• Food Engineering Progress
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• v.13 no.1
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• pp.44-49
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• 2009

Angelicae gigantis Radix (dried root of Angelica gigas) including major bioactives such as decursin and decursinol angelate provides rich flavors and several healthy benefits. Recent studies have shown that ultrafine powders of herbal medicines provide better physical properties and biological activities. Thus, ultrafine Angelica powder was added into the oligosaccharide syrup to provide flavors and healthy benefits in this study. Angelicae gigantis Radix was pulverized into d(0.1) = 3.220, d(0.5) = 7.822, and d(0.9) = 7.817 $\mu$m respectively using an air-flow mill. The ultrafine Angelica powder was added into the oligosaccharide syrup process with different ratios of water to oligosaccharide syrup at 1:5, 1:8, 1:11, and 1:14. The physicochemical properties such as viscosity and bulk density were measured. The Stokes' law was applied to predict the sedimentation velocity of the added Angelica powder in the syrup. The Angelica syrup prepared in this experiment showed good stability since the Angelica particles precipitated down slowly. The ratio of water to oligosaccharide syrup at 1:11 showed the optimal preparation in terms of the stability and the viscosity. The ultrafine-sized herbal powders such as Angelicae gigantis Radix have potentials for various food and pharmaceutical applications.

• Journal of the Korean Ceramic Society
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• v.28 no.3
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• pp.205-214
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• 1991

Calcium carbonate fine powders were synthesized by blowing CO2 gas in CaO or Ca(OH)2 suspension, and the shapes of powders obtained were examined for each synthetic condition. When water was used as a solvent, ultrafine calcite powders with the average size of∼0.03$\mu\textrm{m}$ were obtained. When synthesized using methanol as a solvent, amorphous phase and spherical vaterite phase were obtained by suction filtering and non-filtering, respectively. Reaction did not occured in ethanol medium, but spherical vaterite phase was obtained by adding ethylene glycol in ethanol.

• Proceedings of the Korean Ceranic Society Conference
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• 1986.12a
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• pp.87-113
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• 1986

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.325-332
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• 1998

Crystalline TiO2 ultrafine powders were prepared simply by heating and stirring aqueous TiOCl2 solution with {{{{ {Ti }^{4+ } }} concentration of 0.5 M from room temperature to 10$0^{\circ}C$ under 1 atmoshpere. The crystallinity and the particle shape of TiO2 ultrafine powders obtained by simple precipitation method were analyzed us-ing XRD(X-ray diffractometer). SEM(scanning electron microscopy) and TEM(transmission electron mi-croscopy) TiO2 crystalline precipitate with rutile phases is fully formed at the temperatures of up to $65^{\circ}C$ and then TiO2 crystalline precipitate with anatase phase starts to be formed above temperatures $65^{\circ}C$ showing its full formation at 10$0^{\circ}C$ These behaviors of TiO2 crystalline precipitate directly from an aqueous TiOCl2 solution would be caused due to the existence of {{{{ OMICRON ^2+ }} ions from distilled water which oxydize TiOCl2 to TiO2 not hydrolyzing it to Ti(OH)4 Here thermodynamically stable TiO2 rutile phase generally formed at higher temperature is practically precipitated at lower temperatures in this study This may be due to the precipitation by very slow reaction enough to make TiO2 particles allocated into stable rutile structure.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.269-277
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• 1995

Ultrafine TEX>$Al_2O_3$ powders were prepared from $AlCl_3$ and $Al_2(SO_4)_3$3 by using inductively coupled plasma (lCP) of ultrahigh temperature (above 5000 K) in heat source. The prepared $Al_2O_3$ powders had ${\alpha} - group ({\alpha}, {wdelta} ;and; {\theta})$ phase, a narrow size distribution and around 20 nm in meansize. It could be suggested that gas - solid reaction growth and interparticle sintering occured at the center of ICP tail flame (X = 500 mm) through the results of deposited aggregates - flock, whisker and platy on MgO polycrystal plate. And the formation mechanism of $Al_2O_3$ powders In spray - ICP reactor were described from upper results.

• Journal of Industrial Technology
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• v.17
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• pp.241-247
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• 1997

A numerical model has been proposed for a diffusion flame reactor to manufacture ultrafine $TiO_2$ powders. The model equations such as mass balance equation, the 0th, 1st, and 2nd moment equations of aerosols were considered. The phenomena such as $TiCl_4$ reaction rate, $TiO_2$ nucleation rate and the coagulation of $TiO_2$ powders were included in the aerosol dynamic equation. It is found that the $TiO_2$ particle concentration becomes higher, as the inlet $TiCl_4$ concentration and the total gas flow rate increase, and also as the flame temperature decreases. The $TiO_2$ particle size increases, as the flame temperature and the inlet $TiCl_4$ concentration increase and the total gas flow rate decreases.

• Journal of Powder Materials
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• v.18 no.4
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• pp.332-339
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• 2011

Cemented tungsten carbide has been used in cutting tools and die materials, and is an important industrial material. When the particle size is reduced to ultrafine, the hardness and other mechanical properties are improved remarkably. Ultrafine cemented carbide with high toughness and hardness is now widely used. The objective of this study is synthesis of nanostructured WC-Co powders by liquid phase method of tungstate. The precursor powders were obtained by freezen-drying of aqueous solution of soluble salts, such as ammonium metatungstate, cobalt nitrate. the final compositions were WC-10Co. In the case of liquid phase method, it can be observed synthesis of WC-10Co. The properties of powder produced at various temperature, were estimated from the SEM, BET and C/S analyser.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.120-120
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• 1999

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.10a
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• pp.14-15
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• 1997

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.25-28
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• 1995