Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Astronomy and Space Sciences
Journal Basic Information
Journal DOI :
The Korean Space Science Society
Editor in Chief :
Volume & Issues
Volume 18, Issue 3 - Dec 2001
Volume 18, Issue 2 - Nov 2001
Volume 18, Issue 1 - Jun 2001
Selecting the target year
POSSIBLE DERIVATIONS OF ORTHO- AND PARA-
RATIOS IN THE ATMOSPHERES OF THE GIANT PLANETS USING THE
SPECTRAL STRUCTURES OF
Kim, Sang-Joon ; Lee, Yong-Sik ;
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 95~100
We have presented an ab initio model of the
spectral features of
based on the far-infrared models of McKellar & Schaefer (1991). We have shown that the intensity variations of the
features depend on the ortho/para ratios of
We have discussed the applicability of the variations to the atmospheres of the giant planets for the derivations of the ortho/para ratios. The signal to noise ratios of currently available spectra of the giant planets are not sufficient enough to derive accurate ortho/para ratios of these planets. Observations with longer exposure times and larger telescope apertures are required to obtain better spectra for the derivations of the ortho/para ratios of
in the atmospheres of the giant planets.
SPECTROSCOPIC OBSERVATIONS OF GEO-STAT10NARY SATELLITES OVER THE KOREAN PENINSULA
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 101~108
Low resolution spectroscopic observations of leo-stationary satellites over the Korean peninsula have been carried out at the KyungHee Optical Satellite Observing Facility (KOSOF) with a 40cm telescope. We have observed 9 telecommunication satellites and 1 weather satellite of 6 countries. The obtained spectral data showed that satellites could be classified and grouped with similar basic spectral feature. We divided the 10 satellites into 4 groups based on spectral slop and reflectance. It is suggested that the material types of the satellites can be determined through spectral comparisons with the ground laboratory data. We will continuously observe additional geo-stationary satellites for the accurate classification of spectral features.
ESTIMATION OF SEU THRESHOLD ENERGY FROM KITSAT-1 DATA USING AP-8 MODEL
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 109~118
KITSAT-1, launched in 1992, passes through Inner Van Allen Radiation Belt in which high energy Protons cause single event upsets(SBUs) in the main memory of KITSAT-1 OBC(On-Board Computer) 186. The present paper compares SEU data from the OBC186 with the AP-8 model of NASA/NSSDC using the Chi-Square method to estimate the SEU threshold energy. Shielding effect by the satellite body has been taken into account to model the proton fluxes at the position of OBC186, and SEUs recorded during the high solar activities have been removed to avoid the spurious result. The result shows that the SEU threshold energy of the main memory of KITSAT-1 OBC186 is estimated to be about
AN ANALYSIS OF EMBEDDING IMPEDANCE FOR Q-BAND WAVEGUIDE GUNN OSCILLATOR WITH RESONANCE POST
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 119~128
The oscillation frequency tuning range of waveguide Gunn oscillator and its stability depend sensitively on the dimensions of the resonator. Therefore the embedding impedances with the various dimensions of the resonator for Q-band (33 ∼ 50 GHz) Gunn oscillator are calculated by using HFSS (High Frequency Structure Simulator). In this paper the comparisons between theoretical results of embedding impedances as a function of frequency and that of experimental results are described. And the oscillation frequency range could be predicted by using the theoretical evaluation methods which were proposed in this paper It shows that post size has an effect on the frequency tuning characteristics of Gunn oscillator.
PRECISE ORBIT DETERMINATION OF GPS SATELLITES FOR REAL TIME APPLICATIONS
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 129~136
The accuracy of GPS applications is heavily dependent on the satellite ephemeris and earth orientation parameter. Specially applications like as the real time monitoring of troposphere and ionosphere require real time or predicted ephemeris arid earth orientation parameter with very high quality. IGS is producing IGS ultra rapid product called IGU for real time applications which includes the information of ephemeris and earth orientation. IGU is being made available twice everyday at 3:00 and 15:00 UTC arid covers 48 hours. The first 24 hours of it are based on actual GPS observations and the second 24 hours extrapolated. We will construct the processing strategy for yielding ultra rapid product and demonstrate the propriety through producing it using 48 hours data of 32 stations.
THRUSTER PERFORMANCE ESTIMATI0N OF KOREASAT F1 & F2
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 137~144
This paper presents the REA thrusters performance estimation results for the KOREASAT F1&F2 launched in 1995 The satellite tracking data obtained from the ground system from end of 1999 to beginning of the 2000 are used to estimate the thruster performance. The estimation algorithm is derived from the least square estimation theory and designed to estimate the velocity change induced by the on-boarded thruster firing as well as the orbit parameter. The estimation results show that the Koreasat F1 thruster are in bad thruster condition of 64% performance for REA when it fires in on-pulse mode. Here, the performance is defined by the ratio of the resulted velocity change to that of planned. But, in the case o( the Koreasat F2, it is found that the performance approximately reaches up to 100%, even after the 5 years of the mission.
DESIGNING A SMALL-SIZED ENGINEERING MODEL OF SOLAR EUV TELESCOPE FOR A KOREAN SATELLITE
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 145~152
For the research of solar EUV (extreme ultraviolet) radiation, we have designed a small-sifted engineering model of solar EUV telescope, which is suitable for a Korean satellite. The EUV sole. telescope was designed to observe the sun at
(He I) and
(OV) The optical system is an f/8 Ritchey-Chr rien, and the effective diameter and focal length are 80mm and 640mm, respectively. The He I and 0V filters are loaded in a filter wheel. In the detection part, the MCP (Microchannel Plate) type is Z-stack, and the channel-to-diameter radio is 40:1. MCP and CCD are connected by fiber optic taper. A commercial optical design software is used for the analysis of the optical system design.
THE ANALYSIS ON SPACE RADIATION ENVIRONMENT AND EFFECT OF THE KOMPSAT-2 SPACECRAFT(I): TOTAL IONIZING DOSE EFFECT
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 153~162
In this paper, space radiation environment and total ionizing dose(TID) effect have been analyzed for the KOMPSAT-2 operational orbit. It has been revealed that the trapped protons are concentrated in the SAA(South Atlantic Anomaly) area and that the trapped protons and electrons, and solar protons are main factors affecting TID. It turned out that low energy Particles can be effectively blocked by aluminum shielding thickness, but high energy Particles can not be effectively blocked by increasing aluminum shielding thickness. KOMPSAT-2 total radiation dose which is accumulated continuously to spacecraft electronics has been expressed as the function of aluminum thickness. These values ran be used as the criteria for the selection of electronic parts and shielding thinkness of the KOMPSAT-2 structure or electronic box.
THE ANALYSIS ON SPACE RADIATION ENVIRONMENT AND EFFECT OF THE KOMPSAT-2 SPACECRAFT(II): SINGLE EVENT EFFECT
Journal of Astronomy and Space Sciences, volume 18, issue 2, 2001, Pages 163~173
In this paper, space radiation environment and single event effect(SEE) have been analyzed for the KOMPSAT-2 operational orbit. As spacecraft external and internal space environment, trapped proton, SEP(solar energetic particle) and GCR(galactic cosmic ray) high energy Protons and heavy ions spectrums are analyzed. Finally, SEU and SEL rate prediction has been performed for the Intel 80386 microprocessor CPU that is planned to be used in the KOMPSAT-2. As the estimation results, under nominal operational condition, it is predicted that trapped proton and high energetic proton induced SBU effect will not occur. But, it is predicted that heavy ion induced SEU can occur several times during KOMPSAT-2 3-year mission operation. KOMPSAT-2 has been implementing system level design to mitigate SEU occurrence using processor CPU error detection function of the on-board flight software.