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TRAO Multi-beam Legacy Survey of Nearby Filamentary Molecular Clouds : Progress Report
ShinYoung Kim,Eun Jung Chung,Chang Won Lee,Philip C. Myers,Paola Caselli,Mario Tafalla,Gwanjeong Kim,Miryang Kim,Archana Soam,Maheswar Gophinathan,Tie Liu,Kyounghee Kim,Woojin Kwon,Jongsoo Kim 한국천문학회 2017 天文學會報 Vol.42 No.1
THE VELOCITY FIELD OF SUPERNOVA-DRIVEN TURBULENCE IN THE INTERSTELLAR MEDIUM
JONGSOO KIM 한국천문학회 2004 Journal of The Korean Astronomical Society Vol.37 No.5
We perform numerical experiments on supernova-driven turbulent ows in order to see whetheror not supernovae play a major role in driving turbulence in the interstellar medium. In a (200pc)3computational box, we set up, as initial conditions, uniformly magnetized gas distributions with dierentpairs of hydrogen number densities and magnetic eld strengths, which cover the observed values in theGalactic midplane. We then explode supernovae at randomly chosen positions at a Galactic explosionrate and follow up the evolution of the supernova-driven turbulent ows by integrating numericallythe ideal MHD equations with cooling and heating terms. From the numerical experiments we ndthat the density-weighted velocity dispersions of the ows are in the range of 5-10 km s1, which areconsistent with the observed velocity dispersions of cold and warm neutral media. Additionally, we ndthat strong compressible ows driven by supernova explosions quickly change into solenoidal flows.
Prenatal Stress Induces Skeletal Malformations in Mouse Embryos
Jongsoo Kim,Hyo Jung Yun,Ji-Yeon Lee,Myoung Hee Kim 대한의생명과학회 2015 Biomedical Science Letters Vol.21 No.1
Dexamethasone, a synthetic glucocorticoid (GC), is clinically administered to woman at risk for premature labor to induce fetal lung maturation. However, exposure to repeated or excess GCs leads to intrauterine growth restriction (IUGR) and subsequently increases risk of psychiatric and cardio-metabolic diseases in later life through fetal programming mechanisms. GCs are key mediators of stress responses, therefore, maternal nutrient restriction or psychological stress during pregnancy also causes negative impacts on birth and neurodevelopment outcome of fetuses, and other congenital defects, such as craniofacial and skeletal abnormalities. In this study, to examine the effect of prenatal stress on fetal skeletal development, dexamethasone (1 mg/kg [DEX1] or 10 mg/kg [DEX10] maternal body weight per day) was administered intraperitoneally at gestational day 7.5~9.5 and the skeletons were prepared from embryos at day 18.5. Seven out of eighteen (39%) embryos treated with DEX10 showed axial skeletal abnormalities in either the T13 or L1 vertebrae. In addition, examination of the sternum revealed that xiphoid process, the protrusive triangular part of the lower end of the sternum, was bent more outward or inward in DEX group embryos. In conclusion, our findings suggest a possible link to the understanding of the effect of uterine environment to the fetal skeletal features.
Kim, Hyosun,Liu, Sheng-Yuan,Hirano, Naomi,Zhao-Geisler, Ronny,Trejo, Alfonso,Yen, Hsi-Wei,Taam, Ronald E.,Kemper, Francisca,Kim, Jongsoo,Byun, Do-Young,Liu, Tie IOP Publishing 2015 The Astrophysical journal Vol.814 No.1
<P>CIT 6 is a carbon star in the transitional phase from the asymptotic giant branch (AGB) to the protoplanetary nebulae (pPNs). Observational evidences of two point sources in the optical, circumstellar arc segments in an HC3N line emission, and a bipolar nebula in near-infrared provide strong support for the presence of a binary companion. Hence, CIT 6 is very attractive for studying the role of companions in the AGB-pPN transition. We have carried out high-resolution (CO)-C-12 J = 2-1 and (CO)-C-13 J = 2-1 observations of CIT 6 with the Submillimeter Array combined with the Submillimeter Telescope (single-dish) data. The (CO)-C-12 channel maps reveal a spiral-shell pattern connecting the HC3N segments in a continuous form. and an asymmetric outflow corresponding to the near-infrared bipolar nebula. Rotation of the (CO)-C-12 channel peak position may be related to the inner spiral winding and/or the bipolar outflow. An eccentric orbit binary is suggested for the presence. of an anisotropic mass loss to the west and a double spiral pattern. The lack of interarm emission to the west may indicate a feature corresponding to the periastron passage of a highly eccentric orbit of the binary. Spatially averaged radial and spectral profiles of (CO)-C-12 J = 2-1 and (CO)-C-13 J = 2-1 are compared with simple spherical radiative transfer models, suggesting a change of (CO)-C-12/(CO)-C-13 abundance ratio from similar to 30 to similar to 50 inward in the CSE of CIT 6. The millimeter continuum emission is decomposed into extended dust thermal emission (spectral index similar to -2.4) and compact emission from radio photosphere (spectral index similar to -2.0).</P>
A 8-GHz SiGe HBT VCO Design on a Low Resistive Silicon Substrate Using GSML
Jongsoo Lee,Young-Gi Kim,Eun-Jin Lee,Chang-Woo Kim,Roblin, P. IEEE 2007 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 1 R Vol.54 No.10
<P>A practical layout method called ground shield microstrip lines (GSML) is investigated for the reliable design of high frequency interconnection lines on a low resistive silicon substrate. GSML facilitates the prediction of parasitic networks at the expense of introducing negligible loss. The microwave performance of a GSML line structure is compared to that of a conventional metal line on the same standard silicon substrate (20 Omegamiddotcm). Then, the GSML structure is applied to an 8-GHz SiGe heterojunction bipolar transistor (HBT) voltage-controlled oscillator (VCO) circuit. The GSML method replaces the post layout simulation and reduces iteration time, increasing design efficiency. A fully integrated differential tuning SiGe HBT 8-GHz VCO is designed and tested. The measured phase noise for the VCO is dBc/Hz at 1-MHz offset with an output power of dBm.</P>
An Isothermal Mganetohydrodynamic Code and Its Application to the Parker Instability
KIM JONGSOO,RYU DONGSU,JONES T. W.,HONG S. S. The Korean Astronomical Society 2001 Journal of The Korean Astronomical Society Vol.34 No.4
As a companion to an adiabatic version developed by Ryu and his coworkers, we have built an isothermal magnetohydrodynamic code for astrophysical flows. It is suited for the dynamical simulations of flows where cooling timescale is much shorter than dynamical timescale, as well as for turbulence and dynamo simulations in which detailed energetics are unimportant. Since a simple isothermal equation of state substitutes the energy conservation equation, the numerical schemes for isothermal flows are simpler (no contact discontinuity) than those for adiabatic flows and the resulting code is faster. Tests for shock tubes and Alfven wave decay have shown that our isothermal code has not only a good shock capturing ability, but also numerical dissipation smaller than its adiabatic analogue. As a real astrophysical application of the code, we have simulated the nonlinear three-dimensional evolution of the Parker instability. A factor of two enhancement in vertical column density has been achieved at most, and the main structures formed are sheet-like and aligned with the mean field direction. We conclude that the Parker instability alone is not a viable formation mechanism of the giant molecular clouds.