• 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.

• Journal of Power Electronics
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• 제12권6호
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• pp.954-959
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• 2012

A hybrid switch that uses a microelectromechanical system (MEMS) switch as a gate driver of a MOSFET is applied to an energy harvesting system. The power management circuit adopting the hybrid switch provides ultralow leakage, self-referencing, and high current handling capability. Measurements show that solar energy harvester circuit utilizing the MEMS-MOSFET hybrid switch accumulates energy and charges a battery or drive a resistive load without any constant power supply and reference voltage. The leakage current during energy accumulation is less than 10 pA. The power management circuit adopting the proposed hybrid switch is believed to be an ideal solution to self-powered wireless sensor nodes in smart grid systems.

• 상하수도학회지
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• 제24권6호
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• pp.683-690
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• 2010

Renewable and unutilized energy (biogas power generation, wind power, solar, small hydro-power, sewage heat source, etc.) seems to be suitable to install for the sewage treatment facilities. There are 357 sewage treatment plants in 2007. 17 plants among these have been operating for self-supporting energy by using solar power, small hydro-power and biogas in 2008. Newly built sewage treatment plant of 96,000 $m^3$/day for a newtown is expected to get up to energy consumption of 10 GWh/yr. If solar energy, small hydro-power and biogas-equipments were applied to the new treatment plant, self-supporting energy of the new sewage treatment plant will get up to 56.1%. As a results, about 2,379ton $CO_2$/yr $CO_2$ emission reduction can be expected by using renewable energy. These efforts for self-supporting energy will lead sewage treatment plant to new energy recycle center.

• 한국체육학회지인문사회과학편
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• 제54권3호
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• pp.231-242
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• 2015

이 연구는 운동선수의 자기관리와 자기성찰에 의한 감성지능을 검증하는 데 목적이 있다. 이러한 목적을 규명하기 위한 연구대상은 대학운동선수 총 200명을 무선으로 표본추출 하였다. 운동선수로 협회 등록이 되어있는 대학선수 중에서 서울지역 소재 K대학을 중심으로 최종 표집하였다. 자기관리는 허정훈(2001)이 사용한 선수자기관리 문항을, 자기성찰은 황주연(2011)이 검증한 문항을, 감성지능은 김성은(2010)이 사용한 감성지능을 사용하였다. 설문구성은 5점 리커트(Likert)척도이며, 신뢰도계수인 내적합치도는 .68~.85이다. 조사절차는 자기평가기입법으로 완성된 설문지를 상관분석과 다중회귀분석으로 검증한 결과, 첫째, 자기관리의 훈련관리는 자기탐색에, 대인관계관리와 몸관리는 타인이해에, 몸관리는 타인탐색에 정신력관리는 자기이해 등에 정적으로, 고유행동관리는 타인탐색에 부적으로 영향을 미치는 것으로 나타났다. 둘째, 자기관리의 정신력관리는 자기감성인식에, 정신력관리와 생활관리는 감성활용에, 정신력관리는 타인감성인식에, 정신력관리와 대인관계관리는 감성조절에 정적으로 유의한 영향을 미치는 것으로 타나났다.

• Journal of Power Electronics
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• 제16권1호
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• pp.121-132
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• 2016

In this paper, high-efficiency design methodology of a zero-voltage-switching full-bridge (ZVS-FB) pulse width modulation (PWM) converter for server-computer power supply is discussed based on self-driven synchronous rectifier (SR) performance. The design approach focuses on rectifier conduction loss on the secondary side because of high output current application. Various-number parallel-connected SRs are evaluated to reduce high conduction loss. For this approach, the reliability of gate control signals produced from a self-driver is analyzed in detail to determine whether the converter achieves high efficiency. A laboratory prototype that operates at 80 kHz and rated 1 kW/12 V is built for various-number parallel combination of SRs to verify the proposed theoretical analysis and evaluations. Measurement results show that the best efficiency of the converter is 95.16%.

• 재활간호학회지
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• 제3권2호
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• pp.196-211
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• 2000

The purpose of this study was to determine the effects of 5 weeks self-help management program on reducing depression, promoting Activity of Daily Livings(ADLs), Instrumental Activity of Daily Livings(IADLs), grasping power, hope and self-efficacy for post stroke patients visiting public health care centers in Seoul. This was pre-experimental study, and the subjects were 27 post stroke hemiplegic patients. The program was composed of five sessions and each session had health education on stroke, ROM exercise and recreation. Data were collected from May to November, 2000, and all subjects were asked to complete the Questionnaires, be measured vital signs and grasping power. Data were analyzed with frequency, percent, paired t-test, and Pearson's correlation coefficient using SAS(version 6.12) program. The results were as follows : 1) The scores of ADLs were increased from 27.04 to 28.22 after program, and that was statistically significant(p=.005). 2) The scores of IADLs were increased from 18.70 to 19.78 after program, and that was statistically significant(p=.004). 3) The grasping power of right hand were increased from 21.87kg to 26.93kg after program, and that was statistically significant(p=.002). But the grasping power of left hand were statistically insignificant(p=.919). 4) The scores of depression were decreased from 39.63 to 35.30 after program, and that was statistically significant(p=.030). 5) The scores of hope were increased from 30.89 to 34.15 after program, and that was statistically significant(p=.002). 6) The scores of self-efficacy were increased from 67.70 to 76.37 after program, and that was statistically significant(p=.000). According to the results of this study, the scores of Activity of Daily Livings(ADLs), Instrumental Activity of Daily Livings (IADLs), hope, and self-efficacy and the grasping power were improved and depression was reduced in post stroke patients participating in self-help management program. Therefore we recommend to use self-help management programs as a nursing intervention for the post stroke patient.

• Journal of Power Electronics
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• 제10권4호
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• pp.444-449
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• 2010

The generation of electric power using self excited induction generation (SEIG) is a viable option in remote and rural areas where grid electricity is not available. The generated voltage and frequency of these machines, however, varies with varying loads. This characteristic can be resolved either by adjusting the values of the excitation capacitance or by controlling the prime mover speed. Further, in a single-point constant power application, where the machines deliver a fixed amount of power, the electronic load controller (ELC) can be used to switch-in or switch-out a dump load whenever the consumer load decreases or increases respectively. This paper presents a detailed analysis and the design of a microcontroller based SEIG -ELC system intended for stand-alone pico hydro power generation. The simulated performance of the controller is supplemented by experimental results.

• Journal of Power Electronics
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• 제18권4호
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• pp.1099-1110
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• 2018

In this paper, a loss minimization control method for interior permanent magnet synchronous motors is presented with considering self-saturation and cross saturation. According to variation of the d-axis and q-axis inductances by different values of the d-axis and q-axis components of currents, it is necessary to consider self-saturation and cross saturation in the loss minimization control method. In addition, the iron loss resistance variation due to frequency variation is considered in the condition of loss minimization. Furthermore, the loss minimization control method is compared with maximum torque per ampere (MTPA), unity power factor (UPF) and $i_d=0$ control methods. Experimental results verify the performance and proper dynamic response of the loss minimization control method with considering self-saturation and cross saturation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.427-428
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• 2008

We have studied design and application about an self generation equipment for underground power transmission cable. The split CT(Current Transformer), which has the applicable underground power transmission cable, was manufactured through electromagnetic simulation of magnetic core. And manufactured the AC-DC converter that supplied stable DC power for PLC modem when current of power line has more than 150A. An self generation equipment using the CT and AC-DC converter get into operation the PLC modem consistently. As a result, the underground power transmission cable was showed the application possibility through the stable communication and network characteristics.

• 동력기계공학회지
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• 제3권4호
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• pp.69-78
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• 1999

In the single-input and single-output system, the parameter of plant is scalar polynomial, but in the multiple input and multiple output, it accompanies, being matrix polynomial, the consideration of observable controlability index or problems non-commutation in matrix polynomial as well as degree, and it is more complex to deal with. Therefore, it is thought that a full research on the single-input and single-output system is not sufficient. This paper proposes that problems of minimum variance self-tuning regulator by using numerical calculation example of multivariable system and pole assignment self-tuning regulator.