• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.76.3-77
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• 2021

GMT secondary mirror system consists of 7 segmented adaptive mirrors. Each segment consists of a thin shell mirror, actuators and a reference body. The thin shell has a few millimeters of thickness so that it can be easily bent by push and pull force of actuators to compensate the wavefront disturbance of light due to air turbulence. The one end of actuator is supported by the reference body and the other end is adapted to this thin shell. One of critical role of the reference body is to provide the reference surface for the thin shell actuators. Therefore, the reference body is one of key components to succeed in development of GMT ASM. Recently, Korea Research Institute of Standards and Science (KRISS) and University of Arizona (UA) has signed a contract that they will cooperate to develop the first set of off-axis reference body for GMT ASM. This project started August 2021 and will be finished in Dec. 2022. The reference body has total 675 holes to accommodate actuators and 144 pockets for lightweighting. The rear surface has a curved rib shape with radius of curvature of 4387 mm with offset of 128.32mm. Since this reference body is placed just above the thin shell so that the front surface shape needs to be close to that of thin shell. The front surface has a concave off-axis asphere, of which radius of curvature is 4165.99 mm and off-axis distance is about 1088 mm. The material is Zerodur CTE class 1 (CTE=0.05 ppm/oC) from SCHOTT. All the actuator holes and pockets are machined normal to the front surface. It is a very complex challenging optical elements that involves sophisticated machining process as well as accurate metrology. After finishing the fabrication of reference body in KRISS, it will be shipped to UA for final touches and finally sent to Adoptica in Italy, in early 2023. This paper presets the development plan for the GMT ASM Reference Body and relevant fabrication and metrology plans.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.78.2-78.2
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• 2013

외계행성 연구는 외계생명체 발견과 밀접한 관계가 있으므로 선진국에서는 국가중점연구로 지정하여 연구에 집중하고 있는 기초학문 연구분야다. 기초학문 연구분야이다. 외계행성 연구는 현재까지 발견을 위주로 행해져 왔고, 그 결과 수백 개의 외계행성이 발견되는 성과를 얻을 수 있었다. 최근에는 지구의 크기와 온도에 근접하는 외계행성이 발견이 언론에 소개 되기도 하였다. 외계행성의 분광 연구는 지금까지 그 밝기가 아주 어두운 관계로 Broad band 관측이 주로 행해졌다 (e.g., Swain et al. 2010). 그러나 최근 3-m급 망원경과 중분산 분광기를 사용한 연구에서 구체적인 적외선 분광구조가 드러나게 되었다 (e.g., Waldmann et al. 2012). 따라서 앞으로 GMT의 분광기를 사용하여 상당히 구체적인 분광구조 관측이 가능하리라고 예측 할 수 있게되었다. 이번 발표에서는 GMT분광기들을 사용한 외계행성 적외선 분광 연구를 원활히 수행하기 위한 준비 단계로 태양계 행성에 대한 국내외 적외선 분광 연구 현황을 논의 하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1636-1643
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• 2003

In this study, bolted joint made of Glass-Mat Reinforced Thermoplastics (GMT) specimen was under tensile loading to investigate the relation between joint strength and glass-fiber weight fraction of the flat plate specimen. The effect of molding conditions such as the initial size of a GMT charge and molding temperatures was investigated under plane strain condition. In consideration of the specimen geometry, minimum end distance and width of the specimen to induce the bearing fracture mode of the bolted joint were determined. And finally, the effect of the outer diameter of washer and clamping pressure on joint strength was also investigated. Since joint strength is dependent on the local glass-fiber weight fraction, experimentally measured strength was modified, considering its irregular values of the specimen molded under various processing conditions in order to obtain a reasonable correlation between the two.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.55.1-55.1
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• 2010

The Giant Magellan Telescope (GMT) is a 24.5m diameter optical/infrared telescope. Its seven 8.4m primary mirrors give it a collecting area equivalent to a 21.4m filled aperture. The ten GMT partners are constructing the telescope at the Las Campanas Observatory in Chile with first light planned for the end of 2018. In this paper, we describe the plans for the first-generation focal plane instrumentation for the telescope. The GMTO Corporation has solicited studies for instruments capable of carrying out the broad range of objectives outlined in the GMT Science Case. Six instruments have been selected for 14 month long conceptual design studies. We describe the features of these instruments and give examples of the major science questions that they can address.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.32.3-32.3
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• 2009

한국천문연구원은 2009년부터 거대 마젤란 망원경 (GMT: Giant Magellan Telescope)의 10% 지분 확보를 주요 골자로 하는 대형광학망원경 개발사업을 수행하고 있다. 이 발표에서는 거대망원경 시대를 겨냥한 키사이언스 그룹의 육성, 첨단 광기계기술확보를 위한 부경제작기술 개발, GMT 관측기기 제작 수주를 위한 국제공동개발사업 등 개발사업의 각종 활동에 대한 2009년 사업 내용 및 2010년 계획에 대하여 발표한다.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.67.2-67.2
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• 2013

The GMT project is in its final stage of Design Development Phase in 2013, moving toward the Construction Phase planned to begin on Jan. 1st, 2014. In this contribution, we present the current status and progress of the GMT project including selection of the first generation instruments, development of primary mirror segments, site preparation, and science case revision along with plans for 2013 when the preparation of construction phase will be made.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.68.1-68.1
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• 2013

The K-GMT group launches a new science program designed to promote the observational research capabilities of Korean Astronomical Society. The science program (SP, hereafter) will provide the access to the observational facilities that is required for the completion of science proposals selected based on their scientific merits. The SP will invite the submission of proposals from all members of Korean Astronomical Society annually starting from mid-2013. We will introduce the rationale, action plan, and major timelines for the new K-GMT SP to the Korean astronomical community members.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.58.1-58.1
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• 2016

K-GMT Science Program, operated by Center for Large Telescopes (CfLAT) in Korea Astronomy and Space Science Institute (KASI), aims to promote the scientific researches by providing the access to the observational facilities such as 4-8m class telescopes and specialized instruments. In 2016, we plan to make various instruments with MMT and Gemini Observatory as well as IGRINS with 2.7m HJS Telescope in McDonald Observatory available to Korean Astronomical Community. We will present the current status and future prospect as well as some early results made from the K-GMT Science Program in past years.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.204.1-204.1
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• 2012

We present SCOTS test simulation for on axis segment of the GMT secondary mirror that is ellipsoidal shape surface of 1.064m in diameter, 4.166747m in radius of curvature, -0.7154 in conic constant and $18.023{\mu}m$ P-V in asphericity. SCOTS test comprises a screen(diffusing sinusoidal fringe source), test surface(GMT secondary mirror), and a camera(CCD detector). We report ray tracing simulation result that is distorted sinusoidal fringe pattern detected at the camera. This simulation is to be used for analysis of experimental design, sensitivity from uncertainty, errors on fabrication and design.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.70.3-70.3
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• 2015

After a short description of the telescope, we will report on the recent developments in three main areas: - Commissioning of the last of LBT's first generation instruments, now well underway, - Adaptive Optics (AO) and ground-layer AO progress and planned upgrades, - Interferometry first science results. We will also explore the future of the facility as it moves to full operation and strive to be the first of the ELTs in the decade-long window in which GMT, TMT, and E-ELT break ground and start taking shape.