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        검색결과 8

        1.
        2016.10 서비스 종료(열람 제한)
        Background : Astilboides tabularis (Hemsl.) Engl. is a perennial herbaceous plant, distributed in the northern high mountains of the Korean peninsula and China. It is an excellent ornamental plant currently at risk of overharvesting and therefore, is designated as an endangered wild plant Class II by the Ministry of Environment. Physiological research on A. tabularis has not be reported. Therefore, in this study, using A. tabulari extracts, antioxidant and Anti-inflammatory effects were determined. Methods and Results : The antioxidant and free radical scavenging activities of A. tabularis extracts were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The results showed that the ethyl acetate fraction of A. tabularis possesses potent DPPH radical scavenging activity (2.90±0.08㎍/㎖), similar to the scavenging activity of ascorbic acid (2.19±0.06㎍/㎖), and better than the powerful antioxidant α-tocopherol (10.60±0.40㎍/㎖) as well as BHA (butylatedhydroxy anisole)(6.12±0.27㎍/㎖). The ethyl acetate fraction possessed a significantly higher concentration of total phenolic (549.70±2.72㎎GAE/g) and flavonolic content (154.58±1.04㎎QE/g). It was also found that the ethyl acetate fraction exhibited high reducing power and inhibition of ROS (Reactive Oxygen Species) formation. Different fractions of A. tabularis were tested for anti-inflammatory activity using LPS stimulated Raw 264.7 cells. The n-hexane and ethyl acetate fractions exhibited a high inhibitory effect on NO (Nitrite oxide) production (22.43±1.06%, 19.30±0.45%, respectively) at 200㎍/㎖ concentration. The mRNA of IL-1β, iNOS and COX-2 gene expression was decreased by treatment with the ethyl acetate fraction. These results showed that A. tabularis extracts can be used as natural substances to control inflammation. Conclusion : These result showed that A. tabularis extracts can be used in a variety of antioxidant and other functional product research and development processes as valuable natural materials.
        2.
        2012.12 KCI 등재 서비스 종료(열람 제한)
        Recently, tug boats are widely used for towing a barge which transports building materials, a large block of a ship, offshore crane, and so on. In order to simulate the dynamics of the coupled towing system correctly, the dynamics of the towline should be well modeled. In this paper, the towline was modeled as the multiple finite elements, and each element was assumed as a rigid cylinder which moves in five degrees of freedom except roll. The external tension and its moment acting on each element of the towline were modeled depending on the position vector's direction. Tugboat's motion was simulated in six degrees of freedom where wave and current effects were included, and towed barge was assumed to move in the horizontal plane only. In order to confirm the mathematical models of the coupled towing systems, standard maneuvering trials such as course changing maneuver, turning circle test and zig-zag test were simulated. In addition, the same trials were simulated when the external disturbances like wave and current exist. As the result, it is supposed that the results might be qualitatively reasonable.