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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 & Issues
Volume 22, Issue 4 - Dec 2005
Volume 22, Issue 3 - Sep 2005
Volume 22, Issue 2 - Jun 2005
Volume 22, Issue 1 - Mar 2005
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A SPECTROSCOPIC STUDY OF THE CLOSE BINARY AG VIRGINIS
Kim, Ho-Il ; Lee, Chung-Uk ; Lee, Jae-Woo ; Sohn, Mi-Rim ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 353~362
DOI : 10.5140/JASS.2005.22.4.353
We performed a new high-resolution spectroscopy of AG Vir for 4 nights from 25 March 2004 using the BOES (Bohyunsan Optical Echelle Spectrograph) attached to the 1.8-m reflector at Bohyunsan Optical Astronomy Observatory, and obtained a total of 59 spectra where all orbital phases are covered. To get the radial velocities of the binary system, both method of the CCF (Cross-Co..elation Function)and the BF (Broadening Function) were applied to the analysis of all the observed spectra. From these, the CCF could calculate the radial velocities of the primary star alone, while the BF could determine those of the primary and the secondary components. New absolute dimensions were deduced with the combination of our spectroscopic orbital elements ($K_1
DYNAMICAL SUBSTRUCTURES OF GALACTIC GLOBULAR CLUSTERS III. NGC 7006
Rhee, Jong-Hwan ; Sohn, Young-Jong ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 363~376
DOI : 10.5140/JASS.2005.22.4.363
To study the effects of giant population on dynamical substructures of the central region of NGC 7006, we examine the radial variations of ellipticity and position angle on By stellar photometry using ellipse fitting technique. Total variations of ellipticity and position angle lie in the range
, respectively, from the center out to three times the half light radius. Our ellipse fitting results, after removing giant populations, show that the apparent central dynamical substructures of NGC 7006 are mainly affected by red giant, horizontal branch stars. On the contrary, the contribution of light from subgiant stars to the inner dynamical substructure seems to be insignificant.
GAMMA-RAY BURST FORMATION ENVIRONMENT: COMPARISON OF REDSHIFT DISTRIBUTIONS OF GRB AFTERGLOWS
Kim, Sung-Eun ; Chang, Heon-Young ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 377~384
DOI : 10.5140/JASS.2005.22.4.377
Since gamma-ray bursts(GRBs) have been first known to science societites in 1973, many scientists are involved in their studies. Observations of GRB afterglows provide us with much information on the environment in which the observed GRBs are born. Study of GRB afterglows deals with longer timescale emissions in lower energy bands (e.g., months or even up to years) than prompt emissions in gamma-rays. Not all the bursts accompany afterglows in whole ranges of waveleogths. It has been suggested as a reason for that, for instance, that radio and/or X-ray afterglows are not recorded mainly due to lower sensitivity of detectors, and optical afterglows due to extinctions in intergalactic media or self-extinctions within a host galaxy itself. Based on the idea that these facts may also provide information on the GRE environment, we analyze statistical properties of GRB afterglows. We first select samples of the redshift-known GRBs according to the wavelength of afterglow they accompanied. We then compare their distributious as a function of redshift, using statistical methods. As a results, we find that the distribution of the GRBs with X-ray afterglows is consistent with that of the GRBs with optical afterglows. We, therefore, conclude that the lower detection rate of optical afterglows is not due to extinctions in intergalactic media.
AUTOMATED STREAK DETECTION FOR HIGH VELOCITY OBJECTS: TEST WITH YSTAR-NEOPAT IMAGES
Kim, Dae-Won ; Byun, Yong-Ik ; Kim, Su-Yong ; Kang, Yong-Woo ; Han, Won-Yong ; Moon, Hong-Kyu ; Yim, Hong-Suh ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 385~392
DOI : 10.5140/JASS.2005.22.4.385
We developed an algorithm to efficiently detect streaks in survey images and made a performance test with YSTAR-NEOPAT images obtained by the 0.5m telescope stationed in South Africa. Fast moving objects whose apparent speeds exceed 10 arcsec/min are the main target of our algorithm; these include artificial satellites, space debris, and very fast Near-Earth Objects. Our algorithm, based on the outline shape of elongated sources employs a step of image subtraction in order to reduce the confusion caused by dense distribution of faint stars. It takes less than a second to find and characterize streaks present in normal astronomical images of 2K format. Comparison with visual inspection proves the efficiency and completeness of our automated detection algorithm. When applied to about 7,000 time-series images from YSTAR telescope, nearly 700 incidents of streaks are detected. Fast moving objects are identified by the presence of matching streaks in adjoining frames. Nearly all of confirmed fast moving objects turn out to be artificial satellites or space debris. Majority of streaks are however meteors and cosmic ray hits, whose identity is often difficult to classify.
ALGORITHMS FOR MOVING OBJECT DETECTION: YSTAR-NEOPAT SURVEY PROGRAM
Bae, Young-Ho ; Byun, Yong-Ik ; Kang, Yong-Woo ; Park, Sun-Youp ; Oh, Se-Heon ; Yu, Seoung-Yeol ; Han, Won-Young ; Yim, Hong-Suh ; Moon, Hong-Kyu ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 393~408
DOI : 10.5140/JASS.2005.22.4.393
We developed and compared two automatic algorithms for moving object detections in the YSTAR-NEOPAT sky survey program. One method, called starlist comparison method, is to identify moving object candidates by comparing the photometry data tables from successive images. Another method, called image subtraction method, is to identify the candidates by subtracting one image from another which isolates sources moving against background stars. The efficiency and accuracy of these algorithms have been tested using actual survey data from the YSTAR-NEOPAT telescope system. For the detected candidates, we performed eyeball inspection of animated images to confirm validity of asteroid detections. Main conclusions include followings. First, the optical distortion in the YSTAR-NEOPAT wide-field images can be properly corrected by comparison with USNO-B1.0 catalog and the astrometric accuracy can be preserved at around 1.5 arcsec. Secondly, image subtraction provides more robust and accurate detection of moving objects. For two different thresholds of 2.0 and
, image subtraction method uncovered 34 and 12 candidates and most of them are confirmed to be real. Starlist comparison method detected many more candidates, 60 and 6 for each threshold level, but nearly half of them turned out to be false detections.
CORRELATION BETWEEN MONTHLY CUMULATIVE AURORAL ELECTROJET INDICES, DST INDEX AND INTERPLANETARY ELECTRIC FIELD DURING MAGNETIC STORMS
Park, Yoon-Kyung ; Ahn, Byung-Ho ; Moon, Ga-Hee ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 409~418
DOI : 10.5140/JASS.2005.22.4.409
Magnetospheric substorms occur frequently during magnetic storms, suggesting that the two phenomena are closely associated. We can investigate the relation between magnetospheric substorms and magnetic storms by examining the correlation between AE and Dst indices. For this purpose, we calculated the monthly cumulative AU,
indices. The correlation coefficient between the monthly cumulative
index is found to be 0.60, while that between monthly cumulative AU and
index is 0.28. This result indicates that substorms seem to contribute to the development of magnetic storms. On the other hand, it has been reported that the interplanetary electric field associated with southward IMF intensifies the magnetospheric convection, which injects charged particles into the inner magnetosphere, thus developing the ring current. To evaluate the contribution of the interplanetary electric field to the development of the storm time ring current belt, we compared the monthly cumulative interplanetary electric field and the monthly cumulative Dst index. The correlation coefficient between the two cumulative indices is 0.83 for southward IMP and 0.39 for northward IMF. It indicates that magnetospheric convection induced by southward IMF is also important in developing magnetic storms. Therefore, both magnetospheric substorm and enhanced magnetospheric convection seem to contribute to the buildup of magnetic storm.
A STATISTICAL ANALYSIS OF SOLAR WIND DYNAMIC PRESSURE PULSES DURING GEOMAGNETIC STORMS
Baek, J.H. ; Lee, D.Y. ; Kim, K.C. ; Choi, C.R. ; Moon, Y.J. ; Cho, K.S. ; Park, Y.D. ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 419~430
DOI : 10.5140/JASS.2005.22.4.419
We have carried out a statistical analysis on solar wind dynamic pressure pulses during geomagnetic storms. The Dst index was used to identify 111 geomagnetic storms that occurred in the time interval from 1997 through 2001. We have selected only the events having the minimum Dst value less than -50 nT. In order to identify the pressure impact precisely, we have used the horizontal component data of the magnetic field H (northward) at low latitudes as well as the solar wind pressure data themselves. Our analysis leads to the following results: (1) The enhancement of H due to a pressure pulse tends to be proportional to the magnitude of minimum Dst value; (2) The occurrence frequency of pressure pulses also increases with storm intensity. (3) For about
of our storms, the occurrence frequency of pressure pulses is greater than
, implying that to. those storms the pressure pulses occur more frequently than do periodic substorms with an average substorm duration of 2.5 hrs. In order to understand the origin of these pressure pulses, we have first examined responsible storm drivers. It turns out that
of the studied storms we driven by coronal mass ejections (CMEs) while others are associated with corotating interaction regions
or Type II bursts
. Out of the storms that are driven by CMEs, over
show that the main phase interval overlaps with the sheath, namely, the region between CME body and the shock, and with the leading region of a CME. This suggests that the origin of the frequent pressure pulses is often due to density fluctuations in the sheath region and the leading edge of the CME body.
NEAR REAL-TIME ESTIMATION OF GEOMAGNETIC LOCAL K INDEX FROM GYEONGZU MAGNETOMETER
Choi, K.C. ; Cho, K.S. ; Moon, Y.J. ; Kim, K.H. ; Lee, D.Y. ; Park, Y.D. ; Lim, M.T. ; Park, Y.S. ; Lim, H.R. ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 431~440
DOI : 10.5140/JASS.2005.22.4.431
Local K-index is an indicator representing local geomagnetic activity in every 3 hour. For estimation of the local K-index, a reasonable determination of solar quiet curve (undisturbed daily variation of geomagnetic field) is quiet essential. To derive the solar quiet curve, the FMI method, which is one of representative algorithms, uses horizontal components (H and D) of 3 days magnetometer data from the previous day to the next day for a specific day. However, this method is not applicable to real time forecast since it always requires the next day data. In this study, we have devised a new method to estimate local K-index in near real-time by modifying the FMI method. The new method selects a recent quiet day whose
indices, reported by NOAA/SEC are all lower than 3, and replace the previous day and the next day data by the recent quiet day data. We estimated 2,672 local K indices from Gyeongzu magnetometer in 2003, and then compared the indices with those from the conventional FMI method. We also compared the K indices with those from Kakioka observatory. As a result, we found that (1) K indices from the new method are nearly consistent with those of the conventional FMI method with a very high correlation (R
RESEARCH ON SPACE ENVIRONMENTAL EFFECT OF ORGANIC COMPOSITE MATERIALS FOR THERMAL MANAGEMENT OF SATELLITES USING MC-50 CYCLOTRON
Kim, Dae-Weon ; Kim, Dong-Iel ; Huh, Yong-Hak ; Yang, Tae-Keun ; Lee, Ho-Young ; Kim, Yong-Hyup ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 441~450
DOI : 10.5140/JASS.2005.22.4.441
The organic material is one of the most popular material for the satellites and the spacecrafts in order to perform the thermal management, and to protect direct exposure from the space environment. The present paper observes material property changes of organic material under the space environment by using ground facilities. One of the representative organic thermal management material of satellites, 2 mil ITO(Indium Tin Oxide) coated aluminized KAPTON was selected for experiments. In order to investigate the single parametric effect of protons in space environment, MC-50 cyclotron system in KIRAMS(Korea Institute of Radiological and Medical Science) was utilized for the ion beam irradiation of protons and ion beam dose was set to the Very Large August 1972 EVENT model, the highest protons occurrence near the earth orbit in history. The energy of ion beam is fixed to 30MeV(mesa electron volt), observed average energy, and the equivalent irradiance time conditions were set to 1-year, 3-year, 5-year and 10-year exposure in space. The procedure of analyses includes the measurement of the ultimate tensile strength for the assessment of quantitative degradation in material properties, and the imaging analyses of crystalline transformation and damages on the exposed surface by FE-SEM(Field Emission Scanning Electron Spectroscopy) etc.
OPTIMAL TRAJECTORY CORRECTION MANEUVER DESIGN USING THE B-PLANE TARGETING METHOD FOR FUTURE KOREAN MARS MISSIONS
Song, Young-Joo ; Park, Eun-Seo ; Yoo, Sung-Moon ; Park, Sang-Young ; Choi, Kyu-Hong ; Yoon, Jae-Cheol ; Yim, Jo-Ryeong ; Choi, Joon-Min ; Kim, Byung-Kyo ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 451~462
DOI : 10.5140/JASS.2005.22.4.451
Optimal Trajectory Correction Maneuver (TCM) design algorithm has been developed using the B-plane targeting method for future Korean Mars missions. For every-mission phase, trajectory informations can also be obtained using this developed algorithms which are essential to design optimal TCM strategy. The information were computed under minimum requiring perturbations to design Mars missions. Spacecraft can not be reached at designed aim point because of unexpected trajectory errors, caused by many perturbations and errors due to operating impulsive maneuvers during the cruising phase of missions. To maintain spacecraft`s appropriate trajectory and deliver it to the designed aim point, B-plane targeting techniques are needed. A software NPSOL is used to solve this optimization problem, with the performance index of minimizing total amount of TCM`s magnitude. And also executing time of maneuvers on be controlled for the user defined maneuver number
of TCMs. The constraints, the Mars arrival B-plane boundary conditions, are formulated for the problem. Results of this work show the ability to design and analyze overall Mars missions, from the Earth launch phase to Mars arrival phase including capture orbit status for future Korean Mars missions.
DYNAMIC MODEL DEVELOPMENT FOR INTERPLANETARY NAVIGATION
Park, Eun-Seo ; Song, Young-Joo ; Yoo, Sung-Moon ; Park, Sang-Young ; Choi, Kyu-Hong ; Yoon, Jae-Cheol ; Yim, Jo-Ryeong ; Choi, Joon-Min ; Kim, Byung-Kyo ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 463~472
DOI : 10.5140/JASS.2005.22.4.463
In this paper, the dynamic model development for interplanetary navigation has been discussed. The Cowell method for special perturbation theories was employed to develop an interplanetary trajectory propagator including the perturbations due to geopotential, the Earth`s dynamic polar motion, the gravity of the Sun, the Moon and the other planets in the solar system, the relativistic effect of the Sun, solar radiation pressure, and atmospheric drag. The equations of motion in dynamic model were numerically integrated using Adams-Cowell 11th order predictor-corrector method. To compare the influences of each perturbation, trajectory propagation was performed using initial transfer orbit elements of the Mars Express mission launched in 2003, because it can be the criterion to choose proper perturbation models for navigation upon required accuracy. To investigate the performance of dynamic model developed, it was tested whether the spacecraft can reach the Mars. The interplanetary navigation tool developed in this study demonstrated the spacecraft entering the Mars SOI(Sphere of Influence) and its velocity .elative to the Mars was less than the escape velocity of the Mars, hence, the spacecraft can arrive at the target planet. The obtained results were also verified by using the AGI Satellite Tool Kit. It is concluded that the developed program is suitable for supporting interplanetary spacecraft mission for a future Korean Mars mission.
DESIGN OF THE OPTICAL SYSTEM FOR A PROTOMODEL OF SPACE INFRARED CRYOGENIC SYSTEM
Lee, Dae-Hee ; Pak, Soo-Jong ; Yuk, In-Soo ; Nam, Uk-Won ; Jin, Ho ; Lee, Sung-Ho ; Han, Jeong-Yeol ; Yang, Hyung-Suk ; Kim, Dong-Lak ; Kim, Geon-Hee ; Park, Seong-Je ; Kim, Byung-Hyuk ; Jeong, Han ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 473~482
DOI : 10.5140/JASS.2005.22.4.473
Many technical challenges are being tried for a large space infrared telescope, which is one of the major objectives of the Strategic Technology Road Map (STRM) of KASI (Korea Astronomy and Space Science Institute), As one of these challenges, KASI and KBSI (Korea Basic Science Institute) have started a cooperation project for developing a space infrared cryogenic system with KIMM (Korea Institute of Machinery as Materials) and i3system co. In this paper, we generate optical requirements for the Protomodel of Space Infrared Cryogenic System (PSICS), and design a single lens optical system with a bandpass of
, a field of view of
, and an angular resolution of
, to develop a further complex optical system.
A STUDY OF RESIDUAL IMAGE IN CHARGED-COUPLED DEVICE
Jin, Ho ; Lee, C.U. ; Kim, S.L. ; Kang, Y.B. ; Goo, J.L. ; Han, W. ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 483~490
DOI : 10.5140/JASS.2005.22.4.483
For an image sensor CCD, electrons can be trapped at the front-side
surface interface in a case of exceeding the full well by bright source. Residual images can be made by the electrons remaining in the interface. These residual images are seen in the font-side-illuminated CCDs especially. It is not easy to find a quantitative analysis for this phenomenon in the domestic reports, although it is able to contaminate observation data. In this study, we find residual images iB dark frames which were obtained from the front-side-illuminated CCD at Mt. Lemmon Optical Astronomy Observatory (LOAO), and analyze the effect to contaminated observation data by residual charges.
DETERMINATION OF CLOCK OFFSET USING GPS CARRIER PHASE MEASUREMENTS
Ha, Ji-Hyun ; Park, Kwan-Dong ; Lee, Chang-Bok ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 491~500
DOI : 10.5140/JASS.2005.22.4.491
Every time laboratory in the world follows an international standard time scale and GPS (Global Positioning System) is playing an important role. Korea Research Institute of Standards and Science is also operating a permanent GPS station for time transfer. To improve the accuracy and precision of the clock offsets derived from GPS we used carrier phase measurements. In addition, we tested four different kinds of GPS satellite orbits and compared the results. The precision of the time offsets using rapid and ultra-rapid orbits was about 0.5 nanoseconds (ns). Tn the case of broadcast orbits, the precision was better than 2 ns.
REAL-TIME TRAJECTORY ESTIMATION OF SPACE LAUNCH VEHICLE USING EXTENDED KALMAN FILTER AND UNSCENTED KALMAN FILTER
Baek, Jeong-Ho ; Park, Sang-Young ; Park, Eun-Seo ; Choi, Kyu-Hong ; Lim, Hyung-Chul ; Park, Jong-Uk ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 501~512
DOI : 10.5140/JASS.2005.22.4.501
This research supposed when a fictitious KSIV-I space launch vehicle launches from NARO space center. This compared and analyzed the results from real-time trajectory estimation using the Extended Kalman Filter and the Unscented Kalman Filter. A virtual trajectory and observation data are generated for the fictitious KSLV-I and three measurement radars. The performances of both Otters are compared for several simulations with small initial errors, large initial errors, 20Hz and 10Hz data rate. The results show that the Unscented Kalman Filter yields faster convergence and more accurate than the Extended Kalman Filter for the cases with larger initial error and slower data rate conditions.
DTERMINATION OF STBLE-UNSTABLE REGIONS OF THE SLOSH MOTION IN SPINNING SPACE VEHICLE BY PERTURBATION TECHNIQUE
Kang, Ja-Young ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 513~526
DOI : 10.5140/JASS.2005.22.4.513
The objectives of this study are to perform extensive analysis on internal mass motion for a wider parameter space and to provide suitable design criteria for a broader applicability for the class of spinning space vehicles. In order to examine the stability criterion determined by a perturbation method, some numerical simulations will be performed and compared at various parameter points. In this paper, Ince-Strutt diagram for determination of stable-unstable regions of the internal mass motion of the spinning thrusting space vehicle in terms of design parameters will be obtained by an analytical method. Also, phase trajectories of the motion will be obtained for various parameter values and their characteristics are compared.
ANALYSIS OF COMS-1 NORTH-SOUTH STATION KEEPING METHOD
Kim, Hae-Yeon ; Lee, Byoung-Sun ; Hwang, Yoo-La ; Kim, Young-Rok ; Park, Sang-Young ; Kim, Jae-Hoon ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 527~536
DOI : 10.5140/JASS.2005.22.4.527
The perturbations caused by the Sun and the Moon are predominantly out-of-plane effects causing a change in the inclination and in the right ascension of ascending node of a geostationary satellite. Due to the change of the inclination, subsatellite latitude of the geostationary satellite has a daily variations of the same magnitude of the inclination. Therefore we need a facility to control the orbital inclination and right ascension of ascending node for maintaining the satellite position in specified subsatellite latitude boundary using thrusters. In this paper we studied North-South station keeping strategies of the COMS-1 such as Track-Back Chord Target (TBCT) method, Maximum Compensation Target (MCT) method and Minimum Fuel Target (MFT) method. We accomplished those North-South station keeping maneuvers for one year starting from December 2008. The required velocity increments to maintain the satellite are estimated as MCT 52.6065m/s, TBCT 52.2383m/s, MFT 51.5428m/s, respectively. We demonstrated that TBCT and MFT methods are proper to North-South station keeping for COMS-1. MFT method showed the minimum required velocity increments whereas TBCT traced narrow inclination boundary area for North-South station keeping.
HAUSAT-2 SATELLITE RADIATION ENVIRONMENT ANALYSIS AND SOFTWARE RAMMING CODE EDAC IMPLEMENTATION
Jung, Ji-Wan ; Chang, Young-Keun ;
Journal of Astronomy and Space Sciences, volume 22, issue 4, 2005, Pages 537~558
DOI : 10.5140/JASS.2005.22.4.537
This paper addresses the results of HAUSAT-2 radiation environment and effect analyses, including TID and SEE analyses. Trapped proton and electron, solar proton, galactic cosmic ray models were considered for HAUSAT-2 TID radiation environment analysis. TID was analyzed through total dose-depth curve and the radiation tolerance of TID for HAUSAT-2 components was verified by using DMBP method and sectoring analysis. HAUSAT-2 LET spectrum for heavy ion and proton were also analyzed for SEE investigation. SEE(SEU, SEL) analyses were accomplished for MPC860T2B microprocessor and K6X8008T2B memory. It was estimated that several SEUs may occur without SEL during the HAUSAT-2 mission life(2 years). Software Hamming Code EDAC has been implemented to detect and correct the SEU. In this study, all radiation analyses were conducted by using SPENVIS software.