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        검색결과 2,636

        2081.
        2003.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Environmental friendly acrylics/urea high-solid paints (BEHCU) were prepared through the curing reaction of acrylics resin(BEHC) containing 70wt% of solids content and butylated urea curing agent. BEHC was synthesized by addition copolymerization of caprolactone acrylate(CLA), 2-hydroxypropyl methacrylate(2-HPMA), ethyl methacrylate, and n-butyl acrylate. The addition polymerization of these monomers, especially including flexible CLA monomer and 2-HPMA monomer with OH funtional group, under appropriate reaction conditions resulted in polymers with controlled glass transition temperature(Tg) and crosslinking density. The molecular weight(Mw) of these polymers(BEHCs) was 2940~3240 and polydispersity (Mw/Mn) was in the range of 1.61~1.72. The viscosity and the molecular weight of these acrylic resins increased with increasing Tg. The coated films were prepared using curing reaction between BEHC resin and butylated urea curing agent at 100℃ for 30 minutes. Our experimental resulted showed that enhancement of the coating properties such as adhesion, flexibility, impact resistance, water resistance, and abrasion resistance could be expected through introducing CLA component in acrylic resin for the high-solid content acrylics/urea coatings.
        4,300원
        2082.
        2003.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prepare a softener, alkyl imidazoline salt, fatty carbamide salt, and fatty polyamide salt were synthesized first, and then the synthesized salts were blended. The prepared softeners were applied to acrylic fibers, and then several properties were tested. As a result, the prepared softeners show good softening and lubricating properties, and they also show a little antistatic property. Through bending resistance tests and measurements of feeling change of acrylic fibers treated with the softeners, it was proved that the prepared softeners are durable softeners.
        4,000원
        2083.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Self-diffusion coefficients of colloidal ass9Ciation structures in the aqueous solutions of anionic ammonium dodecyl sulfate (ADS) and cationic octadecyltrimethylammonium chloride (OTAC) surfactants were measured by pulsed-gradient spin echo NMR. The results were interpreted on the basis of the ADS/OTAC/water phase diagram. Crossing the phase boundaries, significant changes in self diffusion coefficients were observed and well correlated to the phase diagram. For the micelles their apparent radii were obtained from Stokes-Einstein equation. Their values were 15 for the ADS micelles and 54 a for the OTAC micelles, respectively. For vesicles which were formed spontaneously at different relative amounts of the surfactants and total surfactant concentrations, the radius was measured as 50 to 200 nm. This result is in fair agreement with those by TEM and light scattering.
        4,000원
        2084.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A new process for polymeric gate insulator in field-effect transistors was proposed. Fourier transform infrared absorption spectra were measured in order to identify ODPA-ODA polyimide. Its breakdown field and electrical conductivity were measured. All-organic thin-film transistors with a stacked-inverted top-contact structure were fabricated to demonstrate that thermally evaporated polyimide films could be used as a gate insulator. As a result, the transistor performances with evaporated polyimide was similar with spin-coated polyimide. It seems that the mass-productive in-situ solution-free processes for all-organic thin-film transistors are possible by using the proposed method without vacuum breaking.
        3,000원
        2085.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Transesterfication of vegetable oils and methanol with alkaline catalyst was carried out to produce biodiesel fuel by continuous process. The process consists of two static mixers, one tubular reactor and two coolers and gave 96~99% of methyl ester yield from soybean oil and rapeseed oil. Experimental variables were the molar ratios of methanol to vegetable oil, alkaline catalyst contents, flow rates, mixer element number. The optimum ranges of operating variables were as follows; reaction temperature of 70℃, l:6 of molar ratio of methanol to oil, O.4%(w/w) sodium hydroxide based on oil, static mixer elements number of 24 and 4 min. residence time.
        4,000원
        2086.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Natto, one of Japanese traditional food is made from steamed whole soybeans fermented with Bacillus natto. In this study, the effects of Natto mucilage- feeding on griwth, organ weight and serum nitrogen compounds of rats were investigated. Male rats in Sprague-Dawley strain were fed on basal diets supplemented with aqueous Natto mucilage of several percentages for 10 weeks. Natto mucilage had no significant effects on the body and organ weights. The levels of GOT, GPT, LDH. and total bilirubin in serum of rats fed Natto mucilage diets were significantly lower than those in the control group ' The levels of total protein and albumin were higher than those in the control group. The level of calcium in serum indicates a growing tendency. but creatinine, uric acid, and BUN had declining. And the most component of free am1no acids in Natto mucilage were glutamin acid.
        4,000원
        2087.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Environmental friendly acrylic/urea high-solid paint(MUHC) were prepared through the curing reaction of acrylics resin(EBHC) containing 70wt% of solids content and butylated urea curing agent. The synthesis of EBHC Was done at 150℃ for 6 hours, and the results were obtained as follows : Mn=1830~2190, Mw 3290~4000, Mw/Mn=1.80~1.83 viscosity=110~352 cps, and conversion=82~92%. After the film was coated with MUHC, the various physical properties were measured. They showed that enhancement of the coating properties such as adhesion, flexibility, abrasion resistance, impact resistance, and water resistance could be expected through introdl1cing caprolactone acrylate component in acrylics resin for the high-solids content acrylics/urea coatings.
        4,000원
        2088.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Demand for organic analysis increase as industries are growing and many products are spreaded in the daily life. One of many products is oil spill dispersant. It was used for oil accident in the ocean. When oil spill dispersant spread at the ocean, the petroleum in the ocean is dispersed. The oil spill dispersant is made of non ionic surfactant and petroleum oil. The non ionic surfactant disperse petroleum from oil accident. The other part is petroleum oil which has aromatic hydrocarbon. Because the aromatic hydrocarbon is cancerogenic material, it directly injure animals in the ocean. This cause the second pollution in the human body. Many oil accidents still are controlled by oil spill dispersant. Therefore quality control of the oil spill dispersant become important and this also demand for the exact quantitative analysis of aromatic hydrocarbon. Hereupon the first we develop separate petroleum oil from surfactant. The second standardize analytical method of aromatic hydrocarbon in the separated petroleum oil.
        4,000원
        2089.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the effect of electron injection layer on the performance of organic light emitting devices (OLEDs). As an electron injection layer, the quinolate metal complexes were used. We optimized the device efficiency by varying the thickness of the quinolate metal complexes layer. The device with 1 nm of the quinolate metal complexes layer showed significant enhancement of the device performance and device lifetime. We also compared the effect of 8-hydroxyquinolinolatolithium (Liq) with that of bis(8-quinolinolato)-zinc (Znq2) and 8-hydroxyquinolinolatosodium (Naq) as an electron injection layer. As a result, Liq is considered as a better materials for the electron injection layer than Znq2 and Naq.
        4,000원
        2090.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fatty polyamide that gives softness, lubrication and bulky property and alkyl imidazoline that gives durable softness and antistatic property were synthesized. then, an O/W-type durable softener (DSN) was prepared by the emulsion of the synthesized fatty polyamide and alkyl imidazoline. Emulsion stability of the DSN was good, and the mixed HLB value was 11.2. From the measurement of softness, lubrication, antistatic property, bending resistance, and color fastness, it was proved that the prepared DSN was a good durable softener for nylon.
        4,000원
        2091.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dermorphin is a hepta peptide(H-Tyr-DAla-Phe-Gly-Tyr-Pro-Ser-NH2)with exceptionally potent and long-lasting peripheral and central activity. Dermorphin analogues, dermorphionyl(DMP)-Lys-NH2 and DMP-Lys-Lys-NH2 have been prepared in order to examine the effect of opiod activity. Dermorphin analogues were synthesized by the solid phase method. The crude peptide was purified by gel filter on a Sephadex LH-20, characterized with HPLC and amino acid analyzer. Analgesic potency was estimated by writhing syndrome method and Randall-Selitto method. As a result, dermorphin analogues have lower potency than that of morphine.
        4,000원
        2092.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Thermal decomposition of the copolymer of butyl methacylate(BMA) with styrene(St) was investigated. The copolymer Was obtained at 80 ℃ in a continuous stirred tank reactor(CSTR) using toluene and benzoyl peroxide(BPO), as solvent and initiator, respectively. The reactor volume was 0.3 liters and residence time was 3 hours. The thermal decomposition followed the second order kinetics for BMA/St copolymer. The activation energies of thermal decompositon were in the ranges of 38 ~43 kcal/mol for BMA with St copolymer and a good additivity rule was observed with the composition of copolymer. The thermogravimetric trace curve agreed well with the theoretical calculation.
        4,000원
        2093.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        CaCO3 absorbed sodium lauryl sulfate (SLS) surfactant was prepared, Core-shell polymers of inorganic/organic pair, which have both core and shell component, were synthesized by sequential emulsion polymerization using styrene(St) as a shell monomer and potasium persulfate (KPS) as an initiator, We found that when CaCO3; core prepared by adding 2,0 wt% SLS, CaCO3 core/PSt shell polymerization was carried out on the surface of CaCO3 particle without forming the new PSt particle during St shell polymerization in the inorganic/organic core-shell polymer preparation, The structure of core-shell polymer were investigated by measuring the degree of decomposition of CaCO3 using HCl solution, thermal decomposition of polymer composite using thermogravimetric analyzer and morphology by scanning electron microscope.
        4,000원
        2094.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pyrolysis of polypropylene(PP) Was performed to find the effects of the pyrolysis temperature(425, 450, 475 and 500℃) and the pyrolysis time(35, 50 and 65minutes), respectively. Conversion and liquid yield obtained during PP pyrolysis continuously increased with the pyrolysis temperature( up to 500℃) and the pyrolysis time(up to 65minutes), especially these were more sensitive to the pyrolysis time at 425℃ than other pyrolysis temperatures. Each liquid product formed during the pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The liquid products of PP pyrolysis up to 450℃ were almost same fractions(26±3wt.% gasoline, 20±2wt.% kerosene and 23±2wt.% light oil) except wax(3~13wt.%). On the other hand, the pyrolysis of PP from 475℃ to 500℃ produced 26±3wt.% wax, 24±1wt.% gasoline, 18±1wt.% kerosene and 16±1wt.% light oil. After all, the main liquid product changed from gasoline to wax with increasing pyrolysis temperature.
        4,000원
        2095.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Liquid-phase methanol synthesis via methyl formate using coal-derived syngas was carried out in a bench-scale(diameter 173 mm and dispersion height 1200 mm) slurry bubble column reactor(SBCR) Under the condition of 180˚. 61 atm, 30 L/min, H2/CO=2 and a slurry mixture of 2 kg of copper chromite and 0.5 kg of KOCH3 suspended in 14 L of methanol, the per pass conversions of syngas is 6 %, maximum concentration of methyl formate 3.088 mol% and maximum synthesis, rate of methanol 0.8 gmole/kg · hr. It is a significant evidence that copper chromite powder as heterogeneous catalyst didn't active for the hydrogenolysis of methyl formate to methanol, resulting copper chromite powder was not efficiently suspended in a slurry mixture. To enhance the hydrogenolysis of methyl formate in liquid-phase methanol synthesis process, the designed SBCR have need to use the higher specific gravity solvent and/or decrease the catalyst particle size.
        4,000원
        2096.
        2002.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A (disk-like liquid crystal (DLC) monomer/liquid crystals(LCs)/chiral dopant/dichroic dye) composite was irradiated with ultraviolet (UV) light. The (DLC network/LCs/chiral dopant/dichroic dye) was formed in the homeotropically oriented smectic A(SA) phase by the surface orientation treatment and the electric field. A focal-conic texture exhibiting strong light scattering appeared in the heat-induced chiral nematic phase(N*) of the composite upon heating. Thermo-recording in the composite system has been realized by using a He-Ne laser. The laser irradiation was induced the phase transitions from SA phase to chiral nematic(N*) phase in the composite system.
        4,000원
        2097.
        2002.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A mixture of methyl ester derivatives of fatty acids from the oils of pine nuts was well resolved to five fractions differing by degree of unsaturation by silver ion solid-phase extraction column chromatography (Ag+-SEC). Polyunsaturated fatty acid with non-methylene interrupted conjugated double bond (NMiDB) radical held more strongly to silver ions in the column than methylene interrupted conjugated double bond (MiDB) one when they had the same number of double bonds. Although both the picolinyl ester and DMOX derivative provided clear mass ion species powerful enough to elucidate the structure of the polyunsaturated fatty acid (PUFA) with NMiDB and/or methylene interrupted conjugated double bond (MiDB) radical in the oils, the picolinyl ester of PUFA with NMiDB radical did not provide a cluster of mass ions neighboring diagnostic mass ions induced by the double bond in the proximal to the carboxyl group. However, the DMOX derivative of PUFA with NMiDB group as well as MiDB showed abundant mass ion species differing by gaps of 12 amu, which made it possible with greater ease to locate the double bonds in the molecule. The oil contained C18:2Ω6 (46.2 %) and C18:1Ω9 (25.4 %) as main components, and considerable amounts of PUFAs with NMiDB radical such as δ5. 9. 12-C18:3 (16.0 %), δ5. 9-C18:2 (2.3 %) and δ5. 11. 14-C20:3 (0.8 %).
        6,000원
        2098.
        2002.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated carbons with high surface area of 2,600 m2/g and high pore volume of 1.2 cc/g could be prepared by KOH activation of rice hulls at a KOH:char ratio of 4:1 and 850℃. In order to increase the adsorption capacity of hydrogen sulfide, which is one of the major malodorous component in the waste water treatment process, various contents of Na2CO3 and KIO3 were impregnated to the rice-hull activated carbon. The impregnated activated carbon with 5 wt.% of Na2CO3 showed improved H2S adsorption capacity of 75 mg/g which is twice of that for the activated carbon without impregnation and the impregnated activated carbon with 2.4 wt.% of KIO3 showed even higher H2S adsorption capacity of 97 mg/g. The improvement of H2S adsorption capacity by the introduction of those chemicals could be due to the H2S oxidation and chemical reaction with impregnated materials in addition to the physical adsorption of activated carbon.
        4,000원
        2099.
        2002.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The catalytic activities of several metalloporphyrin, wherein the porphyrins are TPP(5,lO,l5,20-Tetraphenyl-21H,23H-porphyrin) and (p-X)TPP (X =CH3O, CH3, F, Cl), are reported for the oxidation of styrene and it's derivatives. The electronic effects of substrates and porphyrins on the catalytic activity of metalloporphyrin containing the transition metal ion such as Mn(III) was discussed. Investigating the correlation between the Michaelis-Menten's rate parameters and the substituent constants, we are going to analyze the influences on the changes of catalytic activity or rate determining step during the processes of the formation and the dissociation of the M-oxo-olefin.
        4,000원
        2100.
        2002.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Isothermal pyrolysis of high density polyethylene(HDPE), polypropylene(PP) and polystyrene(PS) was performed at 450℃, respectively. The effect of pyrolysis time on yield and product composition was investigated. Conversion and liquid yield obtained during HDPE pyrolysis continuously increased with time up to 80minutes, but those of PP and PS did not largely change after 35minutes. Each liquid product formed during the pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The major liquid product of HDPE pyrolysis was light oiH34 wt.% based on the amount of HDPE treated) and the amounts of the other liquid ingredients(gasoline, kerosene and wax) were almost the same. On the other hand, the pyrolysis of PP produced 27 wt.% gasoline, 22 wt.% kerosene, 24 wt.% light oil and 13wt.% wax, and the pyrolysis of PS produced 56 wt.% gasoline, 12 wt.% kerosene, 9 wt.% light oil and 13 wt.% wax.
        4,000원