• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.91.1-91.1
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• 2010

Despite a surface dominated by carbon-based life, the bulk composition of the Earth is dramatically carbon poor when compared to the material available at formation. Bulk carbon deficiency extends into the asteroid belt representing a fossil record of the conditions under which planets are born. The initial steps of planet formation involve the growth of primitive sub-micron silicate and carbon grains in the Solar Nebula. We present a solution wherein primordial carbon grains are preferentially destroyed by oxygen atoms ignited by heating due to stellar accretion at radii < 5 AU. This solution can account for the bulk carbon deficiency in the Earth and meteorites, the compositional gradient within the asteroid belt, and for growing evidence for similar carbon deficiency in rocks surrounding other stars.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.64-73
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• 2013

In order to observe the deep space more efficiently, a satellite installed with a telescope on earth is needed. Advanced countries in space such as U.S.A and E.U. etc. have obtained and analyzed informations and images of the space from Hubble telescope, Kepler space observatory and Herschel space observatory. This paper studied specifications and operation status of space observation satellite of the several foreign countries and described technologies and plans for the domestic deep space observation satellite.

• Journal of Astronomy and Space Sciences
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• v.19 no.3
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• pp.225-230
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• 2002

Synthetic Aperture Radar (SAR) has been used for mapping the surface geomorphology of cloudy planets like Venus as well as the Earth. The cloud-free Mars is also going to be scanned by SAR in order to detect buried water channels and other features under the very shallow subsurface af the ground. According to the 'Mid and Long-term National Space Development Plan' of Korea, SAR satellites, in addition to the EO (Electro-Optical) satellites, are supposed to be developed in the frame of the KOMPSAT (Korean Multi-Purpose Satellite) program. Feasibility of utilizing a SAR payload on KOMPSAT platform has been studied by KARI in collaboration with Astrium U.K. The purpose of the ShR program is Scientific and Civil applications on the Earth. The study showed that KOMPSAT-2 platform can accommodate a small SAR like Astrium’s MicroSAR. In this paper, system aspects of the satellite design are presented, such as mission scenario, operation concept, and capabilities. The spacecraft design is also discussed and conclusion is followed.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.2
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• pp.166-174
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• 2012

This study is purposed to survey on astronomical observation experiences of elementary students and teachers. Survey samples are 182 elementary students and 51 elementary teachers, and 8 students and 2 teachers among them are interviewed. The results of this study show that most elementary students are not interested in observing constellations, planets, and moon. Also most elementary students and teachers are not taught to observe astronomical objects. Finally, regarding the difficulty of astronomical practice, teachers pointed out that lack of knowledge about astronomy.

• Journal of The Korean Astronomical Society
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• v.34 no.2
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• pp.81-97
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• 2001

Since the first proposal by Paczynski, great efforts to detect Galactic dark matter by detecting light variations of stars located in the Magellanic Clouds and Galactic bulge caused by gravitational microlensing have been and are being carried out and more than 1,000 events have been successfully detected. In this paper, we review the progress in the theoretical and experimental progresses in microlensing. We begin with basics of microlensing and summarize the results obtained from the last 8 year observations along with the implications of the results. We also discuss the usefulness of microlensing in other fields of astronomy such as the stellar atmosphere, Galactic binary systems, and extra-solar planets. We finally discuss the problems of the current experiments and the new types of observations that can overcome these problems.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.69-71
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• 2015

In our previous work, we investigated the orbital dynamics of Asteroid 1934 CT (or 1989 AC or 4179 Toutatis) from epoch 2012-Jul-24 (JDE2456132.5) using the Mercury program package. Asteroid 4179 Toutatis has an Earth and Mars crossing orbit with semimajor axis a = 2.5292 AU and eccentricity e = 0.6294, and therefore the perihelion distance is q = 0.9373 AU and the aphelion distance is Q = 4.1211 AU. After more than 300,000 years, asteroid 4179 Toutatis will escape from the Solar System, but during this time, it will have close-encounters with other planets from Venus to Uranus. As a continuation of this project, we investigated its energy changes in each close encounter. We also determine the energy of this asteroid when it escapes from the Solar System. The result is that during its orbital evolution, the energy of this asteroid changes and gives us negative, zero and positive values.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.102-109
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• 2011

NEOs are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth's neighborhood. When the NEOs with certain size impact in the Earth's surface, it could cause a serious disaster. However, the NEOs that are potentially the most hazardous because they can closely approach the Earth are also the objects that could bemost easily exploited for their raw materials. This paper presents the characteristics of NEOs and the technology trend of advanced countries on spacecraft missions to comets and asteroids.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.291-294
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• 2004

There are many position fixing systems in the world from ancient times. But the principles are to compare the position to want to know with the known position already. The position finding system which is not restricted by weather condition and/or electronic apparatus has been sought. The best system is the GPS as far. But the system has the fatal faults as follows; 1. to depend on satellite's accuracy, 2. not to use underwater. This paper is to investigate theoretically position fixing and north finding by using free gyroscope. This paper introduce a position fixing and north finding method by measuring inclination of 2 free gyroscopes. And this system does not depend on the weather condition and underwater condition. What is more, it could use on the planets, if the gravity exits.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.47.1-47.1
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• 2019

A gas giant formed in a massive protoplanetary disk via gravitational instability migrates inward due to its gravitational interaction with the disk. Planet migration occurs in various ways depending on the disk structure and internal processes, but previous studies only considered quantitative radiative feedback resulting from mass accretion onto the planet. Allowing for accretion feedback, we perform three-dimensional hydrodynamic simulations with GIZMO to investigate orbital evolution of giant planets in a protoplanetary subject to -cooling. This work shows a planet gains mass due to accretion and gradually opens a gap as it moves inward. The migration in the end halts when the planet clears the gas around its orbit. A more massive planet grows its mass faster and migrates more rapidly, stalling at an orbit farther away from the protostar. Models with a cold disk readily construct a circumplanetary disk and result in high mass growth of the planet. Accretion feedback, in general, reduces the rate of the planet growth and delays migration. We discuss our results with GIZMO in comparison with the previous results with different codes.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.33.1-33.1
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• 2019

Protostars grow their mass by the accretion of disk material, which is infalling from the envelope. This accretion process is important to the physical and chemical conditions of the disk and envelope, and thus, the planets yet to be formed from the disk material. Therefore, if we map the physical and chemical properties of disks and envelopes, we can study indirectly the accretion process in star formation. In particular, the chemical distribution in the disk and the inner envelope of a young stellar object is greatly affected by the thermal history, which is mainly determined by the accretion process in the system. In my talk, I will review the episodic accretion model for the low mass star formation and observational efforts to find the evidence of episodic accretion. Finally, I will present our recent ALMA detection of several complex organic molecules associated directly with the planet formation in V883 Ori, which is in the burst accretion phase.