• 컴퓨터교육학회논문지
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• 제10권5호
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• pp.53-60
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• 2007

학습효율의 향상을 위해 본 논문에서는 웹기반 가상실험시스템과 원격실험시스템을 적절하게 통합하여 전기전자회로에 대한 하이브리드 실험시스템을 구현하였다. 먼저, 전기/전자회로 실험에 대한 웹기반 가상실험실을 개발하여 개념학습, 가상실험, 평가등의 3개의 주요 세션과 그에 대한 관리시스템으로 구성하였다. 다음으로 가상실험을 진행하는 동안 발생할 수 있는 현실감의 부족성 문제를 해결하기 위해 전기전자회로에 대한 원격실험시스템을 구현하였다. 제안된 가상/원격실험시스템은 독립적인 형태로 사용될 수도 있지만, 학습효율을 극대화하기 위해서 두 개의 시스템을 통합하여 하이브리드 전기전자 실험시스템을 구현하였다.

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.84-88
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• 2008

In this paper, we analyze the errors associated with electric field interference for fiber-optic voltage sensors working in a three-phase electric system. For many practical conductor arrangements, the electric filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of 1 %.

• 한국전기전자재료학회논문지
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• 제26권7호
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• pp.515-521
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• 2013

Magnetoelectric(ME) bulk composites with PZT-PNN-PZN/$Fe_2O_4$ were prepared by using a conventional ceramic methods and investigated on the ME voltage vs frequency of ac magnetic fields. We made the electric equivalent circuits by using the Maxwell-Wagner model and simulated the frequency dependence of ME voltage in low frequency region. ME devices were described by a series of two equivalent circuits of piezoelectric and magnetic, which have the relaxation time ${\tau}$ due to the interaction between ME device and load resistor. Equivalent circuit of piezoelectric material is independent of frequency. However ferrite magnetic materials have Debye absorption and dipolar dispersion, whose equivalent circuit is a function of frequency. Therefore we suggest the resistance in the equivalent circuit is proportion to $1+{\omega}^2{\tau}^2$ and the capacitance is in inverse proportion to $1+{\omega}^2{\tau}^2$ in the magnetic materials.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.261-266
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• 2018

When the clamp meter approaches the electric path where current is flowing, leakage current can be measured at a distance from the electric current because the induced current increases as the magnitude of the current increases and approaches nearer to the electric path. Therefore, measurements were carried out from a distance to avoid this effect. In addition, the measured values differ depending on the location of the power line that penetrates the ZCT of the clamp meter, thus measurements were performed at a location where this effect was minimized. The fraction of compliant branch circuits, whose leakage current was lower than 1.00 mA, was found to be 69.0% out of the total of 439 branch circuits, while the percentage of compliant branch circuits having an insulation resistance higher than $0.20M{\Omega}$ was found to be 93.2%. The reason why the percentage of compliant branch circuits with low leakage current was low might be due to the inclusion of capacitive leakage current in the total measured leakage current.

• Journal of the Optical Society of Korea
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• 제11권4호
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• pp.177-182
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• 2007

This paper discusses the errors associated with electric field cross talk for optical voltage sensors in a three-phase electric system and provides a solution to compensate the errors. For many practical conductor configurations, the electric field cross talk may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the cross talk and built an electronic circuits based on it. The mechanism of the compensation and the corresponding error reduction were discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1390-1393
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• 2002

Comparative analysis of driving inverters for piezo-electric transformer (PT) is performed and the suit- able drive circuit for portable devices such as personal digital assistants (PDA) is chosen with the experiment in this paper. As a result, a single-switch inverter with a small two winding reactor is chosen, and then the advantages of this method are clarified. It is also confirmed that the driving inverter with this method enables to realize a stabilized AC 400v output and 82% power efficiency from DC 3V input under the conditions of the variations of load current or input voltage from the experiments. Piezo-electric Transformer, Back-Light System, Single-Switch Driving Circuits, Control Method

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.468-468
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• 2000

In our laboratory, the control aspects are investigated in the photovoltaic power generation systems (PV systems). The PV system is very good for earth environment, but if it connects to power network system, many problems are raised (protection, voltage, harmonics etc.). In this paper, we present the result of the basic studies for the building of the PV system that amplifies the electric energy obtained from the solar cell. We consider electronic circuits in order to protect the PV system from power surge induced by lightning and also design an electronic circuit in order to detect defaults in the power network system. We would like to integrate these circuits into the PV system by considering its control equipment build by 8-bit microcomputer using various control theory (fuzzy, neural network etc.).

• Journal of Magnetics
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• 제12권4호
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• pp.156-160
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• 2007

In this paper, we analyze the errors associated with magnetic field interference for fiber-optic current sensors working in a three-phase electric system and provide a solution to compensate the interference. For many practical conductor arrangements, the magnetic filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of ${\pm}1%$.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.56-59
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• 2001

An effective method of detecting inter-turn short circuits on round rotor windings is described. Shorted-turns can have significant effects on a generator and its performance. A method of detecting inter-turn short circuits on rotor windings is described. The approach used is to measure the rate of change of the air-gap flux density wave when the rotor is at operating speed and excitation is applied to the field winding. The inter-turn short circuits sensor for synchronous generator's field winding has been developed. The sensor, installed in the generator air-gap, senses the slot leakage flux of field winding and produces a voltage waveform proportional to the rate of change of the flux. For identification of reliability for sensor, a inter-turn short circuits test was performed at the West-Inchon combined cycle power plant on gas turbine generator and steam turbine generator. This sensor will be used as a detecting of shorted-turn for field winding of synchronous generator. The purpose of this paper is to describe the design and operation of a sensitive inter-turn short circuits detector. In this paper, development of inter-turn short circuits sensor for field winding of synchronous generator and application in a field.

• 실천공학교육논문지
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• 제11권2호
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• pp.143-150
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• 2019

회로 이론은 전기 및 전자 공학 분야에서 가장 기본이 되는 다양한 회로의 해석과 설계를 체계화한 학문으로 회로 이론 교과목은 전기 및 전자 공학도라면 반드시 습득하도록 4년제 대학을 기준으로 학부 2학년에 한 학기 내지는 2 학기에 걸쳐 전공 교과목으로 편성되어 있다. 또한 학생들이 회로 이론에 대한 이해도를 높이고, 실제 회로를 구성한 실험을 통하여 회로 설계에 대한 기술 및 응용력을 습득할 수 있도록 하는 실험 교과목이 이론 교과목을 뒷받침하기 위해 동반 편성되고 있다. 본 논문에서는 회로 이론을 뒷받침하는 실험 교육에 대한 학습 효과를 높이기 위해 전기회로 설계 및 실험 교과목에서 시행하고 있는 수업 방법에 대한 사례 연구에 대해 기술한다. 이를 위해 이론 학습, 시뮬레이션, 실험 및 설계 프로젝트 등이 복합적으로 구성된 15주 수업 모형을 제안한다. 제시된 수업 모형에서는 이론을 보완하기 위한 시뮬레이션과 사전 실험 준비 과정이 강화되고, 공학 엔지니어로서의 실질적인 회로 설계 능력을 배양하기 위한 설계 프로젝트가 도입되어 운영된다. 5년 동안의 운영 결과는 제안된 모형이 효용성이 있음을 보여준다.