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        검색결과 64

        42.
        2001.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have studied the central parts of M82, which is a well-known infrared luminous, starburst galaxy, by analyzing archival data from the Infrared Space Observatory (ISO). M82 was observed at 11 positions covering ±45" from the center along the major axis. We analyzed 4 emission lines, [ArIII] 8.99 μm, H2 17.034 μm, [FeII] 25,98 μm, and [SiII] 34,815 μm from SWSO2 data. The integrated flux distributions of these lines are quite different. The H2 line shows symmetric twin peaks at ~18" from the center, which is a general characteristic of molecular lines in starburst or barred galaxies. This line appears to be associated with the rotating molecular ring at around ~200 pc just outside the inner spiral arm. The relative depletion of the H2 line at the center may be due to the active star formation activity which dissociates the H2 molecules. The other lines have peaks at the center and the distributions are nearly symmetric. The line profiles are deconvolved assuming that both intrinsic and instrumental profiles are Gaussian. The velocity dispersion outside the core is found to be ~50 km s-1. The central velocity dispersion is much higher than 50 km s-1, and different lines give different values. The large central velocity dispersion (σ) is mostly due to the rotation, but there is also evidence for a high σ for [ArIII] line. We also generated position-velocity maps for these four lines. We found very diverse features from these maps.
        4,000원
        45.
        2000.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Raman spectroscopy has been used to investigate the structure of coal tar pitch heat-treated up to 3000℃ by using 514.5 run Ar ion laser line. Four critical temperature ranges were found on pyrolyzing coal tar pitch, which correspond to four distinct processes from disordered carbons to the well-ordered graphite structure. The range of heat treat temperature (HTT) below 1000℃ corresponds to gas evolution during the pyrolysis of coal tar pitch. Above the HTT are correlated to rearrangements of enlarged molecules, growth of the molecules along the direction of plane, finally stacking in the normal direction of the plane, in the respective HTT ranges of 1000-2000, above 2000 and 2500-3000℃.
        4,000원
        46.
        1999.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Open clusters are useful tools to investigate the structure and evolution of the Galactic disk. We have started a long-term project to obtain UBVI CCD photometry of open clusters which were little studied before, using the Doyak 1.8 m telescope of Bohyunsan Optical Astronomy Observatory in Korea. The primary goals of this project are (1) to make a catalog of UBVI photometry of open clusters, (2) to make an atlas of open clusters, and (3) to survey and monitor variable stars in open clusters. Here we describe this project and report the first results based on preliminary analysis of the data on four open clusters in the survey sample: Be 14, Cr 74, Biu 9, and NGC 2355. Isochrone fitting of the color-magnitude diagrams of the clusters shows that all of them are intermediate age to old (0.3-1.6 Gyrs) open clusters with moderate metallicity.
        4,000원
        49.
        1996.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have studied the response of molecular clouds in the Galactic disk to a rotating bar by conducting Smoothed Particle Hydrodynamics (SPH) simulations for the Galaxy in order to understand the dynamical structures of the Galactic Center (GC) molecular clouds, and their implications. In our study it was found that the structures of GC molecular clouds could be induced by the combined effects of rotating bar potential, the hydrodynamic collisions and gravitational miss collisions between the clouds.
        3,000원
        52.
        1992.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Effects of cloud rotation 011 the profiles of CO J= 1 → 0 lines arc investigated by theoretically general ing line profiles under physical conditions similar to t he ones in large globules. The synthesized profiles are presented and their characteristics are discussed. It is found that when the Doppler shift of the observed CO lines is interpreted as the rotation velocity, the optically thin 13 C O lines underestimate the rotation velocity by up to 10 percents, while the self-reversed optically thick 12 C O lines overestimate the velocity up to 20 percents. The optically thin line is shown to be of use in probing the distribution of rotation velocity in dark globules.
        4,600원
        53.
        1991.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Infrared emission maps are constructed at 12.5, 25, 60, and 100 μ m for dark globules B5, B34, B133, B134, B361, L134 and L1523 by using Infrared Astronomical Satellite data base. These clouds are selected on the basis of their appearance in Palomar print as dark obscuring objects with angular sizes in the range of 3 to 30 arcminutes. The short wavelength(12.5 and 25 μ m ) maps show the embedded infrared sources. We found many such sources only in B5, B361 and B34 regions, Diffuse component at 12.5 and 25 μ m , possibly arising from the stochastically heated very small dust grains(a < 0.01 μ m ) by interstellar radiation field, is found in B361 and L1523 regions. Such emission is characterized by the limb brightening, and it is confirmed in L1523 and in B361. Infrared emissions at the long wavelengths(60 and 100 μ m ) are due to colder dusts with temperature less than 20 K. The distribution of color index determined by the ratio 60 to 100 μ m intensities shows monotonic decrease of dust temperature toward the center. The black body temperature determined from these ratios is found to lie between 16 and 23 K. Such temperature is possible for small(i.e., a ≲ 0.01 μ m ) graphite grains if the grains are mainly heated by interstellar radiation field. Thus IRAS 100 and 60 μ m emissions are arising mainly from small grains in the colud. The distribution of such dust grains implied from the emissivity distributions at 100 and 60 μ m resembles that of isothermal sphere. This contrasts to earlier findings of much steeper distribution of dusts contributing visible extinction. These dust grains are mainly larger ones(i.e., a ≃ 0.1 μ m ). Therefore we conclude that the average grain size increase, toward the cloud center.
        4,900원
        54.
        1981.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Theoretical profiles of selected rotational lines of C 2 CH, CN, TiO and MgH are computed by using the current models of sunspot unbrae and penumbrae. It is found that the lines of the diatomic carbides are enhanced in penumbrae relative to umbrae, while MgH lines are more strongly enhanced in umbrae than in penumbrae and the quiet photosphere. The results are discussed with respect to selecting lines suitable for studying the structure of sunspots.
        4,000원
        55.
        1981.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Calculations of molecular number densities as a function of optical depth in selected umbral, penumbral and photospheric models predict penumbral enhancement of diatomic molecules containing carbon atoms, strong umbral enhancement of oxides, and moderate umbral enhancement of hydrides. The role of CO formation in an oxygen rich atmosphere is discussed.
        5,100원
        56.
        1980.12 구독 인증기관·개인회원 무료
        57.
        2011.12 KCI 등재 서비스 종료(열람 제한)
        Construction of the Asian Network for Sustainable Organic Farming Technology (ANSOFT) will be cooperatively administered by the public researchers in 12 Asian member countries from 2010 to 2012. ANSOFT will bring forward multiple reports, which will be constantly renewed by the member countries, regarding environmental issues, plant and landscape protection techniques, regulations and policies of each country’s government on an organic ag끼culture, and natural resources such as organic seeds and biological agents.
        58.
        2010.09 서비스 종료(열람 제한)
        Controllable transgenic expression systems in transgenic animal model are valuable to the development of therapeutic approaches in human medical fields. The aim of this study was to 1) produce a transgenic cloned dog using inducible tetracycline vector system, and 2) investigate whether the transgenic cloned dog could be induced the transgene expression using doxycycline (Doxy). Canine fetal fibroblasts were infected with retroviral vectors designed to express the enhanced green fluorescent protein (eGFP) gene under the control of tetracycline-inducible promoter. For somatic cell nuclear transfer (SCNT), nucleus of an in vivo matured oocyte was removed and an eGFP expressed cell cultured with 1 ㎍/㎖ of Doxy was injected. After electrical fusion and chemical activation, the reconstructed embryos were transferred to a recipient and pregnancy diagnosis was performed by ultrasonography. Experiment I evaluated the mean fluorescence intensity (MFI) of infected cells while the cells were cultured in the presence of 1 ㎍/㎖ of Doxy for 5 days, and then in the absence of Doxy for 7 days using fluorescence-activated cell sorter. Experiment II was designed to produce an eGFP controllable transgenic cloned dog via SCNT. For verification of transgenic dog, experiment III was performed Southern Blot analysis and observation in vivo regulation of eGFP expression in the cloned dog treated with 100 ㎎/㎏ of Doxy every 2 days for 2 weeks under ultraviolet light. In experiment IV, western blot was used to detect eGFP increase and decrease in skin tissues of transgenic dog under the presence or absence of Doxy. In the results of experiment I, the MFI for infected cells was rapidly increased to approximately 42.3 times after 3 day-treatment compared to pre-treatment and quickly decreased 3 days after ceasing the treatment. In experiment II, a total of 203 embryos were transferred to nine recipients and three pregnant delivered three pups (Tet-on eGFP 0, Tet-on eGFP 1, and Tet-on eGFP 2) by C-sec and Tet-on eGFP 2 among them is still alive. All cloned pups were genetically identical to the donor cell. Tet-on eGFP 2 showed an apparent in vivo eGFP expression on her body after Doxy administration in experiment III. The result of Sothern blotting showed that the transgene insertion was detected from the three cloned dogs and all organs of Tet-on eGFP 1. Experiment IV indicated that a robust eGFP expression in skin tissue of Tet-on eGFP 2 rapidly increased after Doxy treatment and gradually decreased to basal level on 9 weeks after ceasing the treatment. In conclusion, we report here for the first time an inducible transgenic system in canine species and it can stably induce the transgene expression at intended time. This study has demonstrated the capacity to generate transgenic model dog which could regulate the transgene and it would contribute to human medical research fields.
        59.
        2009.03 KCI 등재 서비스 종료(열람 제한)
        "Early Valley", is an early maturing potato cultivar with high yield potential. "Early Valley" is a clonal selection resulting from the cross between 'Suncrisp' and 'A87109-10'. It has medium plant height and light green foliage. "Early Valley" has medium flowering habit and white flowers. Tubers are smooth, yellow skin, light yellow flesh, round tuber shape, medium eye depth, and medium dormancy and good keeping quality. It has stable yield under wide range of climatic conditions. "Early Valley" is resistance to late blight, but moderately susceptible to common scab and hollow heart. This cultivar is also resistant to potato rotting at harvesting during the raining season. "Early Valley" has high level of antioxidant activity (about three times higher) and vitamin C (higher by 40%) than the 'Superior'. This cultivar has high level of tuber uniformity and capable of yielding 36.56 t/ha which is 17.07% higher than the control potato cultivar 'Superior' under optimum agronomical practices.
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