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        검색결과 98

        62.
        2006.04 구독 인증기관·개인회원 무료
        Synthesis of zinc oxide nanorods, sheets and flower like structure were done by the sol-gel method using zinc acetate dihydrate and sodium hydroxide at with 12 hours refluxing time nanorods, in case of as synthesized powder, with diameter of 20-60nm. Annealing at higher temperature (300 and ,) in air ambient changes the morphology to sheet and flower like structure. The standard peak of zinc oxide was observed in IR at . The UV-VIS spectroscopy of zinc oxide shows a characteristic peak at 375nm.
        63.
        2006.04 구독 인증기관·개인회원 무료
        Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and pore size distribution. Hematite phase shows crystalline structures. The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the X-ray diffraction. The BET and pore size method were employed for specific surface area determination.
        64.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, silver-doped antibacterial hydroxyapatites were successfully prepared by the sol-gel method. For the starting solution, the molar ratio of was set to 0.075:0.045:20:0.135; was added to a ratio of Ag to total cation concentration of . The prepared sol was dried at for 48h and heat-treated at for 2h to obtain particles in the 200-500nm size range. The product from the synthesis of silver-doped hydroxyapatite was investigated through X-ray diffraction experiments and scanning electron microscopy. The product showed high antibacterial properties, with a disinfection ratio of Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922) over as calculated from an antimicrobial effects evaluation by the shake flask method.
        4,000원
        67.
        2004.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An aqueous solution of a commercial liquid synthetic detergent for kitchen use was photodecomposed in the presence of titanium dioxides powder under an atmosphere of air at room temperature. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio(H2O/titanium iso-propoxide) and calcined at 500℃. All titanium dioxides were characterized by XRD, BET surface area analyzer and UV-VIS spectrometer. The surface area of titanium dioxides prepared at R ratio=6 appeared higher volume about 20% than commercial TiO2 catalysts. XRD patterns of titania particles were observed mixing phase together with rutile and anatase type. Titanium dioxides prepared by sol-gel method show higher activity about 6% than commercial TiO2 catalysts on the photocatalytic degradation of a commercial liquid synthetic detergent for kitchen. The concentration of the detergent decreased to about 90% of its initial value at illumination times of 2 hour. Illumination for 30 minutes decreased the concentration of oxygen to about one-fifth of the initial value.
        4,000원
        68.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        BaTiO3, powders were prepared by sol-gel process from different aging time and reaction temperature. Particle shape, size and crystal structure of prepared BaTiO3 powders were analyzed by SEM, XRD and FT-IR. Effect of aging time alternation didn't particularly show up. Spherical nano-sized BaTiO3 powders were obtained from condition more than reaction temperature 55℃, and obtained sintered BaTiO3 powders of tetragonal phase from heat-treatment at 1,100℃.
        4,000원
        75.
        2001.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        고온에서 수소 분리 회수를 목적으로 silica/alumina 복합 막을 합성하였다. 막의 선택 투과 성능을 향상시키기 위해, sol-gel법에 의한 silica 및 alumina층을 중간층으로 도입하고, 그 위에 강제유동 CVD법에 의한 silica를 합성하였다. Sol-gel법에 의해 alpha-alumina tube에 합성한 gamma-alumina 및 silica 막은 Knudsen 확산 영역의 많은 mesopore를 포함하고 있어서 수소 선택 분리 막으로는 적합하지 못했다. 하지만, sol-gel법에 의해 합성한 silica/gamma-alumina층에 강제유동 CVD법으로 silica를 합성한 결과, 질소 투과 영역의 세공이 완전히 제거되어, 높은 수소 선택성을 가지는 복합 막이 형성되었다. 그 막은 온도에 따라 수소 투과 속도가 증가하여 450℃에서 5.57times10-8molm2sLPa1의 수소 투과 속도와, 9.52 kJ/mol의 활성화 에너지를 나타냈다. 분자체 효과에 의해 질소 투과가 완전히 배제되고, 수소만 선택적으로 투과되는 silica/alumina 복합막이 성공적으로 합성된다.
        4,000원
        77.
        2001.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The transparent organic-inorganic hybrid films were prepared by the Sol-Gel process. PVP(polyvinylpyrrolidone) was used in organic component and TEOS(tetraethoxysilane) was used in inorganic component. HCI, CH3COOH, and NH4OH were used as the Sol-Gel catalyst. The characteristics according to not only the variation of organic and inorganic contents but also the variation of catalyst species and contents were investigated. On the whole, the compatibility was remained between organic and inorganic components, and also as the TEOS contents were increased, mostly the transparency and the mechanical, thermal properties were improved. In addition, as content of catalysts was increased, the films showed characteristics that were closer to PVP than silica. Although the transparency of films was preserved in HCI and CH3COOH, only the film containing more than 40wt% TEOS in NH4OH showed different phenomena.
        4,000원
        78.
        2001.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        LaMnO3, and gel films were deposited by spin-coating technique on scandium-doped zirconia (YSZ) substrate using the precursor solution prepared from , or ,2-methoxyethanol, and polyethylene glycol. By heat-treating the gel films, the electrochemical cells, were fabricated. The effect of polyethylene glycol on the microstructure evolution of and thin films was investigated, and NOx decomposition characteristics of the electrochemical cells were investigated at to . By applying a direct current to the electrochemical cell, good NOx conversion rate could be obtained relatively at low current value even if excess oxygen is included in the reaction gas mixture.
        4,000원
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