• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.29-29
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• 2014

A fundamental problem in space physics is to explain the origin of energetic charged particles in space close to the Earth and the significant temporal variations of their flux. The particles are primarily electrons and protons although energetic heavy ions such as O+ are sometimes non-negligible. By "energetic" we mean a rather broad energy range of particles from a few tens of keV to well above MeV. Drastic variations of the particle fluxes (by >3 orders of magnitude) occur over both a short time scale like a few minutes and a long time scale like the 11-year sunspot cycle. In this talk I will focus on relativistic energy electrons (~MeV) trapped within the Earth's magnetosphere. They are a primary element of the space weather since they can cause damage to satellites, so often called "killer electrons". Considering that the source particles in both the solar wind and the ionosphere are relatively cold (~eV), the quasi-permanent existence of these very energetic particles close to the Earth has been a surprise to space physicists for decades. Complex electromagnetic processes such as wave-particle interactions within the magnetosphere are believed to play a major role in generating these killer electrons. While detailed physics remains an active research area, for this lecture I will introduce a synthesized picture of how solar activities are related to wave-particle interaction physics inside the magnetosphere. This can be applied to other astrophysical systems.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.35.1-35.1
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• 2008

The importance on the simulation of earth observation optical payloads has been recently emphasized in order to estimate on-orbit imaging performance of the payloads. The estimation should consider all aspects of payload development; design, manufacture, test, assembly, launch and space environment. Until recently several studies have been focused the evaluation of the individual factors rather than the integrated. This paper presents the development of an integrated payload simulator. The simulator analyzes the payload imaging performance based on MTF(Modulation Transfer Function) calculations of the major factors (Diffraction, Aberration, Detector integration, Image motion and etc.) and the simulator can generate realistic artificial earth images as taken by defined earth observation payloads. The simulator is developed for the use of evaluating pre- and post-launch imaging performance and assisting on-board calibration of COMPSAT-3.

• Journal of Astronomy and Space Sciences
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• v.13 no.2
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• pp.181-197
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• 1996

Thc CCD earth image experiment(CEIE) is one of the main payload of the KITSAT-1. Since it was launched on Age. 11, 1992, the CEIE has taken more than 500 images on the earth surface world-wide so far. An image from the space is very different from a feature on the real Earth surface due to various radiometric and geometric distortions. Preprocessing to remove those distortions has to take place before the image data are processed and analyzed further for various applications. This paper summarizes the result of the operation of the CEIE and describes the procedure to perform preprocessing including radiometric and geometric correction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.267-281
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• 2015

The ground movement and changes in earth pressure due to the consecutive construction of retaining wall and underground space were studied experimentally. A soil tank having 160 cm in length and 120 cm in height, was manufactured to simulate the vertical excavation like retaining wall by using 10 separated right side walls and underground space excavation like tunnel by using 5 separated bottom walls. The variation of earth pressure and surface settlement were measured according to the excavation stages. The results showed that the decrease of earth pressure due to the wall movement can cause the increase of earth pressure of the neighboring walls proving the arching effect. Experiments simulating continuous construction sequence also identified arching effect, however only 50% of earth pressure was restored on the 10th right side wall due to the movement of 1st bottom side wall unusually.

• Journal of the Korean Society of Earth Science Education
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• v.15 no.1
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• pp.27-46
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• 2022

The purpose of this study was to examine the perceptions of novelty space among pre-service elementary and secondary earth science teachers. We conducted a survey to explore the perceptions of 38 pre-service elementary school teachers at the National University of Education and 31 pre-service secondary earth science teachers at the Department of Earth Science Education at B University. Semi-structured interviews were conducted with 12 participants, including three pre-service elementary teachers and nine pre-service secondary science teachers. In addition to the elements of novelty space, prior knowledge (cognition), prior outdoor learning experience (psychology), familiarity (geography) with outdoor field learning, and social and technical elements were added. When classified based on elementary and secondary levels, there were statistically significant differences in cognitive, psychological, geographic, and social areas for the elements of novelty space. Statistical differences indicated that the experience or capital related to outdoor learning may have resulted from more pre-service secondary earth science teachers than pre-service elementary teachers. In additional interviews, both elementary and secondary pre-service teachers reported that competencies in the technical domain would be emphasized in the future owing to the necessity and the technical development of virtual-reality-based outdoor field learning programs. This study emphasizes the academic significance of novelty space that should be considered to conduct geological field learning for elementary and secondary earth science pre-service teachers while considering the current post-pandemic educational context.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.142-146
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• 2004

Spaceborne earth observation or astronomical payloads often use Cassegrain-type telescopes due to limits in mass and volume. Precision optical alignment of such a telescope is vital to the success of the mission. This paper describes the alignment simulation and experiment of computer-aided alignment method during the assembly of MAC (Medium-sized Aperture Camera) telescope for spaceborne earth observation.

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.1-11
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• 2015

Earth's magnetopause separating the fast and often turbulent magnetosheath and the relatively stagnant magnetosphere provides various forms of free energy that generate low-frequency surface waves. The source mechanism of this energy includes current-driven kinetic physical processes such as magnetic reconnection on the dayside magnetopause and flux transfer events drifting along the magnetopause, and velocity shear-driven (Kelvin-Helmholtz instability) or density/pressure gradient-driven (Rayleigh-Taylor instability) magnetohydro-dynamics (MHD) instabilities. The solar wind external perturbations (impulsive transient pressure pulses or quasi-periodic dynamic pressure variations) act as seed fluctuations for the magnetopause waves and trigger ULF pulsations inside the magnetosphere via global modes or mode conversion at the magnetopause. The magnetopause waves thus play an important role in the solar wind-magnetosphere coupling, which is the key to space weather. This paper presents recent findings regarding the generation of surface waves (e.g., Kelvin-Helmholtz waves) at the Earth's magnetopause and analytic and observational studies accountable for the linking of the magnetopause waves and inner magnetospheric ULF pulsations, and the impacts of magnetopause waves on the dynamics of the magnetopause and on the inner magnetosphere.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.4
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• pp.149-154
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• 2014

The BeiDou is a satellite-based positioning and navigation system, which is under construction by the China Satellite Navigation Office. Until the June of 2014, the constellation of BeiDou navigation satellite system consists of 14 satellites including five geostationary earth orbit (GEO), five inclined geosynchronous earth orbit (IGSO) and four medium earth orbit (MEO). In this paper, we present the positioning results using BeiDou B1 code measurements obtained from three GNSS reference stations (BHAO, SKMA, MKPO). Combined Beidou/GPS positioning results are also compared to BeiDou and GPS only. BeiDou-only positioning errors for the east-west and north-south direction had less than 2 meter with root mean square (RMS) value. However, the positioning error for the up-down direction had larger than 10 meter at a 95% confidence level. Our results also suggest that the position precision is improved by combined BeiDou/GPS compared to BeiDou-only.

• Journal of Astronomy and Space Sciences
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• v.35 no.1
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• pp.31-37
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• 2018

Pc1 pulsations are geomagnetic fluctuations in the frequency range of 0.2 to 5 Hz. There have been several observations of Pc1 pulsations in low earth orbit by MAGSAT, DE-2, Viking, Freja, CHAMP, and SWARM satellites. However, there has been a clear limitation in resolving the spatial and temporal variations of the pulsation by using a single-point observation by a single satellite. To overcome such limitations of previous observations, a new space mission was recently initiated, using the concept of multi-satellites, named the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE). The SNIPE mission consists of four nanosatellites (~10 kg), which will be launched into a polar orbit at an altitude of 600 km (TBD) in 2020. Four satellites will be deployed in orbit, and the distances between each satellite will be controlled from 10 to 1,000 km by a high-end formation-flying algorithm. One of the possible science targets of the SNIPE mission is observing electromagnetic ion cyclotron (EMIC) waves. In this paper, we report on examples of observations, showing the limitations of previous EMIC observations in low earth orbit, and suggest possibilities to overcome those limitations through a new mission.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.3
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• pp.249-256
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• 1988

The purpose of this paper is to research the estimations of the indoor natural temperature in a case of the earth sheltered space and the 1st basement room in comparison with a conventional housing. The result of this study can be summerized as follows: The natural temperature of the earth sheltered house Summer : $${\theta}es=27.0+1.65sin(2{\pi}/24{\cdot}T-1.34)$$ Winter : $${\theta}ew=11.5+1.15sin(2{\pi}/24{\cdot}T-1.61)$$ The natural temperature of the 1st basement space Summer : $${\theta}us=25.5+1.00sin(2{\pi}/24{\cdot}T-1.72)$$ Winter : $${\theta}uw=13.9+1.10sin(2{\pi}/24{\cdot}T-2.29)$$ From the results of the stated above, we can calculate the cooling and heating load in the earth sheltered house and the underground space exactly and easily at Taejeon City.