amenity and object recognition and LED lighting has gradually been improved its nature. In this paper, we have implemented the circuits of the yellow series of high-pressure sodium lamps and white series of LED lights at one board to improve the transparency and recognition of objects. It is possible for inductive high-pressure sodium lamps and the capacitive LED drivers to circuit without power factor compensation. Two circuit parts share only a small number of parts, so low cost LED drivers compared to conventional ones are possible. Therefore, the implementation of the hybrid lighting with high-pressure sodium lamps and LED lights that can be driven at the same time by one driving circuit is possible. The LED capacitive power factor was 0.91 while individually implemented the sodium lamp power factor was 0.98. It shows not only the 2% improvement of hybrid forms but also the efficiency and THD.
정대원(Dae-Won Chung),고재하(Jae-Ha Ko),윤근영(Keun-Young Yoon) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.5
최근 인공지능 딥러닝(AI Deep Learning, DL) 기법은 공학 분야의 모델예측과 진단방법으로, 그 정확성이 검증되고 인증되면서 다양한 분야에서 그 우수한 성능을 발휘하고 널리 활용되고 있다. 본 논문에서는 이런 점에 착안하여 전력수요의 최적 관리를 위해 단기전력 수요예측 모델에 적용하는 방안을 제안한다. 단기간 전력수요 예측은 전력수요관리 측면에서 중요하나 그 정확성이 낮아서, 보다 우수한 성능 기법이 요구되었던 점에 비추어 적용성이 매우 높고, 기존의 방식에 비해 보다 우수한 성능과 정확한 전력수요관리가 가능하다. 특히 특정지역의 수용가의 사용된 전력량의 데이터를 바탕으로 전력수요 예측을 적용하였다. 또한 전력수요의 평균절대백분비오차(MAPE)를 비교하여, 전력수요 예측 결과의 정확성과 타당성을 검증하였다. 이를 통해 전력수요 변동에 따른 단주기 전력수요 예측 모델의 구현성 및 향후 활용 가능성을 확인하였다.
동기 스위치 정류 방식을 이용한 고효율 태양광발전 역전류방지장치에 관한 연구
나정승(Jeong-Sueng Na),고재하(Jae-Ha Ko),강신영(Sin-Yeong Gang),박성미(Seong-Mi Park),박성준(Sung-Jun Park) 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.1
Recently, due to a fire caused by old photovoltaic MJB(Module Junction Box), a situation that paralyzes the photovoltaic system has frequently occurred. Most of the heat sources which cause a fire in the inside of MJB are several to dozens of the diodes preventing the reverse flow of current connected in series to each string. A heating loss occurs due to the forward voltage of the diodes. If the heating loss occurring in the diodes can be reduced, the size of MJB can be reduced. The closed MJB which is able to block sufficiently oxygen supply to an MJB will be very helpful for fire protection. Therefore, this study proposes high-efficiency photovoltaic reverse-current protection device using the synchronous switching rectification method which can greatly reduce the heat generated from the general diodes preventing the reverse flow of current in a photovoltaic MJB.
장순석(Sun Suck Jarang),고재하(Jae Ha Ko),이제형(Je Hyeong Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The directivity of the sound pressure increases the sensitivity of the incoming sound from specific directions. The directivity measurement of the sound pressure is usually done in an anechoic room using a steping motor. In this paper a replaceable anechoic chamber was designed for the acoustic directivity pattern measurement. Electrical equipments were interfaced with a PC for experiment automatic control. Some comparative results are shown in the result.