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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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The Korean Space Science Society
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Volume 15, Issue 2 - Dec 1998
Volume 15, Issue 1 - Jun 1998
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학술지 논문투고 및 논문양식 : 새로운 규정에 대한 안내
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 269~276
BV STELLAR PHOTOMETRY OF 23 GALACTIC GLOBULAR CLUSTERS
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 277~289
We report V-(B - V) CCD Color Magnitude Diagrams (CMDs) for 23 southern Galactic globular clusters. Limiting magnitudes for each cluster are between 18 and 20 magnitudes in V. Most CMDs show subgiant starts, red giant stars, and horizontal branch stars. From the CMDs, we have determined the horizontal branch magnitudes, V(HB), reddenings, E(B - V), and distances of each cluster.
MODELS FOR THE IRAS LOW RESOLUTION SPECTRA OF OH/IR STARS
Lee, Sung-Min ; Suh, Kyung-Won ;
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 291~295
We investigate models for the IRAS LRS)Low Resolution Spectra) of OH/IR stars. OH/IR stars often show the silicate features at 9.7
in the spectra obtained by the IRAS LRS as well as remarkably red values in the IRAS photometric colors such as - and -. We compare the radiative transfer model results with observed spectral energy distributions (SEDs) of the stars including IRAS PSC(Point Source Catalog), IRAS LRS and ground based observational data.
PHOTOELECTRIC OBSERVATIONS AND PERIOD STUDY OF ECLIPSING BINARY VZ CEP
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 297~306
Photoelectric observations of the neglected eclipsing binary VZ Cep were made on four night during the observing season of 1984 at Sobaeksan Astronomy Observatory. The UBV light curves were secured incompletely with the gap in 0.35-0.75 phases. From the observations three times of minimum lights were determined in three band-passes, which formed one weighted minimum epoch (JD Hel 2446009.0453). With our observations, and improved light elements for VZ Cep is determined using all the photoelectric and CCD times of minimum lights published so far. The (O-C) resid-uals calculated with our light elements show small varying scatters which cannot be negligible. From the analyses of all the times of minima with the Scargle’s(1982)period-searching and a curve fitting methods, we found possible periodic oscillations of the (O-C) residuals with the period of 1. y26 and the amplitude of 0.d0032. These results, however, have to be considered as a preliminary values until complete analysis for the minimum lights of VZ Cep with enough observational data. Future observations of this binary system are urgently prompted.
PROPAGATION OF CME IN MULTI-SATELLITE OBSERVATIONS
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 307~320
We investigate the propagation of Coronal Mass Ejections(CMEs) near the earth with multi-satellite observations. Among the CMEs observed in the near-earth between Nov. 1994 and Nov. 1997, we select two events of Jan. 6-11,1997 and Nov. 4-7, 1997 which were observed by more than 3 satellites when these satellites were located apart with a sufficient distance from each other. We determine the speed and propagation of the two CMEs by calculating the position of each satellite in various coordinates and the onset time of each event. The results show that the speed of CMEs becomes significantly reduced when the perturbation arrives in the magnetosphere. It is also suggested that the propagation of the CMEs is approximated as the -x direction in GSE coordinates in the near-earth space.
THE STELLAR COLOR-TEMPERATURE RELATION IN ULTRAVIOLET REGION
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 321~333
In order to derive the UV color - effective temperature relation, we calculated the effective temperature and ultraviolet color index for about 118 IUE standard stars. Using differential correction method, the effective temperature was obtained by the best fittings of IUE low-dispersion spectra to the Kurucz model (1993), and the UV color index was calculated from the magnitude differences of the UV wavelength between 2750
. The temperature determined by the Kurucz model fittings was consistent with that obtained by other investigators (Malagnini & Morossi 1990, Malagnini et al. 1986), except for the low temperature stars. The relations between UV color - effective temperature also was similar to that in Kurucz model.
UV LINE EMISSIONS OF 44i BOOTIS
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 335~340
We obtained UV light curves of 44i Bootis, a W UMa type star from the IUE low dispersion spectra. In order to investigate variations of the emission lines from chromospheric activity and transition region, UV line intensity has been measured for CI, CII, ClV, SiIV, HeII lines. Through plotting the line intensity with the orbital phase, we found that emission lines showed maximum at
of the light curves, indicating the chromospheric activity of contact binary, 44i Bootis. We found that the light curves of UV emission lines is strongly modulated by the variation of chromospheric activities of 44i Bootis
A MONTE CARLO SIMULATION FOR THE X-RAY DETECTION EFFICIENCY OF A MULTI-CELL PROPORTIONAL COUNTER
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 341~358
The X-ray astronomy team of the Korea Astronomy Observatory(KAO) is planning to develop a multi-cell proportional counter, adopting an anti-coincidence method to reduce its internal background. We have developed a Monte Carlo code to determine the X-ray detection efficiency of the counter. As a check of our code, we successfully reproduced the detection efficiency of Ginga/LAC. In this paper, we report the simulation results for the counter being considered in KAO.
OPTICAL DESIGN OF THE FAR ULTRAVIOLET IMAGING SPECTROGRAPH
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 359~371
We present the design specifications and the performance estimation of the FUVS (Far Ultraviolet Spectrograph) proposed for the observations of aurora, day/night airglow and astronomical objects on small satelltes in the spectral range of
. The design of FUVS is carried out with the full consideration of optical characteristics of the grating and the aspheric substrate. Two independent methods, ray-tracing and the wave front aberration theory, are employed to estimate the performance of the optical design and it is verified that both procedures yield the resolution of
in the entire spectral range. MDF (Minimum Detectable Flux) is also estimated using the known characteristics of the reflecting material and MCP, to study the feasibility of detection for faint emission lines from the hot interstellar plasmas. The results give that the observations from 1 day to 1 week, depending on the line intensity, can detect such faint emission lines from diffuse interstellar plasmas.
AN X-RAY EXPERIMENT WITH TWO-STAGE KOREAN SOUNDING ROCKET
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 373~389
The test result of the X-ray observation system is presented which have been developed at Korea Astronomy Observatory for 3 years(1995 -1997). The instrument, which is composed of detector and signal processing parts, is designed for the future observations of compact X-ray sources. The performance of the instrument was tested by mounting on the two-stage Korean Sounding Rocket, which was launched from Taean rocket flight center on June 11 at 10:00 KST 1998. Telemetry data was received from individual parts of the instrument for 32 and 55.7 sec, respectively, since the launch of the rocket. In this paper, the result of the data analysis based on the received telemetry data and discussion about the performance of the instrument is reported.
ROCKET MEASUREMENT OF MIDDLE ATMOSPHERIC OZONE CONCENTRATION PROFILE BY KSR-II
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 391~400
KSR-II, a two-stage sounding rocket of KARI was launched successfully at the west coast of the Korean Peninsula at 1000LST, June 11, 1998. For the ozone measurement mission, 8-channel UV and visible radiometers were onboard the rocket. The rocket measured the first in situ stratospheric and mesospheric ozone density profile over Korea during its ascending phase using the radiometer. Comparisons with Dobson spectrophotometer, ozonesonde, and HALOE onboard the UARS are shown together. Our results are in reasonable agreements with others.
A STUDY OF THE IONOSPHERIC ELECTRON MEASUREMENT ON THE MEDIUM-SIZED SCIENTIFIC ROCKET , KSR-II
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 401~415
This paper reports the results obtained from the Langmuir probe (LP) and Electron Temperature Probe (ETP) experiments on the sounding rocket KSR-II (Korean Scientific Rocket - II) which was launched on Jun 11, 1998 at 10:00 KST from Tae-An peninsula (37
E). The instruments successfully measured the electron density, electron temperature, and the floating potential at altitudes of 73km to 130km. While the electron temperature measurement is not easy in this region, since the temperature is very low and the contamination effect of the probe may give rise to a problem, we were able to obtain a reasonable electron temperature profile by employing two independent methods, the pulse modulated Langmuir Probe and Electron Temperature Probe. The preliminary results show that electron density increases sharply at about 90km, and forms a peak at 102km. The density profile is roughly consistent with IRI (International Reference Ionosphere)95-model or PIM (Parameterized Ionospheric Model) results except that the peak density appears at 110km in the model and model electron density is slightly lower than the observed one. Electron temperature obtained from ETP fluctuates between 200
K and 700
K, an effect presumably coming from the wakes developed by LP, and it tends to increase with the altitude, which is consistent with the LP results.
MONTE CARLO ANALYSIS FOR FIRST ACQUISITION AND TRACKING OF THE KOMPSAT SPACECRAFT
Lee, Byeong-Seon ; Lee, Jeong-Sook ;
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 417~425
Monte Carlo analysis is performed for the first acquisition and tracking of the KOMP-SAT spacecrat in GSOC tracking station after separation from Taurus launch vehicle. The error bounds in position and velocity vector in Earth-fixed coordinate system at injection point are assumed based on the previous launch mission. Ten thousands injection orbital elements with normal distribution are generated and propagated for Monte Carlo analysis. The tracking antenna pointing errors at spacecraft rising time and closest approach time at German Space Operations Center(GSOC) Weiheim track-ing station are derived. Then the tracking antenna scanning angles are analyzed for acquisition and tracking of the KOMPSAT signal.
LIQUID APOGEE ENGINE BURN PLANS FOR THE KOREASAT-3
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 427~436
The apogee manoeuvre of
is basic elliptical orbit transfer converting orbit plane. The KOREASAT-3 is planed for multi-burn manoeuvres using the liquid apogee engine while the
used the apogee kick motor that executes a single burn in the apogee of transfer orbit using the solid propellant. This study analyzed the multi-burn manoeuvres using the liquid apogee engine and the propellant control method and developed the simulation tools. For the purpose of precise simulation, We designed tools in the basic of orbit propagation software, COWELL5, that was developed by members of Center for Astrodynamics in Yonsei university and the results can be displayed in 3-D graphic of
Orbit Determination Error Analysis for the KOMPSAT
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 437~447
Orbit error analysis was performed for the GPS navigation solutions and ground station tracking data of the KOMPSAT (Korea Multi-Purpose SATellite), which will be launched in 1999 for cartography of Korean peninsula as main mission. A least square method was used for the orbit determination and prediction error simulation including tracking data noises and dynamic modeling errors. It was found that a short-term periodic orbit determination error was caused by the tracking data noise and dominant orbit prediction error was caused by solar flux uncertainty.
LUNAR ECLIPSE ANALYSIS FOR KOMPSAT
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 449~458
The Korea Muliti-Purpose Satellite(KOMPSAT) uses a sun-synchronous orbit with an altitude 685km as mission orbit and undergoes earth eclipses and infrequently lunar eclipses. Lunar eclipses occur when the moon is located between the sun and the satellite and blocks partially or fully the sunlight. The eclipse causes the satellite to increase battery discharge times and affects satellite lifetime and mission operation. The KOMPSAT lunar eclipses can cause additional effects to energy balance and battery disc of the KOMPSAT lunar eclipse for 3 year mission lifetime. Also mission planning scenario is presented for lunar eclipses at the KOMPSAT Grouns Station(KGS).
STUDY ON KOMPSAT SATELLITE MISSION LIFETIME FACTORS
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 459~473
As the satellite system becomes more complex, the probability of unpredictable failures may be increased due to design inadequacy, experience deficiency, lack of problem recognition. Poor quality control, improper testing, and workmanship fault. Consequently, these problems can lead to the reduction or end of the satellite mission lifetime. This article addresses general satellite failure modes and factors influencing satellite mission life. The mission life factors of LEO sun-synchronous KOMPSAT spacecraft are investigated, in which its mission life is predicted based on these factors. Since the end of mission due to random failures is not predictable, the predictable mission life factors such as power budget, propellant budget, battery charging/discharging cycle, radiation effects payload reliability, single point failure, and redundancy are primarily investigated.
A Study on an Object oriented Modeling for the Satelite Control System Development reusing Structured Analysis and Design Approach
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 475~484
The object-oriented approach is a difficult method for engineers who are accustomed to other software development methods although it is an excellent software development approach. This paper presents a method for object-orineted modeling re-using DFD(Data Flow Diagram) and SC(Structure Chart) of structured analysis and design approach. This paper suggests an easy method for analysis and design using structured approach for object abstraction, which is one of the most difficult things in object-oriented approach.
ANALYTICAL STUDY ON MISSION CONTROL ELEMENT SYSTEM AVAILABILITY FOR KOREA MULTIPURPOSE SATELLITE(KOMPSAT)I
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 485~497
To estimate the availability of the MCE for KOMPSAT I, mathematical models of H/W and S/W availability, the availability estimating methods for parallel and redundant system were presented. Furthermore, to improve and estimate the MCE system availability, we analyzed the computational procedure of redundant methods, and we also included effective switch choosing methods in this paper. The analytical results of the MCE system availability were estimated as follows: - 0.995216 not considering system redundancy, - 0.9955165 considering system redundancy, and -0.9963991 for the time of system real time operation.
DESIGN OF SATELLITE OPERATIONS SUBSYSTEM USING DYNAMIC FAULT MANAGEMENT MECHNAISM
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 499~508
Satellite Operations Subsystem in the Mission Control Element provides real-time monitoring of the satellite status and transmits telecommands to control the satellite during the contact time. This paper presents the dynamic fault management strategy of Satellite Operations Subsystem designed to minimize data loss using software and hardware redundancy for upgrade safety and reliability of Satellite Operations Subsystem. Also this paper describes the performance test method to prove justification of implementation and analyzes the results.
MECHANICAL DESIGN OF MILITARY COMMUNICATION SATELLITE X-BAND PCM
Journal of Astronomy and Space Sciences, volume 15, issue 2, 1998, Pages 509~523
Before an actual military communications satellite is designed and constructed, a feasibility study should take place. The basic functions of such system can be observed and demonstrated in an X-Band payload simulator. For this purpose a Payload Concept Model (PCM) for X-Band payload subsystem has been developed to simulate the workings of an actual military communications payload. This paper explains and illustrates the mechanical design, manufacture, and integration of the PCM. Basic RF tests also have been performed in order to verify the design requirement of the system. The results demonstrate successful development of the PCM and operation without RF losses.