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1984년 ~ 2025년까지 1,251 건의 한국우주과학회지를 계간으로 확인하실 수 있습니다.
- The Korean Space Science Society (The Korean Astronomical Society)
- 계간 (Quarterly)
- ISSN : 1225-052x (ISSN : 1225-052x)
1225-052x
- DB구축현황 : 1,251건 (DB Construction : 1,251 Articles)
총 게시글 1,251건
페이지 49/126
481
- Lee, Woo-Ju
- 韓國宇宙科學會誌 = Journal of astronomy & space sciences
- 27, n.1
- pp.11-20
- 2010
- 원문 바로보기
This paper designs a data link between a Lunar Orbiter (LO) and an Earth Station (ES), and analyzes the downlink performance of a space communications system for lunar exploration, conforming to the recommendations by the Consultative Committee for Space Data Systems (CCSDS). The results provided in the paper can be useful references for the design of reliable communication link for the Korean lunar exploration in the near future.
482
- Song, Young-Joo
- Journal of astronomy and space sciences
- 27, n.2
- pp.97-106
- 2010
- 원문 바로보기
To prepare for a Korean lunar orbiter mission, a precise lunar orbit propagator; Yonsei precise lunar orbit propagator (YSPLOP) is developed. In the propagator, accelerations due to the Moon's non-spherical gravity, the point masses of the Earth, Moon, Sun, Mars, Jupiter and also, solar radiation pressures can be included. The developed propagator's performance is validated and propagation errors between YSPOLP and STK/Astrogator are found to have about maximum 4-m, in along-track direction during 30 days (Earth's time) of propagation. Also, it is found that the lifetime of a lunar polar orbiter is strongly affected by the different degrees and orders of the lunar gravity model, by a third body's gravitational attractions (especially the Earth), and by the different orbital inclinations. The reliable lifetime of circular lunar polar orbiter at about 100 km altitude is estimated to have about 160 days (Earth's time). However, to estimate the reasonable lifetime of circular lunar polar orbiter at about 100 km altitude, it is strongly recommended to consider at least <TEX>$50\;{\times}\;50$</TEX> degrees and orders of the lunar gravity field. The results provided in this paper are expected to make further progress in the design fields of Korea's lunar orbiter missions.
483
- Lee, Chang-Moon
- Journal of astronomy and space sciences
- 27, n.2
- pp.117-122
- 2010
- 원문 바로보기
An ionospheric error simulation is needed for creating precise Global Positioning System (GPS) signal using GPS simulator. In this paper we developed Klobuchar coefficients n <TEX>${\alpha}_n$</TEX> and <TEX>${\beta}_n$</TEX> (n = 1, 2, 3, 4) generation algorithms for simulator and verified accuracy of the algorithm. The algorithm extract those Klobuchar coefficients from broadcast (BRDC) messages provided by International GNSS Service during three years from 2006 through 2008 and curve-fit them with sinusoidal and linear functions or constant. The generated coefficients from our developed algorithms are referred to as MODL coefficients, while those coefficients from BRDC messages are named as BRDC coefficients. The maximum correlation coefficient between MODL and BRDC coefficients was found for <TEX>${\alpha}_2$</TEX> and the value was 0.94. On the other hand, the minimum correlation was 0.64 for the case of <TEX>${\alpha}_1$</TEX>. We estimated vertical total electron content using the Klobuchar model with MODL coefficients, and compared the result with those from the BRDC model and global ionosphere maps. As a result, the maximum RMS was 3.92 and 7.90 TECU, respectively.
484
- Jeong, Jang-Hae
- Journal of astronomy and space sciences
- 27, n.2
- pp.81-88
- 2010
- 원문 바로보기
A total of 583 observations (193 in <TEX>${\Delta}b$</TEX>, 190 in <TEX>${\Delta}v$</TEX>, 200 in <TEX>${\Delta}r$</TEX>) for V523 Cas was made on 9 nights from September to December in 2008 using the 100 cm telescope with 2K CCD camera of the Chungbuk National University Observatory. With our data BVR light curves were constructed and 9 times of minimum light were determined. We also obtained physical parameters of the V523 Cas system by analysis of the BVR light curves using the Wilson-Devinney code.
485
- Lee, Sung-Ho
- Journal of astronomy and space sciences
- 27, n.4
- pp.309-318
- 2010
- 원문 바로보기
We introduce a technical approach for reducing three-dimensional infrared (IR) spectroscopic data generated by integral field spectroscopy or slit-scanning observations. The first part of data reduction using IRAF presents a guideline for processing spectral images from long-slit IR spectroscopy. Multichannel image reconstruction, Image Analysis and Display (MIRIAD) is used in the later part to construct and analyze the data cubes which contain spatial and kinematic information of the objects. This technic has been applied to a sample data set of diffuse 2.1218 <TEX>${\mu}m$</TEX> <TEX>$H_2$</TEX> 1-0 S(1) emission features observed by slit-scanning around Sgr A East in the Galactic center. Details of image processing for the high-dispersion infrared data are described to suggest a sequence of contamination cleaning and distortion correction. Practical solutions for handling data cubes are presented for survey observations with various configurations of slit positioning.
486
- Won, Ji-Hye
- 韓國宇宙科學會誌 = Journal of astronomy & space sciences
- 27, n.1
- pp.21-30
- 2010
- 원문 바로보기
In processing space geodetic data, mapping functions are used to convert the tropospheric signal delay along the zenith direction to the line of sight direction. In this study, we compared three mapping functions by evaluating their effects on the tropospheric signal delay and position estimates in GPS data processing. The three mapping functions tested are Niell Mapping Function (NMF), Vienna Mapping Function 1 (VMF1), and Global Mapping Function (GMF). The tropospheric delay and height estimates from VMF1 and GMF are compared with the ones obtained with NMF. The differences among mapping functions show annual signals with the maximum occurring in February or August. To quantitatively estimate the discrepancies among mapping functions, we calculated the maximum difference and the amplitude using a curve fitting technique. Both the maximum difference and amplitude have high correlations with the latitude of the site. Also, the smallest difference was found around <TEX>$30^{\circ}N$</TEX> and the amplitudes increase toward higher latitudes. In the height estimates, the choice of mapping function did not significantly affect the vertical velocity estimate, and the precision of height estimates was improved at most of the sites when VMF1 or GMF was used instead of NMF.
487
- Kim, Chun-Hwey
- Journal of astronomy and space sciences
- 27, n.2
- pp.89-96
- 2010
- 원문 바로보기
BVR CCD observations of GW Cep were made on 15 nights in November through December 2008 with a 1-m reflector at the Jincheon station of the Chungbuk National University Observatory. Nineteen new times of minimum lights for GW Cep were determined and added to a collection of all other times of minima available to us. These data were then intensively analyzed, by reference to an O-C diagram, to deduce the general form of period variation for GW Cep. It was found that the O-C diagram could be interpreted as presenting two different forms of period change: an exclusively quasi-sinusoidal change with a period of 32.6 years and an eccentricity of 0.10; and a quasi-sinusoidal change with a period of 46.2 years and an eccentricity of 0.36 superposed on an upward parabola. Although a final conclusion is somewhat premature at present, the latter seems more plausible because late-type contact binaries allow an inter-exchange of both energy and mass between the component stars. The quasi-sinusoidal characteristics were interpreted in terms of a light-time effect due to an unseen tertiary component. The minimum masses of the tertiary component for both cases were calculated to be nearly the same as the <TEX>$0.23-0.26M\;{\odot}$</TEX>-ranges which is hardly detectable in a light curve synthesis. The upward parabolic O-C diagram corresponding to a secular period increase of about <TEX>$4.12{\times}10^{-8}\;d/yr$</TEX> was interpreted as mass being transferred from the lesser to more massive component. The transfer rate for a conservative case was calculated to be about <TEX>$2.66\;{\times}\;10^{-8}\;M_{\odot}/yr$</TEX> which is compatible with other W UMa-type contact binaries.
488
- Kim, Dong-Hoon
- Journal of astronomy and space sciences
- 27, n.4
- pp.353-357
- 2010
- 원문 바로보기
In general, the information of inertia properties is required to control a spacecraft. The inertia properties are changed by some activities such as consumption of propellant, deployment of solar panel, sloshing, etc. Extensive estimation methods have been investigated to obtain the precise inertia properties. The gyro-based attitude data including noise and bias needs to be compensated for improvement of attitude control accuracy. A modified estimation method based on the law of conservation of angular momentum is suggested to avoid inconvenience like filtering process for noise-effect compensation. The conventional method is modified and beforehand estimated moment of inertia is applied to improve estimation efficiency of product of inertia. The performance of the suggested method has been verified for the case of STSAT-3, Korea Science Technology Satellite.
489
- Lee, Yong-Sam
- Journal of astronomy and space sciences
- 27, n.4
- pp.383-392
- 2010
- 원문 바로보기
Armillary sphere, generally known as, not only astronomical instrument for observing astronomical phenomena but also symbolizes the royal authority and royal political ideology which is based on Confucianism. Among the well-reputed Confucian scholars were built their own armillary spheres. However, these armillary spheres which exist are damaged and most of parts of its have been lost. We analyzed and measured the remnants of armillary spheres which were made by Toegye Lee Hwang, Uam Song Si-Yeol and Goedam Bae Sang-Yeol who were well-reputed Confucian scholars in Joseon Dynasty, and have been executed the restorations of Toegye Lee Hwang and Song Si-Yeols armillary sphere based on the drawings which were drawn as the original form by analysis and measurement of its remnants.
490
- Kang, Young-Woon
- Journal of astronomy and space sciences
- 27, n.2
- pp.75-80
- 2010
- 원문 바로보기
Several survey observations have produced light curves of more than five thousand eclipsing binaries for last 15 years. Future missions such as the Large Synoptic Survey Telescope (LSST), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) and Gaia are expected to yield hundreds thousands of new variable stars and eclipsing binaries. Current methods require a week to analyze the light curves of an eclipsing binary for its physical and orbital parameters. The current methods of analyzing the light curves will be inadequate to treat the overwhelming influx of new data. Therefore we developed a new method to treat large numbers of light curves of eclipsing binaries. We tested the new method by analyzing more than one hundred light curves of the detached and semi-detached eclipsing binaries discovered in the Small Magellan Cloud and present their fitted light curves with observations.