• 한국환경과학회지
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• 제23권3호
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• pp.459-472
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• 2014

Storm surge height in the coastal area of Jeju Island was examined using the Princeton Ocean Model(POM) with a sigma coordinate system. Amongst the typhoons that had affected to Jeju Island for six years(1987 to 2003), the eight typhoons(Maemi, Rusa, Prapiroon, Olga, Yanni, Janis, Gladys and Thelma) were found to bring relatively huge damage. The storm surge height of these typhoons simulated in Jeju harbour and Seogwipo harbour corresponded relatively well with the observed value. The occurrence time of the storm surge height was different, but mostly, it was a little later than the observed time. Jeju harbour showed a higher storm surge height than Seogwipo harbour, and the storm surge height didn't exceed 1m in both of Jeju harbour and Seogwipo harbour. Maemi out of the eight typhoons showed the maximum storm surge height(77.97 cm) in Jeju harbour, and Janis showed the lowest storm surge height(5.3 cm) in Seogwipo harbour.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권12호
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• pp.616-619
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• 2004

Electrical circuits with semiconductor are very weak against lightning surge. The surge protective devices for electronic circuit and AC power lines are becoming more widely used. To achieve effective method of surge protection, there are needs for correlation between lightning surge and indoor wire length or installation height of indoor wire. The aim of this present work is to investigate the propagation characteristics of lightning surge according to variation of wire length. As a consequence, the maximum voltage at the end of the open wire in proportion to length of indoor wire. Therefore this result may be raw data for establishment of surge protection system.

• 조명전기설비학회논문지
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• 제26권8호
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• pp.96-101
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• 2012

A surge protection device of the metal oxide varistor(MOV) has been commonly used for preventing electrical damage in many electronic equipments. The MOV has a property that leakage current is increased and might be permanently damaged when it is exposed continuously to the electrical stresses such as lightening surges. In this paper, we propose a novel surge protection circuit adopting a silicon controlled rectifier(SCR) in the traditional protection circuits using the MOV device simultaneously. When lightning surges are injected to the proposed circuit, the MOV lets the surge pulses bypassing through the ground at first up to the level that SCR begins to operate. Above the threshold level of turning on the SCR, the SCR operates bypasses large surge currents to the ground. Proposed circuit was verified with a leakage current experiment and PSpice circuit simulations under the repeated surge injection environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1882-1884
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• 1996

This paper deals with the lightning surge counter. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. For the purpose of observing the occurrence frequency as a parameter of the amplitude of surge, two type surge counters were designed and fabricated. One is operated by surge currents, and the other is operated by surge voltages. The former consists of current sensor, metal oxide varister (MOV), rectifier, capacitor and electromagnetic counter. The latter consists of rectifier, voltage divider, comparator, photo coupler and counter circuit, and is useful for detecting the surge voltages.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.289-292
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• 2008

This paper describes the electrical characteristics of the ZnO surge arrester according to the variation of surrounding conditions. To investigate the characteristics of degraded ZnO surge arrester, 8/20 [${\mu$s], 2.5 [kA] impulse currents were applied to the ZnO surge arrester to be test. To present the effect of the surrounding con야tions, the leakage currents of ZnO surge arrester were measured to the surrounding temperature and wet conditions. As a result, the increase of ambient temperature causes the increase of resistive leakage current of ZnO surge arrester. Also, in the wet test, the outside leakage current through the ZnO surge arrester housing is much larger than the intrinsic leakage current.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1892-1896
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• 2008

Inverter-fed induction motors (IFM) are prevalent in traction vehicles. However, the winding insulation of IFM is substantially more stressed than of line-powered motors by surge voltages. Consequently, the winding insulation of IFM should be estimated by surge voltages. Also, the weakness of coil insulation can be detected by the surge voltage test. This paper described the insulation evaluation of induction motors by application of surge voltages. A surge voltage generator with the maximum voltage of 5 kV and the selectable rise-time in ranges of $50\;ns\;{\sim}\;500\;ns$ was fabricated. In the experiment, we applied surge voltages into induction motors with the magnitude and the risetime according to IEEE 522. By the analysis of applied surge voltage and current waveforms, we could find difference between normal and defection windings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.279-281
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• 1996

This paper deals with the two stage surge protection device by using varistor and LC low pass filter. Recently varistor alone has been used with overvoltage protection devices for the AC power mains and has same problems associated with high remnant voltage and noise. In this work, in order to improve the cutoff performance of surge protection device, the lightning surge protection device having two stage hybrid circuit for an AC single phase mains was designed and fabricated. Operation characteristics and surge clamping performance of the surge protection device in an $8/20{\mu}s$ surge current are investigated. As a consequence, it is found that the proposed two stage surge protective device for AC power mains has a variety of advantages such as a smaller clamping voltage, high frequency noise reduction and large clamping capacity.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.447-450
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• 2008

A storm surge is gradually increased in the Korean peninsula. Furthermore, this phenomenon is confined not only the Korean peninsula but also the whole world. A storm surge induced by storm, typhoon, or cyclone is a phenomenon that the water surface elevation is raising by the barometric pressure difference and this water level rising threatens the coastal facilities, settlement, or lives. Most of coastal region in our country are unsafe from this disaster. Even though we are not able to prevent the generation of this phenomenon, we can reduce the damages by investigating the kind of storm surge disaster. Once we finish this investigation, we can reduce the damages by offering the information for risk prior to an invasion of storm surge. This study, we analyzed the previously occurred storm surge damages, and this data can be utilized as a guide for those who live near the coastal region providing the information about the predicting scale of the storm surge

• 한국해안·해양공학회논문집
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• 제26권3호
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• pp.140-148
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• 2014

고조방파제는 폭풍해일이나, 대조시 창조류로부터 내부 해역을 보호하기 위하여 설계된 특수한 형태의 수문 구조물로, 홍수 방지 벽, 방조제 및 다른 구조물로 구성된다. 평상시 고조방파제는 해수 소통을 허용하지만, 폭풍해일이 예상되면 폐쇄된다. 폐쇄시키는 다양한 방법 중 본 연구에서는 이태리 모세프로젝트에 적용한 것과 같은 부유 플랩형 고조방파제를 마산만에 적용할 경우, 폭풍해일 및 파랑이 작용할 때의 고조방파제 거동특성을 3차원 유동해석프로그램인 FLOW-3D를 이용하여 살펴보았다. 수치해석결과, 고조차 2 m인 상태에서 파고 3 m 조건에서도 고조방파제로서의 기능을 발휘할 수 있는 것으로 평가되었다.

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.130-134
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• 2020

Metal oxide varistors (MOVs) protect circuits and devices from transient overvoltages in electric power systems. However, a MOV continuously deteriorates owing to manufacturing defects or repetitive protective operations from transient overvoltages. A deteriorated MOV may result in a short circuit or a line-ground accident. Previous studies focused on the analysis of deterioration mechanisms and condition diagnosis techniques for MOVs owing to their recent growth of use. An accelerated deterioration experiment under the same conditions in which a MOV operates is essential. In this study, we designed and fabricated a surge generator that can apply a surge current to a MOV connected to AC mains. The coupling network operates at a low impedance against the surge current from the surge generator and transfers the surge current to the MOV under test. It also acts as a high impedance against AC mains for the AC voltage not to be applied to the surge generator. The decoupling network operates at a high impedance against the surge current and blocks the surge current from AC mains. It also acts as a low impedance against AC mains for the AC voltage to be applied to the MOV under test. The prototype surge generator can apply the 8/20 us up to 15 kA on AC voltages in the approximate range of 110~450 V, and it fully operates on a LabVIEW-based program.