• Korean Journal of Materials Research
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• v.24 no.12
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• pp.700-703
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• 2014

Calcium phosphate minerals are biologically important because of their application in the fields of orthopaedics and dentistry. Herein we have tried to synthesize calcium phosphate minerals from biowaste clam shells. A simple microwave method was used to synthesize a mixture of calcium phosphate minerals such as hydroxyapatite, tri-calcium phosphate, and monetite. The microwave induces vibration of the dipole ions in the reagent. The heating and rearrangement of ions and atoms occurs during the process. The phases obtained in the final powder were ascertained by X-ray diffraction; the morphology of each sample was checked using a scanning electron microscope. We were able to obtain a mixture of calcium phosphate minerals using the microwave method; the calcined powder showed a brick like morphology, which is different from the rod shape morphology of the hydroxyapatite obtained using the hydrothermal process.

• Journal of the Korean Applied Science and Technology
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• v.19 no.4
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• pp.251-257
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• 2002

Liquid-phase methanol synthesis via methyl formate using coal-derived syngas was carried out in a bench-scale(diameter 173 mm and dispersion height 1200 mm) slurry bubble column reactor(SBCR) Under the condition of $180^{\circ}$. 61 atm, 30 L/min, $H_{2}$/CO=2 and a slurry mixture of 2 kg of copper chromite and 0.5 kg of $KOCH_{3}$ suspended in 14 L of methanol, the per pass conversions of syngas is 6 %, maximum concentration of methyl formate 3.088 mol% and maximum synthesis, rate of methanol 0.8 gmole/kg ${\cdot}$ hr. It is a significant evidence that copper chromite powder as heterogeneous catalyst didn't active for the hydrogenolysis of methyl formate to methanol, resulting copper chromite powder was not efficiently suspended in a slurry mixture. To enhance the hydrogenolysis of methyl formate in liquid-phase methanol synthesis process, the designed SBCR have need to use the higher specific gravity solvent and/or decrease the catalyst particle size.

• Polymer(Korea)
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• v.25 no.6
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• pp.811-817
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• 2001

Crystallization behaviour of bisphenol A polycarbonate(PC) from amorphous phase was studied by varing solvent/nonsolvent ratios in liquid phase. Chloroform and isopropanol were used as a solvent and a nonsolvent, respectively. Samples were characterized by optical microphotography, scanning electron microscope (SEM), X-ray diffaction (XRD), and differential scanning calorimeter (DSC). DSC and XRD measurement were used to determine the crystallinity of PC. The solubility constant seems to critical to control the PC crystallinity in solvent/nonsolvent mixture. The difference in PC crystallinity is explained by the difference in solubility constant of the mixture depending on the solvent/nonsolvent ratio. PC solution of 75/25 wt% (solvent/nonsolvent) ratio produced PC powder showing maximum crystallinity. At this condition solubility constant (9.85) of the mixed solvent was close to PC (9.9).

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.572-577
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• 2010

Reaction-bonded $Si_3N_4$ has cost-reduction merit because inexpensive silicon powder was used as a start material. But its density was not so high enough to be used for structural materials. So the sintered reaction-bonded $Si_3N_4$techniques were developed to solve the low density problem. In this study the sintered reaction-bonded $Si_3N_4$ manufacturing method by using polymer precursor which recently attained significant interest owing to the good shaping and processing ability was proposed. The formations, properties of reaction-bonded $Si_3N_4$ from silicon and polysilazane mixture were investigated. High density reaction-bonded $Si_3N_4$ was manufactured from silicon and silicon-containing preceramic polymers and post-sintering technique. The mixtures of silicon powder and polysilazane were prepared and reaction sintered in $N_2$ atmosphere at $1350^{\circ}C$ and post-sintered at 1600~$1950^{\circ}C$. Density and phase were analyzed and correlated to the resulting material properties.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.170-174
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• 2009

$BaTiO_3$ powder was synthesized by the solid-state reaction of fine $BaTiO_3$ and $TiO_2$ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of $BaTiO_3$ and $TiO_2$ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of $BaTiO_3$ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, $BaTiO_3$ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. $BaTiO_3$ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.

• Journal of Pharmaceutical Investigation
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• v.16 no.2
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• pp.55-67
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• 1986

Inclusion complexation of tiaprofenic acid (TPA) with cyclodextrins $({\alpha}-,\;{\beta}-,\;{\gamma}-CyDs)$ in aqueous solution and in solid phase was investigated by solubility method, measurement of partition coefficient, ultra-violet, circular dichroism, infrared spectroscopies, powder X-ray diffractometry and differential scanning calorimetry. Investigations were made to prepare inclusion complexes of TPA with ${\beta}-CyD$ in solid powdered form by coprecipitation, freeze-drying, spray-drying and co-pulverization methods. The coprecipitation, freeze-drying and spray-drying methods were successful in obtaining inclusion complexes. The results showed that the latter two methods might be originally superior to the former in obtaining powdered inclusion completes. Especially, it was shown by powder X-ray diffractometry that spray-dried ${\beta}-CyD$ alone, TPA-spray-dried ${\beta}-CyD$ physical mixture, and spray-dried $TPA-{\beta}-CyD$ complex were amorphous. The dissolution behaviours of $TPA-{\beta}-CyD$ systems prepared by above four methods were compared with those of TPA alone and $TPA-{\beta}-CyD$ physical mixture, and the rates of dissolution of TPA in pH 1.2 buffer were greatly enhanced by inclusion complexation and copulverization.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.95-99
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• 2013

Lead zirconate titanate (PZT) thick films with a thickness of $10-20{\mu}m$ were fabricated on silicone substrates using an aerosol deposition method. The starting powder, which had diameters of $1-2{\mu}m$, was observed using SEM. The average diameter ($d_{50}$) was $1.1{\mu}m$. An XRD analysis showed a typical perovskite structure, a mixture of the tetragonal phase and rhombohedral phase. The as-deposited film with nano-sized grains had a fairly dense microstructure without any cracks. The deposited film showed a mixture of an amorphous phase and a very fine crystalline phase by diffraction pattern analysis using TEM. The as-deposited films on silicon were annealed at a temperature of $700^{\circ}C$. A 20-${\mu}m$ thick PZT film was torn out as a result of the high compressive stress between the PZT film and substrate.

• Journal of Pharmaceutical Investigation
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• v.38 no.1
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• pp.1-8
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• 2008

Planetary ball mill was used to decrease and control the particle size of excipients. The effects of the weight of sample and the revolution number of mill, and grinding time on the particle size of the ground sample were analyzed by response surface methodology. The optimum conditions for the milling of microcrystalline cellulose were 38.82 g of the weight of sample and 259 rpm of the revolution number of mill, and 45 minutes of grinding time. The predicted value of the particle size at the these conditions was $19.02{\mu}m$, of which the experimental value at the similar conditions was $18.68{\mu}m$. The tensile strength of tablets of single-component powders, such as microcrystalline cellulose, hydroxypropylmethyl cellulose and starch, binary mixtures and ground binary mixtures of these powder were measured at various relative densities. It was found that the logarithm of the tensile strength of the tablets was proportional to the relative density. A simple model, based upon Ryshkewitch-Duckworth equation that was originally proposed for porous materials, has been developed in order to predict the relationship between the tensile strength and relative density of ground binary tablets based on the properties of the constituent single-component powders. The validity of the model has been verified with experimental results for ground binary mixtures. It has demonstrated that this model can well predict the tensile strength of ground binary mixtures based upon the properties of single-component powders, such as true density, and the compositions. When the tensile strength of the mixture of microcrystalline cellulose hydroxypropylmethyl cellulose (90:10) and the ground mixture of them were compared, the tensile strength of the ground mixture decreased widely from 45.3 to 5.6% compared to the mixture in case the relative density of tablets was in the range of $0.7{\sim}0.9$. When the tensile strength of the mixture of microcrystalline cellulose starch (80:20) and the ground mixture of them were compared, the tensile strength of the ground mixture decreased widely from 31.0 to 11.6% compared to the mixture in case the relative density of tablets was in the range of $0.7{\sim}0.9$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.4
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• pp.505-511
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• 2008

This study was carried out to investigate the antioxidative effect of Kochujang seasoning sauce with the addition of fruit and vegetable extract (FVE) for pork Bulgogi, as well as to establish the optimum mixture ratio of ingredients using mixture experimental design (MED). During 5 months of storage at $-25^{\circ}C$, the thiobarbituric acid (TBA) values of the seasoned pork containing soy sauce (control), Kochujang added group (KG) and Kochujang and FVE added group (KFVEG) were remarkably lower than that of unseasoned pork. Among the seasoned porks, the antioxidative effect of KG was much higher than the control. Moreover, TBA values of KFVEG were significantly lower than those of KG. Therefore, the lipid oxidation stability of seasoned pork Bulgogi was improved by the addition of Kochujang, red pepper powder and FVE into the seasoning sauce. When Kochujang was used in seasoning sauce, the preference scores of pork Bulgogi increased with the increasing amount of red pepper powder and FVE. The optimum mixture ratios of seasoning sauce for pork Bulgogi established by the MED were Kochujang 0.04, red pepper powder 0.20, FVE 0.39 and water 0.37.

• Food Science and Preservation
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• v.19 no.2
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• pp.223-228
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• 2012

The effects of soybean powder and $chungkukjang$ powder on the quality characteristics of bread were investigated. The nutritional elements of the soybean powder, $chungkukjang$ powder and wheat flour differed remarkably. The average crude protein, ash, crude lipid, and fiber of soybean powder and $chungkukjang$ powder were approximately 3, 15, 8 and 5 times higher than those of the wheat flour, respectively. The properties of the dough to which soybean powder and $chungkukjang$ powder were added, i.e., its water absorption (%), development time (min) and stability (min) were measured with a farinograph. The water absorption, and development time of the farinogram increased, but its stability decreased when soybean powder and $chungkukjang$ powder were added to white wheat flour. As long as the mixture rate of soybean powder and $chungkukjang$ powder increased, the loaf volume of the bread declined, but the weight significantly increased. The L value decreased, but the a and b values increased in bread crumb that was made from soybean powder and $chungkukjang$ powder. The white wheat flour to which 10% soybean powder and 5% $chungkukjang$ powder were added had the highest scores in flavor, color, texture, taste, and overall acceptability in the sensory evaluation.