• Korean Journal of Materials Research
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• v.13 no.3
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• pp.144-149
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• 2003

This study shows an experimental investigation of a reversible nano colloidal damper, which is statically loaded. The porous matrix is composed from silica gel (labyrinth or central-cavity architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis are described. Influence of the pore and particle diameters, particle architecture and length of the grafted molecule upon the reversible colloidal damper hysteresis is investigated, for distinctive types and mixtures of porous matrices. Variation of the reversible colloidal damper dissipated energy and efficiency with temperature, pressure, is illustrated. As a result, he proposed nano damper is effective one, which can be replaced the conventional damper.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.45-50
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• 2014

A fully packed capillary electrochromatographic (CEC) microchip with an on-column micro-solid phase extraction (SPE) bed for the preconcentration and separation of organic analytes was prepared. A linear microchannel with monodisperse colloidal silica packing was formed on a cyclic olefinic copolymer microchip with two reservoirs on both ends. Silver-cemented silica packing frit structure was formed at the entrance of the microchannel by electroless plating treatment as a base layer. A gold coating was formed on it by reducing $Au^{3+}$ to gold with hydroxylamine. Finally micro-SPE bed was formed by self-assembly adsorption of 1-dodecanethiol on it. Micro-SPE beds were about 100-150 ${\mu}m$ long. Approximately $10^3$ fold sensitivity enhancements for Sulforhodamine B, and Fluorescein in nM concentration levels were possible with 80 s preconcentration. Basic extraction characteristics were studied.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.981-987
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• 2002

Monodispersed colloidal silica was prepared by Stober process. We have synthesized monodispersed colloidal silica of carious sizes (100 nm, 200 nm, 300 nm) by controlling volume ratios of TEOS(Tetraethylorthosilicate), $NH_4OH$, Ethanol and D. I. water. Shape and monodispersity of the synthesized colloidal particles were observed by Scanning Electron Microscopy(SEM) and laser light scattering particle analyzer. Self-assembled monolayer of monodispersed colloids was achieved by dipping Si substrate into a well-dispersed silica suspension. It was determined that uniformity and spatial extent of the self-assemble monolayer of monodispersed colloids are significantly influenced by the experimental parameters such as concentration, pH and surface tension of the colloidal suspension. We have observed a hexagonally well-ordered packing colloidal monolayer in a relatively large area (1.5 mm ${\times}$ 1.5 mm) as confirmed by SEM.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.3
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• pp.137-142
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• 2021

In this study, the development of the room temperature curable silica-based coating compositions for anticorrosive and antifouling performance in marine environments was carried out. The marine (plant) structures with many exposed parts are operated in harsh marine environments such as strong ultraviolet rays, extreme temperature differences and salt water corrosion. Organic paints that are easily degraded under these environments and easily eroded by physical stimuli such as waves can not play a role properly. Dense ceramic coatings on marine structures provide careful protections even in saltwater environments due to their high hardness and rust resistance. Therefore, in the case of ceramic coatings, their use and application range in marine structures can be greatly improved due to their functional advantages. In the present study, silica-based coating compositions based on colloidal silica with silane coupling agents, curing salts, and ceramic fillers were developed, and their applications as protective coatings for corrosion protection and fouling prevention in seawater were also studied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.230-231
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• 2006

We synthesized sol according to kinds(particle size/stabilized ion) of colloidal silica(CS), content ratio of alkoxysilane versus CS and reaction degree in sol solution and studied the surface property of coated gel materials. The contact angle of the thin films prepared from LHSA/N1030 CS/tetramethoxysilane(TMOS)/methyltrimethoxysilane(MTMS) sol-gel reaction system showed a little good relationship with content ratio of TMOS/MTMS silanes. The surface roughness of LHSA CS/TMOS/MTMS reaction system showed flatter than that of LHSA/N1030 CS. The thermal degradation of LHSA CS/TMOS/MTMS coating flim occurred at $550^{\circ}C$.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.822-826
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• 2005

Colloidal Silica (CS)/methyltrimethoxysilane (MTMS) and CS/MTMS/epoxysilane (ES) sol solutions were prepared using various synthesizing parameters such as reaction time and types of CS and silane. In order to understand their physical and chemical properties, sol-gel coating films on glass were fabricated. In the case of the CS/MTMS sol, the coating films had high contact angle and more enhanced flat surface than the CS/MTMS/ES sol. In the case of thermal stability, thermal degradation of the CS/MTMS and CS/MTMS/ES coating films did not occur up to $550^{\circ}C$ and $440^{\circ}C$, respectively. The coating films prepared from the CS/MTMS sol were thicker than those of the CS/MTMS/ES sol. In addition, the coating films prepared from single CS were thicker than those of mixed CS. Hardness of the coating films prepared from CS/MTMS increased by adding ES. In case of the mixed CS, the hardness decreased by adding ES.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.53-58
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• 2012

In order to improve the surface hardness of transparent plastic films, an organic-inorganic hybrid coating solution was sunthesized by the sol-gel method. Coating solutions that were prepared colloidal silica (CS), poly methyl methacrylate (PMMA), vinyltrimethoxysilane (VTMS), and [3-(methacryloyloxy)]propyltrimethoxy silane (MAPTMS) was varied with synthesizing parameters such as kinds of organic silane and weight ratio of CS to PMMA. Such coating solution was bar coated on the PET film, cured, and investigated on the chemical and physical properties of coating film. The organic-inorganic hybrid coating solutions have better properties at the pencil hardness and adhesion of coating film than those of an organic material such as PMMA.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.691-696
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• 2011

Organic-inorganic hybrid coating solutions were prepared by using a sol-gel method for transparent film. In this study, colloidal silica (CS) and alkoxy silane such as vinyltrimethoxysilane (VTMS), and [3-(methacryloyloxy)]propyltri methoxy silane (MAPTMS) were used in various conditions such as types of organic silane, weight ratios of CS to silane and reaction times. Coating solutions which were bar coated on the PET (polyethyleneterephthalate) film and cured were investigated on the chemical and physical properties. The pencil hardness and adhesion of coating films were increased with increasing the organic silane content in the coating solution compared to that of PMMA (polymethamethylcrylate) coating solution.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.2
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• pp.59-66
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• 2003

A novel application of nano-technology in the field of engineering, called colloidal damper, is investigated. This device is complementary to the hydraulic damper, having a cylinder-piston construction. Particularly for colloidal damper, the hydraulic oil is replacedby a colloidal suspension, which is consisted from a nano-porous matrix with controlled architecture and a lyophobic fluid. In this experimental work, the porous matrix is composed from silica gel, with labyrinth architecture, coated by organo-silicones substances in order to achieve a hydrophobic surface. Water is considered as associated lyophobic fluid. The colloidal damper test rig and the measuring technique of the hysteresis are described. the influence of the hydrophobicity level upon the colloidal damper hysteresis is investigated, for silica gels with similar pores distribution. A certain desired shape of the hysteresis can be achieved by employing mixture of silica gels with different level of hydrophobicity and/or architecture. With these results, it is believed that the proposed damper can be designed and be applied to the desired structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.231-234
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• 2003

CS와 실란의 반응시 생성된 실란올들이 동종간의 반응에 비하여 실리카 표면과의 반응이 진행되는 효과에 따라서, 그리고 실란들의 종류에 따라 경화밀도와 재료특성이 상당히 달라지게 된다. 본 논문에서는 CS/MTMS 졸반응에서 CS의 종류, CS/MTMS의 함량비, 졸의 반응시간 등을 인자로 하여 졸들을 합성하고 겔화된 도막의 물성들을 조사하였다. 그 결과 MTMS의 함량과 비례하여 친수성은 증가하고 표면조도는 나아지는 것을 알 수 있었고 반응시간에 비례하여 친수성은 감소하고 표면조도는 안 좋아지는 것을 알 수 있었다. 그리고 내열성은 MTMS의 함량이 적을수록 좋은 결과를 나타내었다.