• Journal of Energy Engineering
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• v.24 no.1
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• pp.10-16
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• 2015

Recently, RCM(reliability centered maintenance) process is introduced and applied for the planning and implementing efficient and effective maintenance system in terms of optimal rolling stock maintenance. Particularly, cost-time benefits analysis associated with the implementation of RCM for rolling stock maintenance is necessary and required for railway operator in advance. The RCM process was primarily starting from military, airplane and nuclear industries and is now adapted in railway industry for local railway operators. This paper focuses on suggesting the way of connecting the RCM process with railway maintenance activities in the railway operation field. Thus, in order to introduce and establish reliability activities, it needs to review and evaluate the maintenance environment in the organizational point of view. Based on these reviews and evaluations, various maintenance methodologies are reviewed for customizing local railway field situations and establish specific process in the application of major systems on the reliability technology. In this paper, the railway RCM process is proposed for the establishment and construction of the systematic and optimal maintenance system.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.157-167
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• 2008

Through this study, the standard design guidelines for high speed train with power cars have been derived to meet the crashworthiness requirements of the Korean rollingstock safety regulation. The crashworthiness regulation requires some performance requirements for two heavy collision accident scenarios; a train-to-train collision at the relative speed of 36 kph, and a collision against a standard deformable obstacle of 15 ton at 110 kph. A standard high speed train composition was defined as 2PC-2ET-6T with 17ton axle load, similar to KTX-2 for the Honam express line. Using theoretical and numerical analyses, some crashworthy design guidelines were derived in terms of mean crush forces and energy absorptions for major crushable components. The derived design guidelines were evaluated and improved using one dimensional spring-mass dynamic simulation. It is shown from the simulation results that the suggested design guidelines can easily satisfy the domestic crashworthiness requirements.

• International Journal of Railway
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• v.4 no.2
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• pp.42-49
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• 2011

Today, rolling stock has become a fast and convenient mode of transportation and has witnessed increased demand. But the speed improvement has resulted in increased aerodynamic noise and therefore residential districts near the railroad tracks are exposed to ever increasing noise level. A study on methodologies for measuring and appraising rolling stock's environmental noise has therefore become an important area of endeavor. In the case of the environmental noise, there are no changes in tone so prediction can be made by reducing areas around the railway. The present study explores estimation of the noise around the railway using scale model, and the source of the noise has been investigated as well. The scale model of rolling stock will have to be able to measure high frequency noise and it is required to be generated in a short amount of time. Since popping a balloon or firing a gun fits this requirement the present study analyzed the characteristics of these two different noise sources. Measurement was made in a large vacant lot and the reflection due to the ground was also examined. The method proposed here can be used in the future for predicting the environmental noise of railway vehicles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1535-1536
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• 2011

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.27-37
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• 2011

Currently, in the course of introducing rolling stocks, RAMS standard and management by system engineering method apply to rolling stock system. Technical elements and results applied in system introduction phase are just used in acquisition stage, and these are not applied to the standard in railway site. Therefore, it is difficult to apply to standardized technology and quality assurance measure. Due to the establishment of the EU, railway operation system is internationalized and the international railway standards are being discussed in various ways. In addition, standardization is expanded from manufacture to operation and maintenance. It is to provide consistent standard in quality, cost calculation of maintenance technology, maintenance technology and quality assurance in case of international railway safety incidents. Therefore, this study is to find technology, quality and cost management model to be used for choosing railway-operation guidance by considering how technologies & quality have changed in system life cycle, compared with estimated standards, based on the technologies & quality-related result in the process of getting new rolling stocks and management guidance for operation & maintenance process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.366-371
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• 2004

For the reduction and efficient management of railway noise, first of all prediction of railway noise is necessarily requisted. At home and abroad many studies for prediction of raiiway nearby noise have been accomplished. But it is impossible to predict easily and exactly for the Korean Railway, because the acoustic powers for each rolling stock operated in Korea have not been built yet. So in this study, prediction model equation for environmental noise for Korean rolling stock Mugungwha was suggested using SEL of engine and rolling noise component separately. In this prediction model, the number of car, distance from the rail can be considered. Finally for the validation of prediction nlodel equation, the predicted Leq was compared to the measured Leq.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.156-162
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• 2006

For the reduction and efficient management of railway noise, first of all prediction of railway noise is necessarily requisited. Many studies for prediction of railway nearby noise have been accomplished. But it is impossible to predict easily and exactly for the Korean Railway, because the acoustic powers for each rolling stock operated in Korea have not been built yet. So in this study, Prediction model equation for environmental noise for Korean rolling stock Saemaeul was suggested using SEL of engine and rolling noise component separately. Finally for the validation of prediction equation, the predicted result was compared to the measured.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.57-64
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• 2017

In order to reduce damages to major railroad components, which have the potential to cause interruptions to railroad services and safety accidents and to generate unnecessary maintenance costs, the development of rolling stock maintenance technology is switching from preventive maintenance based on the inspection period to predictive maintenance technology, led by advanced countries. Furthermore, to enhance trust in accordance with the speedup of system and reduce maintenances cost simultaneously, the demand for fault diagnosis and prognostic health management technology is increasing. The objective of this paper is to propose a highly reliable learning model using various machine learning algorithms that can be applied to critical rolling stock components. This paper presents a model for railway rolling stock component fault diagnosis and conducts a mechanical failure diagnosis of motor components by applying the machine learning technique in order to ensure efficient maintenance support along with a data preprocessing plan for component fault diagnosis. This paper first defines a failure diagnosis model for rolling stock components. Function-based algorithms ANFIS and SMO were used as machine learning techniques for generating the failure diagnosis model. Two tree-based algorithms, RadomForest and CART, were also employed. In order to evaluate the performance of the algorithms to be used for diagnosing failures in motors as a critical railroad component, an experiment was carried out on 2 data sets with different classes (includes 6 classes and 3 class levels). According to the results of the experiment, the random forest algorithm, a tree-based machine learning technique, showed the best performance.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.128-139
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• 1999

This paper proposes a linearization technique for the space vector modulation method, which increases the linear control range of inverter up to the 6-step inverter. This method is based on fourier series expansion of the desired output voltage of the inverter to calculate the compensation angle in continuous switching mode and holding angle in discontinuous switching including the 6-step mode respectively. The approximation equation of these angles are used for compensation of fundamental voltage in overmodulation range. Therefore, it is possible to obtain the linear control and the maximized utilization of PWM inverter output voltage.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.56-61
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• 2007

In the braking of railway rolling stock, the slip that is the relative velocity between train body and its wheel affects the adhesive force which is connected to the braking force. The coefficient of the adhesive force changes in accordance with the slip and the condition of a rail road. Namely, its value increases upon the maximum on a rail condition, and there it declines conversely while the magnitude of slip keeps rising on. First, this paper introduced a reference slip generator so that can utilize maximum adhesive forces with a disturbance observer for estimating unmeasurable current adhesive forces which is as an input of the generator. And, an adaptive sliding-mode control system has been synthesized for minimizing the error between reference and current slip. Finally the effectiveness of the proposed control system is evaluated by computer simulation.