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        검색결과 284

        85.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The major limiting factor of the reproductive performance on many farms is the failure to detect estrus in a timely and accurate manner. The estrus detection for Hanwoo cows (Bos taurus coreanea) is generally performed by the visual observation which is estimated at about 40% detection rate only. This recurring problem among farmers has motivated the development of various estrus detection aids. The mounting event duration threshold, standing heat event frequency threshold, estrus detection algorithm and so on, are necessarily needed in order to detect the estrus of Hanwoo cows accurately when using some automatic devices. However, they are not yet investigated for Hanwoo cows. Therefore, the objective of this study was to establish a mounting event duration threshold and standing heat event frequency threshold more specifically for Hanwoo breed by discriminating the duration of standing heat mounting from shorter duration spurious mountings which routinely occur in cattle herds. One hundred and fifty Hanwoo cows with an age between 2 to 5 years were used in this study. Cows that were expected to come into estrus within 3days were randomly assigned to each compartment for the estrus group (EG). The heated cows were video recorded for about 24 hours until after post estrus. The results showed that Hanwoo cows can be considered on estrus when it stand immobile during mounted by any other cow in more than or equal to 3.15s and 3.22s in chest-tail head mount (CTM) and head-above back mount (HBM) and that occurs consecutively at least three times within 876.4s interval. The algorithm was also developed using the thresholds of the mount duration, mount interval and consecutive occurrence number.
        4,000원
        88.
        2014.10 구독 인증기관·개인회원 무료
        95.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        [6]-Gingerol, a major polyphenol of ginger(Zingiber officinale), exhibits a variety ofbiological properties including anti-oxidant, anti-inflammatory and anti-cancer activity. However,the radioprotective effect of [6]-gingerol is still unknown. The aim of this study was to investigatethe radioprotective effect of [6]-gingerol against radiation-induced cell cytotoxicity and oxidativestress in HepG2 cells. [6]-Gingerol pretreatment attenuated radiation-induced cell cytotoxicitycaused by 5Gy(half lethal dose, LD50of HepG2 cells). The measurements of superoxide dismutase(SOD) and catalase(CAT) activity were also performed. The results showed that [6]-gingerol pre-treatment reduced increasing SOD and CAT activity after exposure of IR, indicating that [6]-gin-gerol protected oxidative stress by regulating cellular antioxidant enzyme(SOD and CAT) activity.These findings suggest that [6]-gingerol acts as a radioprotector by attenuating cell cytotoxicityand oxidative stress.
        4,000원
        98.
        2013.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fe-TiC composite was fabricated from Fe and TiC powders by high-energy milling and subsequent spark- plasma sintering. The microstructure, particle size and phase of Fe-TiC composite powders were investigated by field emission scanning electron microscopy and X-ray diffraction to evaluate the effect of milling conditions on the size and distribution of TiC particles in Fe matrix. TiC particle size decreased with milling time. The average TiC particle size of 38 nm was obtained after 60 minutes of milling at 1000 rpm. Prepared Fe-TiC powder mixture was densified by spark- plasma sintering. Sintered Fe-TiC compacts showed a relative density of 91.7~96.2%. The average TiC particle size of 150 nm was observed from the FE-SEM image. The microstructure, densification behavior, Vickers hardness, and frac- ture toughness of Fe-TiC sintered compact were investigated.
        4,000원
        99.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Part 2 of the Questionnaire Survey on Marine Safety and VTS in the Philippine Coastal Waters presents the alternatives to risk reduction, modifying the VTS, the qualification and competency of a VTS operator and effectiveness of the services and assistance rendered by VTS. This study finds that majority of respondents chose "Improved education and training of mariners" as the best alternative to risk reduction and the "Strict enforcement of ship safety regulations" as the best alternative based on the respondents' ranks last served onboard and areas of familiarity. In modifying the VTS, the areas with VTS chose to "Improve or upgrade" and for those without, is to "Implement" the system. The best VTS system is the "Port and Approaches" type and the PCG is selected to operate, maintain and supervise the system. As a VTS operator, the necessity of shipboard experience is considered "Essential" and the experiences include "Ship-handling and Communication", and "Management level" experiences. The effectiveness of the assistance and services rendered by VTS are considered "Very Important". Based on these findings, this study recommends improvement of education and training of mariners and users of the waterways including the training of VTS operators manning the VTS centers, strict enforcement of ship safety regulations along the busy and main ports of the country and installation of VTS system with the most appropriate type with the supervision of PCG.
        4,000원
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