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        검색결과 2,636

        1801.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Two component polyurethane (PU) flame retardant coatings were prepared by blending trichloro modified polyesters (TCMPs) and isophorone diisocyanate isocyanurate. TCMPs were synthesized by polycondensation of trichlorobenzoic acid (TCBA), a flame retardant component, with adipic acid, 1,4 butanediol, and trimethylolpropane. The content of TCBA was varied in 10, 20, and 30 wt% for the reaction. Theses new flame retardant coatings showed various properties comparable to other non flame retardant coatings. Moreover, we carried out the combustion test and the flammability test for our flame retardant coatings. The results of vertical burning test for the coatings containing more than 20 wt% of TCBA were determined as no burn. The results of flammability test for the coatings with 20 wt% and 30 wt% of TCBA contents indicated the limiting oxygen index (LOI) values of 26% and 29% respectively, which implied relatively good flame retardancy.
        4,000원
        1802.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to synthesize high-solid coatings, acrylic resins (HSAs) containing 90% solid content were first synthesized, then the synthesized HSAs were cured with a curing agent, isocyanate, at room temperature to obtain high-solid coatings. In the HSAs synthesis, conversion was in a range of 82~87%, and viscosities and number-averaged molecular weight (Mn) of the HSAs were in a range of 4380~8010 cP and 1540~1660, respectively. From the correlation between Tg value, viscosity and Mn, it was found that, with increasing Tg value, viscosity increases rapidly and molecular weight increases slowly. From the visco-elasity measured by the pendulum method, it was found that the curing time decreased with increasing Tg values. From the tests of physical properties of the coatings' film, 60˚ specular gloss, impact resistance and heat resistance were proved to be good and pencil hardness, drying time and pot-life were proved to be poor.
        4,000원
        1803.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        오래전부터, 많은 여성들은 자신들의 젊음을 연장하고, 외모를 더 아름답게 가꾸고, 이를 죽을 때까지 유지하는 것을 바래왔다. 이에 의사와 약사들뿐만 아니라, 많은 화장품 연구자들도 노화와 관련된 기술개발에 총력을 기울여 왔다. 따라서, 이들 연구자들은 노화방지를 위한 새로운 원료를 찾고, 이를 안정화하고, 피부로 전달하는 기술개발에 항상 관심을 쏟아왔다. 뛰어난 노화방지 화장품 개발을 위해서, Ubiquinone의 일종인 ldebenone에 대해 연구하였고, 이를 비수계 피부유사막 기술을 가지고 캡슐화하고 약물전달하는 연구를 진행하였다. 먼저, 편광현미경(PM, Polarized Microscope), X-선 회절분석(XRD, X-ray Diffractions) 및 시차주사열량계 (DSC, Differential Scanning Calorimetry)를 이용하여 Idebenone을 담지한 피부유사막 액정을 비수계 조건에서 구조 및 열적특성을 조사하였다. 그 결과 비수계 조건에서도 규칙적으로 패킹(Packing)된 지질이중층(Lipid bilayer)과 용매의 연속층으로 이루어진 고밀집된 라멜라(Lamella) 구조의 형성유무와 이때의 상거동을 확인할 수 있었다. 결론적으로 높은 극성도로인해 물분자와 접촉하면 불안정해지는 경향이 있는 Idebenone을 비수계 조건에서 각질층(SC, Stratum Corneum)과 구조 및 조성이 유사한 피부유사막을 디자인하여 안정하게 캡슐화 하였다. 이를 적용한 화장품은 모든 보관조건에서 유화입자의 안정성을 유지함을 확인하였고, Idebenone의 활성역가 또한 40℃에서 6개월 동안 약 90%이상을 유지하는 우수한 결과를 나타냈다.
        4,000원
        1804.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The fat of Tra and Basa catfish (Mekong Delta, Viet Nam) was evaluated for the first time as the potential feedstock for biodiesel production, due to its abundance, availability and cheap cost. The unsaturated fatty acid contents of Tra and Basa fat were 57.97% and 64.17%, respectively. Biodiesel was prepared from Tra and Basa fat by methanolysis reaction using alkali catalysts like sodium hydroxide and potassium hydroxide. Effects of various process parameters on biodiesel production, such as molar ratio of methanol to fat, catalyst concentration, temperature and time were investigated. As those results, the transesterification can be performed under moderate conditions, and the biodiesel yields were shown more than 90%. KOH catalyst was the best catalyst for biodiesel production from both Basa and Tra fat. As the feedstock aspect, Basa fat was indicated more efficiency than that of Tra fat. The maximum yield could be achieved by the transesterification from Basa fat with 5:1 molar ratio of methanol to fat, 0.8% KOH catalyst, 50℃, and 50 min. For Tra fat, the optimal condition were at 6:1 molar ratio of methanol to fat, 0.8% KOH catalyst, 50℃, and 45 min. Nowadays, due to cheaper cost and abundance, Tra fat is a promised resource for cheap biodiesel production in Viet Nam.
        4,600원
        1805.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although the pyrimidine derivatives were obtained in low yields ranging from 8% to 20%, we reported the successful preparation of N,N-diaryl-pyrimidin-2-amine derivatives starting from the corresponding 2-aminopyrimidines (1a-1c), by direct palladium-catalyzed arylation using different arylbromides. The reasons of low yields are thought to be the electronic and steric effects by the neighboring aromatic systems. The absorption spectra and photoluminescent spectra of compounds (3a 3g and 4a-4c) were measured using dichloromethane on the concentration of 25 mM by UV vis spectroscopy and luminescent spectroscopy. Pyrimidine derivatives 4a, 4b, and 4c showed moderate emission maxima at 474 nm, 481 nm, and 367 nm, respectively, while other compounds showed very weak photoluminescence or no photoluminescence at all.
        4,000원
        1806.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The malting process of rice (OM4080 variety from Mekong Delta Rice Research Institute) was studied under pilot condition plan by means of the second-order experimental design. Processing parameters, such as the steeping time (0-60 hrs), steeping temperature (5-45℃), germination time (0-8 days), germination temperature (5-45℃) and gibberellin concentration (0-2 mg/kg) were investigated. As a result, all germination conditions, especially germination time, germination temperature, and gibberellin concentration had a significant effect on the malting loss, amylase activity and starch content. The protein content was not clearly affected by any conditions. The optimum conditions for malting process (with highest amylase activity) were as follows: 30 hrs of steeping time, 30-35℃ of steeping temperature, 5-5.5 days of germination time, 25℃ of germination temperature, and 1.5 mg/kg of giberrellin concentration.
        4,000원
        1807.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The esterification of free fatty acid in Jatropha oil added by propylene glycol using p-TSA catalyst was done, and then the transesterification of Jatropha oil added by 1.0vol% GMS as an emulsifier using TMAH, and mixed catalyst(60wt%-TMAH+ 40wt%-KOH) respectively was followed at 60℃. The esterification conversion at the 1:8 molar ratio of free fatty acid to methanol using 8.0wt% p-TSA was 94.7% within 60min. The overall conversion at the 1:8 molar ratio of Jatropha oil to methanol and 60℃ using mixed catalyst was 95.4%. The kinematic viscosity of Biodiesel using TMAH and mixed catalyst in 24h met the ASTM D-6751 above 30℃, and showed a little more than its criterion.
        4,000원
        1808.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Anti-microbiological effects of xanthorrhizol, ie., extract from curcuma xanthorrhiza and extract from houttuynia cordata Thunb. against influenza virus and E. coli O157 were tested. From the influenza experiments, the effects were shown above 93 % in case of houttuynia cordata Thunb. extract, however, the effects was not shown in case of xanthorrhizol. The effects were sustained in mixtures of houttuynia cordata Thunb. and curcuma xanthorrhiza extracts. We also tested the anti-microbiological effects of hand sanitizer containing houttuynia cordata Thunb. and xanthorrhizol. The effect of hand sanitizer containing 2,000 ppm of xanthorrhizol and 500 ppm of houttuynia cordata Thunb. extract was better than that of commercialized foreign product.
        4,000원
        1809.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Among the efforts to increase the efficiency of organic light-emitting device (OLED), there is a way: doping phosphorescent materials. As a phosphorescent material, complexes of heavy transition metal, platinum, were synthesized. Cl- ion and phenyl group were used as ancillary ligands with 2-(2-pyridyl)benzimidazole (pbi) as a chromophore. The complexes were analysed by FAB-mass spectrometer and absorption and emission spectra were obtained. A phenyl group was able to shift the emission band of the complex even if it's not a chromorphore.
        3,000원
        1810.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Adsorption is one of the most efficient method for the separation of low level carbon dioxide. In order to enhance the adsorption capacity, a few additives such as alkali hydroxides were combined with the zeolitic sorbents. As a result of the experimental examination by applying the CO2 flow of 3000 ppm, the composite sorbent showed the improved quality to a certain degree and the added binder was also found to contribute to better adsorption.
        4,000원
        1811.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated phase separation by adding different concentrations of MTBE, to the mixtures of naphtha, ethanol and water. The phase separation temperatures of the Naphtha-Ethanol-Water solutions have dropped when the concentration of MTBE increases more. When adding IPA and IBA to the solutions of Gasoline-Ethanol and Gasoline base-Ethanol individually, IBA shows lower temperatures of phase separation than IPA, and it shows synergistic effect when mixtures of IPA and IBA is applied.
        4,000원
        1812.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The central role of tyrosine phosphorylation in cell proliferative signaling mechanisms provides another target for chemotherapy. The aim of this research is to develop new quinazoline derivatives that possess the inhibitory activity for depidermal growth factor receptor (EGFR) tyrosine kinase (TK) as protein kinase inhibitors. In this work, a series of new 4-anilino-6-guanidino-7-methoxyquinazoline derivatives (12a-l) were synthesized by the introduction of guanidine moiety at C-6 of quinazoline nucleus and evaluated for their EGFR TK inhibitory activities.
        4,300원
        1813.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Separation of naphthalene from naphthalene and 2-methylnaphthalene mixture has been studied by layered melt and solution crystallization using ethylalcohol. Purity and yield of naphthalene depended mainly on the cooling rate: The effective distribution coefficient (Keff) as the degree of impurity removal was observed to decrease with the decreasing in cooling rate. Purity of naphthalene can be enhanced to 5~7% by melt crystallization using 90% naphthalene and the purity of naphthalene can be obtained to be 99% up by solution crystallization.
        4,000원
        1814.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, benzoxazolo carbocyanine is of industrial importance as green-sensitizing dye in the spectral sensitization. Sensitizing dye was prepared by the reaction of 2-methyl-3-sulfopropyl-4,5-benzoxazolium (inner salt) with triethyl orthobenzoate in the presence of triethylamine. The product was identified by using various analytical tools such as elemental analyzer, IR spectrophotometer, UV-Vis spectrophotometer, 1H-NMR spectrometer, TGA and DSC. The maximum absorption peak in methanol solvent was 507 nm. Therefore, it was concluded that benzoxazolo carbocyanine dye can be used as sensitizing dye for the spectral sensitization of photographic emulsion and color cosmetics.
        4,000원
        1815.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to fine antioxidant and whitening agent source from nature, the comparisons of antioxidative activity and tyrosinase inhibitory activity were carried out for various ethanol extract on Pueraria Radix, Poria Cocos, and Coptidis Rhizoma. Comparing for three ethanol extracts, the highest electron donating ability was found at Poria Cocos (81.2%), but, the highest SOD-like ability, at the Coptidis Rhizoma(58%). Xanthine oxidase experiment exhibited 23.3% of hindrance effect in Pueraria Radix, and 79.3% in Poria Cocos. To evaluate at the whitening effect, tyrosinase inhibitory activity was conducted. Tyrosinase inhibitory activity was detected at 17.9% in the Puerariae Radix, 5.2% in the Poria Cocos and 83.3% in the Coptidis Rhizoma. From these results, we suggest that the ethanol extracts from Pueraria Radix, Poria Cocos, and Coptidis Rhizoma can be used for cosmetic ingredients.
        4,000원
        1816.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The performance of positive plates depends on the structure of the lead dioxide active mass. The positive active materials (PAM) consists of a skeleton, built up of agglomerates and macropores. Agglomerates, in their turn, comprise particles and micropores. This paper described a study conducted to determine the effects of different soaking times between the acid fill and formation stages of the tubular plate production. For the positive plates a lead oxide were filled into tubular bag with a red lead. After filling the positive plates were soaked in H2SO4 solution. X-ray diffraction(XRD), scanning electron microscopy(SEM) and electrical testing had been used to study the compositional and morphological aspects of the positive active material(PAM) just prior and after formation. Results indicate that PAM compositions were effected by the soaking time and acid density of H2SO4 solution. It can be seen that as the soaking time duration increases, α-PbO, Pb3O4, and Pb were all gradually sulphating. Composition of 3BS reached a maximum at around 3 h duration and H2SO4 of sp. gr. 1.10 on soaking. This results would suggest that the most beneficial conditions for soaking were the H2SO4 of sp. gr. 1.10 and 2 to 6 h of soaking.
        4,000원
        1817.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The transformation of the liquid crystal complex made by binding of anionic surfactant, sodium dodecyl sulfate (SDS), into high charge density cationic polymer, the homopolymer of diallyldimethylammonium chloride (PDADMAC) was induced by adding of nonionic surfactants and investigated by means of microscopy and FE.SEM. Among nonionic surfactants in this experiments polyethylene glycol (3 mol) ether of lauryl alcohol (laureth-3) made variation in the complex. The laureth-3 transformed the complex into spherulite vesicle with the size of ca.100μm. This change increased the viscosity and the turbidity of the solution phase separated originally. Microscope showed that they are spherulite particles and polarized microscope suggested they are multi.lamellar liquid crystals. FE-SEM also proved that explicitly.
        4,000원
        1818.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hemp seed oil and evening primrose oil were incorporated into the diets of laying hens for 5 weeks and the level of gamma fatty acid in the eggs that the treated hens laid was then evaluated. Hens were fed corn-soybean based diets that contained 5% tallow, 5% corn oil (CO), 5% hemp seed oil (HSO), or 5% evening primrose oil (EPO). The hemp seed oil and evening primrose oil influenced the amount of gamma linolenic acid found in the eggs through blood. The level of gamma linolenic acid in the plasma was significantly higher in hens that received the HSO and EPO diets than in those that received the tallow and CO diets. The HSO and EPO diets led to a 1.09% and 4.87% increase in egg gamma linolenic acids, respectively, when compared with eggs produced by hens treated with tallow and CO. Taken together, these data demonstrate that healthy eggs with increased gamma linolenic acids can be generated by minor diet modifications when hemp seed oil or evening primrose oil is included in the hen diet.
        4,000원
        1819.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recent years have brought remarkable developments in white light emitting devices (WLEDs) and white organic light-emitting devices (WOLEDs). However, their efficiency, CIE values, CRI and lifetime are still not ideal. This review covers detailed discussion about syntheses of organometallic complexes, inorganic phosphors and quantum dots used in WLEDs, WOLEDs and their electroluminescent properties until December 2007.
        5,700원
        1820.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study is focused on the antimicrobial activity of cyanobacteria Microcystis aeruginosa by the reduction and oxidation reaction of copper and zinc alloy metal fiber filter. Cu/Zn ion is easily makes radicals with molecular hydroperoxide. 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 and zinc alloy metal fiber is detected in the cyanobacteria solution as 0.5 ppm, and that of zinc ion is 0 ppm respectively. Zinc ion is figured to form a hydroxide in the cyanobacteria solution and precipitated to form a sludge. The concentration of chlorophyll-a in the cyanobacteria solution was proved to be the index of antimicrobial level of Microcystis aeruginosa.
        4,000원