• Smart Structures and Systems
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• v.15 no.3
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• pp.683-698
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• 2015

Railroad bridges form an integral part of railway infrastructure throughout the world. To accommodate increased axel loads, train speeds, and greater volumes of freight traffic, in the presence of changing structural conditions, the load carrying capacity and serviceability of existing bridges must be assessed. One way is through system identification of in-service railroad bridges. To dates, numerous researchers have reported system identification studies with a large portion of their applications being highway bridges. Moreover, most of those models are calibrated at global level, while only a few studies applications have used globally and locally calibrated model. To reach the global and local calibration, both ambient vibration tests and controlled tests need to be performed. Thus, an approach for system identification of a railroad bridge that can be used to assess the bridge in global and local sense is needed. This study presents system identification of a railroad bridge using free vibration data. Wireless smart sensors are employed and provided a portable way to collect data that is then used to determine bridge frequencies and mode shapes. Subsequently, a calibrated finite element model of the bridge provides global and local information of the bridge. The ability of the model to simulate local responses is validated by comparing predicted and measured strain in one of the diagonal members of the truss. This research demonstrates the potential of using measured field data to perform model calibration in a simple and practical manner that will lead to better understanding the state of railroad bridges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.53-59
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• 2019

To reduce the vibrations and shocks during the cargo transportation of high value-added goods, the vibration history was measured on the truck transportation section (Asan-Uiwang) and the freight train transportation section (Uiwang-Pusan). The internal vibrations of the container were obtained by attaching acceleration sensors in three axis directions (longitudinal, lateral. and vertical directions) on the front and rear bogies. The rail vibration profile (0.29Grms) proposed in ASTM D-4169 was approximately 50% higher than the truck vibration profile (0.54Grms). The overall vibration was 16% and 33 % lower in the longitudinal and transverse directions, respectively, compared to the ASTM truck transport vibration profile. On the other hand, the vertical vibration measurement history partially exceeded the ASTM truck transport vibration profile over the range, 4 - 15Hz, and over 60Hz. The vibration measurement history of the cargo train was similar to that of the road. The longitudinal and lateral vibration history was lower than the ASTM D-4169 rail vibration profile, while the vertical history was over 30Hz.

• The Journal of Society for e-Business Studies
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• v.13 no.3
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• pp.121-135
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• 2008

Railroad logistics transporting freight by train takes charge of 10 or 20 percent of domestic cargos. Railroad logistics users such as transport companies including shippers or Inland Container Depot(ICD) use electronic document(EDI or XML) or input data through WEB to process railroad logistics business. However, as business environments evolving into e-business, it is required to upgrade the legacy railroad logistics process. As the increase of using ebXML-based schema format, it is also needed to improve the electronic documents based on DTD format into those of XML schema format. This study deals with information standard for railroad logistics to improve the railroad logistics business. To this purpose railroad business processes were re-defined through the standard business process modeling methodology. Information model was also derived by defining railroad logistics activities from business process model. And Business Information Entities(BIEs) were defined to design new electronic documents according to the extracted information model. An improved system architecture for railroad logistics was proposed as well. The results of this study will provide an effective and flexible business flow to railroad logistics business.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.139-157
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• 2007

The purpose of this paper is to analyze the competitiveness of the logistics industry of three countries - Korea, China and Japan - by looking into their logistics industry structure and the related regulations. For this aim, the paper examined the modal distribution of transportation, transport infrastructure, freight cost structure and regulation in transport sector in these countries. Furthermore, this study suggests some proposals for the further cooperation to bring sustainable progress in the logistics sector across Northeast Asia. The main suggestions of this paper are as follows: First, Korean government needs to strategize its options in the logistics industry, the most competitive in the country’s service sector, in upcoming FTA negotiations with China and Japan. Second, Korea needs to foster Busan into a strategic point for the Rail Ferry System and Road Feeder System. Third, Korea should participate in establishing shuttle flight service in Northeast Asia amid exploding flight demand from active economic interchange and tourism industry development.

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.672-684
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• 2016

UIC Codes 714R & 715R recommend the use of line classifications and their usage in maintenance work by employing notional traffic loads. However, the classification has not been applied to local lines and, therefore, a new line classification system based on UIC 714R has been proposed in this study. For this, various classification models of UIC, Germany, and UK have been studied first and equivalent traffic loads based on Korail's report, as well as on train timetables, have been derived. The results of the classifications have been compared with those of major European countries and it has been shown that the proposed classification is equivalent to the average value in the European cases. The line classification can be fully utilized during the decision making process of maintenance work and will also be used to model the Reliability Centered Maintenance (RCM) in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.637-644
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• 2016

This paper is a follow-up to previous papers entitled, "Development of Tunnel-Environment Monitoring System and Its Installation" I [1] and II [2]. The target tunnel of these studies is the Solan Tunnel, which is a loop-type, single-track, 16.7-km-long tunnel located in mountainous terrain and passing through the Baekdudaegan mountain range. It is an ordinary railway tunnel designed for both freight and passenger trains. We analyzed the environmental conditions of the tunnel using temperature and humidity data recorded over approximately one year. The data were recorded using the Tunnel Rough Environment Measuring System (TREMS), which measures environmental data in subway and high-speed train tunnels and is installed in three locations inside the tunnel. Previous studies analyzed environmental conditions inside tunnels located in or near a city, whereas the tunnel in this study is located in a mountainous area. The tunnel conditions were compared with those measured outside the tunnel for each month. Hourly changes during summer and winter periods were also analyzed, and the environmental conditions at different locations inside the tunnel were compared. The results are widely applicable in studies on the thermal environment and air quality of tunnels, as well as for computer analysis of tunnel airflow such as tunnel ventilation and fire simulations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.131-140
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• 2022

Installing Continuous Welded Rail (CWR) is one of the economical ways to resolve the challenges of noise, vibration, and the open-deck steel railway bridge impact, and the SSF method using the interlocking sleeper fastener has recently been developed. In this study, the method employed for determining the optimum vertical stiffness of the sleeper pad installed under the bridge sleeper, which is utilized to adjust the rail height and absorb shock when the train passes when the interlocking sleeper fastener is applied, is presented. To determine the optimal vertical stiffness of the sleeper pad, related existing design codes are reviewed, and, running safety, ride comfort, track safety, and bridge vibration according to the change in the vertical stiffness of the sleeper pad are estimated via flexible multi-body dynamic analysis,. The flexible multi-body dynamic analysis is performed using commercial programs ABAQUS and VI-Rail. The numerical analysis is conducted using the bridge model for a 30m-long plate girder bridge, and the response is calculated when passing ITX Saemaeul and KTX vehicles and freight wagon when the vertical stiffness of the sleeper pad is altered from 7.5 kN/mm to 240 kN/mm. The optimum stiffness of the sleeper pad is calculated as 200 kN/mm under the conditions of the track components applied to the numerical analysis.