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        검색결과 96

        62.
        2005.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Isotopes of alkali and alkaline earth metals (AM and AEM) are the main contributors to the heat load and the radiotoxicity of spent fuel (SF) . These components are separated from the SF and dissolved in a molten LiCl in an electrolytic reduction process. A mass transfer model is developed to describe the diffusion behavior of Cs, Sr, and Ba in the SF into the molten salt. The model is an analytical solution of Fick's second law of diffusion for a cylinder which is the shape of a cathode in the electrolytic reduction process. And the model is also applied to depict the concentration profile of the oxygen ion which is produced by the electrolysis of LiO. The regressed diffusion coefficients of the model correlating the experimentally measured data are evaluated to be greater in the order of Ba, Cs, and Sr for the metal ions and the diffusion of the oxygen ion is slower than the metal ions which implies that different mechanisms govern the diffusion of the metal ions and the oxygen ions in a molten LiCl.
        4,000원
        68.
        2004.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        FePt nanoparticles for high-density magnetic recording media were synthesized by the simultaneous chemical reduction of Fe(acac) and Pt(acac) with 1,2-hexadecanediol as the reducing reagent. TEM images showed that the shape of as-synthesized FePt nanoparticle was spherical and average particle size was 3 nm. Also, SAD pattern showed that crystal structure was disordered FCC (face centered cubic). These FCC structured nanoparticles were transformed FCT (face centered tetragonal) structure by annealing at 55 for 30 min in Ar atmosphere. XRD analysis revealed that as-synthesized FePt nanoparticles were transformed from disordered FCC to ordered FCT. Finally, the coercivity of 2 kOe for FePt nanoparticles with FCT structure was obtained by VSM measurement.
        4,000원
        71.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The magnetic Nd-Fe-B powders were prepared by a thermochemical method, consisting of the processes of spray-drying, debinding, milling, H-reduction, Ca-reduction, and washing. The optimum process conditions were studied by microstructural and thermal analysis. The resultant Nd-Fe-B powder was spherical with the size of 1 . Effects of the process parameters of each step on the microstructure of the powders were investigated, and their magnetic properties were evaluated
        4,000원
        72.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ultra fine titanium carbide particles were synthesized by novel metallic thermo-reduction process. The vaporized TiC1+ gases were reacted with liquid magnesium and the fine titanium carbide particles were then produced by combining the released titanium and carbon atoms. The vacuum treatment was followed to remove the residual phases of MgC1 and excess Mg. The stoichiometry, microstructure, fixed and carbon contents and lattice parameter were investigated in titanium carbide powders produced in various reaction parameters.
        4,000원
        80.
        2002.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The efects of mechanical aloying conditions and the type of reducing agent on the solid state reductionof haematite have been investigated at room temperature. Aluminium titanium zinc and copper were used as reducing agent. Nanocomposites of metal-oxide in which oxide particles with nano size were dispersed in Fe matrix were obtained by mechanical alloying of with aluminium and titanium respectively However the reduction of by coppe was not occurred Composite materials of iron with and were obtained from the system of and after ball milling for 20 hrs and 30 hrs respectively. And the system of resulted in the formationof FeO with ZnO after ball milling of 120 hrs. The final grain sizes of iron estimated by X-ray diffraction line-width measurement were in the ranges of 24~33 nm.
        4,000원
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