• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1271-1272
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• 2006

The vacuum infiltration method is one of the composite producing methods. There are several parameters in composite production by vacuum infiltration. One of them is particle size of reinforcement in particulate reinforced composites. In this study, MgO powder and Al were used as reinforcement and matrix respectively. MgO powders with different size and amount to give same height were filled in quartz tubes and liquid metal was vacuum infiltrated into the MgO powder under same vacuum condition and for same time. Infiltration height was measured and microstructure and fracture behavior of composite were investigated. It has been found that infiltration height and fracture strength were increased with particulate reinforcement sizes. It has also been determined that molten metal temperature facilitates infiltration.

• YAKHAK HOEJI
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• v.36 no.5
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• pp.455-459
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• 1992

Haemophilus K-12 producing novel sulfotransferase was isolated from mouce intestinal flora. The enzyme catalyzed the transfer of sulfate group from p-nitrophenylsulfate to phenolic compounds. The optimum medium condition for the sulfotransferase production was 0.2% sucrose, 1% yeast extract, $Na_{2}HPO_4$ and 0.5% NaCl. The enzyme production was induced by donor substrate, but was not by accepters. When p-nitrophenylsulfate was used as a donor substrate, 1-naphthol was best substrate, followed by phenol, p-acetaminophenol and tyramine.

• Journal of Plant Biotechnology
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• v.31 no.1
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• pp.37-41
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• 2004

In vitro culture system was established to induce multiple shoots of Thymus quinquecostatus Celak. by investigating the effects of cytokinins. Stem explants were cultures on MS medium supplemented with either five drfferent plant growth regulators or their combinations under light or dark condition. The most effective cytokininsource was the combination of BA 1.0mg/L and TDZ 0.1mg/L for producing shoots (6.05$\pm$1.51), zeatin 2.0mg/L and TEZ 0.1mg/L for elongating shoots (3.27$\pm$0.66cm) under the light condition. In addition the most effective cytokinin was 2-ip 2.0mg/L for producing shoots(5.20$\pm$1.81), zeatin 2.0mg/L for elongating shoots(5.64$\pm$1.24cm)under the dark condition. Overall, the average percent for in vitro shooting was greater than 89.58％.

• Membrane Journal
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• v.32 no.6
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• pp.475-485
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• 2022

The continuous excessive consumption of fossil fuels is causing global warming, climate, and environmental crisis. Accordingly, hydrogen energy attracts attention among alternative energies of fossil fuels, because it has the advantage of not emitting pollutants and not having resource restrictions. Therefore, various studies are being conducted on a water electrolysis system for producing hydrogen and a fuel cell system for producing electricity by using hydrogen energy as a fuel. In this study, 3D ionomer models were produced by reflecting the excessive water condition of an anion-conductive ionomer material, which is one of the core materials of water electrolysis systems and fuel cells. Finally, by analyzing the structural stability and performance of the ionomer under an excessively hydrated condition, we suggested a performance improvement factor in the design of an anion conductive ionomer, a key material for water electrolysis systems and fuel cells.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.1
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• pp.84-91
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• 1997

In producing moldings by using an injection mold, several variables such as the metal mold and the condition of injection molding should be selected properly in order to obtain good quality of moldings. In this study, focussed are the mechanical properties of injection moldings, since many researches on injection have been focussed mainly on the molding quality, injection pressure, and bulk temperature but the properties of injection moldings have not been studied extensively. The mechanical properties of present injection moldings can be improved simply by changing the molding material and the injection conditon without changind the metal mold. To have the final products meet the specified molding quality and mechanical properties at the same time, the bulk temperature of injection, pressure variation, volumetric shrinkage, stress, and cooling should be analized by CAE(computer aided engineering) after injection mold design. In this paper, the effects of dischare condition on mechanical properties of injection moldings are studied by testing the moldings which are injected by varying injection conditions.

• Journal of the Korean Ceramic Society
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• v.19 no.1
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• pp.44-50
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• 1982

Drawing optical fibers in a graphite furnace is one of the most convenient and economical means of producing optical fiber. Since the flaw formation on optical fiber is mainly due to dust contaminations during drawing and surface corrosion by water vapor penetration through coating layer, the tensile strength of optical fiber drawn in a graphite furnace is greatly inflenced by the drawing conditions. The important factors found in this investigation were preform treatment (fire polishing), furnace interior environment (dust contamination, inert gas flows), primary coating condition (resin curing temperature, coating materials, method, thickness) and fiber pulling condition (furnace temperature, drawing speed, pulling tension). The tensile strength at optimum drawing conditions turned out to be 5 ~ 6 GPa.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.981-986
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• 2003

In order to investigate the possibility of processing of brittle material by ball impact, the effects of boundary conditions about impact damage of soda-lime glass by small spheres were evaluated experimentally. It was investigated that crack appearance developed in soda-lime glass with boundary conditions of without sealing, single-sealing and double-sealing by impact velocity. The double-sealing was most effective in the development of perfect cone than other boundary condition. In case of double-sealing condition, PVC and Polyurethane sealing were more effective in producing a perfect cone formation than other sealing materials. The impact velocity range over which perfect cones were formed was influenced by both the contact area and diameter of impact particle.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.425-434
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• 2006

The process of producing 1,3-preprandiol by microorganism continuous cultivation would attain its equilibrium state. How to get the highest concentration of 1,3-propanediol at that time is the aim for producers. Based on this fact, an optimization model is introduced in this paper, existence of optimal solution is proved. By infinite-dimensional optimal theory, the optimal condition of model is given and the equivalence between optimal condition and the zero of optimality function is proved.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.59-64
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• 2020

In this paper, we found the solution using data based machine learning regression method to check the pore shape, to solve the problem of the experiment quantity occurring when producing scaffold with the 3d printer. Through experiments, we learned secured each print condition and pore shape. We have produced the scaffold from scaffold pore shape defect prediction model using multiple linear regression method. We predicted scaffold pore shapes of unsecured print condition using the manufactured scaffold pore shape defect prediction model. We randomly selected 20 print conditions from various predicted print conditions. We print scaffold five times under same print condition. We measured the pore shape of scaffold. We compared printed average pore shape with predicted pore shape. We have confirmed the prediction model precision is 99 %.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.102-110
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• 2014

It is a time to change the investment system for performances of co-producing according to development of the environment of performing arts in Korea. If we keep producing performances through the conventional method of the investment, we soon fall behind because production costs will increase by extension of the performance period. Investment companies generally require to the production company the investment principal guarantee as a condition for a investment. Producing companies have been producing performance with only ticket revenue and money of investment companies without their own money. Those two unreasonable things have raised a risk. So first of all, it is necessary to account marginal cost instead of average cost to decide more exactly open-running of performance. Second, it is necessary to change total cost as an investment parameter to production cost to avoid the unreasonable demands, such as a principal guarantee to production company. Therefore, we have to accept the budget planning of the United States to account the marginal cost and the production cost.