• 전기학회논문지
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• 제57권11호
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• pp.2011-2014
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• 2008

We measured the permittivity and electromagnetic wave propagation velocity of used insulation oil with wide frequency range including ultra-high frequency by time domain reflectometry. The permittivity or propagation velocity is essential for locating discharge faults of oil filled power transformer. We derived 2.21 as a permittivity and $2.03{\times}10^8 m/s$ as a velocity from the measurement of pulse travelling time along a coaxial line filled with used insulation oil or air. The permittivity measurement system we designed shows high measurement accuracy and the convenience for field use.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.267-270
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• 2000

This paper describes measurement of relative permittivity of illite found in young-dong area. A measurement of relative permittivity of illite used to cylindrical cavity resonators with moveable cap. A concentric dielectric-rod inserted cylindrical cavity resonator and an exact field representation of travelling wave mode are introduced for measurement of relative permittivity. The exact electromagnetic fields in cylindrical cavity with concentric dielectric rod is analysed. A relative permittivity of dielectric in cavity is calculated by analyzing the characteristic equation. The characteristic equation is solved by using the ContourPlot graph of Mathematica. We know that the field representation of travelling mode is exact. As a result, relative permittivity of dielectric materials were 7.820 at sample-1 and 7.894 at sample-2.

• 콘크리트학회논문집
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• 제12권3호
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• pp.115-123
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• 2000

Characterizing the electromagnetic properties of concrete is essential to the enhancement of accuracy and reliability in nondestructive testing of concrete structures using electromagnetic techniques. To establish a data base for the properties of concrete, a measurement technique has been developed and a set of data has been obtained for the frequency range of 1~6 GHz. As moisture content is one of major contributing factors to determine permittivity of dielectric material, moisture content is varied during the measurement. An application of a measurement system which consists of open-ended coaxial probe and automatic network analyzer to concrete and mortar specimens is studied. For this, calibration techniques, size of specimens, and number of measurements necessary to obtain reliable data are investigated. From the measured data, it is shown that moisture content plays an important role to determine the permittivity of specimens. As the moisture content increases. The permittivity of specimens show tendency to approach the permittivity of water.

• Tribology and Lubricants
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• 제27권4호
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• pp.209-212
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• 2011

The capacitive application(prove) can be used to measure the complex permittivity of dielectric material of various thickness and cross section. This paper presents that we designed the analysis system of engine oil permittivity to know the relation between the engine oil deterioration and the prove dimension. Each of the dimension of capacitive prove is changed and then electric capacity is measured by LCR {Inductance(L), Capacitance (C), and Resistance (R)} meter. The engine oil permittivity has extracted in the prove measurement. As the additional research, this paper suggest the best of the prove dimension for the permittivity measurement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.779-784
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• 1998

The velocity and amplitude of microwaves are affected by the electromagnetic properties of a material through which the wave propagates. And the electromagnetic properties of a dielectric material such as concrete is represented by its permittivity. For the development of an accurate and reliable nondestructive testing (NDT) technique for concrete structures using microwave, it is necessary to have knowledge about the permittivity of concrete. In this paper, mortar specimens are used to serve as a basis for further measurement of concrete. The effect of water on the permittivity was studied using specimens with different water content. To assure the reliability of the measurement results, a statistical method was introduced.

• 전기학회논문지
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• 제56권12호
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• pp.2196-2201
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• 2007

Materials used at microwave are usually used as a dielectric with a manufacturing purpose of printed circuit boards, etc. Complex permittivity of them can be measured from attenuation constant or propagation constant of a transmission line using a microstrip line with bulk type. But as the technique recently which can manufacture to have complex permittivity and permeability demanded using nonferrous metals for powder-type grows up, we need sensors and methods which can measure characteristics of powder-type materials. So far measuring methods of permittivity and permeability with waveguide or coaxial cable are used but they have faults which have a complex measurement method and are difficult to simultaneously measure permittivity and permeability. In this paper, a simultaneous measuring method of permittivity and permeability with 2-port coaxial cable and a new proposed calculation. The proposed 2-port coaxial cable is designed to be easy to insert materials and to have a wideband. We measure permittivity and permeability of magnetic powder(Ni-Fe-Mo, Ni-Fe) which reveal its characteristic at $0.3{\sim}1.3GHz$ to identify the proposed sensor.

• 한국인터넷방송통신학회논문지
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• 제12권2호
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• pp.199-203
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• 2012

평행판 도파관에 진행하는 TEM mode를 이용한 평판형 유전체의 유전율을 측정하는 방식을 소개한다. 이는 양 옆이 열린 구조적 장점으로 실험 절차 및 측정 샘플의 가공이 매우 간편한 장점이 있다. 샘플의 유무에 따라 변화하는 도파관 내에서 전파하는 TEM mode의 위상 속도의 차이를 전자기적으로 해석하였고 이를 이용하여 유전체판의 유전율을 측정하였으며, 샘플에 대한 측정 결과는 기존에 알려진 유전율과 일치하였다.

• Tribology and Lubricants
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• 제27권3호
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• pp.156-161
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• 2011

The rectangular waveguide technique can be used to measure the complex permittivity of dielectric material of various thickness and cross section. This paper presents the analysis system of engine oil permittivity at which deterioration of engine oil is measured at the X-band(8-12.5 GHz). The middle of the rectangular waveguide has engine oil case and is connected with VNA(Vector Network Analyzer) for the measurement of the transmission$(S_{21})$ and reflection$(S_11)$ and then the permittivity is extracted. The deterioration of engine oil is proved by the comparison with both the extracted data and reference data. As the additional research, This paper suggest that an accurate permittivity is considered by not only the wave guide length but the air gap between oil case and the waveguide.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.268-272
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• 2014

This letter presents a measurement methodology of the complex permittivity of liquid using a partially open cavity in narrow band. The partially open cavity (POC) can measure dielectric small changes caused by the temperature variation of the liquid inside the cavity as well. Using the resonance frequency and unloaded quality factor of the proposed POC, the complex permittivity is evaluated. The apertures on the walls of the cavity are designed to circulate the liquid inside to outside of the POC and located at the corner area of the cavity to minimize the disturbance of field distribution at the dominant mode. The results measured by the proposed POC were compared with those by the conventional open-ended probe and Cole-Cole equation. The POC showed better performance in measuring small dielectric constant changes than the open-ended probe.

• 한국전자파학회논문지
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• 제12권5호
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• pp.747-754
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• 2001

영동산 일라이트의 비유전율 측정에 대해 기술한다. 비유전율을 측정하기 위해 윗면 조정이 가능한 원통형 공동 공진기가 이용되었다. 동심 유전체 봉이 삽입된 원통형 공동 공진기를 이용하는 방법과 non-decaying 모드의 정확한 전자계 표현은 비유전율을 측정하기 위해 소개되었다. 동심 유전체 봉이 삽입된 경우에 정확한 전자계 표현들을 해석하였다. 유전체가 삽입된 공진기를 이용한 비유전율의 계산은 특성방정식의 해석에 의해 계산된다. 특성방정식은 상용 수학 툴인 Mathematica의 ContourPlot 그래프 기능을 이용하여 풀이하였다. Non-decaying 모드 해석법은 근사적인 해석법이 아니라, 정확한 해석법이다. 결과적으로 바인더가 들어있는 유전체 시료에 대해서는 7.820의 비유전율이 측정되었고, 바인더가 없는 유전체 시료에 대해서는 7.894의 비유전율이 측정되었다.