• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.178-181
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• 2007

본 논문에서는 연료전지자동차의 저전압 배터리 충 방전을 위한 3상 양방향 DC-DC 컨버터를 제안한다. 제안한 3상 컨버터는 기존의 단상 컨버터에 비해 인터리빙 효과의 증대로 인한 입 출력 필터 사이즈 감소와 변압기의 이용률 증가로 인한 VA정격의 감소가 가능하다. 고전압 측에서는 비대칭 소프트 스위칭이 되고, 저전압 측에서는 동기정류 방식으로 도통손실을 감소시켜 높은 효율과 전력밀도를 가질 수 있다. 제안하는 3상 양방향 DC-DC 컨버터의 동작원리와 기존방식과의 비교 분석을 수행하였으며 시뮬레이션을 통해 타당성을 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.15-22
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• 2014

Recently, parallel operation of dc-dc converters has been widely used in distributed power systems. In this paper, a control method to achieve parallel operation of three-phase bi-directional isolated interleaved dc-dc converters is discussed for the battery charging and discharging system which consists of the 32 battery charger/dischargers and two three-phase bi-directional isolated interleaved dc-dc converters. In the boost mode, the battery energy is delivered to the grid, whereas the grid energy is transferred to the battery in the buck mode operation. The average current sharing control method is employed to obtain an equal conducting of each phase current in the three-phase dc-dc converter. By using the proposed method, the imbalance factor is gratefully reduced from 8 percent to 1 percent. Two 2.5kW three-phase bi-directional dc-dc converter prototype have been built and the proposed method has been verified through experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.12
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• pp.996-1001
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• 2011

A bushing is very important because it must supply the high voltage to the power equipment. Generally, the surface of bushing is contaminated with rain, dust, salt and others. A bushing with contaminations at air are serious problem in insulation. Therefore, it is important to understand the inspection and diagnoses of the safety. The ultra-violet rays(UV) camera has attracted interest from the view point of easy judgement. In this paper, we will report on the corona discharge characteristics on bushing model with contaminations. Also, UV images of discharge in air are analyzed using prototype UV camera of Korea. These results are studied at both AC and DC voltage under a non-uniform field.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.112-116
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• 2007

In this paper, we proposed a selection and application recommendations of ZnO arresters for DC electric traction vehicles. To decide the Continuous Operating Voltage($U_C$), the Rated Voltage($U_r$), and the Nominal Discharge Current(In), we measured and analyzed system voltages and surge currents flowing the arrester installed on a DC electric traction vehicle under running state. System voltages measured up to 1,800 V in 1,500 V-system, and surge currents were recorded up to 3 times per a running-service-route and their magnitudes were ranges of $150A{\sim}2kA$. From these results and a standard EN50163, we could proposed $U_C$, $U_r$, and In available for the 1,500 VDC electric traction vehicles.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1382-1384
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• 1995

In order to study the structure of RF glow discharge driven at 13.56MHz in argon, the discharge voltage, current and phase shift between them will be measured over a wide range of discharge parameters(gas pressure between 1mTorr and 50mTorr with discharge power between 20mW and 200W). In this paper, the dc glow discharge characteristics and plasma parameters of both FTS and CPMS systems are studied experimentally. It is found that for CPMS system discharge is stablized under wider ranges of magnetic field and pressure than for FTS system. The plasma density and electron temperature of the plasma for these two systems are in the range of $10^{10}{\sim}7{\times}10^{11}[cm^{-3}]$ and $3.5{\sim}6.5$[eV], respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.156-161
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• 2004

In this research, we used discharge tube without dielectric bead or with dielectric beads(SiO$_2$, $Al_2$O$_3$, or ZrO$_2$), and discharge in water at High-voltage pulse$.$DC power supply for removal of Escherichia coli. At the result of experiments, the removal characteristics of Escherichia coli appeared relation ratio to input voltage. Because, the electric field of discharge tube is increased when input voltage is increased. And, discharge tube used dielectric bead(ZrO$_2$), the removal characteristics of Escherichia coli was better than cases of else. And discharge used DC Power, the removal characteristics of Escherichia coli was better than AC Pulse Power.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1788-1794
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• 2011

The mold transformer is a complex and critical component of DC substations in Metro system. In this paper, a cost effective and intelligent condition monitoring system for mold transformers in DC substations was developed. This paper also provides an overview of the management program using PD (partial discharge) data on mold transformers. Prior to application of the proposed system to Metro DC substations, experiments were performed at the metro line substation located in Seoul and presented case studies for the use of the intelligent condition monitoring system for mold transformer in DC substations. The experiment results indicated that the developing system can be need in helping mange the risk of unexpected failure of mold type transformers.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.677-680
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• 2009

DC influence between pixel electrode and alignment layer (AL) in in-plane switching mode LCD was analyzed through DC equivalence-circuit equation induction, DC charge-discharge simulation, luminance and residual-DC measurement systems using test patterned (TP) cell. DC discharging rate (DDR) of single layer electrode was faster than that of double layer electrode and DDR of low resistance AL was faster than that of high resistance AL. DC discharging characteristics had a close relation to layer number and resistance between two electrodes.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.105-106
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• 2000

The positive slope of the current-voltage characteristic at pressure up to 850 torr was obtained using the closed microhollow cathode without the individual and/or distributed ballast. This indicates that the stable parallel operation of the discharge was also achieved using the closed microhollow cathode. The parallel operation makes it possible to manufacture de plasma displays with high pressure, small discharge current, and long lifetime.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.55-59
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• 2003

본 연구에서는 새로 고안된 DC방전 AND gate를 구성하는 각 방전셀 상호간의 영향을 방전특성 측면에서 규명하였다. 4개의 각 셀은 서로 공간전하와 결합하여 깊은 연관이 있었으며 그 결과 PDP의 address 방전을 도와주기 위한 프라이밍 방전의 동작마진을 얻기가 매우 어렵다는 것을 정성적으로 알았다. 실험결과 각 전극의 최적화된 방전전압을 결정할 수 있었다.