• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.493-500
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• 2017

Based on the data accumulated through EMU fault management, this paper examines the reliability of old railway car parts and proposes measurements to improve safety. Subway Line 7 of the Seoul Metropolitan Rapid Transit Corporation, auxiliary power unit (Static Inverter) of the EMU second version is a core equipment to supply power to various room-service units in cars and make an effect directly on passenger satisfaction. To analyze the pattern of failure throughout the field data over a long period of time, this analysis of statistics and reliability considers the operating environment and stress factors. This statistical analysis presents the correlation between failure and the temperature stress factors related to frequent failure occurring intensively in summer. In addition, throughout the analysis of the life of the IGBT inverter, the effect of the temperature stress factor was observed before and after the repair. As a result of an analysis of the optimal operating conditions considering two variations of EMU, such as variable load and outside temperature, a difference in the cooling capacity between the optimal operating conditions and frequent failure conditions was observed. Based on this analysis, this paper suggests a way to minimize cooling capacity difference for the optimal operational conditions.

• Journal of the Korean GEO-environmental Society
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• v.15 no.11
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• pp.67-75
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• 2014

In this study, the staged seismic performance evaluations were conducted to the 91 high speed railway tunnels in use for checking whether to comply with the recent design criteria or not. In addition, the seismic fragility functions of the tunnels were developed to allow the probabilistic risk assessment. The results of the staged seismic performance evaluations which consist of a preliminary assessment and a detailed assessment, show that the tunnels comply with the recent design criteria. With reference to the results of previous studies, a form of the proposed seismic fragility functions was set as a log-normal distribution by PGA, and the parameters of the functions were determined by using the probability of damage for the design PGA level. The seismic fragility functions were developed for each types (Cut & Cover, NATM) of tunnels. The seismic fragility functions from this study and the existing research results (FEMA, 2004) were compared to evaluate the seismic performance level of the tunnels, as a result the tunnels of this study were relatively superior to the ASSM tunnels on the seismic performance.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.262-270
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• 2011

Track support stiffness which affected track maintenance and riding comfort had a big effect on the track and train. Also, track support stiffness of the track design which was based on theory differs from track support stiffness of the track generated on the field. Track support stiffness was generated by several factors such as dynamic wheel loads, vertical displacement of track, and stress at rail bottom on the field test. With the results of the field test was compared with theoretical value. This paper analyzed that track support stiffness of ballast depended on condition of ballast, and support stiffness of concrete track also depended on the characteristic of track structures such as, normal elastic fastening system, rail floating system and sleeper floating system. However, on the ballast and concrete track, the designed track support stiffness was underestimated less than the measured track support stiffness. When the track condition was estimated on service line, it would not consider the track condition on the field. Therefore, this study proposed the various track type and the range of track support stiffness based on the experimental test.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.443-452
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• 2011

This study analyzed passenger travel patterns especially for the transfer from metro to bus by using transit smart card data. We classified three types of land use such as residential, business, and shopping area where metro stations are located. The results show that more number of transfers was observed at residential area compared to that of shopping and business area. Also, more number of transfers from metro to arterial bus was observed than that of transfers to local bus. Further, the high number of transfers to arterial bus was observed at business and shopping area. This means that the transfer to bus at metro stations varies by land use. The egress walk distance from metro station was found to be approximately 400 meters and the average walk distance of young people was found to be shorter than that of the old.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.25-35
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• 2008

The ridership and transit systems are influenced by the expansion of metro-rail in Seoul metropolitan area. However, it has been difficult to measure its precise quantitative influences. Also effective policy implementations have been limited due to the lack of practical evidences. Thus an empirical analysis for an operating metro-rail is essentially required. In this regard, this study examines the impact of the Jungang line on transportation system, whose metro-rail block has been recently started new service. The main interest of this study is to find out the changes of ridership and to forecast the ridership changes by the metro-rail service. The results indicate that the effect on auto users is less than that of bus users. The auto demand is decreased by 33.3% and the bus demand by 66.6%. Additionally, its influence on Gyeonggi-do bus was greater compared with that on the Seoul bus. From questionnaire survey, this results could be confirmed. To sum up, the metro-rail gives less influences on auto users, while it gives greater influences on bus users.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.689-696
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• 2001

Large-scale Multi-disciplinary Systems(LMS) such as transportation, aerospace, defense etc. are complex systems in which there are many subsystems, interfaces, functions and demanding performance requirements. Because many contractors participate in the development, it is necessary to apply methods of sharing common objectives and communicating design status effectively among all of the stakeholders. The processes and methods of systems engineering which includes system requirement analysis; functional analysis; architecting; system analysis; interface control; and system specification development provide a success-oriented disciplined approach to the project. This paper shows not only the methodology and the results of model-based systems engineering to Automated Guided Transit(AGT) system as one of LMS systems, but also propose the extension of the model-based tool to help manage a project by linking WBS (Work Breakdown Structure), work organization, and PBS (Product Breakdown Structure). In performing the model-based functional analysis, the focus was on the operation concept of an example rail system at the top-level and the propulsion/braking function, a key function of the modern automated rail system. The model-based behavior analysis approach that applies a discrete-event simulation method facilitates the system functional definition and the test and verification activities. The first application of computer-aided tool, RDD-100, in the railway industry demonstrates the capability to model product design knowledge and decisions concerning key issues such as the rationale for architecting the top-level system. The model-based product design knowledge will be essential in integrating the follow-on life-cycle phase activities. production through operation and support, over the life of the AGT system. Additionally, when a new generation train system is required, the reuse of the model-based database can increase the system design productivity and effectiveness significantly.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.776-781
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• 2005

In this paper, using received channel information, we analyze performance in MIMO multiuser system in low-to-medium mobile speed by selecting each user's constellations, powers, and transmit antennas. Given a target of symbol error, we determine each user's constellations, powers, selected tranprobability smit antennas such that the required signal-to-noise(SNR) is minimized for MMSE, V-BLAST receiver according to each user's information and channel estimation information. When we do power control with antenna selection technique through uplink channels of MIMO system in low-to-medium mobile speed, we analyze system performance with wireless channel information from Base-Station(BS) to Users. By simulation, it has been shown that the proposed antenna selection scheme for transmitting data offer better performance improvement than all transmit antennas for transmitting data.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.639-645
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• 2015

Recently, a study on the commercialization of Rope type Platform Safe Door (RPSD) technology has commenced. The study focuses on RPSD, in which a rope screen ascends to allow safe passage from the platform to the transit vehicle in aboveground stations. Currently, a pilot installation has taken in place with Daegu Metro Line 2 in MoonYang station starting from March of 2013. However, there is a need to select an appropriate pilot installation's object for the improvement in the future RPSD. An appropriate designation would correspond with the needs of the railroad corporation and as a historic railway platform with safe facilities. This study tried to usa Analytic Hierarchy Process (AHP) to determine the priority of the KTX stations to attain a list of appropriate designations for future RPSD installations by analyzing the followings: management of the facilities, operational risks, and intent of business projects. As a case study, it was applied to the evaluation of the KTX stations. For the application, it used relative measurement to calculate the weight of upper level structuring, and absolute measurement for low level structuring instead of pairwise comparisons.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1828-1838
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• 2009

This study will analyze what is favorable of urban structure in order to introduce new transit system like bi-modal tram. As a reasonable transport mode in a city, the bi-modal tram needs to be considered with respect to the space structural pattern and city growth process. The result of this study may provide the basic resource that helps transport decision makers to decide how to introduce bi-modal tram by considering the urban structural characteristics. Also, the results that analyzed a functional characteristic of a bi-modal tram with a effective urban polices will be informative for practical use.