• Geomechanics and Engineering
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• v.34 no.1
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• pp.87-102
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• 2023

The cover plate and the building loads often make the semi-covered deep excavations with existing buildings bearing asymmetric load, presenting different deformation characteristics with normal excavations, which is not absolutely clear in current studies. Based on a typical engineering, the building storeys, the basement storeys, the pile length, the existence of the cover plate (CP) and the depth of the diaphragm walls (DW) were selected as variables, and 44 groups of simulation were designed to study the influence of existing buildings and the semi-covered supporting system on the deformation of the excavations. The results showed that the maximum lateral displacement of DW, δ_hm, and the depth of δ_hm, H_m, are affected seriously by the building storeys and the basement storeys. Asymmetric structures and loading lead to certain lateral displacement of DW at the beginning of excavation, resulting in different relationships between δ_hm and excavation depth, H. The maximum surface settlement outside the pit, δ_vm, increases significantly and the location, d_m, moves away from the pit with the building storeys increases. δ_vm has a quadratic correlation with H due to the existing buildings. CP and building load will affect the style of the lateral displacement curve of DW seriously in different aspects.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.297-303
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• 2016

This paper introduces auxiliary power supply systems (APS) for railroad applications and proposes a new power conversion structure for highly-efficient and lightweight APS systems. The proposed structure focuses on an improvement of the power density in APS. It eliminates unnecessary power conversion stages in the conventional APS structure by modulating the dc/dc converter circuit and the structure of the system. The dc/dc converter circuit used in the proposed structure is based on a multi-level half-bridge converter, a widely used topology in railroad APS applications; a flying capacitor is newly added to the conventional circuit. The added capacitor is used not only to enhance the soft switching condition of the switches, but also so that the new pantograph will have a side voltage source of a battery charger in the APS structure. Since the battery charger uses the pantograph side voltage source in the proposed structure, rather than using the output of the main dc/dc converter in the conventional structure, the size and efficiency of the main dc/dc converter are reduced and increased, respectively. To verify the effectiveness of the proposed structure, simulation results will be presented with metropolitan transit APS specifications.

• Spatial Information Research
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• v.10 no.2
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• pp.247-261
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• 2002

There are much damage of people and property because of heavy rain every year. Especially, there are problem to major facility such as dam, bridge, road, tunnel, and industrial complex in the ground stability. So the counter plan for landslide or ground failure must be necessary In the study, the technique of regional landslide susceptibility assessment near the Ulsan petrochemical complex and Kumgang railway bridge was developed and applied using GIS. For the assessment, the geological structures such as bedding and fault were surveyed and the geological structure, topographic, soil, forest, and land use spatial database were constructed using CIS. Using the spatial database, the factors that influence landslide occurrence, such as slope, aspect, curvature and type of topography, texture, material, drainage and effective thickness of soil, type, age, diameter and density of forest, and land use were calculated or extracted from the spatial database. For application of geological structure, the geological structure line and fault density were calculated. Landslide susceptibility was analyzed using the landslide-occurrence factors by probability method that is summation of landslide occurrence probability values per each factors range or type. The landslide susceptibility map can be used to assess ground stability to protect major facility.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.384-389
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• 2006

The needs for Light Railroad Transit(LRT) have been increased due to the heavy traffic congestions in large cities like Seoul, Korea. Korean government is seeking the LRT system development (including planning, designing, construction, and maintenance and operations) in terms of public-private-partnership (PPP). At the private sector side, it is crucial to estimate the life cycle cost (LCC) to project the cash flow during the O&M period. Since the most construction and O&M cost of LRT project is at the bridge construction, a cost analysis model and a cost breakdown structures (CBS) on LRT bridges are discussed through in depth literature reviews. Construction and maintenance cost of bridges are collected and analyzed. LCC is analyzed by types of bridge superstructures and historical data of repair and rehabilitation (R&R) is investigated. There have been scarce number of LCC analysis on railway bridges. This research delivers a well-defined CBS and maintenance cost data, which will be a great benefit to the systematic maintenance strategy development for railroad bridges.

• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.1-24
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• 2016

Northeast Asia is changing rapidly, including becoming an increasingly important part of the world economy. Various logistical systems and networks are being established in this area, including South and North Korea, China, Japan, Russia, and Mongolia. Thus, a new systematic logistical network and development strategy is required. The division of the Korean peninsula has for a long time made the region ineffective in terms of land logistics. South Korea's connection to Eurasia is blocked by North Korea, which means it is essentially treated as an island. Furthermore, South Korea does not have an efficient logistics system or effective vision and strategy. Northeast Asia has the potential to be one of the largest economic communities in the world, similar to the EU and North America. Thus, a united Korea can play an important role as the land bridge of Northeast Asia and the logistical hub of the region. This study reviews the logistical position, tasks, and problems of the Korean peninsula and suggests a desirable development strategy and vision. Specifically, after examining the conditions for a land logistical system, focusing on railways, this study proposes several future-oriented development strategies and tactics that will position the peninsula as a logistical hub in Northeast Asia. We anticipate that this study will serve as the basis for future research that will investigate the topics presented here in more detail.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.51-57
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• 2011

Irregular distributions of limestone cavity in Gang-Won province area may cause unexpected accidents from reduced serviceability or failure of structure. It is requested that an appropriate ground reinforcement method should be used to improve bearing capacity of structure, and the method should also be satisfied with environmental requirements. Among several methods used for foundation constructions in cavity area, Rod Jet Pile(RJP) method has been widely used. While the RJP method was used to improve bearing capacity for the railway bridge foundations, water pollutions of drinking water as well as fishery located adjacent to this project area were occurred. The main reason of the water pollution was cement runoff used in cement mortar during injecting material in RJP method. Laboratory tests were performed to prevent water pollution. The compaction mortar method using low movable material was selected for this project. The quality of water at a fishery adjacent to the site and the compressive strength of cores taken from the construction site were measured. Test results show that the water pollutions was minimized, and the average compressive strength of foundation material was over 5 MPa. As a result of this study, compaction mortar method can be used to ensure the bearing capacity of foundation and to prevent environment pollutions.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.633-640
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• 2023

In this study, numerical analysis was performed based on field investigation to derive an appropriate reinforcement method by analyzing the displacement behavior characteristics of concrete blocks generated in the direct fixation track on the bridges of the serviced light rail transit. The track of this study was a direct fixation track on a sharp curved track, and the problem of movement of the concrete blocks installed on the bridge deck in the longitudinal and lateral directions occurred. In this study, based on the finite element model using 3D solid elements, the behavior of the direct fixation track that could be occurred under operating load conditions was analyzed. In addition, the reinforcement effect of various reinforcement methods was analyzed. As a result of analyzing the lateral displacement before and after reinforcement, it was analyzed that the maximum lateral displacement after reinforcement under the extreme lateral wheel loads significantly decreased to about 3% (about 0.1mm) compared to before reinforcement. In addition, as a result of examining the generated stress of the filling mortar, bridge decks, and reinforcing bar, it was analyzed that all of them secured a sufficient safety factor of 2.6 or higher, and the optimal conditions for the reinforcement method were derived. Therefore, it is judged that the number of anchoring reinforcements and symmetrical anchor placement reviewed in this study will be effective in controlling the occurrence of lateral displacement of concrete blocks and securing the structural integrity of bridges and concrete blocks.

• Steel and Composite Structures
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• v.36 no.4
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• pp.481-492
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• 2020

To study the rail mapped deformation caused by the pier settlement of simply - supported bridges with China Railway Track System III (CRTS III) slab ballastless track (SBT) system under the mode of non-longitudinal connection ballastless track slab, this study derived an analytical solution to the mapped relationships between pier settlement and rail deformation based on the interlayer interaction mechanism of rail-pier and principle of stationary potential energy. The analytical calculation results were compared with the numerical results obtained by ANSYS finite element calculation, thus verifying the accuracy of analytical method. A parameter analysis was conducted on the key factors in rail mapped deformation such as pier settlement, fastener stiffness, and self-compacting concrete (SCC) stiffness of filling layer. The results indicate that rail deformation is approximately proportional to pier settlement. The smaller the fastener stiffness, the smoother the rail deformation curve and the longer the rail deformation area is. With the increase in the stiffness of SCC filling layer, the maximum positive deformation of rail gradually decreases, and the maximum negative deformation gradually increases. The deformation of rail caused by the pier settlement of common-span bridge structures will generate low-frequency excitation on high-speed trains.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.5
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• pp.57-65
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• 2004

This study was carried out to measure the growth and photosynthesis of Iris pseudoacorus, the reduction rate of nitrogen(T-N) and phosphoric acid($P_2O_5$) from soils, and the increase rate of two substance into plants which cultivated at waterway soils of different concentration of two substance. The results are summarized as follows; 1. The contents of nitrogen and phosphoric acid at waterway soils of Mangyeong river showed the highest level in the around Samrye railway bridge where was located in the downstream and sewage of stock raising flowed in 2. The Iris pseudoacorus which cultivated at waterway soils showed the leaf and root growth of 43~50 and 9~13cm, respectively. And the growth was higher in the waterway soils contained high level of nitrogen The rate of photosynthesis was $3.5-5.9{\mu}mol\;m^{-2}s^{-1}$ ranges and this rate increased from the end of June to August and then decreased. The rate of photosynthesis was higher in waterway soils contained high nitrogen regardless of seasons. 4. The Iris pseudoacorus removed nitrogen and phosphoric acid from waterway soils about 19~21% and 13~15%, respectively. The Iris pseudoacorus was effective to remove nitrogen more than phosphoric acid. And the waterway soil which included high concentration of two substance showed highly removal 5. The results of Iris pseudoacorus vegetation in the waterway soils showed that nitrogen and phosphoric acid of inside plant increased with 0.2-1.0% and 0.01-0.10% ranges, respectively. The contents of nitrogen and phosphoric acid in plants were increase in the soils of higher contents of nitrogen and phosphoric acid, and the rate of increase of nitrogen and phosphoric acid was higher at roots than leaves.

• Journal of the Korean Society of Safety
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• v.21 no.4 s.76
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• pp.73-84
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• 2006

Standard safety management cost system was established in 1988 as a decree Number of 88-13, first time. And then, it has been revised fourteen times, up to now. A lot of practical investigations have been made for the revision but many problems at sites are continued to be put out so that it should be revised. This study is to find out hazard level of each work kinds through questionnaire and interview and investigate analyze the status which standard safety management costs have been used. Also, this study is to show reasonable rates of standard safety management costs in construction industry and to set up countermeasures against those problem after reviewing its status in korea with in Japan and Europe. Budget and actually performed amount of safety management costs in this study are investigated. costs for temporary work which is clarified in Japan is collected in order to compare domestic cost rate with Japanese one related to the total project amount. This study is to investigate eleven project kinds of domestic system, first, and to investigate eleven items of apartment bldg, office, civil work such as bridge, tunnel, dam, plant etc, secondly. Additionally, three items of gymnasium, railway, particular steel tower are investigated in this study. Also this study is to investigate and analyze performed costs of presently processing worker finished work so that it shows a new reasonable rate against standard safety management costs in construction industry, in order to make basical data and material to be systemized.