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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 26, Issue 4 - Dec 2009
Volume 26, Issue 3 - Sep 2009
Volume 26, Issue 2 - Jun 2009
Volume 26, Issue 1 - Mar 2009
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Magnitudes of the Red Giant Branch Tip and the Distance Moduli of Nearby Dwarf Galaxy NGC 205
Jung, M.Y. ; Chun, S.H. ; Chang, C.R. ; Han, M. ; Lim, D. ; Han, W. ; Sohn, Y.J. ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 417~420
DOI : 10.5140/JASS.2009.26.4.417
We have used the near-infrared
photometric data of resolved stars in a nearby dwarf elliptical galaxy NGC 205 to determine the magnitudes of the red giant branch tip (TRGB). By applying Savitzky-Golay filter to the observed luminosity functions (LFs) in each band, we derived the second derivatives of the LFs so as to determine the magnitudes of the TRGB. Absolute magnitudes of the TRGB in
bands were measured from the Yonsei-Yale isochrones. By comparing the determined apparent magnitudes and the theoretical absolute magnitudes of the TRGB, we estimated the distance moduli of NGC 205 to be (m - M) =
in J, H, and
Near-IR TRGB Distance Modulus of Dwarf Irregular Galaxy IC 1613
Jung, M.Y. ; Chun, S.H. ; Chang, C.R. ; Han, M. ; Lim, D. ; Han, W. ; Sohn, Y.J. ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 421~424
DOI : 10.5140/JASS.2009.26.4.421
magnitudes of the red giant branch tip (TRGB) and the distance moduli of the nearby dwarf irregular galaxy IC 1613 have been determined from the near-infrared luminosity functions (LFs) of the resolved stars in the galaxy. Applying a Savitzky-Golay filtering, we derived the second derivatives of the LFs, and estimated the apparent magnitudes of the TRGB as
. The mean values of the theoretical absolute magnitudes of the TRGB were measured by using the Yonsei-Yale isochrones with a metallicity range of -2.1 < [Fe/H] < -0.5 and age of 12 Gyr. The derived values of near-infrared TRGB distance moduli for IC 1613 are (m - M) =
for J, H, and
Dst Prediction Based on Solar Wind Parameters
Park, Yoon-Kyung ; Ahn, Byung-Ho ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 425~438
DOI : 10.5140/JASS.2009.26.4.425
We reevaluate the Burton equation (Burton et al. 1975) of predicting Dst index using high quality hourly solar wind data supplied by the ACE satellite for the period from 1998 to 2006. Sixty magnetic storms with monotonously decreasing main phase are selected. In order to determine the injection term (Q) and the decay time (
) of the equation, we examine the relationships between
during the magnetic storms. For this analysis, we take into account one hour of the propagation time from the ACE satellite to the magnetopause, and a half hour of the response time of the magnetosphere/ring current to he solar wind forcing. The injection term is found to be
> 0.5mV/m and Q(nT=h) = 0 for
(hour) is estimated as
> -175nT and 6.15 hours for
. Based on these empirical relationships, we predict the 60 magnetic storms and find that the correlation coefficient between the observed and predicted
is 0.88. To evaluate the performance of our prediction scheme, the 60 magnetic storms are predicted again using the models by Burton et al. (1975) and O'Brien & McPherron (2000a). The correlation coefficients thus obtained are 0.85, the same value for both of the two models. In this respect, our model is slightly improved over the other two models as far as the correlation coefficients is concerned. Particularly our model does a better job than the other two models in predicting intense magnetic storms (
Geosynchronous Relativistic Electron Events Associated with High-Speed Solar Wind Streams in 2006
Lee, Sung-Eun ; Hwang, Jung-A ; Lee, Jae-Jin ; Cho, Kyung-Suk ; Kim, Khan-Hyuk ; Yi, Yu ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 439~450
DOI : 10.5140/JASS.2009.26.4.439
Recurrent enhancements of relativistic electron events at geosynchronous orbit (GREEs) were observed in 2006. These GREE enhancements were associated with high-speed solar wind streams coming from the same coronal hole. For the first six months of 2006, the occurrence of GREEs has 27 day periodicity and the GREEs were enhanced with various flux levels. Several factors have been studied to be related to GREEs: (1) High speed stream, (2) Pc5 ULF wave activity, (3) Southward IMF Bz, (4) substorm occurrence, (5) Whistler mode chorus wave, and (6) Dynamic pressure. In this paper, we have examined the effectiveness about those parameters in selected periods.
Some Statistical Characteristics of Substorms Under Northward IMF Conditions
Lee, Ji-Hee ; Lee, D.Y. ; Choi, K.C. ; Jeong, Y. ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 451~466
DOI : 10.5140/JASS.2009.26.4.451
While substorms are known to generally occur under southward IMF conditions, they can sometimes occur even under northward IMF conditions. In this paper, we studied the substorms that occurred in May, 2000 to 2002 to examine some statistical characteristics of the IMF and solar wind associated with northward IMF substorms. We focused on the cases where two or more substorms occurred successively under northward IMF conditions. Also, by checking Sym-H index associated with each of the substorms we determined whether or not there is any association of such northward IMF substorm occurrence with storm times. We also examined statistical properties at geosynchronous altitude in terms of magnetic field dipolarization and energetic particle injection. The following results were obtained. (i) Most of the northward IMF substorms occurred under average solar wind conditions. The majority of them occurred within 2 hrs duration of northward IMF Bz state, but there are also a nonnegligible number of substorms that occurred after a longer duraiton of northward IMF Bz state. (ii) While most of the substorms occurred as isolated from a magnetic storm time, those that occurred in a magnetic storm time show a higher average value of IMF and solar wind than that for the isolated substorms. (iii) About 55% of the substorms were associated with the IMF clock angle that can possibly allow dayside reconnection, and the other 45% were associated with more or less pure northward IMF conditions. Therefore, for the latter cases, the energy input from the solar wind into the magnetosphere should be made by other way than the dayside reconnection. (iv) For most of the substorms, the magnetic field dipolarizations and energetic particle injections at geosynchronous altitude were identified to be generally weak. But, several events indicated strong magnetic field dipolarizations and energetic particle injections.
Ionospheric Behaviors Over Korea Peninsula During the Super Geomagnetic Storm Using GPS Measurements
Chung, Jong-Kyun ; Choi, Byung-Kyu ; Baek, Jung-Ho ; Jee, Geon-Hwa ; Cho, Jung-Ho ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 467~478
DOI : 10.5140/JASS.2009.26.4.467
The super-geomagnetic storms called 2003 Halloween event globally occurred during the period of 29 through 31 which are the following days when the solar flares of X18 class exploded on 28 October 2003. The S4 index from GPS signal strength and the peak electron density (
) from GPS tomography method are analyzed according to the date. The occurrences of the cycle slip and scintillation in the GPS signals are 1,094 and 1,387 on 28 and 29 October, respectively and these values are higher than 604 and 897 on 30 and 31 October. These mean the ionospheric disturbances are not always generated by the period of geomagnetic storm. Therefore, GPS S4 index is useful to monitor the ionospheric disturbances. Behaviors of ionospheric electron density estimated from GPS tomography method are analyzed with the date. At UT = 18 hr, the maximum
is shown on 28 October. It agrees with
variation measured from Anyang ionosonde, and the GPS signal are better condition on 30 and 31 October than 28 October. In conclusion, GPS signal condition is relation with geomagnetic activities, and depend upon the variation of the electron density. We will study the long-term data to examine the relationship between the GPS signal quality and the electron density as the further works.
Relationship Between Solar Proton Events and Corona Mass Ejection Over the Solar Cycle 23
Hwang, Jung-A ; Lee, Jae-Jin ; Kim, Yeon-Han ; Cho, Kyung-Suk ; Kim, Rok-Sun ; Moon, Yong-Jae ; Park, Young-Deuk ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 479~486
DOI : 10.5140/JASS.2009.26.4.479
We studied the solar proton events (SPEs) associated with coronal mass ejections (CMEs) during the solar cycle 23 (1997-2006). Using 63 SPE dataset, we investigated the relationship among SPE, flare, and CME, and found that (1) SPE rise time and duration time depend on CME speed and the earthward direction parameter of the CME, and (2) the SPE peak intensity depends on CME speed and X-ray Flare intensity. While inspecting the relation between SPE peak intensity and the direction parameter, we found there are two groups: first group consists of large six SPEs (> 10,000 pfu at > 10 MeV proton channel of GOES satellite) and shows strong correlation (cc = 0.65) between SPE peak intensity and CME direction parameter. The second group has a weak intensity and shows poor correlation between SPE peak intensity and the direction parameter (cc = 0.01). By investigating characteristics of the first group, we found that all the SPEs are associated with very fast halo CME (> 1400km/s) and also they are mostly located at central region and within
Study of Unidentified Spectral Lines in the High-Resolution Spectra of Comet Machholz (C/2004Q2)
Hwang, Sung-Won ; Han, Je-Hee ; Sim, Chae-Kyung ; Kim, Sang-Joon ; Jin, Ho ; Im, Myung-Shin ; Kim, Kang-Min ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 487~498
DOI : 10.5140/JASS.2009.26.4.487
We observed Comet Machholz (C/2004Q2) using the BOES (BOao Echelle Spectograph) at the Bohyunsan Observatory on January 4, 2005. We have studied a wavelength range of
in order to investigate unidentified spectral lines in the high-resolution spectra of Machholz. We compared the Machholz spectra with the high-resolution spectra of previous comets: Swift-Tuttle, Brorsen-Metcalf, Austin, and 122P/de Vico. We identified many molecular lines, which are previously unknown; and these identifications will be useful information for studying high-resolution spectra of future comets.
The Effect of Equatorial Spread F on Relative Orbit Determination of GRACE Using Differenced GPS Observations
Roh, Kyoung-Min ; Luehr, Hermann ; Park, Sang-Young ; Cho, Jung-Ho ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 499~510
DOI : 10.5140/JASS.2009.26.4.499
In this paper, relative orbit of Low Earth Orbit satellites is determined using only GPS measurements and the effects of Equatorial Spread-F (ESF), that is one of biggest ionospheric irregularities, are investigated. First, relative orbit determiation process is constructed based on doubly differenced GPS observations. In order to see orbit determination performance, relative orbit of two GRACE satellites is estimated for one month in 2004 when no ESF is observed. The root mean square of the achieved baselines compared with that from K-Band Ranger sensor is about 2~3 mm and average of 95% of ambiguities are resolved. Based on this performance, the relative orbit is estimated for two weeks of two difference years, 2003 when there are lots of ESF occurred, and 2004 when only few ESF occurred. For 2003, the averaged baseline error over two weeks is about 15 mm. That is about 4 times larger than the case of 2004 (3.6 mm). Ionospheric status achieved from K-Band Ranging sensor also shows that more Equatorial Spread-F occurred at 2003 than 2004. Investigation on raw observations and screening process revealed that the ionospheric irregualarities caused by Equatorial Spread-F gave significant effects on GPS signal like signal loss or enhancement ionospheric error, From this study, relative orbit determination using GPS observations should consider the effect of Equatorial Spread-F and adjust orbit determination strategy, especially at the time of solar maximum.
Detection of Ocean Tide Loading Constituents Based on Precise Point Positioning by GPS
Won, Ji-Hye ; Park, Kwan-Dong ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 511~520
DOI : 10.5140/JASS.2009.26.4.511
In this study, the Ocean Tide Loading (OTL) constituents were detected by the Precise Point Positioning (PPP) technique using GPS. Then, the GPS estimates of OTL constituents were compared with the predictions of the ocean tide models. We picked three permanent GPS stations as test sites and they are ICNW, SEOS, and CJUN. To detect the OTL constituents using GPS, we created vertical coordinate time series at 10-minute intervals using the PPP approach implemented in the GIPSY software. Through the tidal harmonic analysis of this height time series, the four major constituents (
) were determined. The amplitude obtained from the GPS height time series of the OTL constituents showed best match with the model predictions at CJUN, while the phase showed closest match at ICNW. The amplitude accuracy of the
, which is the dominant factor out of the 11 major constituents, was 24.8% on average.
Analysis on Space Environment from the Anomalies of Geosynchronous Satellites
Lee, Jae-Jin ; Hwang, Jung-A ; Bong, Su-Chan ; Choi, Ho-Sung ; Cho, Il-Hynn ; Cho, Kyung-Suk ; Park, Young-Deuk ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 521~528
DOI : 10.5140/JASS.2009.26.4.521
While it is well known that space environment can produce spacecraft anomaly, defining space environment effects for each anomalies is difficult. This is caused by the fact that spacecraft anomaly shows various symptoms and reproducing it is impossible. In this study, we try to find the conditions of when spacecraft failures happen more frequently and give satellite operators useful information. Especially, our study focuses on the geosynchronous satellites which cost is high and required high reliability. We used satellite anomaly data given by Satellite News Digest which is internet newspaper providing space industry news. In our analysis, 88 anomaly cases occurred from 1997 to 2008 shows bad corelation with Kp index. Satellite malfunctions were likely to happen in spring and fall and in local time from midnight to dawn. In addition, we found the probability of anomaly increase when high energy electron flux is high. This is more clearly appeared in solar minimum than maximum period.
Trends of Initial Orbit Determination Accuracy for Time Interval Change Between Three Pairs of Measurement Datas
Hwang, Ok-Jun ; Jo, Jung-Hyun ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 529~546
DOI : 10.5140/JASS.2009.26.4.529
Gauss and Laplace methods for initial orbit determination (IOD) are classical orbit determination tools and have been used very efficiently in optical satellite surveillance system. Several studies related to these two methods have been released until now. In this study, we found that the trends of IOD accuracy for different time interval between three pairs of measurement datas show unexpected results. Therefore, we checked the possible cause of these differences. In order to check various orbit types, we used most of satellite data which is able to obtain. To check the characteristics of methodology-only, we used simulated observation data. And we used real observation data for specific satellites to check the characteristics appeared when we applyed these methods to optical satellite surveillance system. As a result, we found that trends of IOD accuracy for time interval could be different because of satellite position observed.
Observation of Atmospheric Water Vapors Using AIRS
Ha, Ji-Hyun ; Kim, Du-Sik ; Park, Kwan-Dong ; Won, Ji-Hye ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 547~554
DOI : 10.5140/JASS.2009.26.4.547
The Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite, which is one of the Earth Observing System satellites managed by National Aeronautics and Space Administration, provides global measurements of the water vapor in the atmosphere using infrared (IR) channels. In this paper, we restored precipitable water vapor (PWV) over a permanent GPS station in Incheon using the IR measurements of AIRS and compared the result with GPS-based PWV estimates. As a result, AIRS PWV had similar trends with GPS PWV; the bias of AIRS PWV against GPS PWV is 0.3 cm and root mean square error (RMSE) 0.7 cm. In addition, the correlation coefficient between AIRS PWV and GPS PWV was 0.89. Thus we conclude that the AIRS PWV reflects local characteristics of the water vapor content.
Comparison of Precipitable Water Vapor Observations by GPS, Radiosonde and NWP Simulation
Park, Chang-Geun ; Baek, Jeong-Ho ; Cho, Jung-Ho ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 555~566
DOI : 10.5140/JASS.2009.26.4.555
Precipitable water vapor (PWV) derived from a numerical weather prediction (NWP) model were compared to observations derived from ground-based Global Positioning System (GPS) receivers. The model data compared were from the Weather Research and Forecasting (WRF) model short-range forecasts on nested grids. The numerical experimets were performed by selecting the cloud microphysics schemes and for the comparisons, the Changma period of 2008 was selected. The observational data were derived from GPS measurements at 9-sites in South Korea over a 1-month period, in the middle of June-July 2008. In general, the WRF model demonstrated considerable skill in reproducing the temporal and spatial evolution of the PWV as depicted by the GPS estimations. The correlation between forecasts and GPS estimates of PWV depreciated slowly with increasing forecast times. Comparing simulations with a resolution of 18 km and 6 km showed no obvious PWV dependence on resolution. Besides, GPS and the model PWV data were found to be in quite good agreement with data derived from radiosondes. These results indicated that the GPS-derived PWV data, with high temporal and spatial resolution, are very useful for meteorological applications.
Development of Software Correlator for KJJVC
Yeom, J.H. ; Oh, S.J. ; Roh, D.G. ; Kang, Y.W. ; Park, S.Y. ; Lee, C.H. ; Chung, H.S. ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 567~588
DOI : 10.5140/JASS.2009.26.4.567
Korea-Japan Joint VLBI Correlator (KJJVC) is being developed by collaborating KASI (Korea Astronomy and Space Science Institute), Korea, and NAOJ(National Observatory of Japan), Japan. In early 2010, KJJVC will work in normal operation. In this study, we developed the software correlator which is based on VCS (VLBI Correlation Subsystem) hardware specification as the core component of KJJVC. The main specification of software correlator is 8 Gbps, 8192 output channels, and 262,144-points FFT (Fast Fourier Transform) function same as VCS. And the functional algorithm which is same as specification of VCS and arithmetic register are adopted in this software correlator. To verify the performance of developed software correlator, the correlation experiments were carried out using the spectral line and continuum sources which were observed by VERA (VLBI Exploration of Radio Astrometry), NAOJ. And the experimental results were compared to the output of Mitaka FX correlator by referring spectrum shape, phase rate, and fringe detection and so on. Through the experimental results, we confirmed that the correlation results of software correlator are the same as Mitaka FX correlator and verified the effectiveness of it. In future, we expect that the developed software correlator will be the possible software correlator of KVN (Korean VLBI Network) with KJJVC by introducing the correlation post-processing and modifying the user interface as like GUI (Graphic User Interface).
A Study on New Song of the Sky Pacers
Ahn, Sang-Hyeon ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 589~602
DOI : 10.5140/JASS.2009.26.4.589
We investigated 'Song of the Sky Pacers, Adopted to the New Methods'(新法步天歌), the latest version of Joseon's 'Song of the Sky Pacers'(步天歌). Due to the influence of new knowledge on Chinese asterisms imported from the Ching dynasty, 'Song of the Sky Pacers with New Star-Charts' was written in the eighteenth century. However, the disagreement between song and star-charts was causing confusion in practical applications such as Joseon's national examination for selecting astronomers. In order to improve this situation, Royal Observatory of the Joseon dynasty (觀象監) published 'Song of the Sky Pacers, Adopted to the New Methods' based upon star-charts and song in the Sequel of I-Hsiang-K'ao-ch'eng (欽定儀象考成續編). The New Song was edited by a middle-class professional astronomer Yi Jun-yang (李俊養), and corrected by a nobleman Nam Byeong-gil (南秉吉). We establish a brief biography of Yi Jun-yang. The New Song preserves the genuine characteristics of previous Joseon's Song including the format of title of each lunar mansion and description on the location of the Milky Way in the asterisms. The description of the Milky Way was newly written based on the data in volume 31 and 32 of the Sequel of I-Hsiang-K'ao-ch'eng.
A Study on New Pochonka Published in A.D. 1792
Ahn, Sang-Hyeon ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 603~620
DOI : 10.5140/JASS.2009.26.4.603
New Pochonka published in the eighteenth century of the Choson dynasty was composed of star-charts based on the new observations made by Jesuits in China and songs corrected a little bit from previous version of Pochonka. The asterisms in the previous Pochonka are listed in the same order to that in the Song dynasty's literature; while the asterisms in the new Pochonka are listed in accordance with Pu-tien-ko published in China after the Ming dynasty. The Chinese-style twelve-equatorial-section system is adopted in the new Pochonka, while in its song is adopted the zodiac system, which can be seen in the star-charts of previous version of Pochonka. The asterisms belonging to three or four neighboring lunar-mansions are drawn in one chart. Each chart covers asterisms not belonging to a certain range of right ascension, but to a certain lunar mansion. We estimate the forming era of the new Pochonka from the following facts; that the Ling-Tai-I-Hsiang-Chih was used to make charts and footnotes whose archetype can be found in the Chinese literature around A.D. 1700, that these Chinese books were imported into Choson in A.D. 1709, that the naming taboo to the emperor Khang-Hsi was used, that the order of Shen-Hsiu (參宿) was transposed with Tshui-Hsiu (자宿), and that the new Pochonka was substituted for the old version when the rules of Royal Astronomical Bureau was reformed in A.D. 1791. In conclusion, the parent sources of the charts and footnotes of the new Pochonka might be imported from the Ching dynasty around 1709 A.D. to form the new Pochonka between A.D. 1709 and A.D. 1791, and finally to be published in A.D. 1792. We discuss the possible future works to make a firm conclusion.
A Study on the Establishment of Pochonka and Chonmun yucho in the Early Choson Dynasty
Ahn, Sang-Hyeon ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 621~634
DOI : 10.5140/JASS.2009.26.4.621
We investigated the formation of Pochonka (Song of the Sky Pacers) and Chonmun yucho (Selected and classified writings on astrology) of the early Choson dynasty. We recognized that the songs in these books were deeply influenced by those in a Chinese book Tong-zhi published in 1161 A.D., based on the following facts; the contnts of both treatises are described in the same order; the first phrase of the song for Thai-wei-yuan has composed of five words rather than seven words; in particular, Choson's Pochonka has the song that describes the position of the Milky Way relative to asterisms, which was supplemented by the author Zheng Qiao. Since Tong-zhi were brought into Koryo in 1364 A.D., Choson's Pochonka must be formed after that time. In particular, compared with Chinese Pu-tien-ko, Choson's Pochonka stresses the colors of asterisms in order to represent the origin of each asterism with respect to the astronomers, Shih-shen, Kan-te, and Wu-Hsien. We also find that the star-charts in Pochonka and Chonsang-yolcha-punyajido (Chart of the asterisms and the regions they govern) published in the early Choson dynasty are significantly similar in names, number of stars, and shapes of asterisms in them. This fact means that the star-charts in Pochonka originated from either the parent chart of Chonsang-yolcha-punyajido or Chonsang-yolcha-punyajido itself. The parent rubbing was reappeared in 1392 A.D. and carved on stele in 1396 A.D., and so the publication of Pochonka can be dated back to A.D. 1392. Chonmun yucho is a book that was formed by footnoting Pochonka with astrological descriptions in Chinese treatises. The formation period of Chonmun yucho is estimated to be 1440-1450 A.D. from the facts such as the biographical survey of the author Yi Sunji. Furthermore, Pochonka was adopted as a textbook of the government service examination for the astronomy division in Soungwan or the Royal Bureau of Astronomy in 1430 A.D.. We inferred from these facts that Choson's Pochonka was formed between 1392 A.D. and 1430 A.D. as a part of establishment of the cultural and political foundation of the Choson dynasty by adopting the advanced system of the Song dynasty.
Implementation and Test of the Automatic Flight Dynamics Operations for Geostationary Satellite Mission
Park, Sang-Wook ; Lee, Young-Ran ; Lee, Byoung-Sun ; Hwang, Yoo-La ; Galilea, Javier Santiago Noguero ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 635~642
DOI : 10.5140/JASS.2009.26.4.635
This paper describes the Flight Dynamics Automation (FDA) system for COMS Flight Dynamics System (FDS) and its test result in terms of the performance of the automation jobs. FDA controls the flight dynamics functions such as orbit determination, orbit prediction, event prediction, and fuel accounting. The designed FDA is independent from the specific characteristics which are defined by spacecraft manufacturer or specific satellite missions. Therefore, FDA could easily links its autonomous job control functions to any satellite mission control system with some interface modification. By adding autonomous system along with flight dynamics system, it decreases the operator's tedious and repeated jobs but increase the usability and reliability of the system. Therefore, FDA is used to improve the completeness of whole mission control system's quality. The FDA is applied to the real flight dynamics system of a geostationary satellite, COMS and the experimental test is performed. The experimental result shows the stability and reliability of the mission control operations through the automatic job control.
A Study on the Deriving Requirements of ARGO Operation System
Seo, Yoon-Kyung ; Rew, Dong-Young ; Lim, Hyung-Chul ; Park, In-Kwan ; Yim, Hong-Suh ; Jo, Jung-Hyun ; Park, Jong-Uk ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 643~650
DOI : 10.5140/JASS.2009.26.4.643
Korea Astronomy and Space Science Institute (KASI) has been developing one mobile and one stationary SLR system since 2008 named as ARGO-M and ARGO-F, respectively. KASI finished the step of deriving the system requirements of ARGO. The requirements include definitions and scopes of various software and hardware components which are necessary for developing the ARGO-M operation system. And the requirements define function, performance, and interface requirements. The operation system consisting of ARGO-M site, ARGO-F site, and Remote Operation Center (ROC) inside KASI is designed for remote access and the automatic tracking and control system which are the main operation concept of ARGO system. To accomplish remote operation, we are considering remote access to ARGO-F and ARGO-M from ROC. The mobile-phone service allows us to access the ARGO-F remotely and to control the system in an emergency. To implement fully automatic tracking and control function in ARGO-F, we have investigated and described the requirements about the automatic aircraft detection system and the various meteorological sensors. This paper addresses the requirements of ARGO Operation System.
Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems
Keum, Jung-Hoon ; Ra, Sung-Woong ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 651~658
DOI : 10.5140/JASS.2009.26.4.651
Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.
A Analysis for Calibration Site Selection of SAR Satellite
Keum, Jung-Hoon ; Ra, Sung-Woong ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 659~666
DOI : 10.5140/JASS.2009.26.4.659
CALVAL (Calibration & Validation) shall consider payloads characteristics because satellites have one and/or several payloads in order to perform their various missions. SAR satellite, one of various satellite, shall need to use special ground targets, which can reflect the radar signal to the satellite, because it can see objects with reflected radar signal. Therefore, the special ground targets, which are called generally reflector(corner reflector is the one of them) shall be installed and constructed on the ground path. The satellite must access the targets on that path. To accomplish successful calibration, the CALVAL site including corner reflectors will be surveyed and analyzed using various environment characteristics. In this paper, CALVAL site including point targets(corner reflector) for absolute radiometric calibration except one including distributed targets for relative radiometric calibration has been deeply considered.
A Development of Reflector for CAL/VAL of SAR Satellite
Keum, Jung-Hoon ; Ra, Sung-Woong ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 667~676
DOI : 10.5140/JASS.2009.26.4.667
The payload can be classified as a passive and active type. Generally radar satellite to acquire specific information through various radar images will use the SAR (Synthetic Aperture Radar) as active type payload. the principal of SAR satellite is to receive the signal returned from certain objects and/or surfaces in order to construct an radar image. The data acquired from the satellite in its real orbit shall be needed to perform successful CAL/VAL (Calibration & Validation) because the SAR satellite have to receive the returned signal for SAR image construction. In order to do the above, the returned signal shall be related to ground targets. Especially ground target is the corner reflector (CR) for CAL/VAL. Generally the reflector has various types and shapes. Their selection can be dependent on characteristics and mission objectives of SAR satellite. In this paper, reflector focused on the optimal case and effective case has been studied and then the trihedral corner reflector under this study has been designed and its performance also analyzed.
Conceptual Design of Rover's Mobility System for Ground-Based Model
Kim, Youn-Kyu ; Kim, Hae-Dong ; Lee, Joo-Hee ; Sim, Eun-Sup ; Jeon, Sang-Won ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 677~692
DOI : 10.5140/JASS.2009.26.4.677
In recent years, lots of studies on the planetary rover systems have been performed around space advanced agencies such as NASA, ESA, JAXA, etc. Among the various technologies for the planetary rover system, the mobility system, navigation algorithm, and scientific payload have been focused particularly. In this paper, the conceptual design for a ground-based model of planetary rover's mobility system to evaluate mobility and moving stability on ground is presented. The status of overseas research and development of the planetary rover systems is also addressed in terms of technical issues. And then, the requirements of the planetary rover's mobility system are derived by means of considering mobility and stability. The designed rover's mobility system has an active suspension with 6 legs that controls 6 joints on the each leg in order to achieve high stability and mobility. This kind of mobility system has already applied to the ATHELE of NASA for various purposes such as transportation and habitation for human lunar exploration activities in the near future (i.e., Constellation program). However, the proposed system has been designed by focusing on the small-sized unmanned explorations, which may be applied for the future Korea Lunar exploration missions. Therefore, we expect that this study will be an useful reference and experience in order to develop the planetary exploration rover system in Korea.
Computational Analysis of an LOx Supply Line System of an Liquid Rocket Engine
Moon, In-Sang ; Moon, Il-Yoon ; Lee, Soo-Yong ;
Journal of Astronomy and Space Sciences, volume 26, issue 4, 2009, Pages 693~702
DOI : 10.5140/JASS.2009.26.4.693
A computational fluid analysis was performed on an LOx line system of a liquid rocket engine. The model was created with 3D CAD and imbedded to the 3D CFD program. Before the full scale analysis on the system was carried out, each components with simplified models was analyzed to save time and cost. As a result, the inlet pressure of the gas generator should be compensated with a certain device unless the inlet pressure of the line system is sufficiently high. The flow pattern of the exit of the system was dependant upon the location of the orifice as well as the size. As a whole the line system analyzed met the requirements, and will be tested and confirmed after being manufactured.