• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.117-122
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• 2005

This paper proposes an inverter for the grid-connected photovoltaic system based on the transformer-less inverter. This system consists of a high frequency converter bridge, high frequency transformer, diode bridge rectifiers, a DC filter, a low frequency inverter bridge, and an AC filter. The high frequency converter bridge switching at 20kHz is used to generate bipolar PWM pulse, and the high frequency transformer raise its voltage twice, which is subsequently rectified by diode bridge rectifiers to result in a full-wave rectified sine wave. Finally, it is unfolded by a low frequency inverter bridge to result in a 60Hz sine wave power output. Even though the high frequency link system needs more power semiconductors, a reduced size, light weight, and saved parts cost make this system more comparative than the other systems due to elimination of 60Hz transformer.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권3호
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• pp.182-188
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• 2006

Contactless power system is base on power transmission by magnetic force. The transformer loss is large because it separated with the gap. Also the system has unstable factor, since the parameters in the secondary can vary with the system movement. This paper proposes light train power transmission system using contactless transformer with multiple primary winding. To increase the system efficiency and to obtain the stable power transmission to the dynamic load, a resonant inverter is adopted. The proposed system was verified by the simulation using Spice and Maxwell. The designed contactless power transmission system is implemented for 5[kW] class and experimental results are discussed.

• 센서학회지
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• 제32권1호
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• pp.55-61
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• 2023

The objective of this study is to determine the concentrations of mixed gases by establishing a diagnosis method of a transformer using tunable-wavelength optical infrared sensors. Absorption of infrared light by methane, acetylene, and ethylene gases injected is measured from the outputs of the infrared sensors. Regression analysis equations of the gas concentrations are acquired from their respective measured absorption. The obtained concentrations are as follows: -3-9 % errors above 600 ppm(methane), 3 % errors above 1200 ppm(acetylene), and 10 % errors above 500 ppm(ethylene). The concentration inference equations obtained using the individual gases are applicable when the absorption wavelength bands do not overlap. The results of the fault analysis of a transformer using the Duval triangle method and the tunable infrared gas sensors are as follows: temperature faults with -1-1% errors and energy faults with -7-7 % errors.

• 전력전자학회논문지
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• 제7권6호
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• pp.563-569
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• 2002

본 연구는 60Hz 절연변압기가 없는 형태의 고주파링크방식의 계통연계형 PCS(Power Conditioning System)를 개발하였다. 본 시스템은 고주파 DC-DC 컨버터, 고주파 절연변압기, 풀브리지 다이오드 정류기, DC filter, 저주파 인버터, LC 필터로 구성되어 있다. 고주파 DC-DC 컨버터는 20kHz의 bipolar PWM 펄스를 발생시키며, 이 펄스는 고주파 절연변압기를 통해 승압되고, 풀브리지 다이오드를 통해 정류된다. 마지막으로 저주파 인버터를 통해 정현파 전류가 계통에 유입되게 된다. 제안한 고주파링크방식의 시스템은 기존의 60Hz 절연변압기를 사용하는 시스템 보다 많은 스위칭 소자가 사용되지만, 60Hz 절연변압기를 생략함으로서 시스템의 소형경량화 및 저가화를 이룰 수 있었다.

• 마이크로전자및패키징학회지
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• 제11권2호
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• pp.37-41
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• 2004

LCD TV의 백라이트로서는 cold cathode flourescent lamp (CCFL)를 병렬로 구성한 직하방식의 백라이트 많이 사용되고 있다. 현재 각 각의 CCFL에 transformer 한개 씩을 사용하여 일정한 전류를 공급함으로서 백라이트의 균일도를 얻고 있으나 본 논문에서는 differential driving inverter를 이용하여 transfomer에 8개의 램프를 연결하여 구동함으로써 transformer의 개수를 현저히 줄일 수 있었다. Differential driving 방법을 이용하여 transformer 2개를 사용한 인버터를 제작하였으며 이를 이용하여 길이 450mm, 관경 4mm의 CCFL 16개를 사용한 26"용 LCD TV 백라이트를 구동할 수 있었다. 개발된 differential driving 인버터를 이용하여 백라이트를 구동한 결과 $88\%$ 이상의 휘도 균일도를 갖는 백라이트를 구현할 수 있었다.

• KIEAE Journal
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• 제2권1호
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• pp.49-54
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• 2002

Solar daylighting system provides free and comfort lighting, but its cost has been key issue due to difficult design and control of the heavy light collecting system. One of the solutions for the heavy design issues would be using a light framed film such fresnel and prism lens. Prism light guide luminaires have for some time been used to distribute light when it is desirable to have remote light sources. These systems are helpful when it is desirable to have fewer light sources, and/or to position light sources in places where lamp maintenance is easier, or electrical hazard is reduced. This proposed prototype system consists of light collector, light transformer and light pipe.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.97-101
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• 2002

The optical current transformer using Faraday effect is the sensor to measure current that flows in any conductor. This sensor doesn't undergo the magnetic saturation and effect of adjacent conductors. But this senor using bulk-glass sensing element has crucial drawback. It is impossible that the sensor is mounted to conductor without breaking the closed-loop of light or conductor. So we developed the clamp-type optical current transformer and made an experiment.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.26-32
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• 2013

The LED has the proportional characteristic between the flux of light and its current and has caused voltage-current deviation on production process. Thus the unbalancing of each LED strings current occurred by its characteristic deviation. This unbalancing reduce a uniformity of the flux of light. Therefore, we researched to design method the LED driver based on DSP and the balancing transformer for a LED current balancing. These are applied to 50W LED module consist of 4 parallel strings. We analyzed the reduction of LED currents unbalance by experimental result from each method.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권9호
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• pp.407-413
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• 2005

The optical current transformer was developed for 170 kV GIS using optical fiber. The sensor optimized on the optical CT was wound 3 turns and twisted 4 times per a turn at the pipe with a diameter of 130 m. To optimize the optical CT, the output signal was measured according to the setting angle of polarizer and analyzer, The asymmetry and distortion of the output signals were improved when the parallel polarized light was incident to the fiber sensor and under the angle of analyzer was $45^{o}$. The measurement error for the linearity was only $\pm{0.42}\;\%$ to 1,000 A in the case of reflection type.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.60-65
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• 2003

본 논문에서는 Faraday 효과를 이용한 클램프형 구조의 광-전류 변류기 헤드 설계시에 고려해야할 조건을 이론적으로 해석하고, 이를 토대로 한 클램프형 광-전류 변류기 헤드를 제작하여, 도선에 흐르는 전류, 광의 입사각에 따른 광출력의 변화 및 감도를 측정하고 분석함으로써 전류계로서의 가능성을 입증하였다.