• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.665-669
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• 2015

The Kepler mission has shown that small planets are extremely common. It is likely that nearly every star in the sky hosts at least one rocky planet. We just need to look hard enough-but this requires vast amounts of telescope time. MINERVA (MINiature Exoplanet Radial Velocity Array) is a dedicated exoplanet observatory with the primary goal of discovering rocky, Earth-like planets orbiting in the habitable zone of bright, nearby stars. The MINERVA team is a collaboration among UNSW Australia, Harvard-Smithsonian Center for Astrophysics, Penn State University, University of Montana, and the California Institute of Technology. The four-telescope MINERVA array will be sited at the F.L. Whipple Observatory on Mt Hopkins in Arizona, USA. Full science operations will begin in mid-2015 with all four telescopes and a stabilised spectrograph capable of high-precision Doppler velocity measurements. We will observe ~100 of the nearest, brightest, Sun-like stars every night for at least five years. Detailed simulations of the target list and survey strategy lead us to expect $15{\pm}4$ new low-mass planets.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.645-647
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• 2015

We have initiated a Very Long Baseline Interferometer (VLBI) monitoring project of 36 methanol maser sources at 6.7 GHz using the Japanese VLBI Network (JVN) and East-Asian VLBI Network (EAVN), starting in August 2010. The purpose of this project is to systematically reveal 3-dimensional (3-D) kine-matics of rotating disks around forming high-mass protostars. As an initial result, we present proper mo- tion detections for two methanol maser sources showing an elliptical spatial morphology, G 002.53+00.19 and G 006.79-00.25, which could be the best candidates associated with the disk. The detected proper motions indicate a simple rotation in G 002.53+00.19 and rotation with expansion in G 006.79-00.25, respectively, on the basis of disk model fits with rotating and expanding components. The expanding motions might be caused by the magnetic-centrifugal wind on the disk.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.79.2-79.2
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• 2012

SN 2011fe (also known as PTF 11kly) is a Type-1a supernova that appeared in M101, 2011 August. Being only 6.4 Mpc away, this supernova has been intensively observed by various facilities in the world. We monitored this supernova in UBVRI, grizY, and ZYJHK-bands using SNUO, LOAO, SOAO, CQUEAN/McDonald, UKIRT telescopes, and small telescopes in Korea and Mongolia. The monitoring observation is still ongoing, and the light curve has been accumulated over a year. We present the results of the long-term monitoring observation, together with a light-curve fitting result. We will also discuss our findings in terms of the usefulness of Type-Ia supernovae as a distance indicator.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.207.1-207.1
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• 2012

One of the key aspects of the upcoming Ultra-Fast Observatory (UFFO) Pathfinder for Gamma-Ray Bursts(GRBs) identification will be the UFFO Burst Alert & Trigger Telescope(UBAT), based on a novel space telescope technique. The UBAT consists of coded mask, hopper, and detector module(DM). The UBAT DM consists of YSO crystal arrays, multi-anode photo mulipliers, and readout electronics. We will present the design and construction of the UBAT DM, and the response of the UBAT DM to X-ray sources.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.113.1-113.1
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• 2012

The characteristics of Doppler shifts in a quiet region of the Sun are investigated by comparing between the $H{\alpha}$ line and the Caii infrared line at 854.2 nm. A small area of $16^{\prime\prime}{\times}40^{\prime\prime}$ was observed for about half an hour with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory. The observed area contains a network region and an internetwork region, and identified in the network region are $H{\alpha}$ fibrils, Caii fibrils and bright points. We infer the Doppler velocity from each line profile at a point with the lambdameter method as a function of half wavelength separation ${\Delta}{\lambda}$. It is confirmed that the bisector of the spatially-averaged Caii line profile has an inverse C-shape of with a significant peak redshift of +1.8 km/s. In contrast, the bisector of the spatially-averaged $H{\alpha}$ line profile has a different shape; it is almost vertically straight or, if not, has a C-shape with a small peak blueshift of -0.5 km/s. In both the lines, the bisectors of bright network points are much different from those of other features in that they are significantly redshifted not only at the line centers, but also at the wings. We also find that the spatio-temporal fluctuation of Doppler shift inferred from the Caii line is correlated with those of the $H{\alpha}$ line. The strongest correlation occurs in the internework region, and when the inner wings rather than the line centers are used to determine Doppler shift. In this region, the RMS value of Doppler shift fluctuation is the largest at the line center, and monotonically decreases with ${\Delta}{\lambda}$. We discuss the physical implications of our results on the formation of the $H{\alpha}$ line and Caii 854.2 nm line in the quiet region chromosphere.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.97.2-97.2
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• 2012

The main payload of Science and Technology Satellite 3 (STSAT-3), Multipurpose InfraRed Imaging System (MIRIS) is the first Korean infrared space mission to explore the near-infrared sky with a small astronomical instrument developed by KASI. The 8-cm passively cooled telescope with a wide field of view (3.67 deg. ${\times}$ 3.67 deg.) will be operated in the wavelength range from 0.9 to $2{\mu}m$. It will carry out wide-band imaging and the Paschen-${\alpha}$ emission line survey. After the calibration of MIRIS in our laboratory, MIRIS has been delivered to SaTReC and successfully assembled into the STSAT-3. The main purposes of MIRIS are to perform the observation of Cosmic Infrared Background (CIB) at two wide spectral bands (I and H band) and to survey the Galactic plane at $1.88{\mu}m$ wavelength, the Paschen-${\alpha}$ emission line. CIB observation enables us to reveal the nature of degree-scale CIB fluctuation detected by the IRTS (Infrared Telescope in Space) mission and to measure the absolute CIB level. The MIRIS will continuously monitor the seasonal variation of the zodiacal light towards the both north and south ecliptic poles for the purpose of calibration as well as the effective removal of zodiacal light. The Pashen-${\alpha}$ emission line survey of Galactic plane helps us to understand the origin of Warm Ionized Medium (WIM) and to find the physical properties of interstellar turbulence related to star formation. Here, we also discuss the observation plan with MIRIS.

• Korean Journal of Optics and Photonics
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• v.22 no.6
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• pp.262-268
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• 2011

MIRIS(Multi-purpose Infra-Red Imaging System) is the main payload of the STSAT-3(Korea Science and Technology Satellite. 3), which is being developed by KASI(Korea Astronomy & Space Institute). EOC(Earth Observation Camera), which is one of two infrared cameras in MIRIS, is the camera for observing infrared rays from the Earth in the range of $3{\sim}5{\mu}m$. The optical system of the EOC is a Cassegrain prescription with aspheric primary and secondary mirrors, and its aperture is 100mm. A ring type flexure supports the EOC primary mirror with pre-loading in order to withstand expected load due to the shock and vibration from the launcher. Here we attempt to use the same mechanism by which a retainer supports the lens. Through opto-mechanical analysis it was confirmed that the EOC primary mirror is effectively supported.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.122-129
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• 1997

Thermo-elastic-plastic analyses used in solving plate forming process are often computationally expensive. To obtain an optimal process of line heating typically requires numerous iterations between the simulation and a finite element analysis. This process often becomes prohibitive due to the amount of computer time required for numerical simulation of line heating process. Therefore, a new techniques that could significantly reduce the computer time required to solve a complex analysis problem would be beneficial. In this paper, we considered factors that influence the bending effect by line heating and developed inference engine by using the concept of artificial neural network. To verify the validity of the neural network, we used results obtained from numerical analysis. We trained the neural network with the data made from numerical analysis and experiments varying the structure of neural network, in other words varying the number of hidden layers and the number of neurons in each hidden layers. From that we concluded that if the number of neurons in each hidden layers is large enough neural network having two hidden layers can be trained easily and errors between exact value and results obtained from trained network are not so large. Consequently, if there are enough number of training pairs, artificial neural network can infer similar results. Based on the numerical results, we applied the artificial neural network technique to deal with mechanical behavior of line heating at simulation stage effectively.

• Journal of Gifted/Talented Education
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• v.25 no.5
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• pp.697-709
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• 2015

This paper aims at shaping remote observatory system environment for schools, developing astronomical observation program using that system and applying it to science-gifted elementary students in order to figure out effects on their scientific investigation ability and attitude. in order to figure out effects of astronomical observation program using remote observatory program on scientific investigation ability and attitude of science-gifted elementary students, test was conducted on gifted students class of 5th grade in A Elementary School(15) and those of 5th grade in B Elementary School(20). The summary of this paper's results are as follows. First, in order to compose remote observatory system, an astronomical telescope available for remote control to transfer actual observed images in real-time was manufactured. Second, learning program for using remote observatory system wad developed by selecting contents through analysis of the curriculum. Third, in order to figure out effects of astronomical observation program using remote observatory program on scientific investigation ability and attitude of science-gifted elementary students. As a result, both of basic investigation ability and integrated investigation abilit, sub-elements of scientific investigation ability, showed significant differences and scientific investigation ability combining basic and integrated investigation abilities showed significant differences as well. Effects of astronomical observation program applying remote observatory also showed significant differences and its sub-elements, openness, collaboration, patience and creativeness did not show significant differences while curiosity, critics and volunteering showed significant differences.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.37.2-37.2
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• 2011

Our previous study on tiny pores (R < 2") observed by HINODE/Solar Optical Telescope (SOT) revealed that the plasma in the pores at the photosphere is always moving down and the pores are surrounded by the strong downward motions (highly red-shifted) of neighboring granulations. From this study, we speculated that the flow motions above the pore should be related with the motions at the photosphere, since the pore is strong magnetic field region. Meanwhile, SNU and KASI installed Fast Imaging Solar Spectrograph (FISS) in the Cude room of the 1.6 m New Solar Telescope (NST) at Big Bear Solar Observatory. FISS is a unique system that can do imaging of H-alpha and Ca II 8542 band simultaneously, which is quite suitable for studying of dynamics of chromosphere. To get some clue on the relationship between the photospheric and low-chromospheric motions at the pore region, we took a coordinate observation with NST/FISS and Hinode/SOT for new emerging active region (AR11117) on October 26, 2010. In the observed region, we could find two tiny pores and two small magnetic islands (SMIs), which have similar magnetic flux with the pores but does not look dark. Magnetic flux density and Doppler velocities at the photosphere are estimated by applying the center-of-gravity (COG) method to the HINODE/spectropolarimeter (SP) data. The line-of-sight motions above the photosphere are determined by adopting the bisector method to the wing spectra of Ha and CaII 8542 lines. As results, we found the followings. (1) There are upflow motion on the pores and downflow motion on the SMIs. (2) Towards the CaII 8542 line center, upflow motion decrease and turn to downward motion in pores, while the speed of down flow motion increases in the SMIs. (3) There is oscillating motion above pores and the SMIs, and this motion keep its pattern along the height. (4) As height increase, there is a general tendency of the speed shift to downward on pores and the SMIs. This is more clearly seen on the other regions of stronger magnetic field. In this talk, we will present preliminary understanding of the coupling of pore dynamics between the photosphere and the low-chromosphere.