• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.186-188
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• 2003

Rail Route Alignment in hilly terrain is a difficult task to implement as several natural constraints poses threat to the safety and stability of the alignment. The conventional methods followed to find out the final location survey or the feasibility analysis for alignment is time taking consuming. Some times, due to inaccessibility of the terrain it becomes impossible to carry out such works. The construction works in hilly terrain, which are associated with the proposed alignment, are not same as carried out in plane areas due to a vast contrast between the two areas. Different geological structures such as faults, thrusts, synclines and anticlines are a big problem to carry out normal construction practices. Thus for a safe and stable railway route in the unstable hilly areas, it is required to carry out the feasibility analysis of the proposed alignment to assist the policy makers for a successful implementation of the alignment. In the present work Remote Sensing and GIS has been successfully used to carry out geological feasibility and slope stability analysis for rail route alignment work.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.168-172
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• 2009

Shihmen reservoir was started in May 1963. The main purposes of Shihmen reservoir are for agriculture, power supply, flood control and tourism. Shihme Asn dam is an earth dam. Its crown height is 133m above mean sea level, with length 360 m, watershed 763.4 km², and maximum volume 309 million cms. Turbidity in Shihmen dam was severely affected by typhoons Aere (2004) and Masa (2005). Increased deposition after Aere was 28 million cms. Turbidity at Shihmen Canal Inlet is 3000 NTU (Nephelometry Turbidity Unit). Sediment sluicing strategies for downstream channel are demanded. Therefore, diversionary sediment preventing channel is planned in the upstream of Shihmen reservoir. Finally, turbid flow in tunnel channel is bypassed and diverted its flow down to downstream.

• Journal of the Korean earth science society
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• v.27 no.1
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• pp.20-31
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• 2006

This study analysed student teachers' notable questions about the earth science contents in the elementary science textbooks. The contents of notable questions were defined as ‘notable question contents 1' and 'notable question contents 2'. Both the question contorts are contents about which the number of questions is above three times and from two times to three times as much as the mean number of questions per page of each unit respectively. The results are as follows. First, question contents 1 are found as 'clouds observation', 'geological strata formation' and so on. Question contents 2, 'rainfall measurement', 'moon's movement during one night' and so on are found. Second, the number of interrelationships of main terms in questions increased in each question of question contents 1, but 4 term-patterns are found more in question contents 2 than question contents 1. Third, high interrelationship patterns of terms in question contents 1 are 'coal and petroleum-generation', 'metamorphosis-heat and pressure', 'metamorphosis-heat and pressure-metamorphic rocks', 'planet-sun-comet-revolution' and in question contents 2. 'constellation plate-use', 'dryness and wetness hygrometer-principle', 'seismograph-principle-earthquake', 'earth rotation axis-tilting-occurrence', 'dryness and wetness hygrometer-principle-humidity' and so on. The sources of questions analysed in this study are estimated as the content construction system of textbooks, or students' general questions about the earth science contents. If this is the former, the problems in texts and illustrations in textbooks should be articulated and resolved. And if the latter, the elementary science curriculum has to be reconsidered in view of scientific literacy in earth science.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.17-30
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• 2000

The objective of this study is to evaluate the lateral earth pressure and the stability of small scale retaining wall with waste foundry sand(WFS) mixtures as a controlled low strength materials (CLSM). Three different types of WFS, like Green WFS, Hurane WFS and Coated WFS, were used in this study, and fly ash of Class F type was adopted. To evaluate the lateral earth pressure and the stability of retaining wall, two different samll scale retaining wall tests, which are called an artificially controlled strain method and a natural strain method, were carried out. In case of an artificially controlled strain method, the coefficient of lateral earth pressure, just after backfilling of WF mixtures, was around 0.8 to 1.0, and most of earth pressure was dissipated within 12 hours. In case of a natural strain method, two steps of stage constructions were employed. The mixtures of Hurane WFS and Coated WFS showed fast decrease of earth pressure due to a relatively good drainage. Judging from the sta bility of retaining wall for overturning and sliding, two steps of stage construction for 2 days were enough to finish the backfill of 6-m height of retaining wall. Also, considering the curling effect of WFS mixtures, the stability of retaining wall increased as curling time increased.

• Korean Journal of Remote Sensing
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• v.38 no.6_2
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• pp.1643-1652
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• 2022

Deposited Marine Debris(DMD) can negatively affect marine ecosystems, fishery resources, and maritime safety and is mainly detected by sonar sensors, lifting frames, and divers. Considering the limitation of cost and time, recent efforts are being made by integrating underwater images and artificial intelligence (AI). We conducted a comparative study of You Only Look Once Version 5 (YOLOv5) and You Only Look Once Version 7 (YOLOv7) models to detect DMD from underwater images for more accurate and efficient management of DMD. For the detection of the DMD objects such as glass, metal, fish traps, tires, wood, and plastic, the two models showed a performance of over 0.85 in terms of Mean Average Precision (mAP@0.5). A more objective evaluation and an improvement of the models are expected with the construction of an extensive image database.

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.17-30
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• 2012

A new trenchless tunneling method using pressurizing support has been developed. As it overcomes shortcomings of conventional methods, it is applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies the pressure corresponding to the magnitude of the relaxed earth pressure caused by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through several ways such as numerical tests and various model tests. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long road tunnel that passes under Yeongdong Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months. It decreases the construction period to 35% compared to that of conventional methods, and ground displacement was almost negligible.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.407-413
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• 2006

Artificial aggregates made by coal fly ash that is classified as an industrial by-product was tested to oxidize hydrogen sulfide under various testing conditions. For the determination of optimum condition for converting coal fly ash to aggregates, specimens were prepared by varying ratio of fly ash, cement, water content, and foaming agent. These specimens were tested to determine specific gravity, water absorption, and compressive strength. Specimens, which were used for the removal of hydrogen sulfide, were selected based on the measured specific gravity, water absorption, and compressive strength. Tests for hydrogen sulfide removal were performed via batch and column tests. Under the testing conditions used in this study, removal rates of hydrogen sulfide were linearly proportional to amounts of coal fly ash, and further increased when water was added.

• Korean Journal of Construction Engineering and Management
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• v.5 no.3 s.19
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• pp.71-78
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• 2004

In conventional method of supporting soil shuttering wall during excavation a system of struts and wales to provide cross-lot bracing is common in trench excavations and other excavations of limited width. This method, however, becomes difficult and costly to be adopted for large excavations since heavily braced structural systems are required. Another expensive and unsafe situations are expected when temporary struts must be removed for the construction of underground structures. This paper introduces innovative strut systems which can be used as permanent underground structures after its role as brace system to resist earth pressure during excavation phase. Underground structural system suggested from architect is checked against the soil lated pressures before the analysis of stresses developed from gravity loads. In this technology, named SPS(Struts as Permanent System), retaining wall is installed first and excavation proceeds until the first level of bracing is reached. Braces used as struts during excavation will serve as permanent girders when buildings are in operation. Simultaneous construction of underground and superstructure can proceeds when excavation ends with the last level of braces being installed. In this paper, construction sequence and the calculation concept are explained in detail with some photo illustrations. SPS technology was applied to three selected buildings. One of them was completed and two others are being constructed Many sensors were installed to monitor the behavior of retaining wall, braces as column in terms of stress change and displacement. Adjacent ground movement was also obtained. These projects demonstrate that SPS technology contributes to the speed as well as the economy involved in construction.

• 한국지구물리탐사학회:학술대회논문집
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• 2001.09a
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• pp.23-33
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• 2001

Soil and groundwater contamination is an emerging national issue in recognition of the potential adverse impact to human health and ecosystem. In a recent registration, property owner's liability was addressed on the damages to neighbor's soil and groundwater caused by contaminant-plume migration. Soil and groundwater remediation is a technical and engineering project. But, the scientific and technical solutions for the project have been greatly influenced by social and political movement in the country. Governmental sectors, including local and central, should actively engage on this important issue through long-term planning and public investments. Government made regulations to prevent soil and groundwater contamination, not to punish private sector that has no technical and financial capability for solving such problems.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1325-1325
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• 2024

This research presents a joining system that changes an irregularly shaped material into a member that can be joined and disassembled as a single unit by attaching 3D printed joints. In extreme environments, including extraterrestrial environments, it takes much time and costs to supply materials from Earth. In addition, when living and working in such environments for long periods, a technology enabling the use of locally accessible materials or elements brought to the site for different purposes is essential to realize the construction based on the idea of In-Situ Resource Utilization (ISRU). This research proposes a joining system inspired by the traditional Japanese wooden joinery Kigumi. By integrating Kigumi's excellent features, such as high construction performance, disassemble performance, and mechanical performance, with 3D printing and 3D scanning technologies, the proposed joining system aims to enable irregular-shaped elements to be assembled and disassembled from one another without any fasteners (e.g., bolts, nails, and adhesive). Prototypes of the proposed joints, which apply the Japanese Koshikake-Ari-Tsugi technique, were printed by an additive manufacturing-type desktop 3D printer, then the investigation focused on determining the optimal clearance for the joint. Based on the results, a simple mockup was constructed. Its constructability and mechanical performance were examined. The findings revealed that the joints applying the traditional Japanese Kigumi were printable by the additive manufacturing-type desktop 3D-printer with proper clearance settings, and the proposed joining system shows high performance in construction, including disassembly. The findings provide insights into the feasibility of desktop 3D printing construction in extreme environments.