• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.416-418
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• 2000

Thin films of phase-pure perovskite $(Pb_{0.72}La_{0.28})Ti_{0.93}O_3$ (PLT) were deposited in-situ onto Pt/Ti/$SiO_2$/Si substrates by pulsed laser deposition. We have systematically investigated the variation of grain sizes depending on the process condition. Both in-situ annealing and ex-situ annealing treatments have been compared depending on the annealing time. The grain sizes of PLT thin films were successfully controlled 260 to 350 nm by changing process parameters. Microstructural and electrical properties of the film were investigated by C-V measurement, leakage current measurement and SEM. Two-step process to grow $(Pb_{0.72}La_{0.28})Ti_{0.93}O_3$ (PLT) films was adopted and verified to be useful to enlarge the grain size of the film and to enhance the leakage current characteristics.

• 한국세라믹학회지
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• 제29권10호
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• pp.779-784
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• 1992

In producing cordierite glass-ceramics by sintering, following experiments were conducted in order to determine the optimum heat-treatment schedule for high-crystallinity and dense sintered body. The glass composition of 11.67MgO-29.46Al2O3-52.88SiO2-5P2O5-1B2O3 (wt%) was selected on the basis of the early experiment. The 3-step heat treatment schedule was determined by the results of DTA, Dilatometric measurement and high-temperature XRD, where the particle-size-controlled glass powder was used. The degree of densification and the crystallinity were evaluated by the measurement of the bulk density and X-ray scattering intensity. The specimen fired with the optimum conditions showed ${\alpha}$-cordierite phase, relative density ∼98%, crystallinity ∼92%, thermal expansion coefficient ∼30${\times}$10-7/$^{\circ}C$, dielectric constant ∼5.5 and resistivity ∼1.0${\times}$1012 {{{{ OMEGA }}cm, respectively.

• 전자공학회논문지A
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• 제30A권4호
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• pp.11-19
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• 1993

The complex permittivity and the linewidth of microwave ferrites are measured using the well known cavity perturbation method. The cavity perturbation method has been widely used for the measurement of complex permittivity and conductivity of low loss magnetic and dielectric materials at microwave frequencies. TT1-2000, TT73-2200, and G-113 samples ordered from Trans-Tech Inc, are tested. TE$_{103}$ and TE$_{106}$ rectangular waveguide cavities are fabricated and the ferrite sample of cylidrical rod and sphere shapes are prepared. The error between the measurement values and the supplier's data is less than 1 percent in case of $\varepsilon$’ and about 10 percent in case of linewidth ($\Delta$H). Worst case error analysis shows that our measured results are well within the error bound calculated from the accuracy specification of the measuring instruments.

• 한국전기전자재료학회논문지
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• 제31권7호
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• pp.469-474
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• 2018

In this study, the capacity and FTIR of polycarbonate film that was degraded for 2, 4, and 8 h in a thermostat at $180^{\circ}C$ was measured. The results of this study are as follows. It was found that the capacity decreased with increasing degradation time and frequency. This findings suggest that the attraction between molecules and amorphous polycarbonate increased because it contains the ketone group (-C=O-) and the chain of dioxides group (-O-R-O-). Measurement by FTIR found that the time of thermal degradation has a smaller impact because the transmutation or variation of the material does not occur. Measurement by SEM magnified 1,000 times found that a longer thermal degradation time results in thermal decomposition of the specimen's particles.

• 한국전기전자재료학회논문지
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• 제13권5호
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• pp.396-401
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• 2000

In order to accurately measure the high voltage of 22.9[kV] power distribution lines we investigated the temperature dependence of measuring voltage on the number of stack layers in the voltage measurement system made from single and stack voltage divider capacitors (22, 44, 66 layers, respectively). Temperature coefficient of dielectric constant(TC$\varepsilon_{{\gamma}}$/)of voltage divider capacitors which were fabricated by BaTi $O_3$system ceramics showed the variations from -2.28% to +1.69% in the range of -25[$^{\circ}C$] ~50[$^{\circ}C$]) was decreased with increasing of stack number and the stack element of 66 layers showed the least error of $\pm$0.87%or of $\pm$0.87%.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권2호
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• pp.63-68
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• 2005

Total 12 units of high power klystron-modulator systems as microwave source are under operation for 2.5 GeV electron linear accelerator in Pohang Light Source (PLS) linac. The klystron-modulator system has an important role for the stable operation to improve an availability statistics of overall system performance of klystron-modulator system. RF power and beam power of klystron are precisely measured for the effective control of electron beam. A precise measurement and measurement equipment with good response characteristics are demanded for this. Input power of klystron is calculated from the applied voltage and the current on its cathode. Tiny measurement error severely effects RF output power value of klystron. Therefore, special care is needed to measure precise beam voltage. Capacitive voltage divider (CVD), which divides input voltage as capacitance ratio, is intended for the measurement of a beam voltage of 400 kV generated from the klystron-modulator system. Main parameter to determine standard capacitance in the high arm of CVD is dielectric constant of insulation oil. Therefore CVD should be designed to have a minimum capacitance variation due to voltage, frequency and temperature in the measurement range. This paper will be present and discuss the design concept and analysis of capacitive voltage divider for a pulsed high-voltage measurement, and the empirical relations between capacitance effects and oil temperature variation.

• 한국전자파학회논문지
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• 제25권8호
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• pp.872-878
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• 2014

본 논문은 새로운 캐비티 공진기 구조를 이용한 반고체 상태 물질의 복소 비유전율 측정 방법을 제안하고 있다. 윗면에 개구면이 존재하고, Ground 판이 분리되어 있는 구조를 이용하여 반고체 상태 물질도 캐비티 내부에 위치할 수 있도록 했다. 공진주파수의 변화와 Critical-Points Method를 이용해 실험적으로 증류수와 0.9 % 식염수의 복소 비유전율을 측정하였으며, 측정값을 Cole-Cole Equation을 통해 이론값과 비교했다.

• 한국전자파학회논문지
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• 제27권3호
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• pp.246-252
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• 2016

본 논문에서는 유전체 장벽 방전(dielectric barrier discharge: DBD) 플라즈마에 의한 monostatic RCS 감소 특성을 측정하였다. Monostatic 레이다 단면적(radar cross section: RCS) 교정을 위하여 서로 다른 크기의 금속 평판을 사용하여 산란계수(scattering parameter)를 측정하였고, 그 결과 0.4 dB 이내의 오차를 보였다. DBD 플라즈마에 의한 monostatic RCS 감소 특성을 측정하기 위해 DBD 플라즈마 발생기 뒤에 금속 평판을 배치하였다. 금속 평판과 플라즈마 발생기 사이에 아크 방전(arc dischrage)이 일어나는 것을 방지하기 위해 금속 평판과 DBD 플라즈마 사이의 간격을 띄워 측정을 진행하였다. 그 결과 7.4 GHz에서 monostatic RCS가 최대 약 3 dB 감소하였다.

• Journal of the Korean Wood Science and Technology
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• 제45권5호
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• pp.629-639
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• 2017

현재 합천 해인사에 보관되어 있는 고려속장경(일명 팔만대장경)은 역사적 가치나 규모면에 있어서 세계적인 문화재이나 아직도 어떤 수종으로 만들어졌는지 모르고 있다. 중요한 문화재이기 때문에 손상없이 비파괴적으로 수종을 추정하는 방법이 필요하다. 밀도를 알게 되면 수종을 추정하기 쉽다. 유전율식 목재수분계의 원리를 역으로 이용하면 함수율을 알고 있는 목재의 전건밀도를 얻을 수 있다는데 착안하여 연구를 수행하였다. 국내산 100여 개 수종, 122개 재감의 전건밀도를 치수법과 유전율식 목재수분계 추정법으로 구하여 두 계수의 상관관계와 회귀식을 찾았으며 문헌자료를 이용하여 회귀식의 유의성을 검정하였다. 치수법으로 측정한 전건밀도와 유전율식 목재수분계로 추정한 전건밀도는 매우 높은 상관관계를 나타냈다. 이 관계식을 이용하면 팔만대장경판의 전건밀도를 추정할 수 있으며 나아가 수종을 예측할 수 있을 것이다.

• 한국자동차공학회논문집
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• 제25권1호
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• pp.60-65
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• 2017

We designed and fabricated the engine oil monitoring sensor to measure engine oil deterioration through increased vehicle mileage. Since the condition of the engine oil can be affected by the state of the vehicle and its operating conditions, it should be directly measured and determined in every vehicle. The fabricated sensor has an aluminum parallel capacitor structure that measures capacitance related with the dielectric constant, which is one of the indices of oil deterioration. The size of the capacitor is small enough that it could be easily adapted on the oil level gauge without introducing any change in the design. The fabricated device is installed in the diesel engine to measure the change in capacitance accurately as the vehicle moved from 0 km (new engine oil state) to 11,364 km. The results showed the maximum value at around 5,000 km, and the values plateaued as mileage increased, corresponding with the measurement result of the TAN (Total Acid Number). Based on the results, the condition of the oil must be monitored regularly though oil change is recommended once the vehicle has traveled the distance of around 10,000 km.