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        검색결과 4

        1.
        2016.06 구독 인증기관·개인회원 무료
        Ganoderma lucidum, a species of the class Basidiomycetes, attracts international attention due to the wide variety of its biological activities and great potential as cosmetic ingredient, such as skin care cosmetics including ‘skin-whitening’. However, there is little information available regarding the tyrosinase inhibitory activity. Therefore, the objectives of this study were to investigate the chemical composition and tyrosinase inhibitory activity of the G. lucidum. To isolate active single compound from G. lucidum (GASC), we conducted ethanol extraction and chloroform fractionation. In addition, we assayed the inhibitoty effect of tyrosinase activity and melanin biosynthesis in B16F10 mouse melanoma cells. In the present study, we identified a GASC, which exhibited inhibitory effects of cellular tyrosinase activity, the protein expression of cellular tyrosinase and tyrosinase-related protein-1, 2. In additional, microphthalmia-associated transcription factor (MITF), as known as crucial regulator of melanogenesis-related genes, was down-regulated by treatment with GASC in a concentration-dependent manner. GASC exhibited significant inhibition of tyrosinase activity and melanin synthesis in B16F10. The finding that melanogenesis inhibitory effect of GASC will contribute to facilitate various approaches of this mushroom for use in skin whitening products.
        2.
        2014.04 구독 인증기관·개인회원 무료
        This study mainly treats a new type of the bracing friction damper system, which is able to minimize structural damage under earthquake loads. The slotted bolt holes are placed on the shear faying surfaces with an intention to dissipate considerable amount of friction energy. The superelastic shape memory alloy (SMA) wire strands are installed crossly between two plates for the purpose of enhancing recentering force that are able to reduce permanent deformation occurring at the friction damper system. The smart recentering friction damper system proposed in this study can be expected to reduce repair cost as compared to the conventional damper system because the proposed system mitigates the inter-story drift of the entire frame structure. The response mechanism of the proposed damper system is firstly investigated in this study, and then numerical analyses are performed on the component spring models calibrated to the experimental results. Based on the numerical analysis results, the seismic performance of the recentering friction damper system with respect to recentering capability and energy dissipation are investigated before suggesting optimal design methodology. Finally, nonlinear dynamic analyses are conducted by using the frame models designed with the proposed damper systems so as to verify superior performance to the existing damper systems.
        4.
        2003.06 KCI 등재 서비스 종료(열람 제한)
        This study compared the levels of North Dakota and South Korean conventional and sustainable farmers’ participation in community organizations. The North Dakota data were collected in 1990 from a sample of 568 farm and ranch operators, and the South Korean data were collected in late 1999 and early 2000 from a sample of 147 farmers through interviews and surveys. The data were analyzed using the SPSS ANOVA computer program. The sustainable farmers in both countries were more likely to participate in community organizations than the conventional farmers. Nevertheless, through this comparative study it was found that some differences between two countries exist due to their different cultural backgrounds. Whereas Americans were oriented more to morality and ethics influenced by church, farmers in Korean were more influenced by civil movements. Whereas the reduced tillage farmers in Americans were more likely to be sustainable farmers, the mixed farmers in Korea were more likely to belong to conventional farmers. While individuals in community organizations focused on the economics of agriculture, sustainable farming and farmers" social participation were social matters, which were used to develop sustainable community.