• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.230-231
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• 2012

This paper describes a gate driver that operates numerous semiconductor switch in the solide-state pulsed power modulator. the proposed gate driver is designed to receive both the isolated drive-power and the on/off pulse signals through the transformer. Moreover, the IGBT-switch can be quickly turned off by adding protection circuit. Therefore it protects the IGBT-switch from the arc condition that frequently occurs in high-voltage pulse application. To comprehend operating characteristic of each IGBT-switch in pulse output condition, the device consisting of a high efficiency soft-switching capacitor charger and two series stacking IGBT-switch is developed. Finally, the relability of the proposed gate driver and the device for its test are proved through PSpice simulation and experiments.

• 전력전자학회논문지
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• 제8권1호
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• pp.24-29
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• 2003

현재 120kV/70A 고압 스위치가 KSTAR의 NBI 시스템에 사용되기 위하여 대전의 원자력 연구소에 설치되어 있다. NBI 시스템은 아크 발생시 이온 소스를 보호하기 위하여 전압의 빠른 차단 및 빔 전류의 유시를 위하여 전압의 빠른 턴온이 요구된다. 따라서 고압 스위치와 아크 검출회로는 NBI 시스템에서 중요한 부분을 차지하고 있다. 고압의 반도체 스위치는 NBI 시스템 뿐만 아니라 산업전반에서 요구되고 있다. NBI 시스템에 적용된 120kV/70A 고압 스위치는 100개의 MOSFET 소자를 직렬연결하였으며 본 논문에서 제안한 바이어스 전원이 없는 간단한 구동회고를 사용하였다. 실험식에서의 시험 및 현장에서 100kW의 모의 저항부하와 NBI 이온 소스에 적용한 실험결과를 제시하였다. 본 논문은 120kV/70A 고압 MOSFET 스위치와 간단한 게이트 구동회로의 설계를 제시하였으며, 제작 및 시험기간 동안의 문제점 및 해결방안에 대해서도 제시하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.219-219
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• 2009

ceramic metal halide lamps are a subset of high intensity discharge lamps so named because of their high radiance These lamps weak ionized plasma in a fire-resisting but light transmissive wrapping by the corridor of current through atomic and molecular vapors. for commercial applications, For commercial applications, the conversion of electric power to light must occur with good efficiency and with sufficient spectral content throughout the visible (380-800 nm) to permit the light so generated to render colors comparable to natural sunlight. the purpose of this paper is to carry out a study on the variation of ageing time(2000 On/Off[hr]) on the performance of 150W CMH lamps. Experimental results show that the blackening by reacting W(tungsten)with I atomic has been created in the arc tube of an ageing lamp(2000 On/Off[hr]), the arc was unstable, and increased a lamp resistance made lamp voltage increases significantly. Also, Color temperature of the ageing lamp was moved by the losses of Ho with Dy atomics and by recombination of Na with I.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.359-365
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• 2006

Since the start of the KSTAR (Korea Superconducting Tokamak Advanced Research) project, Instrumentation and Control (I&C) of the Neutral Beam Test Facility (NB-TF) has been striving to answer diverse requests arising from various facets during the project's development and construction phases. Hard-wired electrical circuits have been designed, tested, fabricated, and finally installed to the relevant parts of the system. In relation to the vacuum system I&C, controlling functions for the rotary pumps, a Roots pump, two turbomolecular pumps, and four cryosorption pumps have been constructed. I&C for the ion source operation are the temperature and flow rate signal monitoring, Langmuir probe signal measurements, gradient grid current measurements, and arc detector circuit. For the huge power system to be monitored or safely operated, many temperature measurement functions have also been implemented for the beam line components like the neutralizer, bending magnet, ion dump, and calorimeter. Nearly all of the control and probe signals between the NB test stand and the control room were made to be transmitted through the optical cables. Failures of coolant flow or beam line vacuum pressure were made to be safely blocked from influencing the system by an appropriate interlock circuit that will shut down the extraction voltage application to the system or prevent damages to the vacuum components. Preliminary estimation of the beam power through the calorimetric measurement shows that 87.9% of the total power of the 60kV/18A beam with 200 seconds duration is absorbed by the calorimeter surface. Most of these I&C results would be highly appropriate for the construction of the main NBI facility for the KSTAR national fusion research project.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.38-40
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• 2009

In order to achieve a gearless construction of the wind energy conversion system(WECS), a low-speed generator should be used. Of the various candidate machine types, radial-field, multi-pole, permanent magnet, synchronous machines may be used for low-speed applications. So, this paper deals with the design of direct-coupled, multi-pole radial field machines with permanent magnet(PM) excitation for wind power applications for cogging torque reduction through the determination of optimum pole arc/pitch ratio. On the basis of an equivalent magnetic circuit method(EMCM) and a space harmonic method(SHM), an initial design is performed considering restricted conditions. And then, a detailed design is made using a non-linear finite element analyses(FEA). Finally, test results concerning generating characteristics are given to confirm the validation of the design.

• 대한전기학회논문지:전력기술부문A
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• 제55권11호
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• pp.468-475
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• 2006

This paper reviews the energy characteristics of oil filled cables in transient state such as grounding fault and lightning surge. Artificial grounding fault test was firstly performed in 2003 for the analysis of arc voltage and breakdown energy according to the fault current. In this paper, energy of OF cable is variously analysed at joint box based on the actual test. Then more various conditions such as installation types, section lengths and CCPU(Cable Covering Protection Unit) connection types are applied for the simulation using EMTP when the single line to ground fault and direct lightning stroke are occurred on actual underground power cable systems and combined power cable systems, respectively. Finally, the energy by the length of crossbonded lead and grounding lead as well as fault lasting time is also calculated using EMTP simulation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.445-450
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• 2003

This study was performed 10 develop the accelerated life test method using Weibull-IPL(Inverse Power Law) model for mechanical components. Weibull-IPL model is concerned with determining the assurance life with confidence level and the accelerated life test time From the relation of weibull distribution factors and confidence limit, the testing times on the no number of failure acceptance criteria arc determined. The mechanical components generally represent wear and fatigue characteristics as a failure mode. IPL based on the cumulative damage theory is applied effectively the mechanical components to reduce the testing time and to achieve the accelerating test conditions. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% confidence level for one test sample. According to IPL, because test time call be shorten in case increase test load test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.51-51
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• 2010

Recently just as in the automobile industry, shipbuilders also try to reduce material consumption and weight in order to keep operating costs as low as possible and improve the speed of production. Naturally industry is ever searching for welding techniques offering higher power, higher productivity and a better quality. Therefore it is important to have a details research based on the various welding process applied to steel and other materials, and to have the ability both to counsel interested companies and to evaluate the feasibility of implementation of this process. Submerged-arc welding (SAW) process is usually used about 20% of shipbuilding. Similar to gas metal arc welding(GMAW), SAW involves formation of an arc between a continuously-fed bare wire electrode and the work-piece. The process uses a flux to generate protective gases and slag, and to add alloying elements to the weld pool and a shielding gas is not required. Prior to welding, a thin layer of flux powder is placed on the work-piece surface. The arc moves along the joint line and as it does so, excess flux is recycled via a hopper. Remaining fused slag layers can be easily removed after welding. As the arc is completely covered by the flux layer, heat loss is extremely low. This produces a thermal efficiency as high as 60% (compared with 25% for manual metal arc). SAW process offers many advantages compared to conventional CO2 welding process. The main advantages of SAW are higher welding speed, facility of workers, less deformation and better than bead shape & strength of welded joint because there is no visible arc light, welding is spatter-free, fully-mechanized or automatic process, high travel speed, and depth of penetration and chemical composition of the deposited weld metal. However it is difficult to application of thin plate according to high heat input. So this paper has been focused on application of the field according to SAW process for thin plate in ship-structures. For this purpose, It has been decided to optimized welding condition by experiments, relationship between welding parameters and bead shapes, mechanical test such as tensile and bending. Also finite element(FE) based numerical comparison of thermal history and welding residual stress in A-grade 3.2 thickness steel of SAW been made in this study. From the result of this study, It makes substantial saving of time and manufacturing cost and raises the quality of product.

• 한국안광학회지
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• 제20권1호
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• pp.61-66
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• 2015

목적: 본 연구에서는 하워드-돌먼 입체검사(Howard-Dolman test, HDTEST, Bernell, U.S.A)를 이용하여 20대 성인의 동적 입체시를 측정하여 남녀 간의 동적 입체시를 비교하고, 동공 간거리(PD; pupillary distance)와 좌우안의 구면굴절력의 차이로 인한 굴절부등과 동적 입체시의 상관관계를 분석해 보고자 하였다. 방법: 평균연령이 $22.68{\pm}0.50$(20~29)세인 20대 성인 63명(남자 30명, 여자 33명)을 대상으로 실험을 실시하였다. 굴절이상자는 완전교정을 한 후에 Howard-Dolman test(H-D Test)를 이용하여 2.5 m 검사거리에서 동적 입체시를 각각 5회 측정하였다. 결과: 전체 대상자의 동적 입체시의 평균은 $28.44{\pm}25.03$초였고, 이들 중 남자는 $28.23{\pm}23.34$초, 여자는 $28.63{\pm}26.83$초였다. PD 범위를 기준으로 한 동적 입체시에 있어서 PD가 59.80 mm이하 범위에서는 $33.87{\pm}18.53$초, 59.81~66.15 mm의 범위에서는 $26.24{\pm}25.26$초, 66.15 mm를 초과하는 범위에서는 $34.60{\pm}25.65$초로 나타났고, 유의한 차이는 보이지 않았다(P=0.73, r=0.03). 굴절부등의 차이를 기준으로 할 때 동적 입체시는 굴절부등이 1 D미만인 경우 $26.81{\pm}24.86$초, 1 D이상인 경우는 $1.45{\pm}24.18$초였고 유의한 차이는 없었다(P=0.15, r=0.15). 결론: H-D test를 이용해 20대 성인의 동적 입체시를 평가해 보았을 때, 남녀 간에 큰 차이가 없고, PD와 굴절부등은 동적 입체시에 큰 영향을 주지 않는 것으로 나타났다.

• 조명전기설비학회논문지
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• 제25권7호
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• pp.92-96
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• 2011

In this paper, in order to reduce the electrical disaster such as electrical fire at traditional markets, we need to develop the ESMS(electrical safety monitoring system) which is able to monitor the power status of electrical equipments. Therefore, for solving the those problems, we developed the detection censor(ZCT, CT) and equipment of data analysis and transmission. The detection censor and equipment are able to monitor the electrical equipments condition(over current, leakage current, arc, etc.). We constructed Test-Bed for testing reliability of the ESMS and obtained certification. And we tested the over current, leakage current and arc under the normal condition.