• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2143-2145
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• 2005

Power semicondcutor인 IGBT MOSFET, GTO, SI-Thyristor등은 높은 스위치 신뢰성과 life time, 그리고 fast repetition rate 등을 지니고 있기 때문에 medium/High voltage영역에서 스위치 사용이 대두되어 왔으나, Thyratron이나 Trigatron(Gap switch)와 비교하여 낮은 전압/전류를 스위칭하기 때문에 전통적으로 직렬연결을 통해 high voltage 영역의 스위치로 사용되어 왔다. 하지만, 직렬연결되어 있는 각각의 power semiconductor와 gate driving circuit의 on/off synchronization이 맞지 않기 때문에 부하의 급격한 변화에 따른 전압의 balance에 문제가 가장 심각하게 대두되어 왔다. 이러한 문제를 해결하기 위해서 gate driving circuit에서 제어를 해주는 방법과 power semiconductor에서 제어를 해주는 방법이 있으나 두 방식 모두 문제점이 있다. 본 논문에서는 기존의 zener clamping방식에서 벗어나 새로운 active clamping방식의 직렬연결을 제안했으며 시뮬레이션과 실험을 통해 나타난 이 결과들은 on/off transient 시 symmetry를 유지하는데 효과적이라는 것을 보여주고 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1181-1183
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• 2003

Cold cathode fluorescent lamp(CCFL) are widely used to illuminate the liquid crystal display(LCD). Usually, CCFL dimming methods are used to lamp current regulation or average current adjust feeding the CCFL inverter. Switching frequency of inverter is higher than resonant frequency at stabile states. In this study, design of CCFL driving circuit by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output power. This method has advantages such as low EMI and reduced harmonics. And it is easy to dimming control use microprocessor. The validity of this study is confirmed from the simulation and experimental results.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.74-78
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• 2010

In this paper, 2-axis driving mechanism, which uses voice coil motor (VCM), is proposed to measure the friction force. The proposed VCM actuator consists of two parts; structural part and magnetic circuit part. Structural part is simplified to perform the friction experiments. Magnetic circuit part is composed of two parts. The experiments are accomplished by changing the mass of moving part. Through the experiments, optimal dimension is selected. Finally, the experimental results are verified and the optimal case is applied to the 2-axis driving mechanism, optical image stabilization actuator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.909-910
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• 2007

To design the Molded Case Circuit Breaker(MCCB) requires electromagnetic analysis in contact system when the circuit breakers interrupt fault currents. This paper has made sure that there are two ways increasing arc driving force, one is a change of contact point and the other way inserts additionally the magnetic plate. Finally, we have carried out the analysis of eddy current to identify a decrease of arc driving force because of fault currents. In this paper, MCCB models have been analyzed base on 3D-FEM by Maxwell program.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.279-282
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• 2003

In this paper, to apply piezoelectric transformer for PDA backlight inverter, piezoelectric transformer using the composition which $Nb_2O_5$ added into PNW-PMN-PZT ceramics was fabricated as Rosen-type one with the size of $1165mm^3$. And their electrical characteristics were investigated with the variations of load resistance and driving frequency And then, the driving circuit for PDA CCFL(0.6W) which composed of the two MOSFETs connecting in series was manufactured using piezoelectric transformer, VCO and one-chip microprocessor. After driving for 25 min using the proposed circuit for PDA CCFL(0.6W), driving frequency of 214.4kHz, input voltage of 31.78 V and input current of 21.1mA were shown. And then, output voltage of 293.2 V and output current of 2.2mA were shown. At the same time, efficiency of 96.2$\%$ and temperature rise of $3.6^{\circ}C$ were appeared at the piezoelectric transformer.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.540-546
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• 2005

This paper presents a boost circuit topology driving in high - frequency It solves the problem which arised from hard-switching in high-frequency using a period of resonant circuit and operating under the principle of ZCS turn-on and ZCZVS turn-off commutation schemes. In the existing circuit, it has the high voltage and current stress in free- wheeling diode. But in the proposed circuit, it has voltage and current stress which is lower than voltage and current stress of existing circuit with modifing a location of free-wheeling diode. In this paper, it explained the circuit operation of each mode and the waveform of each mode. Also the experiment results compare the voltage and current stress of free-wheeling diode in the existing circuit with the voltage and current stress of that in the proposed circuit. Moreover, it compares and analyzes the proposed circuit's efficiency with the existing circuit's efficiency according to the change of load current.

• 조명전기설비학회논문지
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• 제18권1호
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• pp.9-14
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• 2004

본 논문에서는 내부 입자의 반경방향 분포와 구동회로를 고려한 형광램프 모델링을 수행하였다. 모델링에서 전자에너지 분포는 Maxwellian으로 가정하였으며, 전자 이동도와 유극성 확산계수는 상수를 사용하였다. 방전 중 수은원자는 6가지 에너지레벨을 갖는다고 가정하였다. 모델을 사용하여 4개의 편미분 2개의 상미분 연립방정식을 FDM과 2계 Runge-Kutta 방법을 사용하여 수치적으로 해를 구하였다. 개발한 모델을 실제 형광램프와 LR안정기 회로에 적용하여 실험적으로 측정한 전압, 전류 파형과 수치해석적으로 구한 전압, 전류 파형을 비교하여, 본 형광램프 모델링의 타당성을 보였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1251-1254
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• 2006

A novel a-Si TFT integrated gate driver circuit using multi-thread driving has been developed. The circuit consists of two independent shift registers alternating between the two mode, "wake" and "sleep". The degradation of the circuit is retarded since the bias stress is removed during the sleep mode. It has been successfully integrated in 14.1-in. XGA LCD Panel, showing enhanced stability.

• 대한기계학회논문집B
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• 제27권4호
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• pp.432-439
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• 2003

In this research, we are trying to develop the new hydraulic driven tire roller which is conventionally operated by mechanical transmission system. The reason why we would like to develop it is that tire roller is one of the most useful machine for the road construction site and also imported totally from overseas. In this paper, we conceptualize the new hydraulic system and derive the equations of motion for dynamic analysis. And we investigate system modeling by using DAQ system. Finally, we will design the controller, which can manage the hydraulic circuit of steering and traction mechanism system. The advent of modern high-speed computers coupled with the application of high-fidelity simulation technology can be used to create “virtual prototypes of construction equipment. Tests conducted on these virtual prototypes may be used to augment actual machine testing, thereby lowering costs and shortening time to production. So, we studied tire roller to integrate development technology. In System Analysis, We formulate hydraulic driving system model and hydraulic steering system model. Also, We integrate DAQ system to acquire experimental result in real tire roller equipment.

• 조명전기설비학회논문지
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• 제25권6호
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• pp.9-17
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• 2011

The high-power LED (Light Emitting Diode) which is recently gaining popularity as a digital light source has such advantages as low power consumption, long life, fast switching speed, and high efficiency. Thus, many efforts are being made to use the high-power LEDs for general lighting. This paper proposes LED driving circuit uses a DC/DC converter that can recover energy to compensate for the current variations caused by changes in LED equivalent resistance following a temperature change instead of serial resistance. The maximum input voltage of this DC/DC converter has low voltage variations by temperature change when the rated current is formed. In order to return current to the input side, we need a high boosting at low power. Thus, to improve the low efficiency of power converter, the power converter can be configured in such a way to gather the powers of low-capacity DC/DC converters and return the total power. Experiments showed that the proposed system improved efficiency compared to the conventional LED drive using the existing DC/DC converter.