• Journal of Life Science
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• v.15 no.3 s.70
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• pp.468-473
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• 2005

The coastal regions of Yeosu, the South Sea of Korea, has occurred annually the red tide which is caused by potentially ichthyotoxic dinoflagellate C. polykrikoides, with a wide avenue for exchange with oceanic waters and freshwater runoff from Sumjin river. We attempted to examine the variability in response to vertical migration and concentration of extracted DNA/RNA of C. polykrikoides exposed to salinity-stratified waters. The experimental aquarium of the 60 liter was employed to culture C. polykrikoides. One aquarium was supplied with only sea water, the other was consisted of sea water and freshwater. Experiment was conducted for 5 days. In experimental column (mixture of freshwater and sea water), salinity was maintained to 20 at upper and approximately 30 at bottom during the period of this study. The fluctuation with related to dissolved oxygen and pH was similar pattern to both columns. Chlorophyll a was significantly higher value at upper than bottom. During 24h, chlorphyll a on experimental column was extremely high on the top as soon as lighting, compared with control. With elapsed time, the gap between experimental and control columns was a little. In darkness, chlorophyll a was not significantly different between upper and bottom, most cells appeared to randomly distribute on column regardless of water layer. Fluctuation with related to concentration of extracted DNA and RNA based on ratio of absorbance of 260 and 280 nm in experimental column was higher at final day or diel migration than control. These results implied that a large volume of freshwater could be associated with influence of concentration of DNA and RNA, in particular, rapid upward movement caused massive fish kills as soon as sunset.

• Polymer(Korea)
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• v.36 no.5
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• pp.549-554
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• 2012

It was known that triphenyl phosphate wasn't homogeneously dispersed in HDPE/EPDM/boron carbide blends, which caused the decrease in mechanical properties. HDPE, EPDM, boron carbide, and triphenyl phosphate were blended with PE-g-MAH(polyethylene-graft-maleic anhydride) as a compatiblizer for improving the miscibility of triphenyl phosphate. Tensile strength of HDPE/EPDM/boron carbide blends decreased with increasing the contents of triphenyl phosphate for flammability. However, the mechanical properties of HDPE/EPDM/boron carbide/triphenyl phosphate blends increased by the addition of compatiblizer because triphenyl phosphate was homogeneously mixed in the blend system. The homogeneous dispersibility of triphenyl phosphate was confirmed by using scanning electron microscopy (SEM). Increased thermal stability and flammability derived from high miscibility of triphenyl phosphate were confirmed by the results of thermogravimetric analysis (TGA) and limiting oxygen index (LOI). A self-extinguishing HDPE/EPDM/boron carbide/triphenyl phosphate blend was successfully fabricated with more than 21% LOI.

• Polymer(Korea)
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• v.32 no.1
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• pp.63-69
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• 2008

The mechanical properties and morphologies of cellulose blends with two different additives were compared. Poly (vinyl alcohol) (PVA) of ethylene glycol (EG) were used as additives in the formation of cellulose blends through the solution blending. The properties of blends were varied with the additive content in the polymer matrix. The ultimate tensile strength and initial modulus of the cellulose blends were highest for a blend PVA content of 30 wt% and for a blend EG content of 10 wt%, respectively. Ternary blended systems of composition of cellulose/PVA (70/30=w/w)/EG were also prepared by the solution blending method with different EG contents. The mechanical properties of these systems were found to be optimal for EG contents of up to 40 wt%. The mechanical properties of the cellulose ternary blend films were superior to those of the cellulose binary blend films. The oxygen permeability transmission rate ($O_2TR$) monotonically decreased with increasing EG content in the ternary blend films. Overall, the mechanical properties of the cellulose blend films were found to be better than those of pure cellulose films.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.4
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• pp.239-244
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• 2004

In order to enhance an oxidation resistance of the pure uranium metal under air condition, a small quantity of niobium(Nb) which is known to mitigate metal oxidation is added into uranium metal as an alloying element. A simulated metallic uranium alloy, U-Nb has been fabricated and then oxidized in the range of 200 to $300^{\circ}C$ under the environment of the pure oxygen gas. The oxidized quantity in terms of the weight gain(wt%) has been measured with the help of a thermogravimetric analyzer. The results show that the oxidation resistance of the U-Nb alloy is considerably enhanced in comparison with that of the pure uranium metal. It is revealed that the oxidation resistance of the former with the niobium content of 1, 2, 3, and 4 wt% is : 1) 1.61, 7.78, 11.76 and 20.14 times at the temperature of $200^{\circ}C$ ; 2) 1.45, 5.98, 10.08 and 11.15 times at $250^{\circ}C$ ; and 3) 1.33, 4.82, 8.87 and 6.84 times at $300^{\circ}C$ higher than that of the latter, respectively. Besides, it is shown that the activation energy attributable to the oxidation is 17.13~21.92 kcal/mol.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.20-26
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• 2008

This study investigated the antioxidative effect of mugwort (Artemisia vulgaris L.) extracts in hairless mouse skin from oxidative stress induced by UV-irradiation. After topical application on hairless mouse back with basic skin lotion group (control), ascorbic acid group (AA-0.5%, AA-1.0%, AA-2.0%, and AA-5.0%), and mugwort extract group (ME-0.5%, ME-1.0%, ME-2.0%, and ME-5.0%), the animals were irradiated to increasing doses of UVB (60 $mJ{\sim}100$ mJ) for 4 weeks. Hydrogen peroxide of hairless mouse skin homogenate significantly decreased in 2% (p<0.05) and 5% (p<0.05) of ME and AA groups. Hydroxyl radicals were decreased significantly in both of 2% and 5% ME groups as compared to AA groups (p<0.05). Oxidative stress levels deduced by oxidized protein contents were greatly decreased ($14.6{\sim}18.5%$) in all ME treatment groups, while only at 2% of AA treatment group. Lipid peroxide contents were greatly inhibited in all ME and AA treatment groups (p<0.01). Application of ME significantly increased catalase activity, over 25% in all mugwort and AA groups. Glutathione peroxidase activities were increased up to $20.5%{\sim}32.8%$ in 2.0% and 5% ME groups, whereas it increased in all AA groups. These results suggested that mugwort extract was more effective than that of ascorbic acid in protecting hairless mouse skin from photo-irradiation, and can be used as an potential anti-aging cosmetic ingredients.

• Journal of Ginseng Research
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• v.23 no.3 s.55
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• pp.182-189
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• 1999

For the determination of anti oxidative effects of Korean red ginseng extracts, 100 mg/kg body weight of paraquat(1,1-dimethyl-4,4-bipyrimidinium dichloride) was injected to peritoneal cavity of 6 weeks 23-27 g of ICR mail mice which were pretreated with 200 mg/kg body weight of korean red ginseng extracts(total saponin, water extracts, alcohol extracts, lipophilic extracts) and ascorbic acid for 5 days. Most of mice died of paraquat toxicity within 4 days except only $30\%$ of ascorbic acid group. The hepatic total-SOD activity in liver was highest in ascorbic acid group and lipophilic ginseng extracts group next (p<0.0l). The level of hepatic hydroperoxide was lowest in the order of in alcohol extracts group, lipophilic extracts group and ascorbic acid group (p<0.0l). The highest catalase activity was induced by ascorbic acid followed by water extracts and lipophillic extracts (p<0.01). Finally, the lipid peroxidation level (malondialdehyde:MDA) was the lowest in water extracts group and ascorbic acid next (p<0.01). The highest MDA level was appeared in praquat group and next total saponin group next. In conclusion, the order of effectiveness of antioxidants was found to be ginseng water extracts> ascorbic acid> lipophillic extracts> other ginseng extracts. It was also found that any predominant antioxidant was not effective evenly to all of antioxidant test.

• Elastomers and Composites
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• v.40 no.3
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• pp.188-195
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• 2005

Chemical and physical changes and the contents of functional groups in the carbon black surface after the ozone treatment was investigated using elemental analysis, pH, tint strength, DBP, $N_2SA$, IA, and acid-base reaction. As the treatment time was increased, surface structure, particle size and surface area of carbon black did not change, while surface oxygen contents increased, and pH decreased and then saturated after $1{\sim}2$ hour. The contents of carboxylic, lactone, hydroxyl, and carbonyl groups were analyzed with four bases such as $NaHCO_3,\;Na_2CO_3,\;NaOH$, and $NaOC_2H_5$. Before oxidation, the carbonyl group was dominantly present on the surface, but by increasing the treatment time, the contents of the carboxylic and carbonyl groups increased to a saturated level after $1{\sim}2$ hour. Before and after the oxidation, the lactone and hydroxyl groups were nearly absent. These results showed that the reaction mechanism of carbon black and ozone is similar to that of ethylene and ozone. Weight of oxidized carbon black was increased after treating AIBN, while free radical was slightly decreased by ESR analysis. When carbon black was treated with organic compounds containing mercapto- groups, the results of ESR showed that free radical peak intensity was almost diminished compared to original carbon black.

• Journal of Aquaculture
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• v.16 no.4
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• pp.257-261
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• 2003

The effects of different stocking densities on the growth of juvenile abalone, Haliotis discus hannai and water quality in the recirculating system with rotating biological contactor, were assessed. The trials were conducted using total weight 32 g juveniles abalone for 60 days at stocking densities of 5, 10, 15 kg/$m^2$. The animals were fed sufficient amounts of the pellet diet of 30.4% protein during the experimental period. Daily feeding rate (DFR) and survival rate (SR) of 5 kg/$m^2$ showed 0.76% and 85.5% those were not significantly differed 10 kg/$m^2$ showing 0.75% and 96.0% (P>0.05). DFR and SR of 15 kg/$m^2$ showing 0.38% and 31.2% were significantly lower than 5 and 10 kg/m2 (P<0.05). Daily growth rate (DGR) and feed efficiency (FE) showed the highest as 0.19% and 24.2% in 5 kg/$m^2$ the lowest as 0.05% and 14.3% in 15 kg/$m^2$ (P<0.05). According to, these results was an inverse relationship between growth and stocking density. The optimum density of juvenile abalone from this experiment is 5 to 10 kg/$m^2$ in the recirculating system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.2
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• pp.177-183
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• 2008

This study aimed to investigate the protective effect of dandelion water extract (DWE) on liver injury induced by D-galactosamine (GalN) in Sprague-Dawley rats. Fifty rats were divided into 5 groups; normal control (C), DWE-control (DWE-C: saline injection after feeding 3% DWE diet), GalN-control (GalN-C: GalN injection after normal diet), DWE I (GalN injection after feeding 1.5% DWE diet), and DWE II (GalN injection after feeding 3% DWE diet). After 2 weeks, the acute hepatitis was induced by GalN (650 mg/kg, i.p.) and 24 hrs later, all rats were sacrificed. The DWE supplement ameliorated the serum alanine and aspartate aminotransferase (AST, ALT) as well as alkaline phosphatase (ALP) and tumor necrosis $factor-{\alpha}\;(TNF-{\alpha})$. Hepatic antioxidative enzyme activities, such as catalase, GSH peroxidase, GSH reductase, and Mn-superoxide dismutase (SOD) were slightly or significantly elevated by the treatment of DWE. Moreover, the histological examination corresponded with these biochemical observations. According to these findings, dandelion could be used as a potential therapeutic material for treating chemically induced acute hepatitis.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.718-724
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• 2018

In this study, the $Ni_{0.9}Co_{0.05}Ti_{0.05}(OH)_2$ precursor was prepared by the concentration gradient co-precipitation method. In order to overcome the structural change due to oxygen desorption in the cathode active material with high nickel content, the physical and electrochemical analysis of the cathode active material according to the calcination temperature were investigated. Physical properties of $Li_{1.05}Ni_{0.9}Co_{0.05}Ti_{0.05}O_2$ were analyzed by FE-SEM, XRD and TGA. The electrochemical performance of the coin cell using a cathode active material and $LiPF_6$(EC:EMC=1:2 vol%) electrolyte was evaluated by the initial charge/discharge efficiency, cycle retention, and rate capabilities. As a result, the initial capacity and initial efficiency of cathode materials were excellent with 244.5~247.9 mAh/g and 84.2~85.8% at the calcination temperature range of $750{\sim}760^{\circ}C$. Also, the capacity retention exhibited high stability of 97.8~99.1% after 50cycles.