• 한국공작기계학회논문집
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• 제13권2호
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• pp.69-74
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• 2004

In general the surge pressure generated in hydraulic systems causes noise, vibration and odd effect to the system. To reduce the surge pressure, high frequency PWM control of 20KHz was attempted. To estimate the braking noise caused by surge, a vehicle equipped with on-board ABS hydraulic modulator has been experimented with respect to the various breaking condition. Thorough this experiments, it was found that breaking noise has been reduced using high frequency PWM control method compare with low frequency method. To evaluate high frequency control m practice, including verification of general functionality, EMI tests was experimented. Its was found that it is necessary to have the solution to electromagnetic interference(EMI) generated by switching elements.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.503-505
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• 1995

The surge arrester plays a vital role in the protection of substation against transient overvoltages resulting from lightning surges and system switching operations. The proper selection and application of the surge arrester is an integral part of the process of substation equipment insulation level selection. The paper outlines the basic consideration in modeling the lightning stroke, the surge arrester, and the system to be protected. The paper discusses the results of various cases simulated using the alternative transient computer program to evaluate the separation effects.

• 조명전기설비학회논문지
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• 제29권2호
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• pp.47-53
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• 2015

The study concerning about the grid connection of the large-capacity energy storage system(ESS) is increasing. However, the transient study such as lightning or switching surge necessarily occurred at power system with ESS has been hardly performed. Therefore, this paper performs the analysis of lightning surge in distribution system with ESS using electromagnetic transient program(EMTP). The battery model in Matlab/Simulink is modeled by EMTP, which is the specialized software for power system transient study. Also, the bi-directional power electronics for interconnection of the battery and distribution system are modeled by EMTP. When the lightning is occurred at interconnection point of ESS, this paper simulates the existence of ESS and operation conditions of ESS and analyzes the surge in distribution system and ESS according to the various conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1698-1699
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• 2007

This paper deals with the surge measurement system for low voltage power line of industrial plants. It consists of a capacitive divider, A/D conversion part, signal processing and control part. A FPGA and a DSP board were designed to fast signal processing and control. Also, in order to measure lightning surge and switching surge for a long time, data backup device was applied by using SD memory. A performance of the measurement system was verified through evaluation test using impulse calibration generator.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.21-26
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• 2018

In this paper, the switching characteristics of the active clamp type flyback converter, which is deemed suitable for the miniaturization of the external power supply for home appliance, were analyzed and the process of reducing the switching loss was explained. The active clamp type flyback converter operating in the DCM has confirmed that the surge voltage of the main switch does not occur and the turn-off / on loss of the switch do not occur in principle. Also, in the case of the switch for synchronous rectifier, it was showed that the switch current showed half-wave rectified sinusoidal characteristic, and the switching loss was reduced. The switching characteristics of the experimental results gathered from 120 W class prototype were compared with the theoretical waveform in the steady-state and it was confirmed that the power conversion efficiency of the active clamp type flyback converter was maintained high due to the reduction of the switching loss.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1675-1677
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• 1998

It is currently increasing to use surge protection devices in the protection of various electronic circuits from the transient overvoltages such as lightning strikes and switching surges. For this reason, the simulation methods, which can easily predict the protection performance of the devices, are strongly required in order to design the adequate surge protection circuits in lightning surge cut-off performance and economic aspects. This paper deals with ZnO varistor modeling method for designing a surge protection circuit and suggests the Pspice simulation model which takes the characteristic of varying clamping voltage into consideration during the time-to-crest, in range of $8{\sim}30{\mu}s$, of surge current applied to a ZnO varistor. The ZnO varistor Pspice simulation data introduced in this paper has produced almost same values as the measured results experimentally.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.111-117
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• 2008

일반적으로 산업현장에서 널리 사용되는 유도전동기는 상용인버터를 이용하여 속도제어를 하게 된다. 상용인버터로 구동되는 유도전동기는 인버터의 고속 스위칭에 의한 마이크로 서지전압을 발생한다. 이러한 마이크로 서지는 전동기의 소손뿐 만아니라 PLC 제어계통에 있어서 노이즈 문제를 발생하며, 생산 활동에 막대한 지장을 초래하게 된다. 본 논문에서는 마이크로 서지의 발생 메커니즘을 살펴본 후 전동기 소손 방지를 위한 대책을 제시하고 인버터 출력단에 LCR 필터를 부착하여 실험하였으며 결과로 마이크로 서지전압이 저감됨을 확인하였다 또한 PLC 제어계통의 노이즈 억제에 대해 이론적 고찰을 통해 대책도 제시하였다.

• 대한전기학회논문지:전력기술부문A
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• 제53권1호
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• pp.31-37
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• 2004

In this paper, the analysis result of the switching surge in substation including GIS(Gas Insulated Switchgear) has been described using the EMTP(Electro Magnetic Transient Program) program. After performing the modeling of the input data, we have reviewed the energization overvoltages of GCB(Gas Circuit Breaker) without closing resistor in 345kV network, according to the conditions of simultaneously operating switch and statistically operating switch. Firstly, it can be known that the energization overvoltage of single line is higher than that of parallel energized line. Secondly, the maximum energization overvoltage obtained in statistics switch is higher than one in simultaneous switch. From these results, it can be known that the phase-to-earth energization overvoltages of $\alpha$-$\beta$ section are less than 2.2 p.u when closing resistor is eliminated. Therefore, it is possible to consider the circuit breaker eliminated the closing resistor in $\alpha$-$\beta$ section.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.399-403
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• 2005

In this paper, we analyze on the effect of RC filter to mitigate transient overvoltage on the high voltage induction motor fed by H-bridge cascaded 7-level inverter. The switching surge voltage becomes the major cause to occur the insulation failure by serious voltage stress in the stator winding of high voltage induction motor. The effect of switching surge appears more serious in high voltage induction motor than low voltage induction motor. Consequently, we demonstrated that the RC filter connected to the motor terminals greatly reduces the transient voltage stress md ringing. The results of simulation show the suppression of transient overvoltage at the motor end of a long cable. using EMTP

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1001-1003
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• 1993

Steep-fronted surges associated with motor witching cause relatively large turn-to-turn winding stress. In order to calculate the surge level at the motor terminals, equivalent circuits consist of three parts with power sources, load cable and motor constants. This paper presents switching surges phenomena occurred in a high voltgae induction motor witching by EMTP.