• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.844-851
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• 2004

Efficient mammalian erythropoietin (EPO)-expression systems are required for therapeutic applications. The accumulation of ammonia is a major problem in the production of recombinant proteins in cultured animal cells. To counter this problem we introduced the first two genes of the urea cycle, carbamoyl phosphate synthetase (CPSI) and ornithine transcarbamylase (OTC), into IBE Chinese Hamster Ovary (CHO) cells by stable transfection. The resulting cell line, CO5, had a higher growth rate and accumulated less ammonia per cell than the parental cell line, IBE. In addition, it produced 2 times more EPO than the parent, and the purified EPO contained a higher proportion of acidic isoforms with approximately 15% more sialic acid.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1724-1728
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• 2009

Severe acute respiratory syndrome coronavirus (SARS-CoV) helicase separates the double-stranded nucleic acids using the energy from ATP hydrolysis. We have measured ATPase activity of SARS-CoV helicase in the presence of various types of nucleic acids. Steady state ATPase analysis showed that poly(U) has two-times higher turnover number than poly(C) with lower Michaelis constant. When M13 single-stranded DNA is used as substrate, the Michaelis constant was about twenty-times lower than poly(U), whereas turnover numbers were similar. However, stimulation of ATPase activity was not observed in the presence of double-stranded DNA. pH dependent profiles of ATP hydrolysis with the helicase showed that the optimal ATPase activities were in a range of pH 6.2 ~ 6.6. In addition, ATP hydrolysis activity assays performed in the presence of various divalent cations exhibited that $Mg^{2+}$ stimulated the ATPase activity with the highest rate and $Mn^{2+}$ with about 40% rate as compared to the $Mg^{2+}$.

• Journal of the Korean Chemical Society
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• v.9 no.1
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• pp.16-22
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• 1965

The time-lag-effect of alkali salts on the gelation of sodium alginate-$CaSO_4{\cdot}$1/2 $H_2O$ is compared with Miyake's data, and then the formation rate of the elastics measured by the continuous method (an improved Schwedoff's method) and the change of rigidity with metallic oxides are studied as follows: (1) The gelation processes of sodium alginate and $CaSO_4{\cdot}$1/2 $H_2O$-aqueous sol are studied by measuring, continuously the increases of tensions ofsamples. (2) The time-lag-effect of $Na_3PO_4$ on the formation rate of the elastic gel is larger than that of $Na_2CO_3$, but the difference between the effects of the two alkali salts on the rate is found not so greater than predicted in Miyake's data. (3) Any regularities of the effect on the rate by metallic oxides are not observed. The increasing effects of the rates of $SiO_2$ and MgO are relatively large, and that of ZnO is relatively small. However, $Al_2O_3$, $Sb_2O_3$ and $TiO_2$show some decreasing effects. As a result it is noted that the regularities do not depend on the effect of oxide species and their amounts. (4) It is not found proportionality between the rigidity and the gelation rate. However, the increasing effect of the rigidity with the addition of metallic oxides can be observed. The rigidity increasing rate of MgO is the largest of them.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.803-810
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• 1998

We have studied the catalytic combustion of soot particulate over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxide. In addition, the reaction conditions, such as temperature, $O_2$ concentration, space velocity have been studied. The effect of $SO_2$ pretreatment and water introduced into reactants were also examined. In the $LaCoO_3$ catalyst, the partial substitution of alkali metals into A site enhanced the catalytic activity in the combustion of soot particulate and the activity was shown in the order : Cs>K>Na; In the $La_{0.6}Cs_{0.4}CoO_3 $; catalyst, the substitution of Fe or Mn showed no effect on the ignition temperature. The ignition temperature decreased with increasing $O_2$ concentration and contact time. The introduction of water into reactants feed decreased the ignition temperature and the pretreatment of $SO_2$ showed no effect on the catalytic activity.

• Resources Recycling
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• v.30 no.6
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• pp.36-42
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• 2021

Spent lithium-ion batteries are treated by reduction-smelting at high temperatures to recover valuable metals. Solvent extraction and precipitation of the HCl leaching solution of reduction-smelted metallic alloys resulted in a filtrate containing Ni(II) and a small amount of Si(IV). Adsorption and precipitation experiments were conducted to recover pure Ni(II) compounds from the filtrate. Si(IV) was selectively loaded onto polyacrylamide, but this method did not efficiently filter the solution due to an increase in viscosity. The addition of Na₂CO₃ as a precipitant to the filtrate led to the simultaneous precipitation of Ni(II) and Si(IV). However, it was possible to recover nickel oxalate with a purity higher than 99.99% by selectively precipitating Ni(II) with the addition of Na₂C₂O₄ as a precipitant.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.54-63
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• 2012

The purpose of this study is to examine the potential for reducing the environmental load and $CO_2$ gas when cement is produced by using cement substitutes. These substitutes consisted of blast furnace slag, red mud and silica fume, which were industrial by-products. The most optimum mix was derived when alkali accelerator was added to low carbon inorganic composite mixed with industrial by-product at room temperature. It is determined that hardened properties and the results of compressive strength tests changed based on CaO content, Si/Al, the mixing ratio and the amount of alkali accelerator, curing conditions and W/B. The results of test analysis suggest that the optimum mix of low carbon inorganic composite is CaO content 30%, Si/Al 4, the mixed ratio of alkali accelerator $(NaOH:Na_2SiO_3)$ 50g:50g, the amount of alkali accelerator 100g and W/B 31%. In addition, if contraction is complemented, low carbon inorganic composite with superior performance could be developed.

• Economic and Environmental Geology
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• v.28 no.6
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• pp.635-646
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• 1995

Mineralized zone in the Dongyang talc deposits occurs on the lowest dolomite member of the Hyangsanri Dolomite belonging to the Ogcheon Supergroup. Ore bodies are emplaced as pipe-like body along the axis of minor folds plunging $40^{\circ}$ to the west developed in these dolomite layers. Amphibolite and chlorite schist are found along the upper or lower contact of all ore bodies (Kim et al., 1963; Park and Kim, 1966). Following the recrystallization and silicification of dolomite, tremolite and tabular and leafy talc(I) of the earlier stage formed, and microcrystalline talc(II) formed in the later stage. Talc(l) and tremolite formed by the reaction between dolomite and the fluid. Whereas talc (II) formed by the reaction between dolomite and fluid, or by the reaction between early formed tremolite and fluid. During the early stage of mineralization, the fluid was the $H_2O-CO_2$ system dominant in $CO_2$, In the later stage, the composition of the fluid changed to $H_2O-NaCl-CO_2$system, and finally to the $H_2O-NaCl$ system. The pressure and temperature conditions of the formation of tremolite associated with talc(I) were 1,640~2,530 bar, and $440{\sim}480^{\circ}C$, respectively. The pressure and temperature condition of talc(II) ore formation was 1,400~2,200 bar, and $360{\sim}390^{\circ}C$, respectively. These conditions are much lower than the metamorphic pressure and temperature of the rocks from the Munjuri Formation located about 5 km to the noJ:th of Dongyang talc deposit ${\delta}^{13}C$ and ${\delta}^{18}O$ values of dolomite which is the host rock of the talc ore deposit are 2.9~5.7‰ (PDB), and -7.4~l6.8‰ (PDB), respectively. These values are little higher than those from the Cambro-Ordovician limestones of the Taebaeksan region, but belong to the range of the unaltered sedimentary dolomite. ${\delta}^{18}O$and ${\delta}D$ values of the talc from Dongyang deposit are 8.6~15.8‰ (vs SMOW), and -65~-90‰ (vs SMOW), respectively, belonging to the range of magmatic origin. These values are quite different from those measured in the metamorphic rocks of Munjuri and Kyemyungsan Formation. ${\delta}^{34}S$ value of anhydrite is 22.4‰ (CDT), which is much lower than ${\delta}^{34}S$ (30‰ vs COT) of sulfate of early Paleozoic period, and indicates the possibility of the addition of magmatic sulfur to the system. Talc ores show the textures of weak foliation and well developed crenulation cleavages. Talc ore deposit in the area is concluded as hydrothermal replacement deposit formed before the latest phase of the deformations that Ogcheon Belt has undergone.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.1
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• pp.54-61
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• 2016

Washing machine manufacturers typically advise consumers to maintain the relative humidity in the drum less than 80% for three days after the termination of a washing cycle in order to prevent bacteria proliferation. A vent installed in the back of a washing machine is used to release moisture to satisfy this condition. Up to now, the design and installation of the vent have been based on experiments without understanding its roles and physical phenomena. In this study, various CFD results are presented in order to explain the physical mechanism of moisture release in a washing machine. Two methods of moisture release (diffusion and convection) were studied; diffusion was found to be the dominant process in removing moisture. Experiments were also performed to validate this behavior. In addition, this study will aid in the efficient design of vents to keep the relative humidity low inside the drum.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.79-85
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• 2006

Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

• Membrane Journal
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• v.18 no.1
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• pp.35-43
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• 2008

In this study, we tried to solve membrane fouling with membranes made by fine nano-particle in MBR process. And we confirmed good fouling resistance in pilot test. In this test, we confirmed our membrane with titania out-standing quality by testing in the pilot long-term test by comparing to other company product. Our membrane keep up steadily $20{\sim}25 L/m^2{\cdot}hr$ high flux in $7,000{\sim}13,000mg/L$ MLSS high sludge concentration. In addition to this quality, we studied membrane flux character related membrane arrangement, membrane-air line arrangement, air-line hole size, cleaning solution concentration, treatment method, etc. Using the optimization of this additional parameter, we tried to search method of maximizing membrane quality.