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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Publications of The Korean Astronomical Society
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Journal DOI :
The Korean Astronomical Society
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Volume & Issues
Volume 22, Issue 4 - Dec 2007
Volume 22, Issue 3 - Sep 2007
Volume 22, Issue 2 - Jun 2007
Volume 22, Issue 1 - Mar 2007
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PHOTOIONIZATION MODELS OF THE WARM IONIZED MEDIUM IN THE GALAXY
Seon, Kwang-Il ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 89~95
DOI : 10.5303/PKAS.2007.22.4.089
The warm ionized medium (WIM) outside classical H II regions is a fundamental gas-phase constituent of the Milky Way and other late-type spiral galaxies, and is traced by faint emission lines at optical wavelengths. We calculate the photoionization models of the WIM in the Galaxy by a stellar UV radiation with the effective temperature 35,000 K assuming not only spherical geometry but also plane parallel geometry, and compare the results with the observed emission line ratios. We also show the dependence of the emission line ratios on various gas-phase abundances. The emergent emission-line ratios are in agreement with the average-values of observed ratios of [S II]
, [N II]
, [O I]
, [O III]
, He I
. However, their extreme values could not be explained with the photoionization models. It is also shown that the addition of all stellar radiation from the OB stars in the Hipparcos stellar catalog resembles that of an O7-O8 type star.
THE LYMAN-CONTINUUM LUMINOSITIES OF OB-TYPE STARS
Seon, Kwang-Il ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 97~101
DOI : 10.5303/PKAS.2007.22.4.097
We are often faced with the task of having to estimate the hydrogen and helium ionizing luminosities of massive stars in the study of H II regions and the warm ionized medium (WIM). Using the results of the most complete compilation of stellar parameters (the effective temperature, stellar radius and surface gravity) and the latest Kurucz stellar atmosphere models, we calculate the ionizing photon luminosities in the
continua from O3 to B5 stars. We compared the theoretical Lyman-continuum luminosity with the observationally inferred luminosity of the H II region around
Vir, and found that the theoretical value is higher than the observed value in contrast to the eariler result.
WEAK GRAVITATIONAL LENSING BY STOCHASTIC GRAVITATIONAL WAVE BACKGROUND
Song, Doo-Jong ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 103~111
DOI : 10.5303/PKAS.2007.22.4.103
On the formulation frameworks of linearly perturbed spacetime and weak gravitational lensing(WGL) we studied the statistical properties of a bundle of light rays propagating through stochastic gravitational wave background(SGWB). For this we considered the SGWB as tensor perturbations of linearly perturbed Friedmann spacetime. Using the solution of null geodesic deviation equation(NGDE) we related the convergence, shear and rotation deformation spectra of WGL with the strain spectra of SGWB. Adopting the astrophysical and cosmological SGWB strain spectra which were already known we investigated the approximated spectral forms of convergence, shear and rotation of WGL.
CATACLYSMIC VARIABLES : SOURCES OF STOCHASTIC GRAVITATIONAL WAVE BACKGROUND
Song, Doo-Jong ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 113~132
DOI : 10.5303/PKAS.2007.22.4.113
On the framework of stochastic gravitational wave background(SGWB) by compact binary systems, we studied the strain spectra of SGWB produced by cosmological cataclysmic variables(CV). For this we reviewed the empirical properties of CVs by using newly published CV catalogue and calculated the cosmological densities of CVs considering the galaxy luminosity function and cosmic stellar birth rate function. Assuming the secular evolution of CVs, we calculated the time scale of CV gravitational wave(GW) radiation and derived formulae for the strain spectra of SGWB by cosmological CVs.
DISK OF Be STAR WITH EMISSION
Ahn, Dae-Gun ; Bae, Jang-Ho ; Lee, Sang-Gak ; Shin, Young-Woo ; Ko, Yeon-Gyung ; Kang, Suk-Chul ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 133~140
DOI : 10.5303/PKAS.2007.22.4.133
We have determined the disk size of Be stars by using
emission. We observed spectra of Be stars with telescope in SNU, equipped with SB SGS (Santa Babara Self Guided Spectrograph) and CCD ST-8. The size of disk of Be stars was estimated with the Be star model of Grundstrom & Gies (2006). This study suggests that the medium resolution spectra taken with small telescope equipped with commercial spectrograph are useful to estimate the approximate size of the
emitting disk around Be stars.
PRELIMINARY RESULTS FOR SHORT-PERIOD VARIABILITY SURVEY (SPVS) : NEW FIELD VARIABLE STARS
Jeon, Young-Beom ; Nam, Ki-Hyung ; Park, Yoon-Ho ; Lee, Kyung-Hoon ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 141~149
DOI : 10.5303/PKAS.2007.22.4.141
Preliminary time-series observations for short-period variability survey (SPVS) were carried out using a 155mm refractor and a
CCD camera at Bohyunsan Optical Astronomy Observatory. We found 21 new variable stars in the
test field region : 9 eclipsing binary stars,
Scuti type stars, a
Doradus type star, and 6 long period variables. The observing field center is R.A.
(J2000.0). The period and amplitude ranges for the short-period variables, i.e.,
Scuti stars, were 0.052day - 0.107day and 0.012mag - 0.064mag, respectively.
ANALYSIS OF KOREAN HISTORICAL COMET RECORDS
Park, So-Yeon ; Chae, Jong-Chul ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 151~168
DOI : 10.5303/PKAS.2007.22.4.151
We have analyzed the comet records in the Korean history books: Samguksagi, Goryeosa, and Joseonwangjosillok. For a comparison, the Chinese and Japanese comet records collected by Kronk (1999) have also been analyzed. Power spectrum of the time series of the comet records is used to find periodic comets. Statistically significant periodicities in the power spectrum are detected at the periods of 38-40 years, about 76 years, and 300-400 years for all Korean, Chinese, and Japanese comet records. We have also calculated the past orbits of some comets that have been recently observed, to check whether or not they were recorded in the history books. We use a multistep method to numerically integrate the comet`s orbital motion backward in time to 51 B.C. The gravitational force due to the Sun and the nine planets, non-gravitational force, and the relativistic effects have been considered. Comparison of comet`s perihelion passage time and the position on the sky with the historical records shows that the comet Halley were recorded at every passage in both Goryeo and Joseon periods. The orbital motion of the comet Pons-Brooks has also been compared with the Korean records. For the comet Tempel-Tuttle, Swift-Tuttle, and Ikeya-Zhang, we have compared our calculation of the orbital motions with those of the previous studies.
CALIBRATION PROCESS OF THE COSMIC INFRARED BACKGROUND EXPERIMENT
Lee, D.H. ; Nam, U.W. ; Kim, G.H. ; Pak, S. ; Zemcov, M. ; Bock, J.J. ; Battle, J. ; Sullivan, I. ; Mason, P. ; Tsumura, K. ; Matsumoto, T. ; Matsuura, S. ; Renbarger, T. ; Keating, B. ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 169~175
DOI : 10.5303/PKAS.2007.22.4.169
The international cooperation project CIBER (Cosmic Infrared Background ExpeRiment) is a rocket-borne instrument, of which the scientific goal is to measure the cosmic near-infrared extra-galactic background to search for signatures of primordial galaxy formation. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. Currently, all the subsystems have been built, and the integration, testing, and calibration of the CIBER system are on process for the scheduled launch in June 2008.
SENSITIVITY CALCULATIONS FOR THE COSMIC IR BACKGROUND OBSERVATIONS BY MIRIS
Lee, Dae-Hui ; Lee, Seong-Ho ; Han, Won-Yong ; Park, Jang-Hyeon ; Nam, Uk-Won ; Jin, Ho ; Yuk, In-Su ; Park, Yeong-Sik ; Park, Seong-Jun ; Lee, Hyeong-Mok ; Park, Su-Jong ; Matsumoto, Toshio ; Cooray, Asantha ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 177~181
DOI : 10.5303/PKAS.2007.22.4.177
We present the sensitivity calculation results for observing the Cosmic Infrared Background (CIRB) by the Multi-purpose IR Imaging System (MIRIS), which will be launched in 2010 as a main payload of the Science and Technology Satellite 3 (STSAT-3). MIRIS will observe in I (
) and H (
) band with a
degree field of view to obtain the large scale structure (
degree) of the CIRB. With the given specifications of the MIRIS, our sensitivity calculation results show that the MIRIS has a detection limit of
(I band) and
(H band), which is appropriate to observe the large scale structure of CIRB.
IMAGE PROCESSING TECHNIC USING MEDIAN FILTERING FOR COMET
Park, Y.S. ; Lee, C.U. ; Jin, H. ; Park, J.H. ; Han, W.Y. ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 183~187
DOI : 10.5303/PKAS.2007.22.4.183
The detection and measurement of faint features in cometary image is generally troublesome due to the high value of the ratio of the brightness of the nucleus to the tail, the large size and low surface brightness of the coma and tail and the disturbing presence of field stars trails. The image processing is based on background removal by median filtering. Sample results are shown for the case study of comet 73P/Schwassmann-Wachmann 3.
PERFORMANCE EVALUATION AND IMPLEMENTATION OF CLOCK SYSTEM FOR KOREAN VLBI NETWORK
Oh, Se-Jin ; Je, Do-Heung ; Lee, Chang-Hoon ; Roh, Duk-Gyoo ; Chung, Hyun-Soo ; Byun, Do-Young ; Kim, Kwang-Dong ; Kim, Hyo-Ryung ; Jung, Gu-Young ; Ahn, Woo-Jin ; Hwang, Jeong-Wook ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 189~199
DOI : 10.5303/PKAS.2007.22.4.189
In this paper, we describe the proposed KVN (Korean VLBI Network) clock system in order to make the observation of the VLBI effectively. In general, the GPS system is widely used for the time information in the single dish observation. In the case of VLBI observation, a very high precise frequency standard is needed to perform the observation in accordance with the observation frequency using the radio telescope with over 100km distance. The objective of the high precise clock system is to insert the time-tagging information to the observed data and to synchronize it with the same clock in overall equipments which used in station. The AHM (Active Hydrogen Maser) and clock system are basically used as a frequency standard equipments at VLBI station. This system is also adopted in KVN. The proposed KVN clock system at each station consists of the AHM, GPS time comparator, standard clock system, time distributor, and frequency standard distributor. The basic experiments were performed to check the AHM system specification and to verify the effectiveness of implemented KVN clock system. In this paper, we briefly introduce the KVN clock system configuration and experimental results.
PRELIMINARY OPTICAL DESIGN OF MIRIS, MAIN PAYLOAD OF STSAT-3
Yuk, I.S. ; Jin, H. ; Lee, S. ; Park, Y.S. ; Lee, D.H. ; Nam, U.W. ; Park, J.H. ; Han, W.Y. ; Lee, J.W. ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 201~209
DOI : 10.5303/PKAS.2007.22.4.201
We have preliminarily designed two infrared optical systems of the multi-purpose infrared camera system (MIRIS) which is the main payload of STSAT-3. Each optical system consists of a Cassegrain telescope, a field lens and a 1:1 re-imaging lens system that is essential for providing a cold stop. The Cassegrain telescope is identical for both of two infrared cameras, but the field correction lens and re-imaging lens system are different from each other because of different bands of wavelength. The effective aperture size is 100mm in diameter and the focal ratio is f/5. The total length of the optical system is 300mm and the position of the cold stop is 25mm from the detector focal plane. The RMS spot size is smaller than
over the whole detector plane.
DESIGN AND STRUCTURAL ANALYSIS OF DOME ENCLOSURE FOR TRACKING ARTIFICIAL SPACE OBJECTS
Seol, K.H. ; Kim, S.J. ; Jang, M. ; Min, S.W. ; Mun, B.S. ; Baek, K.M. ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 211~217
DOI : 10.5303/PKAS.2007.22.4.211
We have been making dual dome enclosures which are useful to track artificial space objects at SSNT (Space Science and Technology Lab.) Kyung Hee University. We verified the safety of the dome enclosures using basic design and structure analyses before manufacturing them, and then performed an optimization analysis for economic and safe systems. The dome enclosure has a fully-open type structure to smoothly operate a telescope made in the style of altazimuth mount with very fast tracking. It is also designed to be safe against extreme weather conditions. The general structure of the observatory system consists of the dual dome enclosures at the top of a container. For the structural analyses, we consider the following two methods: (1) gravitational sustain analysis - how the structure supporting the dome withstand the weight of the dome, and (2) wind load analysis that considers the effect of the wind velocity at the region where the observatory is located. The result of overall deformation is found to be less than 0.551mm and the result of equivalent stress is found to be 20.293Mpa, indicating that the dual dome system is reasonably designed. This means structurally to be safe.
ANALYSIS OF THE SCIENTIFIC INQUIRIES TYPES ON ALMANAC AND HISTORICAL ASTRONOMY IN THE ASTRONOMY AND SPACE SCIENCE Q&A SERVICE
Yim, In-Sung ; Sung, Hyun-Il ; Kim, Kwang-Dong ; Kim, Soon-Wook ; Choe, Seung-Urn ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 219~227
DOI : 10.5303/PKAS.2007.22.4.219
In this paper, we analyze the scientific inquiries type on Almanac and Historical Astronomy asked through the Q&A service in Korea Astronomy and Science Institute(KASI) webpage with the aid of scientific inquiries analysis methods. We also study the contents of the questions. Specifically, we have created statistics of questions and inquiries, and have developed categories to analyze the characteristics of questions with regard to their cognitive aspects. Each question is categorized as either of the two elements based on their recognitive aspect: science knowledge or science study. Each element also has sub-categories that help the reader understand the characteristics of the questions. For the analysis, we used the sample consisting of questions collected from April, 2005 to June, 2007. Through this study, we achieved a better understanding of the questions in the area of Almanac and Historical Astronomy asked in the Q&A service. Throughout this study, we find that the need of questions in the area of Almanac and Historical Astronomy are increasing with time, and the overall quality of the questions is getting improved. As we expect that the number of people using our Q&A service will increase and that the questions will get more difficult to answer, development of improved contents is required.
ANALYSIS OF RESEARCH PROJECTS IN ASTRONOMY AND SPACE SCIENCE IN THE YEAR DURING 2004~05
Kim, Young-Soo ; Kim, Sun-Woo ; Sung, Hyun-Il ; Kim, Byoung-Soo ; Park, Jung-Han ;
Publications of The Korean Astronomical Society, volume 22, issue 4, 2007, Pages 229~236
DOI : 10.5303/PKAS.2007.22.4.229
Many departments in the governmental organization including Ministry of Science & Technology (MOST) allocate some of their budget into research and development in astronomy and space science. We identify the research projects related to astronomy and space science that were funded by the government during fiscal years 2004-2005. Then the distribution of budgets of those projects is analyzed according to several classification schemes and characteristics in order to find out the status and trends of the investment in this field. Five departments had conducted more than 190 projects related to astronomy and space science, which accounted for 7.3% of the government R&D budget in space and aeronautics area. As for most fields of basic science, MOST and Ministry of Education & Human Resources Development invested the most of budget in astronomy related projects. We briefly discuss the implications of this study.