• Proceedings of the KSR Conference
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• 1998.05a
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• pp.556-563
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• 1998

Railway bridges have a significant effect on the stress and displacement of continuous welded rail(CWR). Longitudinal compression force at high temperature, combined breaking or acceleration forces can introduce track buckling. On the other hand, longitudinal tensile forces, associated with low temperatures, in combination with breaking forces may break rail. Therefore, it is very important to work out thorough counter measures for those problems, specially in high speed rail which high safety is required. The exact evaluation of longitudinal force of rail has the key to the solution. The main aim of the present paper is to examine whether the longitudinal force of CWR's on Kyung-Bu-HSR satisfy the criteria to be fulfilled in the design of railway bridge. The analyses are carried out by using "CWRAP" program which was developed by our research group. The ballast resistance and breaking force effects on the longitudinal force of CWR are investigated.

• Wind and Structures
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• v.38 no.4
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• pp.325-339
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• 2024

The longitudinal force resulting from tornado loads on transmission line is considered a crucial factor contributing to the failure of transmission line structures during tornado events. Accurate estimation of this longitudinal force poses a challenge for structural designers. Therefore, the objective of this paper is to provide a set of charts that can be easily used to estimate the peak longitudinal forces transferred from the conductors to a tower. The critical wind field and corresponding configuration considered in this paper are previously studied and determined. The charts should account for all the conductor parameters that can affect the value of the longitudinal force. In order to achieve that, a parametric study is first conducted to assess the variation of the longitudinal forces with different conductor parameters, based on the critical tornado configuration. Results of this parametric study are used to develop the charts that can be used to calculate longitudinal forces by adopting a multi-variable line regression. The forces calculated from charts are validated by finite element analysis. An example for the usage of the charts is provided at the end of this paper.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.99-105
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• 2009

This research presents the method to decide proper locations for destressing of CWR using a non-destructive equipments to measure the longitudinal force(installation temperature) in CWR. The effect and necessity of destressing were analyzed by estimating changes of longitudinal force. The installation temperature was measured to find changes of longitudinal force in high speed and conventional lines before and after destressing or track maintenance at the locations where destressing was planed or where change of longitudinal force was expected during track maintenance. Past destressing was carried out within qualitative decision criteria. This research proposes the quantitative criteria to decide the priority order of the destressing locations reasonably by considering the difference of air temperature and stress free temperature during the track maintenances, the grade of ballast resistance force recovering and the length of destressing, etc.

• Transactions of the Korean Society of Mechanical Engineers
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• v.2 no.3
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• pp.62-68
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• 1978

The influences of the large amplitude free vibrations of simply supported Timoshenko beams with ends restrained to remain a fixed distance apart and with no axial restraints, which cause a longitudinal elastic force and a longitudinal inertia force, respectively, are investigated. The equations of motion derived by an appropriate linearizarion of the nonlinear strain- displacement relation have nonlinear terms arising from large curvature, longitudinal elastic force and longitudinal inertia force. The fourth order nonlinear partial differential equations for the deflection, can be reduced to the nonlinear ordinary differential equations by means of Galerkin procedure and a modal expansion. The general response and frequensy-amplitude relations are derived by the perturbation method of strained parameters. Comparison with previously published results is made.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.385-390
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• 2003

Recently, use of Continuous Welded rail(CWR) is increased for structural, economical reason but new problem is caused accordingly and phenomenon that give threat in traveling by ship stability of train is led. According as rail is prolonged, excessive relative displacement and longitudinal force can happen to rail by temperature change and external force. Specially, buckling or fracture of rail can happen in railroad bridges because relative displacement by bridge and properties of matter difference between rail grows and additional axial force happens to rail by behavior of bridge. According to several study, longitudinal force of rail in bridge is influenced with ballast resistance, elongation length, boundary condition, stiffness of framework. Non-linear behavior of ballast acts by the most important factor in interaction between rail and bridge. Therefore, must consider stiffness of bridge construction with non-linear characteristic of ballast and stiffness of base for accuracy with longitudinal force calculation and analyze. In this study, perform material non-linear analysis for longitudinal force of CWR and three dimensional buckling analysis to decide buckling force.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.443-450
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• 2014

In this study, we have discussed about the effect of hydrofoil arrangement and longitudinal moment characteristic on longitudinal motion stability of fully-submerged hydrofoil by the experiment of tandem hydrofoil model. First of all, tandem hydrofoil model that has canard wing arrangement has been made and characteristics of lift force and drag force by performing the lift force and drag force measuring experiment has also been estimated. Besides, tandem hydrofoil model's wing arrangement which has the initial stability and self stability of longitudinal motion has also been determined. In longitudinal stability experiment of tandem hydrofoil model, the motion characteristic of pitch and heave and the longitudinal stability of foil borne condition by variation of self stability of longitudinal moment and longitudinal distance are estimated. The result from the experiment and it's important conclusion can be described as below; Increase the self stability for longitudinal moment, the higher self stability for pitch motions in a constant pitch angles. By increasing the self stability for longitudinal moment, the range of fluctuation of pitch motion and heave motion for pitch angle also will change relatively small and longitudinal stability is excellent. Lastly, when the lift force of hydrofoil is remain constants, we can conclude that securing the enough self stability for longitudinal moment is essential for stable foil borne condition of tandem hydrofoil.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.512-519
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• 2016

In this study, the tire road friction estimation(TRFE) algorithm for controlling the rear wheel driving force of a 4WD vehicle during acceleration is developed using a standard sensor in an ordinary 4WD passenger car and a speed sensor. The algorithm is constructed for the wheel shaft torque, longitudinal tire force, vertical tire force and maximum tire road friction estimation. The estimation results of shaft torque and tire force were validated using a torque sensor and wheel force transducer. In the algorithm, the current road friction is defined as the proportion calculated between longitudinal and vertical tire force. Slip slop methods using current road friction and slip ratio are applied to estimate the road friction coefficient. Based on this study's results, the traction performance, fuel consumption and drive shaft strength performance of a 4WD vehicle are improved by applying the tire road friction estimation algorithm.

• Journal of Welding and Joining
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• v.34 no.6
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• pp.20-27
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• 2016

This study deals with the proper conditions of the trail rolling method (TRM) for the prevention of the buckling welding distortion at the AA5083 GMA butt weldment. For it, the effect of the working conditions of TRM including the rolling depth and the rolling distance between the welding torch and the roller on the longitudinal welding shrinkage force of the weldment was evaluated by using 3 dimensional thermo-mechanical FE analyses. The longitudinal welding shrinkage force inducing the buckling welding distortion at the GMA butt weldment was mitigated with an increase in the rolling depth and the rolling distance between the welding torch and the roller. Based on the results, the proper conditions of trail rolling method were established to reduce the longitudinal welding shrinkage force of the GMA butt weldment to below the critical value corresponding to the bucking distortion.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.7
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• pp.632-638
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• 2010

This paper presents an optimum tire force distribution method for 6WD/6WS(6-Wheel-Drive and 6-Wheel-Steering) electric vehicles. Using an independent steering and driving system, the performance of 6WD/6WS vehicles can be improved, as, for example, with respect to their maneuverability under low speed and their stability at high speed. Therefore, there should be a control strategy for finding the optimum tire forces that satisfy the driver's command and minimize energy consumption. From the driver's commands (steering angle and accelerator/brake pedal stroke), the desired yaw moment, the desired lateral force, and the desired longitudinal force were obtained. These three values were distributed to each wheel as the torque and the steering angle, based on the optimum tire force distribution method. The optimum tire force distribution method finds the longitudinal/lateral tire forces of each wheel that minimize the cost function, which is the sum of the normalized tire forces. Next, the longitudinal/lateral tire forces of each wheel are converted into the reference torque inputs and the steering wheel angle inputs. The proposed method was tested through a simulation, and its effectiveness was verified.

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.501-506
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• 2006