• 한국결정성장학회지
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• 제10권1호
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• pp.86-90
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• 2000

석탄회를 환경친화적 건설재로 재활용하기 위한 기초연구로서 미연탄소를 함유한 석탄회와 점토의 복합체에 대해 승온패턴에 따른 소결시험을 실시하여 석탄회의 재활용 가능성을 검토하였다. 소결을 위한 승온조작에서 $20^{\circ}C$/min 이상의 승온속도로 가열함에 따라 2.54 cm 크기의 조골재에서 불균질상이 관찰되었고, 최종 소결온도 $1200^{\circ}C$에서는 가스 팽창에 의한 부풀음(bulging), 내부 기공 및 균열이 발생하였다. 따라서 이에 따른 내부 불균질상을 제거할 수 있는 승온패턴을 제안하여 불균질상을 제거하였다. 최종적으로 얻어진 골재의 압축강도는 최소 요구치인 200kg/$\textrm{cm}^2$에 2.5배가 넘는 670~870kg/$\textrm{cm}^2$이었다.

• 한국결정성장학회지
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• 제6권4호
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• pp.648-662
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• 1996

임피던스 스펙트럼을 이용하여 황산 용액에서 glassy carbon과 인조흑연(PVDF 합성 흑연)의 전극표면에 cyclic 분극을 부하 하였을 경우 전극표면에서 나타나는 표면반응에 대하여 조사하여 . 두 재료 표면에서 산소의 산화 혹은 환원과 관련되거나 또는 탄소재료 표면에 화학흡착된 표면작용기(surface functional group)의 변화와 관련되는 것으로 생각되는 산화환원 피크가 potentio-dynamic곡선에서 나타났다. 이러한 전극 표면에서의 표면작용기의 산화환원은 glassy carbon과 PVDF합성 흑연의 임피던스 스펙트럼에도 커다란 영향을 미치는 것으로 나타났다. 또 glassy carbon과 PVDF합성 흑연에서의 임피던스 파라미터는 분극부하에의해 현저한 변화가 나타났다.가 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.101-102
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• 2006

A stoichiometric mixture of evaporating materials for $AgGaS_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films. $AgGaS_2$ mixed crystal was deposited on thoroughly etched semi-Insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $590^{\circ}C$ and $440^{\circ}C$, respectively. The temperature dependence of the energy band gap of the $AgGaS_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.7284 eV-(8.695{\times}10^{-4} eV/K)T^2/(T+332 K)$. After the as-grown $AgGaS_2$ single crystal thin films was annealed in Ag-, S-, and Ga-atmospheres, the origin of point defects of $AgGaS_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.100-101
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• 2008

To obtain the single crystal thin films, $CuGaSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $450^{\circ}C$, respectively. After the as-grown $CuGaSe_2$ single crystal thin films was annealed in Cu-, Se-, and Ga-atmospheres, the origin of point defects of $CuGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{CU}$, $V_{Se}$, $Cu_{int}$, and $Se_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuGaSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $CuGaSe_2$/GaAs did not form the native defects because Ga in $CuGaSe_2$ single crystal thin films existed in the form of stable bonds.

• 통합자연과학논문집
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• 제3권1호
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• pp.54-59
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• 2010

A stoichiometric mixture of evaporating materials for $ZnIn_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $ZnIn_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $ZnIn_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $9.41{\times}10^{16}cm^{-3}$ and $292cm^2/v{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $ZnIn_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $Eg(T)=1.8622eV-(5.23{\times}10^{-4}eV/K)T^2/(T+775.5K)$.

• Korean Chemical Engineering Research
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• 제44권3호
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• pp.289-293
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• 2006

탄산칼슘을 제조하는 연속식 결정화 공정에서 결정의 입도분포에 대한 온도와 교반속도 영향을 연구하였다. 연속식조업에서 용액의 산도 변화는 적었다. 교반속도가 300 RPM 이하, 용액의 온도가 낮으면 탄산칼슘 결정의 부피 평균크기는 안정하였고, 전자현미경 사진 관찰에서 calcite와 aragonite가 만들어졌음을 알 수 있었다

• Restorative Dentistry and Endodontics
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• 제4권1호
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• pp.29-34
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• 1978

The purpose of this study was to measure penetration of dye stuff(5% Methylene blue, Hematoxylin, Crystal violet and Safranin-O) on silicate cement, Adaptic, Hi-pol and unfilled resin. Each filling material was mixed on the mixing pad and the mixed material was inserted with condensation force of 500gr, 1000gr and 2000gr and without condensation force into preformed glass tube (10mm in diameter and 10mm in height). The specimen was stored in the air for 24 hours, then specimen was immersed in various dye solution (5% methylene blue, hematoxin, crystal violet and safranin-O) for different period of time (l hour and 24 hours). These dye-treated specimen was cut horizontally at the middle portion and the dye penetration in cut surface was measured. Following results were obtained. 1. Pentration of various dye was excessive in silicate cement with and without Condensation force. 2. There has been no evidence of dye penetration in unfilled resin. 3. Dye penetration occurced with in 1 hour period and the extending time didn't affect the dye penetration.

• Bulletin of the Korean Chemical Society
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• 제21권8호
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• pp.805-808
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• 2000

Mixed crystal powders based on Cd,Fe, and S have been synthesized by varying the ratio of CdS and $FeS_2in$ order to find a suitable material usefuI for the effectivc conversion of solar energy. Hydrogen gas was evolved only with CdS/Ptby photocatal ytic reaction under white light in an aqueous 1 M sodiumsulfite solution. From electrochemical studies of semiconductor electrodes. itwas shown that the onset potential shifted to the positive direction and that the bandgap energy also decreased as the molar ratio of Fe increased. A hydrogen evolution mechanism in terms of the conduction band potential and hydrogen evolution potential is proposed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.266-272
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• 2002

The stochiometric mixture of evaporating materials for the ZnIn$_2$S$_4$ single crystal thin film was prepared from horizontal furnace. To obtain the ZnIn$_2$S$_4$ single crystal thin film, ZnIn$_2$S$_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100) in the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 610 $^{\circ}C$ and 450 $^{\circ}C$, respectively and the growth rate of the ZnIn$_2$S$_4$ single crystal thin film was about 0.5 $\mu\textrm{m}$/hr. The crystalline structure of ZnIn$_2$S$_4$ single crystal thin film was investigated by photo1uminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of ZnIn$_2$S$_4$ single crystal thin film measured from Hall effect by van der Pauw method are 8.51${\times}$10$\^$17/ cm$\^$-3/, 291 $\textrm{cm}^2$/V$.$s at 293 $^{\circ}$K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the ZnIn$_2$S$_4$ single crystal thin film, we have found that the values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 0.0148 eV and 0.1678 eV at 10 $^{\circ}$K, respectively. From the photoluminescence measurement of ZnIn$_2$S$_4$ single crystal thin film, we observed free excition (E$\_$X/) typically observed only in high quality crystal and neutral donor bound exciton (D$^{\circ}$,X) having very strong peak intensity. The full width at half maximum and binding energy of neutral donor bound excition were 9 meV and 26 meV, respectively. The activation energy of impurity measured by Haynes rule was 130 meV.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.171-174
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• 2004

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnace. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at $630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is $2.1{\mu}m$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $AgGaSe_2$ single crystal thin films measured from Hall effect by van der Pauw method are $4.89{\times}10^{17}\;cm^{-3},\;129cm^2/V{\cdot}s$ at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $AgGaSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_o$ and the crystal field splitting ${\Delta}C_r$ were 0.1762 eV and 0.2494 eV at 10 K, respectively. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition $(E_X)$ observable only in high quality crystal and neutral bound exciton $(D^o,X)$ having very strong peak intensity And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.