• 전력전자학회논문지
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• 제17권1호
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• pp.21-26
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• 2012

In recent years, DC distribution systems are becoming hot issue due to the increase in digital loads and DC generation systems according to the expansion of renewable energy technologies. However, removing the fault current in DC grids is comparably difficult since the current in DC grids has no zero-crossing point like in AC grids. Thus, developing dedicated DC circuit breakers for DC grids is necessary to get safety for people and electrical facilities. This paper proposes magnet arc extinguishing method to develop a 300[$V_{DC}$]/10[A] DC circuit breaker. The performance of the proposed DC circuit breaker was verified by an experimental circuit breaker test system built in this research.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1936-1938
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• 2005

$Al(OH)_3$ is added to the silicone rubber for improvement of its resistance against surface discharge. In this paper, four kinds of $Al(OH)_3$ were added to the SIR during compounding. SIR was deteriorated by a corona treatment. Hydrophobicity recovery rate after corona treatment and arc resistance of SIR were investigated. Hydrophobicity recovery rate of SIR was evaluated by the measurement of contact angle. Arc resistance was evaluated by measuring weight loss of SIR after arc resistance test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.876-878
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• 2003

아크차단기(Arc-Fault Circuit Interrupter:AFCI)는 주택의 배선회로에서 아크가 발생하였을 경우 위험한 아크를 검출하여 차단하는 기능을 지니고 있다. 미국에서는 1993년부터 AFCI를 개발하기 시작하여 1997년 후반에 최초의 상압용 AFCI 제품을 출시하였다. 또한 UL(Underwriters Laboratories Inc.)에서는 1999년 2월에 AFCI에 대한 최초의 제품규격인 UL1699를 출간하였다[1-5]. 본 논문에서는 AFCI에 대한 유일한 시험규격인 UL1699를 정리해 보고, 특히 AFCI의 고유기능인 아크검출기능을 시험할 수 있는 시험항목과 AFCI의 분류별 시험항목을 분석하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.140-141
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• 2007

The arc ion plating (AIP) technique has been used widely for thin coating in the area of surface engineering. The TiN coating is important in the field of dies, cutting tools and other mechanical parts. When forming the TiN films by AIP technique, the processing parameters such as arc power, bias voltage, working pressure, temperature of substrate and pre-treatment affected the adhesion respectively. The results of scratch test revealed that the adhesion strength was influenced by arc power most strongly. And a sequence of the importance of each parameters has been obtained. The crystal structure and cross-section of TiN films are also be investigated.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.80-88
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• 2000

The plasma spray technics has known as one of the surface modification methods to improve the mechenical properties or the functional charactristics of materials. This paper has been aimed to investigate the effects of plasma sprayed conditions, such as spray distance and arc power level, on sliding wear properties of plasma sprayed $Al_2$O$_3$-40%TiO$_2$coating layer. The sliding wear test using pin-on-disc type wear machine, has been conducted in several sliding speed for coating layer sparyed under different conditions. The result of this paper is that the wear resistance of plasma sprayed $Al_2$O$_3$-40%TiO$_2$coating layer is fluctuated with tile spray distance and the arc power level. The wear resiatance could be improved with decreasing the spray distance and with increasing the arc power level.

• Journal of Welding and Joining
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• 제1권2호
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• pp.53-60
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• 1983

COD test based on fracture mechanics concept was used in this study to evaluate the fracture toughness quantitatively. Effects of specimen sizes on critical COD value for ABS EH 36 steel and its submerged arc weldments, and the variation of critical COD value depending on metallurgical/mechanical heterogeneities caused by weld thermal cycles were investigated. Experiment was performed by using specimens made from base metal and submerged arc weldments according to BS 5762. Obtained results are summarized as follows; 1) Critical COD value for base metal decreases with increasing thickness of specimen. On hand, as the reduction ratio of critical COD decreases with increasing specimen thickness, critical COD value becomes constant above a thickness of specimen. 2) Critical COD value for weldment decreases with increasing thickness of specimen and was also affected by metallurgical states of base metal. 3) Size effects for weldment was greater at the hardened region. 4) Critical COD value was affected by microstructural change due to weld thermal cycles in weldments; that is, accicular ferrite formation is favorable for increasing of COD value.

• 전력전자학회논문지
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• 제4권2호
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• pp.128-137
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• 1999

최근 전력전자기술 및 인버터 회로의 다양한 제어기법의 발달에 따라서 용접기 분야에서의 용접성능 향상에 관한 다양한 연구가 진행되고 있으며 특히{{{{ { CO}_{2 } }} 아크 용접기의 경우 용접성능을 좌우하는 스패터 발생을 최소화 하는 기법이 활발하게 연구되고 있다. 그러나 현재까지는 용접기의 출력전압을 정전압으로 제어하는 방식을 사용함에 따라 용접기의 금속이행과정을 임의로 제어하는 것이 불가능하였고, 특히 스패터가 다량으로 발생하는 저전류영역의 금속이행과정인 단락이행에서의 스패터 저감을 기대하기가 어려웠다. 따라서 본 논문에서는 마이크로프로세서를 이용한 인버터 출력전류의 파형제어기법을 사용하여 인버터 아크 용접기의 출력전류를 순시적으로 제어함에 의하여 스패터 저감, 단락주기의 안정화 및 순간단락현상 감소의 측면에서 용접성능을 개선위한 연구를 수행하였고 이상의 연구에 대한 결과를 제시하였고, 또한 인버터 아크 용접기의 AC/DC 전력변환장치로 SMR(Switched Mode Rectifier)를 사용하여 시스템을 단위역율로 운전하였으며 입력전류의 저차 고조파 억제효과를 얻을 수 있었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권6호
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• pp.273-284
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• 2002

In this paper, computer simulations of the physical Phenomena occurring in the arc region before and after current zero were carried out to evaluate the dielectric recovery characteristics of two types of double-flow nozzles. A commercial CFD Program "PHOENICS" is used for the simulation and the user-coded subroutines to consider the arcing phenomena were added to this program by the authors. The computed results were verified by the comparison with the test results presented by the research group of BBC. In order to investigate the state of the arc region after current zero, the simulation was carried out with four steps. They are cold gas flow analysis, steady state arc simulation, transient arc simulation before current zero, transient hot gas flow simulation after current zero. The semi-experimental arc radiation model is adapted to consider the radiation energy transport and Prandtl′s mixing length model is employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The streamer criterion was introduced to evaluate the dielectric recovery characteristics after current zero. Compared with the results obtained by assuming the current zero state in the former studies, it has been found that the results obtained by considering the state before current zerowere more accurate.

• 한국건설순환자원학회논문집
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• 제5권3호
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• pp.253-260
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• 2017

본 연구에서는 초고강도 콘크리트의 경제적인 제조 방안을 제시하기 위하여 국내에 유통되는 석회암골재와 전기로 산화슬래그를 잔골재로 조합사용하여 이들이 80MPa급 초고강도 콘크리트의 제반 물성에 미치는 영향을 실험적으로 고찰하고자 한다. 골재종류로서 화강암 굵은골재, 석회암 굵은골재 조합에 잔골재로서 석회암, 화강암을 사용하였고, 추가적으로 석회암 잔골재에 전기로 산화슬래그 잔골재를 25% 및 50% 치환한 조합으로 골재를 선정하였다. 연구결과에 따르면, 석회암 잔굵은골재를 사용한 경우와 여기에 전기로 산화슬래그 잔골재를 치환한 경우 설계된 고성능 감수제량으로도 목표 슬럼프플로를 만족하였으나, 화강암골재를 사용한 경우 목표값을 만족시키지 못해 고성능 감수제량을 증가시켜주어야 할 것으로 판단된다. 압축강도의 경우 석회암골재의 높은 탄성계수에 기인하여 화강암 골재를 사용한 경우보다 높은 콘크리트 압축강도를 발휘하였고, 전기로 산화슬래그를 치환한 경우 28일이후 강도가 다소 저하하는 것으로 나타났다. 자기수축은 석회암잔골재에 전기로 산화슬래그잔골재를 치환한 경우 자기수축을 9~25%정도 저감시킬 수 있는 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제36권4호
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.