• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.217-226
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• 2001

A small sized ceramic dielectric patch antenna is designed and implemented for GPS/GLONASS combined receiver, and it shows a wideband characteristics with circular polarization. For the miniaturization of the antenna, high-permittivity dielectric material is used, and the wideband characteristics with low axial-ratio is achieved by using dual feed with 90$^{\circ}$ phase difference. The measured data of the manufactured antenna show that the bandwidth is 242 MHz, the axial ratio is less than 3 dB, the half-power beam-width is more than 112$^{\circ}$, and the antenna satisfies the required characteristics of the GPS/GLONASS antenna.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.286-289
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• 2018

This paper tests the feasibility of using the transparent electrode as the electrode of the capacitor in order to use the vehicle glass of the electric vehicle for a capacitive coupling wireless transfer (CCWPT). Large coupling capacitance can be obtained due to large area and high permittivity using the glasses of an electric vehicle. However, if an electrode is formed on a metal such as copper, then a view cannot be guaranteed and a transparent electrode can pose a solution. Therefore, the coupling capacitor is implemented by forming a glass dielectric with an ITO transparent electrode on one side through a semiconductor deposition process. The loss of the coupling capacitor is investigated, and a 200 W CCWPT prototype is fabricated and tested for its characteristics and power transfer.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2061_2062
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• 2009

Within serviced period of time in transformer, thermal stress is the most influential parameter affecting the aging behavior of an insulation system. The thermal stress on the insulation system may occur from operation in a high temperature environment due to Joule's heat at winding coils. This paper describes a development of capacitive sensor and preventive diagnosis techniques for electrical insulating oil, widely used for power and distribution transformer. To survey the dielectric properties of the virgin and used mineral insulating oil, we utilized the highly precise measuring system of KRISS. And the results were used to determine the design factors of the sensor. To evaluate diagnosis by the sensor, we performed accelerated aging test about insulating oils. The condition of aged specimens were investigated by measurements of relative permittivity i.e. capacitance change by capacitive sensor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1840-1847
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• 2016

The surface of nanosilica and microsilica was modified in order to develop a high voltage insulation material for outdoor application. The modified silicas were well dispersed in an aliphatic cyclic epoxy resin. Dielectric properties were studied for 8 kinds of specimens: 1 kind of neat epoxy, 3 kinds of epoxy/microsilica composites, and 4 kinds of epoxy/microsilica/nanosilica composites. Complex dielectric constants were measured in the range of 10-2~1.2 Hz at room temperature.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.35-35
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• 2003

In satellite communication, attenuation, scattering, and depolarization of relatively high frequency waves such as millimeter waves are strongly influenced by rain. In order to study the rain attenuation, we introduce a new theoretical method, which enables us to obtain the reflection and transmission coefficients in arbitrary medium. We adopt this method to examine how the electromagnetic radiation is affected by homogeneous spherical raindrops. It is assumed that the raindrop shape is spherical and linearly locate in one direction. For the radiation of wave in raindrops, we consider the effective permittivity, in which the raindrop is assumed to be spherical. By adopting the invariant imbedding approach, the 1st order differential equations are derived for the reflection and transmission coefficients. We investigate the transmission and reflection of waves for various incident angles when the spherical raindrops are assumed to have random sizes.

• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.113-118
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• 2002

In this paper, an internal GPS antenna for mobile phones is designed and fabricated. For the miniaturization of the antenna, high permittivity dielectric substrate((${\varepsilon}_r$=90) and small ground plane ($13mm{\times}13mm$) are used. To increase the receive gain, the antenna is composed with LNA(Low Noise Amplifier). Results of the manufactured antenna($13mm{\times}13mm{\times}8mm$) show that the maximum antenna gain is about 12 dBi, the axial ratio is less than 3 dB, and the current consumption of LNA is less than 4 mA.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.139-142
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• 2007

본 논문은 RFID(Radio frequency identification) 수동 태그 안테나의 설계 시 고려 할 사항에 대한 연구이다. 일반적으로 RFID 태그 안테나는 몇 가지의 기본적인 사용 용도에 따라 안테나가 최적화 되어있다. 최근에는 그 용도가 다양화 되고 특수한 용도로 사용되는 경우가 빈번하나 이에 대한 기본적인 연구가 미비하였다. 본 연구에서는 상용화 된 태그 안테나를 사용하여 도자기 표면에서의 안테나 특성 변화를 살펴보았고 이를 통해 좀 더 다양한 태그 안테나의 설계와 튜닝 방법에 대해 논의 하고자 한다.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.208-213
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• 1994

Wide-band absorbency and small layer thickness are required in the high- performance microwave absorber. In order to reduce the thickness of the absorber, ferrite-iron-rubber composites were proposed and its properties were investigated. The increase in both real part of perrreability and permittivity of the composites were observed with addition of -Fe powder and this behavior results in the decrease of fm dm term. The matching thicknesses of ferrite-iron-ruber composites were relatively small(0.5~2.0 mm) in the frequency range of 3~17 GHz as comIBfed to than that of ferrite-rubbr composit.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.1
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• pp.16-22
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• 2003

This paper presents an application of an impedance boundary condition to 3D vector finite element analysis of a multi-port cylidrical microwave cavity using Snell's law. Computing memory benefits and computing time reduction are obtained from this method compared with the conventional finite element method(FEM). To verify the method, a high permittivity scatterer in free space is analyzed and compared with the results of conventional (FEM). In addition, this method has been analyzed several types of cavities, including water load, to demonstrate the validity and accuracy of the program.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1098-1101
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• 2003

Complex impedances with frequency and voltage variation were analyzed in ITO/$Alq_3$/Al device structure at thickness 100 nm and 200 nm of $Alq_3$, respectively. At low frequency, complex impedance is mostly expressed by resistive component, and at the high frequency by capacitive component. Also, we have evaluated resistance, capacitance and permittivity.