• Korean Journal of Animal Reproduction
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• v.24 no.2
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• pp.163-170
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• 2000

This study was conducted to examine the effects of recombinant Bovine Somatotropin (rBST), vitamin E(Vit. E) and selenium (Se) administration on the blood chemical values and hormone concentrations of serum in Hanwoo sires. Hanwoo sires were randomly assigned to five groups; 1) control, 2) rBST,0.09mg/kg body weight (BW), 3) Vit E, 1,500IU/kg BW, 4) Se 0.1mg/kg BW, 5) Vit E, 1,500IU plus Se 0.1mg/kg BW. rBST, Vit. E and Se for each experimental group were given 6 times at 15 days interval by intermuscular injection. Blood samples were collected ten times for experimental periods and separated the serum by centrifugation and stored into deep freezer. The concentration of albumin was the highest in Se group than those of any other groups (P＜0.05) and Vit. E plus Se group was significantly higher than in the control and rBST groups (P＜0.05). The concentrations of blood urea nitrogen (BUN) and creatinine were significantly higher in rBST group than any other groups (P＜0.05). The concentration of total protein in rBST, Se and Vit. E plus Se groups were significantly higher than in control group (P＜0.05). The concentrations of calcium, cholesterol,, glucose, inorganic phosphorus and triglycerides in serum were not difference in all experimental groups (P＞0.05). The concentration of estradiol was slightly higher in Se and Vit. E plus Se groups than those of any other groups, but not significantly difference among the experimental groups (P＜0.05). The concentration of testosterone was not affected by the administration of rBST, Vit. E and Se.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.665-675
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• 2010

The effects of chemical binders (ladle slag, ordinary portland cement (OPC), hydroxyapatite and calcium hydroxide) on the solidification/stabilization of heavy metals (Cd, Cu, Ni, Pb, Zn) in sewage sludge were evaluated by chemical leaching tests such as EDTA extraction, TCLP and sequential extraction. The results of EDTA extraction showed that heavy metal concentrations in sewage sludge were highly reduced after solidification/stabilization with slag, cement or calcium hydroxide. However, EDTA interrupted solidification/stabilization of heavy metals by hydroxyapatite. The TCLP-extracted heavy metal concentrations in sewage sludge after solidification/stabilization with chemical amendments were highly reduced. However, Cu concentration in the sewage sludge solidified/stabilized with slag, cement or calcium hydroxide increased because the pH of TCLP solution was higher than 7. Mixtures of sludge 1 : slag 0.2 : calcium hydroxide 0.1 (wt ratio) showed the least leachability in batch TCLP and EDTA extraction. The results of sequential extraction (SM&T, formaly BCR) indicated that the distribution of heavy metals changed from exchangable and carbonate fractions to strongly bound organic fraction. It was found that maximum leachate concentrations of Ba, Cd, Cr and Pb from sewage sludge amended with slag and calcium hydroxide were far below US EPA TCLP regulations.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.73-79
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• 2008

In order to apply for transparent conductive oxide(TCO), we deposited ZnO thin films on the glass at room temperature by RF magnetron sputtering method. Deposition conditions for high transmittance and low resistivity were optimized in our previous studies. Under the deposition condition with the RF power of 200 W, target to substrate distance of 30 mm and working pressure of 5 mTorr, highly conductive($7.4{\times}10^{-3}{\Omega}cm$) and transparent(over 85%) ZnO films were prepared. Highly oriented ZnO film in the [002] direction were obtained with specifically designed ZnO targets. Systematic study on dependence of deposition parameters on electrical and optical properties of the as-grown ZnO films were mainly investigated in this work. And for application tests using these films as transparent conductive oxide anodes, wet chemical etching behaviors of ZnO films were also investigated using various chemicals. Wet-chemical etching behavior of ZnO films were investigated using various acid solutions. The concentrations of these different acid solutions were controlled to study the etching shapes and etching rate. ZnO films were anisotropically etched at various concentrations and wet etching led to crater-like surface structure. Also we firstly found that the etching rate and etching shapes of ZnO films strongly depended on the etchant concentrations (i.e. pH) and the etching rate is exponentially decreased with increasing pH values regardless of the acid etchants.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.623-630
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• 2006

The slag viscosity is an important factor determining the operation temperature of entrained flow type of gasifiers. The temperature of critical viscosity, $T_{cv}$, for 5 crystalline slags was predicted by empirical models and FactSage equilibrium calculations, and the validity of each method was tested. Two empirical models were employed: one using $T_h$ from the ash fusion test, and the other using the concentrations of 5 major components. The first model using $T_h$ over-predicted $T_{cv}$ by $20{\sim}100^{\circ}C$, while the model based on the slag composition under-predicted $T_{cv}$ by $80{\sim}120^{\circ}C$. In the equlibrium calculations, $T_{cv}$ was obtained from the liquidus temperature. When the 4-major component concentrations were used in the calculation, the predicted temperatures were higher than the observed. The liquidus temperature was very sensitive to the concentrations of minor components, and the addition of MgO and $Na_2O$ lowered the liquidus temperature. The results with 4 major and 3 minor components most closely described experimentally observed $T_{cv}$. In the case that a chromia refractory was used, it was shown that $Cr_2O_3$ concentration in the slag also needs to be included for more accurate prediction of $T_{cv}$.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.143-156
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• 2015

The literature data of the mass concentrations of TSP, $PM_{10}$, and $PM_{2.5}$, and chemical composition of $PM_{2.5}$ (sulfate, nitrate, ammonium, OC, and EC) from 1985 and 2013 at Seoul were collected and the temporal trends were discussed in relation with the policy directions. Generally, the mass concentrations of TSP, $PM_{10}$, and $PM_{2.5}$ at Seoul have showed decreasing trends. However, it is not clear what might be the major reason(s) for the trends. The concentrations of ionic component in $PM_{2.5}$ showed different trends, sulfate being reduced during the 1990s but no trend during the 2000s. The concentrations of nitrate and ammonium were increasing during the 2000s. The concentrations of OC show no apparent trend while that of EC decreased. Further policy directions are suggested based on the temporal trends of the chemical composition in $PM_{2.5}$.

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.165-169
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• 1969

On the electrolytic preparation of sodium chlorate, lead dioxide anode, instead of graphite was tested to find out the characteristics for current efficiency and life in various conditions. The results obtained are summerized as follows; 1. The current efficiency is slightly increased with the anode current density, until 25A/$dm^2$ 2. The higher the current concentrations. the lower current efficiencies are observed, particularly in case of both not-adding the potassium dichromate and large current concentration of more than 50A/l 3. The current efficiency may be improved linearly as the both temperature is raised.

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.29-32
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• 2007

Zinc gallate, $ZnGa_2O_4:Mn^{2+}$ co-doped with different concentrations of $Mg^{2+}$ (0.001- 0.5 mol%) was prepared by solid state synthesis method. These compositions were investigated for their photoluminescence and cathodoluminescence properties. The optimized composition $Zn_{0.990}Mg_{0.005}Ga_2O_4:Mn_{0.005}$ shows higher luminescence intensity compared to the parent phosphor. The intense green emission peak was found at 504 nm. The $Mg^{2+}$ doping does not affect much the decay time. It remains <10 ms for these compositions which make them potential candidate for application in TV screens.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.618-621
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• 2005

In this study, the phenomena of hydrate formation and inhibition were investigated according to varying the concentrations using methanol and ethylene glycol as chemical additives. The results reveal that the used additives display better inhibition effects compared to pure water by decreasing the formation temperature and the inhibition performance of methanol is superior to that of ethylene glycol. As a conclusion, the plugging phenomena of flowline in natural gas product ion. subsea and frozen field pipelines can be predicted by examining the hydrate formation and inhibition conditions. Specifically, the results of this study can be applied to the selection of the prevention criteria and method of hydrate formation.

• Carbon letters
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• v.12 no.2
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• pp.112-115
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• 2011

The scope of this work investigates the relationship between the amount of oxygen-functional groups and hydrogen adsorption capacity with different concentrations of phosphoric acid. The amount of oxygen-functional groups of activated carbons (ACs) is characterized by X-ray photoelectron spectroscopy. The effects of chemical treatments on the pore structures of ACs are investigated by $N_2$/77 K adsorption isotherms. The hydrogen adsorption capacity is measured by $H_2$ isothermal adsorption at 298 K and 100 bar. In the results, the specific surface area and pore volume slightly decreased with the chemical treatments due to the pore collapsing behaviors, but the hydrogen storage capacity was increased by the oxygen-functional group characteristics of AC surfaces, resulting from enhanced electron acceptor-donor interaction at interfaces.

• Korea-Australia Rheology Journal
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• v.12 no.3_4
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• pp.143-149
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• 2000

In this article, we considered shear-induced microstructure and rheological behavior of micellar solutions of cationic surfactant, cetylpyridinium chloride (CPC) in the presence of a structure-forming additive, sodium salicylate (NaSal). Shear viscosity, shear moduli and flow birefringence were measured as functions of the surfactant and additive concentrations. In the presence of NaSal, the micellar solution exhibited the non-linear rheological behavior due to the formation of supramolecular structures when the molar ratio of NaSal to CPC exceeded a certain threshold value. Flow birefringence probed the change in micelle alignment under shear flow. At low shear rates, the flow birefringence increased as the shear rate increased. On the other hand, fluctuation of flow birefringence appeared from the shear rate near the onset of shear thickening, which was caused by shear-induced coagulation or aggregation. These results were confirmed by the SEM images of in situ gelified micelle structure through sol-gel route.