Estimation of Magnetic Field Strength in the Turbulent Warm Ionized Medium (2009)
Wu, Qingwen, Kim, Jongsoo, Ryu, Dongsu, Cho, Jungyeon, Alexander, Paul
We studied Faraday rotation measure (RM) in turbulent media with the rms Mach number of unity, using isothermal, magnetohydrodynamic turbulence simulations. Four cases with different values of...
Molecular Line Profiles from a Core Forming in a Turbulent Cloud (2009)
We calculate the evolution of molecular line profiles of HCO$^+$ and C$^{18}$O toward a dense core thatis forming inside a magnetized turbulent molecular cloud. Features of the profiles can be...
An Explicit Scheme for Incorporating Ambipolar Diffusion in a Magnetohydrodynamics Code (2008)
Choi, Eunwoo, Kim, Jongsoo, Wiita, Paul J.
We describe a method for incorporating ambipolar diffusion in the strong coupling approximation into a multidimensional magnetohydrodynamics code based on the total variation diminishing scheme....
Formation and Properties of Molecular Cloud Cores (2008)
Dib, Sami, Galvan-Madrid, Roberto, Kim, Jongsoo, Vazquez-Semadeni, Enrique
In this paper, we review some of the properties of dense molecular cloud cores. The results presented here rely on three-dimensional numerical simulations of isothermal, magnetized, turbulent, and...
Numerical Simulations of a Protostellar Outflow Colliding with a Dense Molecular Cloud (2008)
Baek, Chang Hyun, Kim, Jongsoo, Choi, Minho
High-resolution SiO observations of the NGC 1333 IRAS 4A star-forming region showed a highly collimated outflow with a substantial deflection. The deflection was suggested to be caused by the...
The Nature of the Velocity Field in Molecular Clouds. I. The Non-Magnetic Case (2008)
Vazquez-Semadeni, Enrique, Gonzalez, Ricardo F., Ballesteros-Paredes, Javier, Gazol, Adriana, Kim, Jongsoo
We present three numerical simulations of randomly driven, isothermal, non-magnetic, self-gravitating turbulence with different rms Mach numbers Ms and physical sizes L, but approximately the same...
Physical Properties of Tidal Features in Interacting Disk Galaxies (2008)
Oh, Sang Hoon, Kim, Woong-Tae, Lee, Hyung Mok, Kim, Jongsoo
We explore tidal interactions of a galactic disk with Toomre parameter Q ~ 2 embedded in rigid halo/bulge with a point mass companion moving in a prescribed parabolic orbit. Tidal interactions...
Core Mass Function: The Role of Gravity (2008)
Dib, Sami, Brandenburg, Axel, Kim, Jongsoo, Gopinathan, Maheswar, Andre, Philippe
We analyze the mass distribution of cores formed in an isothermal, magnetized, turbulent, and self-gravitating nearly critical molecular cloud model. Cores are identified at two density threshold...
Highly Efficient Comparator Design Automation for TIQ Flash A/D Converter (2008)
KIM, Insoo, YOO, Jincheol, KIM, JongSoo, CHOI, Kyusun
Threshold Inverter Quantization (TIQ) technique has been gaining its importance in high speed flash A/D converters due to its fast data conversion speed. It eliminates the need of resistor ladders...
The Parker Instability under a Linear Gravity (2007)
Jongsoo Kim, Seung Soo Hong, Dongsu Ryu
A linear stability analysis has been done to a magnetized disk under a linear gravity. We have reduced the linearized perturbation equations to a second-order differential equation which resembles...
Primordial Mass Segregation in Starburst Stellar Clusters (2007)
Dib, Sami, Shadmehri, Mohsen, Gopinathan, Maheswar, Kim, Jongsoo, Henning, Thomas
We present a model to explain the mass segregation and shallow mass functions observed in the central parts of dense and young starburst stellar clusters. The model assumes that the initial...
The Origin of the Arches Stellar Cluster Mass Function (2007)
Dib, Sami, Kim, Jongsoo, Shadmehri, Mohsen
We investigate the time evolution of the mass distribution of pre-stellar cores (PSCs) and their transition to the initial stellar mass function (IMF) in the central parts of a molecular cloud (MC)...
Galván-Madrid, Roberto, Vázquez-Semadeni, Enrique, Kim, Jongsoo, Ballesteros-Paredes, Javier
We present measurements of the mean dense core lifetimes in numerical simulations of magnetically supercritical, turbulent, isothermal molecular clouds, in order to compare with observational...
On the Gravitational Boundedness of Small Scale Structures in Molecular Clouds (2006)
We investigate, in a set of 3D numerical simulations of driven, magnetized, isothermal, and self-gravitating molecular clouds (MCs), the statistical correlations between the energy ratios...
The Virial Balance of Clumps and Cores in Molecular Clouds (2006)
Dib, Sami, Kim, Jongsoo, Vazquez-Semadeni, Enrique, Burkert, Andreas, Shadmehri, Mohsen
We study the instantaneous virial balance of clumps and cores (CCs) in 3D simulations of driven, MHD, isothermal molecular clouds (MCs). The models represent a range of magnetic field strengths in...
Three-dimensional simulations of the parker instability in a uniformly-rotating disk (2006)
Dongsu Ryu, T. W. Jones, Jongsoo Kim
Three-dimensional simulations of the parker instability in a uniformly-rotating disk
The Thermal Pressure Distribution in the Atomic ISM (2006)
Adriana Gazol, Enrique Vázquez Semadeni, Jongsoo Kim
The Thermal Pressure Distribution in the Atomic ISM
Baek, Chang Hyun, Ryu, Dongsu, Kang, Hyesung, Kim, Jongsoo
Thermal-gravitational instability (TGI) is studied in the protogalactic environment. We extend our previous work, where we found that dense clumps first form out of hot background gas by thermal...
Ballesteros-Paredes, Javier, Gazol, Adriana, Kim, Jongsoo, Klessen, Ralf S., Jappsen, Anne-Katharina, Tejero, Epimenio, ...
We investigate the core mass distribution (CMD) resulting from numerical models of turbulent fragmentation of molecular clouds. In particular we study its dependence on the sonic root-mean-square...
Star Formation Efficiency in Driven, Supercritical, Turbulent Clouds (2005)
Vazquez-Semadeni, Enrique, Kim, Jongsoo, Ballesteros-Paredes, Javier
We present measurements of the star formation efficiency (SFE) in 3D numerical simulations of driven turbulence in supercritical, ideal-MHD, and non-magnetic regimes, characterized by their mean...
Density Power Spectrum of Compressible Hydrodynamic Turbulent Flows (2005)
Turbulent flows are ubiquitous in astrophysical environments, and understanding density structures and their statistics in turbulent media is of great importance in astrophysics. In this paper, we...
Baek, Chang Hyun, Kang, Hyesung, Kim, Jongsoo, Ryu, Dongsu
We study thermal-gravitational instability in simplified models for protogalactic halos using three-dimensional hydrodynamic simulations. The simulations followed the evolution of gas with radiative...
The pressure distribution in thermally bistable turbulent flows (2005)
Gazol, Adriana, Vazquez-Semadeni, Enrique, Kim, Jongsoo
We present a systematic numerical study of the effect of turbulent velocity fluctuations on the thermal pressure distribution in thermally bistable flows. The simulations employ a random turbulent...
The Distribution of Pressures in a Supernova-Driven Interstellar Medium. I. Magnetized Medium (2004)
Mac Low, Mordecai-Mark, Balsara, Dinshaw S., Kim, Jongsoo, Avillez, Miguel A.
Observations have suggested substantial departures from pressure equilibrium in the interstellar medium (ISM) in the plane of the Galaxy, even on scales under 50 pc. Nevertheless, multi-phase models...
The Lifetimes and Evolution of Molecular Cloud Cores (2004)
Vazquez-Semadeni, Enrique, Kim, Jongsoo, Shadmehri, Mohsen, Ballesteros-Paredes, Javier
We discuss the lifetimes and evolution of clumps and cores formed as turbulent density fluctuations in nearly isothermal molecular clouds. In the non-magnetic case, clumps are unlikely to reach a...
Balsara, Dinshaw, Kim, Jongsoo
In recent years, several different strategies have emerged for evolving the magnetic field in numerical MHD. Some of these methods can be classified as divergence-cleaning schemes, where one evolves...
Numerical Study of Compressible Magnetohydrodynamic Turbulence in Two Dimensions (2003)
Lee, Hyesook, Ryu, Dongsu, Kim, Jongsoo, Jones, T. W., Balsara, Dinshaw
We have studied forced turbulence of compressible magnetohydrodynamic (MHD) flows through two-dimensional simulations with different numerical resolutions. First, hydrodynamic turbulence with Mach...
The Effect of Cosmic Ray Diffusion on the Parker Instability (2003)
Ryu, Dongsu, Kim, Jongsoo, Hong, Seung Soo, Jones, T. W.
The Parker instability, which has been considered as a process governing the structure of the interstellar medium, is induced by the buoyancy of magnetic field and cosmic rays. In previous studies,...
A Power and Resolution Adaptive Flash Analogto-Digital (2002)
Jincheol Yoo, Daegyu Lee, Kyusun Choi, Jongsoo Kim
A new power and resolution adaptive flash ADC, named PRA-ADC, is proposed. The PRA-ADC enables exponential power reduction with linear resolution reduction. Unused parallel voltage comparators are...
The Parker Instability in 3-D: Corrugations and Superclouds Along the Carina-Sagittarius Arm (2001)
Franco, Jose, Kim, Jongsoo, Alfaro, Emilio J., Hong, Seung Soo
Here we present three-dimensional MHD models for the Parker instability in a thick magnetized disk, including the presence of a spiral arm. The $B$-field is assumed parallel to the arm, and the model...
The Effect of the Random Magnetic Field Component on the Parker Instability (2001)
The Parker instability is considered to play important roles in the evolution of the interstellar medium. Most studies on the development of the instability so far have been based on an initial...
The Distribution of Pressures in a Supernova-Driven Interstellar Medium (2001)
Mac Low, Mordecai-Mark, Balsara, Dinshaw, Avillez, Miguel A., Kim, Jongsoo
Observations have suggested substantial departures from pressure equilibrium in the interstellar medium (ISM) in the plane of the Galaxy, even on scales under 50 pc. Nevertheless, multi-phase models...
Three-dimensional Simulations of the Parker Instability in a Uniformly-rotating Disk (2001)
Kim, Jongsoo, Ryu, Dongsu, Jones, T. W.
We investigate the effects of rotation on the evolution of the Parker instability in an exponentially-stratified and uniformly-rotating magnetized gas disk by carrying out three-dimensional numerical...
The Collisions of HVCs with a Magnetized Gaseous Galactic Disk (2001)
Franco , José, Kim , Jongsoo, Martos , Marco, Santillán , Alfredo
We discuss 2-D MHD numerical simulations for the interaction of high-velocit y clouds with a magnetized Galactic disk. The initial magnetic field is oriented parallel to the disk, and we consider two...
The Parker Instability in a Thick Gaseous Disk II: Numerical Simulations in 2D (2000)
Santillan, Alfredo, Kim, Jongsoo, Franco, Jose, Martos, Marco, Hong, S. S., Ryu, Dongsu
We present 2D, ideal-MHD numerical simulations of the Parker instability in a multi-component warm disk model. The calculations were done using two numerical codes with different algorithms, TVD and...
Three-Dimensional Simulations Of The Parker Instability In A Uniformly-Rotating Disk (2000)
Jongsoo Kim, Dongsu Ryu, T. W. Jones
We investigate the nonlinear eects of uniform rotation on the Parker instability in an exponentially-strati ed disk through high-resolution simulations. During the linear stage, the speed of gas...
Three-Dimensional Simulations Of The Parker Instability In A Uniformly-Rotating Disk (2000)
Jongsoo Kim, Dongsu Ryu, T. W. Jones
We investigate the nonlinear e#ects of uniform rotation on the Parker instability in an exponentially-stratified disk through high-resolution simulations. During the linear stage, the speed of gas...
Three-Dimensional Simulations of the Parker Instability in a Uniformly-rotating Disk (1999)
Kim, Jongsoo, Ryu, Dongsu, Jones, T. W.
We investigate the nonlinear effects of uniform rotation on the Parker instability in an exponentially-stratified disk through high-resolution simulations. During the linear stage, the speed of gas...
Kim, Jongsoo, Franco, Jose, Hong, S. S., Santillan, Alfredo, Martos, Marco A.
A linear stability analysis of a multi-component and magnetized Galactic disk model is presented. The disk model uses the observed stratifications for the gas density and gravitational acceleration...
The Collisions of HVCs with a Magnetized Gaseous Galactic Disk (1998)
Santillan, Alfredo, Franco, Jose, Martos, Marco, Kim, Jongsoo
We present two-dimensional MHD numerical simulations for the interaction of high-velocity clouds with both magnetic and non-magnetic Galactic thick gaseous disks. For the magnetic models, the initial...
A Multi-dimensional Code for Isothermal Magnetohydrodynamic Flows in Astrophysics (1998)
Kim, Jongsoo, Ryu, Dongsu, Jones, T. W., Hong, S. S.
We present a multi-dimensional numerical code to solve isothermal magnetohydrodynamic (IMHD) equations for use in modeling astrophysical flows. First, we have built a one-dimensional code which is...
Three-Dimensional Evolution of the Parker Instability under a Uniform Gravity (1998)
Kim, Jongsoo, Hong, S. S., Ryu, Dongsu, Jones, T. W.
Using an isothermal MHD code, we have performed three-dimensional, high-resolution simulations of the Parker instability. The initial equilibrium system is composed of exponentially-decreasing...
A Comparative Study of the Parker Instability under Three Models of the Galactic Gravity (1998)
To examine how non-uniform nature of the Galactic gravity might affect length and time scales of the Parker instability, we took three models of gravity, uniform, linear and realistic ones. To make...
The Parker Instability under a Linear Gravity (1997)
Kim, Jongsoo, Hong, Seung Soo, Ryu, Dongsu
A linear stability analysis has been done to a magnetized disk under a linear gravity. We have reduced the linearized perturbation equations to a second-order differential equation which resembles...
Parker Instability: Continuum vs. Discrete Solutions (1996)
Jongsoo Kim, S. S. Hong, Dongsu Ryu
Since the pioneering work of Parker (1966), there have been many studies on the stability of a magnetized disk under externally given gravitational fields (Shu 1974; Zweibel & Kulsrud 1975;...
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