• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.171-172
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• 2006

The effect of the preparation factors, such as the feeding mode and rate of raw materials, the reaction temperature and the surfactant on the size distribution of molybdenum trioxide particle were investigated by orthogonal test. The optimum conditions for the preparation of $MoO_3$ precursors are as following; opposite feeding fast, reaction temperature of $60^{\circ}C$ and adding dispersant.

• Proceedings of the Korean Society of Life Science Conference
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• 2001.02a
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• pp.59-59
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• 2001

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.422-427
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• 1995

In a stream of water sample, trace metal ions are quantitatively coprecipitated with Indium hydroxide and filtered. The filtered precipitate is continuously dissolved in 3 M nitric acid and introduced to ICP directly. The lead, cadmium, and copper are concentrated more than 10-fold and determined with ICP-AES at a sampling frequency of 10/hour. The detection limits are 2.89, 1.43,0.52 ppb for lead, cadmium, and copper respectively. Recoveries of lead, cadmium, and copper are 98.7, 94.3, and 104.5% respectively. The RSD values for three elements are about 3-5% currently.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.123-128
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• 1997

The effects of heat treatment on fatigue crack growth rates (FCGRs) of Inconel 690 have been investigated in terms of carbide morphology and grain size. Cycling tests in air at room temperature have shown that FCGR in low stress intensity factor range (ΔK) region can be effectively reduced by increasing the grain boundary carbide precipitate size and grain size. Decrease in FCGR is attributed to the crack tip blunting at the precipitates of grain boundary chromium carbides.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.378.2-378.2
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• 2002

Phellinus linteus has been used as anti-tumor and immuno stimulating agents in folk remedies. From precipitate of MeOH ex. by activited guided fractionation. 5.8-epidioxy ergosta-6.22-dien-3ol. palmitic acid. linoleic acid, and methyl linolate. 3.4-dihydroxybenzoic acid methylester and 4-(3'4'-Dihydroxyphenyl)-3-butene-2one were isolated. DPPH method was used to examine of antioxidative activity of the isolated compounds. As the result, 3.4-dihydroxybenzoic acid methylester, and phenolic compound. 4-(3'4'-Dihydroxyphenyl) -3-butene-2one were found to be a scavenger of 1,1-diphenyl-2-picrylhydrzyl radical. (omitted)

• Journal of the Korean Chemical Society
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• v.40 no.8
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• pp.535-541
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• 1996

In preparation of fine alumina powders with use of vesicle, the effect of variation of pH in extravesicular dispersion system to mechanism of precipitation and shape and size distribution of precipitate was investigated. The results of observation by TEM and turbidimeter were obtained as follows. Reaction between aluminum ion and hydroxyl ion to produce precipitate within vesicle was initiated at pH 11.4 and spherical fine precipitates, about 50 nm size, were formed at pH 12.0. About pH 12.3, size of precipitates in vesicle grew twice as great as those formed below pH 12.0 because of the agglomeration and coalescence of vesicleswith time.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.13-23
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• 2004

The characteristics of cesium and cobalt removal from soil around the TRIGA reactor using the electrokinetic method were analyzed and a device to restrain the pH increase in the soil column was suggested. When a NaCl solution was used as the electrolyte to raise the electric field strength, a precipitate was formed in the cathode in the soil column, resulting in a low removal efficiency. Thus, an acetate buffer solution (compound solution of $CH_3COONa$ and $CH_3COOH$) was injected into the soil column and acetic acid was periodically infected into the cathode reservoir to restrain any pH increase. Many $Cs^{2+}$ and $Co^{2+}$ ions were transferred by electromigration rather than electroosmosis during the initial remediation period, and no precipitate was formed in the soil column. 96% of the total amount of cesium in the soil column was removed after 5.9 days, while 94% of the total amount of cobalt was removed. Furthermore, the residual concentrations predicted by the developed model were similar to those obtained by experiment.

• Progress in Superconductivity and Cryogenics
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• v.22 no.3
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• pp.7-12
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• 2020

Electromechanical properties of REBCO CC tapes are known to be limited by defects (cracks) that form in the brittle REBCO layer. These defects could be inherently acquired during the CC tapes' manufacturing process, such as slitting, and which can be initiated at the CC tapes' edges. If propagated and long enough, they are believed to cause critical current degradation and can substantially decrease the delamination strength of CC tapes. Currently, commercially available CC tapes from various manufacturers utilize different growth techniques for depositing the REBCO layers on the substrates in their CC tapes preparation. Their epitaxial techniques, unfortunately, cannot perfectly avoid the formation of particles, in which sometimes acts as current blocking defects, known as outgrowths. Collective research regarding the composition, size, and formation of these particles for various CC tapes with different deposition techniques are particularly uncommon in a single study. Most importantly, these particles might interact in one way or another to the existing cracks. Therefore, systematic investigation on the interactions between the cracks' development mechanism and particles on the REBCO superconducting layers of practical CC tapes are of great importance, especially in the design of superconducting devices. Here, a proper etching process was employed for the CC tapes to expose and observe the REBCO layers, clearly. The scanning electron microscope, field emission scanning microscope, and energy-dispersive x-ray spectroscopy were utilized to observe the interactions between cracks and particles in various practical CC tapes. Particle compositions were identified whether as non-superconducting or superconducting and in what manner it interacts with the cracks were studied.

• KSBB Journal
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• v.14 no.2
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• pp.241-247
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• 1999

Experimental studies were carried out to optimize the culture conditions of Corynebacterium diphtheriae for the production of diphtheria toxin. A new media which does not contain any meat digest products was selected. The main ingredient of new medium was enzymatic digests of casein known as NZ-Case. In fermenter experiments, the toxin production was increased with the increase of cell growth. The optimum initial pH of media, air flow rate and agitation speed were 7.0, 0.22, vvm and 400 rpm, respectively. The contents of iron and calcium-phosphate precipitate were important for maximal cell growth and toxin production. The optimum concentration of iron was 0.3 mg/L and calcium-phosphate precipitate could serve in gradual supply of iron to maintain the optimal culture condition which is required for enhanced yield of toxin production. In potency test, the potency of toxoid from fermentor culture was higher than that from static culture. When diphtheria toxin is produced by fermentor culture, it is possible to produce higher levels of toxin and better toxoid quality in terms of safety, yield, productivity and immunity.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.391-397
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• 2014

Acid mine drainage occurrence is a serious environmental problem by mining industry; it usually contain high levels of metal ions, such as iron, copper, zinc, aluminum, and manganese, as well as metalloids of which arsenic is generally of greatest concern. It causes mine impacted soil pollution with mining and smelting activities, fossil fuel combustion, and waste disposal. In the present study, three bacterial strains capable of producing urease were isolated by selective enrichment of heavy metal contaminated soils from a minei-mpacted area. All isolated bacterial strains were identified Sporosarcina pasteurii with more than 98% of similarity, therefore they were named Sporosarcina sp. KM-01, KM-07, and KM-12. The heavy metals detected from the collected mine soils containing bacterial isolates as Mn ($170.50mg\;kg^{-1}$), As ($114.05mg\;kg^{-1}$), Zn ($92.07mg\;kg^{-1}$), Cu ($62.44mg\;kg^{-1}$), and Pb ($40.29mg\;kg^{-1}$). The KM-01, KM-07, and KM-12 strains were shown to be able to precipitate calcium carbonate using urea as a energy source that was amended with calcium chloride. SEM-EDS analyses showed that calcium carbonate was successfully produced and increased with time. To confirm the calcium carbonate precipitation ability, urease activity and precipitate weight were also measured and compared. These results demonstrate that all isolated bacterial strains could potentially be used in the bioremediation of acidic soil contaminated by heavy metals by mining activity.