• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.445-455
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• 2016

A goal of the Real-time railway safety supervision system is to improve the safety oversight efficiency and to prevent accidents by integrating existing distributed monitoring systems, train, signal, power and facilities. So, the system require better performance regarding real-time processing based on big data. The disk-based database that is used in existing railway control systems has a problem with real-time processing; memory-based databases haves a limitation in terms of big-data processing; and time series databases haves a limitation in terms of real-time processing. So, we need a new database architecture for simultaneous real-time processing based on big data. In this study, we review the existing railway monitoring systems and propose a new database architecture for a real-time railway safety supervision system.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.384-389
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• 2011

The electric railway cars are operated by high voltage supply through the catenary wire. Also, numerous electric equipments operated by electric signal are distributed in the electric railway cars. Such electric equipments are exposed to EMI/EMC problems, and there is the possibility that the magnetic field due to the catenary wire current takes effect on the electromagnetic field in the electric railway cars which move under the catenary wire. There is the possibility that the electromagnetic interference generates in view of the operation of many electric equipments in the electric railway cars. There is the possibility that the communication device faults generate, and that the hazards on the human beings generate. In this paper, we predict the magnetic field around the catenary wire, and obtain the exact magnetic field distribution by comparing the analytic results and the numerical results. Finally, we confirmed the possibility of the passive loop mitigation by comparing the analytic results and the numerical results through the passive loop mitigation technique.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.754-760
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• 2008

For monitoring of railway structures, optical fiber sensors are very convenient. The fiber sensors are very small and do not disturb the structural properties. They also have several merits such as electro-magnetic immunity, long signal transmission, good accuracy and multiplicity of one sensor line. Strain measurement technologies with fiber optic sensors have been investigated as a part of smart structure. In this paper, we investigated the possibilities of fiber optic sensor application to the monitoring of railway structures. We expect that the fiber optic sensors have much less noises than electrical strain gauges because of electro-magnetic immunity while railways operate electric power of 22000 volts. Fiber optic sensors showed good durability and long term stability for continuous monitoring of the railway structures as well as good response to the structural behaviors during construction.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.96-101
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• 2009

In this study, a risk-appearance frequency evaluation model for railway level-crossing accidents is developed with the frequency estimation based on the accident history. It follows the worldwide common safety management approach and reflects the operation conditions and accident properties of the domestic railway system. The risk appearance frequency evaluation process contains a development of accident scenarios by defining the system configurations and functions, and a frequency estimation of hazardous events based on the accident history. The developed model is verified with the accident history during 5 years('03-'07) for 3 hazardous events: 'Being trapped in level crossing(Hl)', 'Crossing during warning signal(H2)' and 'Breaking through/detouring the barrier(H3)'. This risk appearance frequency evaluation model will be combined with a consequence evaluation model so as to offer full risk assessment for the railway accident. The accident risk assessment will contribute to improving the safety management of the railway system.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.737-747
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• 2011

5678SMRT has installed various sensor for operating conditions(field of electric, facilities, signal, communication equipment and track) and environment of Every Function Room for remotely detecting and monitoring. Installed sound sensor for analyzed after remotely heard the noise of every equipment at Every Function Room and temperature sensor for check the temperature condition of Every Function Room. Additional installed voltage sensor in signal equipment room for monitoring RF track-circuit's voltage condition. Installed displacement sensor at The Chungdam bridge's railway for measuring and monitoring track displacement caused by temperature change and Pan/Tilt camera at sub-station and drainage for remotely field monitoring. Installed sensor for each equipment's operating condition and failure at Every Function Room then periodic check of workforce turned to around-the-clock surveillance by sensor therefore improvement of operating equipment. SMRT is lots of prevent a failure by Immediately detect of precondition of equipment failure by analyzed the sensor data. If the occurrence of an failure, become detected Immediately so possibility correct diagnosis and order by remotely field check by installed camera and sound sensor at field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.147-155
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• 2010

We studied on performance improvement of TTM(TI21 Test Meter) that is test and diagnosis devices for jointless audio frequency track circuit on Korean electric railway TI21 standard. Upgraded devices is AD-TTM(Advanced TI21 Test Meter). This can measure alternating frequency USB(Upper signal band) and LSB(Lower signal band). In the audio frequency track circuit, ${\pm}17[Hz]$ of nominal frequency are demodulated and supplied to track relay through AND gate. It is important that measurement function which is error between USB and LSB. Need of AD-TTM will stand out in the electric railway system because this is simple and accurate rather than the former device.

• Journal of the Korean Society for Railway
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• v.2 no.1
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• pp.38-46
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• 1999

This study proposes the analysis and evaluation method of time series ultrasonic signal using the attractor analysis. Features extracted from time series signal analyze quantitatively characteristics of weld defects. For this purpose, analysis objective in this study is fractal dimension and attractor quadrant feature. Trajectory changes in the attractor indicated a substantial difference in fractal characteristics resulting from distance shifts such as parts of head and flange even though the types of defects are identified. These differences in characteristics of weld defects enables the evaluation of unique characteristics of defects in the weld zone. In quantitative fractal feature extraction, feature values of 3.848 in the case of part of head(crack) and 4.102 in the case of part of web(side hole) and 3.711 in the case of part of flange(crack) were proposed on the basis of fractal dimensions. Proposed attractor feature extraction in this study can enhance the precision rate of ultrasonic evaluation for defect signals of rail weld zone such as side hole and crack.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.147-155
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• 2001

A data acquisition and signal processing system for evaluating the current collection system is developed, and subsequently applied to the measurement and analysis of the contact force in the current collection system of the proposed Korean High Speed Railway. The measurement of the contact force is based on an algorithm that employs the relationship between the contact force, the strain due to the bending moment and the panhead inertia. For the contact forces in the frequency range of less that 50Hz, the panhead can the modeled as a rigid body in the inertia calculation. For higher frequencies however, the bending vibration modes of the panhead need to be accounted for as well.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.831-835
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• 2005

In a signal control of the railway system, the first objective is to guarantee a safety of the train operation, and the second is to increase a frequency(a capability of the transportation) of the train operation. In order to express the capability of the transportation a terminology what is called a railroad line capacity is employed. The railroad line capacity means a maximum frequency of the train operation in a possible schedule of the one way operation for one day. During the last several years an improvement in the facilities of the train operation (railroad line extension, improvement in the stations, improvement in the signal facilities) has been achieved to increase the railroad line capacity. In this paper the authors deal with the case analysis which try to shorten headway and which has an impartible relation with increasing of the railroad capacity

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.367-369
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• 1997

In signal system such as MAGLEV, the transmission channel that has wireless transmission line between on-board and ground-site is susceptible to have interference and may introduce data error on transmission. In this paper, by applying inductive wireless and FSK(frequency shift keying) modulation using widely in railway signal system, we intend to analyze the data transmission characteristics. In this case, noise may have effect on transmission channel. Therefore transmission channel should be lessened the data error from random noise. Considering the transmission medium, the objective of this study is to analyze the transmission characteristics between on-board and ground-site and to obtain transmission performance.