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군집화 알고리즘을 이용한 배전선로 내부 열화 패턴 분석
최운식,김진사,Choi, Woon-Shik,Kim, Jin-Sa 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.1
Degradation in power cables used in distribution lines to the material of the wire, manufacturing method, but also the line of the environment, generates a variety of degradation depending upon the type of load. The local wire deterioration weighted wire breakage accident can occur frequently, causing significant proprietary damage can lead to accidents and precious. In this study, the signal detected by the eddy current aim to develop algorithms capable of determining the signals for the top part and at least part of the signal by using a signal processing technique called K-means algorithm.
열처리 방법에 따른 세라믹 박막의 AFM 및 C-F 특성
최운식,Choi, Woon-Shik 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.9
The $Sr_{0.7}Bi_{2.3}Nb_2O_9(SBN)$ thin films are deposited on Pt electrode($Pt/Ti/SiO_2/Si$) using RF sputtering method at various deposition temperature. The deposition temperature of optimum was $300^{\circ}C$. SBN thin films were annealed at $500{\sim}700^{\circ}C$ using furnace and RTA, respectively. The surface roughness showed about 2.42 nm in annealing temperature($600^{\circ}C$) of furnace. The capacitance density of SBN thin films were increased with the increase of annealing temperature. The maximum capacitance density of $0.7{\mu}F/cm^2$ was obtained by annealing temperature($700^{\circ}C$). The frequency dependence of dielectric loss showed about 0.03 in frequency ranges of 1~1,000 kHz.
나노실리카 충진함량 변화에 따른 EMNC의 특성연구 (1) -열적특성 중심으로-
최운식,박재준,Choi, Woon-Shik,Park, Jae-Jun 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.10
This paper focuses on thermal properties of a newly prepared composite material by nano-silica and micro-silica mixture. Nano-silica and micro-silica mixture composites were made by dispersing surface treated nano-silica(average radius: 10 nm) and micro-size silica in epoxy resin. To investigate the effects of nano-silica and micro-size silica mixture(ENMC), the glass transition temperature (Tg), coefficients of thermal expansion(CTE) and elastic modulus of DMA properties by DSC, TMA and DMA devices were measured for the ENMC according to increase nano-silica addition contents and EMC. All properties of the neat epoxy were improved by the addition of micro-silica, which was improved much further by the addition of surface treated nano-silica to the EMC system.
최운식(Woon-Shik Choi),김탁용(Tag-Yong Kim),김진사(Jin-Sa Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.6
Recently, important for the safety has been increasing together economic developments. The leakage only is measured by the voltage difference. This method is a way to contact the electric leakage area. It can cause electric shock at users. We propose a non-contact method to detect a short circuit in this paper. We investigate magnetic field at electric leakage area to present non-contact method. Simulated environment created a short circuit in the flooded areas. Voltage is supplied 50, 150 and 200[V]. Magnetic field was measured at 0, 5 and 10[㎝]. Magnetic flux was reduced about 0.4[μT/㎝] depending on the distance changes in the steady region. But we confirmed that magnetic flux is measured the same value depending on the distance changes in the electric leakage area.
$Ar/O_2$비에 따른 $Sr_{0.7}Bi_{2.3}Nb_2O_9$ 박막의 구조 및 영향
김진사,최운식,Kim, Jin-Sa,Choi, Woon-Shik 한국반도체디스플레이기술학회 2009 반도체디스플레이기술학회지 Vol.8 No.2
The $Sr_{0.7}Bi_{2.3}Nb_2O_9$(SBN) thin films are deposited on Pt-coated electrode(Pt/Ti/$SiO_2$/Si) using RF sputtering method at various $Ar/O_2$ ratio. We investigated the effect of deposition condition(specially $Ar/O_2$ ratio) on the structural properties of SBN thin film. As $Ar/O_2$ ratio was increased, the peaks in the XRD pattern became more sharp. Also, the peaks(008)(115)(220) in 80/20 of $Ar/O_2$ ratio were suddenly appeared. The optimum of the rougness showed about 4.33 nm in 70/30 of $Ar/O_2$ ratio. The crystallinity of SBN thin films were increased with the increase of $Ar/O_2$ ratio. Also, Deposition rate of SBN thin films was about 4.17 nm/min in 70/30 of $Ar/O_2$ ratio. The capacitance of SBN thin films were increased with the increase of $Ar/O_2$ ratio.
오재준,최운식,최성주,Oh, Jae-Jun,Choi, Woon-Shik,Choi, Seong-Ju 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.10
Lamination is used extensively in various industries. The type of lamination applied to the material depends on the precision level required, which varies for materials needed for everyday use, materials used in high-tech industries, and processes employed to fabricate finished products. Especially in hot lamination, the distribution of the surface temperature of the heating roller is very important to avoid the generation of internal bubbles and ensure flatness of the attached materials, and thus maintain a good standard of quality and productivity. In this study, we have developed a system to monitor the surface temperature of the heating rollerby applying a heterogeneous controller and a non - contact temperature sensor. This monitoring system accurately measures the surface temperature of the heating roller and applies the RS485 MODBUS communication method for easy expansion. Using this system, a laminated prototype was fabricated, and its efficacy for non-contact temperature sensor calibration, Ethernet IP communication, stoppage of the heating roller, and determination of temperature distribution with rotation was examined for its potential usage in industries.
시스템 LED 조명의 전기적·열적 안전성 확보 방안에 대한 연구
김영우,김충혁,최운식,Kim, Yeong Woo,Kim, Chung Hyeok,Choi, Woon Shik 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.5
This study tested the electrical, structural, and thermal safety of LED lighting products, available on the market. Five recessed LED systems, 20 W each, and five fixed LED systems, 25 W each, were selected. Dielectric strength tests, live part electric shock protection tests, and thermal tests were conducted on the LEDs. These were key tests for user safety, according to the specification of the safety criteria for electric products, KC 60598-1, South Korea. In addition, the wiring temperature of UL1007, 60227 IEC 08, and UTP cables, was measured. The results of the study gave an in-depth examination of the safety of LED lighting systems for users.
김진사(Jin-Sa Kim),최운식(Woon-Shik Choi),김충혁(Chung-Hyeok Kim) 대한전기학회 2009 전기학회논문지 Vol.58 No.3
The Sr0.7Bi2.3Nb₂O?(SBN) thin films are deposited on Pt-coated electrode(Pt/Ti/SiO₂/Si) using RF sputtering method at various deposition temperature. The optimum conditions of RF power and Ar/O₂ ratio were 60[W] and 70/30, respectively. Deposition rate of SBN thin films was about 4.17[㎚/min]. The crystallinity of SBN thin films were increased with increase of deposition temperature in the temperature range of 100~400[℃], the surface rougness showed about 4.33[㎚]. The capacitance of SBN thin films were increased with the increase of deposition temperature.