• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권4호
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• pp.201-205
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• 2004

The CCFL dimming control methods are generally used lamp current regulation or average current adjustment method feeding the CCFL inverter. Inverter operation frequency is higher than resonant frequency for safe operation. In this study, we design the half-bridge type series and parallel resonant converter circuit that switches at variable frequency modulation methods to control the output power. This method has advantages such as low EMI and reduced harmonics, and it is convenient for dimming control using a microprocessor. The validity of this study is confirmed from the simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
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• pp.103-108
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• 1996

In this paper, a novel utility connected photovoltaic power generation system with unity power factor and uninterruptable power system facility and its control strategy are proposed. The proposed photovoltaic(PV) system is connected in parallel between utility and load. The PV system provides an uninterruptable voltage to load, a maximum power tracking to solar array, and power factor correction to the utility. The proposed system has the following advantages compared with the conventional utility connected PV system. 1. Harmonic elimination Function 2. Feeding the photovoltaic energy to the utility 3. Providing the uninterruptible power source along battery to the load In case that the photovoltaic array system is on the poor power generation, the battery and capacitor of the PV system are charged by three phase utility source and the inverter in the PV system only provides the reactive current to eliminate the harmonic current exited on the utility. In the normal operation mode, the PV system supplies active power to load and reactive power to utility in order to maintain the unity power factor and to regulate ac load voltage.

• Industrial Engineering and Management Systems
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• 제8권3호
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• pp.155-161
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• 2009

We focus on discrete event systems with a structure of parallel processing, synchronization, and no-concurrency. We use max-plus algebra, which is an effective approach for controller design for this type of system, for modeling and formulation. Since a typical feature of this type of system is that the initial schedule is frequently changed due to unpredictable disturbances, we use a simple model and numerical examples to examine the possibility of applying the concepts of the feeding buffer and the project buffer of critical chain project management (CCPM) on max-plus linear discrete event systems in order to control the occurrence of an undesirable state change. The application of a CCPM-based framework on a max-plus linear discrete event system was proven to be effective.

• 조명전기설비학회논문지
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• 제25권3호
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• pp.40-49
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• 2011

This paper presents novel circuit topology of half-bridge soft-switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed, half-bridge high frequency PWM inverter with a high frequency planar transformer link PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode-equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC bus lines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, high switching frequency IGBTs can actually be selected in the frequency range of 40[kHz] under the principle of soft-switching. The performance evaluations of the experimental setup are illustrated practically.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.291-298
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• 2000

This paper describes a theoretical and experimental investigation into an active vibration isolation system in which four electromagnetic actuators are installed in parallel with each of four passive mounts placed between a piece of equipment and a vibrating base structure. Decentralised velocity feedback control is employed, where each actuator is operated independently by feeding back the absolute equipment velocity at the same location. Although one end of each actuator acts at the sensor positions on the equipment, the control system is not collocated because of the reactive forces acting on the flexible base structure, whose dynamics are strongly coupled with the mounted equipment. Isolation of low frequency vibration is considered where the equipment can be modelled as a rigid body and the mounts as lumped parameter springs and dampers. Control mechanisms are discussed, and some experimental and simulation results are reported.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권3호
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• pp.99-106
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• 2002

This study presents an approach to model the Electric Railway System with the common grounding based on the 8-port network model and to analyse traction power feeding system focused on the amplification of harmonic current. The entire system can be easily modeled by the combination of 8-port representation of each component in parallel and/or series. Through the research, 8-port network model which can be effectively applied to harmonic analysis is derived.

• 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.

• Toxicological Research
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• 제19권3호
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• pp.189-195
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• 2003

The protective effects of BNs-3 and BNs-7, extracts of citrous orange peel, on the obesity induced by ad libitum feeding a cholesterol-containing diet to rats were investigated. The animals were fed on the diet including cholesterol (0.5%) with or without the citrous orange peel extracts BNs-3 (5%) and/or BNs-7 (0.1%) for 8 weeks. The ad libitum feeding a diet containing cholesterol to rats from 6 weeks of age increased the body weight gain compared with that of rats fed on a normal diet. Such an increase in body weights was markedly attenuated by the addition of BNs-3 or BNs-7 to the diet. Especially, a combinational feeding on BNs-3 and BNs-7 significantly reduced the body weight gain below that of normal diet-fed animals. Interestingly, the weights of abdominal adipose tis-sues surrounding epididymides were greatly reduced by the citrous orange peel extracts, in parallel with the decrease in body weights. In addition, blood concentrations of lipids including cholesterol were also lowered by the combinational treatment with BNs-3 and BNs-7. Taken together, it is suggested that the obesity and overweight produced by unrestricted overfeeding on diet with cholesterol may be partially due to the accumulation of abdominal adipose tissues, around the epididymides in rats, and that citrous orange peel extracts might exert antiobese activities by reducing the adipose tis-sues as well as blood lipid concentrations.

• 환경생물
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• 제18권1호
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• pp.145-151
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• 2000

본 연구는 창주둥이바구미과 갑충의 구기가 부드러운 식물조직을 섭식하는 바구미과 갑충과 거의 같은 구조를 하고 있다는 사실을 잘 나타내고 있다. 창주둥이바구미과 갑충에 대하여 주사전자현미경을 사용하여 구기를 본래의 위치에서 관찰하고, 여기에 해부에 의한 연구도 병행하여 얻은 구기구조에 대한 연구의 결과는 다음과 같다. 창주둥이바구미아과의 바구미는 두순 가장자리가 꾸불꾸불한 모양이고, 큰턱은 수축시 전후로 만나며 안쪽으로 약간 굽어있는 구조를 하고 있다. 작은턱 수염은 두마디로 큰 생수절을 가지며, 아랫입술 수염은 한 개의 마디로 되어 있다. 하순전기절은 평행면을 가지며 넓이보다 길이가 더 길다. 별창주둥이바구미아과의 바구미는 두순가장자리 중앙에 2-3개의 홈을 가지고, 큰턱은 수축시 전후로 만나며 안쪽으로 약간 만곡된 구조를 하고 있다. 작은턱 수염은 세마디로 생수절과 첩교절의 크기가 같으며, 아랫입술 수염은 두마디로 하순전기절 꼭대기의 융기에 의해 서로 분리되어 있다. 하순전기절의 넓이와 길이는 같다.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.89-97
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• 2007

This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed half-bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 kHz under the principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for such low voltage and large current DC-DC power supplies as DC bus feeding from a practical point of view.