• 한국지반환경공학회 논문집
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• 제13권12호
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• pp.17-25
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• 2012

본 논문에서는 TDR 장비를 사용하여 지반특성에 따라 변화하는 유전상수를 측정하였으며, 지반의 함수비 및 밀도와의 상관성을 분석하였다. 또한, 유전상수를 이용한 지중 공동탐사기법의 적용성을 평가하기 위하여 공동의 크기에 따른 유전상수의 변화 정도를 측정하였다. 실험결과 지반의 유전상수는 함수비와 밀도가 증가함에 따라 선형적인 증가 경향을 나타내는 것으로 평가 되었으며, 일정한 관계식으로 표현할 수 있었다. 또한, 지반의 유전상수는 공동의 크기에 따라 일정한 경향을 나타내며 변화하는 것으로 평가되었다. TDR 기법을 사용하여 측정된 유전상수값은 지반의 함수비, 밀도와 일정한 상관관계를 나타내고 있음을 확인하였으며, 지중 공동탐사에 관한 기초자료로서 활용할 수 있을 것으로 판단된다.

• 대한전기학회논문지
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• 제34권8호
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• pp.323-330
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• 1985

Dielectric loss tangent and ac dielectric strength of GFRP (Glass Fiber Reinforced Plastics, G-10)was investigated as parameters of mechanical and thermal stresses, in order to study the basic dielectrical characteristics of composite insulating materials. The dielectric loss tangent was increased and the ac dielectric strength was decreased with increase in the mechanical stresses beyond the mechanical yield point on account of fiber-matrix debonding, but the dielectric constant was not varied sigificantly. the dielectric strength of G-10 was about 2 MV/cm and the dielectric constant was about 4.8.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.316-320
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• 1991

The dielectric properties of the ZnO varistor fabricated by the method of 3-composition seed grain was studied. In this paper, we present the C-V charateristic for the specimen. The dielectric constant and disppation which changed with additives may be explained on the basis of the deplation layer; the presence of deplation layer has been inferred by donor and state density obtained from the $1/C^2$ vs. V.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.397-404
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• 2001

This study describes the effect of γ-ray irradiation on the properties of insulation materials for low voltage cables in a nuclear power plant. The radiation effects were characterized by measuring OIT, FTIR, electrical properties of the irradiated specimens. As a result, they showed the decrease of OIT and the increase of chemical structural defects with the increase of γ-ray amount. Also, the electrical properties such as dielectrical constant, tan $\delta$ and current were changed by aging. These changes may come from the increase of chemical structural defects by $\delta$-ray irradiation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.158-162
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• 1997

In this paper, the electrical and dielectrical properties were investigated in Pb(Zr,Ti)O$_3$-Pb(Mn,Nb)O$_3$ ceramics which are manufactured with the substitution of Ba in site Pb. In older to increase the del and Kp , Ba was substitued to site Pb from 0 to 0.1 by 0.02 mol%. As the Ba substitution is increased, dielectric constant is increased and electricmachanical coupling factor showed the maximum value at Ba 0.06mol% and the mechanical qualify factor is decreased and the tetragonality and the grain size are decreased as the Ba substitution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.288-291
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• 2002

An alkoxide-based sol-gel method was used to fabricate $(Pb_{x},Sr_{1-x})$TiO3 (PST) thin films on a Pt/Ti/SiO2/Si substrate, and the dielectric properties of the PST thin films were investigated as a function of the Pb/Sr composition for use in tunable microwave device applications. The dielectric properties of the PST films were strongly dependent on the Pb/Sr ratio. The dielectric constant and dielectric loss of the PST films increased with increasing Pb content, and the figure of merit (FOM) reached a maximum value of 27.5 at a Pb/Sr ratio of 4:6. The tunability increased with increasing Pb content. The dielectric constant, loss factor, and tunability of PST (50/50) thin films were 404, 0.023, and 51.73%, respectively. From the result, the PST films with good dielectric properties are useful candidates for tunable microwave device.

• 한국세라믹학회지
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• 제34권2호
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• pp.123-130
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• 1997

본 연구에서는 유전상수가 크고, 유전체 손실이 적으며, 사용온도 범위에서 정전용량 변화율(TCC : tem-perature coefficient of capacitance)이 작고, 고압에 견딜 수 있는 재료를 개발하기 위하여 중고압용 capacitance의 기본재료로써 (Sr.Pb.Ca)TiO3-xBi2O3.3TiO2 계에서 Bi2O3.3TiO2의 mol.%를 5, 6, 7, 8, 9 mol.%로 변화시켰으며, 그 결과 고용한계 함량이 6mol.%이며, 6mol.%이상에서는 침상구조의 증가에 기인하여 유전율이 다시 감소하는 경향을 보였다. dopant로써 SiO2, Nb2O3, MnO2를 선정하여 첨가한 결과, MnO2를 첨가한 것이 유전성질이 가장 우수하였으며, MnO2의 함량이 0, 0.15, 0.3, 0.45 wt.% 증가함에 따라서 유전율의 감소와 동시에, TOC특성의 급격한 향상을 가져왔다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권7호
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• pp.514-520
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• 1999

Ferroelectric PZT(30/70)/PZT(70/30) heterolayered thin films were fabricated by spin-coating method on the $Pt/Ti/SiO_2Si$ substrate alternately using(30/70) and PZT(70/30) alkoxide solutions prepared by sol-coating method. The coating and heating procedure was repeated six times to form PZT heterolayered films, and thickness of the film obtained by one-times drying/sintering process was about 40-50 nm. All PZT heterolayered films, showed dense and homogeneous structure without the presence of rosette sturctrue. The relative dielectric constant, remanent polarization and leakage current density of PZT heterolayered films were superior to those of single composition PZT(30/70) and PZT(70/30) films, and those values for the PZT-6 film were 975, $21 \muC/cm^2\; and\; 8\times10^{-9}\; A/cm^2$, respectively. And the PZT-6 heterolayered film showed fairly good fatigue characteristics of remanent polarization and coercive field after application of $10^8$ switching cycles.

• 한국전기전자재료학회논문지
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• 제14권10호
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• pp.796-801
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• 2001

Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the solid-state reaction method, and especially PZT(90/10) and PZT(10/90) powders were derived by the sol-gel method. All specimens showed a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increased in sintering temperature, the values for the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 14.4$\mu$m and 9.8$\mu$m, respectively. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247. 2.06%, respectively. The coercive field and the remanent polarization of x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 8.5kV/cm, 13$\mu$C/$\textrm{cm}^2$ and 17.2kV/cm, 28 $\mu$C/$\textrm{cm}^2$, respectively. The pyroelectric coefficient of the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 5.64$\times$10$^{-8}$ C/$\textrm{cm}^2$K and 2.76$\times$10$^{-8}$ C/$\textrm{cm}^2$K, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.799-801
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• 1988

This paper was studied on the effects of Ca-La-Nb substitution and Zr/Ti ratio variation to Pb(Zr, Ti)$O_3$ system on structural, electrical, optical and sound level characteristics in order to develope the piezoelectric and electrooptic ceramic devices. Also the specimens were prepared by the two stage sintering technique. The molecular formular was X($CaO{\cdot}1/4La_{2}O_{3}{\cdot}1/4Nb_{2}O_{5}){\cdot}(1-X)Pb(Zr_{Y}Ti_{1-Y})O_{3}$(x=100X, y=100Y), and the variation of x was $6{\sim}12$, y was 60${\sim}$49 and second stage sintering time was 20${\sim}$40 hours. The experimental results obtained from this study are as follows : 1. The density was decreased, the grain size was increased according to increase of Ca-La-Nb substitution. 2. The crystal structure was rhombohedral in composition 6/60/40, and the crystal structure was tetragonal and cubic according to increase of Ca-La-Nb substitution. 3. The Ca substitution of PZT system enhanced the sintering property. The Pb site vacancy resulting from the substitution of La-Nb increased the dielectrical constant, the piezoelectric charge constant, the dielectric loss and decreased the coercive field. 4. The resistivity of PZT system which has the P type conduction mechanism increased according to substitution of La-Nb because of the substituent acting as donor. 5. The PZT ceramics varied from ferroelectric substance according to increase of Ca-La-Nb substituent. The coercive field and saturation remanent polarization decreased, and at last straight line according to increase of La-Nb substitution. 6. The amount of Ca-La-Nb substitution to improve the light transmittance of speciment was 10 mol%, the Zr/Ti ratio was 49/51, and the second stage sintering time was 40 hours. 7. According to Ca-La-Nb substitution, the specimens was to be transparent. The 7.5/51/49 specimen was suitable for transparent sound vibrator because it had 58% light transmittance (thick 0.2[mm], wave length 700[mm]) and 48% electromechanical coupling factor.