• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.28-34
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• 1998

Powder metallurgy processes are able to form Net-Shape products and have been widely used in the production of automobile parts to improve its productivity. However, because of pores in powder products, the toughness of powder products are generally poor. Therefore, forged products are used in parts which suffer severe fatigue loads. In this paper, the choice of powder materials and production processes such as mixing, compaction, sintering, heat treatment to produce automobile spline hub are studied. Three type of materials are selected and processed and its microstructure and properties are investigated by tensile test, compression ring test, and impact test. Materials and processing methods are selected from the results. Finally, experimental spline hubs are manufactured by selected processes from selected powders and proved by torsional durability test.

• Journal of Powder Materials
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• v.25 no.5
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• pp.390-394
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• 2018

Metallic tantalum powder is manufactured by reducing tantalum oxide ($Ta_2O_5$) with magnesium gas at 1,073-1,223 K in a reactor under argon gas. The high thermodynamic stability of magnesium oxide makes the reduction reaction from tantalum oxide into tantalum powder possible. The microstructure after the reduction reaction has the form of a mixture of tantalum and magnesium oxide, and the latter could be entirely eliminated by dissolving in weak hydrochloric acid. The powder size in SEM microstructure for the tantalum powder increases after acid leaching in the range of 50-300 nm, and its internal crystallite sizes are observed to be 11.5 to 24.7 nm with increasing reduction temperatures. Moreover, the optimized reduction temperature is found to be 1,173 K as the minimum oxygen concentration is approximately 1.3 wt.%.

• Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.367-372
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• 2015

We investigated the effects of dietary supplementation of two types (powder or liquid) of propolis on innate immunity and disease resistance of olive flounder Paralichthys olivaceus against Edwerdsiella tarda. A total of 600 fish averaging 30 g were randomly distributed into 24 tanks in groups of 25. Three tanks were assigned to each of eight experimental diets: 0 (Control), 0.25, 0.5, 0.75 and 1 % propolis in powder form and 0.25, 0.5 and 1 % propolis in liquid form (PP0.25, PP0.5, PP0.75, PP1, LP0.25, LP0.5 and LP1, respectively). Fish were fed each experimental diet twice daily for four weeks to apparent satiation. At the end of the feeding trial, lysozyme and myeloperoxidase activities and total immunoglobulin level were significantly higher in fish fed the PP1 and LP0.5 diets compared to those fed the control diet. The PP1 diet was also associated with a significant increase in anti-protease activity compared to the control diet. After challenge with E. tarda, fish fed the LP0.5 diet showed numerically higher survival compared to the other groups. This study indicates that non-specific immune responses of olive flounder can be enhanced by dietary supplementation with powder and liquid forms of propolis, and that the optimal level would be 1% in powder form or 0.5% in liquid form. It seemed that growth performance and feed utilization are not affected by the propolis supplementation in diets for olive flounder.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.16 no.3
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• pp.38-67
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• 2003

The burn is acute skin injury caused by fire, hot water. steam. hot oil, sour and salty. It is occurred frequently in the daily life as well as oriental therapy like moxibustion therapy, physical therapy. Nevertheless, medical treatment of the burn is almost dependent on western cure. So we chose the oriental medicine textbooks and the oriental medicine journals that were dealing with the drugs, processing the drugs. peculiar treatment put first external cure. The results were as follows; 1. The burn is acute skin injury caused by fire, hot water, steam, hot oil, sour and salty. 2. The burn cause blisters, irritability and restlessness, nausea, dryness of mouth, constipation, in case of serious, coma, dyspnea and death. The early stage of the burn, blisters form by skin damage and they burst into skin ulceration from which pus issues, the latter term, the wound form scab and healed up. 3. In a light case, medical treatment of the burn was used external treatment by medicine for externalism use, in a serious case, it was used both as an internal remedy and medicine for outward application. Also in the early stage, it was careful of using the cold and cool medicine, as the process of healing, it was used alleviating pain, detoxicating, moistening the skin, growing muscle and skin, convergence, evacuating pus, regeneration of the tissue, strengthen the spleen and nourishing the stomach. 4. The external treatment medication is Herba Ephedrae Oil(麻油), Radix ET Rhizoma Rhei(大黃), Glauberitum(寒水石), Water(水), Pig OiI(猪油), Pig Fat(猪脂), Radix Angelicae Gigantis(當歸), Rhizoma Coptidis(黃連), Cortex Phellodindri(黃栢). The White of an Egg(鷄子淸), Raw Honey(生蜜), Honey(蜜), Wine(酒), Etc. It is mostly the cold and cool medications. 5. Soft extracted and powered dosage form in external treatment is much used. The soft extracted form(32times used) are mostly Chung Ryang paste(淸凉膏) and Fructus Papaveris paste(罌粟膏). The powered form(30times used) are mostly Bingsang Powder(氷霜散), Bosaenggugo Powder(保生救苦散), Sahwang Powder(四黃散). The others is much a various powder adding solvent. 6. If varicella stage, erosion after varicella stage, oozing stage and extreme pain stage, the powder adding solvent is much used. If little oozing stage. ulcering stage, scabing stage and a chronic stage, Soft extracted dosage form is much used. 7. The most many(26.65%) used method is that apply each medication power mixed water(水), wine(酒), honey(蜜) in a wounded part.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.924-938
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• 1998

Densification behavior of ceramic powder under cold compaction was investigated. Experimental data were obtained for zirconia powder and alumina powder under triaxial compression with various loading conditions. A special form of the Cap model was proposed from experimental data under triaxial compression for a yield function of ceramic powder. The proposed yield function was inplemented into a finite element program (ABAQUS) to study densification behaviors of zirconia and alumina powders under die compaction. The effect of friction between the powder and die wall was also investigated. Density distributions of powder compacts were measured and compared with finite element results.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.118-124
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• 2016

The purpose of this study is to analyze the rheology characteristics of insulating concrete for each type of insulation performance improvement material and utilize the result as preliminary data for optimal flow designing and pumping analysis. As a result, when lightweight aggregate was mixed, the yield stress decreased significantly, and in case of type 2, the combination of micro form cell admixture (MFA) and calcined diatomite powder (DM) showed the most ideal flow characteristics. In case of type 3, the combination of micro form cell admixture (MFA), calcined diatomite powder (DM) and lightweight aggregate (L) showed the best flow characteristics.

• Journal of Powder Materials
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• v.2 no.2
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• pp.158-164
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• 1995

Synthesis of the NiTi shape memory alloy using the thermal explosion mode of the self-propagating high-temperature synthesis has been investigated. The significant fractions of intermetallics phases were found to form at the Ti/Ni powder interface during the heating to the ignition temperature and seemed to influence the relative fraction of phases in the final products. As the heating rate to the ignition temperature was increased, the combustion temperature and the fraction of NiTi in the final reaction products were increased. The synthesis reaction under 70 MPa compressive pressure yielded a reaction product with 98% theoretical density.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.656-657
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• 2006

One append way of liquid state inhibitor was investigated, which putting V, Cr into W-Co composite solutions in the form of ionization. After spray drying and being calcined, W-Co composite oxides could come into being. Then taking fluidization techniques, well-proportioned W-Co composite powder compounded with inhibitor could be produced in the end.

• The Journal of the Korean dental association
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• v.54 no.5
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• pp.348-355
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• 2016

Ideal autogenous or allogenic bone graft materials should provide 1) stabilization of blood clot, 2) scaffolds for cellular proliferation and differentiation, 3) release of osteogenic growth factors, 4) appropriate resorption profile for remodeling of new bone. Teeth, especially dentin, mostly contain hydroxyapatite and type I collagen which are similar to bone, and could be valuable graft material. Clinically teeth are used as calcined or demineralized forms. Demineralized form of dentin can be more effective as a graft material. But a conventional decalcification method takes time and long treatment time may give negative effects to various osteogenic proteins in dentin. Author used a new clinical method to prepare autogenous teeth, which could be grafted into the removal defects immediately after extraction using vacuum ultrasonic system. The process could be finished within two hours regardless of the form (powder, chip or block). Teeth were processed to graft materials in block, chip, or powder types immediately after extraction. It took 120 minutes to prepare block types and 40 minutes to prepare powder. Clinical cases did not show any adverse response and the healing was favorable. Rapid preparation of autogenous teeth with the vacuum ultrasonic system could make the immediate one-day extraction and graft possible.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.589-595
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• 2000

Densification behavior of SiC powder was investigated under cold compaction. A special form of the Cap model was proposed from experimental data of SiC powder under triaxial compression. To compare with experimental data of SiC powder under cold compaction, the proposed constitutive model was implemented into a finite element program (ABAQUS). Finite element calculations from the Cam-Clay model and the modified Drucker-Prager model were also compared with experimental data of SiC powder. The agreements between experimental data and finite element results obtained from the proposed constitutive model are reasonably good. In die pressing, finite element results obtained from the Cam-Clay model and the modified Drucker-Prager model, however, show lower average density of SiC powder compacts compared to experimental data.