• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.536-540
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• 2007

The Ce-doped YAG(Yttrium Aluminum Garnet, $Y_3Al_5O_{12}$) phosphor powders were synthesized by combustion method. The luminescence, formation process and structure of phosphor powders were investigated by means of XRD, SEM and PL. The XRD patterns show that YAG Phase can form through sintering at $1000^{\circ}C$ for 2 h. This temperature is much lower than that required to synthesize YAG phase via the conventional solid state reaction method. There were no intermediate Phases such as YAP(Yttrium Aluminum Perovskite, $YAlO_3$) and YAM(Yttrium Aluminum Monoclinic, $Y_4Al_2sO_9$) observed in the sintering process. The powders absorbed excitation energy in the range $410{\sim}510\;nm$. Also, the crystalline YAG:Ce showed broad emission peaks in the range $480{\sim}600\;nm$ and had maximum intensity at 528 nm.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1407-1409
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• 2003

The results of investigations of $Ag_2Te$ crystal is presented. $Ag_2Te$ crystal was grown by the Bridgman method. The $Ag_2Te$ crystal was an monoclinic structure with lattice constance a = 8.1686, b=9.0425, c=8.0065. Hall effect shows a n-type conductivity in the $Ag_2Te$ crystal. The electrical resistivity values was $1.080e^{-3}cm$ and electron mobility was $-5.4810^{3}cm^{2}$/Vsec at room temperature(RT).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.101-101
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• 2015

Photoelectrochemical water splitting is considered as a promising method of transforming solar energy into chemical energy stored in the type of hydrogen. An n-type $WO_3$ semiconductor is one of the most promising photoanodes for hydrogen production from water splitting. Films annealed at lower temperatures consisted of amorphous, whereas films annealed above $500^{\circ}C$ comprised solely of monoclinic $WO_3$. In this study, we observed photoactivity of $WO_3$ as increasing thickness of $WO_3$. And it shows good photoacivity as thickness increases. Also we tried to improve photoactivity through surface modification and bulk modification by using hydrogen treatment and conducting polymer. The photocurrent was measured in potentiostatic method with the three electrode system. A Pt wire and Ag / AgCl electrode were used as the counter electrode and the reference electrode, respectively. photocurrent-time (I-T) curve was measured at a bias potential of 0.79 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.31-36
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• 2002

In this work $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}:Co^{2+}$ single crystals were grown by the chemical transport reaction method and the structure of $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}:Co$ single crystals were monoclinic structure. The temperature dependence of optical energy gap was fitted well to Varshni equation. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gap.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.527-531
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• 2016

In this study, p-type thin film transistors consisting of CuO channels were fabricated by sol-gel process, with copper (II) acetate monohydrate precursors. At $500^{\circ}C$, the deposited films were fully converted into monoclinic phase CuO. The fabricated CuO thin film transistors deliver field effect mobility in saturation regime of $0.015cm^2/Vs$, and $I_{on}/I_{off}$ of ${\sim}10^3$. The degradation of the performance of the fabricated CuO thin film transistor caused by the exposure to air has been studied.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.298-303
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• 2000

The 3 mol% yttria stabilized zirconia (3-Y PSZ) powder was heat treated at 50 0$^{\circ}C$ to evaporate the polymer binder and stabilize the tetragonal phase. The wear experiments were carried out on a ring-on-plate type reciprocating wear tester at selected temperatures with in the range room temperature to 600$^{\circ}C$ The results show that the heat treatment of powder decreases the wear rate due to the reduction of microcracks and pores in coatings and the stabilization of the tetragonal phase. Powder heat treatment enhanced the quality of the coating layer by removing remnant gases during coating process and the powder heat treatment at which tetragonal phase is stable diminished phase ratio of monoclinic. These two effects improved wear resistance characters.

• Journal of the Mineralogical Society of Korea
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• v.4 no.1
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• pp.51-55
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• 1991

Transmission electron microscopic study including single particle electron diffraction and morphological observation using replica and thin section was carried out for the Sancheong halloysite. Halloysite tube generally consists of inner circular and outer polygonal leaves. Primary triangular or concave voids are found between inner and outer leaves. Crosssection of halloysite tubes whose diameters are smaller than 500${\AA}$ are generally circular, whereas those larger than 500${\AA}$ are polygonal. Electron diffraction pattern of thick polygonal halloysite tube shows that it has a 2-layer monoclinic structure as suggested by previous workers.

• Journal of the Mineralogical Society of Korea
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• v.3 no.2
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• pp.65-71
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• 1990

Compositions and thermal changes of pyrrhotites from Ohtani and Uljin mines were examined by Arnold's method and DTA analysis. The results are as follow: 1) The compositions of hexagonal type pyrrhotite are in some range from 47.23-47.42 atom.% Fe in the Ohtani mine, and 47.40-47.64 atom.% Fe in the Uljin mine. 2) The compositions of hexagonal pyrrhotite with exsoluted lamellae of monoclinic pyrrhotite are in 47.35-47.50 atom.% Fe in the Ohtani mine, and 47.15-47.40 atom.% Fe in the Uljin mine. This fact does not agree with phase diagrams of Fe-S system shown by Nakazawa and Morimoto(1970) and Sugaki and Shima(1977). 3) DTA data show two endothermic peak corresponding to ${\gamma}$ and $\beta$ transformation. Sturctural conversions from order(intermediate) to disorder(high) forms occur at about $300^{\circ}C$ for hexagonal type and further lower temperature with increasing Fe-content.

• Journal of the Korean institute of surface engineering
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• v.40 no.4
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• pp.180-184
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• 2007

A new zirconium alloy, low-Sn Zircaloy-4 was investigated to see the effects of high pressure steam on the oxidation at high temperatures. High pressure steam turned out to enhance the oxidation at high temperatures below $1000^{\circ}C$. The oxide layer groved to deviate from the uniform layer under high steam pressures, and usually cracks were found at the thicker parts in the oxide layer. High pressure steam seems to destabilize the tetragonal oxides near the metal layer, and the monoclinic oxides transformed from the destabilized tetragonal oxides are structurally not sound, resulting in enhanced oxidation under high pressure steam.

• Bulletin of the Korean Chemical Society
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• v.5 no.1
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• pp.23-26
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• 1984

The crystal structure of phthalylsulfacetamide, one of the long-acting 'sulfa' drugs, has been determined by the X-ray diffraction methods. The crystal is monoclinic with cell dimensions of a = 7.980(3), b = 12.784(2), c = 18.064(7) ${\AA}$ and ${\beta}$= $112.94(2)^{\circ}$, space group $P2_1$/c and Z = 4. The structure was solved by the direct methods and refined to R = 0.048. The sulfonylacetamide moiety is folded with respect to the central phenyl ring and the benzamide and benzoyl planes are nearly perpendicular to each other. This conformation is consistent with those of the relevant molecules containing the corresponding moieties. All of the molecules in the crystal lattice are connected by a three-dimensional hydrogen bonding network.