• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.1-8
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• 1999

In this paper, descibed was the derived algorithm for calculating contact point between wheel and rail and the developed method for rail modeling. The proposed methods use travelling distance to represent rail center line position vector and rail orientation with respect to Newtonian reference frame. The methods call be easily used ill multibody dynamic analysis. Two numerical examples are shown to verify the validity of the proposed methods.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.329-335
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• 2014

A maglev vehicle of middle-low speed subjected to both a lift force and a guidance force by a U-shaped single electromagnet is operated over a curved guideway without a guidance controller. Therefore, it is required to carefully decide the curve shape for preventing contact between the vehicle and the guiderail for the case that a Maglev vehicle is operated over a curved guideway with a small radius. Specifically, the shape of the transition curve is very important from the stability viewpoint. This study analyzes the influence of curve shape on maglev stability through parametric composition of the transition curve during vehicle guidance. To this end, a multibody dynamics-based threedimensional Maglev vehicle model was developed. The model was integrated with the vehicle, curved guideway, electromagnets, and their controllers. Using this model, a realistic parametric study including the curved guideway was carried out. The results of research should be considered usefully in the design of bogies and the curve shape.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.15-24
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• 2015

In magnetic levitation vehicles, the clearance between the magnet and track should be maintained within an allowable range through a feedback control loop. The flexibility of the guideway would introduce additional modes in the overall suspension system, resulting in dynamic interaction between the guideway vibration and the electromagnetic suspension control system. This dynamic interaction can be a serious problem, particularly at very low speeds or standstill, and may cause airgap instability. To optimize the overall system dynamics, an integrated dynamic model including mechanical and electrical parts and a flexible guideway as well as a control loop was developed. With the proposed model, airgap simulations at standstill were performed while varying the control gains, specifically with the aim of understanding the effects of gains of the PID controller on the airgap variation. The findings may be used to achieve a stable levitation controller design.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.540-545
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• 2007

The tilting train is able to tilt its body towards the center of the turning radius, preventing roll-over of the train as it runs on a curved rail at high-speed. This train, widely accepted for commercial purpose internationally, is very beneficial in that the operating time is shortened without much capital investment to the infrastructure where there are many curved rails. Over several years, the Korea Railroad Research Institute (KRRI) has developed such a train. In this paper, the safety of the Korean tilting train express (TTX) is investigated using a dynamic simulation model. Since proper safety standards have not been established for the TTX, those for the Korean train express (KTX) is employed to analyze the safety and ride comfort of the TTX. This study is useful in predicting the behavior of the TTX and ride comfort, and conforms that designed TTX is stable enough to satisfy the safety standards. It would be useful to recommend proper normal operating speed and determine the maximum safety speed, according to the result. Furthermore, it would be possible to provide basic reference data when analyzing the dynamic effect of the catenary system and the fatigue of the bogie.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.175-185
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• 2015

Generally, in the train area, switch tracks have required high reliability because this system is directly associated with derailment. Especially, switch tracks of Maglev vehicles must be moved in terms of the whole geometric characteristics, in which the bogies are encased in the switch track. For this reason, switch track was constructed with steel lighter than concrete girders. But, the steel switch track was weak because of structural vibration as well as structural deformation. Therefore, it is important to predict the levitation stability when a vehicle passes over flexible switch track. The aims of this paper are to develop a coupled dynamic model to describe the relationship between a Maglev vehicle and switch track and to predict the levitation stability. In order to develop the coupled dynamic model, a three dimensional vehicle model was developed based on multibody dynamics; a switch model was made using the modal superposition method. And, the developed model was verified using comparison measured data.

• Journal of the Korean Society for Railway
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• v.5 no.3
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• pp.187-195
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• 2002

It is important to predict the crash behavior of trains to improve their crashworthiness. This paper investigates the simulation of high-speed train crashes in three dimensions using multibody dynamics. At present, little is known about three-dimensional crash simulations. This study shows that it is possible to simulate overriding and lateral buckling, including results from one- or two-dimensional simulations. Several parameters, however, such as computational time and large deformation of structures, need further investigation.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.18-24
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• 2015

Train positioning detection information is fundamental for high-speed railroad inspection, making it possible to simultaneously determine the status and evaluate the integrity of railroad equipment. This paper presents the results of measurements and an analysis of an inertial measurement unit (IMU) used as a positioning detection sensors. Acceleration and angular rate measurements from the IMU were analyzed in the amplitude and frequency domains, with a discussion on vibration and train motions. Using these results and GPS information, the positioning detection of a Korean tilting train express was performed from Naju station to Illo station on the Honam-line. The results of a synchronized analysis of sensor measurements and train motion can help in the design of a train location detection system and improve the positioning detection performance.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.243-250
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• 2007

In general the Maglev vehicle is run over the elevated track called guideway. Since the guideway is elevated, the flexibility of the guideway has an effect on the dynamic responses of a vehicle such as its stability and ride quality. To improve the running performance of the Maglev vehicle and design a cost effective guideway using the dynamic analysis, the dynamic analysis of the system requires the coupling model of the Maglev vehicle and guideway. A coupling model based on multibody dynamics is proposed and programmed. With the program, the UTM01, a low speed Maglev vehicle, is analyzed and discussed.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.116-121
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• 2005

In this report, numerical investigations have demonstrated, that the displacement underneath a moving loading reach a maximum value, if the speed of the load is equal to propagation velocity of the maximum wave. The load speed for which the maximum displacement occurs is called critical speed. The critical speed divides the velocities in a subcritical and a super-critical region. By means of calculations the dynamic behaviour of the slab track-soil is investigated. For concrete slab track dynamic wheel load are given in dependence of relevant excitation mechanismen and speed of the train. These loads can be used for the dimensioning of the track as well as far the prognosis of the vibrations at the track and the surrounding soil.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1447-1453
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• 2012

For an electromagnetic suspension (EMS)-type urban Maglev train using U-shaped electromagnets, both the vertical and the lateral air gaps for levitation are maintained only by the electromagnet. The train can run over curved rails without active lateral air gap control because the U-shaped electromagnet simultaneously produces both a levitation force and a guidance force, which is dependent on the levitation force. Owing to the passive control of the lateral air gap, the lateral vibration could exceed the limits of the lateral air gap and acceleration. In this study, dynamic analysis of a Maglev train is carried out, and the effectiveness of a lateral damper for vibration reduction is investigated. To more accurately predict the lateral vibration, a Maglev vehicle multibody model including air-sparing, guideway irregularities, electromagnets, and their controls is developed.