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        검색결과 32

        21.
        2006.04 구독 인증기관·개인회원 무료
        The linear intercept (LI) method was used to quantitatively measure the intercepts of WC grains in nano-grained WC-10Co hardmetal. When the surveyed intercept numbers of WC grain exceeded 200, the statistic data for the mean grain size of WC were reproduced. The discriminative minimal grain size of used LI method was 12 nm; the maximum intercept of WC grain was 109 nm; the average intercept of WC grains was 45 nm and the corresponding 3D mean grain size of WC was 70 nm which is agreeable with the XRD outcome.
        22.
        2006.04 구독 인증기관·개인회원 무료
        During cold compaction processes loose powder is pressed under tooling action in order to produce complex shaped engineering components. Here, the analysis of the plastic deformation of granular packings is of fundamental importance to the development of computer simulation models. Powders can be idealized by packing discrete particles, where each particle is a sphere meshed with finite elements. The pressing of a body centered cubic packing was compared with numerical prediction and experimental data. The global response was expressed in force-displacement curve, and the accuracy of the numerical models analyzed for high relative densities up to 0.95.
        23.
        2005.06 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        This is to summarize a joint discussion on the future of EAMA in EAMA6. The emphasis was placed on the near future instead of the distant future, Formation of the Working Groups as a means to carry the cooperation for the regions was generally agreed by the attendants of EAMA6 to be the best way toward the establishment of future East Asian Observatory (EAO). Association of Core Observatories (ACO) was proposed to bring resources and foster joint projects for EAMA activities.
        24.
        2004.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A substantial number of processes have been suggested as possible contributors to the extragalactic ɤ-ray background (EGRB). Yet another contribution to this background will be emission produced in hadronic interactions of cosmic-ray protons with the cluster thermal gas; this class of cosmic rays (CRs) has been shown to be responsible for the EUV emission in the Coma Cluster of galaxies. In this paper we assume the CRs in the Coma Cluster is prototypic of all clusters and derive the contribution to the EGRB from all clusters over time. We examine two different possibilities for the scaling of the CR flux with cluster size: the number density of the CRs scale with the number density of the thermal plasma, and alternatively, the energy density of the CRs scale with the energy density of the plasma. We find that in all scenarios the EGRB produced by this process is sufficiently low that it will not be observable in comparison with other mechanisms that are likely to produce an EGRB.
        3,000원
        25.
        2004.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate the role of secondary electrons in galaxy clusters and in ultra-luminous infrared galaxies (ULIGs). The radio emission in galaxy clusters and ULIGs is believed to be produced by the synchrotron radiation of relativistic electrons. Nonetheless, the sources of these relativistic electrons are still unclear. Relativistic secondary electrons can be produced from the hadronic interactions of cosmic-ray nuclei with the intra-cluster media (ICM) of galaxy clusters and the dense molecular clouds of ULIGs. We estimate the contribution of the secondary electrons in galaxy clusters and ULIGs by comparing observational results with theoretical calculations for the radio emission in these sources. We find that the radio halos of galaxy clusters can not be produced from the secondary electrons; on the other hand, at least for some ULIGs, the radio emission can be dominated by the synchrotron emission of the secondary electrons.
        3,000원
        26.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        27.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        In this paper, we present observations of absorption line spectrum of QSO 1225+317 with resolution of 18 km sec-1. Four possible new heavy element line systems are identified. The properties of Lyman α forest lines are discussed.
        28.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        Based on the database of 128 disk galaxies (66 SO, 62 S and Irr) mailnly compiled from Kent and Gunn (1982) and Doi et a1.(1995) which is complete down to m < 15.6 mag within a radius of 3°, the orientation of spin vectors of disk galaxies of the Coma cluster has been analyzed. The results confirm the morphological dependence of the orientation of disk galaxies found from the analsis of the Virgo cluster. Common features of orientation of disk galaxies of both clusters are outlined.
        29.
        1996.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Rings are common in disk galaxies. These rings are either indistinguishable from a pair of tightly wound spirals, or themselves are a part of the spiral structure. Furthermore, their occurrence is seen coincident with a bar in the center. In this paper, we interpret this spiral-ring structure as density waves resonantly excited by a rotating bar potential. The theory gives excellent agreement for the molecular spiral-rings in central parts. of nearby disk galaxies, observed by high resolution radio arrays. The same mechanism works for more distant spiral-rings in the outer parts of disk galaxies qualitatively, although the problem is complicated by the coupling of the stellar and gaseous disks.
        3,000원
        30.
        2020.04 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The study aims to answer why the previous studies find the positive or insignificant effect of the CEO's abilities on firm performance. Using 34,285 CEO-firm-year panel data from the U.S. publicly traded firms drawn from the BoardEx and EXECUXOMP database during from 1992 to 2014, the results show that the fit of the CEO‟s generality or specialist ability with firm strategy matters on firm performance and risk. This study computes a discrete STRATEGY composite measure to construct firm strategy types, such as Prospect or Defend and use CEOs‟ résumés to construct an index of general skills that are transferable across firms and industries. The results find that generalist CEOs are more suitable for prospectors than specialist CEOs. Firm performance is much better when specialist CEOs work for Defenders. Although the firm performance is better too for the generalist CEOs who fit for the Prospect strategy, the firm‟s risk is up too. The result suggests that firms need to consider their chosen business strategy to recruit and select CEOs Our findings provide direct evidence that the match between CEO‟s ability and the firm‟s strategy is crucial to firm performance and risk.
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