• The Bulletin of The Korean Astronomical Society
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• v.34 no.1
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• pp.120.2-120.2
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• 2009

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.69.2-69.2
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• 2011

We present medium resolution spectra in the near-infrared (IR) band 1.4-1.8 microns at a resolving power of R = 5000-10000 of template stars in G, K, and M types with luminosity classes of III observed by the echelle spectrometer, IRCS, at the SUBARU 8.2 m telescope. Identification of lines in the template star spectra has been completed base on the reference of Arcturus spectrum. We measured equivalent width (EW) of the lines, and analyze the trends of EW through the stellar spectral types.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.39.2-39.2
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• 2010

In this paper, I present the domestic development of near infrared camera systems for the ground telescope and the space satellite. These systems are the first infrared instruments made for astronomical observation in Korea. KASINICS (KASI Near Infrared Camera System) was developed to be installed on the 1.8m telescope of the Bohyunsan Optical Astronomy Observatory (BOAO) in Korea. KASINICS is equipped with a $512{\times}512$ InSb array enable L band observations as well as J, H, and Ks bands. The field-of-view of the array is $3.3'{\times}3.3'$ with a resolution of 0.39"/pixel. It employs an Offner relay optical system providing a cold stop to eliminate thermal background emission from the telescope structures. From the test observation, limiting magnitudes are J=17.6, H=17.5, Ks=16.1 and L(narrow)=10.0 mag at a signal-to-noise ratio of 10 in an integration time of 100 s. MIRIS (Multi-purpose InfraRed Imaging System) is the main payload of the STSAT-3 in Korea. MIRIS Space Observation Camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}{\times}3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI of 30 layers, and GFRP pipe support in the system. Opto-mechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform the Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.13-18
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• 2007

• Publications of The Korean Astronomical Society
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• v.27 no.5
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• pp.391-397
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• 2012

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. It will achieve the high resolution as well as the unprecedented sensitivity from mid to far-infrared range. The FPC (Focal Plane Camera) proposed by KASI as an international collaboration is a near-infrared instrument. The FPC-S and FPC-G are responsible for the scientific observation in the near-infrared and the fine guiding, respectively. The FPC-G will significantly reduce pointing error down to below 0.075 arcsec through the observation of guiding stars in the focal plane. We analyzed the pointing requirement from the focal plane instruments as well as the error factors affecting the pointing stability. We also obtained the expected performance in operation modes. We concluded that the FPC-G can achieve the pointing stability below 0.075 arcsec which is the requirement from the focal plane instruments.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.41.2-41.2
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• 2021

I will start with presenting new results on the stellar populations of galaxies at a redshift of z=9-11, when the universe was only a few hundred million years old. By combining Hubble Space Telescope observations with Spitzer imaging data, I will show how challenging it is currently to measure basic physical properties of these objects such as star-formation rates, stellar masses and stellar ages. In particular, the current measurements greatly depend on the assumptions (priors) for the spectral energy distribution modeling. Finally, I will discuss how the James Webb Space Telescope (JWST) will revolutionize this field next year and allow us to probe and characterize the first generation of galaxies in much greater detail. Specifically, I will present an overview of the JWST Advanced Deep Extragalactic Survey (JADES), a joint program of the JWST/NIRCam and NIRSpec Guaranteed Time Observations (GTO) teams involving 950 hours of observation.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.49.1-49.1
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• 2018

The MATS (Mesosphere Airglow/Aerosol Tomography Spectroscopy) satellite is the next Swedish science microsatellite. We report optical performance test results of the limb telescope, which is the major payload. This telescope is designed with "linear astigmatism-free" (LAF) off-axis optical system in order to have high optical performance across the wide field of view. We measured Modulation Transfer Function (MTF) and Encircled Energy Diameter (EED) of the limb telescope. Full field imaging tests show expected results without linear astigmatism across the full field of view ($5.67^{\circ}{\times}0.91^{\circ}$). Since the amount of stray light is from the earth and the sun, we also simulated and measured the stray light in the field image.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.52.3-53
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• 2016

일반적으로 사용되는 소구경 망원경은 경통에 의한 차폐로 인해 내부 구조를 보기 쉽지 않으므로, 망원경 광학계를 이해하기에는 적합하지 않다. 본 연구에서는 최소한의 배플 만을 사용하여 경통이 없는 구조의 개방형 망원경을 설계 및 제작하였다. 개발된 변환식 반사망원경 키트(TRT Kit, Transformable Reflecting Telescope Kit)는 부경 모듈을 교체하는 방식만으로 뉴턴식 망원경(Newtonian Telescope), 카세그레인식 망원경(Cassegrain Telescope), 그리고 그레고리식 망원경(Gregorian Telescope)으로 변형하는 것이 가능하다. 주경, 부경을 비롯한 망원경의 모든 부분은 사용자가 직접조립할 수 있도록 모듈화(Modularization) 하였다. 또한 부경에 부착된 슬라이딩 장치 및 리니어 스테이지(Linear Stage)는 망원경의 초점을 정밀하게 맞출 수 있도록 설계하였다. TRT Kit를 이용하여 학생들은 세 가지 형태의 망원경 광학계를 직접 조립하고 그 구조 및 성능을 비교해 볼 수 있으며, 광축 정렬, 정밀 초점 조절 과정을 통해 기본적인 광학계의 원리를 이해 할 수 있다.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.39.1-39.1
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• 2010

We are developing a CCD camera named CQUEAN (Camera for Quasars in Early Universe) to search for quasars at z > 7. CQUEAN has a 1024*1024 deep depletion CCD chip and will be attached to 2.1m Otto-Struve Telescope at McDonald Observatory, USA. Although commercial software for the CCD camera is provided by the vendor, we are going to develop our own software to control the other instruments as well, to carry out efficient observation. There are four major parts in our software: Instrument control part controls the camera and filter wheel to obtain imaging data. Quick look window is to display acquired imaging data for quick inspection. Telescope control part interfaces with Telescope Control System (TCS) to move the telescope and to get time or coordinate information. Finally, Observation scripting facility part carries out a series of short exposures in a batch. The whole software will be written in python on linux platform, using the instrument control software libraries provided by the vendors.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.85.2-85.2
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• 2013

We developed autoguiding system for IGRINS (Immersion Grating Infrared Spectrograph) which is a high resolution near-IR spectrograph. This instrument will be attached on the 2.7m telescope at the McDonald observatory in 2013 November. IGRINS consists of three near-Infrared detector modules, i. e., H and K band spectrograph modules and a K band slit camera module, within which we are using the slit camera for autoguiding of the telescope. Comparing to typical optical CCDs, however, the infrared array shows non-uniform responses, higher noises, and many bad pixels. In this poster, we present methods to improve center finding functions and algorithms for the infrared array and the simulator test results of the IGRINS Slit-Camera Package.