• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.989-994
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• 2002

In case the fault occurs in railway high voltage power supply network, protective relaying system must selectively detect 1 wire ground fault of grounding or non-grounding system. And this study presents railway high voltage power supply system model using PSCAD/EMTDC Vet 3.08 for circuit analysis and fault studies. In this paper, we propose protection method of non-grounding system of railway high voltage power supply system. The result shows its usefulness.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.995-1000
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• 2002

This paper presents general concept of DC switch gear(DCSWGR). Normally, DCSWGR consist of Digital protection unit(DPU), High Speed Circuit Breaker(HSCB), Disconnect Switch (DS), Programmable Logic Control(PLC), Auxiliary Relays and etc. Most of the components has its special characteristics and their interface between each others are various and complex. In this paper every constituent general design are preceded and interface between each component are examined. And also DCSWGR operation logic with logical diagram including interlock signal are introduced.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.344-351
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• 1999

The safe operation of electro railways is greatly dependant on its protective systems. The system so-called Fault Protection Wire(FW) is now widely adapted to protect in AT feeding systems. It is connected between the feeder and trolley circuit to return the fault current to autotransfonmers at substation. This paper computed the distribution of fault currents at FW in the system and also evaluated the safety from electric shock when ground fault or flashover occur in the feeding system. The results show FW is useful to protect power supply network from fault in electric railways

• 한국화재소방학회논문지
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• 제30권4호
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• pp.111-120
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• 2016

본 논문은 휴대폰 배터리의 폭발 및 화재 위험성을 분석하기 위한 실험적 연구로서, 실험은 스마트폰 배터리로 사용되고 있는 리튬-이온 배터리를 대상으로 하여 사용상 부주의 또는 이상상태 등에서 폭발 및 화재가 발생될 가능성이 있는 과충전, 내부단락 및 외부단락 그리고 열충격에 의한 실험을 진행하였다. 리튬-이온 배터리는 과충전 및 외부단락 실험의 경우 보호회로가 정상적으로 작동될 때는 폭발 및 화재 위험성이 없었으나, 보호회로가 고장상태를 가정하였을 때 폭발 및 화재 위험성이 크게 나타났다. 내부단락 및 열충격 실험의 경우 충전상태에 따라 위험성에 차이가 나타났다. 즉, 완방전 상태에서는 폭발 및 화재 위험성이 낮았으나, 완충전 상태에서는 폭발 및 화재 위험성이 높게 나타나는 것을 확인할 수 있었다. 실험결과 휴대폰 배터리의 폭발 및 화재 위험성을 최소화하기 위해서는 보호회로 고장시 알람장치 및 배터리 케이스 강화 그리고 고온방지를 위한 냉각장치 등의 안전장치의 강화가 필요할 것으로 생각된다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.298-302
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• 2005

This paper presents the protection effect of SPDs according to installation conditions. To develop the effective protection countermeasures of information and communication equipments against lightning surges, actual-sized experiments in relation to the protection effects on the installation positions of surge protective devices(SPDs), the length of branch circuit the materials and long of conduit were conducted. The best method for protecting the electronic equipments from surges is to install the SPD at the front point of the devices to be protected. The installation method of the metal conduit bonded with common ground conductor were more effective than that of the PVC conduit.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.90-95
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• 2015

This paper describes IEC 61727 standard of Photovoltaic (PV) systems -Characteristics of the utility interface. IEC 61727 standard tests include utility compatibility and personnel safety and equipment protection of PV inverter performance functions. Especially utility compatibility part includes test items of 1) voltage, current and frequency, 2) normal voltage operating range, 3) flicker, 4) DC injection, 5) normal frequency operating range, 6) harmonics and 7) waveform distortion, 8) power factor of PV inverter. Also personnel safety and equipment protection part includes test items 1)loss of utility voltage, 2)over/under voltage and frequency, 3)Islanding protection, 4)response to utility recovery, 5)earthing, 6)short circuit protection, 7)Isolation and switching of PV inverter. In this paper, each item of IEC 61727 standard test is studied and analyzed and finally full tested by PV inverter performance function.

• ETRI Journal
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• 제31권6호
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• pp.725-731
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• 2009

In this paper, electrostatic discharge (ESD) protection circuits with an advanced substrate-triggered NMOS and a gate-substrate-triggered NMOS are proposed to provide low trigger voltage, low leakage current, and fast turn-on speed. The proposed ESD protection devices are designed using 0.13 ${\mu}m$ CMOS technology. The experimental results show that the proposed substrate-triggered NMOS using a bipolar transistor has a low trigger voltage of 5.98 V and a fast turn-on time of 37 ns. The proposed gate-substrate-triggered NMOS has a lower trigger voltage of 5.35 V and low leakage current of 80 pA.

• Journal of Radiation Protection and Research
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• 제25권4호
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• pp.197-205
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• 2000

실리콘 PIN 다이오드 검출기를 이용하여 전자선량계(PED)를 설계 및 제작하고, 전자신호회로의 성능과 방사선 검출 반응특성을 평가하였다. 전자회로의 성능검사에서는 방사선에 의한 검출기의 신호가 신호처리회로에서 양호하게 출력되었으며, $^{137}Cs$ 감마 방사선을 이용한 방사선조사 시험결과 선량계의 반응도 및 분산계수는 각각 1.85 cps/$Gy{\cdot}h^{-1}$ 및 19.3%로 측정되어 전자선량제의 성능기준을 만족하는 것으로 나타났다. 본 전자선량계의 시작품은 향후 전자회로의 성능향상과 작동 프로그램을 보완 및 개선함으로써 개인 방사선 모니터링에 활용될 것으로 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.958-960
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• 2002

High Temperature Superconducting (HTS) devices make it possible to operate with no electrical loss by resistance. If, however, the applied current is over its critical current, the phase of HTS devices is changed to normal state, so called, quench. In this case, since resistance of HTS is increased abruptly, it can not be avoidable to damage the whole apparatus. In this study, quench detector to protect HTS devices was proposed. We designed the quench detecting circuit and tested the performance of the circuit. The detecting circuit was consisted of Op-Amp and low pass filter etc, to detect very low voltage around $1{\mu}V$. The circuit detected effectively the low voltage when over current is applied to HTS tapes. At the next step, we are going to apply and test the circuit to protect the prototype HTS cable.

• 대한의용생체공학회:의공학회지
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• 제27권6호
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• pp.343-350
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• 2006

Medical magnetic stimulator generates strong magnetic field pulses. Clinical applications of the magnetic pulse are the stimulation of nervous system and the contraction of muscle. The unique source of the strong magnetic pulse is a capacitor-inductor resonator and this inductor generates a strong sinusoidal magnetic pulse by discharging the capacitor with high initial voltage. Continuous muscle contraction needs sequential generation of the magnetic pulses. However, to keep the magnitude of sequential pulses identical, an expensive high-voltage power supply have to support voltage drop of the capacitor between the pulses. A protection circuit between the supply and the resonator is necessary to protect the supply from reverse current caused by capacitor voltage reversal. In this paper, a new circuit structure of the magnetic stimulator adopting a low-frequency fly-back switching is proposed. The new circuit supports sequential pulse generation and allows the reverse current without damage. Performance of the new circuit is examined and a low-cost magnetic stimulator for urinary incontinence therapy is being developed using the presented method.