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        검색결과 15

        7.
        2018.05 구독 인증기관·개인회원 무료
        Roller Compacted Concrete Pavement (RCCP) is placed by roller compaction of a mixture of less cement and unit water content and more aggregates and provides excellent early strength development with the help of interlocking of aggregates and hydration. The unit cement content of RCC pavements accounts for 85% of conventional pavements, with low drying shrinkage. As low drying shrinkage leads to smaller crack widths than ordinary concrete, RCC pavements can help elevate reflecting crack resistance if applied to a base layer of a composite pavement system. In a composite pavement with an asphalt surface laid over a concrete base, pavement temperature change is important in predicting pavement performance. As movement of the lower concrete layer is determined by temperature depending on pavement depth, temperature data of the pavement structure serves as an important parameter to prevent and control reflecting crack. Among the causes of reflecting crack, horizontal behavior of the lower concrete layer and curling-caused vertical behavior of joints/cracks are considered closely related to temperature change characteristics of the lower concrete course (Baek, 2010). Previous studies at home and abroad about reflecting crack have focused on pavement behavior depending on daily and yearly in-service temperature changes of a composite pavement (Manuel, 2005). Until now, however, studies have not been conducted on initial temperature characteristics of concrete in composite pavements where asphalt surface is placed over an RCC base. Annual temperature changes of in-service concrete pavements go up to 60 ℃, and those of asphalt overlays become around the twice at 110 ℃. This study evaluated initial crack behavior of composite pavement by investigating pavement temperature by depth of an RCC base and analyzing joint movement depending on change to temperatures of continuously jointed pavements. Findings from the study suggest that in composite pavements and asphalt overlays, time of laying asphalt has an important impact on crack behavior and reflecting crack.
        11.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research tested how the perceived risk and the trust affect the usage intention of the cloud computing. To this end, this research setups a research model and tests it with the statistic tools. In order to build the model, TAM (Technology Acceptance
        4,000원
        12.
        2012.06 구독 인증기관·개인회원 무료
        True hermaphrodites are animals of equivocal sex in which both male and female gonads develop simultaneously. The frequency of true hermaphroditism is higher in pigs than in other domestic animals. Two Korean pigs were diagnosed with true hermaphroditism showing ovotestes, epididymes, penes, and uteri. Histomorphologically, the testicular tissues consisted of Sertoli cells that were devoid of spermatogenic germ cells and showed proliferation of interstitial cells. However, the uteri were of normal architecture and had well-developed uterine endometrial glands. The samples were 38, XX female karyotype without the sex-determining region Y (SRY) gene. The findings of this study could contribute to the understanding of true hermaphroditism in the Korean pig industry. * This work was supported by a grant (Code# PJ008148) from BioGreen21 Program, Rural Development Administration, Republic of Korea.
        13.
        2010.12 KCI 등재 구독 인증기관·개인회원 무료
        Recently, farmers of mushroom farms in Korea express the difficulty of shiitake cultivation due to the damage of oak log beds by unknown reason. To elucidate the cause of the damage, we investigated and isolated fungi from inside wood chip of the damaged shiitake log bed. Four of green fungi were obtained and their morphology and molecular properties examined. Trichoderma atroviride, Trichoderma citrinoviride, Hypocrea lixii (Trichoderma harzianum), and Hypocrea lutea (Gliocladiumviride) were identified. Hypocarea lutea is newly described in Korea. These species were able to produce extracellular enzymes such as cellulase, pectinase, and xylanse that might degrade wood components of oak logs. This study provides strong evidence that Trichoderma fungi are involved in the recent damages of shiitake log beds In Korea.
        15.
        2016.10 서비스 종료(열람 제한)
        Background : Haskap berries commonly refer to fruits of Lonicera caerulea L., recognized by the Japanese aborigines as the “The elixir of life.”. Due to their recent arrival on the North American market, haskap berries have not yet been positioned among other berries and compared in terms of their phytochemical content. And haskap berries have higher ascorbic acid and anthocyanin content than other berries known for their health-promoting benefits, such as blueberries. However, no study has reported on the antioxidant and anti-cancer activity of Lonicera caerulea stem. The purpose of this study is to present the current research on the chemical content, antioxidant and anti-cancer activities of Lonicera caerulea stem. Methods and Results : The stem of Lonicera caerulea L. ware dried in the shade at room temperature and extracted with 100% methanol. The extract was suspended in deionized water and partitioned sequentially with n-hexane, chloroform, ethyl-acetate and butanol (water saturated BuOH) fractions. Antioxidant activities were measured by determination of antioxidants, DPPH (2,2-diphenyl-1-picrylhydrazyl). Cell viability was determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. All cell lines were purchased from the Korean Cell Line Bank (Seoul, Korea). All results were performed with three replications were processed statistically. By DPPH assay, the Lonicera caerulea L. the highest activity was obtained from the ethyl-acetate fraction (IC50=15.46 ㎍/㎖). By MTT assay, the chloroform fraction showed a significant growth inhibiting effect on MCF-7 (Human breast cancer, IC50=225.91 ㎍/㎖), COLO 205 (Human colon cancer, IC50=179.55 ㎍/㎖), but on AGS (Human stomach cancer) and other fractions it did not show effect. Conclusion : We demonstrated that Lonicera caerulea L. stem extract and fractions has antioxidant and antiproliferation activity in vitro. Further studies should identify the active constituents in Lonicera caerulea L stem to evaluate the potential in vitro antioxidant and antiproliferation activities of the extract.