• Journal of Astronomy and Space Sciences
• /
• v.18 no.3
• /
• pp.219-230
• /
• 2001

Far-ultraviolet IMaging Spectrograph (FIMS) is under development as the main pay-load of the first Korean science satellite, KAISTSAT-4. An extensive sensitivity and error budget analyses of FIMS optical system have been performed. As an way of estimating aggregate effects of all tolerances, a Monte Carlo simulation is used. The simulation result shows that the optical performance required from the science objectives is achieved within the probability higher than 99.9%.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.2
• /
• pp.40.3-41
• /
• 2015

We performed simultaneous observations of H2O and SiO masers toward VX Sgr using the Korean VLBI Network (KVN) and Source Frequency Phase Referencing (SFPR) method. The observations were carried out at 5 epochs from 2014 February to 2015 June. The relative locations of the SiO with respect to the H2O maser emission were determined at two epochs by SFPR for the first time. The H2O masers show well developed asymmetric outflow features which are spread up to ~300 mas in diameter. On the other hand, the SiO masers show a ring-like structure close to the central star with ~ 30 mas diameter. The SFPR observational results at two epochs (${\varphi}=0.83$ and 0.99) provide similar relative locations of H2O and SiO maser features. These superposed maps of H2O and SiO masers lead us to investigate the development of outflow motions from relatively spherical SiO maser regions close to central star to aspherical H2O maser regions according to optical phase of stellar pulsation together with the prediction of the position of central star.

• Publications of The Korean Astronomical Society
• /
• v.13 no.1 s.14
• /
• pp.39-54
• /
• 1998

We have developed solar observational system in the department of Astronomy & Space Sciences of KyungHee University, in order to monitor solar activities and construct solar database for space weather forecasting at maximum of 23rd solar cycle, as well as an solar education and exercise for undergraduate students. Our solar observational system consists of the full disk monitoring system and the regional observation system for H a fine structure. Full disk monitoring system is made of an energy rejection filter, 16cm refractor, video CCD camera and monitor. Monitored data are recorded to VHS video tape and analog output of video CCD can be captured as digital images by the computer with video graphic card. Another system for regional observation of the sun is made of energy rejection filter, 21cm Schmidt-Cassegrain reflector, H a filter with 1.6A pass band width and $375\times242$ CCD camera. We can observe H a fine structure in active regions of solar disk and solar limb, by using this system. We have carried out intense solar observations for a test of our system. It is found that Quality of our H a image is as good as that of solar images provided by Space Environmental Center. In this paper, we introduce the basic characteristics of the KyungHee Solar Observation System and result of our solar observations. We hope that our data should be used for space weather forecasting with domestic data of RRL(Radio Research Laboratory) and SOFT(SOlar Flare Telescope).

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.236.2-236.2
• /
• 2012

We present the interim results of simultaneous time monitoring observations of SiO v=1, 2, J =1-0, $^{29}SiO$ v=0, J =1-0, and $H_2O$ $6_{16}-5_{23}$ maser lines toward about 60 relatively strong SiO and/or H2O maser sources using the single dishes of the Korean VLBI Network from 2009 September to 2012 June. These monitoring sources are composed of representative semiregular variables, Miras, water fountain sources, preplantary nebulae and SiO maser sources of star forming regions etc. The variations of intensity ratios between SiO and $H_2O$ masers and velocity structures are investigated according to stellar optical phases and observational epochs. Several individual sources which show an interesting feature will be presented here.

• Journal of Astronomy and Space Sciences
• /
• v.18 no.1
• /
• pp.7-14
• /
• 2001

Red giant branch shape and the luminosity of horizontal branch on the (V-I)-V CMD are used to derive the metallicity the globular cluster NGC 5053. The metallicities of NGC 5053 derived by SMR method ([Fe/H]=-2.62$\pm$0.07) and the relation between[Fe/H] and $(V-I)_{0.g}$ ([Fe/H]=-2.50) are in good agreement with previously determined values. This result confirms that the morphologies of RGB and HB on the (V-I)-V CMDs can be good indirect photometric metallicity indicators of galactic globular clusters.

• The Bulletin of The Korean Astronomical Society
• /
• v.24 no.2
• /
• pp.71-71
• /
• 1999

• The Bulletin of The Korean Astronomical Society
• /
• v.29 no.2
• /
• pp.26.2-26.2
• /
• 2004

• The Bulletin of The Korean Astronomical Society
• /
• v.28 no.1
• /
• pp.92-92
• /
• 2003

• The Bulletin of The Korean Astronomical Society
• /
• v.28 no.1
• /
• pp.94-94
• /
• 2003

• The Bulletin of The Korean Astronomical Society
• /
• v.26 no.2
• /
• pp.51-51
• /
• 2001