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        검색결과 757

        161.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We measured the non-carbon content of single-walled carbon nanotubes (SWCNTs) in SWCNT soot using thermogravimetric analysis. The weight increased percentage by the oxidation of metal in the raw soot is well obtained by TGA graph which was confirmed with ICP-AES, XRD, and XPS. This work will be very useful for the purity precise evaluation of SWCNT with UN-vis-NIR spectroscopy.
        3,000원
        162.
        2008.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Recently, Choe & Cheng (2002) have demonstrated that multiple magnetic flux systems with closed configurations can have more magnetic energy than the corresponding open magnetic fields. In relation to this issue, we have addressed two questions: (1) how much fraction of eruptive solar active regions shows multiple flux system features, and (2) what winding angle could be an eruption threshold. For this investigation, we have taken a sample of 105 front-side halo CMEs, which occurred from 1996 to 2001, and whose source regions were located near the disk center, for which magnetic polarities in SOHO/MDI magnetograms are clearly discernible. Examining their soft X-ray images taken by Yohkoh SXT in pre-eruption stages, we have classified these events into two groups: multiple flux system events and single flux system events. It is found that 74% (78/105) of the sample events show multiple flux system features. Comparing the field configuration of an active region with a numerical model, we have also found that the winding angle of the eruptive flux system is slightly above 1.5π.
        4,000원
        163.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effects of type of the sugar supplemented to the extender on the vigor, viability and intact acrosomal rates of frozen-thawed dog spermatozoa. The ejaculated semen was diluted with TRIS-citric acid extender containing 200mM TRIS, 73mM citric acid, 6% (v/v) glycerol, 20% (v/v) egg yolk, 1% (v/v) antibiotics (streptomycin/penicillin), 44 mM sugar, which was either glucose, fructose or glucose-fructose combination, and distilled water to make the final volume of 100ml. Extended semen samples were cooled at for an hour, packaged in 0.25ml straws, equilibrated for 10 minutes in liquid nitrogen vapor, and frozen in liquid nitrogen. Samples were thawed by placing straws into water for 120 seconds. After thawing, vigor, viability and intact acrosomal rates of frozen-thawed semen were compared according to type of sugar. No significant differences were observed between glucose and fructose groups. In addition, combination of the 2 sugars also did not show any significant differences in the vigor, viability and intact acrosomal rates. In conclusion, glucose and fructose were equally efficient as sugar supplements for freezing extender.
        4,000원