• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1052-1063
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• 1998

The performance database of small-sized centrifugal compressors is needed for the design of high performance machines and also for the verification of design tools and analysis software. An impeller is designed, manufactured and tested. The effects of several parameters on the evaluation of performance are investigated and the performance test of parallel diffuser is also carried out. The proper estimation of static pressure, total temperature and blockage at the impeller exit is important for performance evaluation. 4 method in cooperation with 3-D calculation is suggested. The measured performances are in a good agreement with the predicted results. However, there are some discrepancies in efficiency.

• Journal of the Korea Furniture Society
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• v.19 no.1
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• pp.83-90
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• 2008

Gypsum-wood composites were made by introducing inorganic substances into wood using calcium chloride, first treating solution, and sodium sulfate, secondary treating solution, by double diffusion process under atmospheric pressure at room temperature. The process conducted as follows: water saturated specimens were soaked in calcium chloride solutions at several concentration. Then the specimens were soaked further in saturated sodium sulfate solution, and they were leached in flowing tap water for 24h. To attain sufficient weight percent gain (WPG) values, the suitable concentration of calcium chloride and soaking time in saturated sodium sulfate solution were 20% and 48h, respectively. Inorganic substances were produced mainly in the lumina of tracheides. It was made sure that these substances were dihydrate gypsum($CaSO_4$ $2H_2O$) by X -ray microanalysis (SEM-EDX). The composites had good fire resistance due to low heat transfer rate of gypsum formed in wood. However, the composites had little decay resistances, because they showed high weight losses by test fungi attacks.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.609-614
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• 2005

Gas hydrates are ice-l ike sol id compounds that are composed of water and natural gas. All common gas hydrates belong to the three crystal structures that are composed of five polyhedral cavities formed by hydrogen bonded water molecules and stable in specific high pressure and low temperature conditions. Gas hydrates contain large amounts of organic carbon and widely occur in deep oceans and permafrost regions, and they may therefore represent a potential energy resource in the future. United States and Japan perform the national R&D programs for the commercial production of gas hydrates in 2010's. The study on gas hydrates are also important for exploration and development of natural gas in the regions where gas hydrates are accumulated and could be formed. Although their global abundance is debated, they play an important role in global climate change since methane is a 50 times more effect ive greenhouse gas than carbon dioxide. Natural gas hydrates also form a possible natural hazard if rapidly dissociated and can cause slides and slumps and in the marine environment associated tsunamis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1395-1400
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• 2007

Tire flat spot is a deformation which occurs around the contact patch during long-period parking and does hardly recovered even after driving. The deformation makes a tire self-excited and ride comfort gets worse. In this study, it is shown that the flat spot can be evaluated by measuring change in radial run out or force. Its effects on vibration at vehicle floor and steering wheel are also revealed. Finally it is shown that the flat spot is likely to occur if the inflation pressure is low and the tire is suppressed by a heavy load at a high temperature.

• Biomolecules & Therapeutics
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• v.5 no.1
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• pp.74-81
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• 1997

DA-5018(N-(3-(3, 4-dimethylphenyl)propyl)-4-(2-aminoethoxy)-3-methoxyphenylacetamide) is a new capsaicin derivative under development as topical analgesic agent. The general pharmacological properties of DA-5018 on central nervous, cardiovascular, gastrointestinal and other organ systems were studied in experimental animals. DA-5018 cream (0.3%) had no effects on behavior, hexobarbital-induced sleeping time, body temperature, spontaneous activity, blood pressure, heart rate, intestinal charcoal propulsion, urine volume and electrolyte excretion even at a high dose of 2000 mg/kg in rats. In addition, DA-5Ol8 cream had little skin irritation compared to Zostrix-HP (capsaicin, 0.075%) cream in rabbits. In isolated guinea pig tissue studies, DA-5018 increased the contractility of trachea and ileum and also increased sinus rate of atrium in a range of 10^{-8}-10^{-5}$$ M, but its efficacy as a agonist was weak. These results suggest that DA-5018 cream might be used topically without serious side effects.

• Biomolecules & Therapeutics
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• v.5 no.3
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• pp.292-298
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• 1997

General pharmacological properties of ι-muscone, the major component of musk, were investigatedin mice, rats and guinea pig. The administration of ι-muscone (1, 10, 100 mg/kg, p.o.) in mice had no effects in general behaviors, and no influences on analgesic actions and normal body temperature. Muscle relaxant action, intestinal propulsion and gastric secretion were not observed even at the high dose of 100 mg/kg. ι-Muscone (1, 10, 100 mg/kg, p.o.) given to conscious rats showed no effect on mean blood pressure and heart rate. It showed no direct effect at 2.4$\times$10.3 mg/ml and 2.4$\times$10-2 mg/ml in isolated uterus of rats and ileum of guinea pig, and also had no inhibition of contraction induced by oxytocin and histamine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1168-1170
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• 2005

Nanoimprint Lithography(NIL) has increasingly been recognized as a key manufacturing technology for nanosized feature. One of the most important task for nanoimprint lithography is to provide the imprinting stamp with low price. The Stamp fabricated with Si based material by e-beam lithography, RIE is extremely expensive and its throughput is very limited and PDMS replica is too soft to hold high imprinting pressure.(>5atm) In this study, we present the imprinting stamp which can be easily replicated from original mold and is based on PVC film. Replication of original Si mold to PVC film was done by Hot embossing technique, ($120^{\circ}C$ of Temperature, 20 atm applied) As small as 100nm patterns were successfully transferred into PVC film. The size of stamp was up to 100mm in diameter.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.1
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• pp.33-37
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• 2000

Properties of electrical discharge in flames and influence of plasma electrons on gas neutrals are investigated by making use of the ionization cross section of air. Frames have three distinctive features. They are hot, emit light and are weakly ionized. We investigate influence of these three characteristics of flames on the electrical breakdown. It is found that the breakdown electric field in flames is inversely proportional to the flame temperature T$\_$g/, thereby easily generating plasmas in flames. A swarm of low-energy electrons in flames would allow a significant population of electronically excited states of flame molecules to be formed. Therefore, the analysis shows that the electronic excitation of flame molecules may also considerably reduce the breakdown field. Plasma electrons generate atomic oxygen by the electron attachment of oxygen molecules in high-pressure flames. These oxygen atoms are the most reactive radicals in flames for material oxidation.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.59-65
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• 1999

Ignition of $NH_3-O_2-Ar$ mixtures have been studied behind reflected shock waves over the temperature range of 1600-2300 K and the pressures in the range of 1.1-1.6 atm. The pressure profile and the radiation emitted behind the shock waves have been monitored to give empirical correlations between ignition delay times and the mixture concentrations with the experimental conditions. On the basis of this data, several kinetic mechanisms proposed for ammonia oxidation at high temperatures have been tested. The ignition delay times obtained from the mechanism proposed by Miller and Smook were in good agreement with our experimental results.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.418-424
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• 1996

(Ti.W)C complex carbide was synthesized by self-propagating high temperature synthesis (SHS) chemical furnace. Attempt to find the optimal condition for synthesis of (Ti.W)C the effects of molar ratio of Ti:W:C on the synthesized powders and mechanical properties were investigated, Optimum molar ratio of these synthe-sized powder was Ti:W:C=0.7:0.2:1.0 The bulk density M,O.R Hardness Fracture toughness of (Ti.W)C complex carbide sintered at 200$0^{\circ}C$ for 60 min by hot-pressing under the pressure of 20 MPa were 7.6g/cm3, 475 MPa, 17,.7 GPa respectively.