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        검색결과 2,503

        1761.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper describes the experiments for investigating the effects of thermal stability of several commercial carpet mate materials. The melting point and thermal decomposition temperature was measured by means of a differential scanning calorimeter(DSC) in air condition. The DSC data and burning test results of nylon bulked continuous filament(N-BCF) yarn 100%, nylon(NY), polypropylene(PP), and a new material named polytrimethyleneterephthalate(PTT) were analysed to obtain the effect on their thermal stability. Conclusively, we observed that PTT and PP were approximately 380℃ and 240℃ to start the thermal decomposition, respectively. In other words, PTT is thermally the most stable material for carpet manufacturing.
        4,000원
        1762.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        [1,2,4]-Triazole derivatives were synthesized by 5 steps. Benzimidazole was refluxed with ethyl chloroacetate to give 1H-benzimidazole-acetic acid ethyl ester (1) over 52% yield. Ester (1) was refluxed with hydrazine hydrate in the presence of ethanol to afford 1H-benzimidazole-1-acetic acid, hydrazide (2). 5-Benzoimidazol-1-ylmethyl-4H-[1,2,4]triazole-3-thiol (4) was made via coupling of compound (2) with methyl isothiocyanate, followed by cyclization of 1H-benzimidazole-1-acetic acid, 2-[(methylamino) thioxomethyl]hydrazide (3) on reflux, and finally the target compounds (6a-6v) were synthesized by general substitution reaction. Compounds (6a-6v) were screened for T-type calcium channel blocker using the fluorescence assay by FDSS6000. All compounds (6a-6v) did not show better activities than control compound, mibefradil.
        4,000원
        1763.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Generally, it has been known that positive plate efficiency is the most influential effect on the initial current capacity of lead acid battery. Thus, in this study, we have investigated the curing effect of the positive plate, which is one of the important lead acid battery processes. The curing process of the positive plate is performed either with the separation of each plate with 1mm gap or with no gap of plate. As a result, when there is no interval between each plate, the higher temperature current happened than expected, resulting in the changes in the initial current efficiency of the lead acid battery. The chemical composition and crystal structure of a material coated on the positive plate were identified with XRD and SEM. It was resulted that were only there not a lot of 4BS (tetrabasic-lead sulfate, 4PbO·PbSO4) on the plate in case of curing of plates without interval, but a large quantity of Pb3O4 also formed on the surface. On the other hand, it was observed that 3BS (tribasic-lead sulface, 3PbO·PbSO4·H2O) was the main product on the plate in case of typical curing process with some interval. From the initial current capacity test, the positive plate having 3BS was approximately 40% higher in initial current capacity than that having 4BS. It was concluded that 4BS and Pb3O4 on the plate surface were harmful to the initial current capacity of lead acid battery.
        4,000원
        1764.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The influences of fluorescence, scattering, and flocculation in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by the spectroscopy of laser induced fluorescence (LIF). The effects of optical properties in scattering media have been found by the optical parameters(μs, μa, μt). Flocculation is an important step in many solid-liquid separation processes and is widely used. When two particles approach each other, interactions of several colloid particles can come into play which may have major effect on the flocculation and LIF process, The value of scattering coefficient μs is large by means of the increasing particles of scatterer it has been found that the slope decays exponentially as a function of distance from laser source to detector. It may also aid in designing the best model for oil chemistry, biopharmaceutical products, laser medicine and application of medical engineering on LIF and coagulation in particle transport mode.
        4,000원
        1765.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The PU flame-retardant coatings (TTBAH, ATBAH-10C, -20C, and -30C) were prepared using the synthesized ATBAs and HDI-trimer as curing agent at room temperature. The physical properties of PU flame-retardant coatings with chlorine and phosphorus were inferior to those with phosphorus only and the properties were getting worse with increasing chlorine content. Flame retardancy was tested with three methods. With the vertical method, complete combustion time of ATBAHs were 259~347 seconds, which means that the prepared coatings are good flame-retardant. With the 45˚ Meckel burner method, char lengths of the three prepared coatings were less than 2.9 cm, which indicates that the prepared coatings are first grade. With the limiting oxygen index (LOI) method, the LOI values of the three prepared coatings were in the range of 30~35%, which proves good flame retardancy of the prepared coatings. from the result of flame retardancy tests of the specimens that contain the same amounts of flame retarding compounds. it was found that the coatings containing both phosphorus and chlorine show higher flame retardancy than the coatings containing only phosphorus. This indicates that there exists, some synergy effect between coexisting phosphorus and chlorine.
        4,300원
        1766.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prepare high-solid coatings, first acrylic resins (HSAs) which contain 80% solid were synthesized, and then the prepared resins were cured with isocyanate at room temperature. In the synthesis of HSAs, viscosity, number average molecular weight (Mn) and conversion were 1372~2700 cps, 1520~1650 and 83~87%, respectively. Among the four kinds of initiators used, tert-amylperoxy-2-ethyl hexanoate was the most proper one in the synthesis of HSAs. With increasing Tg values, viscosity increased rapidly and molecular weight increased slowly. As a result of the examination of coated films, it was found that 60˚ specular gloss, impact resistance, heat resistance and cross-hatch adhesion were good, and pencil hardness, drying time and pot life were poor.
        4,000원
        1767.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The pyrolysis of high density polyethylene(HDPE) and low density polyethylene(LDPE) was carried out at temperature between 425 and 500℃ from 35 to 80 minutes. The liquid products formed during pyrolysis were classified into gasoline, kerosene, gas oil and wax according to the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The conversion and yield of liquid products for HDPE pyrolysis increased continuously according to pyrolysis temperature and pyrolysis time. The influence of pyrolysis temperature was more severe than pyrolysis time for the conversion of HDPE. For example, the liquid products of HDPE pyrolysis at 450℃ for 65 minutes were ca. 30wt.% gas oil, 15wt.% wax, 14wt.% kerosene and 11wt.% gasoline. The increase of pyrolysis temperature up to 500℃ showed the increase of wax product and the decrease of kerosene. The conversion and yield of liquid products for LDPE pyrolysis continuously increased according to pyrolysis temperature and pyrolysis time, similar to HDPE pyrolysis. The liquid products of LDPE pyrolysis at 450℃ for 65 minutes were ca. 27wt.% gas oil, 18wt.% wax, 16wt.% kerosene and 13wt.% gasoline.
        4,300원
        1768.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The esterification of palmitic acid in rapeseed oil and methanol emulsified by propylene glycol with PTSA(p-toluene sulfonic acid) was followed by the transesterification of rapeseed oil into biodiesel with 1(w/v)% GMS(glycerol monostearate) as an emulsifier using TMAH(tetramethyl ammonium hydroxide) catalysts at 60℃. The former reaction was optimized at the 1:20 of molar ratio of oil to methanol and 5wt% PTSA, and the latter was optimized at the 1:8 of molar ratio of oil to methanol and 0.8wt% TMAH. The overall conversion into biodiesel was 98% after 60min of reaction time at the 1:8 of molar ratio, 0.8wt% TMAH and 60℃. TMAH was a good catalyst to control the viscosity of biodiesel mixture.
        4,000원
        1769.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This article investigated to polymer-clay nanocomposite, especially in interfacial respect clay structure, its dispersion into polymer matrix, and clay modification is studied. The cationic exchange of surfactants with clay gallery results in preparing organo-clay capable of compatiblizing to monomer or polymer and increasing interlayer adhesion energy due to expansion of interlayer spacing. The orientation of surfactant in clay gallery is affected by chemical structure and charge density of clay, and interlayer spacing and volume is increased with alkyl chain length of surfactant, or charge density of clay. Also, the interaction between clay and polymer in preparing polymer-clay nanocomposite is explained thermodynamically. In the future, the study and development of polymer-clay nanocomposite is paid attention to the interfacial adhesion, clay dispersion within polymer, mechanism of clay intercalation or exfoliation.
        4,000원
        1770.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Multilayer adsorptions and BET adsorption are analyzed statistical-mechanically. Which ensemble is selected for the analysis is unimportant, because each ensemble yields the same results. However, the amount of mathematical manipulations and the matter of convenience vary from ensemble to ensemble. Hence, multilayer adsorptions and BET adsorption are examined using a canonical and a grand canonical ensembles, and an ensemble of subsystems. Also, the characteristics of multilayer and BET adsorptions are delineated.
        4,000원
        1771.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Water quality has been deteriorated by the increasing amount of industrial waste water that is due to the better standard of living. In order to lessen the polluted water and substantially reutilize it at factories, a new method is needed. The plasma generator, which uses discharge current below 1,500 voltage and processes at extremely low temperature, has more strong oxidization than current method and an advantage of miniaturizing the apparatus in dealing with waster water by producing carrier gas at room temperature. This study were measured on the 3 kinds of waster water to the plasma generator for 120 minutes. As results, COD was almost decreased and removed in 15 minutes. The results suggest that the plasma generator can be used reduce COD and removal of color for various waster water, which can be reutilized as industrial water, It would be of benefit to the country like Korea in which qualified water is deficient.
        4,000원
        1772.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PU type flame-retardant coatings (TBAO/L-75, TBAOL ; TBAO/N-100, TBAON) were prepared by blending bromine-containing modified polyester (TBAO) which was synthesized in our earlier work. with two kinds of isocyanate curing agents, Desmodur L-75 and Desmodur N-100. Physical properties of the prepared flame-retardant coatings were tested. TBAOL shows better hardness than TBAON, while TBAON shows better viscosity, accelerated weathering resistance, yellowness index and lightness index difference than TBAOL. There were no remarkable differences in fineness of grind, 60˚ specular gloss, cross-hatch adhesion, and abrasion resistance of TBAOL and TBAON. There was no discernable difference in flame-retardancy between the two flame-retardant coatings, TBAOL and TBAON. When the content of tribromo acetic acid, which is flame-retarding component, was 30wt% the LOI value was in a range of 29~30%, which indicates that the two coatings are good flame-retardant coatings.
        4,000원
        1773.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It is attempted to develop flame retardant polyurethane coatings, which have received significant attention in recent years. It is the purpose of this study to synthesize new reactive polyurethane coatings containing halogen. Lactone based modified polyester polyols, using trichlorobenzoic acid as chlorine moiety (TBAOs) were synthesized. These polyesters were cured with isophorone diisocyanate (IPDI)-isocyanurate at room temperature (TBAPUs). Physical properties of these flame retardant coatings were similar with those of non-flame retardant coatings. The flammability of coatings was strongly dependent on the chlorine contents. We found that the increasing chlorine contents showed better flame retarding properties and that, however, they also resulted in more smog generation during combustion. The detailed results of flammability test using various methods indicated 24~26% in LOI and 3.7~5.3 cm char length in 45˚ Meckel burner method.
        4,300원
        1774.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Field emission display(FED) is actively investigated in view of the development of full color flat-panel display, which can replace some cathode-ray tube(CRT). Thus, the development of new phosphors appropriate for FED is urgently needed and has been actively investigated. In this work, SrTiO3:Pr3+ phosphor was prepared by sol-gel method and the coating was applied by sol-gel method combined with sonication on these phosphor's surface into diluted precursor solution. It was found that very fine particles of coating material were formed on phosphor's surface. The luminescent intensity of SrTiO3:Pr3+ phosphor coated with SiO2 and Al2O3 was considerably increased without any noticeable change in color chromaticity. The optimum concentration of coating material was found to be 1wt% and the optimum pH value of the solution was 10.
        4,000원
        1775.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Polyimide is a well-known organic dielectric material, which has not only high chemical and thermal stability but also good electrical insulating and mechanical properties. In this research, the electric conduction mechanism of PI Ultra-Thin Films was investigated at room temperature. At low electric field, ohmic conduction (I∝V) was observed and the calculated electrical conductivity was about 4.23×10-15~9.81×10-15 S/cm. At high electric field, nonohmic conduction (I∝V2) was observed and the conduction mechanism was explained by space charge limited region effect. The dielectric constant of PI Ultra-Thin Films was about 7.0.
        4,000원
        1776.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Anti-corrosive coatings for steel structures with an alternative anti-corrosive pigment, polyaniline was prepared and anti-corrosive characteristics of the prepared coatings were investigated. The structure of the polyaniline was identified by using FT-IR, UV/Vis. and TGA analysis, and the anti-corrosive properties were analyzed from the results of the salt spray experiment. We found that the anti-corrosion properties of the prepared coatings varied in accordance with the types of primer coating resins as well as with the existence and nonexistence of the top coating. In this condition, the properties of adhesion, chemical resistance, and water resistance were found to be very satisfactory when using the single-packaged urethane resin as the primer coating resin and the urethane resin as the top coating resin.
        4,000원
        1777.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methanol and formaldehyde were produced directly by the partial oxidation of methane over mixed oxide catalysts. The catalysts were composed of Mo and Bi with late-transition metals, such as Mn, Fe, and Co. The reaction was carried out at 450℃, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by O2-TPD and BET apparatus. Among the catalysts used, the catalyst composed of 1:1:2.5 molar ratio of Mo:Bi:Mn showed the best methane conversion and methanol selectivity. The change in ratio of methane to oxygen affected at the conversion and selectivity, and the most proper ratio was 10:1.5. Methane conversion, methanol and formaldehyde selectivities increased with the surface areas of the catalysts. From the O2-TPD result, it was found that the oxygen species responsible for this reaction might be the lattice oxygen species desorbed at high temperature around 800℃.
        4,000원
        1778.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        From experiment results on pharmacetical characteristics and analysis of Glycyrrhizin extract, some conclusions are obtained as follows. From results on extract experiment of Glycyrrhizin, it appeared about 8%-extraction ratio as semi-solid state, and after dried in freezing from Glycyrrhizin extract of semi-solid state, it obtained about 70%-Glycyrrhizin extract as solid state of yellow gold color. From results on antimicrobial experiment of Glycyrrhizin extract, number of S-typhimurium and Fungus in microbe decreased more and more according to time passage. This phenomenon shows that Glycyrrhizin extract keeps antimicrobial effect. From results on antioxidation experiment of Glycyrrhizin extract, DPPH scavenging activity of free radical shows that Glycyrrhizin extract appears more remarkable reduction ability than reference samples. This phenomenon means that antioxidation of Glycyrrhizin extract appears higher than Vitamin-C and BHA. From results on instrument analysis, the fatty and aromatic components of 2-pentanone, cyclohexasiloxane, tetrasiloxane, benzoquinoline-2-carboxylic acid etcs from Glycyrrhizin extract was detected with GC/MS and inorganic components of Ca, Mg, Ti, Zn, Fe etcs from Glycyrrhizin extract was detected with ICP/OES.
        4,000원
        1779.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Y2-xGdxO3:Eu, phosphors for plasma display panel(PDP), were prepared by Pechini method which use yttriun chloride, gadolinium chloride, and europium oxide as starting materials. This method is a different way to the synthesis of europium(Eu)-doped phosphors, and it consists of the formation of a polymeric resin obtained by polyesterification between metal chelate compounds and a polyfunctional alcohol. This needs lower temperature than solid-state synthetic method. The prepared Y2-xGdxO3:Eu phosphor particles had spherical shape and coherence. The luminescence intensity of Y2-xGdxO3:Eu phosphor particles increased according to the increase of gadolinium(Gd) content(to 0.8mol%), and Y1.2Gd0.8O3:Eu phosphors had the highest luminescence intensity under vacuum ultra violet(VUV) excitation. The optimum concentration of Eu in the phosphor and optimum calcination temperature was 3wt% and 1100℃. The prepared phosphors were consist of particle, and its size was between 100nm and 150nm. Among the different polyfunctional alcohols, diethylene glycol(DEG) improved the luminescence intensities of phosphors more than other additives. The Pechini method proved that it is demonstrated to be suitable for the synthesis of phosphors used in PDP.
        4,000원
        1780.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Direct decomposition of methane over three types of carbon black (N330-p, N330-f, and HI-900L) was carried out in a fluidized bed quartz reactor. Properties of carbon black before and after reaction were measured and found to be related with surface structure and weight gain. For N330-p and N330-f, some carbon deposit on the surface was considered to be the reason for the increase of BET surface area and pore volume with weight gain. Carbon deposits on the surface and the conglutination of some aggregates may explain the slight increase of particle size. Properties of HI-900L changed much more significantly with weight gain. It is supposed that the increase of aggregate size of HI-900L were due to some unknown oily components. The corresponding agglomeration might be the reason for the decrease of BET surface area with weight gain, as compared with the increase of that for the case of N330 black.
        4,000원