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        검색결과 16

        1.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We report a simple procedure to fabricate single crystals 3D C60 having an FCC structure on silicon substrates using a vapour–solid set-up in vacuum conditions. The morphology of the deposited film can be tuned by controlling the temperature and position of the substrate. The as-fabricated samples are extensively characterised by transmission electron microscopy, scanning electron microscope, X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and nanoindentation, which allow us to shed light on the recrystallization process of the C60. In addition, the growth mechanism of the formation of crystalline 3D structure of the C60 film is discussed in detail. Based on the newly gained knowledge of mechanism and its unique properties, fullerene has shown huge potential as a solid lubricant on various kinds of substrates.
        4,000원
        2.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Titanium dioxide (TiO2) is a typical inorganic material that has an excellent photocatalytic property and a high refractive index. It is used in water/air purifiers, solar cells, white pigments, refractory materials, semiconductors, etc.; its demand is continuously increasing. In this study, anatase and rutile phase titanium dioxide is prepared using hydroxyl and carboxyl; the titanium complex and its mechanism are investigated. As a result of analyzing the phase transition characteristics by a heat treatment temperature using a titanium complex having a hydroxyl group and a carboxyl group, it is confirmed that the material properties were different from each other and that the anatase and rutile phase contents can be controlled. The titanium complexes prepared in this study show different characteristics from the titania-formation temperatures of the known anatase and rutile phases. It is inferred that this is due to the change of electrostatic adsorption behavior due to the complexing function of the oxygen sharing point, which crystals of the TiO6 structure share.
        4,000원
        3.
        2017.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigated a Leidenfrost effect in the growth of ZnO nanostructures on silicon substrates by ultrasonic-assisted spray pyrolysis deposition(SPD). Structural and optical properties of the ZnO nanostructures grown by varying the growth parameters, such as substrate temperature, source concentration, and suction rate of the mist in the chambers, were investigated using field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence spectrum analysis. Structural investigations of the ZnO nanostructures showed abnormal evolution of the morphologies with variation of the substrate temperatures. The shape of the ZnO nanostructures transformed from nanoplate, nanorod, nanopencil, and nanoprism shapes with increasing of the substrate temperature from 250 to 450 °C; these shapes were significantly different from those seen for the conventional growth mechanisms in SPD. The observed growth behavior showed that a Leidenfrost effect dominantly affected the growth mechanism of the ZnO nanostructures.
        4,000원
        4.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Bi2Te3 powders are recovered by wet chemical reduction for waste n-type thermoelectric chips, and the recovered particles with different morphologies are prepared using various surfactants such as cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), and ethylenediaminetetraacetic acid (EDTA). When citric acid is added as the surfactant, the shape of the aggregated particles shows no distinctive features. On the other hand, rod-shaped particles are formed in the sample with CTAB, and sheet-like particles are synthesized with the addition of SDBS. Further, particles with a tripod shape are observed when EDTA is added as the surfactant. The growth mechanism of the particle shapes depending on the surfactant is investigated, with a focus on the nucleation and growth phenomena. These results help to elucidate the intrinsic formation mechanism of the rod, plate, and tripod structures of the Bi2Te3 recovered by the wet reduction process.
        4,000원
        5.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the main growth mechanism of InP during InP/ZnS reaction of quantum dots (QDs). The size of the InP core, considering a synthesis time of 1-30 min, increased from the initial 2.56 nm to 3.97 nm. As a result of applying the proposed particle growth model, the migration mechanism, with time index 7, was found to be the main reaction. In addition, after the removal of unreacted In and P precursors from bath, further InP growth (of up to 4.19 nm (5%)), was observed when ZnS was added. The full width at half maximum (FWHM) of the synthesized InP/ZnS quantum dots was found to be relatively uniform, measuring about 59 nm. However, kinetic growth mechanism provides limited information for InP / ZnS core shell QDs, because the surface state of InP changes with reaction time. Further study is necessary, in order to clearly determine the kinetic growth mechanism of InP / ZnS core shell QDs.
        4,000원
        6.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was determined the hair growth effect and mode of action of a complex extract (abelmo), extracted from various natural plants including Acorus calamus var. angustatus. 30 six-week old C57BL/6 mice were randomly assigned into three treatment groups with ten mice per treatment group repeatedly. The treatment group is a control group, and was classified into saline-applied, minoxidil 5%-applied, and abelmo-applied groups. Hair growth started from the abelmo-applied and minoxidil 5% -applied groups on the 9th day, compared to the saline-applied group. Hair growth rate was 17.06% and 19.15% in those two groups, respectively, and the abelmo-applied group's hair growth rate was higher. The density, length and thickness of hair were significantly higher in the order of abelmo-applied group, minoxidil 5%-applied group and saline-applied group on the 9th day, and hair root was strongly maintained in the abelmo-applied group. The density, length and thickness of hair in the abelmo-applied group were significantly higher by 599.8, 122.2 and 181.8% on the 9th day compared to the saline-applied group, and 166.7, 171.4 and 200.2% on the 12th day, and 136.6, 216.9 and 180.7%, respectively on the 15th day. As for hair follicle and the length of hair shaft from the dosal skin histopathology manifestation, the abelmo-applied group was more excellent than the saline-applied group and minoxidil 5%-applied group. This result actually confirmed the fact that abelmo promotes hair growth and strongly maintains hair root simultaneously.
        4,000원
        7.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, we report in-situ observations of changes in catalyst morphology, and of growth termination of individual carbon nanotubes (CNTs), by complete loss of the catalyst particle attached to it. The observations strongly support the growth-termination mechanism of CNT forests or carpets by dynamic morphological evolution of catalyst particles induced by Ostwald ripening, and sub-surface diffusion. We show that in the tip-growth mode, as well as in the base-growth mode, the growth termination of CNT by dissolution of catalyst particles is plausible. This may allow the growth termination mechanism by evolution of catalyst morphology to be applicable to not only CNT forest growth, but also to other growth methods (for example, floating-catalyst chemical vapor deposition), which do not use any supporting layer or substrate beneath a catalyst layer.
        4,000원
        8.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Amino acid transporters are essential for the growth and proliferation in all living cells. Among the amino acid transporters, the system L amino acid transporters are the major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The L-type amino acid transporter 1 (LAT1), an isoform of system L amino acid transporter, is highly expressed in cancer cells to support their continuous growth and proliferation. 2-Aminobicyclo-(2,2,1)-heptane-2-carboxylic acid(BCH) is a model compound for study of amino acid transporter as a system L selective inhibitor. We have examined the effect and mechanism of BCH on cell growth suppression in FaDu human head and neck squamous cell carcinoma. The BCH inhibited the L-leucine transport in a concentration-dependent manner with a IC 50 value of 43.8±4.3μM. The majority of L-leucine uptake is, therefore, mediated by LAT1 in FaDu cells. The growth of FaDu cells was inhibited by BCH in the time- and concentration- dependent manners. The formation of DNA ladder was not observed with BCH treatment in the cells. Furthermore, the proteolytic processing of caspase-3 and caspase-7 in the cells was not detected by BCH treatment. These results suggest that the BCH inhibits the growth of FaDu human head and neck squamous cell carcinoma through the intracellular depletion of neutral amino acids for cell growth without apoptotic processing
        4,000원
        9.
        2006.04 구독 인증기관·개인회원 무료
        Calcium-hexaluminate phase is known to be effective for the crack shielding due to the spinel block crystal structure. In this study, we focused to the control of morphology for good damage tolerance behavior in alumina and zirconia/calcium-hexaluminate composites. Calcium-hexaluminate composites were prepared from zirconia, alumina and calcium carbornate powders. Calcium-hexaluminate phase was obtained by the solid reaction through the formation of intermediate phase . phase showed the column type abnormal grain grown behavior composed of small blocks. Due to the typical microstructure of , alumina and zirconia/calcium-hexaluminate composites provide a well controlled crack propagation behavior.
        10.
        2006.04 구독 인증기관·개인회원 무료
        Magnetic oxide-coated iron nanoparticles with the mean size ranging from 6 to 75 nm were synthesized by aerosol method using iron carbonyl as a precursor under the flowing inert gas atmosphere. Oxide shells were formed by passivation of asprepared iron particles. The influence of experimental parameters on the nanoparticles' microstructure, phase composition and growth behavior as well as magnetic properties were investigated and discussed in this study.
        13.
        2001.06 구독 인증기관·개인회원 무료
        WC-Co 계의 입성장 억제는 현재 초경합금 분야에서 공학적으로 가장 중요한 이슈들 중의 하나이다 VC를 비롯한 입방정 탄화물이나 등의 여러 가지 탄화 물이 혼합되어 입성장 억제에 이용되는데 입성장 억제의 효과는 대략적으로 용해되는 탄화물의 양에 의존하고 있는 것으로 추정된다. 보다 효율적으로 입성장 억제를 실현하려면 입성장 기구를 명확히 할 필요가 있다. 최 등[1]은 VC가 WC 입자 표면 에서의 edge energy를 증가시켜서 2차원 핵생성의
        14.
        2000.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The property and performance of the nanocomposites have been known to strongly depend on the structural feature of Ni nanodispersoids which affects considerably the structure of matrix. Such nanodispersoids undergo structural evolution in the process of consolidation. Thus, it is very important to understand the microstructural development of Ni nanodispersoids depending on the structure change of the matrix by consolidation. The present investigation has focused on the growth mechanism of Ni nanodispersoids in the initial stage of sintering. powder mixtures were prepared by wet ball milling and hydrogen reduction of and Ni oxide powders. Microstructural development and the growth mechanism of Ni dispersion during isothermal sintering were investigated depending on the porosity and structure of powder compacts. The growth mechanism of Ni was discussed based upon the reported kinetic mechanisms. It is found that the growth mechanism is closely related to the structural change of the compacts that affect material transport for coarsening. The result revealed that with decreasing porosity by consolidation the growth mechanism of Ni nanoparticles is changed from the migration-coalescence process to the interparticle transport mechanism.
        4,000원