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Daejeon, South Korea

Kim J.-W.,KORAIL Research Institute | Yu S.-N.,Korea Atomic Energy Research Institute
International Journal of Precision Engineering and Manufacturing | Year: 2013

The main purpose of this paper is to select a design variable that can maintain a stable current collection despite changes of span lengths during operation. For the purpose of improving the current collection of the pantograph system, we used a robust design method with tools to select an optimal design variable. As the robust design requires a simulation of selected factors based on the tables of an orthogonal array, it is necessary to configure a numerical model for analyzing a pantograph system. In this study, we induced an equation of motion by implementing a linear 3DOF model in terms of system interpretation. Then, we figured out a time varying stiffness of catenary within a given speed range by configuring a finite element model of the catenary system, and analyzed the contact force by span and speed. Then, we intended to select an optimal combination of design variables that can improve the current collection while high-speed trains are driving. To that end, we came to utilize the robust design method as a kind of optimization technique. Robust design includes the array of signal factors and control factors onto the tables of an orthogonal array and analyzes an S/N ratio and sensitivity as a result of output response characteristics for each design variable level. According to these results, we selected an optimal level of design variables that are likely to improve the current collection. Consequently, we conducted a simulation on selected design variables to check if they have an effect on reducing vibration. By doing so, we managed to confirm their reproducibility. © 2013 Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg. Source

Chang M.S.,Korea Institute of Machinery and Materials | Choi B.O.,Korea Institute of Machinery and Materials | Lee J.H.,KORAIL Research Institute
Transactions of the Korean Society of Mechanical Engineers, A | Year: 2014

Reliability allocation is generally used during the early stage of system development to apportion the system reliability target to its individual modules. This paper presents a comprehensive method for performing the reliability allocation of KTX door systems. Nine criteria for reliability allocation include failure criticality, operating time, risk, complexity, failure rate, maintenance, manufacturing technology, working condition, and reliability cost. For satisfying the system reliability target, the allocated B10 lives of four modules are provided. © 2014 The Korean Society of Mechanical Engineers. Source

Ha O.,KORAIL Research Institute | Park D.,University of Seoul | Lee K.,Yonsei University | Won J.,Hanyang University
KSCE Journal of Civil Engineering | Year: 2011

The objective of this study is to identify evaluation criteria for evaluating residential area road networks. To this end, existing studies regarding urban plan paradigms, neighborhood road network designs and road network evaluation criteria are reviewed, leading to the selection through first and second expert questionnaire surveys of 42 road network evaluation criteria. The road network evaluation criteria were divided into interregional road networks and regional road networks. To derive the evaluation criteria, the former were divided into motorways (main roads and auxiliary main roads) and public transportation, while the latter were divided into motorways (distributed roads, local roads), pedestrian ways and bicycle ways. Analytical Hierarchy Process (AHP) analysis of the weighted values of the evaluation criteria revealed the regional road networks to be more important than the interregional road networks, and the eco-friendly transportation networks such as pedestrian ways and bicycle ways to be more important than others. The road network evaluation criteria were divided into quantitative and qualitative indicators, and the methods for their scoring were presented by considering the characteristics of each evaluation criterion. Finally, the practicality of these evaluation criteria was investigated with a case study that examined a residential area redevelopment project of the "Jeonnong · dapshim-ri rearrangement promotion". In the evaluation of the road networks before and after implementation of the development project, the evaluation scores of the interregional road networks did not show any significant differences, while the evaluation scores of regional road networks did. This result indicated that the conditions of the regional road networks, including motorways (distributed roads, local roads), were considerably improved by the case region development project. © 2011 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg. Source

Ha O.-K.,KORAIL Research Institute | Song Y.-S.,Korea Institute of Construction Technology | Chung K.-Y.,Sangji University | Lee K.-D.,Yonsei University | Park D.,University of Seoul
Personal and Ubiquitous Computing | Year: 2014

The development of information technology has rapidly changed the logistics industry. RFID has become more and more important in the context of supply chain management (SCM), and implementation of RFID in SCM brings with it the potential to manage the information flow and to support communication and collaboration along the supply chain. This study was conducted to build a relation model, which is a structural model, to identify the effects of introducing RFID into the supply chain of the food and beverage industry in Korea. The supply chain of the food and beverage industry was divided into five activities: procurement, production, transport, sale, warehousing, and administration. This study was based on the premise that RFID will be embedded in a transport box or pallet circulated in the SC. The model showed that SC activities have positive relationships through the RFID system, and the introduction of RFID promotes information interchanges between SC activities, which in turn enable the coordination and consolidation of a total SCM. From the results of this study, it is expected that the RFID system does not only enable the SC partners to improve their utilities but also promotes the efficiency of SCM as a whole. This is meaningful considering that there is still a controversy regarding the effects of RFID on SCM. © 2013 The Author(s). Source

Park H.,University of Seoul | Park D.,University of Seoul | Kim C.,Korea Transport Institute | Kim H.,KORAIL Research Institute | Park M.,Inha University
Canadian Journal of Civil Engineering | Year: 2013

One of the major issues when applying truck destination choice models with a large number of alternatives is how to sample a set of non-chosen traffic analysis zones (TAZs) to construct a destination choice set. Despite the large number of studies applying various sampling strategies, the question remains as to what are optimal strategies in model development. This study examined how the sampling strategies affect the performances of truck destination choice models. Two sampling methods (simple random sampling and stratified importance sampling) and four different sample sizes were tested using the truck trip data of Korea. For stratified importance sampling, Moran's I statistics were used to divide the entire study area into multiple strata, and Neyman allocation was used to determine the appropriate number of samples for each stratum. The truck trip productions were distributed by a Monte Carlo simulation, and two measurements of effectiveness (MOEs), average trip length (ATL) and trip length distribution (TLD), were used to evaluate and compare the performance of the destination choice models with respect to the sampling strategy. The results showed that the models using stratified importance sampling with smaller sample sizes performed better than others. Source

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