• 전력전자학회논문지
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• 제5권5호
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• pp.501-507
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• 2000

형광등용 전자식 안정기의 개발에 있어서, 최근 선전류 고조파 성분의 제한에 관한 여러 가지 규제를 만족시키기 위해 역률 개선 회로를 부가하는 것이 권장되고 있다. 본 논문에서는 자려식 전류원 방식 푸시-풀 공진형 인버터의 전력 트랜스포머의 2차측과 별도의 한 개의 커패시터를 사용함으로써 역률 개선을 수동소자로만 이용하여 전류원 방식의 공진형 인버터를 채택하는 형광등용 전자식 안정기를 저가격화, 고역률화하는 것을 목적으로 한다.

• 한국보건간호학회지
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• 제7권2호
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• pp.67-76
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• 1993

This study was conducted to investigate the nurses' recognition extent of nursing power and related factors. It was performed in a private university hospital using questionaire papers from Jul. 11 to Jul. 20, 1993. The collected data were in number of 209, and they were handled and analyzed by computer program (SPSS). Through above process, we got meaningful results as follow. 1. The factor concerned with whether the nursing department show its independent power or not was 4.1 on an average. Consequently above results showed that the independent power roles as a important factor. The factor concerned with study and research was 3.9 on an average. So that the extension of learning was also a comparatively important nursing power. But ensuring good material environment was merely 1.6 on an average. So it was understood as less important nursing power. 2. Between the factor concerned with enforcement of independence of nursing department and the factor concerned with extension of learning, there was positive correlation of 0.32 Pearson's Correlation Coefficent. It can be interpreted as the effort of extension of learning go side by side with the showing of independent power of nursing department. As a result the power of nursing become strong. And between the factor concerned with enforcenment of independence of nursing department and the ensuring o(good material environment, there was negative correlation of -0.28 Pearson's Correaltion Coefficint. It can be interpreted as the stronger the independent power of nursing, the more overlooked the recognized of material environment of nurses.

• 에너지공학
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• 제22권3호
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• pp.283-286
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• 2013

전력사업자의 요청, 경제적인 요인 또는 기타 요인에 따라 기존 발전소의 설계개념 변경 없이 발전소의 전기출력을 증가 또는 감소시켜 발전소를 재설계하는 경우가 종종 있다. 이때 노심출력 및 전기출력을 변경시켜 재설계되는 발전소의 설비들의 가격을 예측할 경우, 시장에서 견적을 받을 환경이 아닐 경우에는 기존발전소 설비들의 가격에 비용보정계수(Cost Scaling Factor)를 적용하여 새로 설계되는 발전소 설비들에 비용들을 계산할 수 있다. 이에 미국의 DOE, EPRI, ABB, SWEC 기관들의 발전소 용량변경에 따른 비용보정계수를 검토하고, 그것을 국내 PWR 1000MWe, 1400MWe에 적용한 결과를 소개하고자 한다.

• 산업기술연구
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• 제25권B호
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• pp.195-202
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• 2005

The rectifier characteristics and the quality of the input current worsens with the increase of unbalances or harmonics of the supply voltages. Rectifier input current harmonics interfere with proper power system operation, reduce rectifier power factor, and limit the power available from a given source. It is of importance to select appropriately the rectifier's output filter inductance to determine the rectifier input current waveform, the input current harmonics, and the power factor. This paper presents a quantitative analysis of single and three phase rectifier input current harmonics, total harmonic distortion, and power factor as a function of the output filter inductance under balanced and unbalanced conditions. Also, its performance under the supply voltage including harmonics be investigated. These results provide a reference for selecting reasonable rectifier's output filter inductance for given harmonics or power factor criterion.

• 전력전자학회논문지
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• 제3권2호
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• pp.148-155
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• 1998

역률개선을 위한 변압기 자기에너지 궤환 기법을 이용한 새로운 단일 전력단, 단일 스위치 방식의 AC/DC 컨버터를 제안한다. 제안한 컨버터의 동작원리 및 해석을 수행하였다. 제안한 컨버터는 선전류 고조파 왜곡이 작으며 고역률 및 정확한 전압 조정이 가능하다. 실험모델은 단일 역률에 가까운 역률을 보이며 IEC 555-2를 충분히 만족시킨다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.489-492
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• 2000

A novel low-cost simple and unity-power-factor electronic ballast is presented. The proposed electronic ballast employs a bypassing capacitor and load networks composed of ballast capacitors and small charge pump capacitors as power factor correction circuit combined with the secondary winding of the transformer in the self-excited current-fed push-pull resonant inverter(CF-PPRI) resulting in cost-effectiveness and higher efficiency. By analyzing the principles of power factor correction mathematically optimum design guidelines are presented. Since the lamps are used in power factor correction stage the input power is automatically adjusted according to the number of the lamps.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.490-491
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• 2008

A photovoltaic power generation system is one of the ideal clean energy sources increasingly replacing fossil fuel, which has many environmental problems such as exhausted gas or air pollution. As a photovoltaic generation system should meet the requirement to be connected to utility, power factor is an important factor for the high quality of power. This paper implements a power factor controller to improve the power quality of utility interactive photovoltaic system. To verify the effectiveness of the implemented power factor controller, the results by Electromagnetic Transients Program (EMTP) are presented.

• Journal of Information Technology Applications and Management
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• 제13권4호
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• pp.291-302
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• 2006

The current paper proposes fast distributed constrained power control (FDCPC) with a non stationary relaxation factor as the next power update for CDMA cellular power control systems. A review is also given of unconstrained control algorithms: distributed power control (DPC), unconstrained second order power control (USOPC), and DPC with a stationary relaxation factor (DPCSRF) To improve the performance of outage probability convergence, DCPC with a non stationary relaxation factor (FDCPC) is proposed. Under constrained conditions, the convergence rate of FDCPC is shown to outperform that of DCPC and constrained second order power control(CSOPC).

• Journal of Power Electronics
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• 제12권5호
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• pp.699-707
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• 2012

This paper proposes a single-stage half-bridge electronic ballast with a high power factor using only a single coupled inductor. Compared to conventional high power factor electronic ballasts, the proposed ballast is a simpler circuit with a low cost and a high reliability. The proposed ballast is made up of a power-factor-correction (PFC) circuit and a self-oscillating class-D inverter. The PFC and inverter stages of the proposed ballast are simplified by sharing only a single coupled inductor and two common switches. The proposed PFC circuit can achieve a high power factor and low voltage stresses of the switches. A saturable transformer in the self-oscillating class-D inverter determines the switching frequency of the ballast. Experimental results obtained on a 30W fluorescent lamp are discussed.

• 전력전자학회논문지
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• 제26권4호
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• pp.302-305
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• 2021

Selection of the optimal inductance for power factor improvement of a buck AC/DC light-emitting diode (LED) driver with wide input voltage range is described in this study. The power factor change based on the slope compensation is obtained for various normalized output current (NOC) values using discrete-time domain analysis. The possibility of implementing constant slope compensation is described using power factor curves for various NOC values. NOC = 0.5 is chosen for the value of inductance with consideration for the simple implementation and reduction of inductor size. Experimental results of the inductance corresponding to NOC = 0.5 are presented.