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        검색결과 2,609

        2221.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, high luminance and efficiency were realize in organic thin film electroluminescence (EL) cells with multilayer structures including an emitting layer (EML), hole transporting layer (HTL), and an electron transporting layer (ETL). In this study, Bis(10-hydroxybenzo[h]quinolinato)beryllium (Bebq2) was synthesized. PL and EL characteristics of their thin film were investigated by fabricating the devices having a structure of ITO/PVK/Bebq2/Al, ITO/PVK dispersed with TPD/Bebq2/Al. The EL color of these device was greenish and the wavelength of their EL peaks was located, respectly, at 495nm, and 492.5nm.
        3,000원
        2222.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We used Cu as a representative of metals to be directly adsorbed on the bare Si surface and studied its removal DHF, DHF-H2O2 and BHF solution. It has been found that Cu ion in DHF adheres on every Si wafer surface that we used in our study (n, p, n+, p+) especially on the n+-Si surface. The DHF-H2O2 solution is found to be effective in removing metals featuring high electronegativity such as Cu from the p-Si and n-Si wafers. Even when the DHF-H2O2 solution has Cu ions at the concentration of 1ppm, the solution is found effective in cleaning the wafer. In the case the n+-Si and p+-Si wafers, however, their surfaces get contaminated with Cu When Cu ion of 10ppb remains in the DHF-H2O2 solution. When BHF is used, Cu in BHF is more likely to contaminate the n+-Si wafer. It is also revealed that the surfactant added to BHF improve wettability onto p-Si, n-Si and p+-Si wafer surface. This effect of the surfactant, however, is not observed on the n+-Si wafer and is increased when it is immersed in the DHF-H2O2 solution for 10min. The rate of the metallic contamination on the n+-Si wafer is found to be much higher than on the other Si wafers. In order to suppress the metallic contamination on every type of Si surface below 1010atoms/cm2, the metallic concentration in ultra pure water and high-purity DHF which is employed at the final stage of the cleaning process must be lowered below the part per trillion level. The DHF-H2O2 solution, however, degrades surface roughness on the substrate with the n+ and p+ surfaces. In order to remove metallic impurities on these surfaces, there is no choice at present but to use the NH4OH-H2O2-H2O and HCl-H2O2-H2O cleaning.
        4,000원
        2223.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Algin is known as biodegradable natural polymer from marine plants. PVA/Algin blend films were prepared by solution blending method for the purpose of useful biodegradable polymer. Characteristics properties of PVA/Algin blend films such as DSC, Elongation, Tensile strength and Morphological change by SEM were determined. Tensile strength and Elongation were rapidly reduced as increasing the blend ratio of Algin. PVA/Algin blend films were found that phase separation was occured as more than 25wt% increasing the blend ratio of Algin. Blend films were observed to be less partially compatibility than 10wt% increasing the blend ratio of Algin by DSC, mechanical properties and SEM. Also, PVA/Algin blend films at the laboratory soil test(Pot Test) were completely degraded in months with four kinds of soils by microorganisms.
        4,000원
        2224.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sesame seed (Sesamum indicum L.) is an important seasoning in Korea and most korean consumer tend to eat the korean sesame seed as the best than other ones produced in oriental countries such as China and Japan. Near infrared reflectance spectroscopy (NIRS) was applied for discrimination according to geographical origin (Korea, China and so on) of sesame seeds. Near-infrared spectroscopy among the many kinds of techniques could provide a rapid screening, low cost solution to discriminate geographical origin of sesame seed. The objective of this study is to determine if NIR technique could be used to discriminate between the korean sesame seed and non-korean sesame seed by using the new method. Rapid, precise and nondestructive analysis method for determination of the geographic origin of sesame seeds were discriminated relative accurately according to geographical origin using PLS regression method.
        3,000원
        2225.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Photo-crosslinkable polyimide(PI) which contains CF3 moiety was synthesized. Polarized UV light transformed ketone group of PI to hydroxyl group, which was confirmed by IR and UV-visible spectroscopy. We investigated the dichroic UV-absorption before and after photo-reaction with linearly polarized light. In particular we have attempted to clarify the relationship between the anisotropy of surface region and surface azimuthal anchoring energy and knew that the anchoring energy of photo-alignment PI is comparable with that of mechanical rubbing.
        4,000원
        2226.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        계면활성제는 수용액에서 미셀을 형성함에 있어서 자기확산이 분자 운동과 상변화에 대하여 자세한 정보를 제공하고 공업적으로 응용할 수 있는 기술이 점차 증가하고 있다. 계면활성제가 미셀을 형성함에 있어 자기확산 정도는 화학구조의 변화성과 상호 결합 및 회합현상에 매우 민감한 것은 사실이다. 특히 계면활성제 용액의 넓은 범위의 분자 시스템과 콜로이드 상태의 변화성은 다향한 물리, 화학적 성질에 기여됨이 많다. 더욱이 미셀 형성에서 자기확산 계수는 분자 치환에 직간접적으로 상호관계가 있어 NMR 분광학에서 스핀 이완속도의 해석과 분자의 재배열, 스핀 이완에 대한 모델선정 등에 많은 관심을 갖는다. 그중 미셀형성에 있어서 자기확산에 대한 측정 방법중 가장 많이 이용되고 있는 Fourier Transform Pulsed Gradient Spin Echo(FT-PGSE) 측정법은 계면활성제의 미셀형성에 대한 상변화성 및 물리, 화학적 성질을 다루는데 새로운 도구로 제공되고 있다. 이는 이 계통의 기술적 측정방법에 있어서 적절한 개선과 새로운 응용분야를 확장하는데 있어서 많은 가능성을 갖고있다. 그리하여 이들에 대한 역사적 배경과 기초적인 이론을 가지고 미셀 형성에 있어 자기확산에 대한 개념을 말하고 그에 대한 응용성을 계통적으로 설명하고자 한다.
        4,600원
        2227.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In spite of various applications of chitin derivatives from waste marine sources, commercial use of chitin has been limited due to resistance to chemicals and the absense of proper solvents. We prepared chitin through decalcification, bleaching and deproteination from protunus trituberculatus shells by the application of Hackman's method. Structural and chemical properties of chitin were investigated to have proper specific surface area and particle size by IR, BET and PSA. The amount of absorbed water of chitin reached equilibrium by stirring about 15 minutes. The amount of absored water of the prepared chitin were large than the commercial chitin. When prepared chitin tested on dyeing wastewater, they showed better treatment efficiency in COD, suspended solid, and color tests than the commercial chitin. The adsorption capacity increased with decreasing particle size for the prepared chitin. Treatment efficiency for color was increased as the sitirring rate increased. Results show the possibility of the prepared chitin from waste marine sources as a treatment system for dyeing wastewater.
        4,000원
        2228.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        CuxFe3-xO4 catalyst and ZnxFe3-xO4 catalyst were synthesized by the air oxidation method with various C(II) and Zn(II) weights. Activated catalysts decomposed carbon dioxide to carbon at 350℃, 380℃, 410℃ and 440℃. The value of carbon dioxide decomposition rate for Cu0.003Fe2.997O4 and Zn0.003Fe2.997O4 catslysts than was better catalysts. The decomposed rate of the catalysts is about 85%~90%. The reaction rate constant(4.00 psi1-α/min) and activation energy(2.62 kcal/mole) of Cu0.003Fe2.997O4 catalyst are better than Zn0.003Fe2.997O4
        4,000원
        2229.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Gum is known as natural polymer. Biodegradable films were prepared by solution blend method in the weight ratio of natural gums(Xanthan, Locust bean, Guar) for the purpose of useful bioimplants. The possibility of bioimplants, which prepared from natural gums as a skin substitute was evaluated by measuring biodegradability. This biodegradable films were inserted in the back of rats and their of biodegradability were investigated by hematological change evaluation as a function of time to the biotransformation. Rats implantation test results showed that Guar induced increments of monocyte and basophil after 48 hours of implantation. And Locust bean showed increase of monocyte and neutrophile counts after 48 hours of implantation. And Xanthan induced decrease of monocyte and neutrophile at 24 hours after implantation. Guar and Locust showed high hemoglobin contents and hematocrit after 48 hours of implantation. Guar and Locust induced some suspects of incompatibility in the tissue after 48 hours, but three were little effects to the skin inflammation at 24 hours. These values of biodegradable films, which prepared from prepared from natural gums measured in this were some satisfiable results at short period with those of ideal skin bioimplants.
        4,000원
        2230.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The beeswax sample was collected from the beehives, isolated and then refined. The first step of producing beeswax was to separate honey from beehives. The beehives which were cut put in hot water. The upper layer was crude beeswax, which was treated with phosphoric acid. The crude beeswax was purified through the bleaching. The objectives of this study are to identify headspace volatile compounds and to know the contents of α-carotenes and β-carotenes of korean beeswax. Headspace volatile compounds of Korean beeswax were measured by using the combination of dynamic headspace sampler (DS 5000, Donam System Inc.), gas chromatography and mass selective detector (HP5890 & 5971, Hewlett Packard). Seventy five compounds identified from about 100 peaks by analyzing the purified beeswax were 60 hydrocarbons, 8 carbonyls, 4 essential oils, 3 esters. Carotenes of Korean beeswax were analyzed by using High Performance Liquid Chromatography (Waters Inc.). As A result, the content of α-carotenes and β-carotenes were 0.07ppm, 0.011ppm individually.
        4,000원
        2231.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a new conducting materials, namely, a Schiff base (polymeric azomethine) was synthesized from 2,6-diamino-N-docosyl pyridinium bromide and terephthalaldehyde to obtain a soluble and fusible conducting polymer. The synthesized Schiff base structure was analyzed by using UV/vis absorption spectrophotometer, FT-IR spectrometer and 1H-NMR spectrometer. It was found that the Schiff base was successfully synthesized and soluble in carbon tetrachloride(CC14), its Langmuir-Blodgett film was easily fabricated, and its surface pressure was determined to be 30mN/m for solid state by measuring π-A isotherm.
        4,000원
        2232.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methyl fructoside oleic acid polyester(MFPE), fructose-based sugar polyester, was synthesized by solvent-free, soap-free transesterification of methyl oleate with methyl fructoside(MF) as a sugar starting material in the presence of conventional potassium carbonate basic catalyst. Methyl fructoside was found to be an effective sugar starting material, because of its low softning point, high heat stability, high miscibility, and high reactivity than other sugars. Yield 98% of purified MFPE based on initial weight of MF was obtained at 1:5 of the molar ratio of methyl fructoside to methyl oleate, 2%(w/w) of potassium carbonate catalyst content, 20~200mmHg of reduced pressure and 180℃ of reaction temperature. MFPE structure was confirmed by infrared and proton nuclear magnetic resonance spectroscopy. Physical properties of methyl of fructoside oleic acid polyester such as viscosity, HLB, solubility, color, refractive index, specific gravity, and density were similar to physical properties of sucrose polyesters(SPE) and vegetable oils. Then, it was elucidated that MFPE was sufficient to replace the SPE and conventional oils.
        4,300원
        2233.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        All the triacylglycerols including the molecular species having δ5-unsaturated fatty acids from the seeds of Pinus Koraiensis, were split into a mixture of diacylglycerols by a Grignard reagent prepared with allyl bromide without arousing acyl chains of a glycerol moiety to migration, and were also easily partially hydrolyzed to diacylglycerols by pancreatic lipase. (S)-(+)-(1-naphthyl)ethyl urethane(NEU) derivatives of the diacylglycerol mixture derived from the triacylglycerols were fractionated into sn-1, 3-, sn-1, 2- and sn-2, 3-DG-NEU by silica-HPLC and the fatty acid composition of these fractions was analysed. C18:1Ω9 is distributed evenly in the three positions of TG with C18:2Ω6 mainly located in sn-2 position, while δ5-unsaturated fatty acids such as δ5.9-C18:2, δ5.9.12-C18:3 and δ5.11.14-C20:3 are exclusively present in the sn-3 position. These results could be confirmed by 13C-NMR spectroscopy : the signals at δ173.231 ppm and δ172.811 ppm of the carbonyl carbon of acyl moieties indicate the presence of saturated acids and/or C18:1Ω9 (oleic acid) in the α(α')- or β- positions, and C18:2Ω6 including C18:1Ω9 in the β-position, respectively. In addition, the resonance at δ173.044 ppm suggested a location of δ5-unsaturated fatty acid moiety in the α(α')-position.
        4,000원
        2234.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The natural body foam product which palm oil is added to this product, differs from products for clothes and Kitchen detergent, industrial and domestic detergent, and It has a various characteristics as a soft detergent for bath and hair product. Up to now, vidal sassoon product which imports form overseas and sells in our country, increases every year in consumption quantity. The development of this product tested to consider the quality of product in the effect of import transfer. First of all, the experiment of this product tested the fundamental items of pH, foam formation force, the moisture effect of product, the biodegradation degree of product. In case of palm oil, when it was added to this product in 0.25wt%, we could get experiment results that pH appeared in 6.2, foam formation force in product 1wt% solution appeared in 104ml per 30sec, the skin moisture effect of product appeared in incleasing from 82 a.u to 90 a.u within one hour since we have used the product, the biodegradation degree of surfactant appeared in 96.7%. According to the experiment result of product, we could know the fact that it has a high quality in comparison with other products.
        4,000원
        2235.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Organic-based electroluminescent devices have attracted lots of interests because of their possible application as a large-area flat panel display. Polyimides have been used for photo-alignment in LCD(Liquid Crystal Display). However, the devices used in this study were fabricated with polyimide doped with N,N'-Diphenyl-N,N'-di(m-tolyl)-benzidine(TPD) (3, 10, 30wt%) for electroluminescent hole tranforting layer(EHTL). The photochemical and physical properties of EHTL was studied. The film thicknesses were reduced under illumination with UV light. Polyimide films doped with TPD(3wt%) was irradiated and the electrical properties of the films were studied.
        4,000원
        2236.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The propagation of light radiation in a turbid medium is an important problem that confronts dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. Scattered light is measured as a function of the position(distance r, depth z) between the axis of the incident beam and the detection spot. Turbid sample yields a very forward-directed scattering pattern at short range of position from source to detector, whereas the thicker samples greatly attenuated the on-axis intensity at long range of position. The portions of scattered light reflected from or transmitted throughphantom depend upon internal reflectance and absorption properties of the phantom. Monte Carlo simulation method for modelling light transport in tissue is applied. It uses the photon is moved a distance where it may be scattered, absorbed, propagated, internally reflected, or transmitted out of tissue. The photon is repeatedly moved until it either escape from or is absorbed by the phantom. In order to obtain an optimum therapeutic ratio in phantom material, optimum control the light energy fluence rate is essential. This study is to discuss the physical mechanisms determining the actual light dose in phantom. Permitting a qualitative understanding of the measurements. It may also aid in designing the best model for laser medicine and application of medical engineering.
        4,000원
        2237.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The lipids from the seeds of Pinus koraiensis mostly composed of triacylglycerols (TGs), in which linoleic acid (46.2 mol%) and oleic acid (25.6 mol%) are present as main components in the fatty acid composition. Surprisingly, they also have unusual fatty acids with δ5-double bond systems such as δ5.9.12-C18:3 (16.0 mol%), δ5.9-C18:2 (2.3 mol%) and δ5.11.14-C20:3 (0.8 mol%). Saturated fatty acids of palmitic, stearic and arachidic acid were present in less than 8.0 mol%. TG was resolved into 17 fractions by reverse-phase HPLC according to so-called partition number (PN) suggested by Plattner, in which TG molecules with δ5-NMDB acyl chains eluted later than did those with δ9-MDB acyl radicals. Ag+-HPLC separated the TG into 14 fractions more clearly than did those with δ9-MDB acyl radicals. Ag+-HPLC separated the TG into 14 fractions more clearly than did reverse-phase HPLC, and the complexity of δ5.9.12-C18:3 moiety with silver ion impregnated in the column bed was in the level between δ9.12.15-C18:3 (C18:3Ω3) and C18:2Ω6 (δ9.12-C18:2). In the Ag+-HPLC, it was found that the molecular species having a given-numbered double bonds widely spreaded in the acyl chains eluted earlier than those concentrated in one acyl chain. The main molecular species are (C18:2Ω6)2/δ5.9.12-C18:3 (14.8 mol%), C18:1Ω9/C18:2Ω6)2 (12.8 mol%) and C18:1Ω9/C18:2Ω6/δ5.9.12-C18:3 (10.9 mol%).
        4,000원
        2238.
        1998.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The saturated fatty acids(arachidic acid, stearic acid, and palmitic acid) were repeatedly applied on water surface, and their π-A isotherms and Maxwell displacement current(MDC) were measured to identify the effect of the number of carbons of fatty acids on the properties of Langmuir films. The saturated fatty which contain higher carbon number showed higher MDC peak, and the less carbon it contains, the higher surface pressure they show. It was found the maximum of MDC peaks was as the molecular area just before the surface pressure increases in compression cycles of saturated fatty acids.
        4,000원
        2239.
        1998.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, organic electroluminescent devices(OELD) with a structure of a glass substrate/ITO/TPD/Tb(ACAC)3(Phen-Cl)/Alq3/Al was fabricated by vacuum evaporation method, where Tb complex was known to have green light emitting property. Electroluminescent(EL) and I-V characteristics of this structure were investigated. This triple-layer structure shows the green EL spectrum at the wavelwngth of 546nm, which is almost the same as the PL spectrum of Pb(ACAC)3(PhenCl). It was found in current-voltage(I-V) characteristics of the devices that the operating voltage was about 12V.
        4,000원
        2240.
        1998.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Two-component polyurethane flame retardant coatings were prepared by blending phosphate-containing modified polyesters(PMPEs) and TDI-adduct. PMPEs were synthesized by polycondensation of dimethyl phenylphosphonate, a flame retardant component, with 1,4-butanediol, adipic acid, and trimethylolpropane. The content of dimethyl phenylphosphonate was varied 10, 15, and 20wt% for the reaction. Various physical properties of these new flame retardant coatings were comparable to non-flame retardant coatings. Coatings with 20wt% dimethyl phenylphosphonate did not burn during the vertical burning test.
        4,000원