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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Astronomy and Space Sciences
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Journal DOI :
The Korean Space Science Society
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Volume & Issues
Volume 20, Issue 4 - Dec 2003
Volume 20, Issue 3 - Sep 2003
Volume 20, Issue 2 - Jun 2003
Volume 20, Issue 1 - Mar 2003
Selecting the target year
EQUIPARTITION JET MODEL FOR THE SEYFERT 1 GALAXY 3C120
Hyung, Siek ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 163~174
DOI : 10.5140/JASS.2003.20.3.163
The motion of 3C 120 Jet relative to the core is reasonably uniform and the VLBI scale jet connects outwards to a VLA ~ 100kpc scale. We measured the jet width variation from the center and found some indication of a power law which indicates the jet expands roughly with a constant opening angle and a constant flow velocity,
, from subparsec scales to ~ 100 kpc. With such a constant flow velocity and based on other physical parameters deduced from observed emission characteristics of the jet, we have established an equipartition jet model which might accommodate the basic parameters of the jet on subparsec scales, with which one can fit the radio intensities over all the scale of the jet even to ~100 kpc.
POPULATION SYNTHESIS MODELS FOR NORMAL GALAXIES WITH DUSTY DISKS
Suh, Kyung-Won ; Kim, Mi-Ryang ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 175~184
DOI : 10.5140/JASS.2003.20.3.175
To investigate the SEDs of galaxies considering the dust extinction processes in the galactic disks, we present the population synthesis models for normal galaxies with dusty disks. We use PEGASE (Fioc & Rocca-Volmerange 1997) to model them with standard input parameters for stars and new dust parameters. We find that the model results are strongly dependent on the dust parameters as well as other parameters (e.g. star formation history). We compare the model results with the observations and discuss about the possible explanations. We find that the dust opacity functions derived from studies of asymptotic giant branch stars are useful for modeling a galaxy with a dusty disk.
A DESIGN STUDY OF 100㎓ BAND LOCAL OSCILLATOR SYSTEM BY USING YIG OSCILLATOR
Lee, Chang-Hoon ; Kim, K.D. ; Kim, H.R. ; Jung, M.H. ; Han, S.T. ; Jae, D.H. ; Kim, T.S. ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 185~196
DOI : 10.5140/JASS.2003.20.3.185
In this paper, we make a design study for a local oscillator system of the 100 ㎓ band cosmic radio receiving system. We use the YIG oscillator with digital driver which is the main oscillator. This oscillator has a good frequency and phase stability at some temperature variation, and the easy computer aided control characteristics. This total system designed to two subsystem, first is the oscillator system include YIG oscillator, tripler, harmonic mixer and triplexer etc., second is the PLL system to supply the precise and stable local oscillator frequency to mixer. The proposed local oscillator system in this paper can be used in a single or multi pixel receiver because this system can be lock the local oscillator frequency automatically using PC.
DEVELOPMENT OF iRTK (iNVERTED REAL-TIME KINEMATIC) SYSTEM BASED ON THE INTERNET
Joh, Jeong-Ho ; Park, Jong-Uk ; Choi, Byung-Kyu ; Park, Pil-Ho ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 197~204
DOI : 10.5140/JASS.2003.20.3.197
We demonstrated positioning accuracy of iRTK system, which has been developed by Korea Astronomy Observatory, using a low-price GPS receiver. Each four different baseline positioning tests using the iRTK system, we certified 1-3 meters level positioning accuracy of the iRTK system. While the iRTK is similar to conventional RTK at coverage and accuracy, the iRTK positioning carried out from data processing center. And also, the iRTK system has no limit of data communication coverage because of using wire/wireless Internet. But the iRTK system has a weakness of short available coverage within 5km. Therefore we discussed a plan to adopt VRS (Virtual Reference System) as completion of the iRTK system preparing nation-wide iRTK service in near future.
ATTITUDE STABILITY OF A SPACECRAFT WITH SLOSH MASS SUBJECT TO PARAMETRIC EXCITATION
Kang, Ja-Young ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 205~216
DOI : 10.5140/JASS.2003.20.3.205
The attitude motion of a spin-stabilized, upper-stage spacecraft is investigated based on a two-body model, consisting of a symmetric body, representing the spacecraft, and a spherical pendulum, representing the liquid slag pool entrapped in the aft section of the rocket motor. Exact time-varying nonlinear equations are derived and used to eliminate the drawbacks of conventional linear models. To study the stability of the spacecraft's attitude motion, both the spacecraft and pendulum are assumed to be in states of steady spin about the symmetry axis of the spacecraft and the coupled time-varying nonlinear equation of the pendulum is simplified. A quasi-stationary solution to that equation and approximate resonance conditions are determined in terms of the system parameters. The analysis shows that the pendulum is subject to a combination of parametric and external-type excitation by the main body and that energy from the excited pendulum is fed into the main body to develop the coning instability. In this paper, numerical examples are presented to explain the mechanism of the coning angle growth and how angular momenta and disturbance moments are generated.
RELIABILITY ANALYSIS OF THE MSC SYSTEM
Kim, Young-Soo ; Lee, Do-Kyoung ; Lee, Chang-Ho ; Woo, Sun-Hee ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 217~226
DOI : 10.5140/JASS.2003.20.3.217
MSC (Multi-Spectral Camera) is the payload of KOMPSAT-2, which is being developed for earth imaging in optical and near-infrared region. The design of the MSC is completed and its reliability has been assessed from part level to the MSC system level. The reliability was analyzed in worst case and the analysis results showed that the value complies the required value of 0.9. In this paper, a calculation method of reliability for the MSC system is described, and assessment result is presented and discussed.
DESIGN AND IMPLEMENTATION OF THE MISSION PLANNING FUNCTIONS FOR THE KOMPSAT-2 MISSION CONTROL ELEMENT
Lee, Byoung-Sun ; Kim, Jae-Hoon ;
Journal of Astronomy and Space Sciences, volume 20, issue 3, 2003, Pages 227~238
DOI : 10.5140/JASS.2003.20.3.227
Spacecraft mission planning functions including event prediction, mission scheduling, command planning, and ground track display have been developed for the KOMPSAT-2 mission operations. Integrated event prediction functions including satellite orbital events, user requested imaging events, and satellite operational events have been implemented. Mission scheduling functions have been realized to detect the mission conflicts considering the user specified constraints and resources, A conflict free mission scheduling result is mapped into the spacecraft command sequences in the command planning functions. The command sequences are directly linked to the spacecraft operations using eXtensible Markup Language(XML) for command transmission. Ground track display shows the satellite ground trace and mission activities on a digitized world map with zoom capability.