• International journal of advanced smart convergence
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• 제10권4호
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• pp.158-164
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• 2021

The purpose of this study is to analyze the structural relationship between customer's pleasure, customer satisfaction, switching cost, and relationship commitment using the fitness center and provide implications. Specifically, this study aims to investigate the effect of the degree of customer's awareness of pleasure on the relationship commitment through the medium of customer satisfaction and switching cost. For this purpose, the structural equation model was constructed based on the previous studies, and the exogenous variables were pleasure, and the endogenous variables were customer satisfaction, switching costs and relationship commitment. The subjects of this study were customers who used fitness centers in the metropolitan area. The sampling method for the sample survey was a total of 277 people using convenience sampling. 257 copies were used as final data except for 20 samples that were not appropriate for the study. The statistical program for data analysis was IBM SPSS Ver. 26.0 and Amos 21.0. The specific data processing method is as follows: First, frequency analysis was conducted to understand the general characteristics of the subjects. In order to verify the validity and reliability of the research tools, confirmatory factor analysis and reliability analysis were conducted. In order to understand the theoretical relationship between each variable, structural equation model was conducted. The results of data processing on the research model are as follows: First, the pleasure of the fitness center customers had a positive effect on customer satisfaction. Second, customer satisfaction had a positive effect on the switching costs. Third, customer satisfaction had a positive effect on the customer commitment. Fourth, switching costs had a positive effect on customer commitment.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1492-1497
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• 1999

High impedance fault(HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equipment damage or personal threat. This paper proposes the model of the high impedance fault in transmission line using the ZnO arrester and resistance to be implemented within EMTP. The performance of the proposed model is tested on a typical 154[kV] korean transmission line system under various fault conditions. Wavelet transform is efficient and useful for the detection of high impedance fault in power system, because it uses variable windows according to frequency. In this paper, HIF detection method using wavelet transform can distinguish HIF form similar fault like arcfurance load, capacitor bank switching and line switching.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.224-227
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• 2004

The goal of this paper is optimal switching angle of switched reluctance motor drive system for maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed. As results, it improved the efficiency about $2[\%]$. And a torque ripple is also sufficiently reduced compared with that of the conventional switching angle magnetizing approach. In order to start softly regardless of a large ripple torque, the profile of phase current is predicted by the ANFIS, and current control mode was adapted when it is operated under the starting speed. Variable implementations on the fields will guarantee the more practical drive system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권10호
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• pp.625-633
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• 2004

This paper proposed a boost input type single stage resonant power supply for driving magnetron device. The proposed power supply can control both input power factor and output power at the same time. Also, because ZVS is achieved using the resonance between leakage inductance and resonant capacitance, switching losses are drastically reduced. To prevent breakdown or moding phenomenon of the magnetron due to excessive starting voltage, variable frequency ignition method is also proposed. Experimental results for the prototype power supply are presented and discussed to verify the validity of the proposed power supply.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1373-1375
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• 1999

High impedance fault (HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equiment damage or personal threat. This paper proposes the model of HIF in transmission line using the ZnO arrester and resistance to be implemented within EMTP. Wavelet transform is efficient and useful for the detection of HIF in power system, because it uses variable windows according to frequency. HIF detection method using wavelet transform can distinguish HIF from similar phenomena like arcfurance load, capacitor bank switching and line switching.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.319-323
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• 1990

VSS controller is suited for systems where the robust performances in the presence of parameter variations and disturbances are most important. The practical realization of such robust VSS algorithm using DSP ($TMS_{32020}$) is dicussed in this paper. PWH-like control signal which is produced by directly using VSS control algorithm substitutes the PWM amplifier. And the armature current is used in construction of switching function for the purpose of increasing switching frequency. In order to compensate steady state error produced by various external disturbances practical integral compensator is considered.

• 전기전자학회논문지
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• 제14권2호
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• pp.9-15
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• 2010

In this study, we have been proposed the new type of a transcranial magnetic stimulation adopted a variable voltage capacitor with Cockcroft-Walton circuit and constant-frequency current resonant half-bridge inverter. This a transcranial magnetic stimulation has some merits compared with the conventional one. First, it doesn't require the high voltage transformer. And second, it has less switching losses, compact size and capability in adjusting the transcranial magnetic stimulation output energy precisely. In this paper, we have performed the output characteristics of a transcranial magnetic stimulation system which is well known as magnetic stimulation. The tested results are described as a function of pulse repetition rate and switching numbers of the half-bridge inverter.

• 한국통신학회논문지
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• 제42권4호
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• pp.864-870
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• 2017

본 논문은 넓은 부하 전류를 요구하는 휴대 기기에서 사용될 목적으로 주파수 전압 변환을 이용하여 모드 제어 가능한 듀얼 모드 벅 변환기를 설명한다. 기존의 히스테스테릭 벅 변환기의 문제인 저 부하에서의 PLL 보상 및 효율 저하를 제안하는 듀얼 벅 변환기의 개선된 PFM 모드를 통해 해결한다. 또한 기존의 듀얼 모드 벅 변환기의 주요 회로인 모드 제어기에서의 부하 변화 감지의 어려움과 느린 모드 전환 속도를 제안하는 모드 제어기로 개선 시킨다. 제안하는 모드 제어기는 최소 1.5us의 모드 전환 시간을 가진다. 제안하는 DC-DC 벅 변환기는 $0.18{\mu}m$ CMOS 공정에서 설계하였으며 칩 면적은 $1.38mm{\times}1.37mm$이다. 기생 소자를 포함한 인덕터와 커패시터를 고려한 후 모의실험 결과는 1~500mA의 부하 전류 범위에서 입력 전압을 2.7~3.3V를 가지며 PFM 모드는 65mV이내, 히스테리틱 모드에서는 고정된 스위칭 주파수 상태에서 16mV의 출력 리플 전압을 가지는 1.2V의 출력 전압을 생성한다. 제안하는 듀얼 모드 벅 변환기의 최대 효율은 80mA에서 95%를 나타내며 해당 전체 부하 범위에서 85% 이상의 효율을 지닌다.

• Journal of Power Electronics
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• 제14권2호
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• pp.271-281
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• 2014

Fluctuating wind conditions necessitate the use of a variable speed wind turbine (VSWT) with a AC/DC/AC converter scheme in order to harvest the maximum power from the wind and to decouple the synchronous generator voltage and frequency from the grid voltage and frequency. In this paper, a combination of a three phase diode bridge rectifier (DBR) and a modified topology of the diode clamped multilevel inverter (DCMLI) has been considered as an AC/DC/AC converter. A control strategy has been proposed for the DCMLI to achieve the objective of grid interface of a wind power system together with local load compensation. A novel fixed frequency current control method is proposed for the DCMLI based on the level shifted multi carrier PWM for achieving the required control objectives with equal and uniform switching frequency operation for better control and thermal management with the modified DCMLI. The condition of the controller gain is derived to ensure the operation of the DCMLI at the fixed frequency of the carrier. The converter current injected into the distribution grid is controlled in accordance with the wind power availability. In addition, load compensation is performed as an added facility in order to free the source currents being fed from the grid of harmonic distortion, unbalance and a low power factor even though the load may be unbalanced, non-linear and of a poor power factor. The results are validated using PSCAD/EMTDC simulation studies.

• 조명전기설비학회논문지
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• 제13권3호
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• pp.124-128
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• 1999

본 연구는 고주파 직렬공진 인버어터를 이용한 20[kHz],10[kHz]급 고효율 유도가열장치에 관한 것이다. 치가열체인 부하변동에 대해서는 인버어터의 직류 입력 전압을 가변시키고 인버어터 스윗칭을 공진 주파수를 추종해 동작시킴으로써 무료전력을 최소화 할 수 있는 회로 구성을 제시하였다. 그리고 시뮬레이션과 실험을 통해 유도가열장치의 인버어터 역률이 약0.96으로 양호함을 알 수 있었다.