• Journal of the Korean Chemical Society
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• v.46 no.4
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• pp.336-345
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• 2002

In this study, we have screened $Eu^{3+}$- and $Tb^{3+}$-activated candidate phosphors for PDP in the sys-tems of CaO-Gd$_2$O$_3$-Al$_2$O$_3$ by combinatorial chemistry and investigated the synthetic temperature, optimum com-position and luminescent properties about the candidate phosphors. To construct the emission intensity library by VUV PL, we have synthesized 210 different compositional samples using a polymerized-complex method. Good luminescent samples were identified by X-ray diffraction method. $Ca_$\alpha$$G$d_{0.95-$\alpha$-$\beta$}Al_$\beta$O_$\delta$$ : Eu(0.02< $\alpha$+$\beta$ <0.04) phos-phors screened as a red phosphor have good color purity than commercial phosphor. In the candidate phosphors of CaGdAl$_3O_7$ : Tb, Ca$Al_{12}O_{19}$ : Tb, Gd$_4$Al$_2O_9$ : Tb, and Gd$_3Al_5O_{12}$ : Tb CaGdAl$_3O_7$ : Tb, and Ca$Al_{12}O_{19}$ : Tb have shorter decay time than commercial phosphor.

• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.410-416
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• 1999

The reactivity of three kinds of spinels which CaO-Al2O3-SiO2 slag was investigated in terms of mineral phases and microstructures. New crystal products were not formed by reaction of 12CaO.7Al2O3 in the slag with spinels and free MgO components was preferenctially dissolved into slag for MgO-rich spinel and stoichiometric spinel. Meanwhile mineral phase was changed from 12CaO.7Al2O3 to CaO.Al2O3 to CaO.2Al2O3 finally to CaO.6Al2O3 having high melting point for Al2O3 -rich spinel. The Fe-oxide component of the slag was taken up by only stoichiometric spinel grains within the spinel clinker and the trapped amount of Fe-oxide was independent of MgO content of MgO in spinel clinker the more th resistance to slag corrosion but the less resistance to slag penetration.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.836-837
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• 2005

In order to enhance discharge efficiency of Plasma Display Panel (PDP), we used an electride as electron emission layer for PDP during PDP discharge process. As the electride used in this study, $12CaO7Al_2O_3$, has low work function, it is expected to yield high electron emission during glow discharge process. $12CaO7Al_2O_3$ powder was synthesized from $CaCO_3$ and $Al(OH)_3$ powder and Ca treated for realization of electride characteristics. The $12CaO7Al_2O_3$ powder was coated on the surface of dielectric layer of PDP and discharge characteristics of electride material were evaluated.

• Korean Journal of Materials Research
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• v.13 no.12
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• pp.785-790
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• 2003

We have synthesized some phosphors in the system $CaO-Y_2$$O_3$-$Al_2$$O_3$by combinatorial polymerized-complex method. Composition and synthetic temperature of phosphors in the library was screened from the emission intensities of individual samples under VUV excitation. In $Tb^{ 3＋}$-activated $CaO-Y_2$$O_3$-$Al_2$$O_3$, green phosphors showing good intensity were found to be X$O_3$$O_{7}$, CaYA1O$_4$, YA1O$_3$, $Y_3$$Al_{5}$$O_{12}$, $Y_4$$A1_2$$O_{9}$ .

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.933-938
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• 2004

The clinkerbility and the behaviour of formation of $3CaO{\cdot}Al_{2}O_3$ were studied using the mixture of waste oyster shell and spent oil-refining catalyst mainly by the mineral and microstructural observation. By virtue of the formation of $12CaO{\cdot}7Al_{2}O_3$ at relatively low temperature and its successive reaction with CaO, the $3CaO{\cdot}Al_{2}O_3$ clinkers were formed easily without affection of minor constituents contained in oyster shell. Thus clinkers were formed at $1400^{\circ}C$ directly but began to melt incongruently at higher temperature above that. Aluminium hydroxide, however, was not desirable as an aluminous raw materials of the clinker because rapid melting occurs before $3CaO{\cdot}Al_{2}O_3$ forms main clinker mineral.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.238-239
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• 2018

This paper presents the synthesis results of CaO-Al₂O₃ system clinker using the CaCO₃ and the Al₂O₃ according to the synthesis methods dependent on the temperature. The purpose of this study is the formation of the CaO-Al₂O₃ system clinker containing high ratio of CaO·2Al₂O₃ (CA₂). The maximum sintering temperature for the synthesis of CaO-Al₂O₃ compounds was 1250℃, 1300℃ and 1400℃. The CaO-Al₂O₃ compounds was sintered at the maximum sintering temperature for three hours. After sintering, the compounds was analyzed using X-ray diffraction method. The 12CaO·7Al₂O₃ (C1₂A₇) and CaO·Al₂O₃ (CA) increased as elevating the maximum sintering temperature whereas the CA₂ decreased. Especially, at the 1250℃ of maximum sintering temperature, the un-reacted CaO and Al₂O₃ was identified.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.150-155
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• 2006

제강공정에서 발생되는 $CaO-Al_{2}O_{3}-SiO_{2}$계 조성을 갖는 2 차 정련슬래그 (래들 슬래그)를 이용하여 하수슬러지용 고화재개발 및 하수슬러지 고화체의 물성에 관한 연구를 수행하였다. 래들슬래그는 냉각과정에서 분화되는 성질이 있어 냉각후 분말상의 슬래그가 만들어진다. 분말상 슬래그의 주 결정상은 $12CaO{\cdot}7Al_{2}O_{3}$ 및 $2CaO{\cdot}SiO_{2}$로 구성되어 있다. $12CaO{\cdot}7Al_{2}O_{3}$ 상은 속경성 시멘트의 특징이 있다. 또한 $CaSO_{4}$와 혼합사용시 ettringite 상을 형성시켜 하수슬러지의 함수율 저감효과 및 강도발현 효과가 우수한 결과를 얻었다. $Cl^{-}$ 이온의 고정화면에서는 고화재중 래들슬래그의 혼합비가 높을수록 고화체 구조내에 $Cl^{-}$ 이온이 고정화되어 용출량은 감소하였다. 고화재로서 제강부산물을 사용하기 때문에 경제성이 있으며, $Cl^{-}$ 이온 함량이 높은 하수슬러지 고화재로서의 재활용이 기대된다.

• Journal of the Korean Applied Science and Technology
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• v.27 no.4
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• pp.421-426
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• 2010

The transesterification of rapeseed oil, soybean oil, and mixed fat were conducted at $65^{\circ}C$ with $Al_2O_3$-supported CaO, 0.8 wt% KOH, 1 wt% NaOH and mixed catalyst. The overall conversion(%) of rapeseed oil indicated to be 96% at the 12:1 molar ratio of methanol to oil, 8 wt% CaO and 2 wt% water. The pH ranges of biodiesel for mixed fat using four catalysts and for three fats using 8wt% CaO were 7.3-9.1, 7.3-7.5, respectively. The volumes of water needed to wash biodiesel from rapeseed oil using 0.8 wt% KOH and 8 wt% CaO were 15 mL and 3 mL.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.836-839
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• 2003

We have synthesized some phosphors in the system $CaO-Y_{2}O_3-Al_{2}O_{3}$ by combinatorial polymerized-complex method. Composition and synthetic temperature of phosphors in the liblary was screened from the emission intensities of individual samples under VUV excitation. In $Tb^{3+}$-activated $CaO-Y_{2}O_3-Al_{2}O_{3}$, green phosphors showing good intensity were found to be $CaYAl_{3}O_{7}$, $CaYalO_{4}$, $YAlO_{3}$, $Y_{3}Al_{5}O_{12}$, $Y_{4}Al_{2}O_{9}$, $Ca_{3}Al_{2}O6$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.3
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• pp.103-106
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• 2022

The effect of Al₂O₃ on isokom temperatures in soda-lime glass is estimated by comparing calculated isokom temperatures using viscosity model proposed by Lakatos. Substitution of SiO₂ with Al₂O₃ by 0.5 mol% raises the isokom temperatures by 3.1, 3.3, 3.6 and 7.2℃ at the viscosity of log η = 12.3, 10, 6.6 and 1 (Pa·s), respectively. Meanwhile, replacing 0.5 mol% of CaO with Al₂O₃ raises the isokom temperatures by 1.6, 2.3, 4.1 and 17.7℃ at the viscosity of log η = 12.3, 10, 6.6 and 1 (Pa·s), respectively.