• Title, Summary, Keyword: Railway vehicle

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Analytical Study of Railroad Bridge for Maglev Propulsion Train with Dynamical Influence Variable (동적영향변수를 통한 자기부상열차용 철도교의 해석적 연구)

  • Yoo, Yi-Seul;Park, Won-Chan;Yhim, Sung-Soon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.4
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    • pp.532-542
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    • 2018
  • Because maglev trains have a propulsion and absorption force without contact with the rails, they can drive safely at high-speed with little oscillation. Recently, test model of a maglev propulsion train was produced and operated, and has since been chosen as a national growth industry in South Korea; there have been many studies and considerable investment in these fields. This study examined the dynamic responses due to bridge-maglev train interaction and basic material to design bridges for maglev trains travelling at high-speed. Depending on the major factors affecting the dynamic effects, the scope of this study was restricted to the relationship between dynamic responses. A concrete box girder was chosen as a bridge model and injured train and rail types in domestic production were selected as the moving train load and guideway analysis model, respectively. From the analysis results, the natural frequency of a bridge for a maglev train, which has a deflection limit L/2000, was higher than those of bridges for general trains. The dynamic responses of the girder of the bridge for a maglev train showed a substantial increase in proportion to the velocities of the moving train like other general bridge cases. Maximum dynamic response of the girder is shown at a moving velocity of 240km/h and increased with increasing moving velocity of train. These results can be used to design a bridge for maglev propulsion trains and provide the basic data to confirm the validity and verification of the design code.

A Study on the Dynamic Behavior of the High Speed Railway Tracks (고속철도(高速鐵道)의 궤도(軌道)에 대한 동특성(動特性) 연구(研究))

  • Moon, Je Kil;Kang, Kee Dong
    • Journal of The Korean Society of Civil Engineers
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    • v.12 no.1
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    • pp.97-105
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    • 1992
  • The purpose of this study is to provide the cause and countermeasure for track problems in the high speed railways due to the irregularly increasing dynamic wheel loads running over the speed range of 300 km/h. It has long been recognised that the track problems encountered on high speed railways are associated mainly with vertical dynamic loads which are related to the unsprung mass of vehicles and track irregularities. In addition to these parameters for the estimation of the dynamic wheel load variation, however, the dynamic characteristics of track structures are discussed in this paper with reference to mathematical modelling of the tracks and vehicle. From the results of the more detailed analyses, the effects of track stiffness and damping characteristics are considered to be significant for reducing the dynamic wheel loads. To make this point clear and appraise the overall performance of the track components, the theoretical analysis on the dynamic behavior of the tracks and wheel set impact tests on several track structures are performed. The experimental results from different track components are compared with each other. The track stiffness and damping characteristics are also presented quantatively.

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Analysis of Vibration Characteristics for a Molded Dry-type Potential Transformer (몰드형 건식 계기용 변압기 진동 특성 분석)

  • Kim, Moosun;Jang, Dong Uk;Kim, Seung Mo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.3
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    • pp.209-214
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    • 2017
  • Most of the present potential transformers of train vehicles are of the oil-type filled with insulating oil and are susceptible to problems such as explosion due to the increase in the internal pressure during train operation and poor reliability near the end of their life cycle. As a solution to this problem, it is necessary to develop a molded dry-type potential transformer with excellent pressure-resistance performance using insulating resin. In order to localize the product, the Korea Railroad Research Institute has been developing a molded dry-type potential transformer. As part of this research, it is necessary to analyze the vibration characteristics of the developed product and to check the transformer performance in a vibration environment. In this study, a resonance test and simulated long-term life test of the developed product were conducted according to the KS R 9144 and IEC 61373 standards, respectively, which are vibration test methods for railway vehicle parts. Their natural frequencies were analyzed by comparing the results of the numerical modal analysis and resonance test, in order to confirm their adherence to the standards. Also, the performance test after the simulated long-term life test confirmed that the operation of the developed transformer was not problematic even in a long-time vibration environment.

Aerodynamic Characteristics of a Tube Train (튜브 트레인 공력특성 해석)

  • Kim, Tae-Kyung;Kim, Kyu-Hong;Kwon, Hyeok-Bin
    • Proceedings of the KSR Conference
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    • pp.139-150
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    • 2010
  • Recently, full-scale research about a passenger tube train system is being progressed as a next-generation transportation system in Korea in light of global green technology. The Korea Railroad Research Institute (KRRI) has commenced official research on the construction of a tube train system. In this paper, we studied various parameters of the tube train system such as the internal tube pressure, blockage ratio, and operating speed through computational analysis with a symmetric and elongated vehicle. This study was about the aerodynamic characteristics of a tube train that operated under standard atmospheric pressure (open field system, viz., ground) and in various internal tube environments (varying internal tube pressure, blockage ratio, and operating speed) with the same shape and operating speed. Under these conditions, the internal tube pressure was calculated when the energy efficiency had the same value as that of the open field train depending on various combinations of the operating speed and blockage ratio (the P-D relation). In addition, the dependence of the relation between the internal tube pressure and the blockage ratio (the P-${\beta}$ relation) was shown. Besides, the dependence of the relation between the total drag and the operating speed depending on various combinations of the blockage ratio and internal tube pressure (the D-V relation) was shown. Also, we compared the total (aerodynamic) drag of a train in the open field with the total drag of a train inside a tube. Then, we calculated the limit speed of the tube train, i.e., the maximum speed, for various internal tube pressures (the V-P relation) and the critical speed that leads to shock waves under various blockage ratios, which is related to the efficiency of the tube train (the critical V-${\beta}$ relation). Those results provide guidelines for the initial design and construction of a tube train system.

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Development of Train Velocity and Location Tracking Algorithm for a Constant Warning Time System (철도건널목 정시간 제어를 위한 열차속도 및 위치추적방식 개발)

  • Oh, Ju-Taek;Kim, Tae-Kwon;Park, Dong-Joo;Shin, Seong-Hoon
    • Journal of Korean Society of Transportation
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    • v.23 no.4
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    • pp.17-28
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    • 2005
  • About 91.1% of Railway-Highway Crossings (RHC) in Korea use a Constant Distance Warning System(CDWS), while about 8.9% use a Constant Warning Time System(CWTS). The CDWS does not recognize speed differences of approaching trains and provides only waiting times to vehicles and pedestrians based on the highest speed of approaching trains. Under the CDWS, therefore, low speed trains provide unnecessary waiting times at crossings which often generates complains to vehicle drivers and pedestrians and may cause wrong decisions to pass the crossings. The objective of this research is to improve the safety of the RHC by developing accurate a CWTS. In this research a train speed and location detection system was developed with ultra sonic detectors. Locations of the detectors was decided based on the highest speed and the minimum warning time of Saemaul of 160 km/h. To validate the algorithms of the newly developed systems the lab tests were conducted. The results show that the train detection system provides accurate locations of trains and the maximum error between real speeds of trains and those of the system was 0.07m/s.

Fatigue Analysis for Levitation Rail of Urban Maglev System (도시형 자기부상열차 부상레일의 피로해석)

  • Kim, Kyung-Taek;Kim, Jae-Yong;Kim, Yong-Hwan;Park, Jin-Soo;Pyen, Sang-Yun
    • Proceedings of the KSR Conference
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    • pp.39-45
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    • 2008
  • A levitation rail is placed on the top of track structure to operate Maglev vehicles and a part of track that link up with a sleeper is applied repeated load in Maglev vehicles operation. This paper aimed to verify validity of design for levitation rail, through the fatigue analysis about load which is applied to levitation rail in Maglev vehicles operation and impact load occurring in an emergency landing. Load conditions applied design load(23kN/m) in normal operation and skid drop load(24kN/m) in vehicle drop. And boundary conditions are consider bolt fixing and welding. Through static analysis, weak point and maximum stress of levitation rail could be obtained. S-N(stress-life) method was used in oder to predict fatigue life, and Goodman relationship was applied to consider a effect of mean stress. Also damage was calculated by using Miner's. As a result of fatigue analysis, levitation rail had a fatigue life which was more than requirement ($10^6$cycle) in all analysis conditions. Assumption that $10^8{\sim}10^9$cycles is infinite life, all analysis conditions had infinite life except a case under drop load and bolt fixing($1.21{\times}10^6$).

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Analysis for Roll Forming Process to Levitation Rail of Urban Maglev System (도시형 자기부상열차 부상레일의 롤 성형공정 해석)

  • Kim, Kyung-Taek;Kim, Jae-Yong;Kim, Yong-Hwan;Park, Jin-Soo;Pyen, Sang-Yun
    • Proceedings of the KSR Conference
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    • pp.31-38
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    • 2008
  • This Study discussed the roll forming process analysis of levitation rail for urban Maglev vehicle. To verify validity of roll forming process, we analyzed roll forming process for track shoe which is similar to levitation rail. The analysis process was composed of 12 passes and was performed for only 8 passes except overlapping passes. In the variation of temperature with each pass, surface temperature of the structure was cooled from initial $1200^{\circ}C$ to $1010^{\circ}C$ during 30 second before first pass, and central temperature and surface temperature was cooled to $980^{\circ}C$ and $900^{\circ}C$ in final pass, respectively. A length of structure after final pass is about 5 times longer than that before roll forming process. A strain of structure had a higher value in the inner part of the track shoe and show from minimum 2.5 to maximum 6.5. A torque applying on roll appear high in 2, 3 and 4 passes and a maximum value was $27,000ton{\cdot}mm$. Also it was analyzed that a load to the normal direction needs maximum 300ton.

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Solving Probability Constraint in Robust Optimization by Minimizing Percent Defective (불량률 최소화를 통한 강건 최적화의 확률제한조건 처리)

  • Lee, Kwang Ki;Park, Chan Kyoung;Kim, Geun Yeon;Lee, Kwon Hee;Han, Sang Wook;Han, Seung Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.8
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    • pp.975-981
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    • 2013
  • A robust optimization is only one of the ways to minimize the effects of variances in design variables on the objective functions at the preliminary design stage. To predict the variances and to formulate the probabilistic constraints are the most important procedures for the robust optimization formulation. Though several methods such as the process capability index and the six sigma technique were proposed for the prediction and formulation of the variances and probabilistic constraints, respectively, there are few attempts using a percent defective which has been widely applied in the quality control of the manufacturing process for probabilistic constraints. In this study, the robust optimization for a lower control arm of automobile vehicle was carried out, in which the design space showing the mean and variance sensitivity of weight and stress was explored before robust optimization for a lower control arm. The 2nd order Taylor expansion for calculating the standard deviation was used to improve the numerical accuracy for predicting the variances. Simplex algorithm which does not use the gradient information in optimization was used to convert constrained optimization into unconstrained one in robust optimization.

Development of Switching and Heating Devices in Embedded Rack Track for Environmental-friendly Mountain Railway (친환경 산악철도 매립형 궤도의 선로전환기 및 히팅장치 개발)

  • Seo, Sung-il
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.503-510
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    • 2020
  • Eco-friendly mountain railways operate on concrete rack tracks embedded on existing sharp curved and steep roads to preserve the environment in mountainous areas. Owing to the narrow roads, single lines are inevitable, and many branches are required. In branches, previous switchers and heating devices cannot be applied, because of the limited spacing for the rack and the slow removal of thick ice. To solve these problems, a switch and a heating device have been developed. The switcher changes the line by moving the block of concrete track with hydraulic actuators. The lack of discontinuity reduces the derailment risk and makes locking simple. The heating device uses high frequency induction coils to increase the efficiency and melt the thick ice rapidly. The prototype switcher and heating device were produced and operated to prove their performance. The heating device yielded a 10 times greater efficiency than the previous one. The switcher and heating device are the essential core technologies for the operation of mountain trams in winter and contribute to the spread of mountain railways to domestic or foreign resort areas by enhancing safety and efficiency. In addition, they can provide transportation rights to local residents in poor winter traffic, and bring about tourism and local economic growth.

A Dynamic Behavior Evaluation of the Curved Rail according to Lateral Spring Stiffness of Track System (궤도시스템의 횡탄성에 따른 곡선부 레일의 동적거동평가)

  • Kim, Bag-Jin;Choi, Jung-Youl;Chun, Dae-Sung;Eom, Mac;Kang, Yun-Suk;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.517-528
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    • 2007
  • Domestic or international existing researches regarding rail damage factors are focused on laying, vehicle conditions, driving speed and driving habits and overlook characteristics of track structure (elasticity, maintenance etc). Also in ballast track, as there is no special lateral spring stiffness of track also called as ballast lateral resistance in concrete track, generally, existing study shows concrete track has 2 time shorter life cycle for rail replacement than ballast track due to abrasion. As a result of domestic concrete track design and operation performance review, concrete track elasticity is lower than track elasticity of ballast track resulting higher damage on rail and tracks. Generally, concrete track has advantage in track elasticity adjustment than ballast track and in case of Europe, in concrete track design, it is recommended to have same or higher performance range of vertical elastic stiffness of ballast track but domestically or internationally review on lateral spring stiffness of track is very minimal. Therefore, through analysis of service line track on site measurement and analysis on performance of maintenance, in this research, dynamic characteristic behaviors of commonly used ballast and concrete track are studied to infer elasticity of service line track and experimentally prove effects of track lateral spring stiffness that influence curved rail damage as well as correlation between track elasticity by track system and rail damage to propose importance of appropriate elastic stiffness level for concrete and ballast track.

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