• 조명전기설비학회논문지
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• 제25권6호
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• pp.108-114
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• 2011

In order to mitigate the possible hazards from electric shock due to the touch and step voltages, the high resistivity material such as gravel is often spread on the earth's surface in substations. When the grounding electrode is installed in two-layer soil structures, the surface layer soil resistivity is different with the resistivity of the soil contacted with the grounding electrodes. The design of large-sized grounding systems is fundamentally based on assuring safety from dangerous voltages within a grounding grid area. The performance of the grounding system is evaluated by tolerable touch and step voltages. Since the floor surface conditions near equipment to be grounded are changed after a grounding system has been constructed, it may be difficult to determine the tolerable touch and step voltage criteria. In this paper, to propose an accurate and convenient method for evaluating the protective performance of grounding systems, the propriety of the method for evaluating the current flowing through the human body around on a counterpoise buried in two-layer soils is presented. As a result, it is reasonable that the grounding system performance would be evaluated by measuring and analyzing the current flowing through the human body based on dangerous voltages such as the touch or step voltages and the contact resistance between the ground surface and feet.

• 조명전기설비학회논문지
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• 제23권2호
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• pp.154-160
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• 2009

본 논문은 친환경 절연재료인 Dry-Air 중 에폭시 수지의 연면절연특성을 구명하여 Dry-Air를 절연매체로 사용한 각종 절연설계 시에 응용 가능한 기초자료를 제공하고자 한다. 사용한 전극은 침 대 평판, 구 대 평판, KS M3015 전극으로써, 동일한 조건 하에서 전극의 종류에 따른 연면 절연 파괴 전압, 연면 거리, 연면방전 전계강도를 비교하였다. 연면전계강도는 침 대 평판 전극 하에서 가장 높게 나타났다. 또한 에폭시 수지의 두께와 지름을 변화시켰을 때의 연면 절연 특성은 에폭시 수지의 두께가 두꺼울수록, 지름이 길수록 연면 절연 파괴 전압이 높게 나타남을 확인하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.337-340
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• 2008

When high surge voltage invaded into the ground rod contacted with ground water, the ionization phenomena are happened in the water. Although some researchers have surveyed the ionization phenomena in soil, they have just analyzed the variation of the ground resistance. The most important role of the ground rod is to elect human beings from potential rise and to dissipate energy to the earth safely. In this wort we presented the method evaluating the potential reduction and energy dispersion. Also we analyzed theses factors as a function of charging voltages at the water resistivity of $50\;{\Omega}{\cdot}m$ using the Matlab Program. As a result the ground rod potential was reduced to 38 kV by ionization just below breakdown voltage. The energy more than half of the total injected energy was dispersed through the grounding electrode caused due to ionization.

• 조명전기설비학회논문지
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• 제15권3호
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• pp.51-56
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• 2001

본 논문에서는 침대평판 전극구조를 구성하여 침전극에 직류 정 ·부 고전압을 인가한 경우 전계와 자계가 직각방향으로 형성되도록 하고 자계가 코로나 방전현상에 미치는 영향을 측정하고 분석하였다. 정의 고전압을 인가한 경우 자계인가에 의해 방전코로나 영역이 확장되고 이때 흐르는 코로나전류가 감소하였고, 절연파괴전압은 증가되었다. 그러나 부의 고전압을 인가한 경우는 방전코로나 영역이 오히려 축소되고 흐르는 전류가 증가되었으며 절연파괴전압은 감소되었다. 이는 전자계가 동시에 존재하는 영역에서 코로나방전에 의해 생성된 전하들의 로렌쯔력에 의한 싸이크로트론 운동 때문인 것으로 생각된다.

• 조명전기설비학회논문지
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• 제17권4호
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• pp.50-56
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• 2003

본 논문에서는 유입변압기 진단을 목적으로 부분방전시 발생하는 여러 가지 물리적 화학적 현상중 초음파를 검출하기 위하여 광섬유 Mach-Zehnder 간섭계를 구성하였다. 구성된 광섬유 센서의 초음파 검출 평가 실험을 실시하고, 절연유 중에 배치한 침-평판전극에 교류 고전압을 인가하여 방전시 발생하는 초음파를 측정하고 퓨리에 변환 및 wavelet 변환을 이용한 데이터 분석 결과를 나타냈다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.31-34
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• 2006

The characteristic of carbon nano fiber (CNF) as electron emitters was described. Carbon nano fiber (CNF) of herringbone was prepared by thermal chemical vapor deposition(CVD), mixed with binders and conductive materials, and then were formed by screen-printing process. In order to increase effectively field emissions, the surface treatment of rubbing & peel-off was applied to the printed CNF emitters on cathode electrode. The measurements of field emission properties were carried out by using a diode structure inline vacuum chamber. CNF of herringbone type showed good emission properties that a turn on field was as low as $2.5V/{\mu}m$ and current density was as large as $0.15mA/cm^2$ of $4.5V/{\mu}m$ with electric field. After the vacuum packaged panel of 5-inch in diagonal, the measured white brightness was as high as $7000cd/m^2$ at 1900V of anode and 700V of gate voltage.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.54-58
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• 2006

본 논문에서는 공동주택에 적합한 인하도선시스템과 접지시스템 설계를 위한 기본적 사항에 대하여 고찰하였다. 공동주택의 철근구조체는 전기적 연속성을 갖지만 철근들끼리의 결속선에 의한 접속은 전자기계력에 대한 내력이 부족하다. 따라서 전용의 인하도선을 설치하고 이들을 건물 양 측벽의 철근구조체와 본딩하여 낙뢰전류가 인하도선 및 철근구조체에 분산되어 흐르게 하는 인하도선시스템을 제시하였다. 한편 공동주택의 접지시스템은 건물기초접지극과 피뢰설비를 위한 환형 접지극으로 각각 구성하고 이들을 서로 본딩하는 접지시스템을 제시하였다. 또한 공동주택 각동의 건물기초접지극을 공동구의 철근구조체나 접지선을 이용하여 서로 연결함으로서 공동주택 단지에 거대한 총괄접지시스템을 구현하는 방안을 제시하였다. 하지만 이러한 피뢰시스템을 구축하기 위해서는 완벽한 본딩시스템의 구축이 전제되어야 한다.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.98-105
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• 2014

Soil discharges near the ground rod play an important role to reduce the ground potential rise and the ground impedance and to help the fault current to spread into the earth. This paper presents the effects of soil discharges on the transient and conventional ground impedances when the lightning impulse voltage was applied to a ground rod with radial needles. The current-voltage (I-V)curves and transient ground impedance curves were calculated based on the measured current and potential traces. Soil discharge behaviors related to I-V curves and transient ground impedance curves were analyzed as a function of the magnitude of lightning impulse voltages. As a result, the soil discharges occurred near the ground electrode contribute to the reduction of conventional ground impedance and limits the ground potential rise effectively under lightning impulse voltages.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.76-81
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• 2014

The ozone generation is commonly made with silent discharge method using quartz glass dielectric. In this paper, using $Al_2O_3$ dielectric to instead of the traditional quartz glass dielectric to improve the system efficiency is presented. The dielectric was manufactured as tube shape (Internal diameter${\times}$ Outside diameter: $11{\times}15mm$) using 99% $Al_2O_3$ ceramic. The characteristics of dielectric discharge and ozone generation were studied of experiments with variation of discharge power, discharge electrode space and rate of flow for supplied gas ($O_2$/Air). As the experimental results, in the same discharge space, the ozone concentration continuously increased with input power increasing, and ozone yield increased until saturation happened. Also, the expended power increased with discharge space extended due to discharge power increased. In additional, the ozone concentration of oxygen ozone was higher than air that was observed when using oxygen ozone in proposed experiments.

• 조명전기설비학회논문지
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• 제30권1호
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• pp.1-7
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• 2016

With a collimated $CO_2$ laser beam, the bidirectional current switching was realized in a two-terminal electronic device based on a highly resistive vanadium dioxide($VO_2$) thin film. A $VO_2$ thin film was grown on a $Al_2O_3$ substrate by a pulsed laser deposition method. For the fabrication of a two-terminal electronic device, the $VO_2$ thin film was etched by an ion beam-assisted milling method, and the $VO_2$ device, of which $VO_2$ patch width and electrode separation were 50 and $100{\mu}m$, respectively, was fabricated through a photolithographic method. A bias voltage range for stable bidirectional current switching was found by using the current-voltage property of the device measured in a current-controlled mode. The transient responses of bidirectionally switched currents were analyzed when the laser was modulated at a variety of pulse widths and repetition rates. A switching contrast was measured as ~3333, and rising and falling times were measured as ~39 and ~21ms, respectively.