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        검색결과 2,998

        2284.
        2002.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        4,500원
        2286.
        2002.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        5,400원
        2287.
        2001.12 구독 인증기관 무료, 개인회원 유료
        Two species, Marietta carnesi (Howard) and M. picta (Andre) are reported for the first time from Korea and a key is given for separating the females.
        4,000원
        2288.
        2001.12 구독 인증기관 무료, 개인회원 유료
        The genus Arrhenophagus Aurivillius comprising one species, A. chionaspidis Aurivillius is reported for the first time from Korea.
        3,000원
        2289.
        2001.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We study the properties of supernova (SN) driven interstellar turbulence with a numerical magnetohydrodynamic (MHD) model. Calculations were done using the RIEMANN framework for MHD, which is highly suited for astrophysical flows because it tracks shocks using a Riemann solver and ensures pressure positivity and a divergence-free magnetic field. We start our simulations with a uniform density threaded by a uniform magnetic field. A simplified radiative cooling curve and a constant heating rate are also included. In this radiatively-cooling magnetized medium, we explode SNe one at a time at randomly chosen positions with SN explosion rates equal to and 12 times higher than the Galactic value. The evolution of the system is basically determined by the input energy of SN explosions and the output energy of radiative cooling. We follow the simulations to the point where the total energy of the system, as well as thermal, kinetic, and magnetic energy individually, has reached a quasi-stationary value. From the numerical experiments, we find that: i) both thermal and dynamical processes are important in determining the phases of the interstellar medium, and ii) the power index n of the B-p n relation is consistent with observed values.
        3,000원
        2290.
        2001.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate the morphology of Active Galactic Nuclei(AGN) jets. AGN jets propagate over kpc ~ Mpc and their beam velocities are close to the speed of light. The reason why many jets propagate over so long a distance and sustain a very collimated structure is not well understood. It is argued that some dimensionless parameters, the density and the pressure ratio of the jet beam and the ambient gas, the Mach number of the beam, and relative speed of the beam compared to the speed of light, are very useful to understand the morphology of jets namely, bow shocks, cocoons, nodes etc. The role of each parameters has been studied by numerical simulations. But more research is necessary to understand it systematically. We have developed 2D relativistic hydrodynamic code to analyze relativistic jets. We pay attention to the propagation velocity which is derived from 1D momentum balance in the frame of the working surface. We show some of our models and discuss the dependence of the morphology of jets on the parameter.
        3,000원
        2291.
        2001.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Some authors have concluded that spiral structures and shocks do not develop if an adiabatic index ɤ > 1.16 is adopted in accretion disc modelling, whilst others have claimed that they obtained well defined spirals and shocks adopting a ɤ = 1.2 and a M2/ M1 = 1 stellar mass ratio. In our opinion, it should be possible to develop spiral structures for low compressibility gas accretion discs if the primary component is a black hole. We considered a primary black hole of 8M⊙ and a small secondary component of 0.5M⊙ to favour spiral structures formations and possible spiral shocks via gas compression due to a strong gravitational attraction. We performed two 3D SPH simulations and two 2D SPH simulations and characterized a low compressibility model and a high compressibility model for each couple of simulations. 2D models reveal spiral structures existence. Moreover, spiral shocks are also evident in high compressibility 2D model at the outer disc edge. We believe that we could develop even well defined spiral shocks considering a more massive primary component.
        3,000원
        2292.
        2001.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the whole basis of numerical method and useful formulae for general relativistic magnetohydrodynamic simulations in Kerr space-time.
        4,000원
        2295.
        2001.10 구독 인증기관·개인회원 무료