• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.415-418
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• 1996

Space Solar Telescope (SST) is a space project for solar research, its main parameters are that total weight 2.0T, sun synchronous polar circular orbit, altitude of the orbit 730KM, 3 axis stabilized attitude system, power 1200W, telemetry of the downlink rate 30Mb/s, size $5{\ast}2{\ast}2\;M^3$, mission life 3 years. It is expected it will be launched in 2001 or later. The main objective is structure and evolution of solar vector magnetic field with very high spatial resolution. The payloads are consisted of 6 instruments: Main optical telescope with 1-M diameter and diffraction limited resolution 0.1 arc second, EUV imaging telescope with a bundle of four telescopes and 0.5 arc second resolution, spectrometric optical coronagraph, wide band spectrometer, H-alpha and white light telescope and solar and interplanetary radiospectrometer. An assessment study between China and Germany is under operation.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.213-214
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• 1996

We are promoting a supernova(SN) search project with medium size (60cm-105cm) telescopes belonging to public observatories in Japan. The main purpose is to measure the SNe Ia rate, which plays an important role in the chemical and dynamical evolution of galaxies. We expect to measure the SN rate in E/SO galaxies within the $35\%$ error after 2 years run, and the longer run will give the smaller error.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.59.3-59.3
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• 2017

We will present the activities of East Asian VLBI Network, EAVN, which consists of around 20 radio telescopes in Japan, Korea, and China with 6,500 km extend. It is a most sensitive and highest VLBI array in the world. We have conducted science verification observations at mainly 8 and 22 GHz. And Japanese VLBI array, VERA, and Korean VLBI array, KVN have combined as KaVA, Korean and VERA Array, and started science observations with open use at 22 and 43 GHz. We will presents some commissioning and science results based on it. Moreover Taiwan is constructing the Greenland telescope to be a millimeter and submillimeter VLBI station, which will be a very powerful station in Global millimeter and submillimeter VLBI array. These activities will be introduced as well.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.65.5-66
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• 2017

In the history of astronomy, observed data were interpreted very frequently based upon data measured at laboratories. For example, all the spectroscopic observations were understood via spectroscopic measurements on nuclei, atoms, and molecules. Recently, computational astrophysics plays a role of bridging experimental data to observations, in particular via numerical modeling of complex astronomical phenomena. This presentation focuses on computational nuclear astrophysics that connects experimental data on nuclei to high-energy observation data obtained by X-ray and gamma-ray telescopes. As an example case, X-ray burst will be discussed. In this phenomenon, observed X-ray light curves and spectra can be modeled by stellar evolution calculations that take nuclear reactions of rare isotopes as input information. This presentation also works as an introduction to the following presentation that will provide more detailed discussion on the experimental aspect of X-ray burst.

• Publications of The Korean Astronomical Society
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• v.2 no.1
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• pp.47-60
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• 1985

Four observational astronomical item, have been pilottested with a 150mm refracting telescope in order to layout the detailed procedures for the suggested (inquiry) activities listed in the high school earth science curriculum and to contrive some adequate instructions for students stressed on how to make proper treatments with the collected materials. The tested items were of sunspots' motion, the size of lunar craters, the Galilian satellites' revolution, and the galactic distribution of stars. Following series of activities are suggested with respect to the way of collecting observational data and of giving proper instruction to students in class: 1) Photography and other material, he made by teacher and/or extracurricular group of students; 2) Replicas (xeroxed, photographs, Or slides) he made from the collected materials, '0 that they are available to all the students in class; 3) Quantative analyses, be taken as student' activity.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.58.1-58.1
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• 2010

We carried out simultaneous 22GHz $H_2O$ and 44GHz $CH_3OH$ maser line surveys of about 1000 galactic YSOs using KVN 21m telescopes. The sources consist of low-mass, intermediate-mass, high-mass YSOs in different evolutionary stages. We will present the preliminary results.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.36.2-36.2
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• 2017

Massive stars (${\geq}8M_{\odot}$) are believed to experience core-collapse and finish their lives as supernova (SN) explosions. Astronomers operating the current SN survey facilities try to catch the first moments of SN explosions. Since neutrinos are emitted first from the SNe before the electromagnetic lights, any neutrino detections from more than two sites within around 10 seconds could be useful alert for early follow-up observations, especially for optical SN follow-up telescopes. In this talk, I will brief the current SN follow-up observation projects, what they want to find out and contribute to SN sciences. Focus will be on the early detection and early sciences on SNe, which is what the Korean Neutrino Telescope can contribute most importantly.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.31.2-31.2
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• 2018

The progenitor star properties of supernovae (SNe) are not fully understood though a large number of SNe have been discovered so far. One of the promising ways to understand the properties of progenitor stars is to study SN early light curve where the shock heated emission after explosion is imprinted in. We have performed Intensive Monitoring Survey of Nearby Galaxies (IMSNG) using a global network of telescopes with the aim to snatch the very early moments of SNe explosion. As one of the fruits of our project, we present the result on the type Ic SN, SN 2017ein which was discovered at 2017 May 25 in NGC 3938. We will present the physical properties of the type Ic SN progenitor star that are obtained from the analysis of early epoch data.

• Journal of the Optical Society of Korea
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• v.9 no.2
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• pp.68-73
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• 2005

When aligning catoptric or catadioptric telescopes for space cameras, it is difficult to align precisely if the field of view is large or there are several reflective surfaces. The quantitative knowledge of mirror misalignments greatly helps align a misaligned telescope precisely, and also reduce the alignment time. This paper describes a generalized reverse-optimization alignment solution algorithm using Zernike sensitivity, and proposes the minimum number of fields to take interferograms. This method was successfully applied on a Cassegrain telescope design for Earth observation from space with arbitrary misalignments and a model including some primary mirror deformation.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.254-257
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• 2004

Both ground and space telescopes are being built larger and larger. Accordingly, the secondary mirrors become larger which are convex mostly on the surface form. Testing convex mirrors becomes more difficult and delicate than testing concave mirrors in optics, because additional optical components are needed to make the reflected rays converge. Hindle type tests are frequently used for measuring the surface deforms of convex mirrors, which employs a meniscus lens to reverse the diverted rays from the mirrors. In case of testing large convex mirrors by using Hindle type tests, attention would be needed as larger meniscus lens is required. A method of modified Hindle test has been studied and the characteristics are analyzed. In this paper, current method of testing convex mirrors is presented, and a new method is discussed.