• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.295-304
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• 2016

The atmosphere strongly affects the Earth's spin rotation in wide range of timescale from daily to annual. Its dominant role in the seasonal perturbations of both the pole position and spinning rate of the Earth is once again confirmed by a comparison of two recent data sets; i) the Earth orientation parameter and ii) the global atmospheric state. The atmospheric semi-diurnal tide has been known to be a source of the Earth's spin acceleration, and its magnitude is re-estimated by using an enhanced formulation and an up-dated empirical atmospheric S2 tide model. During the last twenty years, an unusual eastward drift of the Earth's pole has been observed. The change in the Earth's inertia tensor due to glacier mass redistribution is directly assessed, and the recent eastward movement of the pole is ascribed to this change. Furthermore, the associated changes in the length of day and UT1 are estimated.

• Publications of The Korean Astronomical Society
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• v.14 no.2
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• pp.83-89
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• 1999

The Earth is exposed to constant outflow of the solar wind from the outer layers of the Sun, and violent transient events taking place from active regions increase the energy flux of both radiation and particles leaving the Sun. Thus the space surrounding the Earth is a highly dynamic environment that responds sensitively to changes in radiation, particles and magnetic field arriving from the Sun. Nowadays, it becomes increasingly important to understand how the physical system of Earth-space works and how the space around the Earth connects to interplanetary space. In the present paper we describe how explosive solar events, such as CME(Coronal Mass Ejection) and flares affect the Earth-space environment and how the space weather reacts to them. Practical consequences are presented to demonstrate why a broader view of Earth's environment is greatly needed to cope with modern day's inhabitation problem in a rapidly developing space age.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.149-171
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• 2023

ShadowCam is a National Aeronautics and Space Administration Advanced Exploration Systems funded instrument hosted onboard the Korea Aerospace Research Institute (KARI) Korea Pathfinder Lunar Orbiter (KPLO) satellite. By collecting high-resolution images of permanently shadowed regions (PSRs), ShadowCam will provide critical information about the distribution and accessibility of water ice and other volatiles at spatial scales (1.7 m/pixel) required to mitigate risks and maximize the results of future exploration activities. The PSRs never see direct sunlight and are illuminated only by light reflected from nearby topographic highs. Since secondary illumination is very dim, ShadowCam was designed to be over 200 times more sensitive than previous imagers like the Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC). ShadowCam images thus allow for unprecedented views into the shadows, but saturate while imaging sunlit terrain.

• Journal of the Korean Society of Earth Science Education
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• v.6 no.3
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• pp.252-260
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• 2013

The purpose of this study is find out the correlation of level of knowledge of pre-service elementary teacher with space perception ability on 'Earth and Space' of elementary science. During the second semester of 2013, for 15 weeks, the classes were conducted for 3 hours per week and we find out knowledge Understanding degree and select terms offered by 5th grade science courses 'The solar system and the stars', 'Earth and Moon', 'change of seasons' section and measured space perception ability degree of pre-service elementary school teacher with a questionnaire. We analyzed the correlation of understanding level of knowledge in the field of astronomy of pre-service elementary school teacher with space perception ability. The results of the study are presented as follows. First, pre-service elementary school teacher showed a low level of knowledge understanding as it goes the upper grades about upper concept in 'The solar system and the stars', 'Earth and Moon', 'change of seasons' section' of astronomy area of elementary science 'Earth and space sector'. The pre-service elementary school teachers needs to acquire knowledge of astronomy area in elementary school curriculum. Second, pre-service elementary school teacher showed that there are differences individually in 'finding solid body' of sub-element of space perception ability. This shows that 'finding solid body' factor is associated with space perception ability. Third, in the section of 'The earth and the Universe' for elementary education, 'Reflection' and 'Finding solid body' which are low-level components of space perception ability were verified that have a corelationship with general grades in the astronomy conception test.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.624-627
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• 2005

Ministry of Science & Technology (MOST) and Korea Aerospace Research Institute (KARI) are preparing for the first Korean astronaut program based on the mid and long-term basic plan for space development of Korea from the year of 2003. KARI is making plans for the Korean astronaut's missions with Russia. To participate in the International Space Station (ISS) utilization through the Korean astronaut program, KARI investigates a lot of manned space missions. Among the suggested items, Earth observation on the Russian Module of ISS is the one expected mission for a Korean astronaut. This paper is intended to give readers a brief introduction of ISS Russian Module and research fields of Earth observation for astronaut's mission.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.48.1-48.1
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• 2009

In recent years, many candidates for extra-solar planet have been discovered from various measurement techniques. Fueled by such discoveries, new space missions for direct detection of earth-like planets have been proposed and actively studied. TPF instrument is a fair example of such scientific endeavors. One of the many technical problems that space missions such as TPF would need to solve is deconvolution of the collapsed (i.e. spatially and temporally) spectral signal arriving at the detector surface and the deconvolution computation may fall into a local minimum solution, instead of the global minimum solution, in the optimization process, yielding mis-interpretation of the spectral signal from the potential earth-like planets. To this extend, observational and theoretical understanding on the spectral bio-signal from the Earth serves as the key reference datum for the accurate interpretation of the planetary bio-signatures from other star systems. In this study, we present ray tracing computational model for the on-going simulation study on the Earth bio-signatures. A multi-layered atmospheric model and sea ice variation model were added to the existing target Earth model and a hypothetical space instrument (called AmonRa) observed the spectral bio-signals of the model Earth from the L1 halo orbit. The resulting spectrums of the Earth show well known "red-edge" spectrums as well as key molecular absorption lines important to harbor life forms. The model details, computational process and the resulting bio-signatures are presented together with implications to the future study direction.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.34.2-34.2
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• 2010

We built 7 potential extra-terrestrial planets including the full 3D Earth model with various surface types and 6 planet models, each with uniform surface characteristics. The surface types include ice, tundra, forest, grass, ground and ocean. We then imported these 7 planets into integrated ray tracing(IRT) model to compute their disk averaged spectra and to understand the spectral behavior depending on the geometrical view, illumination phase and seasonal change. The IRT computation show that the 6 planets with uniform surfaces exhibit clear spectral differences from that of the Earth. We then built a phase and seasonal DAS database for the 6 uniform surface planets and used them for parametric spectral decomposition technique to derive the Earth DAS. This computation resulted in the first potential solution to the surface type ratio of the Earth compared to the measured earth surface type ratio. The computational details and the implications are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.53.1-53.1
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• 2010

Earth's polar motion has been known for more than one century, and it has been monitored by astrometric observation and recently by space geodetic technique. The Chandler and the annual wobbles are two dominant parts of Earth's polar motion. But according to our recent analysis on a relevant and accurate dataset, another polar motion component, of which period is about 500 days, exists with an amplitude of 20 milliarcseconds in average. This third largest component of polar motion should be caused by resonance of unidentified oscillating mode of Earth, possibly Earth's inner core wobble.

• The Bulletin of The Korean Astronomical Society
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• v.31 no.2
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• pp.35.2-35.2
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• 2006

• Journal of The Korean Astronomical Society
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• v.50 no.2
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• pp.29-39
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• 2017

We investigate two abnormal CME-Storm pairs that occurred on 2014 September 10 - 12 and 2015 March 15 - 17, respectively. The first one was a moderate geomagnetic storm ($Dst_{min}{\sim}-75nT$) driven by the X1.6 high speed flare-associated CME ($1267km\;s^{-1}$) in AR 12158 (N14E02) near solar disk center. The other was a very intense geomagnetic storm ($Dst_{min}{\sim}-223nT$) caused by a CME with moderate speed ($719km\;s^{-1}$) and associated with a filament eruption accompanied by a weak flare (C9.1) in AR 12297 (S17W38). Both CMEs have large direction parameters facing the Earth and southward magnetic field orientation in their solar source region. In this study, we inspect the structure of Interplanetary Flux Ropes (IFRs) at the Earth estimated by using the torus fitting technique assuming self-similar expansion. As results, we find that the moderate storm on 2014 September 12 was caused by small-scale southward magnetic fields in the sheath region ahead of the IFR. The Earth traversed the portion of the IFR where only the northward fields are observed. Meanwhile, in case of the 2015 March 17 storm, our IFR analysis revealed that the Earth passed the very portion where only the southward magnetic fields are observed throughout the passage. The resultant southward magnetic field with long-duration is the main cause of the intense storm. We suggest that 3D magnetic field geometry of an IFR at the IFR-Earth encounter is important and the strength of a geomagnetic storm is strongly affected by the relative location of the Earth with respect to the IFR structure.