• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1292-1294
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• 2002

In this study, the block section length of the given area has been analyzed to improve the headway which caused by the mixed operation of high speed trains and normal trains on the electrified railway of Dongdaegu to Busan. After establishing the average length of block section and the adjustable average length of block section of Dongdaegu to Busan, it is possible to perform the headway simulation regarding the signal system based on the established length. Although high speed trains as well as low speed trains including freight trains operate together, the experimental results indicate that the modification of the block section length shows the possibility of the improvement of headway.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.387-392
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• 2004

There has been an increasing demand for the noise impact assessment by the high-speed trains due to the expansion of high-speed rails. This paper provides procedures for the evaluation and the assessment of the potential noise impact resulting from proposed high-speed rails. Firstly the official specifications for the railway noise have been reviewed, and the procedures for the initial noise evaluation and the detailed noise analysis have been described.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.694-701
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• 2013

The gear-reduction units of Korean high-speed trains consist of a motor reduction unit, an axle gear box reduction unit, and a tripod joint shaft. A reduction gear unit is a gearbox used to reduce the rotational speed of the input shaft to a slower rotational speed on the output shaft. This reduction in output speed helps to increase torque. Defective reduction gear units in high-speed trains are caused by damage to the gear or by gear fatigue. To diagnose potential problems, it is important to know the vibration characteristics of the reduction gear units. In this study, we analyzed the vibration characteristics of reduction gears under various conditions. The test setup included a full-scale test rig to evaluate reduction gear under both normal and extreme operating conditions.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.841-848
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• 2008

This paper examined dynamic characteristics of high speed trains using a time varying frequency transform. Fourier transform based methods are frequently used for the calculation of the dynamic characteristics of trains in the frequency domain, but they cannot represent the time-varying characteristics. Therefore it is necessary to examine their characteristics using a time-varying frequency transform. For the examination, the non-stationary vibration of wheelset, bogie, and carbody are measured using accelerometers and stored in a data aquisition system. They are processed with localization of the data by modulating with a window function, and Fourier transform is taken to each localized data, called the short-time Fourier transform. From the processed results, time varying auto-spectral density, cross-spectral density, frequency response, and coherence functions have been calculated. From the analysis, it is confirmed that the time varying frequency transform is a useful method for analyzing the dynamic characteristics of high speed trains.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.362-368
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• 2005

The KTX is now operating to the commercial purpose at Gyeong-Bu high speed railroad and Ho-Nam conventional railroad to be started on April, 2004. The trains were not found any problems at high speed railroad, but at Ho-Nam line were known to be have the few problems due to operating no planed. In this report should be studied for the effects of the lateral forces and wheel bases, brake distances etc., that high speed trains should be considered on curve running at the conventional railroad. The studied contents for operating at the conventional railroad shall be checked for the technical requirements from design stage, and the trains should be supplied and manufactured to car system to have the good running performances.

• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.18-25
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• 1999

A high speed train named Korean High Speed Train (KHST) with its maximum operating speed 350 km/h is now under development. For the successful design of a quiet and comfortable high speed train, it is important to understand the general features of the noise and vibration characteristics of high speed train. This paper reviews extensively collected materials on the noise and vibration characteristics of existing high speed trains. Based on the noise and vibration characteristics of TGV systems, a simple indoor-noise prediction rule is proposed for the TGV-type high speed trains such as KHST The indoor-noise of KHST at 350km/h is expected to be larger than at least 71 dBA. Some important researches conducted for designing KHST during last two years under the G-7 project are also briefly introduced at the last part of this paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.136-145
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• 2009

This paper proposes control methods and simulation models of a driving system, which consists of converters and inverters, for high speed trains employing multi-level power converters. The control method of a single phase three-level converter for high-speed trains is designed to use DC values instead of instantaneous current values which are usually used in single-phase application, so that it results in a fast and robust voltage control response. In addition, simulation models of Space Vector Pulse Width Modulation (SVPWM) for single phase three-level converters as well as three level inverters are proposed. Experimental results demonstrate the validity of the simulation model for three-level inverters.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.199-219
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• 2015

This paper presents the non-destructive evaluation of a high-speed railway bridge using train-induced strain responses. Based on the train-track-bridge interaction analysis, the strain responses of a high-speed railway bridge under moving trains with different operation status could be calculated. The train induced strain responses could be divided into two parts: the force vibration stage and the free vibration stage. The strain-displacement relationship is analysed and used for deriving critical displacements from theoretical stain measurements at a forced vibration stage. The derived displacements would be suitable for the condition assessment of the bridge through design specifications defined indexes and would show certain limits to the practical application. Thus, the damage identification of high-speed railways, such as the stiffness degradation location, needs to be done by comparing the measured strain response under moving trains in different states because the vehicle types of high-speed railway are relatively clear and definite. The monitored strain responses at the free vibration stage, after trains pass through the bridge, would be used for identifying the strain modes. The relationship between and the degradation degree and the strain mode shapes shows certain rules for the widely used simply supported beam bridges. The numerical simulation proves simple and effective for the proposed method to locate and quantify the stiffness degradation.

• Smart Structures and Systems
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• v.21 no.5
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• pp.705-713
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• 2018

High-speed rail (HSR) has been in operation and development in many countries worldwide. The explosive growth of HSR has posed great challenges for operation safety and ride comfort. Among various technological demands on high-speed trains, vibration is an inevitable problem caused by rail/wheel imperfections, vehicle dynamics, and aerodynamic instability. Ride comfort is a key factor in evaluating the operational performance of high-speed trains. In this study, online monitoring data have been acquired from an in-service high-speed train for condition assessment. The measured dynamic response signals at the floor level of a train cabin are processed by the Sperling operator, in which the ride comfort index sequence is used to identify the train's operation condition. In addition, a novel technique that incorporates salient features of Bayesian inference and time series analysis is proposed for outlier detection and change detection. The Bayesian forecasting approach enables the prediction of conditional probabilities. By integrating the Bayesian forecasting approach with time series analysis, one-step forecasting probability density functions (PDFs) can be obtained before proceeding to the next observation. The change detection is conducted by comparing the current model and the alternative model (whose mean value is shifted by a prescribed offset) to determine which one can well fit the actual observation. When the comparison results indicate that the alternative model performs better, then a potential change is detected. If the current observation is a potential outlier or change, Bayes factor and cumulative Bayes factor are derived for further identification. A significant change, if identified, implies that there is a great alteration in the train operation performance due to defects. In this study, two illustrative cases are provided to demonstrate the performance of the proposed method for condition assessment of high-speed trains.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.222-230
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• 2003

Artificial intelligence has been used in the configuration design stage of high-speed train. The traction system of a high-speed train is composed of transformers, motor blocks, and traction motors of which locations and number in the trainset should be determined in the early stage of the train conceptual design. Components of the traction system are heavy parts in the train, so it gives strong influence to the top speeds and overall train configuration of high-speed trains. Top speeds have been predicted using the neural network with the associated data of the traction system. The neural networks have been learned with data sets of many commercially operated high-speed trains, and the predicted results have been compared with the actual values. The configuration design of the train set of a high-speed train determines the basic specification of the train and layout of the traction system. The neural networks is a useful design tool when there is not sufficient data for the configuration design and we need to use the existing data of other train for the prediction of trainset in development.