• 한국지구과학회지
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• 제43권1호
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• pp.224-235
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• 2022

본 연구는 지난 12년간의 우주위험 관련 언론기사의 토픽모델링 분석을 통해 우주위험별 언론 보도 현황을 알아보기 위한 목적으로 수행되었다. 빅카인즈(BIGKinds)의 뉴스 플랫폼에서 2010년부터 2021년까지의 태양폭풍, 인공우주물체, 자연우주물체에 대한 우주위험 기사를 각각 1200여건 이상 수집하였으며, 키워드 분석, 잠재적 디리클레 할당모형(LDA) 분석을 수행하였다. 그 결과 태양폭풍 관련 기사는 3개의 토픽인 태양폭발이 인공위성에 미치는 영향, 우주전파센터를 중심으로 태양폭발이 우리나라 전파 통신에 미치는 영향, 항공종사자와 우주방사선의 관계로 요약되었다. 인공우주물체 관련 기사의 경우 3개의 토픽으로 인공위성과 우주정거장이 우주쓰레기로부터 위협을 받거나 그 자체가 우주쓰레기가 될 수 있다는 토픽, 영화를 통한 우주쓰레기와 인류의 관계에 대한 토픽, 우주쓰레기 추적·감시 및 처리를 위한 우주강국들의 노력이라는 토픽으로 요약되었다. 자연우주물체 관련 기사는 2개의 토픽으로 국제 우주기관의 근지구소행성에 대한 추적·감시와 충돌 대책과 소행성과 혜성 충돌을 중심으로 공룡과 포유류의 진화 및 멸종 원인으로 요약되었다. 이로부터 2010년부터 현재까지 국내 언론은 우주위험을 사회, 문화 등 다양한 영역에서 총 8개의 주제로 대중들에게 그 위험성과 경각심을 전하는 역할을 하고 있음을 확인하였으며, 이러한 결과를 기반으로 우주위험에 대한 교육방법과 교육정책의 필요성을 제언하였다.

• Journal of Astronomy and Space Sciences
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• 제38권2호
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• pp.119-134
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• 2021

The data set collected during the night of the discovery of a minor body constitutes a too-short arc (TSA), resulting in failure of the differential correction procedure. This makes it necessary to recover the object during subsequent nights to gather more observations that will allow a preliminary orbit to be calculated. In this work, we present a recovery technique based on sampling the admissible region (AdRe) by the constrained Delaunay triangulation. We construct the AdRe in its topocentric and geocentric variants, using logarithmic and exponential metrics, for the following near-Earth-asteroids: (3122) Florence, (3200) Phaethon, 2003 GW, (1864) Daedalus, 2003 BH84 and 1977 QQ5; and the main-belt asteroids: (1738) Oosterhoff, (4690) Strasbourg, (555) Norma, 2006 SO375, 2003 GE55 and (32811) Apisaon. Using our sampling technique, we established the ephemeris region for these objects, using intervals of observation from 25 minutes up to 2 hours, with propagation times from 1 up to 47 days. All these objects were recoverable in a field of vision of 95' × 72', except for (3122) Florence and (3200) Phaethon, since they were observed during their closest approach to the Earth. In the case of 2006 SO375, we performed an additional test with only two observations separated by 2 minutes, achieving a recovery of up to 28 days after its discovery, which demonstrates the potential of our technique.

• 천문학논총
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• 제38권2호
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• pp.25-36
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• 2023

Since interstellar objects like 1I/'Oumuamua and 2I/Borisov originate from exoplanetary systems, even if we do not visit the exoplanetary systems, flyby, rendezvous, and sample return missions of interstellar objects can provide clues to solve the mysteries of cosmic life phenomena such as the origin of exoplanetary systems, galactic evolution, biosignatures (or even technosignatures), and panspermia. In this paper, we review space missions for interstellar object exploration in the stage of mission design or concept study such as Project Lyra, Bridge, Comet Interceptors, and Lightcraft^TM. We also review space missions, OSIRIS-REx and NEA Scout, designed for Near Earth Asteroids(NEA) explorations, to investigate the current state of basic technologies that can be extended to explore interstellar objects in a velocity of ~ 6AU/year. One of the technologies that needs to be developed for interstellar object exploration is a spacecraft propulsion method such as solar sail, which can catch up with the fast speed of interstellar objects. If this kind of propulsion becomes practical for space explorations, interstellar object explorations will mark a new era and serve as a driving force to provide evidences of cosmic life.

• 천문학회보
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• 제38권1호
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• pp.62.2-62.2
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• 2013

It is considered that comets near the ecliptic plane have been injected into inner solar system from Kuiper-belt. Some of them are still active while others are dormant with no detectable tails and comae. These dormant comets have eccentric and/or inclined orbits, which are parameterized by Tisserand parameter TJ<3. In addition, dormant comets can be differentiated from asteroids based on the albedo, because they have low albedo (the geometrical albedos pv<0.1). The conditions of TJ<3 and pv<0.1 have been used as a criteria to discriminate dormant comets from asteroids. However, we must be more careful because there are 'contaminations' from the outer region, i.e. Jovian Trojans (5.05

• Journal of Astronomy and Space Sciences
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• 제22권4호
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• pp.385-392
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• 2005

천구상에서 빠르게 움직이는 인공위성, 우주잔해물 및 빠른 속도의 지구접근천체 등과 같은 고속이동천체들은 별들을 추적하며 관측한 영상에서 선 형태의 궤적으로 나타나게 된다. 이 논문에서는 이러한 궤적을 검출해내기 위해 개발한 궤적탐지 알고리즘에 대한 소개와, 개발된 알고리즘을 이용한 YSTAR-NEOPAT 영상분석결과에 대해 기술하였다. 알고리즘은 기본적으로 외곽선 추적방법을 이용하였으며, 벌들이 밀집한 곳에서의 검출효율을 높이기 위해 차감영상기법을 사용하였다. 알고리즘의 수행속도 테스트 결과, 궤적탐지에 소요되는 시간은 1초 미만으로 대용량 자료의 실시간 분석에도 사용이 가능한 것으로 나타났다. 또한, 검출 결과를 GIF 영상으로 저장함으로써, 눈으로 직접 확인할 수 있도록 하였다. 총 7,000여 장의 YSTAR-NEOPAT 영상을 분석한 결과, 약 700개의 궤적을 발견하였으며 발견된 궤적들 중 고속이동천체는 시계열 영상에서 여러 장에 걸쳐 연속적으로 나타나는 특성을 이용하여 기타 다른 궤적들과 구별해 낼 수 있었다. 이렇게 발견된 고속이동천체는 모두 인공위성 혹은 우주잔해물인 것으로 나타났으며, 기타 궤적들은 우주선 및 유성인 것으로 분류되었다.

• 천문학회보
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• 제39권2호
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• pp.96.1-96.1
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• 2014

The rotation of asteroids can help reveal not only the fundamental characteristics of asteroids but also the origin and evolution of our Solar System. From the photometric observations for NEA 162173 (1999 JU3) and Maria family asteroids using 0.5 m- to 2 m- class telescopes at 10 observatories in the northern hemisphere, I obtained a total of 260 lightcurves for 97 asteroids and derived synodic rotational periods for 51 objects, including newly obtained periods of 34 asteroids. For the sake of efficiency, I developed an observation scheduler, SMART (Scheduler for Measuring Asteroid RoTation) and a photometric analysis software subsystem, ASAP (Asteroid Spin Analysis Package). Based on the lightcurve analysis of NEA 162173 (1999 JU3) and Maria family asteroids, 1) I present the rotational and observational characteristics of 1999 JU3 and provided the Hayabusa-2 Science team with the information on pole orientations, 2) I investigated correlations among rotational periods, amplitudes of lightcurves, and sizes, and conclude that the rotational properties of old-type family asteroids have been changed considerably by the YORP effect. 3) Finally, I found the Yarkovsky footprints on the Maria asteroid family and estimated that approximately 37 to 75 Maria family asteroids larger than 1 km have entered the near-Earth space every 100 Myr. This study should reveal the collisional history and transport route of the members from the resonance region to the near Earth space, for the first time.

• 천문학회지
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• 제41권1호
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• pp.7-15
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• 2008

We carried out a set of simulations to reproduce the performance of wide-field NEO surveys based on the revised population model of Near Earth Objects (NEOs) constructed by Morbidelli (2006). This is the first time where the new model is carefully compared with discovery statistics, and with the exception of population model, the simulation is identical to the procedure described in Moon et al. (2008). Our simulations show rather large discrepancy between the number of NEO discoveries made by the actual and the simulated surveys. First of all, unlike Bottke et al. (2002)'s, Morbidelli (2006)'s population model overestimates the number of NEOs. However, the latter reproduces orbit distributions of the actual population better. Our analysis suggests that both models significantly underestimate Amors, while overestimating the number of Apollos. Our simulation result implies that substantial modifications of both models are needed for more accurate reproduction of survey observations. We also identify Hungaria region (HU) to be one of the most convincing candidates that supply a large fraction of asteroids to the inner Solar System.

• 천문학회보
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• 제40권1호
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• pp.75.2-75.2
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• 2015

Extremely Red Objects (EROs) are characterized by their red optical-infrared colors (e.g., R-Ks > 5.0), which would be caused by either dusty star formation or old stellar population at moderate to high redshifts. We combine deep optical (Subaru R) and near-infrared (CFHT Ks) observations obtained as part of the Subaru $GTO2deg^2$ survey to select EROs over this field and to explore their properties. We present number densities of EROs as a function of magnitudes. We are planning to quantify the environments for EROs and to see if EROs reside in overdense regions.

• 천문학회보
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• 제35권1호
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• pp.87.1-87.1
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• 2010

Main-belt comets (hereafter MBCs) are one of the hottest topics in the solar system astronomy. They are objects orbiting in the main asteroid belt which show cometary activity. Unlike most comets, which spend most of their orbit beyond 5AU from the Sun, MBCs follow near-circular orbits within the asteroid belt that are indistinguishable from the orbits of major population of the asteroids. P/2010 A2, the fifth MBC, was discovered by on January 6, 2010 by Lincoln Near-Earth Asteroid Research. It passed its perihelion at 2.01AU on December 3, 2009, about a month before it was discovered. With an aphelion of only 2.6 AU, P/2010 A2 spends all of its time inside of the frostline ~2.7 AU. We made observations of P/2010 A2 with Nishi-Harima Astronomical Observatory 2-m telescope only a week after the discovery. From the observed images, we found that the dust cloud was composed of large particles (>1mm) impulsively ejected between March and June, 2009. No coma was detected by our observations, suggesting that this object was no longer active. Consequently, we conjecture that these dust particles could be released by the impact collision among asteroids.

• 천문학회보
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• 제37권1호
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• pp.101.2-101.2
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• 2012

An asteroid family is a population of asteroids in the proper orbital element space (a, e, i), considered to have been produced by a disruption of a large parent body presumably through a catastrophic collision. Asteroid families offer unique opportunities to reconstruct and characterize the break-up history of airless bodies in the main-belt. The Maria family is a typical old population (~3${\pm}$1 Gyr) of asteroids that have undergone significant collisional and dynamical evolution in the history of the inner Solar System; it is also believed to be one of the candidate source regions for giant S-type near-earth asteroids (NEAs). However, to date, physical characteristics of this family members such as rotational periods have been known only for 61 of the larger asteroids among 3,230 objects, which accounts for less than 2 percent of the family. In this presentation, we provide some preliminary results of our recent study: out of more than dozen of the family members, lightcurves for eight objects have been obtained for the first time. We plan to increase the number of target objects, and investigate evidences for the Yarkovsky/YORP effect on Maria family based on our observations.