• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.295-299
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• 1999

The (S $r_{1-x}$C $a_{x}$)Ti $O_3$(SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/ $SiO_2$/ Si) using RF sputtering method with substitutional contents of Ca. The maximum grain of thin films is obtained by substitution of Ca at 15[mol%]. The dielectric constant was increased with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mo1%]. The dielectric constant changes almost linearly in temperature ranges of -80~ +90[$^{\circ}C$]. The temperature properties of the dielectric loss have a stable value within 0.02 independent of the substitutional contents of Ca. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200(kHz).)..

• 대한화학회지
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• 제56권1호
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• pp.20-27
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• 2012

Complex permittivity spectra of Allyl Chloride (AC), 2-Butanone (2-BU) and their binary mixtures over the entire range of concentration were obtained using the Time Domain Reflectometry (TDR) technique in microwave frequency range at various temperatures. Static dielectric constant and relaxation time are obtained from complex permittivity spectra. Density ($\rho$) and refractive index ($n_D$) are also measured. These parameters are used to determine excess dielectric constant, excess inverse relaxation time, excess molar volume, excess molar refraction, polarity, Bruggeman factor and thermodynamic parameters viz. enthalpy of activation and entropy of activation. The values of static dielectric constant and relaxation time increases while density and refractive index decreases with the percentage of 2-Butanone in Allyl Chloride increases. Excess parameters were fitted to a Redlich-Kister equation.

• 한국세라믹학회지
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• 제43권2호
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• pp.131-135
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• 2006

In this study, the dielectric, magnetic and transport properties of $Gd_{0.33}Sr_{0.67}FeO_3$ have been analyzed. The dielectric loss anomaly was found to be around 170 K. The activation energy corresponding to relaxation process of this dielectric anomaly was 0.17 eV. From the temperature dependence of the characteristic frequency, we concluded that the elementary process of the dielectric relaxation peak observed is correlated with polaron hopping between $Fe^{3+}\;and\;Fe^{4+}$ ions. The electrical resistivity displayed thermally activated temperature dependence above 200 K with an activation energy of 0.16 eV. In addition, the temperature dependence of thermoelectric power and resistivity suggests that the charge carrier responsible for conduction is strongly localized.

• 한국자기공명학회논문지
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• 제5권2호
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• pp.130-137
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• 2001

Backbone dynamics of the catalytic residues in free and steroid-bound $\Delta$$^{5}$ -3- ketosteroid isomerase from Pseudomonas testosteroni has been examined by $^{15}$ N relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S$^2$, $\tau$$_{e}$, and R$_{ex}$). Tyr-34 and Asp-99 exhibit enhanced high-frequency (pico- to nanosecond) internal motions in the free enzyme, which are restricted upon ligand binding, while Asp-38 experiences severe restriction of the internal motions in the fee enzyme, suggesting that Tyr-14 and Asp-99 are more actively involved in the ligand binding than Asp-38. The results also indicate that the H-bond network in the catalytic cavity might be slightly strengthened upon ligand binding, which may have some implications on the enzyme mechanism.he enzyme mechanism.m.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권7호
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• pp.279-286
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• 2002

Linear and nonlinear complex permittivities were measured for copolymers of vinylidene cyanide(VDCN) with vinyl acetate(VAc), vinyl propionate(VPr), vinyl bezoate(VBz), styrene(St) and methyl methacrylate(MMA). Experimental results are well fitted by the function (equation omitted) except at low frequency where dc conduction dominates. The analysis of dielectric relaxation mechanism by combined knowledge about linear and nonlinear dielectric permittivities and dipoles give us informations about electrical and thermal motions in these copolymers. According to the analysis it could be found that the variation for temperature of the dielectric relaxation strength in these copolymers is related to the interaction between dipoles and the nonlinear dielectric effect factor R$_{s}$ is proportional to square of the dipolar correlation factor R$_{p}$././.

• 한국전기전자재료학회논문지
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• 제17권4호
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• pp.396-403
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• 2004

The dielectric properties of Y-ray irradiated and thermally aged polyetheretherketone (PEEK) have been investigated. Results of the temperature dependency of dielectric properties indicated that the glass transition temperature of aged PEEK increased as radiative and thermal ageing. The frequency dependency of dielectric properties implied that the magnitude of radiation and thermal induced dipoles, ions increased as radiative and thermal ageing. The values of relaxation intensity calculated using Cole-Cole's circular arc can be useful for evaluation of degradation level of PEEK.

• 한국전기전자재료학회논문지
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• 제17권6호
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• pp.668-672
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• 2004

Upon Debye's dielectric relaxation theory, we tried simple determination method of trap level in organic EL materials. From dielectric measurements in the 20 Hz - 1 MHz frequency range and in the 150 K - 320K temperature range, the depth of traps in Alq$_3$ filled with remaining electrons was determinated. Comparing to other determination techniques like TSL, or TL, the apparatus all we need is just simple LCR meter, thermometer and cooling method(liquid nitrogen). The mean activation energy is about 0.20 eV. It is in good agreement with previous determinations by other techniques like TSL. This results consolidate the validity of Burrow's transport mechanism model. Further intensified experiment with UV light on the dielectric absorption(Photodipolair effect) was nevertheless disturbed by the photoconductivity component.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.252-253
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• 2005

The dielectric relaxation properties of $^{60}Co$ gamma-ray irradiated Poly(vinylidene fluoride) (PVDF) containing various antioxidants have been investigated for radiation degradation. Cole-Cole's circular arcs were induced from the results of temperature and frequency dependency of dielectric properties with radiation dose. The magnitude of polarization of PVDF was decreased by adding antioxidants. The values of dielectric relaxation intensity calculated by using the Cole-Cole's circular arcs showed a certain tendency for radiation degradation.

• 한국안광학회지
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• 제2권1호
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• pp.9-16
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• 1997

강유천체 $Pb_5Ge_{3-x}Ti_xO_{11}$ 단결정을 x=0.015, 0.021, 0.03의 조성에 대하여 Czochralski법으로 성장시켰으며, 성장시킨 단결정의 색상은 맑고 투명한 연한 노란색이었다. $Pb_5Ge_{3-x}Ti_xO_{11}$ 단결정의 유전완화에 관한 연구를 위한 측정은 주파수범위 100 Hz에서 10 MHz까지 온도범위 $20^{\circ}C$에서 $600^{\circ}C$까지 변화 시키면서 하였다. 측정결과 유전을 최대값이 되는 온도는 Ti 성분이 증가함으로 낮은 온도로 이동하였으며, 유전율의 최대값의 크기는 Ti 성분의 증가에 따라 감소하였다. $Pb_5Ge_{3-x}Ti_xO_{11}$ 단결정의 유전응답의 주파수 의존성은 완화시간 분포와, Debye 완화형태를 가졌으며, 유전적 거동은 캐리어가 우세한 반응의 특징을 나타내었다.

• 한국음향학회지
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• 제36권6호
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• pp.387-393
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• 2017

베타 사이클로덱스트린(${\beta}$-Cyclodextrin, ${\beta}$-CD)(호스트)과 벤조산 유도체(게스트)의 수용액에 대하여 $25^{\circ}C$, 광대역 주파수영역(0.2 MHz ~ 50 MHz)에서 초음파 흡수계수를 측정하여 호스트와 게스트의 복합체 형성반응의 속도론적 연구를 행하였다. 특히 본 연구에서는 1 MHz이하의 초음파 흡수측정이 중요하다. ${\beta}$-CD와 벤조산 유도체의 상호작용에 의한 초음파 완화는 수 MHz영역에서 단일 완화현상의 전형적인 스펙트럼을 보였다. 단일완화현상의 원인은 ${\beta}$-CD와 벤조산 유도체의 복합체 형성반응에 의한 화학평행의 혼란상태에 의한것으로 해석하였다. 게스트 농도에 따른 완화주파수의 의존성으로부터 붕괴 속도상수($k_b=7.48{\times}10^6M^{-1}s^{-1}$), 평형상수($K=68.6M^{-1}$)를 결정하였다. 그리고 파장당 최대흡수치의 의존성으로부터 반응에 의한 표준체적변화(${\Delta}V=10.6{\times}10^{-6}m^3mol^{-1}$)를 구하였다. 또한 게스트 분자의 소수성 그룹이 복합체의 안정성에 중요한 역할을 하는 것을 알았다.