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        검색결과 2,503

        1781.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To provide an aqueous rust inhibitor for metalworking lubricant having low toxicity and excellent rust resistance, we synthesized diester of malonic acid by three consecutive esterifications with over 98% of conversion. This substituted malonic diester could be used as an additive to mineral oil based metalworking lubricant. These metalworking lubricant compositions were showed excellent rust resistance and suitable for various metals and different metalworking processes including hot rolling and cold rolling of aluminum and aluminum alloys.
        4,000원
        1782.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It is desirable to have an accurate expression on the temperature dependence of surface(or interfacial) tension Σ, because most of the interfacial thermodynamic functions can be derived from it. There have been proposed several equations on the temperature dependence of the surface tension, Σ(T). Among them Eotvos equation and the one modified by Katayama, which is called Katayama equation, for improving accuracies of Eotvos equation close to critical points, have been most well-known. In this article Katayama equation is interpreted on the basis of the cell model to understand the nature of the equation. The cell model results in an expression very similar to Katayama equation. This implies that, although Eotvos and Katayama equations were obtained on the basis of experimental results, they have a sound theoretical background. The Katayama equation is also modified with the phase volume replaced with a critical scaling expression. The modified Katayama equation becomes a power-law equation with the exponent slightly different from the value obtained by critical-scaling theory. This implies that Katayama equation can be replaced by a critical-scaling equation which is proven to be accurate.
        4,000원
        1783.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Because of the difference in the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenol such as monosubstituted hydroquinone was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid and phenylhydroquinone by the reaction using diphenyl chlorophosphate in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and the addition time of hydroquinone, and by modifying it through an association of hydroquinone with LiCl.
        4,000원
        1784.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Acrylic adhesives for automobiles protection were prepared by emulsion polymerization. Monomers used were n-butyl acrylate(BA), acrylonitrile (AN), butyl methacrylate(BMA), glycidyl methacrylate(GMA), and acrylic acid (AA). Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at 70℃ and agitation speed was kept at 200 rpm. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, when each 0.03 mole of GMA and AA was introduced, the adhesion properties and various above mentioned resistances of the prepared adhesives were satisfied the standard for automobiles.
        4,000원
        1785.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The conductances of trimethyltetradecylammonium bromide (TTAB) plus triphenyltetradecyl phosphonium bromide (TTPB) and TTAB plus trimethylhexadecylammonium bromide (HTAB) over the entire mole fraction range of TTAB were measured in water and in cyclodextrin plus water mixtures at fixed 4 and 8 mM of cyclodextrin at 30℃. The conductivity plot for both binary mixtures shows a single break from which the mixed critical micelle concentration and degree of micelle ionization were computed. From the slope of the conductivity curve, the equivalent ionic conductivities of the monomeric, associated, and the micelle states were calculated and discussed with respect to the surfactant-cyclodextrin complexation in the whole mole fraction range of both surfactant binary mixtures. The association constant K between the respective monomeric surfactant and cyclodextrin cavity of fixed 4 mM cyclodextrin was computed by considering 1:1 association from the surface tension measurement. A comparison among the K values for HTAB-cyclodetrin, TTAB-cyclodextrin, and TTPB-cyclodextrin shows that the former complexation is significantly stronger in comparison to the other ones due to the longer hydrophobic tail.
        4,000원
        1786.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The photocatalytic degradation of methylene blue(MB) was investigated using TiO2 as photocatalyst and UV radiation. TiO2 supported with activated carbon(AC) was prepared by SOL-GEL method and depended on several parameters such as the mass ratio of TiO2/AC, pH and experimental time. The presence of the anatase and rutile crystal phase was determined by XRD analyses of the prepared TiO2. The degradation of MB with TiO2/AC was about 20% higher than that of AC alone. A variation of photodegradation was negligible under UV radiation conditions ( ≥ 40W). It was experimentally showed that the photodegradation rate was increased with increasing the amount of photocatalyst. The optimal catalyst was prepared by impregmation of 5wt%-TiO2 with AC and was calcined at 300℃, and showed about 99% removal efficiency for 3hrs.
        4,000원
        1787.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The accidents occurred by unstable material which is easily exploded or burnt up were caused by heat and collision under the condition of relatively low temperature without oxygen, have been reported frequently. However, the amount of the unstable material is getting higher by development of fine ceramic research area even though its dangerous characteristic is disregarded. This research studied a heat stability and measured boiling point of various carpet material. Carpet has been used in home as well as general indoor usage. Now a day, carpet material which is hardly burnt has been on commercial, but its detailed unstable conditions is not mentioned. This research reports the measurement of the initial temperature of generation heat and heat-radiation change on differential scanning calorimeter (DSC). The DSC data of nylon bulked continuous filament (N-BCF) yam 100%, nylon (NY), poly propylene (PP), and a new material named polytrimethylene terephthalate (PTT) are studied and researched about the effect of them using TGA, furnace, and direct-burning experiment.
        4,000원
        1788.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the electrochemical properties for Langmuir-Blodgett (LB) films mixed with fatty acid (8A5H) and phospholipid (DLPE, DMPC, and DPPA). LB films of 8A5H monolayer and 8A5H-phospholipid mixture were deposited using the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured using cyclic voltammetry with three-electrode system, an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode at various concentrations(0.1, 0.5, and 1.0 mol/L) of NaClO4 solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate was 50, 100, 150 and 200 mV/s, respectively. As a result, LB films of fatty acid and phospholipid (8A5H/DLPE and DPPA) appeared irreversible process were caused by only the reduction current from the cyclic voltammogram and LB film of 8A5H-DMPC mixture was found to be caused by a reversible oxidation-reduction process.
        4,000원
        1789.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Theoretical total nitrogen removal efficiency and reactor volume ratio in oxic-anoxic-oxic system can be found by influent water quality in this study. The influent water quality items for calculation were ammonia, nitrite, nitrate, alkalinity, and COD which can affect nitrification and denitrification reaction. Total nitrogen removal efficiency depends on influent allocation ratio. The total nitrogen removal follows the equation of 1/(1+b). Optimal reactor volume ratio for maximum TN removal efficiency was expressed by those influent water quality and nitrification/denitrification rate constants. It was possible to expect optimal reactor volume ratio by the calculation with the standard deviation of ±14.2.
        4,000원
        1790.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Benzoxazolo carbocyanine compounds were synthesized by condensation of a suitable ortho-ester with an appropriately substituted 2-methylbenzoxazole in the presence of triethylamine. This compounds used as green sensitizing dyes in photographic emulsions. The compounds are characterized by fast atom bombardment mass spectrometry. The values(m/z) of structurally significant ions observed in FAB spectra. It was showed tentative fragmentation pattern in FAB spectroscopy of HN(C2H5)3 cations in glycerol/trifluoroacetic acid matrix.
        4,000원
        1791.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        From the result of pharmacetical characteristics and analysis of Green-tea extract, it could obtain some conclusions as follows. The extract experiment of Green-tea appeared about 10%-extraction ratio as semi-solid state, and after dried in freezing from Green-tea extract of semi-solid state, it obtained about 65% Green-tea extract as solid state. In the results on antimicrobial experiment of Green-tea extract, number of S-typhimurium and fungus in microbe decreased more and more according to the time passage. This phenomenon could show that Green-tea extract keeps antimicrobial effect. In the results on antioxidation experiment of Green-tea extract, DPPH scavenging activity of free radical showed that Green-tea extract appears more remarkable reduction ability than reference samples. This phenomenon means that antioxidation of Green-tea extract appears higher than Vitamin-C and BHA sample. In the results on intrument analysis, the fatty and aromatic components of aniline, acetaldehyde, acetic acid, trichloroethylene, caffeine etcs from Green-tea extract was detected with GC/MS analysis and inorganic components of Ca, Mg, Cu, Mo, Sb, Ti etcs from Green-tea extract was detected with ICP/OES analysis.
        4,000원
        1792.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The high-solid coatings were prepared by blending the synthesized acrylic resin in the previous paper, and hexamethylene diisocyanate-trimer and curing it at room temperature. The characterization of the films of the prepared coatings was performed. The 60˚ specular gloss, impact resistance, cross-hatch adhesion, and heat resistance of the films proved to be good, and the pencil hardness, drying time, and pot-life proved to be slightly poor. From a viscoelastic measurement using a rigid-body pendulum, curing was accelerated with the Tg value.
        4,000원
        1793.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to obtain the maximum flame retardancy as well as the minimum deterioration of physical properties of PU flame-retardant coatings, chlorine and phosphorus functional groups were introduced into the pre-polymer of modified polyesters. In the first step, the tetramethylene bis(orthophosphate) (TBOP) and neohexanediol dichloroacetate (DCA-adduct) intermediates were synthesized. In the second step, 1,4-butanediol and adipic acid monomers were polymerized with the two kinds of intermediates to obtain copolymers. The modified polyesters containing chlorine and phosphorus (ATBA-10C, -20C, and -30C) were synthesized by adjusting that the content of phosphorus compound was fixed as 2wt% and the contents of chlorine compound (dichloroacetic acid) were varied as 10, 20, and 30wt%. Average molecular weight and polydispersity index of the preparation of ATBAs were decreased with increasing DCA content because of the increase in hydroxyl group that retards reaction.
        4,200원
        1794.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, magenta coupler was prepared by the reaction of 1-(2,4,6-Trichlorophenyl)-3-(5-amino-2-chloroanilino)-5-pyrazolone with 2,4-di-tert-pentyl-phenoxy butanoyl chloride in the presence of pyridine. The product was identified by using various analytical tools such as melting point, elemental analyzer, IR spectrophotometer, UV-Vis spectrophotometer and GC-mass spectrometer. The reaction of magenta coupler with CD-3 (color development agent) was shown magenta color.
        4,000원
        1795.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Acrylic resins (HSCs : EA/EMA/2-HEMA/CLA) which contain 80% solid content were synthesized by the copolymerization of monomers (ethyl acrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate) and functional monomer (caprolactone acrylate : CLA) which improves the crosslinking density and physical properties of films. The physical properties of the prepared acrylic resins (HSCs) containing CLA, are as follows: viscosity 1440~2630 cps ; Mn 1590~1660 ; and conversions, 81~86%, respectively. From the correlation of Tg values, viscosities, and Mn of the HSCs, it was found thst viscosity and Mn increased with Tg value.
        4,000원
        1796.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Modified polyesters (TTBA-10C, -20C, -30C) that contain phosphorus and chlorine were synthesized by the condensation polymerization of tetramethylene bis(orthophosphate), neohexanediol trichlorobenzoate, 1,4-butanediol and adipic acid, in which tetramethylene bis(orthophosphate) and neohexanediol trichlorobenzoate were prepared previously in our laboratory. In this study, two-component flame-retardant polyurethane coatings (TTBA-10C/HDI-trimer=TTHD-10C, TTBA-20C/ HDI-trimer= TTHD-20C, TTBA-30C/HDI-trimer= TTHD-30C) were obtained by curing at room temperature with the synthesized TTBAs and hexamethylene diisocyanate (HDI)-trimer as a curing agent. The obtained TTHDs were made into coating samples and used as test samples for various physical properties. The physical properties of the flame-retardant coatings containing chlorine and phosphorus groups were generally inferior to those containing only phosphorus group. Flame retardancy was tested by vertical and horizontal combustion method, and 45˚ Meckel burner method. Since the retardancy of flame-retardant coatings containing chlorine and phosphorus groups was better than that containing only phosphorus group, it could be concluded that the retardancy by the synergism effect of chlorine and phosphorus groups exhibited.
        4,000원
        1797.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The influence of fluorophor, scatterer, absorber in turbid materials by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it is studied the molecular property by laser induced fluorescence spectroscopy. It can be found that the effects of optical property are penentrated in scattering media by the optical parameters(μs, μa, μt, γ, σ). The value of scattering coefficient μs is large appeared by means of the increasing particles of scattering, it can be found that the slope appears exponentially as a function of distance from laser source to detector. It may also utilize in designing the best model for oil chemistry, laser medicine and application of medical engineering.
        4,000원
        1798.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methanol and formaldehyde were produced directly by the partial oxidation of methane. The catalysts used were mixed oxides of late-transition metals, such as Mn, Fe, Co, Ni and Cu. The reaction was carried out at 450℃, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by XRD, TPD and BET apparatus. Of the catalysts, A-Mn0.2-6, which contains 0.2 mole of Mn and calcined at 600℃, showed the best catalytic activity: 3.7% methane conversion, and 30 and 28% methanol and formaldehyde selectivities, respectively. The catalytic activity was changed with the content of Mn and the calcination temperature. Catalytic activity increased with the specific surface areas of the catalysts. With XRD, it was found that the structure of the catalysts are changed with calcination temperature. Through O2-TPD experiment, it was found that the catalysts showing good catalytic activity showed O2 desorption peak around 800℃.
        4,000원
        1799.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Kelvin equation is revisited, which accounts for important phenomena observed frequently in nano-dispersion systems. They include vapor pressure increase for curved interfaces, nucleation, capillary condensation, Ostwald ripening and so on. The smaller the radius of curvature is, the more significant Kelvin equation becomes. Therefore, its meaning, curvature effect, and importance are examined and discussed.
        4,000원
        1800.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we prepared porous cation exchange membrane using polystyrene such as, EPS (expanded polystyrene), SAN (styrene acrylonitrile copolymer) and HIPS (high impactive polystyrene). These polystyrenes were sulfonated by acetyl sulfate to make porous cation exchange membrane such as, SEPS, SSAN, SHIPS. SEM was employed to confirm porous structure of membrane, and IR spectroscopy was used to confirm sulfonation rate of ion exchange membrane. Water and methanol content were also increased with amount of sulfuric acid in reactants. SSAN-20 showed the highest value in water and methanol content. Fixed ion concentration and conductivity was also increased with an amount of sulfuric acid in reactants. Methanol permeability for SEPS-20, SSAN-20, SHIPS-20 was found to be 1.326 × 10-5 cm2/s, 1.527 × 10-5 cm2/s and 1.096 × 10-5 cm2/s respectively. From the result of electrodialysis experiment in 0.03 M Pb(NO3)2 aqueous solution, anion exclusion and cation selection effects were confirmed.
        4,000원