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        검색결과 4

        1.
        2017.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the seismic performance of concrete-steel composite moment frame structures equipped with seismic retrofitting systems such as seismic reinforcement, base isolators, and bracing members, which are typical earthquake damage mitigation systems, is evaluated through nonlinear dynamic analyses. A total of five frame models were designed and each frame model was developed for numerical analyses. A total of 80 ground acceleration data were used to perform the nonlinear dynamic analysis to measure ground shear force and roof displacement, and to evaluate the behavioral performance of each frame model by measuring inter-story drift ratios. The analysis results indicate that the retrofitting device of the base isolator make a significant contribution to generating relatively larger absolute displacement than other devices due to flexibility provided to interface between ground and column base. However, the occurrence of the inter-story drift ratio, which is a relative displacement that can detect the damage of the structure, is relatively small compared with other models. On the other hand, the seismic reinforced frame model enhanced with the steel plate at the lower part of the column was found to be the least efficient.
        4,300원
        2.
        2014.12 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to determine the effects of E. coli on boar sperm quality and reproductive performance in sows after artificial insemination. Three different levels of E. coli were artificially inoculated to semen with following concentrations; Control, 500, 5,000 and 50,000 colony forming unit (cfu)/ml. Semen samples were preserved at 17℃ for 5 days. Sperm motility was significantly decreased (p<0.05) on day 3 in the group inoculated with 5,000cfu/ml compared to control groups. In all treatment groups, sperm motility was gradually decreased as storage time increased, but the decline pattern was more drastic in the groups inoculated with 5,000 and 50,000 cfu/ml groups from day 3 (p<0.05) compared to control group. After 3 day of storage at 17℃, sperm viability in sample inoculated with the highest concentration (50,000 cfu/ml) of bacteria was less (p<0.05) than that of control group. The pH of semen sample pH was maintained 7.2~7.5 in all groups during the experimental period. No differences (p>0.05) were found for both storage time and bacterial concentration. The pregnancy rate and live born piglets tend to decrease by increasing the concentration of E. coli in semen. In particular, the rate of pregnancy was lower in the group inoculated with 50,000 cfu/ml (58.3%) compare to the other groups (81.8, 75.0, 76.5%). These results suggest that the contamination of E. coli in boar semen negatively affects fertilizing ability of boar sperm and the reproductive performance obtained from sows after artificial insemination.
        4,000원
        3.
        2014.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study describes the development of innovative connections between steel beams and concrete-filled tube columns that utilize a combination of low-carbon steel and super-elastic shape memory alloy components. The intent is to combine the recentering behavior provided by the shape memory alloys to reduce building damage and residual drift after a major earthquake with the excellent energy dissipation of the low-carbon steel. The analysis and design of structures requires that simple yet accurate models for the connection behavior be developed. The development of a simplified 2D spring connection model for cyclic loads from advanced 3D FE monotonic studies is described. The implementation of those models into non-linear frame analyses indicates hat the recentering systems will provide substantial benefits for smaller earthquakes and superior performance to all-welded moment frames for large earthquakes.
        4,000원
        4.
        2015.11 KCI 등재 서비스 종료(열람 제한)
        The technology of the SWG (Smart Water Grid) as one of most important national projects results in significant assignment that is closely associated with systematic management and effective operation. The individual component technics are required to establish directory and classification for the purpose of effectively managing their information related to research and development (R&D). The national science technology (S&T) standard classification tree which results in the representative example has been established with an intention to manage R&D information, human resource, and budget. It has been also revised every five years and then used in the various fields related to the evaluation, administration, and prediction of the national R&D projects. In addition, the standard classification system for R&D projects has been widely used in the UNESCO (United Nations Educational, Scientific and Cultural Organization) and EU (European Union) since the Frascati Manual was established in the Organization for Economic Cooperation and Development (OECD). Therefore, it is necessary for SWG techniques to develop the standard S&T classification tree for research management and evaluation. For this, it is essential to draw the core techniques for the SWG, which are incorporated with IT (Information Technology), NT (Nano Technology), and BT (Biology Technology).