• Proceedings of the KSR Conference
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• 2009.05a
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• pp.529-538
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• 2009

A trial run of locally-developed tilting train has been in process on Chungbuk line since the test vehicle was first produced. For the system stabilization, interface verification among the systems including track, structure, catenary and signaling system, not to mention the rolling stock, is very crucial. Therefore, in this study, the dynamic rail force of the tilting (Hanvit 200), high-speed (KTX) and general (Mugunghwa) vehicle caused by driving in transition curve track was measured. And, it compared the tilting response with the other by using the measured wheel load data in transition curve track, and then evaluated probability the range of wheel load fluctuation for the variable dynamic vertical and lateral wheel load. As a result, a range of wheel load by occured a change of cant from the high-speed and general vehicle which had fixed bogie structure was distributed throughout small deviation (${\Delta}8{\sim}13kN$). Otherwise, in case of the tilting train which was consisted of the pendulum bogie structure was distributed wide range about large deviation (${\Delta}25{\sim}28kN$) by changed of cant.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.230-237
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• 2000

The wheel bearing in vehicles has been improved to unit module by joining a bearing to a hub in order to achieve weight reduction and easy assembly. Currently, the contact force between a raceway and balls of a bearing is applied as the external force in order to analyse the structure of the unit type bearings. In this paper, simplified boundary conditions are discussed for structure analysis of wheel bearing unit. From the procedure, the contact conditions of balls and race in wheel bearing unit are considered as equivalent non-linear spring elements. The end node of a spring element is constrained in displacement. And the external force of boundary conditions is applied at the contact point between tire and road. For the evaluation of this analysis, its results for the force of spring elements are compared with contact forces of calculated results. and also maximum equivalent stresses of analysis are compared with results of test at the flange of inner ring. The analysis results with proposed boundary conditions are more accurate than results from analysis which is generally used.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.29-34
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• 2010

The main objective of this research is to present the behaviors of precast concrete slab under moving wheel loads. The simulated moving wheel tester and precast concrete slab were designed for this research. In particular, a comparative analysis between the structural analysis and the moving wheel load test was evaluated in connection parts, deformation, bedding layer of concrete slab panels. In the comparisons of the test results from static and moving wheel loads, the maximum deformations were similar. It should be noted that the deformation of panel 2 from the static loading test was larger than that of other panels, while the deformations of panels 1 and 3 were more noticeable than that of panel 2.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1042-1047
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• 2004

Urethane is a high polymeric and elastic material useful in designing mechanic parts that cannot be molded in rubber or plastic material. Especially, urethane is high in mechanical strength and anti-abrasive. Hereby, an urethane coated aluminum wheel is used for supporting of OHT vehicle moving back and forth to transport products. For the sake of verifying the safety of the vehicle, structural safety for applied maximum dynamic load on a urethane wheel needs to be carefully examined while driving. Therefore, we have performed the dynamic simulation on the OHT vehicle model. Although the area definition of applied load can be obtained from the previous study of Hertzian and Non-Hertzian contact force model when having exact properties of contact material, static analysis is simulated, since the proper material properties of urethane have not been guaranteed, after we have performed the actual contact area test for each load. In case of this study, the method of distributing load for each node is included. Finally, in comparison with result of analysis and load-displacement curve obtained from the compression test, we have defined the material properties of urethane. In the analysis, we have verified the safety of the wheel. After all, we have performed a mode analysis using the obtained material properties. With the result, we have the reliable finite element model.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.114-120
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• 2005

Urethane is a high polymeric and elastic material useful in designing mechanic parts that cannot be molded with rubber or plastic material. In particular, urethane is high in mechanical strength and anti-abrasive. Hereby, a urethane coated aluminum wheel is used to support of the OHT vehicle moving back and forth to transport products. For the sake of verifying the safety of the vehicle, structural safety fur applied maximum dynamic load on a urethane wheel must be examined carefully while driving. Therefore, we performed a dynamic simulation on the OHT vehicle model and we determined the driving load. The area definition of applied load may be obtained from the previous study of Hertzian and Non-Hertzian contact force model having exact properties of contact material. But the static analysis is simulated after we have performed the actual contact area test for each load since the proper material properties of urethane have not been guaranteed. In this study, the method of distributing loads for each node is included. Finally, in coMParison with the results of analysis and load-displacement curve obtained from the compression test, we have defined the material properties of urethane. In the analysis, we verified the safety of the wheel. Finally, we performed a mode analysis using the obtained material properties. With these results, we presented a reliable finite element model.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.535-544
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• 2011

The rail surface defects can cause the high impact load on the track and lead to the progress of the rail fatigue damage and the rail break. In case of the rail break, there is a great deal of risk for derailment, and thus the maintenance criteria for the rail surface defects are of great importance. In this study, using the dynamic train-track interaction analysis program, the impact wheel loads and rail bending stresses according to the depths of the surface defects have been calculated with the input data of the rail surface irregularities measured at 43 spots with surface defects in the ballasted track of high-speed railway. Considering the irregularity of track geometry, the allowable limits of wheel load and rail bending stress have been set, and the maintenance criteria for the rail surface defects was suggested by analyzing the relationship of the maximum values of wheel load and rail bending stress versus depth and width of rail surface defect. The analysis results suggest that the allowable depth of the surface defect is determined approximately 0.2mm from the limit of the impact wheel load.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.303-306
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• 2005

For checking influence of load-position and system of stress-transmission in precast concrete bridge deck system, the test composite bridge was made a experiment by the wheel load machine. The result of experiment was the loop joint system of the precast decks has a difference which was the transmission system of longitudinal stress, comparing with general RC bridge deck system. The loop joint system has a behavior independently.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.8
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• pp.459-466
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• 2000

In this paper, we propose an attitude controller for an unstructured object using CMG(Control Moment of Gyro) subsystem, which has a stabilizer function. The CMG subsystem consists of one motor for spinning the wheel and the other motor for turning the outer gimbal. While the wheel of CMG subsystem is spinning at high speed, applying force to the spin axis of the wheel leads the torque about the vertical axis. We utilize the torque to control the attitude of object in this study. For the stabilizer function, in additiion, holding the load at the current position, the power applied to the gimbal motor of CMG will be cut, which result in the braking force to stop the load by gyro effect. However, due to the gear reduction connected to outer gimbal, slow load motion cannot generate the braking force. Thus, in this study, we are willing to make a holding force by applying control power to the gimbal motor from the signal of piezoelectric gyroscopic sensor that detected the angular velocity of the load. These two features are demonstrated in experiment, carrying a beam with crane. As a result, load was started to rotate by controlling gimbal positiion and was stopped by turning off the gimbal power. Moreover, slow movement of the load was also rejected by additional control with gyroscopic sensor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1391-1398
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• 2004

Railway wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles became more severe in recent years due to the increase of speed. Therefore, a more precise evaluation of wheelset life and safety has been requested. Wheel/rail contact fatigue and thermal cracks due to braking heat are two main mechanisms of the railway wheel failure. In this paper, an evaluation procedure for the contact fatigue life of railway wheel is proposed. One of the main sources of the contact zone failure is the residual stress. The residual stress on wheel is formed during the manufacturing process which includes a heat treatment, and then is changed by contact stress developed by wheel/rail contact and thermal stress induced by braking. Also, the cyclic stress history for fatigue analysis is determined by applying finite elements analysis for the moving contact load. The objective of this paper is to estimate fatigue life by considering residual stress due to heat treatment, braking and repeated contact load, respectively.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.365-373
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• 2011

In general, when train drives boost and traction mode, force of delivering to the track was difference between boost and traction driving mode. But, in korea, we've never performed that measure the track wheel load and lateral force while boost and traction driving. This study measured wheel load and lateral force using combination of 7200type locomotive and six freight car. And the train used single and automatic brake. The train drives boost and traction mode. In order to the difference radius of curve, we had measured at 3 point in the curve of turnout.