• Journal of Power System Engineering
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• v.9 no.4
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• pp.124-129
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• 2005

Copper oxide, CuO, are very important components include of high temperature super- conductors, and widely used. The properties of sintered materials were affected by the size and shape of copper oxide with starting materials in the solid-phase reaction. A homogeneous and fine CuO powder was prepared by thermal decomposition of the copper oxalate precursor. Copper oxalate was precipitated by the addition of copper nitrate solution to an oxalic acid solution. The influence of various factors such as temperature, pH, concentration as well as ultrasonic irradiation in the solution were investigated.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.143-152
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• 1995

This paper determines the allocation of computers and data files to minimize the sum of processing and communication costs which occur in processing jobs at each node. The problem of optimally configuring a distributed computer system belongs to the class of NP-Complete problems and the object function of this paper is nonlinear function and is hard to solve. This paper seeks the solution of distributed processing system by Tabu Search. Firstly, it presents the method of generating the starting solution proper to the distributed processing system. Secondly, it develops the method of searching neighborhood solutions. Finally, it determines the Tabu restriction appropriate to the distributed processing system. According to the experimental results, this algorithm solves a sized problems in reasonable time and is effective in the convergence of the solution. The algorithm developed in this paper is also applicable to the general allocation problems of the distributed processing system.

• Bulletin of the Korean Chemical Society
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• v.21 no.8
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• pp.817-822
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• 2000

Crack-free hard coating siIica films were prepared by sol-gel processfrom twokinds of silicon alkoxide (tetra-ethoxysilane and methyltrimethoxysilane) and two kinds of alcohol (methanol and isopropyl alcohol) with an acid catalyst,acetic acid. A silicate framework of the precursor solution was investigated by infrared spectros-copy (IR) in the process of hydrolysis and condensation. Theextent of the condensation in the intermediates was elucidated by gel permeation chromatography (GPC) and 29Si-NMR spectroscopy. The hard coating films werecharacterized by IR,scanning electron microscope (SEM), thermo gravimetric analyzer (TGA) and dif-ferential scanning calroimeter (DSC). The synthetic condition for the crack-free and transparent silica film for-mation was optimized interms of starting materials for the precursor solution as well as preparation method of the silica film.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.2
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• pp.121-129
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• 1996

The solubility of Ti in Al matrix was determined by X-ray diffraction method on two different mechanical alloying systems, i.e Al+$Al_3Ti$ and Al+Ti alloys. Starting powder compositions of two systems were chosen for final volume fraction of $Al_3Ti$ phase being 25%. The solubility of Ti in ${\alpha}$-Al was estimated by the lattice parameter measurement of Al. For Al+$Al_3Ti$ mixture, it appeared that some of $Al_3Ti$ particles decomposed during milling and maximum solubility of Ti in Al was about 0.99%. The majority of $Al_3Ti$ particles were dispersed uniformly in Al matrix, having approximate size of 100~200 nm. On the other hand, higher Ti solubility of 1.24 wt.% was found in Al+Ti system, with starting composition of Al+10 wt.%Ti. After 15 hours of milling, Ti phase was identified as 20 nm sized particles embedded in Al matrix. The annealing of mechanically alloyed powders from Al+$Al_3Ti$ and Al+10 wt.%Ti systems was followed in the temperature range of 200 to $600^{\circ}C$ to study thermal stability of supersaturated solution of Al(Ti). After annealing, the lattice parameter of Al reverted back to that of pure Al, and the peak intensity ratio of $Al_3Ti$/Al was increased more than the original value before annealing. These results suggest that Ti dissolve into alpha-Al solutions during milling, and by annealing, $Do_{22}-Al_3Ti$ phase forms from Al(Ti) solution.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.905-912
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• 1995

Influences of the starting salts on the phase and morphology of the Pb(Zr, T)O$_3$powders prepared by ultrasonic spray pyrolysis were studied. The Phases of the Powders Prepared from the combination of metal nitrate(or oxynitrate), acetate(or oxyacetate), and alkoxide were the Pb(Zr, Ti)O$_3$with or without minor PbTiO$_3$. The pores on the surface of the spherical particles increased with the nitrate content in the starting solution and their formation was thought to result from the decomposition characteristics of metal nitrate. Pb acetate, Zr oxyacetate, Ti oxynitrate, and Ti (isopropoxide+acetylacetonate) was suitable as the starting salts for the preparation of Pb(Zr, Ti)O$_3$powders by ultrasonic spray pyrolysis in the viewpoint of the phase and morphology of the powders.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.851-860
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• 1990

The hydrolysis-precipitation reaction of mixed aluminum salt solutions of aluminum sulfate, aluminum nitrate, and urea has been investigated to obtain narrow-sized and unagglomerated fine spherical precipitates of aluminum hydroxide required for coating core particles. The hydrolysis-precipitatin reaction could be controlled to be appropriate to coating processes by usign urea as a pH control-agent. As the concetration of total Al3+ ion and the molar ratio of SO42-/Al3+ in starting solutions became smaller and also as the vol. ratio of water/solution for hydrolyzing mixed aluminum salt solution became larger, the morphology of precipitates tended to be more unagglomerated and spherical, while their size(0.5longrightarrow0.05${\mu}{\textrm}{m}$) to be smaller. The optimum hydrolysis condition for coating processes was to hydrolyze the mixed aluminum salt solution, in which the molar ratio of SO42-/Al3+ was 0.75, while the amount of water corresponding to the vol. ratio of water/solution of 15. The precipitate was the aluminum hydroxide which sulfate ions were strongly adsorbed on and the maximum yield in the hydrolysis-precipitation reaction was about 20%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.242-243
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• 2005

In this study, (La,Sr)$MnO_{3+\delta}$ powder used cathode material for SOFC was synthesized with precursor by GNP and the properties of powder, crystal phase, electric properties and deoxidization properties with precursor were investigated. The synthesis powder was prepared when oxidant/fuel mole and pH were 1 and 1, respectively and the synthesis powder was synthesized by GNP method using nitrate solution or oxide solution as precursor. Deoxidization peak of the nitrate solution was appeared lower temperature than the oxide solution, at $450^{\circ}C$. In this result, synthesis (La,Sr)$MnO_{3+\delta}$ powder using nitrate solution with Mn excess was suitable cathode material for SOFC due to had higher deoxidization properties. Also synthesis (La,Sr)$MnO_{3+\delta}$ powder according to precursor had difference electrical conductivity according to influence sintering density and crystal phase with precursor. Specially, the synthesis method and starting material had effect on deoxidization properties for SOFC.

• Journal of Chest Surgery
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• v.21 no.1
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• pp.36-47
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• 1988

610 cases of open heart surgery was performed in the Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital from July 1981 to September 1987. The clinical data was summarized as follows: 1. The age distribution of congenital heart surgery patients was 2 to 41 years old [mean; 13.2 years] and surgery for acquired heart disease was 10 to 57 years old [mean: 32.8 years]. 2. There were 389 cases [63.8%] of acyanotic congenital heart anomalies, 63 cases [10.3%] of cyanotic congenital anomalies and 158 cases [25.9%] of acquired heart disease. 3. For myocardial protection, Bretschneider and potassium glucose solution had been used as cardioplegic solution and then since 1983, GIK solution has been used with repeated infusion method once for every 20 to 30 minutes of time interval after starting initial cardioplegia during operation with excellent results. 4. The ingredient of the priming solution is Hartmann`s solution, sodium bicarbonate, mannitol, potassium chloride, fresh ACD whole blood, calcium chloride, heparin and dexamethasone. 5. There were 96 cases [15.7%] of mild hypothermia, 333 cases [54.6%] of moderate hypothermia and 181 cases [29.7%] of intermediate hypothermia. 6. The mortality rate was 2.3% [9 out of 389 cases] in acyanotic congenital heart disease, 36.5% [23 out of 63 cases] in cyanotic congenital heart disease and 10.8% [17 out of 158 cases] in acquired heart disease, with overall mortality rate of 8.0% [49 out of 610 cases].

• Journal of Animal Environmental Science
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• v.13 no.1
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• pp.29-34
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• 2007

This study was conducted to develop a reclaimer of the vehicle disinfector to be used at livestock fm. The reclaimer was mainly consisted of ball-valves, geared motors and one-chip processor, and the purpose of the system was to prevent liquid freezing as well as decrease environmental pollution of antiseptic solution. The properly spraying pressure of the vehicle disinfector was found over 1.96 MPa at 1m of the spraying range. While certain amount of the antiseptic solution remained in the injection-pipes, the spray starting time was found not making any significant effect on the remained amount of the antiseptic solution. The amounts of the antiseptic solution remained in the injection-pipes were 50 ml and 270 ml in average, respectively with and without the use of the reclaimer. The reclaimer was the most effective when the connection of the injection-pipe and sprayer line was located below the side-injection-pipe and then connected to the injection-pipe located at the bottom of vehicles.

• Progress in Superconductivity and Cryogenics
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• v.13 no.4
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• pp.18-21
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• 2011

In this work, the yttrium oxide($Y_2O_3$) thin films as the buffer layer were prepared by the simple solution coating and reel-to-reel process on an unpolished metal tape substrate. The $Y_2O_3$ thin films were successfully synthesized by the hydrolysis of yttrium acetate. We have studied the improvement of surface roughness with the concentration of solution(0.1 M, 0.4 M, M) and the number of coatings. The planarization by solution coating process is simple in comparison with the existing polishing process, and it is eco-friendly, and has the benefits of low cost process. The thickness of $Y_2O_3$ films was increased with the $Y_2O_3$ concentration in the solution, and the surface became smoother with the number of coating cycles. Using this process, we have achieved 1.2 nm RMS roughness from a starting roughness of over 31 nm on 25 ${\mu}m^2$ area.