• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.49.2-49.2
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• 2018

스퍼터링에 의해 증착된 박막 내 기계적 응력 발생 현상을 규명하기 위하여 활발한 이론적, 실험적 접근이 있었으나, 복잡한 플라즈마 증착환경 내에서 다양한 증착 파라미터로 인해 정확한 응력 발생 메커니즘에 대해 아직도 완벽한 규명이 되지 않은 상황이다. 본 연구에서는 몰리브데늄 (Mo)과 텅스텐 (W) 박막을 마그네트론 스퍼터링법을 이용하여 증착 시 발생하는 잔류응력 발생 현상에 대해 논의하겠다. Mo 박막의 경우 증착압력을 2.5 mTorr와 4.1 mTorr로 고정시킨 채 기판 바이어스를 0-250 V 간격으로 변화시킨 결과, 2.5 mTorr에서는 기판바이어스가 증가할수록 압축응력이 증가하는 반면 4.1 mTorr에서는 기판바이어스가 증가할수록 인장응력이 증가하는 것이 확인되었다. 이러한 반대 경향의 잔류응력을 발생시키는 기판 바이어스 효과를 확인하기 위하여 증착 파라미터 변경에 따른 박막 성장 거동 모델을 제시한다. W 박막은 준안정상인 ${\beta}$-상이 증착 초기(2.5 nm)에 형성이 되고, 증착 과정에서 열역학적 안정상인 ${\alpha}$-상으로 상변태 하였다. 상변태에 의한 부피 변화에 따른 잔류응력 발생의 분석을 위하여 X-ray 회절피크의 비대칭성을 분석한 결과 압축응력과 인장응력이 공존하고 있는 것으로 확인되었다. 본 연구결과는 스퍼터링 공정 시 높은 에너지를 가지는 중성화된 Ar과 스퍼터된 원자가 기판과 충돌 시 atomic peening effect에 의해 압축응력이 발생한다는 일반적인 이론과 상충되는 결과로서, Mo 및 W 박막 내 잔류응력 제어를 위한 방안을 제시한다.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.5
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• pp.262-270
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• 2011

Carbide precipitation and dissolution behavior at various temperatures during heat treatment has been studied in STD11 cold working die steel through confocal scanning laser microscopy; dilatometry; and X-ray diffraction analysis. The equilibrium phase diagram and phase fractions with temperature were calculated using a FactSage program. Confocal laser microscopic observation revealed that ${\alpha}$ to ${\gamma}$ transformation temperature is near $800^{\circ}C$; M7C3 carbides melt at $1245^{\circ}C$; and the melting temperature of STD11 is near $1370^{\circ}C$. XRD results indicated that the M23C6 carbides dissolve in the matrix if austenitized at over $1030^{\circ}C$; while the M7C3 carbides remain up to $1200^{\circ}C$ although their amount decreases. The calculated equilibrium phase diagram showed good agreement with experimental results on carbide dissolution and phase transformation temperatures.

• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.709-716
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• 1999

Ceramic is select for an alternative substrate material for high-speed circuits due to its low-thermal expansion. As, in this study, ceramic was prepared by ISG (interlayer sol-gel) process using metal salts and a metal alkoxide as the starting materials. Generally ceramic substrate is used electroless copper plating for the metallization. But it has been indicate weakely the adhesion strength between the substrate and copper layer. Therefore, this research, using the ISG process on the preparation of homogeneous and possible preparation at law temperature fabricated sol solution. Using of the dip coating method was coated for the purpose of giving the anchoring effect on the coating layer and enhancing the adhesion strength between the $Al_2$O$_3$ substrate and copper layer. This study examined primary the characteristic of the sol making condition and differential thermal analysis (DTA) X-ray diffraction (XRD) were mearsured to identify the crystal phase of heat treatment specimens. The morphology of the coated films were studied by scanning electron microscopy(SEM). As a resurt, XRD analysis was obtained patterns of $\alpha$-cordierite after heat-treatment about 2 hours at $1000^{\circ}C$. SEM analysis could have seen a large number of voids on coated film. The more contants of$ Al_2$$O_3$ Wt% was increased the more voids was advanced. Peel adhesion strength has a maximum in the contants of the TEOS:ANE of 1:0.7 mole%. In this case, adhesion strength has been measured 1150gf, peel adhesion strength were about 10 times more than uncoated of the ceramics film.

• Journal of the Korean institute of surface engineering
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• v.44 no.4
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• pp.149-154
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• 2011

Martensitic stainless steel STS 431 has been nitrided by active screen ion nitriding under the various temperature and time. The thickness of diffusion layer, case depth, hardness and composition phases were investigated using field emission scanning electron microscopy (FE-SEM), micro-Vickers hardness tester, X-ray diffraction (XRD) and glow discharge spectroscopy (GDS). It was observed that the thickness of diffusion layer depends strongly on the treatment temperature and time. A sample, which was nitrided at $450^{\circ}C$ for 8hours, was a maximum hardness of Hv0.01 1558 and nitride layer of $70{\mu}m$. As shown in XRD patterns, $\varepsilon(Fe_{2-3}N)$ and expanded martensite (${\alpha}_N$) phases which was saturated with nitrogen solid solution were in the nitrided layer treated at $450^{\circ}C$ for 2 hours. Composition phases of $\varepsilon$ $(Fe_{2-3}N)$ and ${\gamma}'$ ($Fe_4N$) were observed after active screen nitriding at $450^{\circ}C$ for 8 hours.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.140-143
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• 2002

In this study, we prepared ZnO/glass and $ZnO/SiO_{2}/Si$ thin film by Facing Targets Sputtering (FTS) system for Film Bulk Acoustic Resonator (FBAR). When the ZnO thin film applied to piezoelectric thin film, it requires good c-axis preferred orientation. And c-axis orientation has a remarkable difference with preparation conditions. Therefore, c-axis orientation must be significantly evaluated according to changing deposition conditions. Moreover, in order to prepare ZnO thin film with good crystallographic properties and progressive of efficiency of product process, the ZnO thin film should have to prepared as low temperature as possible. In this work, we prepared ZnO thin films on slide glass and $SiO_{2}/Si$ substrate. And the crystallographic characteristics of ZnO thin films on sputtering conditions were investigated by alpha-step and X-ray diffraction.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1119-1123
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• 2002

Nanostructured spinel NiZn ferrites were prepared by the sol-gel method from metal nitrate raw materials. Analyses by X-ray diffraction and scanning electron microscopy showed the average particle size of NiZn ferrite was under 50 nm. The single phase of NiZn ferrites was obtained by firing at 250${\circ}C$, resulting in nanoparticles exhibiting normal ferrimagnetic behavior. The nanostructured $Ni_{1-X}Zn_XFe_2O_4$ (x=0.0∼1.0) were found to have the cubic spinel structure of which the lattice constants ${\alpha}_2$ increases linearly from 8.339 to 8.427 ${\AA}$ with increasing Zn content x, following Vegard's law, approximately. The saturation magnetization $M_s$ was 48 emu/g for x=0.4 and decreased to 8.0 emu/g for higher Zn contents suggesting the typical ferrimagnetism in mixed spinel ferrites. Pure NiZn ferrite phase substituted by Cu was observed before using the additive but hematite phase was partially appeared at $Ni_{0.2}Zn_{0.2}Cu_{0.6}Fe_2O_4$. On the other hand, the hematite phase in this NiZn Cu ferrite was disappeared after using the additive of acethyl aceton with small amount. The saturation magnetization Ms of $Ni_{0.2}Zn_{0.8-y}Cu_yFe_2O_4$(y=0.2∼0.6) as measured was about 51 emu/g at 77K and 19 emu/g at room temperature, respectively.

• Journal of Magnetics
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• v.16 no.4
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• pp.435-439
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• 2011

In this work, we prepared Fe-Ni alloy nanopowders by wire electrical explosion in deionized water and ethanol. Particles size and morphology of the as-synthesized nanoparticles prepared in water and ethanol were observed by transmission electron microscopy. In both cases, the as-synthesized nanoparticles were in nearly spherical shape and their size distribution was broad. The particles prepared in the water were in core-shell structure due to the oxidation of Fe element. X-ray diffraction was used to analyze the phase of the nanopowders. It showed that the nanopowders prepared in water had ${\gamma}$-Fe-Ni solid solution and FeO phase. The samples obtained in ethanol were in two phases of Fe-Ni solid solution, ${\gamma}$-Fe-Ni and ${\alpha}$-Fe-Ni. Bulk samples were made from the as-synthesized nanopowders by spark plasma sintering at $1000^{\circ}C$ for 10 min. Structure of the bulk sample was observed by scanning electron microscope. Magnetic properties of the as-synthesized nanopowders and the bulk samples were investigated by vibrating sample magnetometer. The hysteresis loop of the assynthesized nanopowders and the sintered bulk samples revealed a ferromagnetic characteristic.

• Archives of Pharmacal Research
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• v.3 no.1
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• pp.37-49
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• 1980

Chlorpropamide, $C_{10}H_{13}N_{2}O_{3}SCI$, forms orthofombic crystals of space group $P_{2}_{ 1}2_{1}2_{1}$ with a 9.066 $\pm$ 0.004, b = 5.218 $\pm$ 0.003, c = 26, 604 $\pm$, 0.008 $\AA$, and four molecules per cell. Three dimensional photographic data were collected with Mo-K$\alpha$ radiation. The structure was determined using Patterson, Fourier and Difference syntheses methods and refined by the block-diagonal least-squares methods with anisotropic thermal parameters for all nonhydrogen atoms and isotropic thermal parameters for all hydrogen atomes. The final R value was 0.10 for the 1823 observed independent reflections. The dihedral angle between the planes through the benzene ring and the urea goup is 99$^{\circ}$. The conformational angle formed by the projection of the S-C(1) with that of N(1)-C(7) when the projection is taken along the S-N(1) bond is 76$^{\circ}$. The molecule appears to form with neighbouring molecules two hydrogen bonds, N(1)..H...O(3) and N(2)-H...0(2) of lengths 2.774 and 2.954$\AA$ respectively related by screw diads parallel to the a axis. Adjacent molecules parallel to b and c axis are bound together by van der Wasls forces.

• Korean Journal of Crystallography
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• v.14 no.1
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• pp.16-23
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• 2003

The electronic structure and chemical bonding of β-MnO₂ were theoretically investigated by DV-X/sub α/ (the discrete variation X/sub α/) method. which is a sort of the first principle molecular orbital method using Hatre-Fock-Slater approximation. The calculations on several cluster models having different sizes were carried out for the determination of a model suited for analyzing bulk state. The Mn/sub 15/O/sub 56/ model was selected as a sufficiently suitable model for the calculation of electronic state and chemical bonding by the comparison of the calculated XPS (X-ray photo-electron spectrum) and experimentally measured XPS. By using this model, the electron energy level, the density of state, the bond overlap population, the charge density distribution, and the net ionic transfer between cations and anions were calculated and discussed.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.475-479
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• 2007

Pulsed laser deposition was utilized to grow MnS thin films on c-sapphire substrate using a KrF excimer laser at growth temperatures that ranged from room temperature to $700^{\circ}C$. The results of X-ray diffraction (XRD) and UV-visible spectroscopy were employed to investigate the structural and optical properties of the MnS films. While the growth rate decreased as $T_s$ increased, the overall quality of the film improved. The highest quality MnS film was obtained at $700^{\circ}C$. Variations in the $T_s$ resulted in the MnS films exhibiting different growth mechanisms. The oriented (200) rocksalt MnS film was grown at room temperature. In the case of higher $T_s,\;200{\sim}500^{\circ}C$, the films consisted of mixed phases of rocksalt and wurtzite. The main structure of the films was altered to (111) rocksalt when the temperature was increased to in excess of $600^{\circ}C$. This behavior may very well be the result of elements such as surface energy and atomic arrangement during the growth process. The optical band gap of the obtained ${\alpha}-MnS$ film was estimated to be 3.32 eV.