• Journal of the Korean Society for Railway
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• v.5 no.4
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• pp.231-236
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• 2002

Todays, crash safety requirements of the railway vehicle structures become important design criterion according to the increased driving speed and the lightweight construction. Although the crash analysis using computer simulation can be effectively applied to predict the crash performance of the railway vehicles in the early design stage, the optimized design w.r.t the crash safety could be realized by the crash tests with actual prototype vehicles. However, it is very expensive and time-consuming task to perform the crash test of the railway vehicles. As a measure to cope with the problem, in this paper, the scale modeling technique is suggested and experimentally verified to predict the impact energy absorption characteristics of full scale model of aluminum extrusions sub-structures and the high-speed railway vehicle structure.

• International Journal of Automotive Technology
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• v.3 no.3
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• pp.123-128
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• 2002

This paper presents the design of an active roll control system for a ground vehicle and an experimental study using an devised electric-actuating roll control system. Based on a three degree of freedom linear vehicle model, the controller is designed using lateral acceleration and rollrate feedback. In order to investigate the feasibility of an active control system, experimental work is carried out using a hardware-in-the-loop (Hil) setup which has been constructed by the devised electric-actuating system and the full vehicle model including tire characteristics. The performance is evaluated by an experiment using the Hil setup with limited bandwidth. Finally, in order to enhance the control performance in the transient region, a hybrid control strategy is proposed and evaluated.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.805-810
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• 2005

The main functions of suspension system of railway vehicle are isolating vibration from track irregularity to car-body for the Ride quality and keeping its stability with limitation of vehicle's movement. These two functions conflict with each other, then it is impossible to achieve both of performance with traditional passive suspension which has constant characteristics. So, to improve this situation the active suspension was suggested and in specially the semi-active suspension is noticed for its effectiveness on cost despite of its lower performance than full-active suspension. In this study the control logic made through LQG theory was designed with simplified vehicle model and variable damper model defined by $1^{st}$ order system, then the analysis of simulation results was done to understand influence on the performance of semi-active suspension with running conditions and response characteristics of variable damper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.581-587
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• 2013

In a magnetic train set composed of more than two cars, the installation of dampers between cars is carefully considered for improving both the ride quality and the safety, particularly during curve negotiation. In this study, a dynamic simulation of the ride quality and curve negotiation of a Maglev vehicle was carried out. The dynamic model is developed based on multibody dynamics. The presented full vehicle multibody dynamic model integrates the electromagnet model and its control algorithm. By using this model, the effects of the dampers are numerically analyzed. The proposed damper is installed on the vehicle and tested to analyze its effects. In this study, the simulation and measured results of the vehicle behavior and ride quality are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.31-41
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• 1997

Equations of motion for a 7 DOF full car model is developed in detail and used for the design of LQR based active suspension system. The frequency response to road disturbance input and the motion of a car passing unequal bumps were used to analyzed the dynamic characteristics of the 7 DOF full car with passive or active suspensions. The resulting linear equations of motion may be usefull in designing other types of active suspension.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2236-2245
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• 2011

This paper deals with the levitation force characteristics of electromagnet for MAGLEV vehicle application. The magnetic flux density distribution and levitation force characteristics of the electromagnet are investigated by means of equivalent magnetic circuit model. Firstly, we defined the aligned and unaligned electromagnet module for the full-electromagnet, and magnetic flux paths are represented for each model including leakage and fringing flux paths. Because of the analysis model contains both the permanent magnet and electromagnet coil, we calculated the airgap magnetic flux density and levitation forces using flux superposition in electromagnetic circuit. The results are validated extensively by comparison with finite element analysis. Moreover, the 1/4 scaled magnetic levitation and propulsion test vehicle has been manufactured and tested in order to verify these predictions. The experimental results confirms the validity of the analytical prediction with equivalent magnetic circuit model for the description of a electromagnet.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.1-9
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• 2012

The NCF control algorithm for an active suspension system was proposed and investigated. The NCF algorithm using spring dynamic variation force and suspension relative velocity was applied to the 1/4 vehicle model and numerical analysis was performed. Vehicle's performances such as vehicle displacement, vehicle acceleration, suspension deflection, tire deflection and absorbed power were calculated and compared with those of the passive, semi-active and LQR active suspension system that use full state feedback. Numerical results show that the proposed NCF active suspension system has superior performance compared with the passive and semi-active suspension system and has very similar performance compared with the LQR active suspension system. So the proposed NCF algorithm is considered as a highly practical algorithm because it requires only one displacement sensor in a 1/4 vehicle model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.684-690
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• 2006

This study proposes and validates a new column type electric power steering system (EPS-TT). It is driven by a uni-directional motor and two electro-magnetic clutches. The assist motor produces assist torque in only one direction and two clutches transmit the torque to the column of steering system in either left or right direction with respect to the steering input. A full order and a reduced order models are developed to evaluate the EPS-TT. Models are also used to investigate the vehicle responses. A PID control logic is designed to control the torque of the assist motor. A driver model is applied to the system and the resulting performances are analyzed. The results show that the performances of the full order model are similar to those of reduced order model. The results also prove that the performances achieved by the EPS-TT are improved compared to those of a conventional EPS-TT across the frequency domain.

• Structural Engineering and Mechanics
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• v.45 no.3
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• pp.337-354
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• 2013

For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel's service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors, including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1559-1565
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• 2013

This study aims to investigate the dynamic interaction characteristics between Maglev vehicles and an elevated guideway. A more detailed model for the dynamic interaction of the vehicle/guideway is proposed. The proposed model incorporates a 3D full vehicle model based on prototyping, flexible guideway by a modal superposition method, and levitation electromagnets including the feedback controller into an integrated model. The proposed model was applied to an urban transit Maglev developed for a commercial application to analyze the dynamic response of the vehicle and guideway, and the effect of the surface roughness of the rail, mid-span guideway deflections, and air gap variations are then investigated from the numerical simulation.