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        검색결과 2,503

        1481.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon nanotube(CNT) plays an essential role in various fields of nano based science and technology. Recently, silica coated CNT composites are interested because they are useful for the optical, magnetical, and catalytic applications. In this report, carboxyl groups were introduced on the MWCNT using nitric acid. In order to maximize the silica encapsulation efficiency, carboxyl groups of MWCNT reacted with a silane coupling agent were used to prepare silica coated MWCNT. Due to their strong interaction between modified MWCNT and TEOS. Silica layer with a controllable thickness was achieved. Silica coated MWCNT were further utilized as the template for the synthesis of hollow silica nanotubes after 800℃ calcination.
        4,200원
        1482.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The analysis of reaction kinetics provided that the reaction order was the 1st of triglyceride and the rate constant was 0.067 min-1. The transesterification of camelina oil using 0.6 wt% mixed catalyst which consists of 40 v/v% of potassium hydroxide (1 wt%) and 60 v/v% of tetra methyl ammonium hydroxide (0.8 wt%), was carried out at 65℃ on the tubular reactor packed with static mixer. The conversion was shown to be 95.5% at the 6:1 molar ratio of methanol to oil, flow rate of feed of 3.0 mL/min and 24 of element of static mixer. The volume of washing water emitted by 0.6 wt% mixed catalyst was the half of the volume emitted by 1 wt% potassium hydroxide.
        4,000원
        1483.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Transdermal drug delivery(TDS) offers many important advantages. For instance, it is easy and painless, it protects the active compound from gastric enzymes, and it avoids the hepatic first-pass effect. Also, it is simple to terminate the therapy if any adverse or undesired effect occurs. But skin is a natural barrier, and only a few drugs can penetrate the skin easily and in sufficient quantities to be effective. Therefore, in recent years, numerous studies have been conducted in the area of penetration enhancement. The most commonly used transdermal system is the skin patch using various types of technologies. Compared with other method of dosage, it is possible to use for a long term. It is also possible to stop the drug dosage are stopped if the drug dosage lead to side effect. Polysaccharide, such as xanthan gum and algin were selected as base materials of TDS. Also, these polymers were characterized in terms of enhancers and drug contents. Among these polysaccharide, the permeation rate of Paroxetine such as lipophilic drug was the fastest in xanthan gum matrix in vitro. We used glycerin, PEG400 and PEG800 as enhancers. Since dermis has more water content(hydration) than the stratum corneum, skin permeation rate at steady state was highly influenced when PEG400 was more effective for lipophilic drug. Proper selection of the polymeric materials which resemble and enhance properties of the delivering drug was found to be important in controlling the skin permeation rate.
        4,000원
        1484.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To develope new natural substances for whitening agent, Baeckji(Angelica dahuria;BK), Seasin(Asarum sieboldii;SS). Baecjgangjam(Bombycis corpus;BGJ) and Mynkanbang(MKB) were selected and extracted by hot water and 70% EtOH, respectively. Hydrothermal and ethanolic extracts of BK, SS, BGJ and MKB were evaluated for anti-oxidative effect, tyrosinase activity, melanogenesis of B16 melanoma cells and changes in level of tyrosinase expression by using Western blotting. All hydrothermal and ethanolic extracts showed scavenging activities of free radicals against 1,1-diphenyl-2-picrylhydrazyl(DPPH) but no inhibitory effect on tyrosinase activity. Ethanolic extracts of BK, SS, and BGJ and especially highly, those of MKB inhibited production of melanin in B16 melanoma cells and were able to reduce the level of tyrosinase expression in B16 melanoma cells. These results suggest that ethanolic extracts of BK, SS, BGJ and MKB can be an effective whitening agent from natural plant.
        4,000원
        1485.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The author previously reported that the addition of inuloprebiotics to broiler diets produces growth performance that is superior to antibiotic supplementation. The present study furthered this work by evaluating the quality with thiobarbituric acid reactive substances (TBARS) of the meat from chickens fed inuloprebiotics produced using Korean Jerusalem artichoke. Male Ross 308 broilers (n=240) were randomly allotted to a 35 day regimen of dietary control (no supplementation), dietary antibiotics supplementation (8 mg avilamycin/kg diet), or dietary inuloprebiotic supplementation (450 mg inuloprebiotics/kg diet). The pH, water holding capacity, L*value (lightness), and b*value (yellowness) of the chicken meat weres ignificantly higher in the inuloprebiotic group. The TBARS value of chicken meat stored at low temperature tended to increase according to the length of storage, and was significantly lower in the inuloprebiotics group. The sensory scores of the cooked chicken meat were significantly higher in the inuloprebiotics group. The results indicate that the addition of inuloprebiotics as anantimicrobial agent to broiler diets can greatly improve the quality and self-life with reducing TBARS of chicken meat.
        4,000원
        1486.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, by using oleic acid and polypropylene glycol, good natured antifoaming agent for suitable electronics process under the alkaline conditions were synthesized. For the synthesized mono and diesters, acid value, hydroxyl value was measured, and identified by FT-IR and 1H-NMR spectroscopy. Surface properties such as surface tension, critical micelle concentration(cmc) for diluted aqueous solution was measured, and tested the antifoaming properties according to the difference of alkyl chain length, various concentration, temperature and pH. The surface tension of synthesized antifoaming agent, PPMO(Polypropylene glycol monooleate) was 24.3 dyne/cm, PPDO(Polypropylene glycol dioleate) was 23.7 dyne/cm. By increasing of the alkyl chain length, surface tension was decreased slightly, and showed good antifoaming properties at 0.06 wt% concentration and 50℃, pH 11. These synthesized compounds are expected to apply as a suitable antifoaming agents in the semiconductor and the PCB(Printed Circuit Board) manufacturing process.
        4,000원
        1487.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cationic gemini-surfactant, namely 1,4-butane-bis(N-alkanoyloxyethyl-N,Ndimethyl)-diammonium bromide was synthesized and their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. The synthesized product was confirmed by FT-IR and 1H-NMR spectroscopy. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was 4.1×10-5~5.4×10-5 mol/L. The Krafft point of the these surfactants were 〈0~10.7℃. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, 1,4-butane-bis(N-lauroyloxyethyl-N,N-dimethyl)- diammonium bromide, CGL 14-4-14 has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.
        4,000원
        1488.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to make high-purity ferro-manganese from Mn3O4 waste dust, the application of aluminothermite process to the reduction of the waste dust was investigated. The mixture from Mn3O4 dust as metallic source and Al metal powder as the reductant ignited, and reduced with an extremely intense exothermic reaction. The rapid propagation of the aluminothermite reaction occurred spontaneously and stably by ignition of the mixture. The Manganese having some alloy elements emerged as liquids due to the high temperatures reached up to about 2,500℃ and separated from the liquid by their differences of specific gravity. The result of thermite reaction showed the fact that can be obtained high purity ferro-manganese which have over about 90% of manganese content and lower impurities such as C, P, S than those of KS D3712 specification. The recovery of manganese from Mn3O4 dust was lower level of about 65% than about 75% from manganese ore by electric furnace process, that is due to spatter loss because of its extremely intense thermite reaction. But it will be improved by the process designed to provide CaO as the cooler or to use the Al metal powder having larger particle size distribution.
        4,000원
        1489.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        New type of 5-fluorobenzimidazole derivatives was synthesized through the reaction of 4-fluoro-5-(2,6-dimethylmorpholinyl)-2-aminoaniline with 5-nitro-2-furoic acid and 5-methoxy-3-chlorobenzothiophene-2-carboxylic acid in presence of PPA and treatment of OH-. the resulting substituted 5-fluorobenzimidazole derivatives(6), (7) was characterized by high solubility in common polar organic solvents. We considered 5-fluorobenzimidazole derivatives were useful especially for antifungal drugs. These results are discussed from the viewpoints of the chemical and physical structures of the 5-fluorobenzimidazole derivatives.
        4,000원
        1490.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we experimented that how influence chain extension to waterborne urethane-epoxy hybrid resin for leather garment coatings. First of all, We had analyzed datas by FT-IR, SEM and machanical properties. By instruments analysis measurement we confirmed that synthesis of epoxy and hybrid resin. In this experiment we knew that polyurethane-epoxy hybrid resin have 5 grades of solvent resistance. Tensile strength measured in the polyurethane-epoxy resin(EDA 5.37g, 2.386 kgf/mm2) had the most strong strength.. Also polyurethane-epoxy hybrid resin had better result(EDA 5.37g. 37.4 mg. loss) than other hybrid resins. As hight proportion of EDA in hybid resin, we obtained low elongation and low flexibility. In this result, chain extension of waterborne polyurethane-epoxy hybrid resin showed that how effect in leather coating by ratio of EDA.
        4,000원
        1491.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study of wave propagation and scattering in biological media has become increasingly important in recent years. The propagation of light within tissues is an important problem that confronts the dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. In the clinical application of photodynamic therapy(PDT) and in photobiology, the photon deposition within a tissue determines the spatial distribution of photochemical reactions. Scattered light is measured as a function of the distance (r) between the axis of the incident beam and the detection spot. Consequently, knowledge of the photosensitizer(Chlorophyll-a) function that characterizes a phantom is measured. To obtain the results of scattering coefficients(μs) of a turbid material from diffusion described by experimental approach. It was measured the energy fluency of photon radiation at the position of penetration depth. From fluorescence experimental method obtained the analytical expression for the scattered light as the values of (I/Io)wavelength vs the distance between the center of the incident beam and optical fiber in terms of the condition of "in situ spectroscopy(optically thick)" and real time by fluorometric measurements. The result was compromised with transport of intensities though a random distribution of scatters.
        4,000원
        1492.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We estimated on the stability of W/O type emulsified fuel using by capacitance sensor, so it concluded the following conclusions. For the first 24 hours, prepared emulsified fuel reveals phase separation ratio of 5%, maintains stable status which verifies the stability of emulsified fuel. Adding more water increases the phase separation ratio rapidly, and adding more surfactant displays stable emulsification. Adding water causes larger size of water droplet diameter, and adding surfactant mixture causes smaller size of water droplet diameter. In conclusion, the size of W/O type emulsified fuel water droplet diameter is directly related to the volume of surfactant, and density of water droplet diameter changes thedistribution according to water contents.
        4,000원
        1493.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Expanded graphites were used as anode materials of high power Li-ion secondary battery. The expanded graphite was prepared by mixing the graphite with HClO4 as a intercalation agents and KMnO4 as a oxidizing agents. The physical and electrochemical properties of prepared expanded graphites through the variation of process variables such as contents of intercalation agent and oxidizing agent, and heat treatment temperature were analyzed for determination of optimal conditions as the anode of high power Li-ion secondary battery. After examing the electrochemical properties of expanded graphites at the different preparing conditions, the optimal conditions of expanded graphite were selected as 8 wt.% of oxidizing agent, 400 g of intercalation agent for 20 g of natural graphite, and heat treatment at 1000℃. The sample showed the improved charge/discharge characteristics such as 432 mAh/g of initial reversible capacity, 88% of discharge rate capability at 10 C-rate, and 24 mAh/g of charge capacity at 10 C-rate. However, the expanded graphite had the problems of potential plateaus like natural graphite and lower initial efficiency than the natural graphite.
        4,000원
        1494.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Atopic dermatitis is a chronic inflammatory skin disease associated with cutaneous hyper-reactivity to environmental triggers. In order to develop effective therapeutic herbal extracts for atopic dermatitis, cytotoxicity, antioxidant, anti-inflammatory and anti-allergic activities were investigated for various herbal extracts. Among candidate extracts, we selected Aloe vera L. (AV), Viola mandshurica W. Becker (VM), Punica granatum L. (PG), Dendrobium nobile L. (DN) and mixture of the above extracts (MX) for further investigations. All of them did not show cytotoxic activities to macrophage RAW264.7 cells below the concentration of 100 ppm. All showed antioxidant, anti-inflammatory and anti-allergic effects, although to various extents. In antioxidant effects, AV showed the highest effect, followed by PG and VM, while DN did the lowest. In evaluation for anti-inflammatory activities in macrophage RAW264.7 cells, AV and DN inhibited almost completely the LPS-induced production of nitric oxide, while AV, DN and VM showed strong inhibitory activities on the LPS-induced production of TNF-α. In anti-allergy effect in mast cell HMC-1, DN showed the highest effect, followed by AV and PG, while VM did the lowest. In the topical allergy reaction induced by compound 48/80 in Sprague-Dawley rat, DN exhibited significant anti-allergic effect, while PG, VM and AV did slight effect. These results suggest that AV, VM, PG and DN have antioxidant, anti-inflammatory and anti-allergic activities, and thus have the potential to reduce and alleviate the symptoms of atopic dermatitis.
        4,000원
        1495.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of study was to investigate polluted amounts 16 PAHs in railroad(waste railway ties) area, factory area and land-fill area. All of the samples were analyzed by GC-MSD(SIM mode), and the recovery range, detection limit and standard deviation obtained by this experiment were 73.88 ~ 94.75%, 0.009 ~ 2.252 μg/kg and 1.861 ~ 12.373, respectively. The concentrations of total PAHs(t-PAHs) and total carcinogenic PAHs(t-PAHcarc) in soils of three area were in the range of 12.54 ~ 3274.95 μg/kg on a wet weight basis with a mean value of 499.8 μg/kg and 0 ~122.77 μg/kg with a mean value of 20.16 μg/kg, respectively. The correlation between t-PAHs and t-PAHcarc appeared very high in railroad(waste railway ties) area (R2 = 0.8301), factory area (R2 = 0.9217) except land-fill area(R2 = 0.3782), indicated that t-PAHcarc concentration increases in proportion with t-PAHs.
        4,200원
        1496.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Polymer electrolyte membrane fuel cell (PEMFC) performance degrades when hydrogen sulfide (H2S) is present in the fuel hydrogen gas; this is referred to as H2S poisoning. This paper reveals H2S poisoning on PEMFC by measuring electrical performance of single cell FC under various operating conditions. The severity of H2S poisoning depended on H2S concentration under best operating conditions(65℃ of cell temperature and 100% of anode humidification). H2S adsorption occured on the surface of catalyst layer on MEA, but not on the gas diffusion layer(GDL) by analyzing SEM/EDX data. In addition, MEA poisoning by H2S was cumulative but reversible. After poisoning for less than 150 min, performance of PEMFC was recovered up to 80% by just inert nitrogen gas purging.
        4,000원
        1497.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated the C-V diagrams and metal surface related to the electrochemistry characterization of metal(nickel, SUS-304). We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system. A measuring range was reduced from initial potential to -1350mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate were 50, 100, 150, 200 and 250 mV/s. As a result, the C-V characterization of metal using N,N-dimethylacetamide and N,N-dimethylformamide inhibitors appeared irreversible process caused by the oxidation current from the cyclic voltammogram. After adding organic corrosion inhibitors, adsorption film constituted, and the passive phenomena happened. According to the results by cyclic voltammetry method, it was revealed that the addition of inhibitors containing amide functional group enhances the corrosion resistance properties.
        4,000원
        1498.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For the synthesis of water soluble acrylic modified epoxyester resin, fatty acid/epoxy ratio of 50/50 was used, and introduced maleic anhydride. Ratio of styrene/acrylic acid of acrylic monomers was fixed 85/15 and ratio of epoxyester/acrylic monomer was controlled 80/20, 75/25, 70/30, 65/35, and degree of neutralization were changed 65%, 80%, to 100%. As a result, 40% solids acrylic modified epoxyester resins were synthesized. Resins were evaluated water soluble stability, drying time, water resistant, storage stability and physical properties. And the white paints were prepared, and were evaluated viscosity, drying time, water resistance, adhesion, sagging, spray workability, gloss, salt spray resistance, skinning, whiteness and flash rust. As a result, the degree of neutralization of 100% and the ratio of epoxyester/acrylic monomer of 75/25 showed the best properties.
        4,500원
        1499.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The sterilization of strain and algae in sea water was studied to see the possibility to apply the redox reaction of metal alloy to meet the international marine organization(IMO) regulation, which was to regulate deballasting concentration of strain and algae above 99% of sterilization. Two different kinds of brass were heat treated at different temperature and cooled rapidly to conserve the specific character of β brass. Untreated Muntz metal showed the best result of antimicrobial rate in sea water, and 7:3 brass showed similar result to Muntz metal. Heavy metal elution rate was inversely proportional to the sterilization capability.
        4,000원
        1500.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Esterification reaction between succinic acid[SA] and 1,4-butanediol [BD] was kinetically investigated in the presence of organometallic catalysts (ESCAT-100Ag18, MBTO) at 150~180℃. The reaction followed from the measurement of the quantity of water which was distilled from the reaction vessel. The esterification reaction was carried out under the first order kinetics with respect to the concentration of reactants and catalyst, respectively. The overall reaction order was 2nd. From the examination of relationship between apparent reaction rate constants and reciprocal absolute temperature, the activation energy has been calculated as 146.70 kJ/mol(ESCAT-100Ag18) and 87.57 kJ/mol(MBTO), respectively.
        4,000원