• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.249-251
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• 2006

현재 전력계통해석은 단인 주파수의 정상 및 과도상태 해석용 페이서 개념의 해석 툴을 사용하고 있다. 이는 뇌서지, 개폐서지, TRV, 병렬회선 공진 등 비선형적 계통현상분석 시 한계를 보이게 된다. 더욱이 계통이 거대화, 복잡화 됨에 따라 비선형적 과도현상 발생 빈도가 더욱 증가하여 과도현상 해석의 필요성이 점점 증가하고 있는 실정이다. 전력계통 해석 소프트웨어 중 EMTP는 비선형적 요인에 의한 고장발생 시 원인분석 해석 기술을 제공하고 있다. EMTP-RV는 EMTP를 GUI 방식으로 재구성한 툴로서 더욱 사용하기 편한 장점을 지니고 있다. 따라서, 본 논문에서는 여러 과도현상 중 개폐서지에 대하여 EMTP-RV를 이용한 분석 기법을 나타내었다. 여러 개폐서지 발생 원인을 EMTP-RV를 이용하여 모델링 하였으며, 모의 결과를 분석하였다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1293-1297
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• 2015

This paper introduces the insulation coordination study results for UHV AC systems which was performed by CIGRE working group. The study results will be discussed within IEC technical committee in order to amend the IEC Insulation Coordination 60071-1 Ed. 8 2010 and 60071-2 Ed. 3, 1996. This paper includes the insulation coordination of transformer, gas insulated switchgear, metal oxide arresters and clearances of transmission towers. This article also illustrates the overvoltage specific to UHV systems such as TOV(temporary overvoltage), switching overvoltage, lightning overvoltage and VFTO(very fast transient overvoltage).

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.305-308
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• 2008

This paper presents characteristics of soil ionization when high currents such as lightning and switching surge currents are injected into a grounding rod. Soil ionization phenomena are investigated by using both voltage and current signals recorded by oscilloscope. As a result, a critical electric field intensity($E_C$) for ionization is decreased with reduction of grain size. The pre-ionization resistance($R_1$) and post-ionization resistance($R_2$) at the sand with fine grain size are getting lower with increasing current magnitude. Finally, the time to ionization($t_1$) and ionization current peak($t_2$) of fine grain size are significantly shorter than those of medium grain size.

• 한국컴퓨터산업교육학회:학술대회논문집
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• 한국컴퓨터산업교육학회 2003년도 제4회 종합학술대회 논문집
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• pp.17-22
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• 2003

The surge of Internet traffic makes the bottleneck nowadays. This problem can be reduced by substituting the media of network, routers and switches with more high-performance goods. However, we focused radically the server performance of processing the service requests. We prepose the method improving performance of server in the Linux kernel stack. This accelerator accepts the requests from many clients, and processes them using not user threads but kernel thread. To do so, we can reduce the overhead caused by frequent calling of system calls and the overhead of context switching between threads. Furthermore, we implement CPN(Coloured Petri Net) model. By using the CPN model criteria, we can analyze the characteristics of operation times in addition to the reachability of system. Benchmark of the system proves the model is valid.

• Journal of Power Electronics
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• 제2권3호
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• pp.189-198
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• 2002

New concept of energy recovery for plasma display panel (PDP) Is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel Polarity together with energy Previously charged in Panel capacitance. This operation Provides zero -voltage-switching of switches and reduction of EMI by rejecting the surge current when the sustain switches are turned on. The build-up current helps to reduce transition time of panel polarity and may produce more stable light waveforms. This method shows a desirable characteristic that the circuit loss is similar to that of series resonant type energy recovery circuit which is very effective method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1578-1582
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• 1998

The ground potential rise generated by the switching surge or lightning stroke may be dangerous to personnel and cause damage to electronic control parts. For a first step to the transient performance analysis. high frequency impedances of grounding grids have been calculated and discussed. Grounding grids include 7 square grids from $10m{\times}10m$ to $80m{\times}80m$. The high frequency current was injected into the center and a corner of the grounding grid. The calculation results indicate that the impedance of the grounding grid is significantly influenced by frequency and the point of injection of the current. and the effective radius of a large grounding grid may be represented in $15{\sim}20m$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1770-1772
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• 1997

In this paper, Voltage-time characteristics of lightning impulse and switching surge breakdown in SF6 is studied on the gap and various pressure. The characteristics is categorized into three pattern depending on the configuration of the gap and gas pressure. The properties of the voltage-time characteristics in these patterns are generalized as semi-empirical formula which will be useful in the quantitation voltage evaluation of insulation coordination and the abnormal voltage protection of SF6 insulated power equipment.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.159-167
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• 1999

This paper presents a new transient voltage blocking device(TOBD)which low power and high frequency bandwidth to protect info-communication facilities from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth low ener-gy capacity and high remnant voltage. in order to improve these limitations a hybrid type TOBD which consists of a gas tube avalanche diodes and junction type field effect transistor (JFETs) is developed. The TOBD differs from the conventional protection devices in configuration and JFETs are used as an active non-linear element and a high speed switching diode with low capacitance limited high current. Therefore the avalanche diode with low energy capacity are protected from the high current and the TOBD has a very small input capacitance. From the performance test using combination surge generator which can produce $1.2/50{\mu}m$ 4.2 kV/max, $8/20{\mu}m$ 2.1 kAmax it is confirmed that the proposed TOBD has an excellent protection per-formance in tight clamping voltage and limiting current characteristics.

• ETRI Journal
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• 제35권4호
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• pp.603-609
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• 2013

In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.

• 조명전기설비학회논문지
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• 제24권10호
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• pp.33-41
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• 2010

There are several overvoltages by abnormal conditions in power system. We need to calculate these ovevoltages for the insulation design and the fault analysis. For these calculations, we used EMTP(Electro-magnetic Transients Program). During EMTP calculations, the accurate modelling of the equipments is very important for analysis results. In this paper, we considered the effects of the modelling condition's changes for transmission line within EMTP modelling cases of overvoltage analysis. Specially, we considered CB closing cases of 765[kV] system. So, we had changed the calculation frequencies of Line Constants, which is used for CB closing cases. In addition, we compared the calculation result and the measured result.