• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.833-838
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• 2024

The urban railway sleeper floating track(STEDEF) is a structure that structurally separates the sleepers and the concrete bed using sleeper boots and resilience pads to reduce vibration transmitted to the concrete bed. Recently, the resilience pads of sleeper floating tracks that have been in use for more than 20 years are deteriorating. Accordingly, in order to evaluate the performance of the resilience pad, a static spring stiffness test is being performed after extracting the resilience pad. This evaluation technique is performed after replacing the resilience pad in use. However, the track natural frequency can change depending on the resilience pad spring stiffness and the uplift and subsidence of the concrete bed. In this study, modal testing technique was used to evaluate the track natural frequency. For this purpose, the sleeper boots material, resilience pad spring stiffness, and track natural frequency according to concrete bed uplift and subsidence were measured using modal tests at a laboratory scale. It was analyzed that the natural frequency of the sleeper floating track was directly affected by changes in the spring stiffness of the resilience pad. In addition, the change in natural frequency due to the uplift and subsidence of the concrete bed was also found to be large. Therefore, it is believed that the modal test technique presented in this study can be used to evaluate the resilience pad deterioration and voided sleepers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.2
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• pp.139-146
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• 2013

This study is to update of vibration power generating model and to analyze electromotive force on subway. Analysis of electromotive force using power generation depending on classification of locations which are ballast bed and concrete bed. As the section between Seocho and Bangbae in the line 2 subway was changed from ballast bed to concrete bed, it could be analyzed at same condition, train, section. Induced electromotive force equation by Faraday's law was updated using Bayesian regression and correlation analysis with calculate value and experiment value. Using the updated model, it could get 40mV per one power generation in ballast bed, and it also could get 4mV per one power generation in concrete bed. If the updated model apply to subway or any train, it will be more effective to get electric power. In addition to that, it will be good to reduce greenhouse gas and to build a green traffic network.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.107-115
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• 2011

In this study, the vibration analysis of the underground box structures induced train movement is studied. In order to perform these analysis, dynamic data, which was measured when subway is in service, are gained by attaching accelerometers on the structure such as lower beam, lateral wall and upper slab. Also, accelerometers are attached on the lower beams and side walls of the gravel ballast and concrete ballast sections in order to compare vibration due to ballast materials. The vibration results of upper slabs and lower beams reveal that the vibration on the upper slabs is greater than the lower beams. Also, the results of the crack gauge on the upper slab show that crack width dose not change due to vibration, These means that the effect of the vibration on the structure is very limited. In order to evaluate the vibration of the structure, acceleration unit is converted to velocity unit comparing with the existing velocity data gained from the platforms.

• 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.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.172-178
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• 2012

Superimposition of vertical and transition curves is not allowed for all types of tracks in Korean regulation of railway construction. However, this criterion has been established on the basis of difficulty of maintenance of the ballasted track. Comparing with the ballasted track, the concrete slab track has the advantage of maintenance and structural, which allows the superimposition of vertical and transition curves when it satisfies the criteria of running safety and riding comfort. In this study, running safety, ride comforts and track acting forces were analyzed and compared by numerical analysis using VAMPIRE program when the vertical and transition curves are superimposed for the ballasted track as well as the concrete slab track. From the analysis results, it was found that running safety, riding comforts and track acting forces in case of superimposition of vertical and transition curves for the both tracks meet all of the criteria. Therefore, although superimposition of vertical and transition curves for the ballasted track is not allowed because of a lot of maintenance works, it can be applied to the concrete slab track considering the advantage of maintenance and structural safety.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.458-465
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• 2018

Purpose: Concrete track that affects on railway safety can detect cracks using image processing technique. However, since a condition of concrete track and surface noisy are obstructed to detect cracks, there is a need for a way to remove them effectively. Method: In this study, we proposed an image processing to detect cracks effectively for Korean railway and verified its performance through experiment. We developed image acquisition system for capture a railway concrete track and acquired railway concrete track images, randomly selected 2000 images and detected cracks in the image process using proposed Gabor Filter Bank methods. Results: As a result, 94% of detection rate are matched to the actual cracks in same quality and format railway concrete track image. Conclution: The crack detection method using Garbor Filter Bank was confirmed to be effective for crack image including noise in the Korean railway concrete track. This system is expected to become an automated maintenance system in the existing human-centered railway industry.

• Computational Structural Engineering
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• v.14 no.2
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• pp.30-38
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• 2001

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.517-522
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• 2021

In this study, the causes of damage to the concrete sleepers in a ballast track with under sleeper pads attached to the base of the sleepers installed in the sharp curved track(R=180m) of the urban railway bridge were analyzed. The damage types of concrete sleepers were investigated, and the correlation with track irregularity was reviewed. Also, stress generated in the concrete sleeper was reviewed through structural analysis. As a result, most of the cracks of the sleepers occurred in the section with severe track irregularity. In addition, as a result of the analysis, the stress generated in the track components and the sleepers was found to be reduce in the fastening system using the 4-anchor.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.248-255
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• 2011

Impact factor of concrete and ballast track which has been used in Korea railway was applied to equation (1+0.513V/100) from AREA. As the use of this equation, overcapacity of track design might be occurred. Therefore, this study compared impact of ballast track (well, bad) and concrete track (sleeper embeded system, rail floating and sleeper floating) by field test to analyzing dynamic effect of track structure's characterstic and wheel load on service line. In addition, it suggested a method to generate reasonable impact factor on each track type.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.75-82
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• 2016

As spreading of train concrete ballast leads to the increase resounding friction noise, an porous sound absorbing block is applied in urban train tunnel as a counterparts against the friction noise. Three steps of major variables tests for an optimal mix design of the block are conducted to pursue the light weight of the block. Pilot property tests of the block for the cases of the fly-ash only as lightweight aggregates are carried satisfying KRT(Korean Rail Transit) and new KRS(Korean Railway Standards). Based on the results of pilot tests, required structural strength and admixture effects are evaluated. Additionally, typical lightweight aggregates are replaced so that lightweight and strength are improved for serviceability of poor working conditions and proper maintenance in urban train tunnel.