• Journal of the Korean institute of surface engineering
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• v.34 no.3
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• pp.240-246
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• 2001

The possibility of using a glass block with the composition of sodium borosilicate as starting materials for GRIN glass was examined from the view points of the phase separation of the matrix glass, the effects of leaching and the heating conditions for a porous structure, and the change in the refractive index. Glass specimens with similar compositions were prepared in the form of porous glass using a phase-separation technique. An examination of the heating and leaching conditions and the microstructure dependence of these conditions was made.; Specimens with porous structure were obtained when the heat treatment and leaching conditions were fixed at $540^{\circ}C$ for 30hrs and in a 0.3N$ H_2$$SO_4$ solution at $100^{\circ}C$, respectively. The resultant specimens had some important features on the GRIN glass.; the depth of the gradient and the change in refractive index (Δn) were 4mm and 0.015~0.02, respectively.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.385-393
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• 1995

Akali-resistant porous glass was prepared by phase separation in Na2O-B2O3-SiO2 system containing ZrO2 and MgO. ZrO2 was added for alkali-resistance and MgO for anti-cracking during leaching. Optimal content of ZrO2 for alkali-resistance was 7wt% and devitrification by heat treatment resulted from further addition. Pore size and pore volume were decreased and specific surface area was increased with ZrO2 addition due to depression in phase separation. Addition of 3mol% MgO to mother glass containing 7wt% ZrO2 was effective for anti-crack during leaching. In this case, with phase separation at 55$0^{\circ}C$ and 5$25^{\circ}C$ for 20 hrs. crack-free porous glasses could be prepared. The relation between pore size r and heat treatment time t at 55$0^{\circ}C$ was D=25.58＋18.16t. According to measurement of gas permeability, the mechanism of gas permeation was Knudsen flow. N2 and He permeability of porous glass which was prepared by heat treatment at 55$0^{\circ}C$ for 20 hrs. were 0.843$\times$10-7mol/$m^2$.s.Pa and 2.161$\times$10-7mol/$m^2$.s.Pa respectively.

• Journal of the Korean Ceramic Society
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• v.43 no.5 s.288
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• pp.277-283
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• 2006

A porous material with a surface layer was fabricated from glass abrasive sludge and expanding agents. The glass abrasive sludges were mixed with expanding agents and compacted into precursors. These precursors were sintered in the range of $700-900^{\circ}C$ for 20 min. The sintered porous materials had a surface layer with smaller pores and inner parts with larger pores. The surface layer and closed pores controlled water absorption. As the expanding agent fraction and the sintering temperature increased, the porosity and pore size increased. The porous materials with $Fe_2O_3$ and graphite as the expanding agents had a low absorption ratio of about 3% or lower while the porous material with $CaCO_3$ as the expanding agent had a higher absorption ratio and more open pores.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.169-174
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• 1993

The porous silica glass prepared by the sol-gel method from the mixed solution of Si(OCH3)4, H2O, HCl and CH3OH with HCONH2 as a DCCA (Drying Control Chemical Additives). For investigation the characteristics of gels and glasses, we examined gels and glasses using TG-DTA, XRD, IR, SEM and porosimeter. The more content of formamide in the mixed solution increased, the more pore size and porosity of gel increased. In the excess formamide added gel, the properties of pore of gel were not so changed. The porous silica glass was prepared from the dry gel after heat treatment at 75$0^{\circ}C$. Porosity and mean pore size of the porous silica glass was 17~25% and 40~60$\AA$ relatively.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1337-1345
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• 1994

Glasses in the system of 45CaO-25TiO2-30P2O5 containing 1 mole% of M2O(M=Li, Na, K) were melted and crystallized. And their crystal phases were Ca3(PO4)2, CaTi4(PO4)6, and TiO2. Porous glass-ceramics with skeleton of two crystal phase CaTi4(PO4)6 and TiO2 were prepared by selective leaching of Ca3(PO4)2 with 0.1 N-HCl. Glass transition temperature(Tg) and crystallization temperature(Tc) were decreased by addition of 1 mole% alkali metal oxide. Pore size of porous glass-ceramics was increased with increasing heat treatment temperature and its dependence on heat treatment temperature was decreased with addition of Na2O and K2O. It was found that porous glass-ceramics of parent glass and containing 1mole% M2O(M=Li, Na, K) composition had maximum specific surface area, porosity and maximum of crystallzed phase by heat treatment at 80$0^{\circ}C$, 76$0^{\circ}C$, 78$0^{\circ}C$, 80$0^{\circ}C$ respectively.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.609-614
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• 2009

The low-temperature preparation of porous ceramics was carried out using mixtures of alumina-zinc borosilicate (ZBS) glass. The compositions of alumina-ZBS glass mixture with PMMA pore-former were unfortunately densified. Because PMMA was evaporated below the softening point of ZBS glass ($588{^{\circ}C}$), the densification through the pore-filling caused by the capillary force might occur. Howerver, those with carbon possessed pores where carbon was evaporated above the softening point. The porous ceramic having 35% porosity was successively fabricated by the low-temperature sintering process below $900{^{\circ}C}$ using 45 vol% of alumina, 45 vol% ZBS of glass, and 10 vol% of carbon as starting materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.476-481
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• 2009

The waste sheet glass cullet and hydroxyapatite is applied to make the fine porous glass. It's mechanical strength is examined, and the structure of porous glass is observed. The pore size and shapes were not homogeneous and bigger pore size when HAp was over 7%. In the sintering temperature range of $830{\sim}840^{\circ}C$, and $3{\sim}5%$ of HAp were showed about $10{\mu}m$ pore size and homogenous morphology. The compressive strength and bending strength were appeared about $18kg/cm^2$, $8kg/cm^2$ respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.606-607
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• 2006

A porous material with a surface layer was fabricated using glass abrasive sludge and expanding agents. The glass abrasive sludges were mixed with expanding agents and compacted into pellets. These pellets were sintered in the range of $700-900^{\circ}C$ for 20min. The sintered porous materials had a surface layer with smaller pores and inner parts with larger pores. The surface layer and pores controlled the absorption ratio and physical properties.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.625-628
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• 2004

Porous anodic alumina(PAA) which has arrays of nano size holes, was incorporated into organic light emitting devices. Porous anodic alumina on glass scattered the light generated from emitting layer and was decreased the waveguiding modes within the glass. An increase in the device coupling-out factor for the scattering structure is demonstrated.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.1
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• pp.112-120
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• 1996

In this study, the porous glass media was utilized as biomass carrier, and the optimum characteristics of this new media in fixed bed biofilm process were investigated. The characteristics of media considered here are a void volume fraction, a specific surface area, and surface characteristics of media. The effect of surface roughness and material could be clearly demonstrated by the fact that the porous glass media showed a good potential for biofilm development. This might results from the fact that biofilm is initially formed in the surface cavities of the media is protect from the shear effect. Therefore, the microcolonies are not readily detached by the fluid shear. In the steady state, biofilm formation along the packing bed depth was different from media to media. The specific area was also an important factor for the attachment of microorganism on the media surface. The specific area was also an important factor for the attachment of microorganism on the media surface. In the case of porous glass media, about $100m^2/m^3$ was enough to obtain a good organic removal efficiency The organic removal efficiency could be improved by increasing the void volume fraction in the reactor, at least 80% was required to obtain a high removal efficiency and prevent clogging. From the analysis of kinetics study, the yield coefficient, Y, was 0.42 mgMLSS/mgSBOD, endogenous respiration coefficient, ke, was $0.12day^{-1}$ and substrate removel coefficient of Mckinney. km, was $16.8hr^{-1}$ for the porous glass media G-2