• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.660-663
• /
• 2008

In this study, it was mainly focused on the mechanism and reliability performances of PI/PET composites after many times of curving. We developed a new process of spacer for flexible display to improve the maintenance of cell gap. This new process used the laser carving technology, which is widely applied on printing press, to produce the pattern of spacers and shaped both of the alignment film and spacers simultaneously by press of pattern. Assembling the spacer-shaped film and plastic substrates together well and it shows an excellent performance on the maintenance of cell gap and reliability of curving.

• Steel and Composite Structures
• /
• v.29 no.2
• /
• pp.161-173
• /
• 2018

Point bending is often used for cambering and curving structural steel girders. An analytical solution, applicable in the elasto-plastic range only, that relates applied loads to the desired curve was recently developed for inducing horizontal curves using four-point bending. This solution does not account for initial residual stresses and geometric imperfections built-in hot-rolled sections. This paper presents results from a full-scale test on a hot-rolled steel section curved using four-point bending. In parallel, a numerical analysis, accounting for both initial geometric imperfections and initial residual stresses, was carried out. The models were validated against the experimental results and a good agreement for lateral offset and for strain in the elasto-plastic and post-plastic ranges was achieved. The results show that the effect of initial residual stresses on deformation and strain is minimal. Finally, residual stresses due to cold bending calculated from the numerical analysis were assessed and a revised stress value for the service load design of the curved girder is proposed.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.162-168
• /
• 2007

The critical speed above which the vehicle become unstable should be fundamentally verified in the development of new train. In case of high speed tilting train, which require both higher critical speed and higher curving speed, the critical speed should be more carefully treated because the both requirements are conflicting each other in the conventional train design. This research has been performed to estimate the linear and non-linear critical speed of 200km/h Korean Tilting Train which has been developing. The newly developed self-steering mechanism was attached to the tilting train to secure critical speed under the lower yaw stiffness which was inevitable to secure higher curving performance. The simulation to predict critical speed was done by commercial vehicle dynamic S/W. Full scale roller rig test was carried out for the validation of numerical results and effectiveness of self-steering mechanism.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1995.10a
• /
• pp.136-142
• /
• 1995

The kinematically admissible velocity field is developed for the analysis of extruded products. The curving of product in extrusion is caused by the linearly distributed longitudinal velocity on the cross-section of the workpiece at the die exit. In the analysis, the longitudinal velocity in extrusion direction is divided into the uniform velocity and the deviated velocity. In order to satify the requirement of the kinematically admissible velocity field, the average value of the deviated velocity should be zero. At the same time, it should Iinearly change with the destance from the center of gravity of the cross-section of the workpiece. The results of the analysis show that the curvature of product incresses with increses in eccentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-sectio at the die exit.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1550-1556
• /
• 2009

The sophisticated technologies, ensuring both stability and curving performance, are required for the medium high speed train running on conventional railway line where tangent and curved section mixed together. We can hardly meet the both requirements conflicting each other with the conventional type of bogie. Effective solution is to apply stabilizing mechanism for the bogie design, which increase hunting stability or dynamically critical speed while maintaining curving performance. In this research the numerical analysis by means of multi-body dynamic simulation S/W, experiments by using roller test rig and main line running test have been comprehensively performed for the 200km/h Korean Tilting Train with newly developed stabilizer. The paper proposes the effectiveness of stabilizer and its usefulness based on the results of analyses.

• Proceedings of the KSR Conference
• /
• 2003.10c
• /
• pp.611-616
• /
• 2003

The application of the tilting train is one of the most efficient ways to increase curving speed of train on existing tracks or on mountain railway lines with sharp curves. It can increase the running speed and ensure the passenger comfort and safety at the same time. Therefore, the development of tilting train has been paid high attention by many countries in the world. Tilting trains have been operated successfully in many countries such as Italy, Spain, Germany, Sweden, England and so on. The tilting trains possess broad prospects in raising speeds. The distributed EMU tilting train set will be developed according to the Korea railway conditions and will be operated on the Honam line, Janghang line and Jungang line. Because there is high percentage of curves on these lines. these lines are suited to operating tilting trains to raising speed and saving passenger traveling time. In order. to improve the curving performance of the tilling train. the active-control algorithm is utilized for the tilting bogie.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.1075-1076
• /
• 2009

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.6
• /
• pp.827-832
• /
• 2013

In this study, curve responsiveness was assessed based on the lateral force and running safety was evaluated based on the wheel unloading ratio and derailment coefficient, which is the ratio of the wheel load and the lateral force. The evaluation of the curving performance and running safety of the new high-power electric locomotive showed that the derailment coefficient appeared higher when the wheel-set was set to the front of the train instead of being placed backward, and the maximum value of the derailment coefficient was recorded as 0.572 on the Gyeongbu line. Furthermore, the lateral force increased in curved sections, and it appeared to be proportional to the curve radius. Meanwhile, a maximum axis lateral force of 77.6 kN was recorded on the Taebaek line, and the wheel unloading ratio was 47.6% on the Yeongdong line. Finally, the running safety at the maximum speed as well as the through-curve performance of the curve radius satisfied the required standards.

• Journal of the Korean Society for Railway
• /
• v.10 no.5
• /
• pp.613-618
• /
• 2007

The performance of the railway bogie is classified into the stability and the steering performance. Testing for the bogie stability is conducted on the roller rig, but testing for the bogie steering performance on test facility is very difficult, so the testing for the vehicle curving performance is conducted on the real curve track. Testing the railway bogie on the full scale test rig is desirable, but it caused many problems relating to test costs and test time. As a possible alternative to overcome these problems, a small scaled test rig is actively used in the field of bogie stability. Thus, in this paper, we have studied a scaled track to test the bogie steering performance. For this purpose, we designed the 1/5 scaled test track equivalent to radius 200 curve and confirmed the validity of the testing for the bogie steering performance on the sealed curve track through the testing using 1/5 scaled bogie.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.05a
• /
• pp.431-432
• /
• 2010