• International conference on construction engineering and project management
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• 2017.10a
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• pp.42-51
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• 2017

Due to the high degree of mechanization and the good environmental benefits, the prefabricated buildings are being promoted in China. The construction site layout of the prefabricated buildings has important influence on its safety benefit. However, few scholars have studied the safety problem on it. Firstly, in order to give a follow-up study foreshadowing the characteristics of prefabricated buildings are analyzed, the research assumptions are given and three types of safety buffers are established. And then a mult-objective model for the prefabricated buildings site layout is presented: taking into account the limits of noise, the coverage of the tower crane and the possibility of exceeding boundaries and overlapping, the constraints are and designed established respectively; Based on the improved System Layout Planning (SLP) method, the efficiency\cost\safety interaction matrices among the facilities are also founded for objective function. For the sake of convenience, a hypothetical facility layout case of the prefabricated building is used, the optimal solution of that is obtained in MATLAB with particle swarm algorithm (PSO), which proves the effectiveness of the model presented in this paper.

• Geomechanics and Engineering
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• v.38 no.1
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• pp.69-77
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• 2024

The development of shield-driven cross-river tunnels in China is witnessing a notable shift towards larger diameters, longer distances, and higher water pressures due to the more complex excavation environment. Complex geological formations, such as fault and karst cavities, pose significant construction risks. Real-time adjustment of shield tunneling parameters based on parameter prediction is the key to ensuring the safety and efficiency of shield tunneling. In this study, prediction models for the torque and thrust of the cutter plate of ultra-large diameter slurry shield TBMs is established based on integrated learning algorithms, by analyzing the real data of Heyan Road cross-river tunnel. The influence of geological complexities at the excavation face, substantial burial depth, and high water level on the slurry shield tunneling parameters are considered in the models. The results reveal that the predictive models established by applying Random Forest and AdaBoost algorithms exhibit strong agreement with actual data, which indicates that the good adaptability and predictive accuracy of these two models. The models proposed in this study can be applied in the real-time prediction and adaptive adjustment of the tunneling parameters for shield tunneling under complex geological conditions.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.551-557
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• 2007

This paper describes a study on the permeability reduction of the riverbed ground during urban railway tunnel construction. The research is mainly concentrated on the study of the grouting or injection methods among permeability reduction methods which can be adapted in the riverbed ground. Firstly, the various grouting methods are theoretically reviewed and compared based on the previous research papers and case study results. It is also evaluated the grouting methods in view of a safe construction of the river crossing railway tunnel. Baced on the literature review and previous construction data, the design technology of grouting methods considering the long term hydro-geological behaviour in the riverbed, is suggested. Two injection methods namely, Natural Durable Stabilizer(N.D.S) and Space-Multi Injaction Grouting(S.M.I) methods, are introduced as new approach methods which can be adopted to modify the riverbed ground. In order to evaluate the ground that grouted and modified by the N.D.S and S.M.I method, the pilot test programmes including the field and laboratory permeability tests, are carried out in the river crossing tunnel construction sites. The results obtained from pilot test programme, are also reviewed. In conclusion, the grouting efficiency of the S.M.I method using the non-alcalimeter silica sol is better than that of NDS method using cement. In addition, it hopes that the research results are contributed to develop the grouting design technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.503-510
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• 2020

Eco-friendly mountain railways operate on concrete rack tracks embedded on existing sharp curved and steep roads to preserve the environment in mountainous areas. Owing to the narrow roads, single lines are inevitable, and many branches are required. In branches, previous switchers and heating devices cannot be applied, because of the limited spacing for the rack and the slow removal of thick ice. To solve these problems, a switch and a heating device have been developed. The switcher changes the line by moving the block of concrete track with hydraulic actuators. The lack of discontinuity reduces the derailment risk and makes locking simple. The heating device uses high frequency induction coils to increase the efficiency and melt the thick ice rapidly. The prototype switcher and heating device were produced and operated to prove their performance. The heating device yielded a 10 times greater efficiency than the previous one. The switcher and heating device are the essential core technologies for the operation of mountain trams in winter and contribute to the spread of mountain railways to domestic or foreign resort areas by enhancing safety and efficiency. In addition, they can provide transportation rights to local residents in poor winter traffic, and bring about tourism and local economic growth.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.408-412
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• 2012

Recently, new climate change mechanism after 2020 year has been accepted with the parties, and so government is pushing ahead the GHG reduction policies to achieve the effective results. Especially, it is essential to enhance the role of railroad in the public traffic system as well as to develop new cars with high energy efficiency for the GHG reduction of transportation sector. Thus, the calculation method of GHG emission of railroad should be established to manage the emission continuously. In this study, the calculation method of GHG emission of railroad was defined with Tier level considering its emission sources to refer to 2006 IPCC guideline for national GHG inventories. Also, the GHG emission of railroad at Tier 1 level was investigated using the activity data related to the amount of diesel and electricity consumption from 2008 to 2010. As a result, total GHG emission in 2010 was about 2,060 thousands ton CO2e, which have 73% of electricity and 27% of diesel. In future, the plans on the GHG reduction of railroad will be accomplished by the analysis of the detailed trends on the basis of the emission management of Tier 3 level under operating patterns. Therefore, it is important to develop the specific GHG emission factors of railroad in advance.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.833-843
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• 2016

Recently, in the field of rail freight transportation, the number of trains dedicated for shippers has been increasing. These dedicated trains, which run on the basis of a contract with shippers, had been restricted to the transportation of containers, or so called block trains. Nowadays, such commodities have extended to cement, hard coal, etc. Most full freight cars are transported by dedicated trains. But, for empty car distribution, the efficiency still remains questionable because the distribution plan is manually developed by dispatchers. In this study, we investigated distribution models delineated in the KTOCS system which was developed by KORAIL as well as mathematical models considered in the state-of-the-art. The models are based on optimization models, especially the network flow model. Here we suggest a new optimization model with a framework of the column generation approach. The master problem can be formulated into a transportation problem with additional constraints. The master problem is improved by adding a new edge between the supply node and the demand node; this edge can be found using a simple shorted path in the time-space network. Finally, we applied our algorithm to the Korean freight train network and were able to find the total number of empty car kilometers decreased.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.717-726
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• 2016

Emergency tracks are necessary in case a broken down train evacuates, a train needs to make way for a faster train behind it, or a train suddenly stops and following trains must avoid colliding with it. Magnetic Levitated (maglev) Trains can change track to enter an emergency track using a segmented switch or a traverse switch. On a traverse switch, a train can change its track when the part of the track that the train is on moves to the other track. Currently manufactured Maglev trains have two bodies and the total length is 25 meters. If a traverse switch is used, it will only require 30 meters of track to move the train to the other track, so, when it comes to efficiency of costs and space, the traverse switch surpasses the articulated switch. Therefore, in this paper, an optimized design to secure structural safety and weight lightening is suggested. To achieve these results, the heights of the piled concrete and girders which are both placed on the top of the traverse switch, are set as design variables. The Finite Element Method (FEM), in application of kriging and in the design of the experiments (DOE), is used. Maximum stress, deformation, and structural weight are compared with the results, and through this process structural safety and weight lightening is proven.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2983-2988
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• 2010

The train control system used in Gyeongbu-line is classified in ATC, IXL and CTC. Domestic railway signaling systems are being developed by electrification. In these systems the electrification of interlocking reaches 57% and the safety equipments of railway crossings in trackside devices have completed their development into an integrated system. Block systems of all the existing sections have not yet electrified and integrated so that they need a number of complement in terms of construction and maintenance. For ABS currently used in existing domestic lines, and LEU being installed in Gyeongbu and Honam lines, although a train is controlled by the signaling information of the same train in the same location, the system is separately installed so that the same information is separately divided and transmitted at the each distinct system. Therefore, in the conventional ABS and LEU, there are a lot of duplicate installed compartments such as lamp detection and a power supply unit. Hence, we have a lot of problems: for maintenance, a lot of manpower and costs need to be invested and the overall manufacturing costs get higher, as well as the construction costs by duplicate. Therefore, this paper suggest design to develop an integrated electronic Block Control Unit by the integration of the currently used ABS, and communication and electronic technology. We are to monitor and manage the block systems in the corresponding station by integrating. And we are to transmit information together with LEU, which is an ATS wayside transmitter.

• Journal of Environmental Health Sciences
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• v.38 no.1
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• pp.51-56
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• 2012

Objectives: High concentrations of airborne particulate matters (PM) can affect the health of passengers using public transportation. The objectives of this research were to develop a PM control system for a railway cabin and to evaluate the performance of the device under conditions of an actual journey. Methods: This study measured the concentrations of $PM_{10}$ and $PM_{2.5}$ simultaneously in a reference cabin and a cabin with the PM control device. Results: The average $PM_{10}$ concentration in the reference cabin was 100 ${\mu}g/m^3$, and the $PM_{10}$ concentration in the cabin with the control device was 79 ${\mu}g/m^3$. While the overall control efficiency of the control device was 15.4%, reduction was more effective for peak $PM_{10}$ concentration. However, $PM_{2.5}$ levels did not differ greatly between the reference cabin and the cabin with the control device. The ratio of $PM_{2.5}$ to $PM_{10}$ was 0.37. $PM_{10}$ concentrations in cabins were not associated with ambient concentrations, indicating that the main sources of $PM_{10}$ were present in cabins. Additionally, average $CO_2$ concentration in the cabins was 1,359 ppm, less than the maximum of 2,000 ppm set out by the Korean Ministry of Environment's guideline. The $CO_2$ concentration in cabins was significantly associated with the number of passengers: the in-cabin concentration = $23.4{\times}N+460.2$, where N is the number of passengers. Conclusions: Application of the PM control device can improve $PM_{10}$ concentration, especially at peak levels but not $PM_{2.5}$ concentration.

• Journal of the Korean Society for Railway
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• v.19 no.1
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• pp.38-45
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• 2016

The power transformation system of High Speed rolling stocks like KTX-Sancheon has shown excellent control capacities in the areas of riding comfortability, switching efficiency, safety and energy consumption due to technical developments in power-electronics, high speed & large scale integrated semiconductors and microprocessors. However, harmonics from IGBT, a high speed switching device used in the Convertor & Invertor equipment of rolling stocks have given rise to various problems in transformer substations, signaling systems, data transmission systems and facility monitoring systems. Especially, TI21 non-insulated track circuits have malfunctioned due to the influence of returning current harmonics which were generated at around of integer times of the number of power transformation equipment in the frequency domain. This paper, measures and analyzes various schemes to analyze the traveling path of the returning current harmonics generated due to the relationship between the rolling stocks and track circuits on site. Ultimately, theseschemes will be used to design high speed rolling stocks, AF track circuits and a common grounding network.