• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.232-240
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• 2015

Two types of track circuits are used in high speed railway car depots: one is High Voltage Impulse Track Circuit(HVITC); the other is AF track circuit. HVITC detects train occupation of blocks and broken rail; the AF track circuit is used for train onboard control system pretesting before departure. This testing is used to transmit train control information through the AF track circuit. The two systems are switched in turns for testing. We propose a system in which the AF track circuit is replaced by a loop cable that is installed on the inside rail; as such, engineers do not need to switch the systems. In cases in which the two systems run simultaneously, mutual interference may occur. In this paper, we identified this mutual interference by modeling of the two circuits.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.500-503
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• 2010

Until now, the track circuit with railroad which is a part of an electrical circuit wad used only for the detection of the train location, but as train speed is up to be higher, in order to overcome the limits of ground signal system the railway signal system has changed from the ground signal system to a cab signal system. The power source of the track circuit has also changed from a direct current or a high voltage impulse to an alternating current with high frequency which is a part of the audio frequency. To improve the maintenanability and according to the environment condition, the railway roadbed is rapidly changed to the ferroconcrete roadbed. In case of a track circuit to use an alternating current with high frequency as power source at a ferroconcrete roadbed, the characteristic of the track circuit is brought on a change from a loss of the magnetic combination instead of a leakage current from electric insulation which was caused by the reinforcing iron pod with lattice shape for durability. This paper is shown the influence and the loss of the signal current at AF track circuit on a ferroconcrete in the simulation sheets and presented a proposal for the preventive method from reduction of signal current.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.2
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• pp.70-75
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• 2014

A track circuit is a critical piece of equipment that allows the existence of the trains on the track to be detected. Train detection is very important for the signal safety equipment. It allows for the confirmation of a train's location, the locking of switch points, the coordination of safe distance between trains, and the advance notice of a train's arrival. Track circuits can be powered by AC or DC. The DC track circuits are usually used on non-electrified tracks. On these tracks, many signal errors can be caused by lightning or problems with the power source. These problems can also cause damages to the rectifiers which must be repaired or replaced, promptly. This issue is especially problematic in the summer because of the higher frequency of thunderstorms. Issues with track circuits also cause problems for other equipment, such as railroad crossings and switch points. This further disrupts the safe operation of trains. This study aims to enhance maintenance efficiency and improve safety by utilizing parallel operation and multiplexing of a DC track circuit as well as installing an external surge protector. The experimental results on the operation of the proposed method is also presented.

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.4
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• pp.537-542
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• 2014

Track circuit is a simple electrical device which lies in the connection of the two rails by the wheels and axle of locomotives and rolling stock to short out an electrical circuit, used to detect the absence of a train on rail tracks. In railway signaling system, there are similar systems such as RFID and wheel sensor, GPS etc, are research and developing. Hybrid track circuit is using RFID antenna and reader on the cab and RFID tag on the sleeper. because of the safety in railway operation, tag detection of train position detection function in the hybrid track circuit needs high reliability. This paper studied tag recognition enhancement used tag angles.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1701-1706
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• 2007

Jointless AF(Audio Frequency) Track Circuit is more comfortable than exist joint track circuit. This electrical circuit's function is detection train on rail, and transmit information between wayside and vehicle. 'Korea Railroad Corporation' proposed for revision of the Korean railway standards(KRS SG 0038-06 R, 2006.5.16) "Non-insulated AF Track Circuit". This proposal equipment developed to extend use for station of National Railway exist line. According to test standards Korean railway safety law and its ordinances, which were committed to Korea Railroad Research Institute, the professional committee 'Railway facility sector II' have helded on January in 2007. In this investigation, the changed test norm will be review the difference of important function test standards of new version to conform effectivity and safety test procedure according to the KS A 1025.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.471-477
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• 2013

We have studied on the possibility of precise positioning using hybrid Track Circuit system. Hybrid Track Circuit uses RFID which replaces UHF. Hybrid Track Circuit is a part of next generation railroad signal system which is available to communicate with a railway on board system based on a realtime operating system. If applicate on a current hand operating subway, phenomenon caused by driver's mistake such as passing a stop without stopping or mismatch error between PSD and train door should be prevented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.698-704
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• 2012

Electric power used in electrical vehicles flows into the substation through the feedback circuit, track circuit. Due to these power conversion equipments in electrical railroads, return current contains harmonics, and it should not affect other communication lines. In this paper, based on the return currents, we measured harmonics and analyzed an influence in railway equipments due to the harmonics. For analysis, we utilize the measured values of return currents measured in track circuits, and predictive values of those compared to the earth methods between the existing electrified sections. Applying the regulations used for Gyeongbu HSL(High Speed Line), the results of measured harmonics have found to be acceptable.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1469-1470
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• 2010

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.122-128
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• 2012

Considering structure of depot, it is impossible to install the track circuit systems due to iron-beam. Because rails and earth are connected by the iron-beam, there is much leakage current. So, it is hard to apply the track circuit systems. Thus, when trains go to the depot, sign which indicates existence of trains is used manually. In case of wrong sign, accidents occur such as train crash, derailment etc. Currently, location of trains has been found by using optical sensor in the depot to prevent the accidents. However, it costs a great deal to install and maintain the optical sensor. Therefore, this method is hardly used in train operation institutes. In this paper, virtual track circuit systems are introduced by using software program in the depot. Also, algorithm of the virtual track circuit systems is proposed. In case that signal is handled to the depot which is occupied by the train, safety is ensured by indicating sign which means existence of trains and stop signal. Also, proper fault tolerance techniques are proposed to the software by analyzing reliability and availability.