• 한국결정성장학회지
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• 제7권2호
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• pp.315-323
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• 1997

수직승화방법을 이용하여 시료의 용융점 미만의 온도에서 CdS 단결정을 성장하였다. 분말법을 이용한 X-ray 실험으로부터 구한 CdS 단결정의 격자상수 값은 $a_0=4.139\AA$, $c_0=6.719\AA$이었다. 성장된 CdS 단결정과 CuCl 용액을 사용하여 $Cu_2$S/CdS 태양전지를 제작한 후 2분 동안 공기중에서 $250^{\circ}C$로 열처리한 후 light-to-dark J-V cross over effect를 측정하였다. 측정된 Voc, Jsc, Vop와 fill factor값은 각각 0.40 volt, $4.2mA/\textrm{cm}^2$, 0.31 volt,$3.8mA/\textrm{cm}^2$, 0.68이었으며, 효율은 3.8 %를 나타내었다. 제작된 태양전지의 spectral response는 광발광 실험으로부터 498 nm (2.49eV)와 585 nm (2.12 eV)에서 그 peak가 나타남을 확인하였다.

• Journal of Magnetics
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• 제17권2호
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• pp.86-95
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• 2012

This study investigated the effects of adding a third alloying element, Ni, to create $Fe_{70-x}Pd_{30}Ni_x$ (x = 2, 4, 6, 8 at.% Ni) ferromagnetic shape memory alloys (FSMAs). The Ni replaced a portion of the Fe. The $Fe_{70-x}Pd_{30}Ni_x$ alloys were homogenized through hot and cold forging to gain a ~38% reduction in thickness, next they were solution-treated (ST) with annealing recrystallization at $1100^{\circ}C$ for 8 h and quenched in ice brine, and then aged at $500^{\circ}C$ for 100 h. Investigation of the microstructures and magnetostriction indicated that the greater Ni amount in the $Fe_{70-x}Pd_{30}Ni_x$ alloys reduced saturation magnetostriction at room temperature (RT). It was also observed that it was more difficult to generate annealed recrystallization. However, with greater Ni addition into the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys, the $L1_0+L1_m$ twin phase decomposition into stoichiometric $L1_0+L1_m+{\alpha}_{bct}$ structures was suppressed after the $500^{\circ}C$/100 h aging treatment. The result was that the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys maintained a high magnetostriction and magnetostrictive susceptibility (${\Delta}{\lambda}{_\parallel}{^s}/{\Delta}H$) after the alloys were aged at $500^{\circ}C$ for 100 h. This magnetic property of the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys make it suitable for application in a high temperature (T > $500^{\circ}C$) and high frequency environments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.388-388
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• 2010

In this study, Ferroelectric vinylidene fluoride-trifluoroethylene (VF2-TrFE) copolymer films were directly deposited on degenerated Si (n+, $0.002\;{\Omega}{\cdot}cm$) using by spin coating method. A 1~5 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene (VF2:TrFE = 70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers at a spin rate of 2000 ~ 4000 rpm for 2 ~ 30 seconds. After annealing in a vacuum ambient at 100 ~ $200^{\circ}C$ for 60 min, upper aluminum electrodes were deposited by vacuum evaporation for electrical measurement. X-ray diffraction results showed that the VF2-TrFE films on Si substrates had $\beta$-phase of copolymer structures. The capacitance on highly doped Si wafer showed hysteresis behavior like a butterfly shape and this result indicates clearly that the copolymer films have ferroelectric properties. The typical measured remnant polarization ($P_r$) and coercive filed ($E_c$) values were about $5.7\;{\mu}C/cm^2$ and 710 kV/em, respectively, in an applied electric field of ${\pm}$ 1.5 MV/em. The gate leakage current densities measured at room temperature was less than $7{\times}10^{-7}\; A/cm^2$ under a field of 1 MV/cm.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.146-149
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• 2002

The aim of stereotactic radiosurgery(SRS) is to deliver a high dose to a target region and a low dose to critical organ through only one or a few irradiation. To satisfy this aim, optimized irradiating conditions must be searched in the planning. Thus, many mathematical methods such as gradient method, simulated annealing and genetic algorithm had been proposed to find out the conditions automatically. There were some limitations using these methods: the long calculation time, and the difficulty of unique solution due to the different shape of tumor. In this study, optimization protocol using ideal models and data base was proposed. Proposed optimization protocol constitutes two steps. First step was a preliminary work. Some possible ideal geometry shapes, such as sphere, cylinder, cone shape or the combination, were assumed to approximate the real tumor shapes. Optimum variables such as isocenter position or collimator size, were determined so that the high dose region could be shaped to fit ideal models with the arrangement of multiple isocenter. Data base were formed with those results. Second, any shaped real targets were approximated to these models using geometry comparison. Then, optimum variables for ideal geometry were chosen from the data base predetermined, and final parameters were obtained by adjusting these data. Although the results of applying the data base to patients were not superior to the result of optimization in each case, it can be acceptable as a starting point of plan.

• 공업화학
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• 제5권6호
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• pp.998-1008
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• 1994

p-옥시벤조일, iso-나프탈렌, 디메틸 디실록실 그룹으로 이루어진 코폴리에스테르를 모노머 서열을 달리하여 용액중합으로 합성하고 이들의 특성을 비교하였다. iso-나프탈렌 그룹의 naphthalene은 1,4, 1,5, 2,6, 2,7 치환 단위를 사용하였다. 합성된 중합체의 고유점성도는 0.27~0.42dl/g이었고, 2,7-ordered 코폴리에스테르를 제외한 모든 중합체는 양방성 네마틱 액정을 보였다. 중합체를 열처리한 결과는 분자량의 증가와 결정화도의 증가를 가져왔다. 또 ordered코폴리머와 random코폴리머의 열전이 온도, 열안정성, 결정화 거동, 액정성에서 많은 차이가 남을 관찰하였다.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3553-3558
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• 2014

The reduced graphene oxide(rGO)/aluminum phosphate($AlPO_4$)-coated $LiMn_{1.5}Ni_{0.5}O_4$ (LMNO) cathode material has been developed by hydroxide precursor method for LMNO and by a facile solution based process for the coating with GO/$AlPO_4$ on the surface of LMNO, followed by annealing process. The amount of $AlPO_4$ has been varied from 0.5 wt % to 1.0 wt %, while the amount of rGO is maintained at 1.0 wt %. The samples have been characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The rGO/$AlPO_4$-coated LMNO electrodes exhibit better cyclic performance compared to that of pristine LMNO electrode. Specifically, rGO(1%)/$AlPO_4$(0.5%)- and rGO(1%)/$AlPO_4$(1%)-coated electrodes deliver a discharge capacity of, respectively, $123mAhg^{-1}$ and $122mAhg^{-1}$ at C/6 rate, with a capacity retention of, respectively, 96% and 98% at 100 cycles. Furthermore, the surface-modified LMNO electrodes demonstrate higher-rate capability. The rGO(1%)/$AlPO_4$(0.5%)-coated LMNO electrode shows the highest rate performance demonstrating a capacity retention of 91% at 10 C rate. The enhanced electrochemical performance can be attributed to (1) the suppression of the direct contact of electrode surface with the electrolyte, resulting in side reactions with the electrolyte due to the high cut-off voltage, and (2) smaller surface resistance and charge transfer resistance, which is confirmed by total polarization resistance and electrochemical impedance spectroscopy.

• 융합정보논문지
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• 제10권6호
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• pp.77-86
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• 2020

매우 얇고 다공성 비인화성 와이퍼 용지를 아인산 수용액 처리에 의해 준비되었다. H₃PO₃ 처리는 와이퍼 용지의 난연성을 불연성 수준으로 개선시켰다. 열중량 분석 결과 700℃에서 잔량이 50%까지 증가했다. 이것은 본 실험과 같은 아인산 처리가 셀룰로오스 사슬의 탈수를 돕고, 연소중에 차르(char)와 유사한 구조의 형성을 촉진한다는 것을 의미한다. FT-IR과 X선 광전자 분광학에서는 H₃PO₃의 일부분은 셀룰로오스 사슬의 작용기와 반응하는 것으로 보였다. 반응한 아인산은 셀룰로오스의 체인의 탈수를 촉진하고, 차르와 같은 구조의 형성을 도와 와이퍼 용지의 난연성을 향상시킨다.

• 한국재료학회지
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• 제13권12호
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• pp.819-824
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• 2003

The Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy exhibited excellent elongation by the new thermomechanical treatment (TMT) process; solution treatment and furnace cooling\longrightarrowhot and cold rolling and then annealing for short time. Tensile test at high temperature from 430 to $500^{\circ}C$ has been performed with various strain rates using for the Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy obtained by the TMT process. The elongation of the Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc was 550% tensile tested at $470^{\circ}C$ temperature and 2.2 $\times$ $10^{-3}$ $s^{-1}$ strain rate. The m value of Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy deformed 85% increased from 0.33 to 0.46 with increasing total elongation. This new TMT process was very simple and easy to make the sheets in the company.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.54-57
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• 2003

[ $HfO_xN_y$ ] films using a hafnium tertiary-butoxide $(Hf[OC(CH_3)_3]_4)$ in plasma and $N_2$ ambient were prepared to improve the thermal stability of hafnium-based gate dielectrics. A 10% nitrogen incorporation into $HfO_2$ films showed a smooth surface morphology and a crystallization temperature as high as $200^{\circ}C$ compared with pure $HfO_2$ films. The $TaN/HfO_xN_y/Si$ capacitors showed a stable capacitance-voltage characteristics even at post-metal annealing temperature of $1000^{\circ}C$ in $N_2$ ambient and a constant value of 1.6 nm EOT (equivalent oxide thickness) irrespective of an increase of PDA and PMA temperature. Leakage current densities of $HfO_xN_y$ capacitors annealed at PDA temperature of 800 and $900^{\circ}C$, respectively were approximately one order of magnitude lower than that of $HfO_2$ capacitors.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.158-158
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• 2009

The electrophoretic deposition(EPD) technique with a wide range of novel applications in the processing of advanced ceramic materials and coatings, has recently gained increasing interest both in academic and industrial sector not only because of the high versatility of its use with different materials and their combinations but also because of its cost-effectiveness requiring simple apparatus. Compared to other advanced shaping techniques, the EPD process is very versatile since it can be modified easily for a specific application. For example, deposition can be made on flat, cylinderical or any other shaped substrate with only minor charge in electrode design and positioning[1]. The synthesis of the nano-sized Ce0.2Sm0.8O1.9(SDC)particles prepared by aurea based low temperature hydrothermal process was investigated in this study[2].When we made the SDC nanoparticles, changed the time of synthesis of the SDC. The SDC nanoparticles were characterized with field-emission scanning electron microscope(FESEM), energy dispersive X-ray analysis(EDX), and X-ray diffraction(XRD). And also we researched the results of our investigation on electrophoretic deposition(EPD) of the SDC particles from its suspension in acetone solution onto a non-conducting NiO-SDC substrate. In principle, it is possible to carry out electrophoretic deposition on non-conducting substrates. In this case, the EPD of SDC particles on a NiO-SDC substrate was made possible through the use of a adequately porous substrate. The continuous pores in the substrates, when saturated with the solvent, helped in establishing a "conductive path" between the electrode and the particles in suspension[3-4]. Deposition rate was found to increase its increasing deposition time and voltage. After annealing the samples $1400^{\circ}C$, we observed that deposited substrate.