• 한국세라믹학회지
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• 제26권1호
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• pp.1-6
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• 1989

The phenomena that the electrical conductivity of rutile single crystal changes with time were investigated along the a and c crystallographic axes, at 85$0^{\circ}C$ and Po2 in the range of 1~10-18.5atm. The D.C. conductivity decreased with and saturated some value after ca. 100 hours. But the A.C. conductivity showed no time dependence in the whole Po2 range. These experimental results suggest that the time dependence of D.C. conductivity of rutile single crystal is due to space charge polarization effect; the electrode was Pt which is complete electronic conductor, while the sample was TiO2 which is mixed conductor.

• 한국세라믹학회지
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• 제45권7호
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• pp.375-379
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• 2008

Redox behavior was observed in alkali alkaline earth silicate PDP (Plasma Display Panel) glass melts doped with sulfate and sulfide by square wave voltammetry (SWV). According to voltammograms produced at a temperature range of 1100 to $1400^{\circ}C$ and frequency range of 5 to 1000 Hz, both melts showed the same behavior in which there is one reduction peak at low frequency but another peak at an increase of frequency. Based on the frequency dependence of the peak current, self diffusivity of $S^{4+}$ was determined. Based on the temperature dependence of the peak potential, standard enthalpy (${\Delta}H^0$) and standard entropy (${\Delta}S^0$) for the reduction of $S^{4+}$ to $S^0$ were calculated.

• 한국자기공명학회논문지
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• 제2권1호
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• pp.66-83
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• 1998

Study on spin-rotation relaxation of nuclear spins located on a methyl group can reveal valuable dynamic information related to the internal rotation of methyl group itself. Toward this end we have measured methyl carbon-13 spin-rotation of methyl group itself. Toward this end we have measured methyl carbon-13 spin-rotational relaxation rate in toluene and 2-chloro-p-xylene over the temperature range of 179-363K. To interpret the temperature dependence of measured spin-rotational relaxation rate we have revised the temperature dependence of measured spin-rotational relaxation rate we have revised the expression derived thus far by other authors and reproduced experimental data on the basis of the newly derived expression. The results confirmed that our expression leads to better agreement with experimental data than the previous one over observed temperature range, especially at high temperature.

• 대한수학교육학회지:학교수학
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• 제1권2호
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• pp.401-415
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• 1999

In this paper, 'relations of proportion are used in the introduction of function concept' in 7-first stage of 7th mathematics curriculum is focused. Under the assumption that above statement means dependence-centered view in the teaching of function, the contents of function In 7-first stage is interpreted. Some issues are critically contemplated, And, finally, statement of using relations of proportion in the introduction of function concept is interpreted as dependence-centered view in the teaching of function. Conclusions are as follows: (1) symbol y= f(x) is not inevitable. (2) Term 'codomain' must not be used. (3) Term 'range of x' and 'range of y' must be used. (4) Term 'independent variable' and 'dependent variable' must be used.

• Journal of Magnetics
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• 제2권4호
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• pp.135-137
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• 1997

We report the salient features of the magnetic properties of amorphous TM70Cr5Si10B15(TM=Fe, Co, Ni) alloys. The temperature dependence of magnetization for amorphous ribbons were measured by a SQUID and a VSM from 5 K to 700 K under an external field of 10 kOe. Except TM70Cr5Si10B15 that shows a paramagnetic behaviour, both Fe and Co based amorphous alloys show a typical ferromagnetic thermo-magnetization curves. For these two ferromagnetic alloys, the saturation magnetization in the temperature range from 5 K to about 0.4 Tc can be descrived by the Bloch relation, Ms (T)=Ms(0) [1-BT3/2-CT5/2]. The spin wave stiffness constants and the range of exchange interaction were analyzed from the magnetization behaviour. The variation of the magnetic properties are discussed and compared with the composition of the alloys.

• Current Optics and Photonics
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• 제2권3호
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• pp.286-290
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• 2018

We investigated the dependence of the retardation dispersion on the polarization direction of ultraviolet (UV) light during the photopolymerization of self-organized smectic reactive mesogen (RM) molecules. RM retarder film that was photopolymerized with UV light linearly polarized parallel to the layer plane showed negative dispersion (ND) of retardation for a wide range of UV polymerization temperatures. On the other hand, film that was photopolymerized with unpolarized UV light showed negative dispersion in a narrow range of UV polymerization temperatures. With a certain UV polymerization temperature, the dispersion of retardation was converted from positive to negative, depending on the UV polarization.

• 한국세라믹학회지
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• 제31권4호
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• pp.436-447
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• 1994

ZnO transparent conducting thin film, which is a strong candidate for a transparent electrical contact in optoelectronic devices, was prepared by the vapour spraying method on the slide glass in nitrogen ambient at the atmospheric pressure. The structural, optical and electrical properties of films show a strong dependence on substrate temperature, and the optimum range of deposition temperature existed to obtain TCO(Transparent Conducting Oxide) films. At the higher temperatures, milky films were obtained. In such optimum range, the bandgap in ZnO films was determined from the spectral dependence of absorption coefficient and electrical characteristics were characterized with by the Hall mobility and carrier concentration.

• Journal of Magnetics
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• 제18권3호
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• pp.221-224
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• 2013

Electron paramagnetic resonance (EPR) spectra of $Mn^{2+}$ impurity ion in Stoichiometric $LiNbO_3$ single crystal (SLN) was investigated with an X-band EPR spectrometer in the temperature range of 3 K~296 K. The intensity of EPR spectrum of $Mn^{2+}$ ion was increased to 20 K and decreased again below 20 K as the temperature decreases. The zero-field splitting parameter D decreased as the temperature increases. It was suggested that $Mn^{2+}$ ion substitute for $Nb^{5+}$ ion instead of $Li^+$ ion. No changes for hyperfine interaction of $Mn^{2+}$ ion was obtained in the temperature range of 3 K~296 K.

• 디지털콘텐츠학회 논문지
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• 제16권3호
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• pp.463-470
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• 2015

최근 개인선량계로 사용이 증가하고 있는 수동형 선량계인 OSLD와 능동형 선량계인 EPD의 상대 반응도(relative response), 측정 불확도(uncertainty of measurement)를 계산하여 방향의존성(angular dependence)을 비교, 분석하였다. OSLD는 수평, 수직방향의 $0^{\circ}{\sim}{\pm}90^{\circ}$ 범위에서 평균 상대 반응도는 0.97, 0.95의 작은 변화를 보였고 방향의존성에 대한 불확도는 0.65, 0.62로 전체 불확도에 미치는 영향은 미미한 것으로 판단되었다. EPD는 $0^{\circ}{\sim}{\pm}60^{\circ}$ 범위에서 수평, 수직방향 평균 상대 반응도는 0.94, 0.97로 확인되어 IEC 61526 규정을 만족하였다. 방향의존성에 대한 불확도는 수평, 수직방향에서 0.44, 0.40로 전체 불확도에 미치는 영향은 미미하였다. 그러나 수평방향에서 $+90^{\circ}$, $-90^{\circ}$ 방향의 상대 반응도는 0.60, 0.37이고 수직방향에서 $+90^{\circ}$ 방향의 반응도는 0.06으로 반응도의 큰 변화를 관찰할 수 있었다. OSLD의 방향 의존성은 $0^{\circ}{\sim}{\pm}90^{\circ}$ 범위까지 EPD에 비해 우수하였으며 EPD의 경우 구조적 특징으로 반응도가 급변하는 특정방향이 존재하였다. 따라서 수동형선량계와 보조선량계의 병행사용이 개인피폭선량측정의 정확도를 기할 수 있을 것으로 판단된다.

• Advanced Composite Materials
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• 제18권3호
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• pp.265-285
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• 2009

Off-axis compressive deformation behavior of a unidirectional CFRP laminate at high temperature and its strain-rate dependence in a quasi-static range are examined for various fiber orientations. By comparing the off-axis compressive and tensile behaviors at an equal strain rate, the effect of different loading modes on the flow stress level, rate-dependence and nonlinearity of the off-axis inelastic deformation is elucidated. The experimental results indicate that the compressive flow stress levels for relatively larger off-axis angles of $30^{\circ}$, $45^{\circ}$ and $90^{\circ}$ are about 50 percent larger than in tension for the same fiber orientations, respectively. The nonlinear deformations under off-axis tensile and compressive loading conditions exhibit significant strain-rate dependence. Similar features are observed in the fiber-orientation dependence of the off-axis flow stress levels under tension and compression and in the off-axis flow stress differential in tension and compression, regardless of the strain rate. A phenomenological theory of viscoplasticity is then developed which can describe the tension-compression asymmetry as well as the rate dependence, nonlinearity and fiber orientation dependence of the off-axis tensile and compressive behaviors of unidirectional composites in a unified manner. It is demonstrated by comparing with experimental results that the proposed viscoplastic constitutive model can be applied with reasonable accuracy to predict the different, nonlinear and rate-dependent behaviors of the unidirectional composite under off-axis tensile and compressive loading conditions.