• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.948-949
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• 2008

In this paper, an effect on power conversion unit in next generation high-speed train by loss of contact between a contact wire and pantograph supplied electrical power to high-speed train are investigated. One of the most important needs accompanied by increasing the speed of high-speed train is reduced that arc phenomenon by loss of contact brings out EMI. To analysis of conducted EMI source on powering mode of next generation high-speed train, it is necessary electrical modeling system between the contact wire and the pantograph according with loss of contact. Therefore analytical model of a contact wire and a pantograph is constructed to simulate the behaviour of loss of contact. The reliability of the modeling system is verified by simulation implementation on loss of contact.

• 전력전자학회논문지
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• 제11권3호
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• pp.216-223
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• 2006

태양광 발전 시스템을 위한 무접점 변압기 적용 고효율 Full-bridge LLC 공진컨버터를 제안하였다. 제안된 LLC 공진컨버터는 직렬 커패시터와의 직렬공진을 위해 무접점 변압기의 누설인덕턴스와 자화인덕턴스를 이용하였다. 제안된 LLC 공진컨버터는 공진주파수 보다 높은 스위칭영역에서 연속 공진전류로 동작하는 기존 직렬공진 컨버터와는 달리 공진주파수 아래의 좁은 주파수 범위에서 불연속 공진전류로 동작한다. 이러한 불연속모드 공진전류 때문에 제안된 컨버터는 어떤 보조회로 없이 무접점 변압기 1차측 주스위칭 소자의 영 전압 스위칭(ZVS)과 2차측 다이오드의 영 전류 스위칭(ZCS)을 얻을 수 있고, 높은 전압이득특성을 갖는다. 본 논문에서는 무접점 변압기 적용 Full-bridge LLC 공진컨버터를 이용한 무접점 전원장치에 대한 이론적 해석 및 시뮬레이션을 통해 150W급 시제품을 제작하여 태양광 발전 전원시스템에 적용 실험한 결과를 서술했다.

• 한국안광학회지
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• 제20권2호
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• pp.105-115
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• 2015

목적: 본 연구는 안경렌즈홀더와 콘택트렌즈홀더를 사용하여 다양한 디옵터와 함수율을 가진 소프트 콘택트렌즈의 굴절력을 측정하고 정확도를 평가하여 그 차이를 비교하였다. 방법: 실험에 사용한 소프트 콘택트렌즈의 함수율은 각각 38%, 43% 및 58%이었으며, 굴절력에 따라 -3.000 D, -7.000 D 및 -10.000 D로 분류하여 각각 실험하였다. 또한 망원경식 렌즈미터를 사용하여 안경렌즈홀더 및 콘택트렌즈홀더로 각각의 정점굴절력을 측정하여 정확도를 분석하였다. 결과: 안경렌즈홀더를 사용한 경우 -3.0000 D는 -3.3273 D로 측정되었으며, -7.0000 D는 -7.1306 D, -10.0000 D는 -10.2944D로 각각 측정되었다. 또한 콘택트렌즈홀더를 사용한 경우 -3.0000 D는 -3.1060 D로 측정되었으며, -7.0000 D는 -7.0028 D, -10.0000 D는 -10.2611 D로 각각 측정되었다. 모든 종류의 콘택트렌즈에서 콘택트렌즈홀더를 사용한 방법이 안경렌즈홀더를 사용한 방법보다 더 정확한 측정값을 나타내었다. 결론: 위 결과로 볼 때, 망원경식 렌즈미터를 사용한 소프트 콘택트렌즈의 굴절력 측정에 있어 콘택트렌즈홀더를 사용한 방법이 안경렌즈홀더를 사용한 방법보다 더 높은 정확도를 가진 것으로 판단된다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권8호
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• pp.438-444
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• 2000

We report the effects of etch process parameters on the ohmic contact formation in the plasma etching of GaN. Planar inductively coupled plasma system with $CH_4/H_2/Ar$gas chemistry has been used as etch reactor. The contact resistance and the specific contact resistance have been investigated using transfer length method as a function of RF bias power and %Ar gas concentration in total flow rate. AES(Auger electron spectroscopy) analysis revealed that the etched GaN has nonstoichiometric Ga rich surface and was contaminated by carbon and oxygen. Especially large amount of carbon was detected at the sample etched for high bias power (or voltage) condition, where severe degradation of contact resistance was occurred. We achieved the low ohmic contact of $2.4{\times}10^{-3} {\Omega}cm^2$ specific contact resistance at the input power 400 W, RF bias power 150 W, and working pressure 10mTorr with 10 sccm $CH_4$, 15 sccm H2, 5 sccm Ar gas composition.

• 전력전자학회논문지
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• 제17권5호
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• pp.445-452
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• 2012

The impurity detection method applied to existing discriminated the normality(R, L, C) and impurity(Metal) load using mutual RFID/ID method in the contactless power supply in which the primary side and the secondary side are completely separation by using the contactless transformer. However, this kind of system is caused the high cost of the system and complexity of control. Therefore, in this paper was proposed the contact-less power transfer using the primary current that determine normality or impurity load by compare the primary current Amplitude to reference quantity value and design the 3[W] contact-less power transfer and conduct an experiment for demonstrate the validity.

• 한국전기전자재료학회논문지
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• 제23권8호
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• pp.632-637
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• 2010

The measurement of contact wire wear in electric railways is one of the key test parameters to increase speed and maintain safety in electric railways. Wear caused by continuous interaction between pantographs and contact wires has a negative effect on current collection quality and severely damaged contact wires might cause hazardous accidents. This paper introduces a non-contact optical-based contact wire wear measuring system that will replace conventional wear detecting methods conducted by maintenance vehicles or workers. The system is implemented by high-speed cameras that can collect images of contact wires during vehicle operation, a laser used to create images profile of the contact wire surface, and a computer used to process the collected images. The proposed system is designed to assist maintenance of overhead contact lines by creating geometrically plotted images of contact wires to detect contact wire wear during operation on conventional lines or high-speed lines.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1044-1048
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• 2006

Nuclear power generation is very dangerous in occasion that skirt of structure by earthquake although it is high effective generation that can make a lot of energies with few raw material. when design, it must consider a lot of problems caused by an earthquake. The seismic analysis of the structure has been great concern in the engineering society with an effort to reduce the severe damages from an earthquake. So the earthquake resistant design is one of the crucial design procedures of a gate valve used in nuclear power generation. The gate valve which has the contact area between stem and bellows. Because of the contact area. The gate valve should be given high stress and frictional wear. In this thesis, Considering the gate valve which has some contact distance between stem and bellows. The gate valve which has some contact distance is analyzed by a commercial FEM code of Ansys and Then compared to the gate valve behavior which doesn't have contact distance.

• 한국인터넷방송통신학회논문지
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• 제15권6호
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• pp.231-238
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• 2015

본 연구는 RF 마그네트론 스퍼터링을 이용하여 ITO glass 위에 N-Type과 P-Type 박막을 증착하여 증착조건에 따른 면저항 특성을 확인하였다. N-Type의 I-V특성은 RF Power가 150 W 일 때 전류의 값이 가장 높은 것으로 나타났고, 15분을 증착하였을 때 기울기가 일정하게 나타나면서 Ohmic contact이 잘 이루어지는 것을 확인 할 수 있었다. 기판온도와 RF Power 및 증착시간이 증가함에 따라 면저항이 증가하는 것으로 나타났고, 면저항이 작은 값일수록 I-V 특성이 잘 나타났다. P-Type 에서도 N-Type과 비슷한 양상을 보이는데, RF Power가 150 W일때 전류가 가장 높은 것으로 나타났고, 20분을 증착하였을 때 Ohmic contact이 잘 이루어지는 것을 확인 할 수 있었다. 면 저항 또한 N-Type과 비슷하게 RF Power와 증착시간이 증가함에 따라 면저항이 증가하는 것을 확인 할 수 있었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.323-324
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• 2014

A higher-order power converter topology for an extremely low coupling (less than 0.15) transformer with high efficiency and wide air-gap (23 mm) is presented in this paper. Among the typical resonant converter topologies for contact-less power transferring systems, Series-Series Resonant Converter (SSRC) and Series-Parallel Resonant Converter (SPRC) are widely used in number of power electronic applications. However, when coupling coefficient of a transformer is seriously low (k<0.5), the series-series resonant converter will possibly operate at short circuited condition because of the small magnetizing impedance. To solve this problem, a modified and improved topology of seventh-order resonant converter for contact-less power converter system is proposed and the results are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.109-110
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• 2007

Most transmission lines pass through mountainous terrain and deep valleys, to avoid populated areas. Accordingly, the impact of climate changes, environmental conditions and system expansion have caused an increase in transmission line system fault rates. KEPCO has developed and applied phase-spacers to reduce contact faults between phases. Contact between phases represented 9% of total line faults before the devices were installed. Phase-spacers have reduced faults by up to 3.4% since the phase-spacers were installed in 2005. Also, recently developed devices provide additional economic benefits as they cost about a third of the price as similar devices introduced in foreign countries. Phase-spacers are an effective way to prevent phase contact accidents by maintaining physical space between phases. These spacers will be implemented in areas where contacts are likely to occur. They are expected to reduce accident rates and improve power quality.