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        검색결과 2,609

        2081.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As model waterborne acrylic coatings, mono-dispersed poly(butyl acrylate-methyl methacrylate) copolymer latexes of random copolymer and core/shell type graft copolymer were prepared by seeded multi-staged emulsion polymerization with particle size of 180~200 nm using semi-batch type process. Sodium lauryl sulfate and potassium persulfate were used as an emulsifier and an initiator, respectively. The effect of particle texture including core/shell phase ratio, glass transition temperature and crosslinking density, and film forming temperature on the film formation and final properties of film was investigated using SEM, AFM, and UV in this study. The film formation behavior of model latex was traced simultaneously by the weight loss measurement and by the change of tensile properties and UV transmittance during the entire course of film formation. It was found that the increased glass transition temperature and higher crosslinking degree of latex resulted in the delay of the onset of coalescence of particles by interdiffusion during film forming process. This can be explained qualitatively in terms of diffusion rate of polymer chains. However, the change of weight loss during film formation was insensitive to discern each film forming stages-I, II and III.
        4,000원
        2082.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        [Ga]-MFI and H-ZSM-5 catalysts were synthesized under atmospheric pressure and used in the propylene aromatization. The effect of temperature on the product distribution was also investigated. The catalytic activities of the prepared catalysts were compared with the commercialized H-ZSM-5 which was converted from NH4-ZSM-5. In the propylene aromatization, product distribution does not depend on the ratio of Si/Ga2 with [Ga]-MFI catalyst, but depend on the ratio of Si/Al2 with H-ZSM-5 catalyst [Ga]-MFI catalyst shows better dehydrogenation and alkylation activities than H-ZSM-5 catalyst The addition of Ga to H-ZSM-5 catalyst increases the conversion of propylene, selectivity to aromatics, and alkylation. In the propylene aromatization, the selectivity to aromatics slightly increased with increasing temperature with [Ga]-MFI catalyst, while slightly decreased with increasing temperature with H-ZSM-5 catalyst
        4,000원
        2083.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A silicone softner (SS-5), a permanent press (PP) finish, was prepared by blending silicone oil KF-96 (as a lubricating component) and beef tallow hardened oil (as a softening component) which was synthesized from fatty polyamide salts. The prepared SS-5 and the PP finishing resin were applied to PP finishing cotton cloth and P/C gingham sample by one-bath method. The properties such as crease recovery, tear strength, and bending resistance were tested. The samples treated with SS-5 and PP finishing resin showed improved properties when comparing with the untreated ones, with the ones treated only with PP finishing resin, with ones treated with commercial PP finishing softners and PP finishing resin. The grades of fabric samples treated with 3% SS-5 were fifth grade in the bending resistance test.
        4,000원
        2084.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Experimental Study was carried out for benzene desorption by purge gas or evacuation in an activated carbon bed. As purge gas flow rate increased, desorption rate increased due to the higher interstitial linear gas velocity. For various purge gas flow rates, desoption curves almost got together if they were plotted against dimensionless time. At a higher flow rate, mass transfer zone became narrower. Temperature drop in the bed was more fast and severe at higher flow rates and higher outer temperature. It was found out that desorption was almost completed when the temperature in the drop of the bed returned to the initial temperature before temperature drop. Desorption by vacuum purge was completed in shorter time than desorption by purge gas. Countercurrent purge was more effective than cocurrent purge.
        4,000원
        2085.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Diphosphine dinuclear gold(I) complexes were synthesized from the reaction of bridged diphosphines and gold ions. As a bridged diphosphine, 1,2-bis(diphenylphosphino)metbane (dppm) or 1,1'-Bis(diphenylphosphino) ferrocene (dppf) was introduced. As anionic ligands, CI was first coordinated to Au, resulting in (diphosphine)(AuCl)2. Then, the ligand, SPh, was substituted for Cl in the chloride complex to give (diphosphine)(AuSPh)2. As a result, three digold complexes, (dppm)(AuCl)2. (I), (dppf)(AuCl)2. (II), and (dppf)(AuSPh2. (III) were prepared in this study. The thermal properties were investigated at first hand to confirm that the gold complexes were in fact formed. The digold complexes were decomposed above 200℃ while the ligand, dppm or dppf, melts under 180℃ The photoluminescence (PL) spectra of the spin-coated thin films showed the maximum peak at 590, 595, and 540nm for the complex, I, II, and III, respectively. These complexes were found to give the orange color phosphorescence. Therefore, these digold complexes can be candidates for orange-red phosphorescent materials in organic electroluminescent devices (OELD). Further studies on application of the complexes as a dopant in an emitting layer are in progress in our laboratory.
        4,000원
        2086.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, the phosphorescent organic light-emitting devices (OLEDs) have been extensively studied for their high internal quantum efficiency. In this study, we synthesised several phosphorescent metal complexes, and certified their composition using NMR. We also investigated the characteristics of the phosphorescent OLEDs with the green emitting phosphor, Ir(ppy)3. The devices with a structure of indium-tin-oxide(ITO)/N,N'-diphenyl-N,N'-(3-methylphenyI-1,1'-biphenyl-4,4'-diamine (TPD)/metal complex doped in host materials/2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline(BCP)/tris (8-hydroxyquinolinato) Aluminum(Alq3)/Li:Al/Al was fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of tris(2-phenylpyridine)iridium (Ir(ppy)3), we fabricated several devices and investigated their characteristics.
        4,000원
        2087.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Oligomer type anionic surfactants(RmM-Na or RmD-Na were synthesized from C8~C16 long chain alkylvinylether and maleic anhydride (or maleic diethylether). And also their fluorescent anionic surfactants (RmF- Na) were obtained from alkali neutralization which opens the lactone ring of the condensing materials produced by maleic anhydride alkylvinylether copolymer and 3-aminophenol. The measurement results for the surface active properties of water soluble oligomer type anionic surfactants with fluorescent structure (RmF-Na) exhibited a remarkable surface tension lowing property, foam breaking property, and a ernulsing power.
        4,200원
        2088.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The cutaneous tolerability of detergent formulations can be improved by means of suitable additives. They complex the surfactant molecules lowering the concentration of their free monomeric species. Proteins derivatives used as additives for detergency are usually prepared by partial hydrolysis of plant reserve proteins. The main purpose of the hydrolytic cleavage is to make them water soluble and suitable for liquid products. Water solubility and stability are obtained by means of complexation with surfactants which also increase their actual hydrophobicity, an important parameter affecting cosmetic properties of proteins. Transepidermal water loss (TEWL) and electric capacitance (EC) have been adopted as investigation technigues to evaluate the skin integrity/damage in vitro tests, The performance of native wheat protein / surfactant complexes has been compared with traditional protein hydrolysates as detergent additives. The results show a noticeable reduction of skin irritation in surfactant formulations with addition of native wheat protein.
        4,000원
        2089.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The polyimide(PI) Langmuir-Blodgett(LB) ultra thin films were prepared by imidizing the PAAS LB films of PMDA and benzidine system with a thermal treatment at 250℃ for 30min, where the PAAS LB films were formed on substrates by using LB technique. The thicknesses of one layer of PAAS and PI LB film that deposited at the surface pressure of 27mN/m were 20.9 and 4A, respectively. At low electric field, ohmic conduction(I∝ V) was observed and the calculated electrical conductivity was about 4.23×10-15~9.81×10-15S/cm. The dielectric constant of LB film was about 7.0.
        4,000원
        2090.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have seen the effects of buffer layer in organic light-emitting diodes(OLEDs) using poly(N-vinylcarbazole)(PVK) depending on a concentration of PVK. Polymer PVK buffer layer was made using spin casting technique. Two device structures were fabricated; one is ITO/TPD/Alq3/Al as a reference, and the other is ITO/PVK/TPD/Alq3/Al to see the effects of buffer layer in organic light-emitting diodes. Current-voltage-luminance characteristics and an external quantum efficiency were measured with a variation of spin-casting rpm speeds and PVK concentration. We have obtained an improvement of external quantum efficiency by a factor of four when the PVK concentration is 0.1wt% is used. The improvement of efficiency is expected due to a function of hole-blocking of PVK in OLEDs.
        4,000원
        2091.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Natto is a Japanese traditional food made from whole soybeans by the fermentation of Bacillus natto. The purpose of this study was to investigate the effect of Natto mucilage on lipid metabolism in rats. The levels of total cholesterol, LDL-cholesterol and triglyceride in serum of rats fed Natto mucilage diets were lower than those in control rats, but serum HDL-cholesterol and phospholipid were higher than those in control rats. The results indicate that Natto mucilage may have more beneficial roles in lipid metablism because it decreased serum cholesterol and increased bilirubin excretion.
        4,000원
        2092.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Microemulsion is stable to aggregation, sedimentation, fusion and has 3nm~200nm of particle size which is transparent and semitransparent. The isoflavone as a derivatives of Flavone is colorless crystalline compounds. It has similar basic structure to steroid materials which is hormone that acts to skin physiological phenomenon. On this study, we tried to search and demonstrate system content rate of dermal translocation system for cosmetics using O/W type microemulsion containing isoflavone. We manufactured O/W microemulsions by phase inversion emulsification method. It's was found that POE(20) monostearate with HLB value 14 caused microemulsion to be formed, which had 4nm~18nm of average diameter and 3nm~33nm of particle size distribution. Apparent viscosities of the microemulsions have increased in proportion to add surfactant dose.
        4,000원
        2093.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We carried out this experiment to observe electrochemical properties for LB films of phospholipid(Dilauroyl-L-α-Phosphayidylcholine) and 4-octyl-4'-(5-carboxypentamethylene-oxy)azobenzene mixture by the cyclic voltammetry. LB films of 8A5H and 8A5H-DLPC(1:1, 2:1) were deposited by using the Langmuir-Blodgett method on the ITO glass. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference elect rode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in 0.1, 0.5, and 1.0 mol/L 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 were 50, 100, 150 and 200 mV/s. As a result, LB films of 8A5H 8A5H-DLPC appeared irreversible process caused by only the oxidation current from the cyclic voltammogram.
        4,000원
        2094.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We carried out this subject to observe photoisomerization using 1,2-dioleoyl-sn- glycero-3-phosphocholine(DOPC) mixed with fatty acid containing azobenzene group which has reversible to cis-trans by light irradiation. Spreading solutions for the LB films were prepared in chloroform(5.0×10-5mol/L).We investigated the photoisomerization and property of the organic ultra thin film of fatty acid containing azobenzene was prepared on the hydrophilic ITO(idium tin oxide) glass plate by LB method. As a result, the absorption spectra of 8A5H and DOPC of mixture LB films was induced to photoisomerization by alternating irradiation of ultraviolet and visible light, because the condensation of pure azobenzene monolayers was loosened by the introduction of phospholipid into the monolayers, and the molecular high aggregation in pure azobenzene monolayers is also weakened by the introduction of phospholipid. We found that it was reversibly induced to cis-trans photoisomerization in several solvents and mixture LB films.
        4,000원
        2095.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Copolymerization of α-Methylstyrene(AMS) with Acrylonitrile(AN) was carried out with benzoylperoxide(BPO) as an initiator in toluene at 80℃ in a continuous stirred tank reactor. Reaction volume and residence time were 0.6 liters and 3 hours, respectively. The monomer reactivity ratios, rAMS and rAN determined by both the Kelen-Tüdös method and the Fineman-Ross method were rAMS=0.16(0.14), rAN=0.04(0.06). The cross-termination factor Φ of the copolymer over the entire AMS composition ranged from 0.75 to 0.92. The Φ factors of poly(AMS-co-AN) were increased with increasing AMS content. The simulated conversions and copolymerization rates were compared with the experimental results. It was observed that the average time to reach dynamic steady-state was three times the residence time.
        4,000원
        2096.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Two PU flame-retardant coatings, 2,3-DBPO/N-l00 (DBPON) and 2,3-DBPO/IL (DBPOI), were prepared by curing 2,3-dibromo modified polyester (2,3-DBPO) with isocyanate curing agent Desmodur N-l00 (or Desmodur IL) at room temperature. The physical properties and flame-retardancy of the two coatings were tested and compared. As a result, the pot-life, yellowness index, lightness index difference, 60˚ specular gloss, cross-hatch adhesion, viscosity, and accelerated weathering resistance of DBPON were better than those of DBPOI; the fineness of grind of the two coatings were the same; and the drying time, hardness, and abrasion resistance of DBPOI were better than those of DBPON. The flame retardancy of the flame-retardant coatings increased with the content of the flame retarding component, 2,3-dibromopropanoic acid (2,3-DBP); and the LOI values of the two coatings were in a range of 27~29% when the content of 2,3-DBP was 30wt%.
        4,000원
        2097.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It is a great role that the character of man or woman could be distinguished by hair on the aspect of ornament. Hair will be support of beautifulness of human being in various permanent wave by many kinds of its drugs. Hair is based upon the skin which enroll the body of high living animals and have multiple membrane structure. This study used rat and the effects of commercial permanent wave products to skin which are composed with thioglycolic acid and bases. Results are as follows. Permanent wave penetrated to 4 hours later with steady state in skins and was not significant changeable after 20hr later. In case of neutralizer with thioglycolic acid lag time and permeability coefficient in healthy skin is 3.38hr and 0.094μg/cm2 · hr, it old skin is 3.48hr and 0.129μg/cm2 · hr, and it wounded skin is 4.72hr and 0.158μg/cm2 · hr. In conclusion, lag time and permeability coefficient in old skin and wounded skin are faster than healthy skin. In vivo which was studied by general time and method of permanent wave. We notified that fine rinkle and rash of skin were changeable in the case of treating with permanent wave drugs than normal skin. We can see even rash and eruption by the naked eye.
        4,000원
        2098.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, it should be mentioned that Lipid-LCG can be prepared with the main compound of hydrogenated lecithin in oil-in water emulsion. The results of its physical property and stability are as follows. First, the best suitable compositions of Lipid-LCG are made from 4.0wt% of the hydrogenated lecithin, 4.0wt% of cetostearyl alcohol as emulsifier and gelling agent, 3.0wt% of butylene glycol and 2.0wt% glycerin as moisturizers, 3.0wt% of cyclomethicone, 3.0wt% of isononyl-isononanoate, 3.0wt% of capric/caprylic triglycerides, 3.0wt% of macadamia oil as emollients. Second, As the optimum conditions to form Lipid-LCG, which figured out 6.0 ± 1.0 for pH level, 32kg/mm, min for hardness to make a .essence to be formed the ternary phase of liquid crystal(multi-lamellar type). Third, as the analytical result of this system, it obtained that particle size is 1~8μm level, and is certified with it at 400 and 1,000 magnifications by microscope. The stability of Lipid-LCG is very stable on condition of a low temperature (4℃), a room temperature (25℃) and a high temperature (40℃), which is not to be split in for a long time(for 3-month). We produced our own moisturizing essence, which has a good affinity to skin by means of this system.
        4,000원
        2100.
        2001.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The critical micelle concentration (CMC) at which micelles start to form from a surfactant solution is usually measured in terms of conventional concentration units. However, the thermodynamic potentials are expressed in terms of mole fraction XCMC and XCMC cannot be directly measured experimentally. The Gibbs free energy, δG*mic, in particular is related to XCMC through δG*mic = RTlnXCMC. When it comes to CMC, the molar CMC, CCMC, differs only by the proportionality C-1w with Cw being the molarity of water. Hence, CCMC is found to be a proper representation of CMC. However, in calculation of δG*mic and other thermodynamic potentials from the CMC, XCMC or CCMC/Cw should be used.
        4,000원