• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.47-54
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• 2014

Nanotechnology has become one of the fastest developing technologies and recently applied to a variety of industries. Thus, increasing number of nano materials including various nanoparticles would be discharged into wastewater and consequently entering a biological wastewater treatment process. However, the impact of the nano particles on biological wastewater treatment has not been estimated intensively. In this research, we investigated the effect of silica nanoparticle on the oxygen uptake rates (OURs) of activated sludge used in a conventional wastewater treatment process. The inhibition (%) values were estimated from the results of OURs experiments for the silica nanoparticles with various sizes of 10-15, 45-50, and 70-100 nm and concentrations of 50, 250, and 500 ppm. As results, the inhibition value was increased as the size of silica nano particles decreased and the injected concentration increased. The maximum inhibition value was investigated as 37.4 % for the silica nanoparticles with the size of 45-50 nm and concentration of 50 ppm. Additionally, the effect of size and concentration on the inhibition should be considered cautiously in case that the aggregation of particles occurred seriously so that the size of individual particles was increased in aquatic solution.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.399-400
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• 2009

This study arranged the result corrosion inhibition using Nano-silica for efficient prevention to diffusion of chloride ion. For the results, significant difference was not found on slump and air content, and there were superior effect to preventing diffusion of chloride ion on hardened concrete. It seemed to be Nano-silica prevented diffusion of chloride ion.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.13-16
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• 2005

Nanoscale materials are of great interest due to their unique optical, electrical and magnetic properties. Due to the recent amazing achievements in nano technology, new materials were developed. But these nano technology is not apply to the construction part in spite of exellent properties of nano size material. The purpose of this study is to apply to nano technology into building materials. To develop the high performance concrete, nano cement particles is prepared by mechanical method. In the results of this study, the nano silica powder increase effect according to increase of the mixing amount, appeared that compressive strength increased but is limit in increment. For the production of high-strength concrete, nano silica powder was suitable the binder ratio from 20$\%$. And, the compressive strength of concrete are especially dependent on the curing temperature.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1427-1429
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• 2010

• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2281-2283
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• 2008

• The Plant Pathology Journal
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• v.22 no.3
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• pp.295-302
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• 2006

The present study addressed the efficacy of nanosized silica-silver for controlling plant pathogenic microorganisms. The nanosized silica-silver consisted of nano-silver combined with silica molecules and water soluble polymer, prepared by exposing a solution including silver salt, silicate and water soluble polymer to radioactive rays. The nanosized silica-silver showed antifungal activity against the tested phytopathogenic fungi at 3.0 ppm with varied degrees. In contrast, a number of beneficial bacteria or plant pathogenic bacteria were not significantly affected at 10 ppm level but completely inhibited by 100 ppm of nanosized silicasilver. Among the tested plant pathogenic fungi, the new product effectively controlled powdery mildews of pumpkin at 0.3 ppm in both field and greenhouse tests. The pathogens disappeared from the infected leaves 3 days after spray and the plants remained healthy thereafter. Our results suggested that the product developed in this study was effective in controlling various plant fungal diseases.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.45-50
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• 2008

The self assembled silver process and silver coating process after surface reforming for silica particle, were investigated to coat the silver to colloidal silica. The effects of silver amounts and reductant amounts on silver coating efficiencies were investigated. The silver coating process after surface reforming for silica particle using MPTS (3-Mercaptopropyl trimethoxysilane) and APTS (3-Aminopropyl trimethoxysilane), showed the higher coating efficiency and better antibacterial effect than the self assembled silver process.

• Journal of Powder Materials
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• v.9 no.5
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• pp.365-369
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• 2002

Silica hydrogel was synthesized by the reaction of liquid sodium silicate with sulfuric acid. The condensation polymerization of the synthesized hydrogel was carried out via an aging process under the acidic or alkaline conditions. Nano porous silica with the pore size below 3 nm and surface area of $715m^2/g$, was obtained by the above processes in acidic ranges(pH : 3~5). The pore size and surface area of the silica varied with pH, and in alkaline ranges(pH : 8~10), those were 21 nm and $300m^2/g$ respectively. The characteristics of the silica varied with the thermal treatment which caused the change of surface area, pore volume and pore diameter.

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.818-823
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• 2005

Sub-micron colloidal silica particles coated with nano-sized ceria were prepared by mixing of its silica and cerium salts hydrolysis, and modified by hydrothermal reaction. By using the slurries with and without hydrothermal modification containing above particles, oxide film coated on silicon wafer was polished. The modified slurries had higher polish rate due to increase of ceria fraction to silica through hydrothermal reaction. They revealed higher stability in wide range of pH $2\~10$ than ceria coated silica slurries without its modification.