• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.417-428
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• 2004

We have investigated the optical property of the KAO(Korea Astronomy Observatory) wide field telescope (named NEOPAT-3; Near Earth Object and Satellite Patrol-3) and aligned optical system. The NEOPAT-3 is restricted to V,R,I-filters because of the refractive property of the correcting lens system. Because of the fast focal ratio, the optical performance of the NEOPAT-3 is very sensitive to its alignment factors of the optical system. To make the spot radius smaller than $8{\mu}m$ in rms over 2degree${\times}2$degree field, the optical system must satisfy the following conditions: 1) The tilt error between detector plane and focal plane should be less than 0.05degree. 2) The decenter error between the primary mirror and the correcting lens system should be less than 1mm. 3) The distance error between the primary mirror and the correcting lens system should be less than 2.3mm. In order to align the optical system accurately, we measured the aberrations of the telescope quantitatively by means of curvature sensing technique. NEOPAT-3 is installed temporary on the roof of the TRAO(Taeduk Radio Astronomy Observatory) main building to normalize system performance and to develop automatic observation.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.275-282
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• 2004

We completed the light curves of the contact binary CK Boo for 13 nights from June to July in 2004 using the 1-m reflector and BVR filters at Mt. Lemmon Optical Astronomy Observatory, and determined four new times of minimum light (three timings for primary eclipse, one for secondary). With contact mode of the 1998-version Wilson-Devinney binary model, we analyzed our BVR light curves and Rucinski & Lu (1999)'s radial-velocity ones. As a result, we found CK boo to be A-type over-contact binary ($f=84\%$) with the low mass ratio (q=0.11) and orbital inclination ($i=65^{\circ}$). Absolute dimensions of the system are determined from our new solution; $M_1=1.42Me{\odot},\;M_2=0.15M{\odot},\;R_1=1.47R{\odot},\;R_2=0.59M{\odot}$ and the distance to it is derived as about 129pc. Our distance is well consistent with that ($157{\pm}33pc$) from the Hipparcos trigonometric parallax within the limit of the error yielded by the latter.

• Journal of Astronomy and Space Sciences
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• v.12 no.2
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• pp.204-215
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• 1995

We observed SL-9 impact sites on Jupiter with a CCD and a R filter on the KyungHee University 30-inch telescope between July 17 and September 3, 1994. We identified impact sites of A, C, E, G, H, K, L, Q1, W and G-group, We calculated the moving velocity relative to System II and rotation period of the G, L sites to be from -8.0 to 8.8m/s, and $9^h55^m39.4^s\pm34^s$, respectively. The diameters of G and L sites in our first observation were $1.95\times10^4km,\;and\;2.20\times10^4km$, respectively. In particular, we investigated the evolution of the impact sites by calculating the diffusing rates of the impact clouds.

• Journal of Astronomy and Space Sciences
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• v.19 no.1
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• pp.67-74
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• 2002

Optical observations of Geostationary and Molynia orbit spin-stabilized satellites over the Korean peninsula have been carried out at the Kyung Hee University Observatory with a 30 inch telescope. We have observed 5 spin-stabilized satellites, and obtained 0spin periods, which can be used for deducing a design for each bus model. Verifications of spin periods of 3 known satellites from manufacturer, and observations of 2 unknown satellites were made. The difference between known spin periods and observed spin periods is 0.06sec on the average and the difference of those spin rates is 3.3rpm on the average. Those results indicate that spin periods and spin rates of observed geostationary spin-stabilized satellites are within operating limits. Spin rates of unknown satellites, Fengyun 2B and Molynia 1-87 are 89.3rpm, 78.4rpm earh. It is suggested that the research of spin stabilized satellites can be used for the determinations of standard light sources for short period celestial objects and helpful for the constructions of satellite databases with photometric and/or spectroscopic satellite observations.

• Journal of Astronomy and Space Sciences
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• v.24 no.3
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• pp.249-260
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• 2007

The crustal deformation due to Ocean Tide Loading (OTL) in the Korean peninsula reaches up to ${\sim}3cm$ in the vertical direction. Considering that the achievable positioning accuracy of current state-of-the-art space geodesy technologies is at the several millimeter level, the centimeter-level OTL effect should be precisely modelled and corrected for. This study begins with comparison of ocean tide models and validation of OTL-prediction softwares. Different ocean tide models caused about ${\sim}6mm$ RMS differences in the vertical deformation in the Kyung-gi Bay area. When we analyzed the OTL displacements in the Seoul, Ulsan, and Seogwipo areas where three VLBI observatories are planned to be installed, the maximum displacement of ${\sim}3.5cm$ was predicted in the Seogwipo area and ${\sim}2cm$ in the Seoul and Ulsan areas. When the OTL corrections were not applied in the GPS data processing, the OTL effect propagates into the Zenith Wet Delay (ZWD) estimates, and the scale factor between ZWD differences and OTL displacements was 3.72.

• Journal of Astronomy and Space Sciences
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• v.25 no.1
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• pp.43-52
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• 2008

As the next generation of global satellite navigation system, the Galileo project is about to witness an initial orbit validation stage as the successful test of navigation message transmission from Giove-A in 2007. The Space Geodesy division ana the Radio Astronomy division of the Korea Astronomy & Space Science Institute had collaborated on the field survey for the Galileo Sensor Station (GSS) RF environment of the proposed site near Jeju Tamla University from August 3rd to August 5th, 2006. The power spectrums were measured in full-band $(800{\sim}2000MHz)$ and in-band (E5, E6 and L1 band) in frequency domain for 24 hours respectively. Finally, we performed a time domain analysis to characterize strong in-band interference source based on the result of the previous step.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.670-676
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• 2006

We present a B and V band time-series CCD photometry of ${\delta}$ Scuti type variable star HR 2707. The observation was carried out for 45 nights between November 13, 2001 and February 20, 2002 with a 40 cm telescope equipped with a 1K CCD camera at the Korea National University of Education Optical Astronomy Observatory. Through the time-series CCD photometry we obtained 3011 V band and 6562 B band CCD frames. In some of these data, the V band data obtained for seven nights in January of 2002, had been used as a part of a multi-site campaign by Lopez de Coca et al. (2003). To detect pulsational frequencies, we used Discrete Fourier Transformation (DFT) and linear least square method. We have detected eight resonable pulsational frequencies and compare to previous studies we determine $f_1,\;f_2,\;f_3,\;f_4,\;f_5$ of Lopez do Coca et al. (2003) and $f_4$ for derived from this study are real pulsational frequencies of HR 2707.

• Journal of the Korean earth science society
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• v.25 no.8
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• pp.719-730
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• 2004

The International Astronomy Olympiad (IAO) was established and its foundation were published by the Euro-Asian Astronomical Society (EAAS), in order to spread astronomical knowledge, promote international cooperation in astronomical education area, and recognize the importance of astronomy in far-reaching field of science and human culture. In 1996, the first IAO was held at the Special Astrophysical Observatory (SAO) of the Russian Academy of sciences (RAS) located in the north Caucasus of Russia. Since then, it has been held every year. Here, we will describe the present status of the International Astronomy Olympiad, its major results by year, related institutions, organizations, and the main regulations regarding its operation. In order to measure the levels of scientific knowledge and thinking abilities, we develop a rubric to analyze the characteristics of problems in the IAO with regards to cognitive aspects of scientific inquiry. These problems require high levels of content knowledge and scientific method knowledge. Also high order thinking abilities and high levels of convergent thinking skills, instead of divergent, are needed to solve these problems. Thus, the problems presented are set a high difficulty. Through this analysis, we can understand main purpose of the International Astronomy Olympiad and explore the future direction of the Korea Astronomy Olympiad.

• Journal of the Korean earth science society
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• v.38 no.3
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• pp.209-221
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• 2017

We investigate the star formation rate, stellar mass, and gas-phase metallicity of local starburst galaxies with different star formation time scales based on their optical spectra. The observation is made using the longslit spectrograph attached to the 4K CCD on the Bohyunsan Optical Astronomy Observatory 1.8m telescope, targeting 21 Wolf-Rayet galaxies as young starbursts and 13 UV excess galaxies as slightly older starbursts. A Baldwin-Phillips-Terlevich diagram analysis shows that 50% of the observed targets are pure star-forming galaxies while only 15% are classified as Active Galactic Nuclei. Fraction of galaxies that reside in composite region is higher in UV excess galaxies than in Wolf-Rayet galaxies, suggesting that the AGN development requires extra time after the onset of the star formation. Most of the observed starburst galaxies have stellar masses of $10^{9-11}M_{\odot}$ and stellar formation rates of $0.01-100M_{\odot}yr^{-1}$, and their star formation rates are consistent with that of the SDSS star forming main sequence galaxies of similar stellar mass. There is no significant difference between Wolf-Rayet galaxies and UV excess galaxies in terms of the stellar mass and star formation rate. We also see a mass-metallicity relation for local starbursts with slightly lower metallicity for a given stellar mass, which implies the existence of a strong feedback activity due to the star formation in these galaxies.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.3
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• pp.125-132
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• 2018

KVN(Korean VLBI Network) introduced the Mark6 system of the MIT haystack observatory as a recorder for data recording up to 32 Gbps for VLBI(Very Long Baseline Interferometry) observation. The Mark6 recorder can record data at up to 32Gbps when two systems and 64 HDDs are installed. However, because of the unique recording method that is characteristic of Mark6, we are introducing a large amount of data into a virtual file system, or using a general RAID method, which causes data loss when reading and transferring files at the highest recording speed or file system have. The Flexbuff system, a software recorder developed by JIVE(Joint Institute for VLBI ERIC), can be configured to operate as a data recorder through RAID configuration and network upgrades. In particular, when installed in the Mark6 system, it can record VLBI data at a maximum speed of 32 Gbps with less loss of data compared to the existing Mark6 by utilizing Mark6 resources well. In this paper, we propose that the existing Mark6 system can be operated as Mark6-Flexbuff by installing jive5ab software, and it is verified through experiment that it can be effectively used for VLBI observation operation through data recording test.