• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.316-323
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• 2023

The need for sustainable waste management has intensified the focus on recycling prestressed concrete sleepers used in railways. Given their high volume and environmental impact at the end of their service life, finding efficient recycling methods is crucial. This study explores current recycling approaches, particularly mechanical techniques, evaluating their advantages, limitations, and economic feasibility. Finally, an example of mechanical recycling was performed. The analysis results of the resulting recycled aggregates are suggested. Then, the non-cement concrete mixtures with recycled aggregates were designed, and their strength development was analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.865-871
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• 2023

Domestic urban railway are operated by urban railway operating public enterprises, which are owned by the 6 major metropolitan local governments and private operating companies, which are established under the Private Investment Act. Among urban railway operating companies, several public enterprises that operate urban railways with many experience, performance, human resources, and public nature are making efforts to promote overseas business. Therefore, this study examines the outlook for railway and urban railway overseas business, and provides implications for the overseas business approach of domestic urban railway operating public enterprises through data research and comparative analysis on the overseas business approaches and overseas business characteristics of domestic and foreign urban railway operating public enterprises. The results were derived and suggestions for the direction of overseas business were presented. I expect that suggestions will serve as a reference for domestic urban railway operators to promote overseas projects with preparation, implementation plan and direction.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.1
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• pp.163-174
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• 2024

Currently, the urban railway operating agency is improving the emergency telephone in operation into an IP-based "trackside integrated interface communication facility" that can support a variety of additional services in order to quickly respond to emergency situations within the tunnel. This study is based on this Analyze the needs of various stakeholders regarding the design of a system architecture that establishes an IoT sensor network environment to detect abnormal situations in the tunnel and transmits the collected information to the control center to predict disaster situations in advance, and defines the system requirements. In addition, a scenario model for disaster response was provided through the presentation of a service model. Through this, the perspective of responding to urban railway disasters changes from reactive response to proactive prevention, thereby ensuring safe operation of urban railways and preventing major industrial accidents.

• Journal of the Korean Geosynthetics Society
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• v.6 no.3
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• pp.17-23
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• 2007

To construct an ideal geosynthetic reinforced soil retaining wall (GRS-RW), the facing of the wall should be flexible enough to accommodate a large deformation of the supporting ground and to develop the large tensile force in reinforcements during wall construction as long as the stability is ensured, but should be rigid enough to be stiff and stable as well as durable and aesthetically acceptable for a long life time when the wall is in service. Facing conditions during the construction and service of the wall are quite different. So it is difficult to be satisfied all these conditions with the current construction method which is mainly used in reinforced wall construction in Korea. Most of this contradiction could be solved by the staged construction procedure. According to the results of cases and references analyses, stage construction procedures make it possible to accommodate large deformation of the supporting ground and backfill without losing the stability of the wall, and to derive the tensile strength of reinforcement causing deformation of the facing. When the facing is a full-height rigid one, it also appeared almost impossible to occur a local shear failure of the active zone, and pull-out failure of reinforcements. Therefore, GRS-RWs having a full-height rigid facing have been constructed by the staged construction procedures that matched well with the theory of reinforced soil, which had outstanding stability and durability, and thus could be used for railways and bridge abutments in Korea in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.907-913
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• 1994

The design of railroad bridges differs from road bridges because of the interface between track structure and bridge structure. The track generally consists of Continuous Welded Rail(CWR) which is fixed by fasteners to the sleepers embedded in the ballast. The ballast provides the interface between the track structure and the bridge structure. Large longitudinal forces can develop from the temperature variation in rail and bridge structure. These longitudinal forces are specially important for long bridges because the bridge layout for span length, pier dimensions and arrangement and type of bearings can be governed by these forces. This report provides a comparison of longitudinal track forces determined by analysis and actual measured track forces. In recent practice the longitudinal track force for European railways is analyzed using a finite element analysis method. This method is very time-consuming and requires the detail design of the bridge to be complete. Redesign is required if the design criteria for longitudinal track forces are not satisfied. There is a need to develop a simple analysis method considering the large number of bridge structures and a relatively short design time on the Korean High Speed Rail Project. The analysis results presented herein, based on a simplified analysis, show good agreement with those obtained by finite element analysis, as well as with those measured on an actual track. The proposed analysis method is particularly useful for the preliminary design of bridge structures.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.661-670
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• 2016

In 2000, post-construction evaluation was introduced for the purposes to evaluate demand, cost, and construction period of public construction projects and to reduce errors of public order agencies. However, pricing guide of post-construction evaluation has not been established, which becomes a cause of quality degradation of post-construction service and conflict occurrence. This study suggests the pricing guide in the form of percentage of construction cost method and cost plus fee method based on data of post-construction evaluation. This study investigates the construction costs and service costs for post-construction evaluation and conducts the comparative analysis of 'percentage of construction cost method' and 'cost plus fee method.' The analysis result shows 'cost plus fee method' is more accuracy than 'percentage of construction cost method.' In particular, cost plus fee method includes various correction coefficients, such as distance, area, and integration, in order to reflect the project characteristics of each infrastructure, and suggests linear construction (roads, railways), nonlinear construction I (housing and industry complex), and nonlinear construction II (airports, seaports, dams, water and sewage).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8516-8524
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• 2015

Track irregularities can be evaluated not only directly by track inspection but also indirectly by measurement of carbody accelerations and many researches are being conducted. Carbody accelerations were measured on the Kyeongbu high speed railway and France high speed line to investigate the situation of the track maintenance at Korea high speed line by using indirect method. Digital signal processing for the measured acceleration data were conducted according to UIC518 code. Since the vehicle speed affects the car body acceleration, the lateral and vertical acceleration of the car body were classified according to the vehicle speed and the distribution characteristics of these acceleration were investigated and evaluated by UIC518 criteria. Finally, the running behavior of KTX on Korea high speed railway were compared with that on France. Distribution characteristics of these acceleration were evaluated and discussed in terms of the track maintenance in Korea high speed line.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.26-33
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• 2007

Social cost has been increased by traffic accident and congestion since early 1990s. The construction of roadways and railways has been suggested as countermeasures. However, ITS has finally introduced as a logical solution because the expenses of infrastructures are costly. The data collection field has developed through numerous researches and pilot projects. However the information provision field does need a lot of study. The traffic information broadcasting whether simple traffic information or the value-added information has been available via radio, television and internet which does not require tremendous investment compared with data collection stage. Therefore, this study reviews the suitability of the gadget service usually offered by window vista users which is the result of the development of technology and the changes of internet environment. It also suggests to using the RSS(Really Simple Syndication) manner as a basic method to provide the traffic information based on the needs of user in order to enhance the usability of traffic information. For this, this study analyzes the current methods and techniques of traffic information service which is widely available by local governments and companies and suggest possible changes and methods in order to provide Gadget-based service to the public.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.47-56
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• 2007

Recently, tunnels are increasingly constructed in this country with the increased construction of highways, high-speed railways and subways. Shotcrete is one of the major processes in the tunnel construction. Many problems, however, exist in the current shotcrete practice. The purpose of the study is, therefore, to explore the trobles in the current shotcreting practice, and to develop high-quality silica fume shotcrete. For the purpose of security a long-term durability of shotcrete, this study conducted combined deterioration tests. In this study, a combined deterioration test in consideration of a variety of deterioration factors were proceeded. Especially, micro-silica fume that was used frequently in overseas because of a outstanding strength-promotion effect was applied to combined deterioration test, and a long-term durability of shotcrete was investigated according to additions mixing. As a result of test, the shotcrete mixed Micro-silica fume showed a good deterioration quality compared with the other mixes. And is shows that the Micro-silica fume has an outstanding strength-promotion effect and is effective to secure a long-term durability of shotcrete by means of decreasing a deterioration caused by steel fiber mixed.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.465-475
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• 2016

Since inaccurate demand estimation for recent urban rail construction may result in financial burden to cities, precise prediction for operating cost as well as construction costs is necessary to avoid or reduce budget loss of the local or central government. The operating cost is directly related to the public fare and affect a policy to determine the rate system. Therefore, there is a pressing need to develop an estimating model for reliable operating cost of urban railway. This study introduces a new model to estimate the operating cost with new variables. It provides a better prediction in accuracy and reliability compared to the existing model, considering the feature of urban railway. For verification of our model, railway operation data from a few cities for the last five years were comprehensively examined to determine variables that affect the operating cost. The operating cost was estimated in a dummy regression model using five independent variables, which were average distance between stations, daily trains distance, total passenger capacity of a train in a train, driving mode(manned/unmanned), and investment type(financial/private).