• Title, Summary, Keyword: Rail Stability

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Unsteady Aerodynamic Loads on High Speed Trains Passing by Each Other

  • Hwang, Jae-Ho;Lee, Dong-Ho
    • Journal of Mechanical Science and Technology
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    • v.14 no.8
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    • pp.867-878
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    • 2000
  • In order to study unsteady aerodynamic loads on high speed trains passing by each other 350km/h, three-dimensional flow fields around trains during the crossing event are numerically simulated using three-dimensional Euler equations. Roe's FDS with MUSCL interpolation is employed to simulate wave phenomena. An efficient moving grid system based on domain decomposition techniques is developed to analyze the unsteady flow field induced by the restricted motion of a train on a rail. Numerical simulations of the trains passing by on the double-track are carried out to study the effect of the train nose-shape, length and the existence of a tunnel on the crossing event. Unsteady aerodynamic loads-a side force and a drag force-acting on the train during the crossing are numerically predicted and analyzed. The side force mainly depends on the nose-shape, and the drag force depends on tunnel existence. Also. a push-pull (i.e.impluse force) force successively acts on each car and acts in different directions between the neighborhood cars. The maximum change of the impulsive force reaches about 3 tons. These aerodynamic force data are absolutely necessary to evaluate the stability of high speed multi-car trains. The results also indicate the effectiveness of the present numerical method for simulating the unsteady flow fields induced by bodies in relative motion.

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An Experimental Study on the Transient Behavior of Vehicle Rollover (차량 롤전복의 과도거동에 관한 시험적 연구)

  • Lee, Myung-Su;Kim, Sang-Sup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.3
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    • pp.113-121
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    • 2011
  • Rollover accident is one of the serious traffic accident and rollover accident takes high portion of all accident. The most common type of rollover is a tripped rollover which occupy 95% of all type of single-vehicle rollover. Tripped rollover occurs when a vehicle leaves normal road way and tripped by loose gravel, soil of fixed object such as guard rail, curbs and ditches. And the rest of the type of rollover is un-tripped rollover. An un-tripped rollovers that occurs during high-speed collision avoidance maneuvers. In this paper, presents the explanation of the un-tripped rollover test method and procedure, additionally this paper deals with various occurrence in the un-tripped test such as occurring excessive tire camber in the un-tripped test, tire side-wall contact with road surface and roll oscillation. And this paper analyzes the analysis of the roll rate amplitude in specific frequency through the FFT (Fast Fourier Transform) and the roll angle at the steering reverse timing which is the Fishhook test roll rate feedback time. Finally, this paper analyzes the relations between the estimated steady state roll gain and rollover stability.

Effect of Injection Strategy on the Exhaust Emission and Performance Characteristics of a Light-duty Diesel Engine (승용 디젤 엔진에서 분사 전략이 배출 가스 및 엔진 성능에 미치는 영향에 관한 연구)

  • Roh, Hyun-Gu;Lee, Doo-Jin;Lee, Chang-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.3
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    • pp.99-105
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    • 2011
  • This paper described the effect of the multiple injections on the emission characteristics and combustion stability in a common rail diesel engine. In order to investigate the influence of multiple injections in a passenger car diesel engine, the injection strategy was varied with pilot injection, post injection and one main injection at various conditions. Based on the experimental results, the combustion and emissions characteristics were analyzed for the various injection strategies such as main, pilot-main, double-pilot-main, double- pilot-main-post injection strategy. It is revealed that the $NO_X$, HC and CO emissions are reduced by double pilot and post injection at medium load, however, soot emission is increased. Also, in the case of multiple injection, the combustion pressure is increased smoothly near the TDC and the coefficient of variation and fuel consumptions are decreased.

Study of the effect of cleaning the intake manifold on common rail diesel engine and exhaust gases (커먼레일 디젤엔진의 흡기 매니폴더 클리닝이 배기가스에 미치는 영향에 관한 연구)

  • Kim, Tae-Jung;Hong, Sung-In
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.10
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    • pp.5912-5918
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    • 2014
  • Owing to highly developed industries and the use of fossil fuels, environmental problems becoming becoming pressing issues globally. Therefore, a study of automobile exhaust is urgently needed. Generally, air is sucked into the engine through the intake manifold. The aims of this study were to reduce the exhaust from used cars and increase the output by removing carbon deposits, which are considered a reason for the increasing exhaust and reduction of output, and the reduction of exhaust, variation of output and stability of idle speed were analyzed. The formation of carbon deposits within the suction manifold was investigated through a test device (KD147). In the intake manifold, the exhaust cleaning effect was confirmed.

An Automated Machining System for Steel Flat Bar Plasma Cutting in the Small Sized Shipbuilding Industry (중소조선용 철의장 가공자동화시스템 개발)

  • Ryu, Gab-Sang;Lee, Won-Hoo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.2
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    • pp.852-857
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    • 2011
  • The shipbuilding industry needs automation and mechanization to solve reduction of skilled workers and labor shortage. Ship manufacturing process is the lack of automation than standardized manufacturing field. In this paper, we design and development an process automation system for hand rail production. Mechanical parts of the cutting process was designed with efficiency, productivity and reliability, CATIA and ANSYS, the stability of the mechanical structure was confirmed. System control using a PCNC controller to provide an open and scalable, and operate using touch-screen display control and monitoring of the system was performed. The automatic system successfully passed the driving test and processing test, and it showed an excellent performance.

Lateral Vibration Analysis for Design Parameter of the Scale Model of a Railway Vehicle (축소형 철도차량의 설계변수에 따른 횡진동 해석)

  • Lee, Seung-Il;Choi, Yeon-Sun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.12
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    • pp.1231-1237
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    • 2006
  • The vibration of a running railway vehicle can be classified on lateral, longitudinal and vertical motions. The important factor on the stability and ride quality of a railway vehicle is the lateral motion. The contact between wheel and rail with conicity influences strongly on the lateral motion. In this study, an experiment for the vibration of a running railway vehicle was performed using a of the scale model of a railway vehicle. Also, the effects on the car-body, bogie and wheelset were examined for the weight and the stiffness of the second suspension system. The experimental results showed that the lateral vibration increases as the wheel conicity and stiffness of the second suspension system increase. And the lateral vibration of the bogie increases as the mass ratio between car-body and bogie increases. Also, the lateral vibration of the wheel becomes high at low speed, while the wheel of 1/20 conicity makes severe vibration at high speed running.

Dynamic Responses Characteristics of Steel Box Railway Bridges Subjected to Train Loading (열차주행에 따른 강박스 철도교의 동적응답특성)

  • Park, Sun-Joon;Kang, Sung-Hoo;Jo, Eun-Pyung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.12
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    • pp.1306-1314
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    • 2009
  • By rising the interests of the railroad, It has been required the research about railroad structure. And since 2000, the study about railway bridges caused by steel box railway bridges has been only 0.2 %. So I was hard to find out about steel box railway bridges. In this study, I evaluate and analyze 4 types(KTX, Saemaeul, Mugunghwa, Freight) of dynamic caused by train loading, natural frequency and damping ratio, verticality deflection and verticality acceleration, end slope deflection, impact factor for dynamic characteristics analysis. natural frequency was measured 2.45 Hz~3.34 Hz and damping ratio revealed for 1.26~2.84 %. Maximum verticality deflection(4.86 mm) was sufficiently satisfied the design criteria(30.1 mm), but in the case of verticality acceleration's respond, design criteria BRDM(bridge design manual) & CTRL presentation derive rail limit value 0.35 g be more than value 6 time recorded, maximum was measured 0.49 g in 3 kinds of train(KTX, Saemaeul, Mugunghwa), except for Freight. Survey impact factor of Experiment bridge was 0.20 which is measured when the KTX(15:04) was driving. impact factor is enough contended with design criteria 0.29 which is presented in domestic railway design criteria and thoroughly guarantee the dynamic stability.

Seismic Design of Steel Frame Model Considering the Panel Zone and Viscous Dampers (패널존과 점성감쇠기를 고려한 강골조 구조물의 내진 설계 모델)

  • Park, Sun-Eung;Lee, Tack-Woo
    • Journal of Korean Association for Spatial Structures
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    • v.20 no.2
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    • pp.87-94
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    • 2020
  • The present study is aimed to calculate the optimal damping according to the seismic load on the structure with a non-seismic design to perform structure analysis considering the deformation of structural joint connection and panel zone; to develop design program equipped with structural stability of the steel frame structures reinforced with the panel zone and viscous dampers, using the results of the analysis, in order to systematically integrate the seismic reinforcement of the non-seismic structures and the analysis and design of steel frame structures. The study results are as follows: When considering the deformation of the panel zone, the deformation has been reduced up to thickness of the panel double plate below twice the flange thickness, which indicates the effect of the double plate thickness on the panel zone, but the deformation showed uniform convergence when the ration is more than twice. The SMRPF system that was applied to this study determines the damping force and displacement by considering the panel zone to the joint connection and calculating the shear each floor for the seismic load at the same time. The result indicates that the competence of the damper is predictable that can secure seismic performance for the structures with non-seismic design without changing the cross-section of the members.

Investigation of the Bond and Deformation Characteristics between an Asphalt layer and a Concrete Slab used as the Trackbed Foundation of an Embedded Rail System for Wireless Trams (무가선 트램용 매립형궤도 아스팔트 포장층의 부착특성 및 변형발생특성 분석)

  • Cho, Hojin;Kang, Yunsuk;Lee, Suhyung;Park, Jeabeom;Lim, Yujin
    • Journal of the Korean Society for Railway
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    • v.19 no.2
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    • pp.224-233
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    • 2016
  • Embedded Railway Systems (ERS) will be adapted for wireless trams and will be constructed along city roadways. An asphalt layer should be overlaid on top of the concrete slab used as the trackbed structure in order to ensure smoothness and surface levels equal to those of existing road pavement in downtown city areas. However, the characteristics of an asphalt layer when used as overlay pavement for an ERS are complicated and the behavior of this material is not yet well defined and understood. Therefore, in this study, laboratory shear and tensile bond strength tests were conducted to investigate the bonding behavior of an asphalt layer in a multilayered trackbed section of an ERS. For the laboratory tests, a waterproof coating material was selected as a bonding material between the asphalt overlay and a concrete specimen. Valuable design parameters could be obtained based on the tensile and shear bond strength test results, providing information about the serviceability and durability of the overlaid pavements to be constructed alongside the ERS for wireless trams. In addition, a deformation analysis to assess the tensile strain generated due to truck axle loads at the interface between the asphalt layer and the concrete slab was conducted to verify the stability and performance of the asphalt layer.

Development of High Strength Lattice Girder and Evaluation of Its Performance (고강도 격자지보재의 개발 및 그 성능 평가)

  • Lee, Jae-Won;Min, Kyong-Nam;Jeong, Ji-Wook;Roh, Byoung-Kuk;Lee, Sang-Jin;Ahn, Tae-Bong;Kang, Seong-Seung
    • The Journal of Engineering Geology
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    • v.30 no.1
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    • pp.43-57
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    • 2020
  • The objective of this study was to evaluate the performance of high-strength lattice girders as a possible superior alternative to conventional steel arch ribs. For this purpose, the structural characteristics of supports were analyzed using numerical analysis, and their performance was evaluated using maximum bending load tests and tensile tests of the welded joint. According to the results of structural analysis, the optimum size of the upper and lower members and plates is 50 mm × 31.8 mm × 25.4 mm, demonstrating excellent functionality and economic efficiency. High-strength lattice girders of dimensions 55 mm × 30 mm × 20 mm and 85 mm × 30 mm × 20 mm, determined from bending load tests, are found to meet both the reference values and the target values of H-profiles 100 and 125. A review of the ratio of theoretical deflection to actual deflection shows that the high-strength lattice girder developed during this study meets fewer than five of the evaluation criteria for lattice girder deflections proposed by the Federal Railway Department of Germany. Finally, tensile test results reveal that the welded joint of the high-strength lattice girder at the main steel bar-auxiliary steel bar-plate junction exceeds the target value, indicating that the welded joint has sufficient stability.