• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1265-1267
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• 1994

EPDM has excellent electric characteristics and so that it has been rapidly finding use is high voltage applications in recent years. At present EPDM is widely used for insulator of cable and accessories, and further the commercial use of Premolded housing for elbow surge arrester is started. In this paper, we have measured the temperature, pressure and voltages dependence of $tan{\delta}$ in EPDM. As a results, dielectric characteristics($tan{\delta}$) increases slightly with increasing the temperature. However, it is almost independent of the pressure and voltages.

• 한국인쇄학회지
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• 제23권2호
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• pp.15-23
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• 2005

This analog communication system overcomes a limit of the digital communication that used an electric power line, and shows a strong characteristic by decrease of impedance along a load or surge-voltage and the same noise. this system is to detect an sound signal added to light through an photo-sensor and a filter circuit. And a signal detected in this way is transmitted to sound through a speaker of an earphone again.

• 조명전기설비학회논문지
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• 제28권11호
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• pp.100-105
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• 2014

In this paper, Uninterruptible Power Supply(UPS) Inverter system using Carrier Frequency Modulated PWM (CFM-PWM) is proposed to reduced harmonics and electromagnetic noise. Power conversion of UPS system is executed by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI which deteriorate the reliability of the UPS system. This Problems improved by Random PWM switching method. The simulation results of the proposed system was compared with the system using conventional method using Matlab/Simulink. The results show that the output voltage and current harmonics of the proposed UPS system significantly decreased and spread into wide band area by the proposed Carrier Frequency Modulated PWM(CFM-PWM) method based on the Space Vector Modulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.585-587
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• 1998

In 22.9 kV-Y distribution lines, Several kinds of over-voltages occur. These over-voltages are usually surge types except controling the bus voltages for line voltage drop. The measuring over-voltages in 22.9 kV lines is a very difficulty skill. This paper introduces the study on the measurement system of over-voltages in 22.9kV distribution lines. It has been researching in KEPCO since 1995.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.194-195
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• 2006

This study evaluated the impedance characteristics of earth termination system and developed a variable frequency-typed inverter (measuring tool) for the utilization in ground design for lightning protection. The variable-frequency-typed inverter were composed of rectification part, voltage adjuster, IGBT controller and measuring part. Meanwhile, the square wave signal of variable frequency converted its frequency up to lightning surge band by using an IGBT after rectifying an alternating current (AC). It conducted performance evaluation of ground impedance of actual earth termination system by using the developed measuring tool for ground impedance and confirmed that such impedance-oriented performance evaluation was effective in the design of lightning protection.

• 산업경영시스템학회지
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• 제24권67호
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• pp.69-76
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• 2001

In order to review the failure rate of PC monitor under normal environmental conditions, we experimented for various levels of each factors, e.g. Power on/off, DPM mode, using voltage incoming Surge, Torque strength etc. According to the results of experiment and SN ratios we investigated that the causes of the failure for the horizontal output TR of monitor are Mode change, dispersion of Torque and $h_{FE}$ and these are critical effect. For the new reliability test we suggested that strengthened part tests in IQC branch, Torque change controls in the TR specification are necessary.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.519-522
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• 2003

'KRS 6330-3256라' standard regulates performance test of insulating transformer for protecting the electronic interlock linkage equipment which is being done by test procedures and methods according to the standard. The balance/unbalance test evaluating the performance of transformer are applied by impulse voltage($l2/200{\mu}s$) but affected by many other factors. Therefore, the review about these is necessary to have the reliability and reappearance of test results. In this paper, we have simulated about several phenomenon appearing in real balance/unbalance test and compared simulated results with real ones. With the basis of these results, the influence to test result of inner and outer factors are investigated and analyzed and established the plan boosting the reliability and reappearance of test results.

• 대한전기학회논문지
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• 제34권4호
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• pp.135-143
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• 1985

The failure and erosion of relay contacts mainly depend on the presence of particles deposited on the contact surface in various contaminated atmospheres. In this paper, the effects of sea water and circuit parameters on the arcing and quenching of magnet relay contacts are studied. The sea water pollutants of relay contact surface have led to increase the arcing numbers on making contact, and the mean arc durations on breaking contacts. Moreover, the maximum surge voltage and mean arc duration between relay contacts are also varied significantly by the circuit parameters. The effects of the spark quenching circuits using condenser of diode on the arcing of contacts are also discussed.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.93-101
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• 2002

In this study, the stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the C-Class(200$\^{C}$ ) insulation system of traction motors. The complex accelerative degradation was periodically performed during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, the condition diagnosis test such as insulation resistance '||'&'||' polarization index, capacitance '||'&'||' dielectric loss and partial discharge properties were investigated in the temperature range of 20 ∼ 160$\^{C}$. Relationship among condition diagnosis tests was analyzed to find a dominative degradation factor and an insulation state at end-life point.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기설비전문위원
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• pp.52-54
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• 2007

최근 정보통신의 발달과 함께 고정밀의 전기기기류가 급증하고 있으며, 이들의 회로에는 반도체를 포함하는 전자회로가 주로 사용되고 있어 고전압 및 대전류에 의한 서지로부터 취약성을 드러내고 있다. 따라서 전기적인 외력으로 부터 이들을 안전하게 보호하기위해 서지보호 장치가 널리 사용되고 있다. 그러나 이들 보호 장치를 사용함에도 불구하고 누전차단기의 오동작을 유발하여 정전 등으로 인한 파급사고가 발생할 뿐만 아니라 경제적인 손실과 같은 문제점을 초래하고 있다. 본 연구에서는 서지 전압에 대한 누전차단기의 오동작 특성을 조사하기 위해 IEC C62.41의 규격에 따라 $1.2/50{\mu}s$ 서지발생기를 제작하여 상용주파 전원이 인가 된, 무부하 상태의 누전차단기에 서지를 발생시켜 누전 차단기의 오동작 여부를 측정하였다. 그 결과 시험에 사용된 상용 누전차단기 모두는 오동작을 하여 이에 대한 원인 규명과 더불어 개발에 시급함을 제시하고자 하였다.