• Journal of Ginseng Research
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• v.14 no.2
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• pp.117-121
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• 1990

Browning intensity is a major factor to estimate the quality of red ginseng or red ginseng products. The Maillard type of browning reaction proceeds nonenzymatically during extraction and concentration of red ginseng. The present studies were carried out to investigate the effects of amino acids and sugars on the browning reaction during extraction and concentration of red ginseng. Red ginseng was pulverized to 115 mesh and then tenfold (v/w) of water was added to the powder to make the substrate of red ginseng. Solution (0.1 M) of fourteen amino acids and of folly silgars were added to the substrates of red ginseng powder and these were then extracted and concentrated to examine their browning intensities. Amino acids were more effective than sligars in acrelerating the browning reaction. Acceleration of the browning reaction in the concentrate was in the order of arginine> histidine>glycine>alanine>lysine phenyl alanine>aspartic acid>lelicine>threonine>gllitamic acid>tyrosine>valine>istleucine>methionine for amino acids, and was glucose>frlictose >silcrose, maltose for sugars.

• Journal of Powder Materials
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• v.4 no.3
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• pp.196-204
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• 1997

Joining of AIN ceramics to W and Cu by active-metal brazing method was tried with use of (Ag-Cu)-Ti alloy as insert-metal. Joints were produced under various conditions of temperature, holding time and Ti-content in (Ag-Cu) alloy Reaction and microstructural development in bonded interface were investigated through observation and analysis by SEM/EDS, EPMA and XRD. Joint strengths were measured by shear test. Bonded interface consists of two layers: an insert-metal layer of eutectic Ag- and Cu-rich phases and a reaction layer of TiN. Thickness of reaction layer increases with bonding temperature, holding time and Ti-content of insert-metal. It was confirmed that the growth of reaction layer is a diffusion-controlled process. Activation energy for this process was 260 KJ/mol which is lower than that for N diffusion in TiN. Maximum shear strength of 108 MPa and 72 MPa were obtained for AIN/W and AIN/Cu joints, respectively. Relationship between processing variables, joint strength and thickness of reaction layer was also explained.

• YAKHAK HOEJI
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• v.15 no.1
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• pp.24-31
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• 1971

Optimum reaction conditions for the preparation of extra-light magnesium carbonate from bittern by the reaction with sodium carbonate solution was found to be as follows: reaction temperature 33.deg. molar ratio(Mg$^{+2}/CO$^{2-}_{3}$)0.8, reaction time 14 minutes, drying temperature 99.deg. and bittern concentration 17%. While Korean pharmacopeia regulates the bulkiness above 12 mililiters per gm., our experimental result shows above 45 mililiters. Electron microscopic shapes were compared with products prepared under various reaction conditions, and it was found that there exists lighter the powder the more pillar crystalline, the heavier the powder the more amorphous and the intermediate was mixture of them.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.55-60
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• 2020

In the previous study, we reported the result to prepare lithium carbonate powder from various lithium-contained solution. Therefore, using the lithium hydroxide solution, it is conformed that the reaction could occur thermodynamically, and the recovery rate of lithium was 89.4 %. In this study, we carried out the experiment to prepare lithium carbonate powder through gas-liquid reactions with lithium hydroxide solution and CO₂ gas using ultrasound energy. In case ultrasonic energy is applied to the reaction of lithium carbonate, the recovery rate of lithium at room temperature was approximately 83.8 %, and the recovery rate of lithium was greatly increased to approximately 99.9 % at 60℃ reaction temperature. And when ultrasonic energy is not applied, the particle size of lithium carbonate powder was 7.7 ㎛ in D50. But the particle size of lithium carbonate powder was significantly reduced to 8.4 ㎛ in D50 under the influence of ultrasonic.

• Journal of Powder Materials
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• v.25 no.3
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• pp.232-239
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• 2018

In this paper, the recovery and nanoparticle synthesis of Ag from low temperature co-fired ceramic (LTCC) by-products are studied. The effect of reaction behavior on Ag leaching conditions from the LTCC by-products is confirmed. The optimum leaching conditions are determined to be: 5 M $HNO_3$, a reaction temperature of $75^{\circ}C$, and a pulp density of 50 g/L at 60 min. For the selective recovery of Ag, the [Cl]/[Ag] equivalence ratio experiment is performed using added HCl; most of the Ag (more than 99%) is recovered. The XRD and MP-AES results confirm that the powder is AgCl and that impurities are at less than 1%. Ag nanoparticles are synthesized using a chemical reduction process for recycling, $NaBH_4$ and PVP are used as reducing agents and dispersion stabilizers. UV-vis and FE-SEM results show that AgCl powder is precipitated and that Ag nanoparticles are synthesized. Ag nanoparticles of 100% Ag are obtained under the chemical reaction conditions.

• Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.403-408
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• 2014

Antarctic krill Euphausia superba is an excellent potential source of food protein. We used enzymatic hydrolysate of Antarctic krill and 10 other precursors to seek the optimum krill reaction flavor and apply to ramen sauce. Krill concentrate and powder were compared by sensory evaluation. The krill powder performed better preference, and was added to ramen sauce, which itself performed better than a commercial shrimp flavored sauce. In total, 47 and 39 volatile compounds were identified from krill concentrate and powder, respectively. Both products contained many aldehydes and sulfur-containing compounds. The whisky flavor of aldehydes lowered the shrimp flavor of the krill concentrate. Sulfur-containing compounds were found in krill powder, confirming the results from sensory evaluation.

• Resources Recycling
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• v.12 no.4
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• pp.51-57
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• 2003

Using the wastes of Ta powder fabrication process for capacitor, TaC powder was synthesized by SHS method. In previous to synthesis, the waste Ta was needed of milling and deoxidization treatments for active reaction and prevention of oxidation. In SHS reaction, it was found that the TaC single phase was obtained in composition of 5～6wt.％C. The reaction temperature was affected by the compaction pressure of the specimens, exhibiting the maximum values at 1600psi, respectively.

• Journal of Powder Materials
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• v.25 no.4
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• pp.309-315
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• 2018

In the present work, we synthesize nano-sized ZnO, $SnO_2$, and $TiO_2$ powders by hydrothermal reaction using metal chlorides. We also examine the energy-storage characteristics of the resulting materials to evaluate the potential application of these powders to dye-sensitized solar cells. The control of processing parameters such as pressure, temperature, and the concentration of aqueous solution results in the formation of a variety of powder morphologies with different sizes. Nano-rod, nano-flower, and spherical powders are easily formed with the present method. Heat treatment after the hydrothermal reaction usually increases the size of the powder. At temperatures above $1000^{\circ}C$, a complete collapse of the shape occurs. With regard to the capacity of DSSC materials, the hydrothermally synthesized $TiO_2$ results in the highest current density of $9.1mA/cm^2$ among the examined oxides. This is attributed to the fine particle size and morphology with large specific surface area.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.58-59
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• 2004

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1231-1231
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• 2006