• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.229-235
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• 2000

The spherical silica powder was synthesized by varying the kinds of solvent and mixing energy in emulsion method. The stirring speed varied from 500 to 1000 r.p.m. at 5$0^{\circ}C$ for 2h. Toluene in benzyl groups and a series of alkanes were used as dispersant. The average size of spherical silica particles decreased with increasing the stirring speed and the chain length o solvents used in this work. The average size was controlled in the range of 134~28$\mu\textrm{m}$ by selecting a proper solvent and stirring speed. The optimum processing parameters were described in details.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2979-2984
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• 2014

Silver nanoparticles have been synthesized by liquid-phase and alcohol reduction methods. Silver-doped silica-complex nanoparticles were prepared using a sol-gel process. The formation, structure, morphology, and particle size of the nanoparticles have been studied using several techniques. Silver nanoparticles of size of 30-40 nm were formed successfully by alcohol reduction. TEM images show that both the concentration and the molecular weight of polyvinyl pyrrolidone (PVP) considerably affect the size of the emerging silver nanoparticles. The number of silver-doped silica-complex particles increased by a mercapto-group treatment that showed a narrower size distribution than that of silica treated with amino groups. The silver/polyester and silver-doped silica/polyester masterbatch chips showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli.

• Journal of Magnetics
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• v.16 no.2
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• pp.186-191
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• 2011

[ $YBa_2C_3O_{7-x}$ ]films were fabricated on a $SrTiO_3$ (100) substrate using a trimethylaceate propionic acid (TMAP)-based MOD process by controlling the precursor solution viscosity, firing temperature, and by using various coatings. The viscosity of the precursor solution was controlled by the addition of Xylenes. The films were heat treated with different temperatures from 750 to $800^{\circ}C$. c-axis oriented films were obtained. After adding 9 ml of Xylene into the precursor solution, the $T_c$ of the YBCO film, which was coated 2 times and heat treated at $800^{\circ}C$, was 86 K and the measured $J_c$ was above 2.5 MA/$cm^2$ at 77 K in a zero-field.

• 한국유가공학회:학술대회논문집
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• 2004.11a
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• pp.17-29
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• 2004

Nanofood can be simply defined as natural polymer particles containing functional food materials in nanoscale that are synthesized by polymerization or emulisification process. They have very uniform diameters in the range of 1 to 100 nm and extensive surface areas due to the small particle size in spite of their non-porosity. Although the technique to produce nanofood has not Bong developing history, many works have been achieved in various fields. Nanofood has a lot of special advantages, such as functionality, diversity, applicability, etc. In case of the domestic food industries, however, the accumulation of related technique is insufficient against developed countries except used food materials. Also, it is difficult to acquire technical know-how from the developed countries that possess those technologies. We have been studied on preparing functional nanofood and developing new production processes since 1999. Last 5 years we have laid the foundation on the preparation of nanofood and now are focusing on developing new processes of nanofood and expending the field of its applications.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1097-1098
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• 2006

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. Silica coated $BaTiO_3$ powders were prepared by sol-gel method. The particle size of the $BaTiO_3$ powders were $\sim35$ nm and the thickness of the $SiO_2$ coating layer was $\sim5$ nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion. The Zeta potential of $SiO_2$ coated $BaTiO_3$ was getting close to that of pure silica with a more negative charge, compared with that of the uncoated $BaTiO_3$. The onset temperature of shrinkage curves shifted to higher temperatures with increasing $SiO_2$ contents

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.301-304
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• 2004

The objective of this study is to evaluate the physical properties of ultra fine-ground cement for grouting materials. This study investigates the compressive strength of cement paste, homogenized gel and solidified soil matrix with ultra fine-ground cement. Also It is estimated the injection properties of ultra fine-ground cement. From the test results, the compressive strength of ultra fine-ground cement is higher than that of portland cement. The injection properties are sufficient to apply silt-sand soil and minute-cracked rock bed. Also the properties of soil stability like water permeability coefficient are enough to be adapted various grouting specification.

• Journal of information and communication convergence engineering
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• v.1 no.2
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• pp.63-66
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• 2003

High $T_c$ superconducting lines will be applied as key materials in the areas of power transmission line; magnetic levitation of vehicle; magnetic separation; magnetic energy storage and marine propulsion. A combination method of electrophoresis deposition and zone-melting for preparation of YBaCuO tape is proposed. The submicron particle powder of YBaCuO made by sol-gel method is used in the electrophoresis process. A 40∼50 ${\mu}\textrm{m}$ thickness of YBaCuO film on Ag plate could be deposited in about three minutes. After deposition the film is rolled and heat treated in order to increase the density and the adhesion of the film to the Ag plate. Silver(Ag) and lead oxide(PbO) were added in the YBaCuO powder in order to reduce its melting point. The YBaCuO coating with controlled Ag and PbO contents was preliminarily zone-melted at about $945^{\circ}C$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.75-76
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• 2007

ZnS:Cu,Cl phosphor was coated by solid-gel reaction with $SiO_2$ outside layer. The effect of $Cu^{2+}$-doping concentration has been investigated on the luminescence characteristics of ZnS:Cu,Cl blue-green phosphors for inorganic electro luminescent device. Also, SiO2 coated layers' effect on luminescence characteristics. Evaluation of luminescence characteristics dependent on the synthesis conditions is important to get high-performance phosphors properties. EL and PL properties such as luminescence intensity and chromaticity of ZnS:Cu,Cl phosphors synthesized with different concentration of activator, $Cu^{2+}$, were analysed separately

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.112-113
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• 2007

ZnS:Cn,Cl phosphor was coated by solid-gel reaction with $SiO_2$ outside layer. The effect of $Cu^{2+}$ -doping concentration has been investigated on the luminescence characteristics of ZnS:Cn,Cl blue-green phosphors for inorganic electro luminescent device. Also, SiO2 coated layers' effect on luminescence characteristics. Evaluation of luminescence characteristics dependent on the synthesis conditions is important to get high-performance phosphors properties. EL and PL properties such as luminescence intensity and chromaticity of ZnS:Cn,Cl phosphors synthesized with different concentration of activator, $Cu^{2+}$, were analysed separately

• Korean Journal of Materials Research
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• v.15 no.7
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• pp.431-434
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• 2005

To investigate the dependences of the absorption spectrum and electronic structure properties on the ZnO nano-particle size, ZnO nanocrystals were synthesized by a sol-gel method. The absorption onset peak exhibits a systematic blue-shift with decreasing particle size due to the quantum confinement effect, as well as, with decreasing $Zn^{2+}$ concentration. The increase of particle size is mainly controlled by coarsening and aggregation step during the nucleation and growth of ZnO nano-particles. The onset absorption spectrum of ZnO colloids changes from 310 to 355 nm as $Zn^{2+}$ concentration increases from 0.01 to 0.1 mole. The average particle size as a function of aging- time can be determined from the absorption spectra. The freshly prepared nanocrystal size was about 2.8nm.