• Journal of Conservation Science
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• v.23
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• pp.1-10
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• 2008

Consolidants based on tetraethoxysilane (TEOS) such as alkoxysilanes have been widely used for the consolidation of decaying stone heritages. Low-viscosity alkoxysilanes penetrate inside the decaying stone and polymerize within the porous structure of the decaying stone, significantly increasing the cohesion of the material. However, TEOS-based consolidants suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developed capillary force, which is typical for TEOS-based consolidants. We prepared new consolidants TEOS-based consolidants containing flexible (3-glycidoxypropyl)trimethoxysilane (GPTMS) and silica nanoparticles (or polyhedral oligomeric silsesquioxanes (POSS)) in order to reduce capillary force development during gel drying. Since the consolidants should have a good interaction with the component of the stone in order to connect the isolate grains of decaying stone, the adhesion interaction of the developed consolidants on the surface of the granite was macroscopically investigated by the ISO 2409 cross cutting test. The adhesion interaction decreased with the addition of silica nanoparticle and POSS while it increased with the addition of GPTMS in TEOS solution.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.481-484
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• 2007

마이크로 이미징은 물 분자가 하이드레이트 구조로 전환되는 것을 미시적으로 관찰할 수 있다. 본 고에서는 메탄과 $CO_2$ 하이드레이트 생성 실험을 실리카 젤과 bulk water를 이용해 실시하면서 이를 마이크로 이미징으로 관찰한 결과를 제시하고자 한다. Bulk water에서 하이드레이트 shell에 의해 하이드레이트 생성 속도가 제한을 받는 반면, 실리카 젤에서는 미세 pore에서의 생성 특성이 매우 빠르게 진행되는 것으로 관찰되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.73-78
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• 2003

The influence of calcination temperature on the pore structure of freeze dried silica gel derived from tetraethyl orthosilicate (TEOS) was investigated using $N_2$adsorption and mercury intrusion techniques. Freeze dried material contained not only 4-6 nm sized mesopores and 6-10 $\mu\textrm{m}$ sized macropores, but minor micropores. The change of pore structure due to the increase of calcination temperature was dependant upon the degree of densification.

• KSBB Journal
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• v.17 no.4
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• pp.365-369
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• 2002

An iron-storage protein, ferritin is a spherical shell consisting of 24 H-and L-chain subunits. Soluble form of fused($F_{H}+F_{L}$ chain) ferritin was separated from disrupted recombinant E. coii cells, followed by silica powder adsorption. Ferritin was recovered from silica-poweder by distilled water, which was applied to gel filtration chromatography(GFC). Collected ferritin fractions from the GFC were assayed via iron-uptake and its molecular weight determined using GF-HPLC. Fused ferritin showed a higher activity than the M- or L- chain ferritin by two times.

• Polymer(Korea)
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• v.31 no.2
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• pp.111-116
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• 2007

Polyurethane modified acrylate $(PUA)/SiO_2$ hybrid films were prepared by ultraviolet curing and their surface properties were investigated by hardness and adhesion test. The films were examined by the manipulation of mole-ratio of organic to inorganic components. Under the silica content controlled, highly desirable films were achieved and scratch resistance and hardness property of film were also enhanced, which indicates that the crosslinked silica particles are homogeneously dispersed within PUA film.

• Resources Recycling
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• v.17 no.6
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• pp.34-42
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• 2008

The properties of sodium silicate solution were surveyed by using the yellow silicomolybdic method, and the formation of silica sol from sodium silicate solution and the growth of silica sol were investigated in this study. The $SiO_2$ content of 2 wt% in sodium silicate solution was proper to oxidize sodium silicate with sulfuric acid. After the removal of sodium ions in sodium silicate solution, the pH of silicate solution had to be controlled above 9 for the stabilization of silicate solution. The condensation between silicic acid species and silica nuclei surfaces has been studied at $20{\sim}80^{\circ}C$ and pH 10 in silicate solutions with silica nuclei. The reaction falls into two kinetics regimes, limited at high silicic acid species concentration by polymerization, but at lower concentration by a process whereby deposited silicic acid species condenses further to silica. The overall condensation is first-order in silicic acid species concentration, proceeded toward to pseudo equilibrium concentration, $C_x$, rather than the solubility of amorphous silica. The heat of solution of amorphous silica was 3.34 kcal/mol and exhibits an Arrhenius temperature dependence with an apparent activation energy of 3.16 kcal/mol in the range of $20{\sim}80^{\circ}C$.

• Polymer(Korea)
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• v.28 no.5
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• pp.391-396
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• 2004

In order to overcome drawbacks in the conventional preparation of epoxy/silica nanocomposites, such as formation of micro voids and dimensional instability caused by evolution of volatile by-products during curing reaction, a novel preparation method using Si-N precursor has been proposed. When prepared through in-situ reaction of epoxy curing reaction with sol-gel reaction of Si-N precursor, methyltripiperidinylsilane (MTPS) which does not produce by-products during reaction, epoxy/silica nanocomposites of extremely even dispersion of inorganic phase could be successfully prepared, resulting in high enhancement of mechanical and thermal properties as well as outstanding transparency.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.151.1-151
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• 2002

• Journal of the Korean Ceramic Society
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• v.42 no.3 s.274
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• pp.205-210
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• 2005

Nanoscale silica powder was synthesized from $SiO_2$ precursor solution using Tetraethyl Orthosilicate (TEOS) by polyacrylamide gel method. This process was of simplicity and provided ultrafine powders at relatively low calcination temperatures because polymer network could inhibit aggregation of $SiO_2$ powder. The particle size of Si02 powder was affected by the concentration of ammonium persulphate and N, N'-methylene-bis-acrylamide(BIS) in the gel precursor. The particle size decreased with increasing ammonium persulphate and was mininum size of 10 nm at 0.01 M. Also, the size decreased with increasing BIS concentration and was 5 nm at its concentration of 0.05 M.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.261-263
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• 2007

본 연구는 광전자 촉매시스템을 이용해 $TiO_{2}$ 졸이 코팅된 구형 비드의 광분해 효율에 대해 고찰한 것이다. $TiO_{2}$ 졸이 코팅된 구형 비드인 알루미늄비드, 유리비드, 실리카비드 화이트젤 ($1{\cdot}2{\cdot}3$형) 다섯 가지 비드를 사용하였고 실험은 산화환원지시 약인 메틸렌블루 수용액이 광촉매의 산화환원반웅을 통해 색상 및 홉광도 변화를 통해 환원 청도를 고찰할 목적으로 실행되었다. 소재별 실험 결과, 실험에 사용한 소재 중 실리카비드 화이트첼($1{\cdot}2{\cdot}3$형)만이 반응성을 나타냈다. 이들 $1{\cdot}2{\cdot}3$형은 $TiO_{2}$의 함량을 달리한 비드들이며 1형이 가장 적은 함량을 가지며 3형이 가장 많은 함량을 가지고 있다. 실험 결과 3형이 반응성이 가장 좋은 것을 알 수 있으며, 이 실험에서는 코팅물의 함량과 고정물의 상태가 광촉매 반응에 영향을 주는 것을 알 수 있다.