• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1466-1468
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• 1994

In this paper Dielectric and strain properties of (1-x-y)PMN-yPT-xST Ceramics have been investigated as a function of the amount of $SrTiO_3(ST)$. The $SrTiO_3$ content is ranged from 0.01-0.06(wt%). As the amount of ST is increased, dielectric constant has a maximum value at 0.05 mol composition. The Curie temperature is decreased linearly with increasing ST composition and Polarization properties have been investigated. Coercive field and ramnant polarization has a maximum value at 0.01mol composition.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.11-17
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• 2001

In this paper, spherical Luneburg lens antennas have been systematically analyzed using the Eigenfunction Expansion Method (EEM), The developed technique has capability of performing a complete 3-D analysis to characterize the multi-layered dielectric spherical lens with arbitrary permittivity and permeability. This paper describes the analysis technique, and presents the results of the parametric study of Luneburg lens antennas by varying design parameters suoh as the diameter of the lens antenna (up to 80 wavelength), number of spherical shells (up to 30 shells), air-gaps between spherical shells, and dielectric loss of the material. Many representative engineering design curves including the far-field patterns, wide-angle sidelobe characterizations, antenna efficiency have been presented.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.264-269
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• 2010

This paper presents the analysis of the dielectric characteristics of a hot $SF_6$ gas in a gas circuit breaker. Hot gas flow is analyzed using the FVFLIC method considering the moving boundary, material properties of real $SF_6$ gas, and arc plasma. In the arc model, the re-absorption of the emitted radiation is approximated with the boundary source layer where the re-absorbed radiation energy is input as an energy source term in the energy conservation equation. The breakdown criterion of a hot gas is predicted using the critical electric field as a function of temperature and pressure. To validate the simulation method, breakdown voltage for a 145kV 40kA circuit breaker was measured for various conditions. Consistent results between the simulation and experiment were confirmed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.5-8
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• 1994

In this paper, Dielectric and strain properties of (1-x-y)PMN-yPT-xST Ceramics hale been investigated as a function of the amount of SrTiO$_3$(ST). The SrTiO$_3$ content is ranged from 0.01-0.05(wt%). As the amount of ST is increased, dielectric constant has a maximun value at 0.05 mol% composition. The Curie temperature is decreased linearly with increasing ST composition and Polarization properties have been investigated. Coercive field and remnant polarization has a maximum value at 0.01mo1% composiion.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1493-1495
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• 2003

EVAOH (ethylene-vinyl acetate-vinyl alchol terpolymers) were prepared by using the transesterification reaction between ethylene-vinyl acetate copolymer and alchol. Structural and thermal analyses were accomplished with FTIR and DSC. XLPE (crosslinked polyethylene) and EVAOH were blended using a two-roll mill and their water tree and dielectric loss characteristics were investigated. It is found that the water tree characteristics of XLPE were improved by the addition of EVAOH. It was also found that the extent of improvement of water tree and dielectric loss characteristics of XLPE/EVAOH blends depends on the kind and concentration of EVAOH.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.253-254
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• 2007

In this study, in order to develop low temperature sintering multilayer piezoelectric actuator, PMN-PNN-PZT system ceramics were fabricated using $Li_2CO_3-Bi_2O_3$-CuO as sintering aids and their piezoelectric and dielectric characteristics were investigated as a function of heating rate. At sintering temperature of $900^{\circ}C$, with increasing heating rate, electromechanical coupling factor(kp), mechanical quality factor(Qm) and dielectric constant $({\varepsilon}_r)$ were increased.

• 한국항행학회논문지
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• 제16권4호
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• pp.635-640
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• 2012

본 논문에서는 접지된 2개의 유전체층 위의 도체띠 격자구조에 의한 TE (Transverse Electric) 산란문제를 도체경계조건과 수치해석 방법인 FGMM (Fourier-Galerkin Moment Method)를 적용하여 해석하였으며, 이 때 유도되는 표면전류밀도는 미지의 계수와 단순한 함수인 지수함수의 곱의 급수로 전개하였다. 전반적으로, 제안된 구조에서 영역-2의 유전체층의 비유전율 ${\epsilon}_{r2}$과 유전체 층의 두께 $t_2$가 증가함에 따라 반사전력이 증가하였다. 반사전력의 급변점들은 공진효과에 기인한 것으로 과거에 wood's anomaly라고 불리워졌으며, 수치계산 결과들은 기존 논문의 결과들과 일치하였다.

• Journal of the Optical Society of Korea
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• 제18권4호
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• pp.359-364
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• 2014

We report parameters that allow the dielectric functions ${\varepsilon}={\varepsilon}_1+i{\varepsilon}_2$ of $AlAs_xSb_{1-x}$ alloys to be calculated analytically over the entire composition range $0{\leq}x{\leq}1$ in the spectral energy range from 0.74 to 6.0 eV by using the dielectric function parametric model (DFPM). The ${\varepsilon}$ spectra were obtained previously by spectroscopic ellipsometry for x = 0, 0.119, 0.288, 0.681, 0.829, and 1. The ${\varepsilon}$ data are successfully reconstructed and parameterized by six polynomials in excellent agreement with the data. We can determine ${\varepsilon}$ as a continuous function of As composition and energy over the ranges given above, and ${\varepsilon}$ can be converted to complex refractive indices using a simple relationship. We expect these results to be useful for the design of optoelectronic devices and also for in situ monitoring of AlAsSb film growth.

• Current Optics and Photonics
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• 제2권5호
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• pp.482-487
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• 2018

We investigate the radiation characteristics of radially polarized light and azimuthally polarized light through plasmonic subwavelength-scale annular slit (PSAS) structures, by means of both theoretical and numerical methods. Effective-medium theory was utilized to analyze the characteristics of PSAS structures, and the corresponding results showed that PSAS structures can function as a metallic medium for azimuthally polarized light, or as a low-loss dielectric medium for radially polarized light. Numerical calculations based on the finite-element method were also performed, to verify the theoretical analyses. It turned out that the numerical results supported the theoretical results. Moreover, we exploited the PSAS structures in novel nanophotonic elements with dual functionalities that could selectively focus or pass/block incident light, depending on its polarization state. For example, if PSAS structures were implemented in the dielectric region of a metallic Fresnel zone plate, the modified zone plate could function as a blocking element to azimuthally polarized light, yet as a focusing element to radially polarized light. On the contrary, if PSAS structures were implemented in the metallic region of a metallic Fresnel zone plate (i.e. the inverted form of the former), it could function as a focusing element to azimuthally polarized light, yet as a simple transparent element to radially polarized light.

• 한국안광학회지
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• 제7권2호
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• pp.209-215
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• 2002

본 실험에서는 HWE 방법으로 성장시킨 SnSe 단결정 박막에 대한 특성을 조사하였다. 성장된 박막의 결정 구조와 격자 상수를 알아보기 위하여 X-ray diffraction(XRD)에 의한 회절 패턴을 측정하고, 단결정 박막의 결정성을 확인하기 위하여 double crystal X-ray diffraction(DCXRD)에 의한 회절 패턴을 측정하여, 원료부와 열벽부 그리고 기판의 온도 변화에 따른 반치폭을 알아보았다. Rutherford back scattering(RBS)을 측정하여 Sn과 Se의 조성비를 확인하고, 실험값과 이론값의 차이를 조사하였다. 박막의 표면 상태는 atomic force microscopy(AFM) 사진과 주사 전자 현미경(SEM) 사진으로 관찰하여 결정구조와 성장 온도와의 연관성을 조사하였다. 광학 상수는 Spectroscopic Ellipsometry(SE) 방법을 이용하여 단결정 박막의 굴절률(n), 유전상수(${\varepsilon}$), 반사율(R) 그리고 흡수 계수(${\alpha}$) 등 광학 상수를 측정했다.