• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.217-222
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• 1994

Generally speaking, grouting on the base stabilizes the ground as the aspects of mechanic and engineering properties, with drilling hole at any depth of the earth, and pressuring the cement milk or special chemical grouting material in it. The purpose of grouting on the base is waterproofness and solidification of the ground by earth concreting that the cement milk pass through paticles of soil or crack of rock. This report shows the fundamental properties of microcement compared with those of ordinary portland cement in a point of grouting. It also describes that experimental applications on the treatment of the weathered rock at the constructior of Taegu subway and Boryong earth filled dam site, south of chungchung province, resulted in success.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.98.1-98.1
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• 2012

The Hayabusa mission successfully rendezvoused with its target asteroid 25143 Itokawa in 2005 and brought the asteroidal sample to the Earth in 2009. This mission enabled to connect the S-type asteroids to ordinary chondrites, the counterpart meteorites which exist in near Earth orbit. Recent finding of a fragment from 25143 Itokawa [1] suggested that the asteroid experienced an impact after the injection to the near-Earth orbit. In this presentation, we investigated the evidence of the recent impact on 25143 Itokawa using the onboard camera, AMICA. AMICA took more than 1400 images of Itokawa during the rendezvous phase. It is reported that AMICA images are highly contaminated by lights scattered inside the optics in the longer wavelength. We developed a technique to subtract the scattered light by determining the point spread functions for all available channels. As the result, we first succeeded in the determination of the surface spectra in all available bands. We consider a most fresh-looking compact crater, Kamoi, is a possible impact site.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.267-280
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• 2014

A spacecraft placed in an Earth-Moon L2 quasi-halo orbit can maintain constant communication between the Earth and the far side of the Moon. This quasi-halo orbit could be used to establish a lunar space station and serve as a gateway to explore the solar system. For a mission in an Earth-Moon L2 quasi-halo orbit, a spacecraft would have to be transferred from the Earth to the vicinity of the Earth-Moon L2 point, then inserted into the Earth-Moon L2 quasi-halo orbit. Unlike the near Earth case, this orbit is essentially very unstable due to mutually perturbing gravitational attractions by the Earth, the Moon and the Sun. In this paper, an insertion maneuver of a spacecraft into an Earth-Moon L2 quasi-halo orbit was investigated using the global optimization algorithm, including simulated annealing, genetic algorithm and pattern search method with collision avoidance taken into consideration. The result shows that the spacecraft can maintain its own position in the Earth-Moon L2 quasi-halo orbit and avoid collisions with threatening objects.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.59-62
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• 1998

Satellite communication systems will play an important role in establishing high-speed information communication network ddue to the characteristics of flexibility of bandwidth, mobile communication, wide coverage, multipoint and broadcasting. Also satellite systems have the capability to supply terrestrial B-ISDN with flexible links for accessing networks as well as trunking networks. Therefore, satellites must provide compatibility to earth-based B-ISDN signalling interface, services and network capability. This paper proposed interworking model between terrestrial B-ISDN and satellite B-ISDN signalling protocol and illustrated basic call-process procedure of satellite B-ISDN signalling protocol supporting point-to-point and point-to-multipoint connection.

• Journal of the Korean earth science society
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• v.26 no.8
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• pp.821-827
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• 2005

The Yocheon is an upper stream of Sumjin river, passing through Namwon city. The water temperature of the stream increases from upper stream to downstream. The amount of COD, T-P, T-N, EC, TDS abruptly increases at measuring site 8. Whereas, the pH and DO level abruptly decreases at this site. At this point, the Yocheon river joins another small stream passing through the central part of Namwon city. At a further downstream pass site 8, the amount of COD on April and June (a dry season) is on third grade of water quality for lacustrine. This contamination suggests that sewage from the Namwon city provide COD, T-N, T-P into the stream. At point 2, the high amount of T-N indicates that the upper stream is contaminated by agricultural activity.

• Journal of Power Electronics
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• v.6 no.1
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• pp.18-28
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• 2006

The Electric Power Subsystem (EPS) is one of the most critical systems on any satellite because nearly every subsystem requires power. This makes the choice of power systems the most important task facing satellite designers. The main purpose of the Satellite EPS is to provide continuous, regulated and conditioned power to all the satellite subsystems. It has to withstand radiation, thermal cycling and vacuums in hostile space environments, as well as subsystem degradation over time. The EPS power characteristics are determined by both the parameters of the system itself and by the satellite orbit. After satellite separation from the launch vehicle (LV) to its orbit, in almost all situations, the satellite subsystems (attitude determination and control, communication and onboard computer and data handling (OBC&DH)), take their needed power from a storage battery (SB) and solar arrays (SA) besides the consumed power in the EPS management device. At this point (separation point, detumbling mode), the satellite's angular motion is high and the orientation of the solar arrays, with respect to the Sun, will change in a non-uniform way, so the amount of power generated by the solar arrays will be affected. The objective of this research is to select satellite EPS component types, to estimate solar array illumination parameters and to determine the efficiency of solar arrays during both detumbling and normal operation modes.

• Journal of Korean Elementary Science Education
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• v.34 no.3
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• pp.288-296
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• 2015

This study aimed to analysis of concepts and inquiry activities related to the 'Earth Science' area in the South Korean elementary school textbooks to the current and to seek the improvement of future textbook. For the study, we were collected South Korean elementary school textbooks to the current. After the collection had been made, we were analyzed related to the 'Earth' area in the South Korean elementary school textbooks and were extracted central concepts and inquiry activities. The result of this study: First, there were 'A change in the land', 'Strata and Fossil', 'Volcanoes and Earthquakes', 'Earth and Moon', 'The weather', 'The Solar system and the Star', and 'Seasonal Change' in the central concepts related to the 'Earth' area in the South Korean elementary school textbooks to the current. Second, central concepts were almost the same but the curriculum was changed. Third, inquiry activities also were confirmed to be maintained with little change. This result was believed that it can provide a variety of suggestions at this point in changing the curriculum.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.4
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• pp.454-459
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• 2012

A kernel function of apparent earth resistivity can be estimated using the apparent earth resistivity measured with Wenner's 4 point method. It becomes to solve a nonlinear system to estimate the kernel function of apparent earth resistivity. However it is not simple to get solution of nonlinear system with many unknown variables. This paper suggests the method of estimating kernel function by linearizing this nonlinear system. Finally, various examples of earth structure have been simulated to evaluate the proposed method in this paper.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.433-437
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• 2008

It's essential to build an earth retaining structure at the beginning and end point of a tunnel constructed in a colluvium area. A large scale of colluvial soil may cause a problem to the stability of the excavation ground. An excavation in colluvium has different behavior characteristics from those in a sandy soil due to unstable elements and needs counter measures for it. There are few systematic research efforts on the behavior characteristics of an earth retaining structure installed in colluvial soil. Thus this study set out to collect measuring data from an excavation site at the tunnel pit mouth in colluvium and set quantitative criteria for the safety of an earth retaining structure. After comparing and analyzing the theoretical and empirical earth pressure from the measuring data, the lateral earth pressure distribution acted on the earth retaining wall was suggested.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.1
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• pp.8-13
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• 1997

An electric field due to point dipole within conductor-backed thin dielectric layer above the earth is calculated by using saddle point method When the dielectric layer is thin enough to support a cutoff mdoe, we show that the field may be approximated by sum of contributions of branch points of TE mode and poles of tM mode and that the branch points and poles contributions are interpreted as an evanescent lateral waves and leaky waves, respectively.