• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.804-808
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• 2010

In this paper, we studied the dielectric breakdown voltage characteristics by the AC withstand voltage test on using green insulation dry air instead of $SF_6$ insulation gas used in the GIB (gas insulated bus) of 362 kV GIS (gas insulated switchgear). The AC withstand voltage test applied to the standard KEPCO's 362 kV GIB with dry air insulation, and the equivalence of dielectric breakdown voltage for dry air and $SF_6$ gas were examined, and the empirical formulas of dielectric breakdown voltage for dry air were calculated, and the criterion of AC withstand voltage test for dry air insulation was derived. Using the criterion, dry air can be used instead of $SF_6$ gas for 362 kV GIB in the factory acceptance test was confirmed.

• 한국정보전자통신기술학회논문지
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• 제9권6호
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• pp.534-538
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• 2016

This paper discusses the characteristics and effects of dielectric inner-supports on discone antenna for broadband RF test chamber, and the verification has been performed by simulation. Several design parameters such as the thickness of the gap support, the position of the side support, and the thickness of the side support has been analyzed. The thickness of the gap support affected the reflection coefficient. An effect of the offset of the side support from the center was slight below 3 GHz and significant above 3 GHz. The thickness of the side support did not affect the reflection coefficient or the gain much. The performance of the fabricated discone antenna was in good agreement with the simulated results. This investigation of a dielectric support effects could be used to design a commercial discone antenna for broadband RF test chamber, focusing on electrical performance and mechanical stability.

• 한국전자파학회논문지
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• 제18권5호
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• pp.471-477
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• 2007

본 논문은 전자파 장해 및 복사 내성 측정의 대용 시험 시설로서 활용될 수 있는, 다중 유전체로 구성된 평탄형 QRD(Quadratic Residue Diffuser)를 사용한 전자파 잔향실에 대한 연구이다. 잔향실은 $2.5{\sim}3$ GHz 대역에서 사용 가능하도록 설계되었으며, 기존 QRD의 특성을, 다양한 유전체를 이용하여 낮은 평탄형 구조물로 구현하였고, 이를 적용한 전자파 잔향실 내부에서의 전자기장 특성 변화 및 시험 공간 확장에 관해서 비교 분석하였다. 잔향실 내부의 전자기장 분포 해석을 위해서 FDTD(Finite-Difference Time-Domain) 수치 해석 방식을 이용하였다. 잔향실 내에 새로 제안된 확산기를 사용하면, 기존 확산기에 비해 물리적인 크기가 줄어들 뿐만 아니라 전자기장 균일도, 편파 특성 및 공차 등의 성능이 비슷하거나 우수해짐을 확인하였다. 따라서 다중 유전체로 구성된 평탄형 확산기를 사용한 잔향실이 기존의 QRD를 사용한 잔향실에 비해 전자기적 성능 및 공간 활용면에서 우수한 시험시설임을 확인하였다.

• 정보저장시스템학회논문집
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• 제4권1호
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• pp.13-18
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• 2008

Scratches are observed on a polymer cover-layer of near-field recording (NFR) media after a servo test with rotating disc. The scratches are formed by the collision of a solid immersion lens (SIL)-media. One of the possible ways to avoid the scratch problem is to coat a dielectric protective film on the polymer cover-layer which enhances the hardness of the surface. The surface with hard characteristics in the surface reduces the scratch problem in the cover-layer. Not only the mechanical properties but also the optical properties should be controlled. Specifically, the refractive index of the dielectric protective film should be matched with the polymer cover-layer not to lose light at the interface due to the difference of the refractive index. The refractive index of the dielectric film can be tailored by controlling process parameters during sputtering and matched with that of the polymer cover-layer.

• 한국전기전자재료학회논문지
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• 제21권1호
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• pp.53-56
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• 2008

The commercial parallel plate electrodes system with guard-ring electrode have been widely used for measurement of dielectric constants of solid materials. And the specification of the electrodes system is about 1 % of measurement uncertainty. This measurement uncertainty is only estimated the error come from mechanical measurements such as the area of the electrodes and the gap between the electrodes except the error come from the air gap between the electrodes and dielectric specimen. Because it is impossible to measure the air gap. This study analyze the total measurement uncertainties of the commercial dielectric constant test cell using 3 kinds of Standard Reference Materials. As a results, the total measurement uncertainty is much bigger than 1 % and the most of the uncertainty can be reduced by compensation of the error values evaluated in this study.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.144-147
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• 2003

Cu+ ions drift diffusion in formal oxide film and SiOCH film for interlayer dielectric is evaluated. The diffusion is investigated by measuring shift in the flatband voltage of capacitance/voltage measurements on Cu gate capacitors after bias temperature stressing. At a field of 0.2MV/cm and temperature $200^{\circ}C,\;300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C$ for 10min, 30min, 60min. The Cu+ ions drift rate of $SiOCH(k=2.85{\pm}0.03)$ film is considerable lower than termal oxide. As a result of the experiment, SiOCH film is higher than Thermal oxide film for Cu+ drift diffusion resistance. The important conclusion is that SiOCH film will solve a causing reliability problems aganist Cu+ drift diffuion in dielectric materials.

• Composites Research
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• 제14권1호
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• pp.30-38
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• 2001

복합재료는 우수한 비강성, 비강도 특성 때문에 기존의 항공우주산업뿐만 아니라 로봇 팔. 공작기계 등에 널리 사용되고 있다. 복합재료 경화중의 온라인 모니터링기법은 생산성 향상 및 품질의 신뢰성 향상을 위하여 매우 중요한 연구분야로 대두되고 있다. 본 논문에서는 휘스톤 브리지식 유전회로를 설계하고 제작하였다. 또한 고온 경화 복합재료에 적용할 수 있는 고온 유전센서를 개발하여 그 성능을 평가하였다. 유한요소해석을 이용하여 유전 센서에 작용하는 열 잔류응력을 계산하였으며, 고온분위기 하에서 유전센서의 유전특성을 평가하였다. 이상에서 개발된 유전회로와 고온 유전센서를 이용하여 BMI(Blsmaleimlde) 수지의 경화모니터링을 수행하였다.

• Advances in materials Research
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• 제1권1호
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• pp.93-107
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• 2012

Epoxy resin is widely used in high voltage apparatus as insulation. Fillers are often added to epoxy resin to enhance its mechanical, thermal and chemical properties. The addition of fillers can deteriorate electrical performance. With the new development in nanotechnology, it has been widely anticipated that the combination of nanoparticles with traditional resin systems may create nanocomposite materials with enhanced electrical, thermal and mechanical properties. In the present paper we have carried out a comparative study on dielectric properties, space charge and dielectric breakdown behavior of epoxy resin/nanocomposites with nano-fillers of $SiO_2$ and $Al_2O_3$. The epoxy resin (LY556), commonly used in power apparatus was used to investigate the dielectric behavior of epoxy resin/nanocomposites with different filler concentrations. The epoxy resin/nanocomposite thin film samples were prepared and tests were carried out to measure their dielectric permittivity and tan delta value in a frequency range of 1 Hz - 1 MHz. The space charge behaviors were also observed by using the pulse electroacoustic (PEA) technique. In addition, traditional epoxy resin/microcomposites were also prepared and tested and the test results were compared with those obtained from epoxy resin/nanocomposites.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권2호
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• pp.103-108
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• 2004

This paper shows the simulation of electric field distribution and removal characteristics of Escherichia coli for water discharge tube with globular $SiO_2$. At the experiments of the removing Escherichia coli used the discharge tube with globular dielectric($SiO_2$), because the electric field is increased when applied voltage is increased, the removed ratio of Escherichia coli was related with increasing of applied voltage. When a passing number of test water in water discharge tube is increased, the removed ratio of Escherichia coli is increased because passing number of territory with electric field is increased. When diameter of globular dielectric($SiO_2$) is increased, the removed time of Escherichia coli was decreased because electric field for dielectric polarization of globular dielectric($SiO_2$) was increased. Also, the removed ratio of Escherichia coli of the water discharge tube with globular dielectric($SiO_2$) was measured higher than the removal ratio of the discharge tube without globular dielectric($SiO_2$)

• Tribology and Lubricants
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• 제24권2호
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• pp.82-89
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• 2008

The purpose of this study is to develop the proto type sensor installed inside an oil filter in order to detect oil deterioration level. The sensor is made up with two concentric cylinders with constant gap in between and a filter element inside the central area. The size will be designed as similar as real oil filters. The sensor will be tested on a test rig, which is circulating engine oil, with the same size of an oil filter adapting housing as real engines'. It will be measured the capacitance of a sample engine oil, then be able to be gotten the dielectric constant. The changes in the dielectric constant could be correlated with the engine oil deterioration level if the sensor development would be completed. In this paper, it will be shown the test results carrying out under variable temperature conditions at atmosphere pressure.