• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.16-21
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• 2017

Fire or electrical problem while DC electric traction vehicle operation caused by various reasons can lead to not only suspension of the operation, but also severe aftermath such as massive casualty. In this paper, fire analysis on DC electric traction vehicle caused by electrical breakdown on line breaker, which is in connection with the power supply, is presented. When the electric arc, the by-product of frequent line breaker operation, is not fully diminished, it leads to electrical breakdown and fire. Especially, electrical breakdown can be easily induced by the open-and-close operation of inner contractor inside line breaker, eventually followed by ground fault and generation of transient current. Electric arc is consequent on the ground fault and acts as possible ignition source, leading to fire. Also, during the repetitive operation of the line breaker, the contactor is separated each other and some copper powder is generated, and the copper powder provided breakdown path, resulting in fire.

• International Journal of Safety
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• v.8 no.2
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• pp.9-14
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• 2009

This paper describes analysis of risk voltage for grounding electrode where earth leakage current is injected. To assess risk voltage of grounding electrode, the grounding simulator and CDEGS program were used to obtain measured data and theoretical results of this study. The grounding simulator was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The shapes of grounding electrode model was ground rod. The potential rise was measured by grounding simulator, and the touch and step voltages were computed by CDEGS program. As a consequence, the potential rise of ground rod abruptly decreases with increasing the distance from the grounding electrode to the point to be tested. The touch voltage above the ground rod was low, but the step voltage was high. The measured results were compared with the computer calculated data and were known in good agreement.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.3
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• pp.395-405
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• 2024

This study provides a thorough examination of Unmanned Ground Vehicles(UGVs), focusing on crucial technologies and trends across major global markets. It includes an in-depth patent analysis revealing the dominant positions of the United States and the European Union in this field. Additionally, it underscores substantial advancements made by China, Japan, and Korea since 2010. Using Latent Dirichlet Allocation(LDA)-based patent text mining, the study identified key technology areas in UGV development, such as advanced control systems, navigation technologies, power supply mechanisms, and sensing and communication tools. Through linear regression analysis, the study predicted the future paths of these technology areas, offering important insights into the evolving world of UGV technology. The findings can provide strategic guidance for stakeholders in the defense, commercial, and academic sectors, pointing out the future directions in UGV advancements.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.231-233
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• 1991

This paper discribes a study on the switching character of MOS-GTO and the design of gate drive circuit. Chopping power supply converter, synchronious and asyncronious motor speed adjustment, inverter, etc., needs low drive energy "high frequency" switches. To fulfill these need, switches must have rapid switching time and insulated gate control. MOS-GTO structure is well suited to these constraints. The power switch is serial installation of a GTO thyrister and a MOS Transistor. The gate of the GTO is linked to positive pole of the cascode structure via a MOS high voltage transistor and ground via a transient absorber diode. This high performance MOS-GTO assembly considerably increases the strength which facilitate the drive of GTO thyristers.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.90-94
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• 2009

The inundation of substation and ground power equipment breaks out every summer season in low-lying downtown and low-lying shore by localized heavy rain, typhoon and tidal wave. For diminishing flood damage of electrical equipment in the root, flood protection system which is used the basic frame of Pad transformer is developed using pneumatic pressure. This system is established on pressure generator equipment and sensor of flooded level operates at flooding occurrence and is maintained a shutting tightly structure. The system is able to protect indraft water in Pad Transformer and supply the electricity at emergency(flooding). And we tested safety for insulation resistance at flooding and applying an electrical current. We estimate that loss cost which is caused by with flooding and the power failure will be diminished if it is addition to advances the reliability evaluation by setting an example.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1720-1725
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• 2008

Because of the continuous increasing of energy consumption, metallic pipelines are widely used to supply services to customers such as gas, oil, water, etc. Most common metallic pipelines are underground and are now frequently being installed in nearby electric power lines. In recent years, buried gas pipeline close to power lines can be subjected to hazardous induction effects, especially during single line to ground faults. because it can cause corrosion and it poses a threat to the safety of workers responsible for maintenance. Accordingly, it is necessary to take into consideration for analysis of induced voltage on gas pipelines in transmission lines. This paper analyzed the induced voltage on the gas pipelines due to the 154kV transmission lines in normal case and in different faulty case conditions using EMTP (Electro-Magnetic Transients Program).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.50-58
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• 2011

In this paper, potential distribution analysis through the six kinds of case studies examined in the environmental conditions change within a limited space, by the power supply system installed. To interpret the potential distribution using electromagnetic field analysis program and the parameters were state of the ground, the outer wall of the configuration state and the presence of human potential distribution was simulated. Potential distribution analysis, the size of nominal voltage, depending on the impedance of human body to be determined on the impact of surprise decision, but if equipped with appropriate protective equipment can be protected from lightning have been confirmed.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.12
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• pp.561-565
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• 2001

Recent trend of increasing automated factories needs supply of high quality power from the utilities. Among the items of the power quality, voltage sag can be compensated by Dynamic Voltage Restorer(DVR). The key feature of the DVR is high response with less transient period to recover from the voltage sag due to the lightning or line-to-ground faults. In this paper we report that $H_{\infty}$ controller is very promising for the practical application to the controller of DVR. Experimental results shown in this paper was obtained by applying the control algorithm to 20 kVA DVR system. The experimental set consists of IGBT-based three phase inverter and the TMS320C32-60 DSP used for main processor of the control board. To simulate the 50% voltage sag, the SCR-based experimental set was constructed.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.54-55
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• 2014

일반적으로 지상 로봇의 주 전원으로 사용되는 대용량 배터리가 예상치 못한 시점에 방전되거나 고장으로 인해 전원 공급이 되지 않을 경우 지상 로봇의 위치 확인이 필요하게 된다. 이에 따라 본 논문에서는 이 통신용 비상 전원 공급을 위한 태양광 및 연료전지 전원 공급 장치와 이 장치를 보완하여 사용할 수 있는 배터리 충 방전 하이브리드 시스템을 설계하고, 이를 시뮬레이션과 실험을 통해 타당성을 검증 및 분석하도록 한다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.178-183
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• 2000

Electrorheological(ER) effect on the dispersive system of polarizable fine powder/dielectric oil has been investigated. The electrical and rheological properties of zeolite and starch based ER fluid were reported. The ER fluids were constructed by mixing zeolite and starch power with two different dielectric oils. Yield stress of the fluids were measured on the couette cell type rheometer as a function of electric fields, particle concetrations, and temperatures. The electric field is applied by high voltage DC power supply. The outer cup is connected to positive electrode(+) and the bob becomes ground(-). And the temperatures the viscosity(or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to $200s^{-1}$ in 2 minutes.