• 한국광학회지
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• 제6권3호
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• pp.173-177
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• 1995

칼날주사방법을 이용한 CCD의 MTF 측정장치를 제작하고 일차원 CCD의 MTF특성을 측정하였다. 주사방향에 수직인 직선과 칼날이 이루는 각도에 따른 CCD MTF 측정값의 변화는 $1^{\circ}$ 미만의 작은 각도변화에 의해서도 MTF값이 크게 변함을 알 수 있었으며 CCD의 MTF 측정값은 간섭필터와 텅스텐 필라멘트가 조합된 파장에 따라 다른 값을 나타내었다. 또한 광원의 색온도 변화에 의한 CCD의 MTF특성과 CCD 화소들의 균일성을 조사하였다.

• 한국전기전자재료학회논문지
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• 제20권6호
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• pp.527-530
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• 2007

[ $SrTiO_3$ ] red phosphors doped with Pr, Er and Al were synthesized by solid state reaction method. Three emission peaks in photoluminescence spectra of the $SrTiO_3:Eu$ Phosphors were observed at 583 nm, 610 nm and 685 nm. The emission peaks in the $SrTiO_3:Eu$ phosphors were associated with charge-transfer states. The decrease of photoluminescence intensity in $SrTiO_3:Eu,Al$ phosphors with doping Al ions was interpreted by the change of charge-transfer states.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.145.1-145.1
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• 2013

A prerequisite for the development of graphene-based field effect transistors (FETs) is reliable control of the type and concentration of carriers in graphene. These parameters can be manipulated via the deposition of atoms, molecules, and polymers onto graphene as a result of charge transfer that takes place between the graphene and adsorbates. In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.27-28
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• 2015

In this paper a high efficiency wireless on-board charger for Electric Vehicle (EV) is proposed and the theoretical analysis based on the two-port network model to come up with suitable design for the battery charge application is presented. The proposed Wireless Power Transfer (WPT) method has adopted four-coil system with air core and its superior performance is proved by comparing it to the conventional two-coil system by the mathematical analysis. In addition, since the proposed WPT converter is able to operate at an almost constant frequency regardless of the load, CC/CV charge of the battery can be simply implemented. A 6.6kW prototype is implemented with 20cm air gap to prove the validity of the proposed method. The experimental results show that the dc to dc conversion efficiency of the proposed system achieves 97.08% at 3.7 kW.

• Bulletin of the Korean Chemical Society
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• 제16권10호
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• pp.972-976
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• 1995

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

• Bulletin of the Korean Chemical Society
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• 제9권6호
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• pp.394-398
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• 1988

Unusually high reactivity was found in peptide bond formation between p-nitrobenzophenone oxime resin (I) ester and amino acid 4-(methylthio)phentyl (MTP) esters. A charge-transfer complex between the two phenyl rings of the oxime resin (I) and the incoming amino acid MTP esters was considered to be responsible to accelerate the aminolysis reaction of the peptide oxime resin ester. Several di-, tri-, and pentapeptide fragments for preparing enkephalin and glutathione oligomers were successfully prepared in short times.

• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.613-620
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• 1992

The solvent-dependent photophysical properties of 2-biphenylcarboxylic acid (2BPCA) and 4-biphenylcarboxylic acid(4BPCA), which have a pre-twisted conformation in the ground state, have been investigated. The fluorescence spectra of 4BPCA show vibrational structure with a non-mirror image to the absorption spectra in nonpolar solvent while those of 2BPCA show no structure even in nonpolar solvents. As the solvent polarity increases, the fluorescence spectra become diffuse and broad with a strong red shift resulting in the large Stokes shift. The large fluorescence Stokes shift of BPCA's in polar solvent is also partially due to an intramolecular charge transfer (ICT) interaction in the excited state, as demonstrated by the large dipole moment in the excited state (7.6-10.6 D). The fluorescence decay behaviors of BPCA's (decay-times and their pre-exponential factors) also depend on solvent polarity in agreement with the solvent-dependent properties of the steady-state fluorecence. The data have been discussed in terms of change in the excited-state potential energy surface with respect to change of the dihedral angle of biphenyl moiety.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.225-234
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• 1993

As an application of the cluster orbitals proposed previously, nickel-, palladium-, and platinum-hydrogen systems are studied. Density of states, projected density of states, HOMO levels, and stabilization energies are calculated and compared with those obtained by extended Huckel method for small clusters. These calculations are extended to large clusters to find the size dependence of several physical quantities. Reduced overlap populations are also calculated to clarify the charge transfer phenomena reported earlier. The calculated physical quantities show no dependence on the cluster size. It is also found that the charge transfer occurs due to the intrinsic character of palladium, not due to the edge effect which may be present in small clusters.

• 한국재료학회지
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• 제26권12호
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• pp.696-703
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• 2016

In this study, we intensively investigated the effect of conductive additive amount on electrochemical performance of organic supercapacitors. For this purpose, we assembled coin-type organic supercapacitor cells with a variation of conductive additive(carbon black) amount; carbon aerogel and polyvinylidene fluoride were employed as active material and binder, respectively. Carbon aerogel, which is a highly mesoporous and ultralight material, was prepared via pyrolysis of resorcinol-formaldehyde gels synthesized from polycondensation of two starting materials using sodium carbonate as the base catalyst. Successful formation of carbon aerogel was well confirmed by Fourier-transform infrared spectroscopy and $N_2$ adsorption-desorption analysis. Electrochemical performances of the assembled organic supercapacitor cells were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. Amount of conductive additive was found to strongly affect the charge transfer resistance of the supercapacitor electrodes, leading to a different optimal amount of conductive additive in organic supercapacitor electrodes depending on the applied charge-discharge rate. A high-rate charge-discharge process required a relatively high amount of conductive additive. Through this work, we came to conclude that determining the optimal amount of conductive additive in developing an efficient organic supercapacitor should include a significant consideration of supercapacitor end use, especially the rate employed for the charge-discharge process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.351-354
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• 2000

AC impedance of LiM $n_2$ $O_4$ and LiM $g_{0.1}$M $n_{1.9}$ $O_4$ samples have been studied at various temperature with charge-discharge test. AC impedance of LiM $n_2$ $O_4$ measured at -2$0^{\circ}C$, room temperature and 5$0^{\circ}C$ revealed that initial impedance before charge-discharge test was gradually decreased and become small by becoming law temperature. It indicates that the Li ion diffusion and the transfer resistance of the cathode are related to the temperature of cycling. Impedance at high temperature was suddenly increased because Mn dissolution and decomposition of electrolyte had been increased during cycling, compared to impedance at low temperature. Therefore, charge-discharge capacity was suddenly decreased at high but was slowly at low. In LiM $g_{0.1}$M $n_{1.9}$ $O_4$, impedance and capacity were stability at room temperature than there at 5$0^{\circ}C$, too. Initial impedance at 5$0^{\circ}C$ before charge-discharge test was small and impedance was suddenly increased during cycling than that at room temperature.ure.ure.