• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.24-28
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• 2010

The nuclear power Plant onsite AC electrical power sources are required to supply power to the engineering safety facility buses if the offsite power source is lost. Typically, Diesel Generators are used as the onsite power source. The 125 VAC buses are part of the onsite Class 1E AC and DC electrical power distribution system. The DC power distribution system ensure the availability of DC electrical power for system required to shutdown the reactor and maintain it in a safety condition after an anticipated operational occurrence or a postulated Design Base Accident. Recently, onsite DC power supply system trip occurs the loss of system function. To obtain the performance such as reliability and availability, we analyzed the cause of battery charger trip and described the improvement of DC power supply system reliability. Finally, we provide reliability performance criteria of charger in order to ensure the probabilistic goals for the safety of the nuclear power plants.

• Proceedings of the KIEE Conference
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• summer
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• pp.1208-1210
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• 2004

The Cold-Cathode Fluorescent Lamps (CCFL) are widely used to illuminate the liquid crystal displays(LCD) used in many battery powered instrument. This paper presents analysis of fly-back converter for universal-line applications($90\sim265Vac$) and half-bridge type resonant inverter for CCFL drive for stable characteristic and life improvement of fluorescent lamp operation frequency is higher than resonant frequency for safe operation. The validity of this study was confirmed from the simulation and experiential result.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.9
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• pp.537-544
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• 2002

This paper describes a comparative analysis of soft switching boost converters through design, production and experiment. Soft switching boost converters are designed to satisfy the condition of input voltage 170-265Vac, output voltage 400Vdc, output current 5A, output power 20W-2000W and unit power factor. In addition, parameter values are designed so that system operation can be compared under this is similar conditions. The efficiency of the combined inductor soft switching boost converter was 97.63% with 1011 load better than that of other boost converter types. The combined inductor soft switching converter has simple circuit construction and low switching loss. EMI resulted by the switching noise, and harmonic distortion.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.279-280
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• 2014

이 논문에서는 단상 디지털 역률 제어 보상 기법(PFC)을 제안한다. 제안된 방법은 인덕터 전류의 첨두값을 예측하고 기울기 보상 방법을 적용하여 제어기 출력을 생성함으로써 인덕터 전류의 첨두값을 제한하고, 스위칭 한 주기 안에 연속 도통 모드(CCM)과 불연속 도통 모드(DCM) 전류 제어를 완료한다. 따라서 기존 디지털 평균 전류 제어기에서 문제시 되었던 DCM-CCM 변환구간 즉 경계 도통 모드(BCM)에서 입력 전류 왜곡을 저감하였다. 제안된 제어기법의 유효성은 입력 전압 230Vac, 출력 전압 400V, 출력 750W급의 시제품 실험을 통해 검증하였다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.611-612
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• 2012

친환경자동차의 고전압시스템에 대한 인체 감전 사고 예방을 위한 전기안전 평가요소는 절연성능 평가이다. 고전압시스템을 사용하는 자동차의 절연성능은 $100{\Omega}/Vdc$, $500{\Omega}/Vac$ 이상으로 규정하고 있으며, 평가방법은 UNECE WP.29의 GTR 등에서 여러 가지 방법을 제시하고 있지만, 실차에 대한 측정을 통하여 몇 가지 문제점이 도출되었다. 본 연구에서는 실차상태의 절연성능 평가의 문제점 분석을 통하여 In Use 상태와 Post Crash 상태의 실차에 대한 절연성능 평가 방법을 제시하였다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.305-306
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• 2015

기존 소용량 전원 장치의 경우, Primary 측에 단상 AC 전압 평활을 위한 고압 전해 커패시터가 사용되는 것이 일반적이다. 이러한 전해 커패시터는 회로의 전체적인 부피를 키우고 제작 단가를 증가시킨다. 뿐만 아니라, 전원 열악 지역(인도향 제품 등)과 같이 300Vac 이상의 전압 한계치를 갖는 경우에는 전해 커패시터 파열에 의한 회로의 손상을 야기할 수 있다. 본 논문에서는 고압 DC 평활 커패시터를 삭제한 소용량 전원 장치 구현 방안을 제안한다. 제안 방식은 고전압 전해 커패시터의 삭제와 스위치 내장형 IC를 채용함으로써 소형화 및 원가 저감이 가능하며, 동시에 불안정한 입력 전원에도 전해 커패시터 파열에 의한 회로 손상을 막을 수 있다. 본 논문에서는 절연형 Flyback 컨버터를 이용하여, 이론적 특성 분석과 5W급 시작품을 통한 실험적 분석을 통해 그 타당성을 검증한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.127-128
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• 2005

UV-curable pressure sensitive adhesives were prepared by blending acrylic copolymer, copolymerized with butyl acrylate (BA), acrylic acid (AA) and vinyl acetate (VAc) by solution polymerization, triethyl amine (TEA) and trimethylolpropane triacrylate (TMPTA). The PSAs were evaluated by peel strength with varying contents of TMPTA and UV dose, and also glass transition temperature($T_g$) of PSAs were measured. When exposed on UV irradiation, the PSAs showed the decreased peel strength and increased $T_g$. And following UV irradiation, the PSAs did not leave any residue on wafer after peel off PSA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.6
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• pp.449-457
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• 2011

Effect of pump combinations on the vacuum characteristics of vacuum system was simulated for optimum design of system. In this investigation, the feasibility of modelling mechanism for VacSimMulti simulator was proposed. Simulation results of various pumping combinations showed the possibilities and reliabilities of simulation for the performance of vacuum system in specific semiconductor processing. Simulation of roughing pump presented the expected pumping behaviors based on commercial specifications of employed pumps. Application of booster pump exhibited the high pumping efficiency for middle vacuum range. Combinations of optimum backing pump for diffusion and turbo vacuum system were obtained. And, the predictable characteristics of process application of both simulated systems were also acquired.

• Bulletin of the Korean Chemical Society
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• v.18 no.5
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• pp.478-484
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• 1997

In a recent paper[Bull. Kor. Chem. Soc. 17, 735 (1996)] we reported results of molecular dynamic (MD) simulations for the thermodynamic and structural properties of liquid n-alkanes, from n-butane to n-heptadecane, using three different models. Two of the three classes of models are collapsed atomic models while the third class is an atomistically detailed model. In the present paper we present results of MD simulations for the dynamic properties of liquid n-alkanes using the same models. The agreement of two self-diffusion coefficients of liquid n-alkanes calculated from the mean square displacements (MSD) via the Einstein equation and the velocity auto-correlation (VAC) functions via the Green-Kubo relation is excellent. The viscosities of n-butane to n-nonane calculated from the stress auto-correlation (SAC) functions and the thermal conductivities of n-pentane to n-decane calculated from the heat-flux auto-correlation (HFAC) functions via the Green-Kubo relations are smaller than the experimental values by approximately a factor of 2 and 4, respectively.

• International journal of advanced smart convergence
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• v.10 no.1
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• pp.159-165
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• 2021

Electronic devices used in the mobile environments fabricated under the plasma conditions in high vacuum system. Especially for the development of advanced electronic devices, high quality plasma as the process conditions are required. For this purpose, the variable conductance throttle valves for controllable plasma employed to the high vacuum system. In this study, we analyzed the effects of throttle valve applications on vacuum characteristics simulated to obtain the optimum design modelling for plasma conditions of high vacuum system. We used commercial simulator of vacuum system, VacSim(multi) on this study. Reliability of simulator verified by simulation of the commercially available models of high vacuum system. Simulated vacuum characteristics of the proposed modelling agreed with the observed experimental behaviour of real systems. Pressure limit valve and normally on-off control valve schematized as the modelling of throttle valve for the constant process-pressure of below 10-3 torr. Simulation results plotted as pump down curve of chamber, variable valve conductance and conductance logic of throttle valve. Simulated behaviors showed the applications of throttle valve sustained the process-pressure constantly, stably, and reliably in plasma process.