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        검색결과 6

        4.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out in the peatland for estimating the paleoenvironment based on the analysis from its fossils plant and radiocarbon at the Hwayang-ri, Hyeondeok-myeon, Pyeongtaek-city, South Korea. Variety of fossil was collected from the peatland which could discriminated with naked eye and sorted into seeds, leaves, stems from four-stage of standard sieve. During analysis for the large plant fossil within the peatland, the dead plants were largely divided into 3 fossil zones according to its peatland. In the fossil zone Ⅲ(the oldest layer; 6,970~6,070 yr C14 B.P.), the observation of leaves of hydrophyte such as Trapa sp. and stems of Alnus japonica which appeared in wetland means that the environment was influenced by the climate changes such as rainfall increasing and sea level rise. In the fossil zone Ⅱ(the middle layer; 6,070~5,800 yr C14 B.P.), the occurrence of Gramineae, Cyperaceae and Fagaceae indicate that the environmental condition might be more or less dry by decreasing rainfall and drop in sea level. The fossil zone Ⅰ(the recent layer; 5,800~4,540 yr C14 B.P.) where lots of herbaceous plants, increasing of Fagaceae, decreasing of A. japonica. and distribution of Pinaceae were showed, was inferred to be repeated both dry and wet environment due to human disturbance.
        4,000원
        5.
        2006.09 구독 인증기관·개인회원 무료
        Cube textured Ni substrate were fabricated for YBCO coated conductors from the initial specimens prepared by powder metallurgy (P/M) and casting and the effects of annealing temperature and reduction ratio on texture formation and microstructural evolution were evaluated. The initial specimens were rolled and then annealed in the temperature at . A strong cube texture formed for P/M substrate, and the degree of texture did not significantly vary with annealing temperature of . On the other hand, the texture of casting substrate was more dependent on the annealing temperature and twin texture and several minor texture components started to form at .
        6.
        2006.09 구독 인증기관·개인회원 무료
        We fabricated Bi-2212/ composite superconductors and evaluated the effects of the powder mixing method and melting temperature on their microstructure and superconducting properties. The Bi-2212 powders were mixed with by hand-mixing (HM) and planetary ball milling (PBM) and then the powder mixtures were melted at , solidified, and annealed. We found that the powder mixture prepared by PBM was finer and more homogeneously mixed than that prepared by HM, resulting in more homogeneous microstructure and smaller and second phases after annealing.