• E2M - 전기 전자와 첨단 소재
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• 제4권1호
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• pp.53-64
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• 1991

절연체중에 있는 하전입자의 거동은 절연재료의 특성에 많은 영향을 준다. 본 연구에서는 호핑모델에 의한 수치해석법을 TSC특성과 쌍극자분극에 대한 TSC특성은 차이가 있었다. 실험과 대응시켜 가동이온에 관한 물성정수의 평가를 하였다. 호핑모델에 의해서 불포화 TSC와 I-V특성의 수치계산을 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1990년도 추계학술대회 논문집
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• pp.91-94
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• 1990

The behavior of charged particle in dielectrics have a many effects on characteristics of the insulating materials. In this paper, numerical analysis method by hopping model was investigated application of TSC. As the results, there was a difference between characteristics of TSC by dipole polarization. Physical constant of movable ion corresponding to the experimental results was evaluated and also. Numerical calculations of unsaturated TSC and I-V characteristics were carried out by was of hopping model.

• 대한전기학회논문지
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• 제37권3호
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• pp.163-170
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• 1988

In order to investigate the mechanism of pyroelectricity on polyvinylidene fluoride film, the observations were carried out on the characteristics of infrared spectra, thermally stimulated current and pyroelectric current. As the results obtained from the study, it was concluded that the origin for thermally stimulated current exhibited above room temperature can be attributed to hole injected from anode during poling process. Futhermore it is clarified also that the origin of pyroelectricity observed on the specimen concerned is to spontaneous polarization of CF dipole attached to molecular chain segment, however, the fraction of spontaneous polarization is largely influenced by the amount of hole injected from anode.

• 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.

• 한국수소및신에너지학회논문집
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• 제2권1호
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• pp.15-21
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• 1990

Nickel-hydrogen battery systems with metal hydride alloys are expected to have both higher energy density and lower pollution than nickel-cadmium cells. Nickel-hydrogen storage cells are expected to be well-suited for use in space crafts for a large capacity power storage system. Their major advantages are not only a capability of deep DOD(depth of discharge) using but also with excellent durability under excessive overcharging and overdischarging. In this study, the charge/discharge capacities, anodic polarization characteristics and durability for the continious charge/diacharge cycling of the $Ti_{1-X}Zr_XVNi$ and $Ti_{1-X}Zr_XV_{0.5}Ni_{1.5}$ alloys were measured by electrochemical method. The electrode properties of the copper or nickel plated $Ti_{1-X}Zr_XV_{0.5}Ni_{1.5}$ alloys were examined with a battery charge/discharge testing system in the temperature range of -5 to $25^{\circ}C$.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.258-261
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• 2000

Highly (h00)-oriented (Ba, Sr)TiO$_3$(BST) thin films were grown by pulsed laser deposition on the perovskite LaNiO$_3$(LNO) metallic oxide layer as a bottom electrode. The LNO films were deposited on SiO$_2$/Si substrates by rf-magnetron sputtering method. The crystalline phases of the BST film were characterized by x-ray $\theta$-2$\theta$, $\omega$-rocking curve and $\psi$-scan diffraction measurements. The surface microsturcture observed by scanning electron microscopy was very dense and smooth. The low-frequency dielectric responses of the BST films grown at various substrate temperatures were measured as a function of frequency in the frequency range from 0.1 Hz to 10 MHz. The BST films have the dielectric constant of 265 at 1 kHz and showed multiple dielectric relaxation at the low frequency region. The origin of these low-frequency dielectric relaxation are attributed to the ionized space charge carriers such as the oxygen vacancies and defects in BST film, the interfacial polarization in the grain boundary region and the electrode polarization. We studied also on the capacitance-voltage characteristics of BST films.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권3호
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• pp.1-11
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• 2004

매립지 침출수로 오염된 지반의 오염도 조사에 유전상수 측정기법의 적용성을 평가하기 위하여 매립지 침출수로 오염된 간극수를 포함한 사질토 지반의 유전특성을 분석하였다. 본 연구에서는 75kHz-12MHz 범위의 주파수에서 유전 상수를 실수부와 허수부로 구분하여 분석을 수행하였다. 유전상수 실수부는 공간전하분극과 배향분극의 발현정도에 영향을 받기 때문에 침출수 농도가 증가함에 따라 저주파 영역에서는 유전상수의 실수부 값이 증가하는 경향을 나타내었으나, 고주파 영역에서는 감소하는 경향을 나타내었다. 유전상수 허수부의 경우에는 측정 주파수에 관계없이 침출수의 농도가 증가함에 따라 전류전도에 의한 에너지 손실량이 증대되어 유전상수 허수부가 증가하는 경향을 나타내었다. 유전상수의 실수부와 허수부가 간극수 내 침출수 농도에 따라 변하는 것에 기초하여 유전상수 측정기법이 침출수로 오염된 지반의 오염도 평가에 효과적으로 적용될 수 있음을 확인하였다.

• 한국세라믹학회지
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• 제19권4호
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• pp.316-320
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• 1982

The effect of the additive on dielectric properties of $BaTiO_3$ containing 0.030 mol% $Dy_2O_3$ was investigated function of frequency from 5$\times$104 to 0.3$\times$107cps and temperature from 25 to 1$25^{\circ}C$. The dielectric constant increased with increasing $Dy_2O_3$ concentration from 0 to 0.05mol% due to space charge polarization. However, the dielectric constant decreased for further increase of $Dy_2O_3$ concentration due to density increase. The dielectric constant exhibits rapid change at the Curie temperature and the Curie temperature drops from 122 to 116$^{\circ}C$ with increasing amount of $Dy_2O_3$ concentration.

• 한국세라믹학회지
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• 제26권1호
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• pp.1-6
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• 1989

The phenomena that the electrical conductivity of rutile single crystal changes with time were investigated along the a and c crystallographic axes, at 85$0^{\circ}C$ and Po2 in the range of 1~10-18.5atm. The D.C. conductivity decreased with and saturated some value after ca. 100 hours. But the A.C. conductivity showed no time dependence in the whole Po2 range. These experimental results suggest that the time dependence of D.C. conductivity of rutile single crystal is due to space charge polarization effect; the electrode was Pt which is complete electronic conductor, while the sample was TiO2 which is mixed conductor.

• 한국세라믹학회지
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• 제21권2호
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• pp.121-126
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• 1984

The dielectric properties of $BaTiO_3$ containing 0~0.3mol% and ZnO respectively as additives were investigated as a function of temperature from $25^{\circ}C$ to 14$0^{\circ}C$ and frequency from 24 KHz to 15MHz. The density of sintered $BaTiO_3$ was increased with addition of increasing to 0.15mol% amounts of $Sb_2O_3$ and the dielectric constant was also increased. This is due to space charge polarization with Ba vacancies. Above 0.15mol% $Sb_2O_3$ the density was decreased and the dielectric constant was also decreased due to occuring the discharge through voids. The density of sintered $BaTiO_3$ was decreased with addition of increasing to 0.15mol% amounts of ZnO and the dielectric constant was decreased due to occuring the discharge through voids. Above 0.15mol% ZnO the density was increased and the dielectric constant was also increased.