• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.786-791
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• 2007

Aerodynamically generated noise is dominant when the train speed approaches 300km/h. This noise sources is caused by the turbulent flow separations or vortex shedding from the train structure. Experiments were performed to investigate the characteristics of aerodynamic noise sources generated from exterior of the KTX trains and HSR-350x, especially from the inter-coach spacing. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Effect of the size of the mud-flap has been investigated through an wind tunnel test and it has been found that the low frequency noise is strongly dependent on the size of the gap. Also performed is an array measurement to locate different noise sources from the high-speed train. spectral characteristics of exterior noise sources are examined.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.363-368
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• 2003

The Inter-laboratory comparison test which is demanded on the authorized test of ISO 17025 is the program to guarantee the reliability for test results of test organization. In order to apply to the field of railway, brake disk lining as one of the railway components has been selected and the comparison test is executed for the purpose of guaranteeing the reciprocal reliability for the test result of both organizations and enlarging the substantial technique exchange of both nations by the standard establishment with test procedures and test programs from now on.

• International Journal of Railway
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• v.4 no.4
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• pp.109-115
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• 2011

An analysis and design method for reducing aerodynamic noise in high-speed trains based on biomimetics of noiseless flight of owl is proposed. Five factors related to the morphology of the flight feather have been selected, and the candidate optimal shape of the flight feather is determined. The turbulent flow field analysis demonstrates that the optimal shape leads to diminished vortex formation by causing separation of the flow as well as allowing the fluid to climb up along the surface of the flight feather. To determine the effect of scaling of the owl's flight feather on the noise reduction, a two-fold and a four-fold scaled up model of the feather are constructed, and the numerical simulations are carried out to obtain the aerodynamic noise levels for each scale. Original model is found to reduce the noise level by 10 dBA, while two-fold increase in length dimensions reduces the noise by 12 dBA. Validation of numerical solution using wind tunnel experimental measurements is presented as well.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.371-377
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• 2008

As a railway is receiving attention as an environment-friendly transportation mode, many high speed, inter-city and urban railway are constructed and remodeled in the world. With this trend, railway RAMS was included in the international standard IEC 62278 in 2002. RAMS activity in domestic market is also increased with this international trend. However, IEC 62278 does not describe the methodology of substantial contents like how reliability target is set although it can be used as an overall guideline when RAMS requirements are included in the purchase specification. That is because RAMS requirements should be set with the specific railway condition. It is required to fully understand the meaning of railway RAMS parameters and apply those correspond to the specific railway system and environment condition especially when a quantitative RAMS requirement is set. In this study, the meaning and characteristics of RAMS parameters applicable to the development of quantitative RAMS requirement of rolling stock is described. And the basic concept of RAMS and the definition of failure that IEC 62278 describes is modified and suggested in order to make more suitable to the development of quantitative RAMS requirement.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.761-772
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• 2009

The introduction of KTX (Korea Train eXpress) provided passengers with a much faster mode of transport, and KTX has become a model railway system. Express railway stations are emphasized as public transit transfer centers, but their service evaluations were not performed appropriately so far. It is possible to know the level of service by developing valuation criteria for their evaluations. The evaluation of transfer centers mainly consists of two parts; connective service with other travel m odes, and transfer service inside transfer stations. Connection is defined as the inter-connection of multi-transportation vehicles, and transfer means that a passenger changes his travel mode to another. Such connective service and transfer service are evaluated by the level of service in terms of transfer facilities, the appropriateness of station layout and the quality of information throughout the facilities. We developed the service evaluation indicators of connective facilities and referred to the indicators of transfer facilities. We examined the 7 stations in Korea that are currently in operation and standardized the methodology of the evaluation process by applying the indicators suggested in this study.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.229-233
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• 2005

This paper explains development status of the Korean tilting train. The Korean Tilting Train eXpress (TTX) project has been carried out to develop all the core technologies related to tilting train and infra-technology to provide high speed inter-city service with the speed of 180 km/h as well as maintenance-free technology for conventional railway system. The TTX project is under 5th stage. In this stage, manufacturing and combination test for the main components are being conducted. By the end of next year, assembly of TTX will be completed.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.483-488
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• 2004

The inter-laboratory comparison test which is demanded on the authorized test of ISO/IEC 17025 is the program to guarantee the confidence of test result. This paper, as a part of the inter-laboratory comparison test between South Korea and China, is refered to the characteristic of friction coefficient of disk brake lining for rolling stock according to disk type. Brake tests were carried out under constant brake force and operating sequence by using dynamo-tester according to disk and disk lining types. To establishing the confidence of test result, we calculated A type uncertainty about friction coefficient and investigated the factors about the variation of friction coefficient.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.52-57
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• 2003

This study suggests several ways to improve the railroad facilities in the urban areas so as to maintain the urban railroad facilities and minimize their adverse impact on the roads around the facilities. Environmental problems such as noise and vibration can be minimized by constructing soundproofing walls and improving railway and train systems. To reduce the traffic congestion at the railroad crossings, current at-grade crossings should be changed to separated crossings. Moreover, the criteria by where railroad crossings are located should be revised. In the long term, the land use development for the railroad station and the surrounding areas needs to be changed. Several case studies of Japan's and France's major cities show the potential of successfully integrating the development of railroad facilities and their surrounding areas. In addition, there is a need to .consider institutional aspects, to improve the railroad facilities in the urban areas and to allow the integrated development of the railroad facilities and the surrounding areas.

• International Journal of Railway
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• v.4 no.3
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• pp.74-79
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• 2011

Recent years have witnessed speed up of moving vehicles such as high-speed of trains. Increase in speed entails concomitant increase in turbulent air flow which contributes toward increased aerodynamic noise. The proposed method for aerodynamic noise reduction is based on a biomimetic design of owl feather. The five morphological parameters of the owl feather are extracted from close observation, and simulation cases are constructed by applying design of experiments methodology. Swirling strength for each case is obtained through steady-state CFD analysis, and key morphological parameters that affect the turbulence are identified. Large eddy simulations (LES) are then performed on selected cases to predict the air turbulence. Different cases show varying vortex distributions which are expected to lead to varying aerodynamic noise levels.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.283-290
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• 1999

Recently, the ${\mu}$-processor based-controlled systems instead of conventional relays circuitry are widely used to industrial applications, and also those technology is available to railway signalings which are safety-critical systems. However, the safety and reliability of software for those systems are harder to demonstrate than in traditional relays circuitry because the faults or errors can not be analyzed and predicted to those systems. So, the safety problems are crucial more and more in ${\mu}$-processor based-controlled system. In this paper, the Grafcet language, the graphical and mathematical form, is used to obtain the high-level safety and reliability of software control logic. The general description for Grafcet notation are provided. And some partial of interlocking logic are formally modeled and simulated by Grafcet language and graphical windows.