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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
Selecting the target year
Properties of the Variation of the Infrared Emission of OH/IR Stars I. The K Band Light Curves
Suh, Kyung-Won ; Kwon, Young-Joo ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 279~286
DOI : 10.5140/JASS.2009.26.3.279
To study properties of the variation of the infrared emission of OH/IR stars, we collect and analyze the infrared observational data in K band for nine OH/IR stars. We use the observational data obtained for about three decades including recent data from the two micron all sky survey (2MASS) and the deep near infrared survey of the southern sky (DENIS). We use Marquardt-Levenberg algorithm to determine the pulsation period and amplitude for each star and compare them with previous results of infrared and radio investigations.
On Mode Correlation of Solar Acoustic Oscillations
Chang, Heon-Young ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 287~294
DOI : 10.5140/JASS.2009.26.3.287
In helioseismology it is normally assumed that p-mode oscillations are excited in a statistically independent fashion. Unfortunately, however, this issue is not clearly settled down in that two experiments exist, which apparently look in discrepancy. That is, Appourchaux et al. (2000) looked at bin-to-bin correlation and found no evidence that the assumption is invalid. On the other hand, Roth (2001) reported that p-mode pairs with nearby frequencies tend to be anti-correlated, possibly by a mode-coupling effect. This work is motivated by an idea that one may test if there exists an excess of anticorrelated power variations of pairs of solar p-modes. We have analyzed a 72-day MDI spherical-harmonic time series to examine temporal variations of p-mode power and their correlation. The power variation is computed by a running-window method after the previous study by Roth (2001), and then distribution function of power correlation between mode pairs is produced. We have confirmed Roth's result that there is an excess of anti-correlated p-mode pairs with nearby frequencies. On the other hand, the amount of excess was somewhat smaller than the previous study. Moreover, the distribution function does not exhibit significant change when we paired modes with non-nearby frequencies, implying that the excess is not due to mode coupling. We conclude that the origin of this excess of anticorrelations may not be a solar physical process, by pointing out the possibility of statistical bias playing the central role in producing the excess.
Light Curve Analyses of the Eclipsing Binary EROS 1010 in the Large Magellanic Cloud
Hong, Kyeong-Soo ; Kang, Young-Woon ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 295~304
DOI : 10.5140/JASS.2009.26.3.295
We present BV light curves of EROS 1010 which is located in the central bar of the Large Magellanic Cloud. The BV light curves including BR and I light curves observed by the EROS and OGLE projects, have been analyzed using the 2005 version of the Wilson & Devinney Differential Correction program for the photometric solutions. The absolute dimensions of EROS 1010 were calculated by adopting the distance modulus of the Large Magellanic Cloud,
Empirical Forecast of Corotating Interacting Regions and Geomagnetic Storms Based on Coronal Hole Information
Lee, Ji-Hye ; Moon, Yong-Jae ; Choi, Yun-Hee ; Yoo, Kye-Hwa ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 305~316
DOI : 10.5140/JASS.2009.26.3.305
In this study, we suggest an empirical forecast of CIR (Corotating Interaction Regions) and geomagnetic storm based on the information of coronal holes (CH). For this we used CH data obtained from He I
maps at National Solar Observatory-Kitt Peak from January 1996 to November 2003 and the CIR and storm data that Choi et al. (2009) identified. Considering the relationship among coronal holes, CIRs, and geomagnetic storms (Choi et al. 2009), we propose the criteria for geoeffective coronal holes; the center of CH is located between
, and its area in percentage of solar hemispheric area is larger than the following areas: (1) case 1: 0.36%, (2) case 2: 0.66%, (3) case 3: 0.36% for 1996-2000, and 0.66% for 2001-2003. Then we present contingency tables between prediction and observation for three cases and their dependence on solar cycle phase. From the contingency tables, we determined several statistical parameters for forecast evaluation such as PODy (the probability of detection yes), FAR (the false alarm ratio), Bias (the ratio of "yes" predictions to "yes" observations) and CSI (critical success index). Considering the importance of PODy and CSI, we found that the best criterion is case 3; CH-CIR: PODy=0.77, FAR=0.66, Bias=2.28, CSI=0.30. CH-storm: PODy=0.81, FAR=0.84, Bias=5.00, CSI=0.16. It is also found that the parameters after the solar maximum are much better than those before the solar maximum. Our results show that the forecasting of CIR based on coronal hole information is meaningful but the forecast of goemagnetic storm is challenging.
Analysis of Linear and Nonlinear Relative Orbit Dynamics for Satellite Formation Flying
Park, Han-Earl ; Park, Sang-Young ; Lee, Sang-Jin ; Choi, Kyu-Hong ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 317~328
DOI : 10.5140/JASS.2009.26.3.317
Relative dynamic models of satellites which describe the relative motion between two satellites is fundamental for research on the formation flying. The accuracy of various linearized or nonlinear models of relative motion is analyzed and compared. A 'Modeling Error Index (MEI)' is defined for evaluating the accuracy of models. The accuracy of the relative dynamic models in various orbit circumstance are obtained by calculating the modeling error with various eccentricities of the chief orbit and distances between the chief and the deputy. It is found that the modeling errors of the relative dynamic models have different values according to the eccentricity, J2 perturbation, and the distance between satellites. Since the evaluated accuracy of various models in this paper means the error of dynamic models of the formation flying, the results of this paper are very useful for choosing the appropriate relative model of the formation flying mission.
A Study on the Optimal Duration of Daylight Saving Time (DST) in Korea
Mihn, Byeong-Hee ; Ahn, Young-Sook ; Kim, Dong-Bin ; Yang, Hong-Jin ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 329~344
DOI : 10.5140/JASS.2009.26.3.329
Daylight saving time aims at spending effective daylight in summer season. Korea had enforced daylight saving time twelve times from 1948 to 1988. Since 1988, it is not executed, but it is recently discussed the resumption of DST. In this paper, we investigate the trend of DST in other countries, review the history of DST in Korea, and suggest the optimal DST duration in terms of astronomical aspects (times of sunrise and sunset). We find that the starting day of DST in Korea is apt for the second Sunday in Mayor the second Sunday in April according to the time of sunrise or to the difference between Korean standard meridian and observer's, respectively. We also discuss time friction that might be caused by time difference between DST and Korea Standard Time (KST).
Development of a Dual-Circular Polarizer for the KVN Receivers
Chung, Moon-Hee ; Je, Do-Heung ; Han, Seog-Tae ; Lee, Jung-Won ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 345~354
DOI : 10.5140/JASS.2009.26.3.345
A stepped septum polarizer has been designed and fabricated for the 43 GHz band KVN receiver system. The dual-circular polarizer converts left and right hand circularly polarized signals into linear polarizations in two separated rectangular waveguides. Measurements show that the performance of the designed septum polarizer covering 42-48 GHz frequency band is adequate to meet the requirement of KVN receivers. Especially, a polarizer for the KVN receiver of 85-95 GHz frequency band can be fabricated by scaling the dimensions of the septum polarizer developed in this paper.
Automatic Clock and Time Signal System of the Astronomical Agency in East Asia Area
Lee, Yong-Sam ; Kim, Sang-Hyuk ; Jeong, Jang-Hae ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 355~374
DOI : 10.5140/JASS.2009.26.3.355
We analysed the old automatic clock and time signal system that was used by the national astronomical agency in East Asian Area. Jagyeongnu is a kind of water clock that was operated by the flowing water in Joseon Dynasty. Seowoongwan managed the water clock so as to keep the standard time system in the dynasty from the 16th year (1434) of King Sejong's reign. In 1438 the Okru that was invented in the period. Such kind of clock system already was used in China, which was Shui
i hsiang t'ai (水運儀象壹) in 1092. During the period Joseon Dynasty, China and Japan had been kept the time system that one day is divided into 12 shin (12辰) or 100 gak (刻). However detailed part of the system had a little difference among the three countries. Though the whole system of water clock in Joseon had manufactured on the basis of Chinese, it had been gradually developed by own method and idea. In this study we show the historical records of the standard time keeping system in East Asian history. And then we can inform materials on the structure and functional devises for the purpose of new restoration models about the automatic clock and time system.
A Study on the "Bocheonga" of Joseon and China
Kim, Sang-Hyuk ; Yang, Hong-Jin ; Lee, Yong-Bok ; Ahn, Young-Sook ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 375~402
DOI : 10.5140/JASS.2009.26.3.375
Korean historical constellations and their names are similar to Chinese ones. Although Korean historical astronomy is influenced by China, they have distinct differences in each shape and names of the constellations. We, therefore, compare Bocheonga (步天歌) of the early Joseon dynasty (朝鮮,
) preserved in Gyujanggark (奎章閣) with that of the Sui dynasty ((隋代,
of China written by Wang Ximing(王希明) in terms of star charts and descriptions of the contents. We find out that the two books are partly different all over the books. First, there are definite differences in preface, three area of constellations (三垣) in the heaven, and the description of the Milky Way. Second, some of constellations show different in shape, the number of stars. Especially connecting pattern in some constellations shows different in each other. Third, Joseon Bocheonga describes their colors for some stars. These mean that Joseon has a unique tradition of star maps unlike Chinese one. We also summarize the differences and distinctive characteristics of Joseon star charts compared with Chinese ones.
Modelling and Preliminary Prediction of Thermal Balance Test for COMS
Jun, Hyoung-Yoll ; Kim, Jung-Hoon ; Han, Cho-Young ;
Journal of Astronomy and Space Sciences, volume 26, issue 3, 2009, Pages 403~416
DOI : 10.5140/JASS.2009.26.3.403
COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and developed by KARl for communication, ocean and meteorological observations. It will be tested under vacuum and very low temperature conditions in order to verify thermal design of COMS. The test will be performed by using KARI large thermal vacuum chamber, which was developed by KARI, and the COMS will be the first flight satellite tested in this chamber. The purposes of thermal balance test are to correlate analytical model used for design evaluation and predicting temperatures, and to verify and adjust thermal control concept. KARI has plan to use heating plates to simulate space hot condition especially for radiator panels of satellite such as north and south panels. They will be controlled from 90 K to 273 K by circulating GN2 and LN2 alternatively according to the test phases, while the main shroud of the vacuum chamber will be under constant temperature, 90 K, during all thermal balance test. This paper presents thermal modelling including test chamber, heating plates and the satellite without solar array wing and Ka-band reflectors and discusses temperature prediction during thermal balance test.