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        검색결과 2,503

        1741.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The surface of poly(ethylene naphthalate) film applicable to high temerature insulator for convection microwave oven was modified with silicone coating solutions in the presence of silane crosslinking agent. The structure and properties of the PEN films were investigated by using Fourier transform IR spectroscopy, viscometry, microscopy, and tensile tests. The experimental results showed that the coating with silicone enhanced thermal stability up to 200℃, and slightly lowered the tensile strength and elongation of the PEN films. Judging from dimensional stability results the silicone coated PEN films can not be used for higher temperature insulator above 230℃. Serious dimensional contraction of films was obtained during heat treatment at 250℃ even for 1h. However, the surface of those films still have same chemical structure of silicones. Therefore, If we use PEN film prestretched at 230℃ as base one it will be possible to prepare a high temperature insulator up to 230℃. Conclusively, a silicone coated PEN film can be suitable for the application to convection microwave oven door insulator at high temperature up to 230℃.
        4,000원
        1742.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rheological properties and surface tensions of polymer solutions and polymer-surfactant mixed solutions were investigated. The polymers used in this study were a homopolymer of acrylic acid crosslinked with an allyl ether of pentaerythritol, an allyl ether of sucrose, or an allyl ether of propylene (CARBOMER), acylate/C10-30 alkyl acylate crosspolymer (AAAC), and ammonium acryloydimethyltaurate/VP copolymer (ADTV). A solubilizing agent PEG-40 hydrogenated castor oil (HCO-40) and an emulsifying agent polyoxyethylene (20) sorbitan monostearate (POLYSORBATE 60) made the micelles intervening between AAAC polymers, resulting in the increase of viscosity. However, HCO-40 made this behavior over the wider range of surfactant concentration than POLYSORBATE 60. From the view point of surface tensions in the same range of surfactant concentration, AAAC/HCO-40 solution showed the area of increasing surface tension with surfactant concentration in contrast to the AAAC/POLYSORBATE 60 solution showing no increasing area.
        4,000원
        1743.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prepare high-solid coatings, acrylic resins, HSCs [poly (EA/EMA/2-HEMA/CLA)] that contain 90% solid, were synthesized by copolymerization of ethyl acrylate (EA), ethyl methacrylate (EMA), 2-hydroxyethyl methacrylate (2-HEMA) and caprolactone acrylate (CLA). The high-solid coatings named as CHSCs (HSCs/HDI-trimer) were prepared by the curing reaction between the acrylic resins containing 90% solid contents and the isocyanates (HDI-trimer) curing agent room temperature. The curing behavior and various properties were examined on the film coated with the both high-solid coatings. The glass transition temperatures (Tg) of CHSCs increased proportionally with increasing the predicted Tg value by Fox equation, and had nothing to do with the solid contents. The prepared film showed good properties for 60˚ specular gloss, impact resistance, cross-hatch adhesion and heat resistance, and bad properties for pencil hardness, drying time, and pot-life. Among the film properties, the heat resistance was very excellent and could be explained by the introduction of functional monomers of CLA.
        4,200원
        1744.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As an additional high purification method of p-dioxanone monomer for a high molecular weight polymer, the sweating operation of crystalline layer obtained by layered melt crystallization from p-dioxanone-diethylene glycol system was studied. Purity and yield of p-dioxanone crystal depended mainly on the sweating temperature and sweating time. Increasing sweating time and sweating temperature, the purity of p-dioxanone crystal increase, whereas the yield of that decrease, respectively. Through the optimization of sweating operation, p-dioxanone crystal can be upgraded to very high purity over 99.9 % suited to monomer for polymerization.
        4,000원
        1745.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to obtain the maximum flame retardancy with the minimal deterioration of physical properties of PU flame-retardant coatings, chlorine and phosphorous 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 kind of intermediates to obtain copolymer. The modified polyesters containing chlorine and phosphorous (ATBA-10C, -20C, and -30C) were synthesized by adjusting the contents of chlorine compound (dichloroacetic acid, 10, 20, 30 wt%) with fixed the content of phosphorous compound (2 wt%). The PU flame-retardant coatings (TTBAH -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 phosphorous were inferior to those with phosphorous 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 1st grade flame retardancy. 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 results of flame retardancy tests of the specimens that contain the same amounts of flame retarding compounds, it was found that the coatings containing both phosphorous and chlorine show higher flame retardancy than the coatings containing phosphorous alone. This indicates that some synergy effect of flame retardancy exists between phosphorous and chlorine.
        4,900원
        1747.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2-Chlorobenzoyl hydrazine refluxed with benzoyl isothiocyanate and phenyl isothiocyanate in ethanol for 3 hours to give benzamide derivative (1) and anilinederivative (2) on yield of 71%and 95%, respectively. Benzamide derivative (1) reacted with ethanolic sodium hydroxide on reflux to afford cyclization product (3), followed by general substitution reaction of two steps to give acetamide (5), and derivatived acetamides 7a-7k, while aniline derivative (2) reacted with ethanolic sodium hydroxide on reflux to afford another cyclization product (4). Thiol (4) reacted with N-phenyl chloroacetamide in the presence of potassim carbonate to give acetamide derivative (6). Compounds 1-7kwere evaluated for their growth inhibition against five cancer cell lines, including human lung carcinoma (A-549), human prostate cancer (DU145), human colon adenocarcinoma (HT-29), human malignant melanoma (SK-MEL-2) and human ovary malignant ascites (SK-OV-3) with sulforhodamine B (SRB) assay. All compounds (1-7k) showed low inhibition activities under 50% on 100M concentration.
        4,000원
        1748.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The cosmetic and toiletries are necessary health care & household for common life. However we need antiseptic which is effecting harmlessly to the human body. There are propolis, Lavender, Lemon, essential oil in the natural antiseptic materials. This work proceeded design Natural-antiseptic system with three materials as above-mentioned. Natural-antiseptic system was accomplished with propolis (2%), Lavender essential oil (0.3%), Lemon essential oil (0.3%) safety out of Polysorbate 20 (0.5%), Polysorbate 80 (0.5%), PEG (60) hydrogenated castor oil (0.45%), ethanol (5%). The antimicrobial test was experimented on E. coli and Bacillus stearothermophilus. In this antimicrobial test, we found that the effect of antisepsis against E. coli and Bacillus stearothermophilus with propolis 0.3%, Lavender essential oil 0.045% and Lemon essential oil 0.045% was improved. Therefore could expect Natural-antiseptic system product for moisturizing skin toner for face, nourishing essence and wet tissue for clean other things.
        4,000원
        1749.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present paper deals with gaseous carbon dioxide separation by a commercial adsorbent: X-type zeolite. Experimental work was carried out at an ambient condition focusing on how well meeting to the national guideline. A few types of reactor and material were examined, and practical capability was found in a granular bed type reactor with the flow of 2.5 CMM. An optimum design of reactor and adsorbent could provide the required concentration, less than 2500 ppm, for the continuous operation up to 10 hours. More work including automatic regeneration is now underworking.
        4,000원
        1750.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Gasohol, which is combined solution of gasoline and ethanol, is difficult to apply to the field, because it usually brings phase separation by mingling of water. We investigated phase separation by adding different concentrations of "Ethanol", anhydrous and fermentative, to "Gasolines", gasoline, gasoline base and naphtha, Placing ethanol itself open to the air, the concentrations of water are increased in length of time. The phase separation temperatures of the gasolines-ethanol solutions have dropped in the following order : gasoline, gasoline base and naphtha. When adding water to the solutions of gasolines and anhydrous ethanol, the temperatures of phase separation is higher when the concentration of water increases more. Thus, it is obvious that the water is sensitive in phase separation.
        4,000원
        1751.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The diffusion behavior of phenol, toluene and benzoic acid in aqueous SDS solution was examined. It showed a similar experimental results for phenol and toluene. The diffusion coefficients of the solutes were characterized by the presence of two distinct regions: below the cmc and above the cmc. For phenol and toluene, it remained approximately unchanged when the SDS concentration was below the cmc. Above the cmc there was an apparent decrease in the diffusion coefficients of the two solutes with increasing SDS concentration. However, for benzoic acid the diffusion behavior was different from that of phenol and toluene. The diffusion coefficient of benzoic acid decreased slightly with increasing SDS concentration, however the diffusion coefficient was almost constant above the cmc. For benzoic acid the diffusion behavior was dependent on the joint contribution of benzoic acid molecules as well as the benzoate ions.
        4,000원
        1752.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A new blue phosphorescent material for organic light emitting diodes (OLEDs), Iridium(III)bis[2-(4-fIuoro-3-benzonitrile)-pyridinato-N,C2'] picolinate (Firpic-CN), was synthesized and studied. We compared characteristics of Firpic-CN and Bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) which has been used for blue dopant materials frequently. The devices structure were indium tin oxide (ITO) (1000 a)/N,N'-diphenyl-N,N'-(2-napthyl)-(1,1'-phenyl)-4,4'-diamine (NPB) (500 a)/4,4'-N,N'-dicarbazole-biphyenyl (CBP) : FIrpic and FIrpic-CN (X wt%)/4,7-diphenyl-1,10-phenanthroline (BPhen) (300 a)/lithum quinolate (Liq) (20 a)/Al (1000 a). 15 wt% FIrpic-CN doped device exhibits a luminance of 1450 cd/m2 at 12.4 V, luminous efficiency of 1.31 cd/A at 3.58mA/cm2, and Commission Internationale d'Eclairage (CIEx,y) coordinates of (0.15, 0.12) at 12 V which shows a very deep blue emission. We also measured lifetime of devices and was presented definite difference between devices of FIrpic and FIrpic-CN. Device with FIrpic-CN as a dopant presented lower longevity due to chemical effect of CN ligand.
        4,000원
        1753.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methane combustion over perovskite catalysts was investigated. For the preparation of catalysts, Co, Mn, Fe, and Ni were used as B-site components of the perovskite catalysts (ABO3) and La was used as A-site component. The effect of calcination temperature on methane combustion and perovskite structure was also investigated. The structure of perovskites, surface area, and adsorbed oxygen species were tested with XRD, BET apparatus, and O2-TPD, respectively. The formation of perovskite structure was affected by the calcination temperature. The catalyst desorbing oxygen at a lower temperature showed better activity for the methane combustion, therefore, the oxygen species desorbing at lower temperatures is responsible for the methane combustion.
        4,000원
        1754.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        X-ray diffraction studies have been made to investigate the effects of binding of ADP, ADP+Vi, ADP+AIF4, ADP+BeF3 on the structure of glycerinated rabbit skeletal muscle in the rigor state. Although these phosphate analogs are known to bind actively cycling myosin heads, it is not clear whether they can bind to the attached heads in the rigor muscle. We have found that these analogs can bind to the myosin heads attached to actin filaments in the rigor state. The present results indicate that (1) bound myosin heads altered their conformation in the proximal end toward the plane perpendicular to the fiber axis when MgADP bound to them, and (2) myosin heads were dissociated substantially (up to 50%) from actin filaments but still remained in the vicinity of actin filaments when MgADP and metallofluorides (AIF4 and BeF3) or vanadate bound to them. We detected new conformations of myosin heads attached to actin filaments when they had MgADP or ADP.Pi analogs. We report here these findings on the effects of MgADP and MgADP+phosphate analogs to the rigor crossbridges.
        4,000원
        1755.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 논문에서는 게이트 절연막 위에 vapor deposition polymerization(VDP)방법을 사용하여 성막한 유기 점착층을 진공 열증착하여 유기 박막 트랜지스터(OTFTs)소자를 제작할 수 있음을 증명하였다. 우리가 제작한 Staggered-inverted top-contact 구조를 사용한 유기 박막 트랜지스터는 전기적 output 특성이 포화 영역안에서는 포화곡선을, triode 영역에서는 비선형적인 subthreshold를 확실히 볼 수 있음을 발견했다. 0.2μm 두께를 가진 게이트 절연막위에 유기 점착층을 사용한 OTFTs의 장 효과 정공의 이동도와 문턱전압, 그리고 절멸비는 각각, 약 0.4cm2/Vs, -0.8V, 106 이 측정되었다. 게이트 절연막의 점착층으로써 폴리이미드의 성막을 위해, 스핀코팅 방법 대신 VDP 방법을 도입하였다. 폴리이미드 고분자막은 2,2bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride(6FDA)와 4,4'-oxydianiline(ODA)을 고진공에서 동시에 열 증착 시킨 후, 그리고 150℃에서 1시간, 다시 200℃에서 1시간 열처리하여 고분자화된 막을 형성하였다. 그리고 점착층이 OTFTs의 전기적 특성에 주는 영향을 설명하기 위해 비교 연구하였다.
        4,000원
        1756.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The acenaphthene(ACE) or acenaphthylene(ACEL) is one of the most frequently found compound in polycyclic aromatic hydrocarbon (PAH)-contaminated soil. In this study, we make 10mg/L ACE or ACEL in ethanol which is the model washing solvent for contaminated soil. This was followed by Fenton treatment in which 0.2 or 0.3mL of 30% H2O2 and 0.2 ml of 0.5 M Fe2+ were added. The results showed more than 88 or 99% of ACE or ACEL removal efficiency, respectively. Additionally, we employed GC-MS to identify the main oxidation product generated by the optimized Fenton oxidation [i.e., ACE or ACEL degraded in to 21, 34 % 1,8-naphthalic anhydride(NAPAN), repectively]. It is expected that biodegradability of NAPAN is enhanced because NAPAN has three oxygens compared with ACE and ACEL. Therefore the results suggest that the hybrid treatment system (i.e., ethanol washing -Fenton oxidation treatment) can be effectively applied to remove ACE or ACEL from soil..
        4,000원
        1757.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was focused on the maximization of flame-retardancy of polyesters by a synergism of simultaneously introduced chlorine and phosphorus into polymer chains of modified polyesters. To prepare modified polyesters, reaction intermediates, TD-adduct (prepared from trimethylolpropane/2,4-dichlorobenzoic acid (2,4-DCBA)) and TMBO (prepared from tetramethylene bis(orthophosphate)), were prepared first, then condensation polymerization of the prepared intermediates, adipic acid, and 1,4-butanediol were carried out. In the condensation polymerization, the content of phosphorus was fixed to be 2%, and the content of 2,4-DCBA that provides chlorine component was varied to be 10, 20, and 30wt%, and we designated the prepared modified polyesters containing chlorine and phosphorus as ABTT-10C, -20C, -30C. Two-component PU flame-retardant coatings (ABTTC, ABTTC-10C, ABTTC-20C, ABTTC-30C) were prepared by the curing of synthesized ABTTs with a curing agent of allophanate/trimer at room temperature. To examine the film properties of the prepared PU flame-retardant coatings, film specimens were prepared with the prepared coatings. The film properties of ABTTC, ABTTC-10C and ABTTC-20C, which contain 0, 10 and 20wt% 2,4-DCBA, respectively, were proved to be good, whereas the film properties of ABTTC-30C, which contains 30wt% 2,4-DCBA, was proved to be a little bit poor. Two kinds of flame retardancy tests, ˚45Meckel burner method and LOI method were performed. With the ˚45Meckel burner method, three flame-retardant coatings except ABTTC showed less than 3.4cm of char length, and showed less than 2 seconds of afterflaming and afterglow. From this result, the prepared flame-retardant coatings were proved to have the 1st grade flame retardancy. With the LOI method, the LOI values of the coatings containing more than 10wt% 2,4-DCBA were higher than 30%, which means that the coatings possess good flame retardancy. From these results, it was found that synergistic effect in flame retardancy was taken place by the introduced phosphorus and chlorine.
        4,900원
        1758.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Kevlar was chemically surface modified with resorcinol-formaldehyde(RF) prepolymer and VP rubber latex for application to high strength tirecords. RF prepolymer was easily obtained by polymerization at room temperature in the presence of a base catalyst. The mechanical and thermal properties of Kevlar were not significantly changed during surface treated under various conditions. The change of adhesion with rubber were investigated through H-test method. Maximum increase of adhesion force between rubber and Kevlar was obtained up to 40% than that of untreated one when the fiber was soaked in RFL dipping solution and thermally treated at 170℃ for 3 - 5min.
        4,000원
        1759.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To prepare weather-resistant silicone/acrylic resin coatings for an architectural purpose, tetrapolymers were synthesized by a radical polymerization. 3-Methacryloxypropyltrimethoxysilane (MPTS) as a silicone monomer and n-butyl acrylate, methyl methacrylate, and n-butyl methacrylate as acrylic monomers were used. The compositions of monomers were adjusted to fix the glass transition temperature of acrylic polymer for 20℃. The composition of MPTS in the synthesized polymer were varied from 10 wt% to 30 wt%. On the basis of synthesized resin amber paints were prepared and their physical properties and effects for weatherability were examined. The presence of MPTS in silicone/acrylic resins generally resulted in low molecular weight and broad molecular weight distribution, and also lowered the viscosity of the copolymers. The coated films prepared from these resins showed good and balanced properties in general. Adhesion to the substrate was outstanding in particular. Weatherability tests were carried out in three different types such as outdoor exposure, QUV, and SWO. The test results showed that the silicone/acrylic resins containing 30 wt% of MPTS had weather-resistant properties.
        4,500원
        1760.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It prepared the TiO2 powder which has photo-catalytic activity in the visible-light by the wet process with titanium oxysulfate. The titanium dioxide(TiO2) by the wet process creates a new absorption band in the visible light region, and is expected to create photocatalytic activity in this region. Anatase TiO2 powder which has photocatalytic activity in the visible light region, is treated using microwave and radio-frequency(RF) plasma. But, the TiO2 powder for the visible light region, which also can be easily produced by wet process. The wet process TiO2 absorbed visible light between 400nm and 600nm, and showed a high activity in this region, as measured by the oxidation removal of aceton from the gas phase. The AH-380 sample appears the yellow color to be strong, the catalytic activity in the visible ray was excellent in comparison with the plasma-treated TiO2. The AH-380 TiO2 powder, which can be easily produced on a large scale, is expected to have higher efficiency in utilizing solar energy than the plasma-treated TiO2 powder.
        4,000원