• 제목/요약/키워드: Relative dielectric constant

검색결과 313건 처리시간 0.028초

복합쐐기의 유전체 영역에서 확장된 E-편파 회절계수 (E-polarized diffraction coefficients extended inside dielectric region of a composite wedge)

  • 김세윤
    • 전자공학회논문지D
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    • 제34D권7호
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    • pp.8-14
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    • 1997
  • The phusical optics approximation to an E-polarized diffraction by a composite wedge provides its diffraction coefficients in terms of finite series of cotangent functions. In this paper, its diffraction coefficients inside the dielectric part are extended to become the exact solution to the perfectly conducting wedge as its relative dielectric constant increases to infinite or decreases to 1. It is assured that the extended diffraction coefficients satisfy the boundary condition at th econducting interface and become zero in the artificially complementary region of the composite wedge.

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공간영역에서 코히어런트 단층촬영 기법을 이용한 Born 근사하에 유전체 기둥의 영상제현 (Image Reconstruction of Dielectric Cylinder Under Born Approximation Using a Coherent Tomographic Scheme in the Spatial Domain)

  • 서경환;김상기;김세윤;라정웅
    • 대한전자공학회논문지
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    • 제27권9호
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    • pp.1327-1335
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    • 1990
  • In this paper, using the principle of duality between the spatial and spectral domain, we proposed a new microwave imaging technique of a coherent tomographic formulation in the spatial domain and reconstructed the image of dielectric cylinder through simulation and experiment. The numerical and experimental results for the variety o object size, relative dielectric constant have shown the limitation of Born approximation to be used and the effect of retrieved images for various signal bandwidth.

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복합산화물 $(Ba Ca)TiO_3$-ZnO의 구조적 및 유전분극 특성 (The structural and dielectric polarization characteristics of composite oxide material in $(Ba Ca)TiO_3$-Zn)

  • 홍경진;임장섭;정우성;민용기;김용주;김태성
    • E2M - 전기 전자와 첨단 소재
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    • 제10권3호
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    • pp.239-246
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    • 1997
  • The ZnO is stabilize dielectric constant over a broad temperature range because its addition makes the relaxation time short. In this study, the composite oxide material (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ was mixed by ZnO additive material and the dielectric polarization characteristics was studied. The relative density was over 90[%] at all specimen in the structural characteristics. Among of the specimen, the relative density of (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ with ZnO (0.4mol) has a 95[%]. The grain size of composite oxide material with an increasing ZnO increased and it was 1.0[.mu.m]-1.22[.mu.m]. In the electrical characteristics, the charge and discharge current was increased by ZnO addition. The dielectric relaxation time was increased by space charge polarization at above 110[.deg. C] and the dielectric relaxation time was fixed by space charge polarization of para-dielectric layer at below 110[.deg. C]. The dielectric relaxation time was maximum when the grain size was small. The dielectric relaxation time is decreased with an additive material ZnO and interface polarization, existing void at the grain and grain boundary. The remnant polarization is increased and the coercive electric field is decreased by ZnO.

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메틸렌기에 의한 지방산 LB막의 전기적 특성 (Electrical Properties of Fatty Acid LB Films by Methylene Group)

  • 최용성;강기호;김도균;권영수
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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    • pp.349-352
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    • 1999
  • We have investigated the electrical characteristics of arachidic acid($C_{20}$), stearic acid(C_{18} and palmitic acid($C_{16}$) Langmuir-Blodgett(LB) films because the fatty acid systems have a same hydrophilic group and a different hydrophobic one (alkyl chain length). In this work, fatty acid systems were used as LB films and the status of the deposited films were confirmed by evaluating the capacitance and I-V characteristics. The conductivity of $C_{20}$, C_{18} and $C_{16}$ LB films obtained from I-V characteristics were about 5x $10^{15}$, 3x $10^{14}$ and 9x $10^{14}$[S/cm], espectively. These results have shown the insulating materials and could control the conductivity by changing the length of alkyl chain. Also, we have confirmed that the barrier height of fatty acid systems were about 1.32- 1.40[eV] and the relative dielectric constant were about 2.9~4.2. These values were almost the same ones obtained from dielectric characteristics.

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A Formation of the $Fluorocarbonated-SiO_2$ Films on Si(100) ASubstrate by $O_2/FTES-High$ Density Plasma CVD

  • Oh, Kyoung-Suk;Kang, Min-Sung;Lee, Kwang-Man;Kim, Duk-Soo;Kim, Doo-Chul;Choi, Chi-Kyu;Yun, Seak-Min;Chang, Hong-Young
    • 한국진공학회지
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    • 제7권s1호
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    • pp.106-117
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    • 1998
  • Fluorocarbonated-SiO2 films were deposited on p-type Si(100) substrate using FSi$(OC_2H_5)_3$ (FTES), and $O_2$ mixture gases by a helicon plasms source. High density $O_2$/FTES/Ar plasma of ~$10^{12} \textrm{cm}^{-3}$ is obtained at low pressure (<3mTorr) with RF power above 900 W in the helicon plasma source. Optical emission spectroscopy (OES) is used to study the relation between the relative densities of the radicals and the film properties. The FTES and $O_2$ gases are greatly dissociated at the helicon mode that is launched at the above threshold plasma density. FTIR and XPS spectra shows that the film has Si-F, and C-F bonds during the formation process of the film which may lower the dielectric constant greatly. The relative dielectric constant, leakage current density, and dielectric breakdown voltage are about 2.8, $8\times10^{-9}\textrm{A/cm}^2$, and > 12 MV/cm, respectively.

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Zirconium Titanate 세라믹 유전체에서 $Ta_2O_{5}$ 첨가가 유전특성에 미치는 영향 (The Influence of $Ta_2O_{5}$ Addition on Dielectric Characteristics of Zirconium Titanate Ceramics)

  • 이석진;이창화;이상석;최태구
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1992년도 춘계학술대회 논문집
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    • pp.129-132
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    • 1992
  • Rutile was among the first dielectric materials used. However, rutile exhibits a very high temperature coefficient of capacitance (about -750[ppm/$^{\circ}C$]) which resticts its practical application. Since this first use of titania, other materials have also been studied with the object of decreasing the temperature dependence whilst retaining favorable dielectric loss, Q, and relative permittivity. The temperature coefficient of temperature compensation capacitor is +100~750[ppm/$^{\circ}C$], dielectric constant 10~150. Low loss ceramics with dielectric constants in the 10~150 range also found application. Recently, their applications are extended in EMI filter and dielectric materials for microwave. There temperature coefficient of dielectric materials approaches 0[ppm/$^{\circ}C$]. The dielectric preperties of zirconia titanate ceramics prepared by addition of $Ta_2O_{5}$ were investigated.

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메틸렌기의 길이에 따른 지방산계 LB막의 유전 및 전기적 특성 (Dielectric and Electrical Characteristics of Fatty Acid System LB Filmes According to Length of Methylene Group)

  • 김도균;강기호;최용성;권영수
    • 한국전기전자재료학회논문지
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    • 제13권4호
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    • pp.300-305
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    • 2000
  • We have investigated the dielectric and electrical characteristics of palmitic acid(PA) stearic acid(SA) and arachidic acid(AA) Langmuir-Blodgett(LB) films because these fatty acid systems have a same hydrophilic group and a different hydrophobic one(methylene group or alkyl chain length). The fatty acid systems were used as LB films and the status of the deposited films was confirmed by evaluating the transfer ratio the UV absorption and the capacitance. The dielectric characteristics such as the frequency-capacitance characteristics and the dielectric dispersion and absorption characteristics of PA SA and AA through-plane were measured. The relative dielectric constants of PA, SA and AA LB films were about 3.0~4.6, 2.7~3.0 and 2.4~3.0 respectively. That is the relative dielectric constants were decreased in proportion to the chain length of methylene group. Also the dielectric dispersion and absorption of each fatty acid LB films have arisen from spontaneous polarization of dipole polarization in the range of 10$^4$~10$^{5}$ [Hz]. The conductivity of PA, SA and AA LB films obtained from I-V characteristics were about 9$\times$10$^{-14}$ , 3$\times$10$^{-14}$ and 5$\times$10$^{-15}$ [S/cm]. respectively. These results have shown the insulating materials and could control the conductivity y changing the length of methylene group. Also we have confirmed that the barrier height of fatty acid systems were almost the same ones obtained from dielectric characteristics.

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The Dielectric Properties of BaTiO3/SrTiO3 Heterolayered Thick films by Screen Printing Method

  • Nam, Sung-Pill;Lee, Young-Hie;Bae, Seon-Gi;Lee, Sung-Gap
    • Transactions on Electrical and Electronic Materials
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    • 제6권5호
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    • pp.210-213
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    • 2005
  • The $BaTiO_3/SrTiO_3$ heterolayered thick films were fabricated by the screen printing method on alumina substrates. The effect of the sintering temperature on the microstructure and dielectric properties of the $BaTiO_3/SrTiO_3$ thick films has been investigated. The relative dielectric constant and dielectric loss at 1 MHz of the $BaTiO_3/SrTiO_3$ heterolayered thick films with sintering temperature of $1350^{\circ}C$ were about 751 and 1.74, respectively. The remanent polarization $(P_r)$ of the pure $(Ba_{0.5}Sr_{0.5})TiO_3$ and $BaTiO_3/SrTiO_3$ heterolayered films are approximately $5.1\;{\mu}C/cm^2$ and $10\;{\mu}C/cm^2$. This study suggests that the design of the $BaTiO_3/SrTiO_3$ heterolayered thick films capacitor with different phase should be an effective method to enhance the dielectric and ferroelectric performance in devices.

$BaTiO_3$계 세라믹의 $Al_{2}O_{3}$ 첨가에 따른 유전 특성 (Dielectric properties of $BaTiO_3$ system Ceramics Doped with $Al_{2}O_{3}$)

  • 허영식;이원섭;이성갑
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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    • pp.402-405
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    • 2001
  • $(Ba_{0.6-x}Sr_{0.4}Ca_{x})TiO_{3}$ (x=0.10, 0.15, 0.20) ceramics were fabricated by the mixed-oxide method and their stuctural and dielectric properties were investigated with variation of composition ratio and an amount of $Al_{2}O_{3}$ (0.5, 1.0, 1.5. 2.0, 3.0 wt%) doping content. As a result of the X-ray diffraction BSCT specimens showed dense and homogeneous structure without presence of the second phase. The sintered density was decreased with increase an $Al_{2}O_{3}$ doping content. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing an amount of $Al_{2}O_{3}$ doping content. The dielectric loss is minimum for BSCT doped with 1.5wt% $Al_{2}O_{3}$ content. The tunability was decreased with increasing an Ca content and is about 4.2% for BSCT(50/40/10) doped with 2.0wt% $Al_{2}O_{3}$ content.

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위상배열 안테나용 $Al_2O_3가\; 첨가된\; (Ba, Sr, Ca)TiO_3$ 세라믹의 유전적 특성 (Dielectric Properties of $Al_2O_3-Doped\; (Ba, Sr, Ca)TiO_3$ Ceramics for Phased Array Antenna)

  • 이성갑;이영희
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제50권11호
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    • pp.550-554
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    • 2001
  • $(Ba_{0.6}Sr_{0.4}Ca_x)TiO_3 + yAl_2O_3$ wt% (x=0.10, 0.15, 0.20, y=0~3.0) ceramics were fabricated by the mixed-oxide method, and their structural and dielectric properties were investigated with variation of composition ratio and $Al_2O_3$ doping content. As results of the X-ray diffraction and microstructure analysis, all BSCT specimens showed dense and homogeneous structure without presence of the second phase. The sintered density was decreased with an increase of $Al_2O_3$ doping content. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing $Al_2O_3$doping content. The dielectric loss is minimum at BSCT doped with 1.5wt% $Al_2O_3$content. The tunability was decreased with increasing an Ca content and the BSCT(50/40/10) specimen doped with 2.0wt% $Al_2O_3$content showed the maximum value of 4.2%.

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