• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.1-5
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• 2005

High-speed trains with maximum speed of 300km/h, named KTX, have started revenue services since April 2004. Is becoming big problem where currently the KTX train because excessive braking noise at a station platform. The KTX braking noise follows in operating mode of KTX train and important railroad station where the quality appears different, the quality against hereupon from the commerce vehicle from the research which it sees it executes and comparison to analyze.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.955-960
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• 2011

This study was aimed at investigating the applicability of energy harvesting technologies, which are regarded as new and renewable energy sources for real-time/wireless monitoring of intelligent railroad vehicles. The surrounding energy generated in a normal operating environment was monitored using a high-speed railroad vehicle in operation. This monitoring was performed in an attempt to evaluate the effectives of energy harvesting and the applicability of energy-harvesting-monitoring technologies under the conditions in which thermal energy and vibration energy are generated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.902-910
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• 2016

This paper presents the overall measurement system for on-line test of super-speed maglev train. The super-speed maglev train is composed of vehicle, propulsion, power, and so on. In order to evaluate and diagnose for sub-system, we made overall measurement system. Just like the other measurement system, it is designed to distributed type. The hardware is consist of SCXI, PXI, Terminal, UPS, and so forth. It is installed on a train, control room, power room and track to collect lots of signals. The software controls hardware system, monitors main data such as inverter current, converter voltage. Using the measurement system, we evaluated a lot of performances for vehicle, track, and so forth. Through the developed system have improved reliability and safety for super-speed maglev train.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2215-2216
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• 2011

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to electrical railway vehicle is investigated from an electrical response point of view. To analysis voltage and current waveforms by induced contact loss phenomenon on driving electrical railway vehicle, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. Throughout prototype simulator and contact wire and catenary wire experiments, it is confirmed that current waveforms is distorted by contact loss phenomenon and in case of driving electrical railway vehicle.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.162-167
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• 2017

The chevron rubber spring is used for subway vehicle as a primary suspension. Generally, the primary suspension has an influence to the running performance and not so much effect on the ride comfort in railway vehicle. But the stiffness of chevron spring is harder and harder as time goes on because of rubber characteristics. Therefore the dynamic characteristics such as ride comfort and derailment coefficient should be reviewed according to the stiffness variation of chevron rubber spring. In this paper the effect of chevron rubber spring on dynamic characteristics was studied by considering multi-body dynamics of railway vehicle on one straight line and seven curved lines.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.21-29
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• 2015

For higher reliability against component failures in railroad trains with many electronic sensors and actuators, a distributed control system with which all electronic components are connected via a network is being considered. This paper compares and analyzes various topologies of Ethernet network for a railroad train in the aspects of (1) failure recovery, (2) the number of ports per device, (3) the number of cable connections between vehicles, and (4) performance. Especially, the unique characteristic of a train system that the number of vehicles changes is considered through analysis. Various combinations of in- and inter-vehicle topologies are considered. In addition, we introduce a hybrid of star and daisy-chain topology for inter-vehicle connection when the maximum number of inter-vehicle connections is limited to reduce possible failures of inter-vehicle connections. Simulation results show performance comparison between different topology combinations; the hybrid topology is shown to enhance delay performance even with a highly limited number of inter-vehicle connections.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.537-542
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.577-587
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• 2017

In the design process of dynamic characteristics of a railway vehicle, demand for analysis, testing and estimation methods of running stability are increasing as railway vehicle speed is increasing. Critical speed tests and estimation have been carried out using computer simulation or special test facilities, like roller rigs, because real track testing at critical speed is very dangerous. This paper introduces a test and assessment method for critical speed and estimates the validity using several roller rig tests. The test results show that it is difficult to estimate the critical speed using safety and instability assessment method in UIC 518, but that there is good agreement between the reduction of the equivalent damping ratio and the critical speed.

• Journal of the Korean Society for Railway
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• v.2 no.1
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• pp.28-37
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• 1999

Many residential areas are situated near to railroad tracks so that a railroad noise has been one of the major environmental issues. In this paper two important aspects have been investigated in order to properly evaluate the railroad vehicle noise : sound power levels for different types and sound propagation characteristics of the railroad vehicles. For noise source characteristics of railroad vehicles, sound power values for various types of trains that are in active service have been measured. In this paper, domestic railroad vehicles are measured and compared with high speed train(TGV). Based on sound power information of railway vehicles, prediction on the sound pressure level and equivalent noise level near to railway areas have been evaluated.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.828-830
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• 2009

In Korea, various efforts to cope with the Post-Kyoto system have been recently performed because a duty for the GHG(Greenhouse Gas) reduction may be allocated from 2013. Especially, the role of railroad has been strengthened to decrease total GHG emission of transportation system. Therefore, it is necessary to investigate the GHG emission and the reduction strategies of railroad. The purpose of this study was to develop the calculation method of GHG emission released from railroad. Main source of GHG emission was the energy consumption of railroad vehicle and infrastructure. Based on the emission factor and the equation reported in IPCC 2006 guideline, the total GHG emission of railroad was about 1.4 million tons CO2e in 2007. Using this calculation method, the GHG data of railroad can be calculated quantitatively and managed systematically in the future.