• The Journal of Engineering Geology
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• v.31 no.3
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• pp.295-306
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• 2021

This study used numerical modeling to investigate the stability of railway roadbed in areas with various underground cavities and rock conditions associated with mining activities. It compared combined loads from both passenger and freight trains with loads from only passenger trains. Stability was assessed with reference to the Korean government standards for railway subsidence allowance and railway warping repair. Sufficient stability regarding the railway subsidence allowance standard was not achieved when cavities were at depths of <5 m. The criteria for requiring railway warping repair were met when cavities were at depths of <15 m, depending on the rock fracture condition. This study provides the first report on systematic analysis land subsidence related to cavity size and rock fracture conditions associated with mining activities. We expect that this study could serve as an important reference for railway construction in mining areas.

• The Journal of Engineering Geology
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• v.14 no.2
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• pp.223-233
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• 2004

When the groundwater outflow occurs due to tunnel excavation during the road and railroad construction, depletion of groundwater resources, deficiency in the living and agricultural waters, and changes in the surface water flux are expected. The MODFLOW is a most commonly used and three dimensional finite difference model to predict changes in the groundwater system due to the tunnel construction. A conceptual model is one of the most important elements for the proper modeling results. Essential information will not be extracted from an oversimplified conceptual model while excess time and resources with much field data are required for the very complicated one. This study presented a comparison of the modeling results depending on some conceptual models and discussed construction of the efficient conceptual model for reasonable and realistic results in the tunnel modeling.

• Explosives and Blasting
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• v.30 no.1
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• pp.37-51
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• 2012

In this case of "Seongnam~Yeoju double-lanes railroad construction", there were safety facilities which were concerned about damages from vibration and noise. In the project design stage, the rock-splitter method was designed to prevent them. The electronic blasting was considered to improve construction speed and economic value as an alternative tunnelling method, complying with the site's vibration criteria(cowhouse : 0.09cm/sec, residence : 0.2cm/sec). In the environment evaluation report of the eDev, tunnel electronic blasting systems, the blasting pollutions can be managed by the electronic blasting method. The results were successfully conducted with high speed construction without any damages to adjacent facilities.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2006.03a
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• pp.195-203
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• 2006

The crossing construction under railroad have two methods which are cut and cover and trenchless method. first, cut and cover method is an extremely limited method concerning non-running time. Whereas, trenchless method is free from restriction such as train speed and running time, and has the strong points of safe and rapid construction. Front Jacking method, one of the trenchless methods, is frequently applied recently due to its stability during construction and vantage of assuring schedule reliability. The procedure is that after minimizing interlocking friction with structure and earth pressure due to jacking the small steel tube, pulling the precast box manufactured at the field in the ground using PC strand and hydraulic Jack. This method is able to be applied regardless of section size and length of box and condition of ground. And that is also pro-environmental. This paper presents the case of Daejeon E. W. perforate Road Project applied with the Front Jacking method.

• Journal of the Korean GEO-environmental Society
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• v.15 no.11
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• pp.5-12
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• 2014

A slope may fail after construction owing to external factors such as localized rainfall, earthquake, and weathering. Therefore, the grasp of failure probability for slope failures is necessary to maintain their stability. In particular, it is very difficult to detect the symptoms of rock slope failure in advance by using traditional methods, such as displacement due to the brittleness of rocks. However, Acoustic Emission (AE) techniques can predict slope failures earlier than the traditional methods. This study grasped failure probability of slope by applying AE techniques to a rock slope with a history of collapse. When applying AE techniques to a slope that has a high probability of failure, the grasp of failure probability of the specific location became possible.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.72-83
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• 2015

Underground transmission lines always generate heat and transmit heat through surrounding backfill materials. Therefore, in the design of power lines it becomes a very crucial factor to transfer heat effectively into the neighbouring soils. In this study, in order to enhance field applicability of recycled aggregates for backfill material of transmission lines, quality criteria and construction criteria were proposed, and thermal stability of power lines through field demonstration tests were analyzed. In the field tests, two types of recycled aggregates and sand which is currently used for backfilling were compared in terms of thermal behaviour. Test results showed that recycled aggregates represented similar trends with sand in temperature and moisture content corresponding to time lapse and distance from the heat source. Consequently, recycled aggregates can be utilized for backfill materials of underground transmission lines as a substitute material of sands.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.5-11
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• 2013

This study introduces a densification technique of controlled low strength materials (CLSM) made with coal ashes by pump discharge pressure. Based on a small-scale laboratory test results, unit weight of CLSM around discharge pipe is greater than that of relatively some distant area from discharge pipe. It is also found that densification of CLSM depends on not only mixture rate of pond ash but also fly ash and location of discharge pipe.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.278-283
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• 2006

Koran Government introduced BTL(Build-Transfer-Lease) to provide convenience through early supplying infrastructure and plans to invest 8,315million dollar to 84 projects of 15 BTL type involving official residence and railroad. But some of construction company hates to invest BTL projects because of its low earning rate. In addition if we correctively apply project which partly has profitability to BTL, the earnning rate declines more seriously. So this paper presents BTL+BTO model which operates BTL in the non-profitable parts to improve convenience of users and BTO in the profitable parts to improve earning rate. BTL+BTO model based on operate period was presented and its suitability was confirmed by applting 00 region official residence project.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.64-68
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• 2015

BACKGROUND: Heavy metals (Al, As, Cd, Cr, Cu, Li, Hg, Ni, Pb, and Zn) were analyzed to elucidate the impact of weir construction on their concentrations in sediments of Geum River, Korea. We also attempted to investigate the source of the heavy metals in sediments. METHODS AND RESULTS: For this study, sediments were collected from May through June in 2012. The concentrations of heavy metals except Hg were determined by inductively coupled plasma mass spectrometer, and Hg was measured by automatic mercury analyzer. More clay were accumulated in the furthest stations in the upstream direction starting from the weirs. Most of the heavy metals showed higher concentrations in the most upstream located station of Geumnam Weir. However, high concentrations were not observed in the most upstream stations of the other weirs. The concentrations of Hg and As were much higher in sediments of Gap Stream. CONCLUSION: Gap Stream may be a potential source for high deposits of As and Hg. Presence of the dams may not play an important role in controlling heavy metal concentrations in sediments. It is necessary to monitor heavy metal concentrations for a longer time period to study the effect of environmental changes on heavy metal distribution in Geum River.

• International Journal of Railway
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• v.7 no.3
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• pp.71-79
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• 2014

Subway systems have been a proved method of public transport and are widely used in major cities around the world. However, the time and cost it takes to construct such systems are very high, as it requires underground tunnels. Cities in various countries have implemented monorail systems as public railway transport as it can be more economical and quicker compared to subway systems in terms of construction. In addition, it provides more convenience towards the public as it is not affected to traffic, and also provides an aerial view of the city. However, the overall construction cost for monorail systems is still significantly high, and as a possible solution to further reduce the overall cost, implementation of ground-level stations and wireless power transfer technology has been proposed in this paper. A concept application layout of ground-level stations and wireless power transfer systems has been discussed, using the Daegu monorail Line 3 system as a simulation base. The expected cost for monorail systems implementing ground-level stations and/or wireless power transfer technology has been estimated based on literature survey, and was compared with the current construction cost of Daegu monorail system. Based on comparison, it has shown that implementation of ground-level stations are the most economical, and can be easily implemented for either starting or expanding the monorail line. Implementation of wireless power transfer technology is also economical, but is more feasible when starting a new monorail line as it requires components which will alter the configuration of the train and infrastructure.