• 전기학회논문지
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• 제65권5호
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• pp.745-752
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• 2016

The parameters of Debye's equation were applied to analyze the frequency-dependent ground impedance of horizontally-buried wires. We present a new method, based on Debye's equation, of analyzing the effect of polarization on frequency-dependent ground impedance. The frequency-dependent ground impedances of a horizontally-buried wire are directly measured and calculated by applying sinusoidal current in the frequency range of 100 Hz to 10 MHz. Also, the results obtained in this work were compared with the data calculated from empirical equations and commercial programs. A new methodology using the delta-gap source model is proposed in order to calculate frequency-dependent ground impedance when the ground current is injected at the middle-point of the horizontal ground electrode. The high frequency ground impedance of horizontal electrodes longer than 30 m is larger or equal to its low frequency ground resistance. Consequently, the frequency-dependent ground impedance simulated with the proposed method is in agreement with the experimental data, and the validity of the computational simulation approach is confirmed.

• 전자공학회논문지
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• 제53권2호
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• pp.147-153
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• 2016

정보통신설비의 피뢰설계는 정보통신기기 동작의 신뢰성을 향상시키기 위해서 매우 중요한 요소이다. 특히, 뇌격전류에 의한 접지전극의 과도전위상승은 전원설비 및 정보통신기기의 절연내력의 기초 자료가 되기 때문에 정확한 해석이 요구된다. 접지전극의 과도전위상승은 접지임피던스로부터 계산되어지며, 접지임피던스는 접지전극의 형상과 토양의 주파수의존성에 크게 의존적이다. 토양의 주파수의존성은 인가된 전계에 의한 토양의 유전체 특성을 해석할 수 있는 디바이식을 적용하였다. 또한 접지임피던스로부터 과도전위상승을 계산하는 방법을 제시하였다. 디바이식을 적용한 과도전위상승 결과를 분석하기 위해서 전송선로 모델과 대지저항률이 일정한 경우에 대해서 각각 시뮬레이션을 수행하였다. 수평접지전극은 30 m이며, 표준 뇌격전류파형에 대해서 대지저항률이 10, 100, $1000{\Omega}{\cdot}m$에 대해서 각각 분석하였다. 그 결과 디바이식을 적용하여 계산된 수평접지 전극의 과도전위상승이 다른 모델의 경우보다 더 낮게 나타났다.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.892-901
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• 2018

Because of excellent electrical properties, epoxy resin is widely used in packaging and casting power equipment. Moisture and temperature in the environment are inclined to seriously affect the insulation tolerance of epoxy resin. This work focuses on the aging characteristics of epoxy resin in hygrothermal environment. Scanning electron microscopy images show that there are micro-crack, micro-slit and holes inside aged samples. The moisture absorption process undergoes three equilibrium stages and it does not follow the Fick's second law. Observing the change of hydrogen bonds in the infrared spectra of the dried samples, it is found that chemically moisture absorption immerges when the physical moisture absorption entered the third equilibrium stage. By Debye equation to fit the imaginary part of the dielectric constant, it is concluded that the uniformity of water molecule has a great influence on the electrical conductivity loss. Furthermore, the polarization loss can be more easily affected by water molecules than small free molecules. After the aged samples being dried, their real and imaginary part of the dielectric constant descend, but their original electrical properties cannot completely restored. After chemical moisture absorption appears inside the material, the residual space charges increase significantly and the charge dissipation rate slow down obviously.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.739-742
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• 2000

Nanostructured ZnS thin films were grown on the slide glass substrate by the chemical bath deposition using an aqueous so1ution Of ZnSO$_4$and CH$_3$CSNH$_2$at 95$^{\circ}C$. The average grain sizes of the ZnS thin film estimating from the Debye-Scherrer formula are 4.8 nm. The optical transmittance edge of the ZnS thin films (4.0 eV) was shifted to the shelter wavelength compared with that of the bulk ZnS (3.67 eV) due to the quantum size effects. The ZnS thin films showed a strong photoluminescence intensity and a sharp emission band from 410 to 480 nm 3t room temperature. The PWHM of photoluminescence peak was about 40 nm. For the viloet(410 nm) and blue(480 nm) emission of the ZnS thin films, the temperature dependence can be described by an Arrhenius equation with an activation energy of 168 and 157 meV, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1102-1104
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• 1995

This study presents the results of an investigation on the electrical characteristics of $PVF_2$ film, to be regarded as the excellent piezo and pyroelectricity, using dielectric relaxation technique by the variation of temperature and frequency. As one of the results, we confirmed that crystal form with Infrared absorption and XRD was ${\alpha}$ type and its crystalline was 59[%]. Also, the results of observation conformed to Debye theory for frequency variation of relative permitivity and dielectric relaxation. Especially, we confirmed each constant values in comparision with equation related to diffusion behavior of ion, so we obtained that activation energy was computed 17.25[kcal/mole] from the relation curve with frequency and temperature.

• 한국자기학회지
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• 제25권1호
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• pp.10-15
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• 2015

높은 전기전도도를 가진 비자성 금속 코어와 연자성 쉘을 가진 복합와이어의 자기임피던스를 원주방향 투자율로 표현하는 모델을 맥스웰 방정식으로부터 유도하였다. Cu(직경 $100{\mu}m$)/$Ni_{80}Fe_{20}$(두께 $15{\mu}m$) 코어/쉘 복합 와이어를 전기도금방법으로 제작하였다. 코어/쉘 복합 와이어의 길이방향으로 10 kHz에서 10 MHz 범위의 주파수를 가지는 교류전류와 0 Oe에서 200 Oe 범위의 직류 자기장을 가하여 임피던스 스펙트럼의 자기장 의존성을 측정하였다. 유도된 모델을 적용하여 측정된 임피던스 스펙트럼으로부터 원주방향 복소 투자율 스펙트럼을 뽑아내었다. 뽑아낸 원주방향 복소 투자율 스펙트럼은 단일 완화주파수의 Debye 식으로 매우 잘 곡선적합되는 완화형 분산을 보였다. 원주방향 복소 투자율 스펙트럼의 자기장 의존성을 분석하여, 본 코어/쉘 복합 와이어의 경우 길이 방향의 자기이방성을 가지며 원주방향으로의 자화회전이 완화형 복소 투자율 스펙트럼에 기여하는 단일 성분이라는 것을 규명하였다.

• 멤브레인
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• 제12권1호
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• pp.41-50
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• 2002

하전된 마이크로채널의 전기이중층에서 계면동전기 흐름에 의해 발생되는 흐름전위는 일반적 Helmholtz-Smoluchowski 관계식으로부터 중공사 멤브레인 기공의 제타전위를 결정하는데 적용된다. 흐름전위는 실제 운전상황이나 물리화학적 조건에서의 표면특성 및 기공과 입자간 상호작용에 대한 유용한 실시간 정보를 제공함이 알려져 있다. 무리화학적 인자들이 주공사에 의한 여과에 미치는 영향을 투과플럭스와 흐름전위의 동시적 모니터링으로 고찰하였다. 특히, 본 연구에서는 중공사의 위치에 따른 흐름전위를 측정함으로써 중공사 길이 방향과 멤부레인 오염 진행에 따라 달라지는 케이크층 효과를 규명하는 실험방법을 다루었다. 실험결과, 입자농도가 증가할수록 투과플럭스는 감소하나 흐름전위는 증가하였다. 입자농도가 증가하면서 케이크층 성장은 활발하지만 쌓인 하전 입자들의 표면전하 효과로 흐름전위는 증가한 것이다. 용액의 이온화 세기를 KCI 0.1 mM에서 10mM로 증가하면 투과플럭스와 흐름전위가 함께 감소하였다. 이는, 이온화 세기의 증가로 라텍스입자 주위의 Debye 길이 감소로 치밀한 케이크층이 형성되고, 전기이중층의 얇아진 확산층에 의한 이온흐름의 약화로 흐름전위는 감소한 것을 판단된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.37-37
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• 2010

Silicate-silsesquioxane or siloxane-silsesquioxane hybrid thin films are strong candidates as matrix materials for ultra low dielectric constant (low-k) thin films. We synthesized the silicate-silsesquioxane hybrid resins from tetraethoxyorthosilicate (TEOS) and methyltrimethoxysilane (MTMS) through hydrolysis and condensation polymerization by changing their molar ratios ([TEOS]:[MTMS] = 7:3, 5:5, and 3:7), spin-coating on Si(100) wafers. In the case of [TEOS]:[MTMS] 7:3, the dielectric permittivity value of the resultant thin film was measured at 4.30, exceeding that of the thermal oxide (3.9). This high value was thought to be due to Si-OH groups inside the film and more extensive studies were performed in terms of electronic, ionic, and orientational polarizations using Debye equation. The relationship between the mechanical properties and the synthetic conditions of the silicate-silsesquioxane precursors was also investigated. The synthetic conditions of the low-k films have to be chosen to meet both the low orientational polarization and high mechanical properties requirements. In addition, we have investigated a new solution-based approach to the synthesis of semiconducting chalcogenide films for use in thin-film transistor (TFT) devices, in an attempt to develop a simple and robust solution process for the synthesis of inorganic semiconductors. Our material design strategy is to use a sol-gel reaction to carry out the deposition of a spin-coated CdS film, which can then be converted to a xerogel material. These devices were found to exhibit n-channel TFT characteristics with an excellent field-effect mobility (a saturation mobility of ${\sim}\;48\;cm^2V^{-1}s^{-1}$) and low voltage operation (< 5 V). These results show that these semiconducting thin film materials can be used in low-cost and high-performance printable electronics.