• Publications of The Korean Astronomical Society
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• v.25 no.4
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• pp.107-112
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• 2010

By joining the Giant Magellan Telescope (GMT) project, Korean astronomers will get 10% of the GMT time, starting in the late 2010s. To prepare the GMT era, it is important to evaluate the current observational research activities. We surveyed the research programs performed by domestic astronomers during 2007A - 2010A period, using optical/near - IR telescopes with a medium to large aperture mirror (larger than 4 m). We describe the method and criteria of the survey, and present the results of the analysis based on the collected data.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.62.1-62.1
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• 2019

Current large observational projects perform both static and dynamic sky surveys. The Thirty-Minute Target of Opportunity (TMT) is the project focusing on the dynamic sky survey using Korea Microlensing Telescope Network (KMTNet) that is the best observing system to investigate the dynamic sky. TMT aims to perform and experiment on following components : 1) to select transient or variable sources having hour to day scale cadences for future science cases, 2) to optimize the observation strategy for these objects, 3) to provide automated photometric pipelines for the time series data, and 4) to test the data release environment for all astronomers. In the near future, it is expected that a huge number of events will be alerted through large area surveys such as LSST. Therefore, the TMT project will provide opportunities to prepare the future large survey era as well as to understand the nature of interesting astronomical events.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.97-100
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• 2005

The first Space-VLBI project, VSOP, started successfully with the launch of the dedicated space-VLBI satellite HALCA in 1997. The project has been in scientific operation in the 1.6 GHz and 5 GHz bands, and studies have been done mainly of the jet phenomena related to active galactic nuclei. A second generation space- VLBI project, VSOP-2, has been planned by the working group formed at ISAS/JAXA with many collaborators. The spacecraft is planned to observe in the 8, 22 and 43 GHz bands with cooled receivers for the two higher bands, and with a maximum angular resolution at 43 GHz (7 mm) of about 40 micro-arcseconds. The VSOP-2 satellite will also have the capability of the phase-reference and full polarization observations, which will produce more powerful results than those of the VSOP project. Far-future space-VLBI projects following VSOP and VSOP-2, have a large potential to achieve enough resolution and sensitivity to satisfy astronomers in future.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.331-335
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• 2017

We present project updates of the next-generation infrared space mission SPICA (Space Infrared Telescope for Cosmology and Astrophysics) as of November 2015. SPICA is optimized for mid- and far-infrared astronomy with unprecedented sensitivity, which will be achieved with a cryogenically cooled (below 8 K), large (2.5 m) telescope. SPICA is expected to address a number of key questions in various fields of astrophysics, ranging from studies of the star-formation history in the universe to the formation and evolution of planetary systems. The international collaboration framework of SPICA has been revisited. SPICA under the new framework passed the Mission Definition Review by JAXA in 2015. A proposal under the new framework to ESA is being prepared. The target launch year in the new framework is 2027/28.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.393-395
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• 2015

Weak gravitational lensing is an efficient technique for detecting galaxy clusters and probing their mass distribution. We present a weak gravitational lensing analysis of a large sample of galaxy clusters. We have built a nearly complete sample of 50 optically rich clusters, located in the redshift range 0.1 < z < 0.6 and observed in the Canada France Hawaii Telescope Legacy Survey (CFHT-LS). We used weak gravitational lensing to measure, for each galaxy cluster, the density radial profile, the total mass and the mass-to-light ratio (by comparing with the total luminosity of the member galaxies). This project is a preliminary step towards the next analysis of the weak lensing galaxy clusters in the surveys KiDS and VOICE, which are currently collecting data with the VLT Survey Telescope, in Chile.

• Bulletin of the Korean Space Science Society
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• 2008.04a
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• pp.28.3-28.3
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• 2008

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.57.4-58
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• 2020

The B-fields in Star-forming Region Observations (BISTRO) is a large program of the James Clerk Maxwell Telescope (JCMT) to study the roles of magnetic fields in molecular clouds on intermediate scales (a few thousands au or larger scales), in which a large number of researchers over the world are involved. This project was initiated in 2016 with polarimetric observations of nearby star-forming regions and has been extended toward massive and farther regions (BISTRO-2) and various evolutionary stages and environmental conditions (BISTRO-3). The current status of the BISTRO projects is reported. In addition, we discuss magnetic fields in the Serpens Main molecular cloud, which is one of the BISTRO star-forming regions. Utilizing the Histogram of Relative Orientations method, which compares polarization directions with density gradients, we show that magnetic fields are parallel to filaments in less dense filamentary structures but perpendicular to dense ones. Furthermore, the magnetic field directions with respect to density gradients vary again with density in denser core regions, which is understood by core formation and pinched fields. Note: (PI) D. Ward-Thompson, (co-PIs) P. Bastien, T. Hasegawa, W. Kwon, S. Lai, and K. Qiu

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.76.2-76.2
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• 2013

SPICA(SPace Infrared Telescope for Cosmology and Astrophysics) is an infrared space observatory with cooled telescope of 3 m aperture. Because of its large aperture, near- and mid-infrared instruments onboard SPICA require fine guidance with attitude accuracy less than 0.1 arcsecond. The FPC-G is a focal plane camera to achieve this high attitude accuracy and KASI is leading its development. The SPICA project is now under the Risk Mitigation Phase 2 (RMP2) and one of major risks is to satisfy the requirement of pointing and attitude control. To assess the impacts of disturbance sources on the attitude control and devise methods to mitigate possible risks, a software simulator of the FPC-G is under the development. In this presentation, we report the status of development of the simulator and the development plan during the RMP2.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.36.2-36.2
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• 2013

The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. The focal plane instruments onboard SPICA will enable us to resolve many astronomical key issues from the formation and evolution of galaxies to the planetary formation. The FPC-S (Focal Plane Camera - Sciecne) is a near-infrared instrument proposed by Korea as an international collaboration. Owing to the capability of both low-resolution imaging spectroscopy and wide-band imaging with a field of view of $5^{\prime}{\times}5^{\prime}$, it has large throughput as well as high sensitivity for diffuse light compared with JWST. In order to strengthen advantages of the FPC-S, we propose the studies of probing population III stars by the measurement of cosmic near-infrared background radiation and the star formation history at high redshift by the discoveries of active star-forming galaxies. In addition to the major scientific targets, to survey large area opens a new parameter space to investigate the deep Universe. The good survey capability in the parallel imaging mode allows us to study the rare, bright objects such as quasars, bright star-forming galaxies in the early Universe as a way to understand the formation of the first objects in the Universe, and ultra-cool brown dwarfs. Observations in the warm mission will give us a unique chance to detect high-z supernovae, ices in young stellar objects (YSOs) even with low mass, the $3.3{\mu}$ feature of shocked circumstance in supernova remnants. Here, we report the current status of SPICA/FPC project and its extragalactic sciences.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.52.1-52.1
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• 2019

Exploring the vicinity of super-massive black holes (SMBHs) is one of the frontiers in astrophysics. KaVA AGN Science WG has launched its Large Program in 2014 focusing on two SMBHs, Sgr A∗ and M87. They are selected based on their large apparent size. Sgr A∗ is the excellent laboratory for studying gas accretion process onto SMBH and M87 is well known as the best case for investigating plasma outflow ultimately driven by SMBH. For Sgr A∗, KaVA and EAVN provides superb UV-coverage on its emitting region and its scattering medium. In the case of M87, we have conducted high cadence dual-frequency (22and 43GHz )VLBI monitoring to clarify the global profile of the M87 jet velocity field and the spectral index map, which should reflect global structure of magnetic fields in the jet. From 2017, the AGN LP is recognized as multi-wavelength EHT project, conducting quasi-simultaneous coherent observations of M87 and Sgr A∗ with the Event Horizon Telescope (EHT) during its campaign observation periods. AGN WG is reviewing and revising its LP to convert it to EAVN LP. We will briefly report our scientific results and future plan which includes even broader international collaboration, namely East-Asia to Italy Nearly Global (EATING) VLBI to reach higher angular resolution.