• 한국산학기술학회논문지
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• 제10권3호
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• pp.470-475
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• 2009

본 연구에서는 핀-관 열교환기와 PF 열교환기의 열전달 특성과 이를 적용한 공조기의 성능을 비교 조사하였다. 또한 공조기의 냉방기간 에너지효율(CSPF)을 평가하였다. 열교환기 실험을 위해 3종류의 열교환기에 대한 열전달 및 압력강하를 그리고 공조기 성능평가를 위해 냉방표준, 냉방저온에서 냉방능력, 소비전력, COP를 산출하였다. 실험은 칼로리미터와 항온수조를 사용하여 수행되었다. 유입공기 속도가 증가함에 따라 열교환기의 열전달율과 압력강하는 증가하였다. PF 열교환기 적용 시스템의 적정 냉매량은 핀-관공조기보다 약 $15{\sim}20%$ 감소하였으나, 냉방능력은 증가, 소비전력은 감소하여 COP는 향상되었다. 사각형 핀을 가진 PF 열교환기가 삼각형 핀보다 냉방능력과 COP가 더 우수하였다. 실환경 온도조건을 반영하기 위해 PF 열교환기와 핀-관 열교환기 적용 시스템의 CSPF가 계산되었다.

• 전력전자학회논문지
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• 제18권4호
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• pp.397-402
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• 2013

This paper proposes a new passive type LED driver which satisfies the standard of power factor (PF) and total harmonic distortion (THD). The proposed passive LED driver also has high-efficiency and long-life time characteristics compared to active LED driver which is composed of op-amp, switches and so on. By using just passive components such as inductor, capacitor, and diode, it has resolved extremely short-life time and low-efficiency problems of previous LED drivers. It has achieved PF of 0.99, THD of 16.4 %, and the total efficiency of 95 %. The proposed passive LED driver is fully analyzed and verified by simulations and experiments, which results are in good agreement each other.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.266-269
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• 1999

Several power factor correction(PFC) circuits are presented to achieve high PF electronic ballast for both voltage-fed and current-fed electronic ballast. The proposed PFC circuits use valley-fill(VF) type DC-link stages modified from the conventional VF circuit to adopt the charge pumping method for PFC operations during the valley intervals. In voltage-fed ballast, charge pump capacitors are connected with the resonant capacitors. In current-fed type, the charge pump capacitors are connected with the additional secondary-side of the power transformer. The measured PF and THD are higher than 0.99 and 15% for all proposed PFC circuits. The lamp current CF is also acceptable in the proposed circuits. The proposed circuit is suitable for implementing cost-effective electronic ballast.

• Journal of Power Electronics
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• 제14권2호
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• pp.257-264
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• 2014

A novel converter-free AC LED driver that is highly resistant to the fluctuation of AC voltage is proposed in this study. By removing large passive components, such as the bulky capacitor and the large-value inductor, the integration of the driver circuit is enhanced while the driving current remains stable. The proposed circuit provides LED lamps with a driving current that can follow the sinusoid waveform to obtain a very high power factor (PF) and low total harmonic distortion (THD). The LED input current produced by this driving current is insensitive to fluctuations in the AC voltage. Users will thus not feel that LED lamps are flashing during the fluctuation. Experiment results indicate that the proposed system can obtain PF of 0.999 and THD as low as 3.3% for a five-string 6 W LED load under 220 V at 50 Hz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.284-286
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• 2004

When Power market is restructured, we have an argument with selecting Transmission loss factors. First, we determine the method of calculating Transmission loss factor using OPF (Optimal Power Flow) or PF (Power Flow Equation). Then, we decide that we applicate the factor which are identical value all the year or which are floating Transmission loss factor every each hour. In this study, we accomplish the method of computing Transmission cost in competitive market.

• Journal of Power Electronics
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• 제15권3호
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• pp.644-651
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• 2015

This paper introduces a novel digital one cycle control (DOCC) boost power factor correction (PFC) converter. The proposed PFC converter realizes the FPGA-based DOCC control approach for single-phase PFC rectifiers without input voltage sensing or a complicated two-loop compensation design. It can also achieve a high power factor and the operation of low harmonic input current ingredients over universal loads in continuous conduction mode. The trailing triangle modulation adopted in this approach makes the acquisition of the average input current an easy process. The controller implementation is based on a boost topology power circuit with low speed, low-resolution A/D converters, and economical FPGA development board. Experimental results demonstrate that the proposed PFC rectifier can obtain a PF value of up to 0.999 and a minimum THD of at least 1.9% using a 120W prototype.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.123-127
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• 2001

In this paper, prototype high-power-factor single-stage electronic ballast for fluorescent lamps is designed and implemented. A new low cost single stage high power factor electronic ballast for fluorescent lamps is based on integration of two-boost converter and LC type high frequency resonant converter. A ballast is obtained by simple construction, because full bridge rectifier diode is eliminated and simple control circuit is applied. Using two boost converter operating positive and negative half cycle respectively at line frequency (60Hz), operation in discontinuous conduction mode performs high power factor. The experimental results Show the good performance as PF 0.99, $A_{THD}$ 15.4%, and CF 1.65 at Output 63.5W.W.

• 전기화학회지
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• 제20권3호
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• pp.55-59
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• 2017

본 연구에서는 밀도범함수법 (DFT; Density Functional Theory) 기반의 제일원리 계산을 통해 페로브스카이트 $La_{0.5}Ca_{0.5}MnO_3$ (LCMO) 재료의 열전 특성에 미치는 열처리 효과를 조사하고 실험을 통해 확인해 보았다. 시뮬레이션을 통해 얻어진 열전 파워팩터 (PF; Power Factor) 값은 열처리 온도가 올라감에 따라 증가하는 현상을 보였으며, 1100 K에서 높은 PF 값 ($S^2{\sigma}=566{\mu}W/m{\cdot}K^2$)을 나타내었다. 해당 PF 열전 특성 값은 전기전도도 (Electrical Conductivity) 값의 향상보다는 지벡계수 (Seebeck Coefficient)의 향상에 더욱 우세한 영향을 받은 것으로 확인되었으며, 실험을 통해 각각의 열전 특성들에 미치는 영향성을 확인하였다. 수열합성법을 통해 합성된 $La_{0.5}Ca_{0.5}MnO_3$ 재료를 가지고 600K ~ 1100K의 온도 조건에서 열처리 공정을 진행했으며, 이후 XRD (X-ray Diffraction) 분석과 SEM (Scanning Electron Microscope) 분석을 통해 재료의 특성을 분석하였다. 결과적으로 사방정계 구조를 가지는 페로브스카이트 LCMO 재료는 900K 이상에서 16~19 nm의 작은 결정 크기를 가지고 있음을 확인했으며, 이를 통해 열처리 온도의 증가가 열전 주요 특성인 전기전도도와 지벡계수 값을 각각 향상시킬 수 있음을 밝혔다.

• Journal of Power Electronics
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• 제16권1호
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• pp.190-204
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• 2016

An active front end (AFE) is required for a three-phase induction motor (IM) fed by a voltage source inverter (VSI), because of the increasing need to derive quality current from the utility end without sacrificing the power factor (PF). This study investigates a proportional-plus-integral (PI) controller based AFE topology that uses a super-lift converter (SLC). The significance of the proposed SLC, which converts rectified AC supply to geometrically proceed ripple-free DC supply, is explained. Variations in several power quality parameters in the intended IM drive for 0% and 100% loading conditions are demonstrated. A simulation is conducted by using MATLAB/Simulink software, and a prototype is built with a field programmable gate array (FPGA) Spartan-6 processor. Simulation results are correlated with the experimental results obtained from a 0.5 HP IM drive prototype with speed feedback and a voltage/frequency (V/f) control strategy. The proposed AFE topology using SLC is suitable for three-phase IM drives, considering the supply end PF, the DC-link voltage and current, the total harmonic distortion (THD) in supply current, and the speed response of IM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2562-2564
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• 1999

We have development the electronic ballast for metal halide discharge (MHD) lamp. The ballast consists of the boost pre-converter for power factor correction (PFC), a flyback a converter, half-bridge inverter and ignitor. To reject acoustic resonance phenomena, we have designed electronic ballast driving with the low frequency square wave. As results of this study, the ballast had not flicker phenomena and promoted corrected the factor (PF) highly