• Journal of Advanced Marine Engineering and Technology
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• 제34권6호
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• pp.864-870
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• 2010

수술이나 외상 등으로 동맥이나 정맥 속으로 공기가 유입되어 사망을 초래 할 수도 있는 공기 색전증을 신속하고 효율적으로 진단하기 위해 정전용량형 센서를 이용한 공기 감지 장치를 제안하였다. Tygon 튜브에 전극을 형성하여 전기적으로 커패시터를 구성하고, 튜브 내 유전체의 유전상수가 각각 다른 점을 이용하여 정전용량의 변화를 감지함과 동시에 공기의 유무를 검출한다. 변화된 정전용량의 값을 신호처리 회로를 통하여 주파수로 변환하고, 주파수 차이에 따른 공기유입 여부를 자동으로 알려주는 LabVIEW 모니터링 시스템을 구현하였다.

• 한국방재안전학회논문집
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• 제10권1호
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• pp.61-66
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• 2017

지표투과레이다 탐사에 있어서 지하매질의 전기적 특성 파악은 매우 중요하다. 지하매질의 전기적 특성에 따라 전자기파의 에너지가 상대적으로 작아져 경계면으로부터 반사가 어려워 질수 있다. 이 연구에서는 다양한(느슨하고 조립한) 조건의 모래지반에 대한 전기적 특성을 분석 한 결과, 마른모래에서는 상대밀도가 증가할수록 유전상수는 증가하였으며, 모래의 함수율이 증가할수록 유전상수와 전기전도도의 값은 증가 하였다.

• 한국세라믹학회지
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• 제29권10호
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• pp.827-835
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• 1992

The effects of CeO2 on the properties of cordierite-based glass-ceramics and its applicability to low firing temperature substrate were examined. Glass-ceramics were prepared by sintering the glass powder compacts at 900~100$0^{\circ}C$ for 3 h. Density, bending strength, dielectric constant and thermal expansion coefficient of the glass-ceramics were measured as functions of CeO2 contents and sintering temperatures. By adding CeO2, dense glass-ceramics were obtained below 100$0^{\circ}C$. dielectric constant and bending strength were more dependent on the porosity of glass-ceramics containing 5 wt% CeO2, sintered at 100$0^{\circ}C$ for 3 h, were as follows; relative density is 95.3%, bending strength is 178$\pm$11 MPa, dielectric constant is 4.98$\pm$0.20 (at 1 MHz) and thermal expansion coefficient is 33.7$\times$10-7/$^{\circ}C$. Therefore, the glass-ceramics containing 5 wt% CeO2 appeared to be suitable for low firing temperature substrate of electronic devices.

• Journal of Ceramic Processing Research
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• 제20권4호
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• pp.395-400
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• 2019

This study was conducted on the structural and electrical properties of (Ba0.7Sr0.3)TiO3 thin films prepared by the sol-gel and spin-coating methods in order to investigate their applicability to electrocaloric devices. All specimens showed a tetragonal crystal structure and lattice constants of a = 3.972 Å, c = 3.970 Å. The mean grain size of specimens sintered at 800 ℃ was about 30 nm, and the average thickness of 5 times coated specimens was 304~311 nm. In the specimen sintered at 750 ℃, The relative dielectric constant and loss of specimens measured at 20 ℃ were 230 and 0.130, respectively, while dependence of the dielectric constant on unit DC voltage was -8.163 %/V. The remanent polarization and coercive fields were 95.5 μC/㎠ and 161.3 kV/cm at 21 ℃, respectively. And, the highest electrocaloric property of 2.69 ℃ was observed when the electric field of 330 kV/cm was applied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1618-1620
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• 2004

The $Pb(Zr_{0.4}Ti_{0.6})O_3/Pb(Zr_{0.6}Ti_{0.4})O_3$ [PZT(4060)/(6040)] multilayered thin films were deposited by RF Sputtering method on the Pt/Ti/$SiO_2$/Si substrate. This procedure was repeated several times to form PZT(4060)/(6040) heterolayerd thin films. The effects on the structural and dielectric properties of PZT multilayered thin films were investigated. The MFM(Metal Ferroelectric Metal) type capacitors were made using the PZT(4060)/(6040) multilayered thin films deposited with optimum deposition condition. An enhanced dielectric property was observed in the PZT(4060)/(6040) multilayered thin films. The relative dielectric constant and dielectric loss at 100Hz of the PZT(4060)/(6040)-5 multilayered thin films were about 1106 and 0.016, respectively.

• 한국전기전자재료학회논문지
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• 제18권6호
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• pp.550-553
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• 2005

[ $Pb(Zr_{0.2}Ti_{0.8})O_3$ ] powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT thick films were fabricated by the screen-printing techniques on Pt/alumina substrates. The structural and dielectric properties were examined as a function of sintering temperature. The particle size distribution of the powder is bimodal with the mean particle size of about $1.2\;{\mu}m$. The average grain size of the PZT thick films sintered above $1000^{\circ}C$ was about $3.1\;{\mu}m$ and the thickness of the specimens was approximately $41\;{\mu}m$. The relative dielectric constant and dielectric loss of the thick films sintered at $1050^{\circ}C$ were 337 and $1.24\%$, respectively.

• 대한전기학회논문지
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• 제33권2호
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• pp.83-87
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• 1984

Influence of the metallization during the manufacturing of the ceramic multilayer capacitor on the dielectric properties was studied as a change of the capacity and the dissipation factor. Due to the change of the relative dielectric constant as a function of the measuring temperature the influence of the metallization could be obtained and the change of the dissipation factor as a function of the measuring frequency was anaysed. In order to investigate the boundary effect between the metallization and the dielectric a kind of microstructure model at the internal Grain and Grain Boundary was constructed and tried to analyse the change of the dielectric properties.

• 한국결정성장학회지
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• 제8권3호
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• pp.503-507
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• 1998

마이크로파 유전체로 응용되는 $xCaTiO_3-La(Zn_{1/2}Ti_{1/2})O_3$계의 소결시 고용조성 변화(x=0.4-0.6) 및 소결거동에 따른 유전특성에 조사하였다. 소결밀도가 감소함에 따라 유전상수는 감소하였으며 품질계수(Q)는 증가하다 일정한 값을 유지하였다. 고용체형의 경우 유전상수는 $CaTiO_3$조성 증가에 따라 증가하였다. $0.5\;CaTIO_3\;0.5\;La(Zn_{1/2}Ti_{1/2})O_3$의 경우 유전상수 48, 온도계수는 $-1ppm/^{\circ}C$를 나타내었다.

• 한국세라믹학회지
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• 제30권8호
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• pp.657-663
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• 1993

BaTiO3 sputtering targets of 3 inch diameter were prepared by sintering the CIP (Cold Isotatic Pressing) compacts at 136$0^{\circ}C$ for 3hrs. The apparent density and grain size were 97% and 30${\mu}{\textrm}{m}$, respectively. After BaTiO3 films were deposited on Si and Pt/Ti/SiO2/Si substrates using these targets, films were annealed at various conditions and the crystallization behavior, reaction with the substrate and the electrical properties were investigated. The films on both substrates required 5~20hrs furnace annealing for crystallization at the temperatures from $600^{\circ}C$ to 80$0^{\circ}C$. For the films on Si substrate, interaction between the film and the substrate was suppressed upt o $700^{\circ}C$ for 10 hrs and the relative dielectric constant was 30. As the annelaing temperature and time were increased, the relative dielectric constants of the films decreased due to the formation of silicate phases through the reaction with the substrate. For the BaTiO3 films on Pt/Ti/SiO2/Si substrate, the reaction with the substrate was further reduced when the annealing condition was identical to that for Si substrate, but the reaction between the layers in Pt electrode took place above $700^{\circ}C$. When the films were annealed at $600^{\circ}C$ where the stability of Pt electrode was sustained, relative dielectric constant was increased to 110 since the reaction with substrate was effectively reduced even for a longer annealing time and the crystallization was enhanced.

• 한국전기전자재료학회논문지
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• 제28권7호
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• pp.419-423
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• 2015

Sintering, microstructure, thermal conductivity and microwave dielectric properties of xLiF-(1-x)MgO ceramics (x=0.03~0.10 mol) were investigated. The high density was obtained in the specimens of $x{\geq}0.06$, i.e., 0.04 LiF-0.96 MgO in mol, whereas the amount of 0.03 mol LiF was insufficient to densify. From the result that the contact flattening in the sintered specimen was observed, the densification occurred through the liquid-phase sintering. The specimen of x=0.06 showed the highest room-temperature thermal conductivity. Relative density, thermal conductivity, dielectric constant, and quality factor ($Q{\times}f$) of the specimen for x=0.06 sintered at $900^{\circ}C$ for 4 h were 97.8%, $39.2Wm^{-1}K^{-1}$, 9.45, and 14,671 GHz, respectively.