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        검색결과 289

        141.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Copper alloy metal fiber was incorporated into the conventional water-soluble metal working fluids to increase the antimicrobial activity. Fluid treated by copper alloy metal fiber is shown that bacteria is disappeared whereas that untreated metal fiber is increased bacteria as increasing the life time. When the electrochemical potential of Cu/Zn ion is -268mV, radicals with molecular oxygen are easily made. Especially, hydroperoxide radical shows strong toxicity to the strains, leading to the conformational change of plasma membrane. As a result antimicrobial activity of copper alloy metal fiber in metal working fluid is superior to that of copper fiber.
        4,000원
        142.
        2008.10 구독 인증기관·개인회원 무료
        In soil ecosystems, chemicals are often found as mixtures. Therefore, the toxicity data generated by single toxicity tests are inadequate for assessing the potential risk of complex mixtures of chemicals for soil ecosystems. In the present study, the mixture toxicity of copper and manganese on the reproduction of Paronychiurus kimi were assessed using a Toxic Unit approach (1TU=EC50). The concentrations of each metal in the mixture were summed as follows: TUmixture = CCu/EC50 of Cu + CMn/EC50 of Mn, where CMetal are the concentrations of copper and manganese in the mixture. From the Sum TU based dose-response relationships, sum of a toxicunit (TU50) at 50% reduction for the mixture (EC50mix) was calculated. The binary mixture toxicity was defined as being concentration additiv (EC50mix=1TU) or as being more or less than additive (EC50mix<1TU or 1>TU, respectively). Also, values of the mixture (TUi) at i% reduction found were predicted to get more insight regarding the relationship between mixture toxicity and various effect levels (ranging from EC10 to EC90). The toxicities of copper and manganese mixtures were less than additive at the EC10 level, whereas more than additive at the EC90 level. These findings imply that the effect levels are important for determining the toxicity of metal mixtures.
        143.
        2008.10 구독 인증기관·개인회원 무료
        In order to establish a year round indoor-rearing system for Copper butterflies; large copper butterfly, Lycaena dispar, the effect of temperature on larval development and diapause was investigated. Temperature has been suggested as an important factor regulating the developmental rate, length of life, and survival rate from insect. As temperature increased, the developmental period was gradually shorten. The developmental periods of large copper larvae had a range of 11.0 days to 28.5 days at 30℃ and 17.5℃ respectively. The highest emergence rate was 94.2% recorded at 20℃. And the low emergence rate was 72.7% under 17.5℃. We investgated the sensitive stages to diapause induction in the larger copper effect of temperature and photoperiod. The experiment involves transfer of individuals from diapause averting (LD 16:8h, 25℃) to diapause inducing condition (LD 8:16h, 20℃) at various stages. Diapause was induced in 95.2% insect transferred at hatching larvae, in 15.6% of insects transferred at 2nd stadium molt, in 0% of insects transferred at after 3rd stadium molt. Percentage diapause induction increase with the length of short days and low temperature experienced. The main stage sensitive to photoperiod and temperature induction of diapause determination is the early first larval instar. The diapause induction began 14 days and ended 20 days after hatching larvae (LD 8:16h, 20℃).
        144.
        2008.06 구독 인증기관 무료, 개인회원 유료
        The acute and subacute toxicities of copper sulfate were evaluated in zebrafish (Brachydanio rerio). Dipping of fishes for acute toxicity was performed for a period of 24 h, and TLm24h value (median tolerance limit = LC50) was 1.36 ppm. Clubbing of gill filaments due to severe epithelial hyperplasia of gill lamella were oberved. And epithelial edema, fusion and necrosis of renal tubules were presented. The most significant change was mild epithelial hyperplasia of gill lamella in subacute toxicity test which fishes were exposed to 0.15 ppm of copper sulfate for 1 week.
        4,000원
        145.
        2008.06 구독 인증기관 무료, 개인회원 유료
        The Cheongju Wonheung Ecological Park was constructed to help the multiplication of toads, following the beginning of the development of surrounding areas. A great number of CCA (Chromated Copper Arsenate)- treated wood structures were included in the construction around the pond and the migration passage to the nearby mountain (Guryong Mountain). Noticeable malformation, however, occurred in toad tadpoles and most of them were found to be dead after all. This study was conducted to find the cause of the incidence, focusing on the contamination of the area with heavy metals. CCA-treated wood, soil, and water samples were collected around the pond and they were analyzed for heavy metals. The results showed that teratogenic copper concentrations were highly elevated in pond water and soil samples, suggesting that CCA-treated wood may be a potential source of toad malformation.
        4,000원
        146.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The oxygen and nitrogen enriched activated carbons were obtained from modification of commercial activated carbon by using nitric acid, sodium hydroxide and urea. Zeta-potentials of modified activated carbons were investigated in relation to copper ion adsorption. The structural properties of modified activated carbons were not so much changed, but the zeta-potentials and isoelectric points were considerably changed. The zeta-potential of nitric acid modified activated carbon was the most negative than other activated carbons in the entire pH region, and the pHIEP was shifted from pH 4.8 to 2.6, resulted in the largest copper ion adsorption capacities compare with other activated carbons in the range of pH 3~6.5. In case of urea modified activated carbon, copper ion adsorption was larger than that of the as-received activated carbon from pH 2 to pH 6.5 even though the pHIEP was shifted to pH 6.0, it was due to the coordination process operated between nitrogen functional groups and copper ion. The adsorption capacity of copper ion was much influenced by zeta-potential and pHIEP of carbon adsorbent.
        4,000원
        147.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon contamination from the binder resin is an inherent problem with the metal powder injection molding process. Residual carbon in the W-Cu compacts has a strong impact on the thermal and electric properties. In this study, uncertainty was quantified to evaluate determination of carbon in a W-15%Cu MIM body by the combustition method. For a valid generalization about this evaluation, uncertainty scheme applied even to the repeatability as well as the uncertainty sources of each analyse step and quality appraisal sources. As a result, the concentration of carbon in the W-Cu part were measured as 0.062% with expanded uncertainty of 0.003% at 95% level. This evaluation example may be useful to uncertainty evaluation for other MIM products.
        4,000원
        150.
        2007.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study is focused on the possibility of copper alloy metal fiber for an antimicrobial activity in the water soluble metal working fluids. Electrochemical potential of Cu/Zn ion is -268mV, and easily makes radicals with molecular oxygen. Especially, hydroperoxide radical shows strong toxicity to the strains. Plasma membrane causes conformational change when hydroperoxide radical binds to plasma membrane. Elution of copper ion from copper alloy metal fiber is detected in metal working fluid. As a result antimicrobial activity of copper alloy metal fiber in metal working fluid is superior to that of copper fiber.
        4,000원
        154.
        2007.02 구독 인증기관 무료, 개인회원 유료
        Oxidation characteristics of benzene as a VOC was investigated using a fixed bed reactor system over copper base catalysts. The copper base catalysts were made by using copper nitrate reagent and various support materials such as γ-Al2O3, TiO2, and zeolite. The parametric tests were conducted at the reaction temperature range of 200~500℃, benzene concentration of 1,000~2,000 ppm, and space velocity range of 5,000~20,000 hr-1. The property analyses such as BET, SEM, XRD and the conversions of catalytic oxidation of VOC were examined. XRD analysis on copper catalysts showed CuO crystal forms and the peak intensity of CuO increased as the impregnation weight of copper grew. The experimental results showed that the conversion was increased with decreasing space velocity. It was also found that Cu/γ-Al2O3+TiO2 catalyst showed the highest activity for the oxidation of benzene and 15% metal loading was the optimum impregnation level.
        4,800원
        158.
        2006.09 구독 인증기관·개인회원 무료
        We developed the copper core ball electroplated with Sn-Ag-Cu of the eutectic composition which used mostly as Pb free solder ball with high reliability. In order to search for the practicality of this developed copper core ball, the evaluation was executed by measuring the initial joint strength of the sample mounted on the substrate and reflowed and by measuring the joint strength of the sample after the high temperature leaving test and the constant temperature and the humidity leaving test. This evaluation was compered with those of the usual other copper core balls electroplated with (Sn,Sn-Ag,Sn-Cu,Sn-Bi) and the Sn-Ag-Cu solder ball.
        159.
        2006.09 구독 인증기관·개인회원 무료
        We studied formation of nanostructured -Cu composites under shock wave conditions. We investigated the influence of preliminary mechanical activation (MA) of Ti-B-Cu powder mixtures on the peculiarities of the reaction between Ti and B under shock wave. In the MA-ed mixture the reaction proceeded completely while in the non-activated mixture the reagents remained along with the product . titanium diboride. The size of titanium diboride particles in the central part of the compact was 100-300 nm.