• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.49-55
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• 2012

In this paper, the physical properties of lightweight aggregate such as density and water absorption according to addition ratio and type of flux were investigated. When using $Na_2CO_3$ as flux of lightweight aggregate, burnability was available at low burning temperature and water absorption increased. And as increasing addition ratio of $CaCO_3$, NaOH, $Fe_2O_3$, absorption decreased and $CaCO_3$, NaOH, $Fe_2O_3$ were considered improper to use flux of lightweight aggregate because of high dried density. $Na_2SO_4$ was proper to use flux of lightweight aggregate due to dried density $1.35{\sim}1.50g/cm^3$ and lower absorption. When using glass abrasive sludge as flux of lightweight aggregate, dried density and water absorption were in the range of $1.45{\sim}1.55g/cm^3$ and 9~12% respectively. It was indicated that as increasing addition ratio of blast furnace slag powder, density increased whereas absorption decreased. In use of oxidizing slag as flux, artificial lightweight aggregate which have dried density $1.46g/cm^3$, water absorption 8,5 % can be manufactured at 10 % of addition ratio.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.319-324
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• 1999

기존의 고상 반응법에 의해 합성된 YNbO4 : Bi 형광체의 발광특성을 개선하기 위하여 B2O3 융체 첨가법으로 형광체를 합성하고, 빛발광(PL) 및 저전압 음극선발광(CL)을 측정하였다. PL 및 CL 모두 415~440 nm 영역에서 강한 청색 발광 스펙트럼을 나타냈으며, 고상 반응의 경우와 마찬가지로 Y/Nb 비율이 화학 양론상의 1:1인 경우보다 결함구조를 인위적으로 조절한 51/49나 54/46에서 최대의 발광강도를 보였다. 한편, 고상 반응에서는 125$0^{\circ}C$에서 4시간 열처리하는 것이 최대의 발광효과를 나타냈으나, B2O3융제를 첨가하고 110$0^{\circ}C$에서 열처리한 시료가 결정성이 좋고 입자의 크기 및 형태가 균일하여 PL뿐만 아니라 CL에서도 우수한 발광특성을 보였다. B2O3융제를 첨가하는 방법으로 열처리 온도를 낮추고 입자크기와 형태를 조절하여 형광체의 휘도를 개선할 수 있었다.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.75-79
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• 2010

The precursor powders with thin wall structure were prepared by spray pyrolysis from the spray solution with ethylenediaminetetraacetic acid, citric acid and $NH_4Cl$ flux. The $BaMgAl_{10}O_{17}:Eu$ phosphor powders formed from the spray solution without organic additives and flux material had sizes of $1{\sim}5{\mu}m$ and hollow structure with high thickness at post-treatment temperature of $1,200^{\circ}C$. However, $BaMgAl_{10}O_{17}:Eu$ phosphor powders formed from the spray solution with ethylenediaminetetraacetic acid, citric acid and $NH_4Cl$ flux had fine size and plate-like shape. The mean crystallite sizes of the phosphor powders with fine sizes were 23, 35, and 33 nm when the content of $NH_4Cl$ flux were 0, 6, 35 wt% of phosphor. The photoluminescence intensity of the phosphor powders formed from the spray solution with the optimum amount of $NH_4Cl$ flux as 35 wt% was 215% of that of the phosphor powders formed from the spray solution without flux material.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.616-620
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• 2005

The morphology and photoluminescence characteristics of green light emitting hexaaluminate phosphor particles prepared by high temperature spray pyrolysis from spray solution with and without ammonium dihydrogen phosphate flux were investigated. The particles prepared from spray solution without flux material had hollow morphology at preparation temperatures between $900^{\circ}C$ and $1,650^{\circ}C$. Ammonium dihydrogen phosphate flux added into spray solution enabled the formation of particles with spherical shape and filled morphology at preparation temperatures between $900^{\circ}C$ and $1,650^{\circ}C$. The hexaaluminate phosphor particles with magnetoplumbite structure were directly prepared by spray pyrolysis from spray solution with ammonium dihydrogen phosphate flux above $1,600^{\circ}C$. Ammonium dihydrogen phosphate flux was effective in improving the photoluminescence intensity of the phosphor particles at low preparation temperatures. The phosphor particles prepared from spray solution with and without flux material by spray pyrolysis under reducing atmosphere at $1,650^{\circ}C$ had comparable photoluminescence intensities with that of the phosphor particles optimized by post-treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.27-28
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• 1988

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.532-538
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• 1998

Emerald ($3BeO{\cdot}Al_2O_3{\cdot}6SiO_2:Cr^{3+}$) single crystal was grown by temperature gradient reflux method with using Korean natural beryl. The flux of lithium-molibudenium-vanadium oxide system was made by means of mixing the 2 sort of flux which were differently melted $Mo_3-Li_2O$ and $V_2O_5-Li_2O$ each other. The optimum composition of flux was 3 mole ratio of molibudenium. vanadium oxides to lithium oxide ($(MoO_3+V_2O_5)/Li_2O$), flux additives were substituted more less then 0.2 mole% of $K_2O$ or $Na_2O$ to the $Li_2O$ amount. The melting concentration of mixing beryl material was 3~10% content to the flux, that of $Cr_2O_3$ color dopant was 1% to the beryl amount. In the crystal growing apparatus with temperature gradient in the 3 zone furnace which was separated into the block of melt, growth and return, the solution have got to circulate continuously between $1100^{\circ}C$ and $1000^{\circ}C$ in steady state. When thermal fluctuation was treated to during 2 hrs once on a day at 950~$1000^{\circ}C$ in growth zone, the supersaturation solution was maintained, controled and emerald single crystal can be grown large crystal which was prevented from the nucleation of microcrystallite. The preferencial growth direction of hexagonal columnar emerald single crystal was the c(0001) plane of botton side and vertical to the m(1010) plane of post side.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.80-84
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• 2005

Nano-sized $Y_2O_3:Eu$ phosphor particles were prepared by ultrasonic spray pyrolysis. The effect of polymeric precursor and lithium carbonate flux on the morphology and luminescence characteristics of nano-sized $Y_2O_3:Eu$ phosphor particles was investigated. When using the spray solution containing both the polymeric precursor and the flux, the $Y_2O_3:Eu$ particles with spherical shape and micron size were turned into nano-sized $Y_2O_3:Eu$ phosphor particles during the post-treatment at high temperature. The mean size of $Y_2O_3:Eu$ phosphor particles was affected by the contents of polymeric precursors and lithium carbonate flux, and preparation temperature. The as-prepared particles by spray pyrolysis at high temperature from solution containing high contents of polymeric precursors had good photoluminescence intensity under vacuum ultraviolet after post-treatment above $1,000^{\circ}C$. The prepared nano-sized $Y_2O_3:Eu$ phosphor particles had comparable photoluminescence intensity under vacuum ultraviolet light with that of the commercial $Y_2O_3:Eu$ phosphor particles prepared by solid state reaction method.

• Journal of Conservation Science
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• v.33 no.2
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• pp.131-147
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• 2017

The purpose of this study is to analyze the characteristics of Punchong and Whiteware pottery excavated from the kiln site in Dongkok-Town, Gimge. Scientific analysis is carried out to evaluate the physical and chemical properties of the body and glaze. The physical properties indicate the gradual development of the production technology with respect to the kiln operating conditions and period. In chemical properties, the ceramic body is found to be made of raw materials from the same source, but the mixing method depends on the type of Punchong and Whiteware pottery, the production kiln, and period. Whiteware pottery is manufactured with less over 1.3% of the colorant content and more about 1.2% of the $K_2O$ flux content than Punchong pottery. This compositions allow easier vitrification at the same temperature. These characteristics which is low colorant content and high flux content become more prominent as lately. The ceramic glaze is likely to have changed the type of raw materials used after 16~17C, as the contents of MgO, $TiO_2$, MnO, $P_2O_5$ are less three to ten times than 15C.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.48-53
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• 2009

The effect of bloating and fluxing agent on the microstructure and physical properties were studied in manufacturing the artificial lightweight aggregates of bulk density below] using clay and stone sludge. In case of the aggregates added only with bloating agent, the bulk density and water absorption were $0.5{\sim}1.0$ and $41{\sim}110%$ respectively but the microstucture was not uniform with a rough appearance. For the aggregates added with a fluxing agent and one bloating agent, a part of shell was lost due to explosion of specimen caused by over-bloating during a sintering. The mixed addition of bloating agents with vacuum oil, carbon and ${Fe_2}{O_3}$ made the microstructure homogeneous by generating an uniform black core and shell structure. The aggregates added with mixed agents and sintered at $1200^{\circ}C$ showed the bulk density 67 % lower and water absorption 48 times higher than those of the specimen with no additives. ]n this study, the artificial lightweight aggregates showing the bulk density of $0.5{\sim}1.0$ and water absorption of $50{\sim}125%$ could be fabricated to apply to various fields.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.407-411
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• 2005

YAG:Tb($Y_3Al_5O_{12}:Tb$) phosphor particles were prepared by spray pyrolysis from spray solution containing various types of flux materials. The effects of type of flux, organic material and post-treatment temperature on the characteristics of morphology, crystallinity and photoluminescence of YAG:Tb phosphor particles were investigated. Citric acid and ethylene glycol used as organic additive improved the photoluminescence intensity of the YAG:Tb phosphor particles without destruction of the morphology after post-treatment at high temperature. However, the spherical shape of the precursor particles obtained by spray pyrolysis from spray solution containing high amount of flux material disappeared after post-treatment at $1300^{\circ}C$. YAG:Tb phosphor particles prepared from spray solution containing lithium carbonate flux had fine size and regular morphology after post-treatment. Lithium carbonate used as flux material was also efficient in improvement of the photoluminescence intensity of the YAG:Tb phosphor particles. The optimum photoluminescence intensity of the YAG:Tb phosphor particles prepared from spray solution containing lithium carbonate flux was 189％ of that of the phosphor particles prepared from spray solution without flux material.