• Proceedings of the KSR Conference
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• 2005.11a
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• pp.332-337
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• 2005

In order to investigate performance changes, the acceleration, vibration, and braking performance tests were carried out on the electric multiple units (EMUs) with over 20 years operation. According to the testing results, in vibration and braking performance, the similar performance results were obtained as compared with newly manufactured EMUs. However, in terms of acceleration performance, below reference value (3.0 km/h/s) has been obtained. This is mainly due to performance deterioration including traction motor. The precision diagnosis evaluation of deteriorated EMUs will be provided through the overall evaluation of corrosion testing and structural performance of car body.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.330-335
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• 2002

To estimate the reliability of the standard electric multiple unit developed by Korea Railroad Research Institute, the vehicle system composed of 4 cars is divided into 14 subsystems. The 14 subsystems are connected in series. For each subsystem except for car body and bogie, failure rate is evaluated by an optimal failure model used in reliability engineering. For car body and bogie probabilistic structural integrity analysis is carried out. The distribution of failure rate of each part and system is assumed to be exponential. The estimated MTBF of the vehicle satisfies the planned MTBF.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.220-224
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• 2002

As the train run through the tunnels, especially at high speed, pressure shock developed by the running train gives the influence on the pressure fluctuation inside the tunnel and consequently, inside the car. This pressure changes and pressure gradient is closely related with the tunnel section, train speed, air tightness of the train, length of the tunnel, etc. This study includes the analysis of the pressure behavior at the varied train speed and tunnel length. The results show that train speed affects the pressure gradient inside the car almost linearly, and that there exist the critical tunnel lengths that gives the maximum value of pressure change and pressure gradient, respectively.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.560-567
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• 1998

The pitch of spot-weld is a important variable in a view of both production cost and strength of car-body. Various renditions for the selection of pitches have been researched and especially in this paper the buckling analysis is carried out for the 2-sheet pannel structures. The optimal pitch is obtained by optimization program and FEM, which can enhance the buckling strength.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.137-143
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• 1998

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of traction motor for electric car SIMPLE algorithm based on finite volume method is used to make linear algebra equation. The governing equations are solved by TDMA(TriDiagonal Matrix Algorithm) with line-by-line method and block correction. From the results of simulation, the characteristics of cooling pattern is strongly affected by the size of hole in stator core. In the case of high rotational speed of rotor, temperature difference along the axial direction is more decreased than that of low rotational speed.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.233-240
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• 1998

This paper presents a high efficiency low switching PWM technique for the propulsion system of Electric car. In order to achieve the continuous voltage control to six-step and a low harmonics with low switching frequency under 500㎐, the synchronous technique is combined with a space vector overmodulation and implemented by using DSP. Improved performance and a validation of proposed method is shown by the experimental results using a 1.65MVA IGBT VVVF inverter and inertia load equivalent to 160 tons electric cars.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.519-525
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• 1999

This paper describes a crashworthy design for the front structure of KHST (Korean High Speed Train) under the SNCF accident scenario (collision against a movable rigid mass of IS tons at 110 km/h). The front structure designed in a new concept shows good behaviours in crashworthy point of view. It collapses in a progressive and well-controlled fashion. To evaluate the design by considering real situations, the power-car is simulated for accidents collided against a dump truck of 15 tons at 110 km/h. The front end structure of it shows a good response on crashworthiness.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.130-138
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• 1999

This study was carried out about interior design of trailer car for Korean High speed Train of Maximum operating speed of 350km/h. The interior main item design of high speed train is performed in order to satisfy the function of speed, safety and comfort concerning the RAMSH, ENVIRONMENT, ACTIVITY AND INFORMATION, This paper focuses on what is the design principle concerning the above mentioned factors and how did we apply that in the korea high speed train.

• Structural Engineering and Mechanics
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• v.61 no.6
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• pp.775-784
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• 2017

This study is devoted to developing many new substructure models for ballasted railway track by using the pyramid model philosophy. As the effect of railway embankment has been less considered in the previous studies in the field of vehicle/track interaction, so the present study develops the pyramid models in the presence of railway embankment and implements them in vehicle/track interaction dynamic analyses. Considering a moving car body as multi bodies with 10 degrees of freedom and the ballasted track including rail, sleeper, ballast, subgrade and embankment, two categories of numerical analyses are performed by considering the new substructure systems including type A (initiation of stress overlap areas in adjacent sleepers from the ballast layer) or type B (initiation of stress overlap areas in adjacent sleepers from the subgrade layer). A comprehensive sensitivity analyses are performed on effective parameters such as ballast height, sleepers spacing and sleeper width. The results indicate that the stiffness of subgrade, embankment and foundation increased by increasing the ballast height. Also, by increasing the ballast height, rail and ballast vertical displacement decreased.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.337-342
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• 2003

The dynamic load effects are conveyed to the railway bridges through tracks which are generated by moving trains The dynamic load effects may vary due to the dynamic characteristics of the applied vehicle loads and the railway bridges containing the track system. However, the track effects have been neglected or simplified by spring elements in the most studies since it is quite complex to consider the track systems in the dynamic analysis models of railway bridges. In this study, track system on railway bridges is modeled using a three-dimensional discrete-support model that can simulate the load carrying behavior of tracks. In addition, this program is developed with the precise 20-car model and a continuous PSC(prestressed concrete) box girder bridge, which is the main bridge type of Korea Train express(KTX). Three-dimensional elements are used for both. The dynamic response of railway bridges is found to be affected depending on whether the track model is considered or not. The influencing rate depends on the traveling speed and different wheel-axle distance. The dynamic bridge response is decreased remarkably by the track systems around the resonant frequency. Therefore, the resonance effect can be reduced by modifying the track properties in the railway bridge.