• 천문학회보
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• 제46권2호
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• pp.57.3-57.3
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• 2021

99942 Apophis is an Sq-type Potentially Hazardous Asteroid (PHA) with an estimated diameter of 370 m. It will approach the Earth down to 31,000 km from the surface during the encounter on April 13, 2029 UT, which is closer than geostationary satellites. This once-in-a-20,000 year opportunity would further expand our knowledge on the physical and dynamical processes which are expected to occur due to the gravitational tidal forces when an asteroid encounter with a planet. It will also provide an opportunity to promote great knowledge of the science of planetary defense. The science goal of the Apophis mission is to global-map the asteroid before and after the Earth's approach. In this talk, we will present scientific objectives, and briefly introduce instruments and operation scenarios of the mission.

• Journal of Astronomy and Space Sciences
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• 제33권4호
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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.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.3039-3045
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• 2023

Fiber-reinforced polymer (FRP) composites are considered suitable candidates for structural materials of spacecrafts due to their excellent properties of high strength, light weight, and corrosion resistance. An online health monitoring method for FRP composites must be applied to space structures. However, the application of existing health monitoring methods to space structures is limited due to the harsh space environment. Here, carbon fiber-reinforced polymer (CFRP) composites embedded with fiber Bragg grating (FBG) sensors were prepared to explore the feasibility of strain monitoring using embedded FBG sensors in γ-radiation environment. The analysis of the influence of radiation on the strain monitoring demonstrated that the embedded FBG can be successfully applied to the health monitoring of FRP composites in radiation environment.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1021-1030
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• 2023

We propose an overall procedure for measuring and unfolding fast neutron spectra using a trans-stilbene scintillation detector. Detector characterization was described, including the information on energy calibration, detector resolution, and nonproportionality response. The digital charge comparison method was used for the investigation of neutron-gamma Pulse Shape Discrimination (PSD). A pair of values of 600 ns pulse width and 24 ns delay time was found as the optimized conditions for PSD. A fitting technique was introduced to increase the trans-stilbene Proton Response Function (PRF) by 28% based on comparison of the simulated and experimental electron-equivalent distributions by the Cf-252 source. The detector response matrix was constructed by Monte-Carlo simulation and the spectrum unfolding was implemented using the iterative Bayesian method. The unfolding of simulated and measured spectra of Cf-252 and AmBe neutron sources indicates reliable, stable and no-bias results. The unfolding technique was also validated by the measured cosmic-ray induced neutron flux. Our approach is promising for fast neutron detection and spectroscopy.

• 천문학회보
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• 제32권2호
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• pp.77-77
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• 2007

• 천문학회보
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• 제33권1호
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• pp.61-61
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• 2008

• 천문학회보
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• 제33권2호
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• pp.77.2-77.2
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• 2008

• 천문학회보
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• 제33권2호
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• pp.43.2-43.2
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• 2008

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1997년도 한국우주과학회보 제6권2호
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• pp.33.2-33
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• 1997

No Abstract.See Full-text

• Journal of Astronomy and Space Sciences
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• 제13권2호
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• pp.1-19
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• 1996

Satellite Technology Research Center(SaTReC) of Korean Advanced Institute of Science and Technology(KAIST) has started a collaborative research, development, and training program in the field of space technology. As the result of that, SaTReC has successfully developed and operated the KISTAT-1, which is the first Korean satellite system. From the experience gained. SaTReC has developed the KITSAT-2 with its own technology and man-power and acquired the capability to design and to manufacture small satellite systems. In this paper, an overview of KITSAT-1/2 microsatellite systems and operational results are introduced.