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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 24, Issue 4 - Dec 2007
Volume 24, Issue 3 - Sep 2007
Volume 24, Issue 2 - Jun 2007
Volume 24, Issue 1 - Mar 2007
Selecting the target year
VARIATION IN NORTH-SOUTH ASYMMETRY OF SUN SPOT AREA
Chang, Heon-Young ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 91~98
DOI : 10.5140/JASS.2007.24.2.091
The existence of the North-South asymmetry of the solar activity is widely accepted even though the phenomenon is not yet satisfactorily understood. We have studied the temporal variations in the North-South asymmetry of the sunspot area during the period from May in 1874 to April in 2007. The combined data have been examined for periodicity in the solar activity North-South asymmetry. We have found that (i) solar northern and southern hemispheres show an asymmetric behavior, in terms of a sunspot area, (ii) sunspot areas in northern and southern hemispheres show clearly the 11 year periodicity when they were analyzed separately, as they do when analyzed together, (iii) in addition to the general 11 year periodicity in both northern and southern hemisphere solar activities, there are also noticeable shorter periodicities other than the 11 year periodicity in the asymmetry in North-South activity. Finally, we conclude by pointing out the importance of studying the North-South asymmetry of the solar activity.
PHOTOMETRIC OBSERVATIONS OF THE CONTACT BINARY SYSTEM CC COM
Jeong, Jang-Hae ; Kim, Chun-Hwey ; Kim, Yong-Gi ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 99~110
DOI : 10.5140/JASS.2007.24.2.099
A total of 824 observations (206 in
, 206 in
, 206 in
, 206 in
for CC Com were made on 3 nights from March 3 to April 3 in 2002 using the 61cm telescope with 2K CCD camera of the Sobaeksan Optical Astronomy Observatory of KASI. From our observations 9 times of minimum light were newly determined. Combined analysis of our new BVRI light curves with the double-lined radial velocity curves of Pribulla et al. (2007) were made with the 2004 Wilson-Devinney(WD) binary model code to yield new physical parameters of the CC Com system. Small asymmetries in light curves were explained with the adoption of two hot spots on the cool secondary.
SOME CHARACTERISTICS OF ENERGETIC NEUTRAL ATOM STORM ON OCTOBER 3, 2001
Lee, D.Y. ; Choi, C.R. ; Kim, Hee-Jeong ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 111~118
DOI : 10.5140/JASS.2007.24.2.111
We have studied energetic neutral atom (ENA) disturbances during the magnetic storm main phase that occurred on October 3,2001, using the ENA data from the HENA instrument onboard the IMAGE spacecraft. We find that the main phase is characterized by five ENA enhancement events that occurred quasi-periodically. The repetitive ENA enhancements are most significant in the highest energy (138-222 keV) oxygen channel and become less significant for hydrogen and in lower energies. Also they are separated by
hrs, which is well below an average period usually seen for other repetitive injection events.
STUDY ON THE PARTICLE INJECTIONS DURING HILDCAA INTERVALS
Kim, Hee-Jeong ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 119~124
DOI : 10.5140/JASS.2007.24.2.119
The relation between substorm occurrences and HILDCAA events has been an issue. We have studied the association of particle injections with substorm onsets during HILDCAA intervals for the first half of year 2003. The examination of aurora images observed by IMAGE spacecraft and electron flux data measured by LANL satellites exhibits a close association of repetitive particle injections with substorm activity. We also find that HILDCAA events can occur equally frequently during slow speed solar wind streams as long as the interplanetary magnetic field exhibits Alfvenic wave feature.
DRAG EFFECT OF KOMPSAT-1 DURING STRONG SOLAR AND GEOMAGNETIC ACTIVITY
Park, J. ; Moon, Y.J. ; Kim, K.H. ; Cho, K.S. ; Kim, H.D. ; Kim, Y.H. ; Park, Y.D. ; Yi, Y. ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 125~134
DOI : 10.5140/JASS.2007.24.2.125
In this paper, we analyze the orbital variation of the Korea Multi-Purpose SATellite-1(KOMPSAT-1) in a strong space environment due to satellite drag by solar and geomagnetic activities. The satellite drag usually occurs slowly, but becomes serious satellite drag when the space environment suddenly changes via strong solar activity like a big flare eruption or coronal mass ejections(CMEs). Especially, KOMPSAT-1 as a low earth orbit satellite has a distinct increase of the drag acceleration by the variations of atmospheric friction. We consider factors of solar activity to have serious effects on the satellite drag from two points of view. One is an effect of high energy radiation when the flare occurs in the Sun. This radiation heats and expands the upper atmosphere of the Earth as the number of neutral particles is suddenly increased. The other is an effect of Joule and precipitating particle heating caused by current of plasma and precipitation of particles during geomagnetic storms by CMEs. It also affects the density of neutral particles by heating the upper atmo-sphere. We investigate the satellite drag acceleration associated with the two factors for five events selected based on solar and geomagnetic data from 2001 to 2002. The major results can be summarized as follows. First, the drag acceleration started to increase with solar EUV radiation with the best cross-correlation (r = 0.92) for 1 day delayed F10.7. Second, the drag acceleration and Dst index have similar patterns when the geomagnetic storm is dominant and the drag acceleration abruptly increases during the strong geomagnetic storm. Third, the background variation of the drag accelerations is governed by the solar radiation, while their short term (less than a day) variations is governed by geomagnetic storms.
ANALYSTS OF DAMAGE PROBABILITY FOR COLLISION BETWEEN SPACE DEBRIS AND A SATELLITE IN LOW-EARTH ORBIT
Lee, Jae-Eun ; Park, Sang-Young ; Kim, Young-Rok ; Choi, Kyu-Hong ; Kim, Eung-Hyun ; Kim, Gyu-Sun ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 135~144
DOI : 10.5140/JASS.2007.24.2.135
Space environment becomes more hazardous for satellite because of increasing number of space debris. This research is to analyze collision hazards between KOMPSAT 3 in low-earth orbit and space debris generated by the explosion of FengYun satellite on the January 11, 2007. Based on the observed data of the space debris from FengYun satellite, the mass and number distribution of the debris are estimated including undetectable debris from the explosion of FengYun satellite. The spatial density and flux for the space debris can be calculated according to size. This study also brings out the analysis for the assessment of collision probability and damage probability. The algorithm developed in the current paper can be used to estimate the level of risk due to space debris for the satellites that will be launched in the future.
ANTENNA POINTING TO THE GEO SATELLITE USING CONVERTED NORAD TLE FROM OSCULATING ORBITAL ELEMENTS
Lee, Byoung-Sun ; Kim, Hae-Yeon ; Hwang, Yoo-La ; Kim, Jae-Hoon ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 145~154
DOI : 10.5140/JASS.2007.24.2.145
Antenna pointing analysis for a geostationary satellite has been performed for using the NORAD Two-Line-Elements (TLE) converted from osculating Keplerian orbital elements. In order to check the possibility of the reception of the satellite signal, the antenna offset angles have been derived for the Communications, Ocean, and Meteorological Satellite (COMS) which carries out weekly East-West and North-South station-keeping maneuvers and twice a day thruster assisted momentum dumping. Throughout the analysis, it is shown that the use of converted NORAD TLE simplifies the antenna pointing related interfaces in satellite mission control system. For a highly eccentric transfer orbit cases, further analysis presents that the converted NORAD TLE from near apogee gives more favorable results.
DESIGN OF COMPACT PARTICLE DETECTOR SYSTEM USING FPGA FOR SPACE PARTICLE ENVIRONMENT MEASUREMENT
Ryu, K. ; Oh, D.S. ; Kim, S.J. ; Kim, H.J. ; Lee, J.J. ; Shin, G.H. ; Ko, D.H. ; Min, K.W. ; Hwang, J.A. ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 155~166
DOI : 10.5140/JASS.2007.24.2.155
We have designed a high resolution proton and electron telescope for the detection of high energy particles, which constitute a major part of the space environment. The flux of the particles, in the satellite orbits, can vary abruptly according to the position and solar activities. In this study, a conceptual design of the detector, for adapting these variations with a high energy resolution, was made and the performance was estimated. In addition, a parallel processing algorithm was devised and embodied using FPGA for the high speed data processing, capable of detecting high flux without losing energy resolution, on board a satellite.
STUDY ON THE STRUCTURE AND WORKING PRINCIPLE OF SONG I-YŎNG'S ARMILLARY CLOCK
Lee, Yong-Sam ; Kim, Sang-Hyuk ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 167~178
DOI : 10.5140/JASS.2007.24.2.167
We analysis the structure of Song
Armillary Clock, a Korean National Treasure (No. 230) that is displayed at Korea University Museum. This Armillary Clock is only one remained in east Asia, but does not working because some parts had been broken away. We measured this remains and reconstructed a working model of the astronomical armillary sphere system of the his armillary clock, which system is consisted of Solar and lunar moving devices.
THE DESIGN AND ANALYSIS PROGRAM FOR THE DEVELOPMENT OF LEO SATELLITE ELECTRICAL POWER SUBSYSTEM
Lee, Sang-Kon ; Ra, Sung-Woong ;
Journal of Astronomy and Space Sciences, volume 24, issue 2, 2007, Pages 179~194
DOI : 10.5140/JASS.2007.24.2.179
The design and analysis of satellite power subsystem is an important driver for the mass, size, and capability of the satellite. Every other satellite subsystem is affected by the power subsystem, and in particular, important issues such as launch vehicle selection, thermal design, and structural design are largely influenced by the capabilities and limitations of the power system. This paper introduces a new electrical power subsystem design program for the rapid development of LEO satellite and shows an example of design results using other LEO satellite design data. The results shows that the proposed design program can be used the optimum sizing and the analytical prediction of the on-orbit performance of satellite electrical power subsystem.