• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.579-590
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• 2012

Weight reduction of a railway axle, which is one of heaviest parts in an urban railway vehicle, is discussed in this paper. A wheelset of a railway vehicle is very important with regard to railway safety, and its structural strength should always be considered when attempting to reduce the railway axle weight. In this work, the weight of the axles of a trailer bogie and a motor bogie of the Korean EMU was reduced by replacing solid axles with hollow axles. On the basis of the EN standard for railway axle design, the strength of existing solid axles was analyzed and the required bore size of a hollow axle was determined. It is shown that the weight of the concurrent axle of the Korean EMU can be reduced by up to 20% with a very small decrease in the structural strength. Finite element analyses were also carried out to verify the design result for lightweight hollow axles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.609-617
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• 2017

Railways are one of the safest and most important transportation systems in the world. On the other hand, due to the increasing complexity of the railway system and the running distance of rail vehicles, railway accidents occur continuously every year. In particular, in the case of high-speed trains and freight trains, if the function of the axle bearing is lost due to abnormal overheating of the axle box bearing, the load on the axle becomes uneven. Therefore, abnormal overheating in the train axle box bearings can cause serious accidents or derailments. For this purpose, a Hot Box Detector (HBD) was installed in the track side of a high speed line to detect abnormal overheating. This paper proposes an EWMA technique-based axle temperature monitoring method to detect abnormal overheating quickly and efficiently. A statistical design of the proposed method was also performed. The proposed method has better performance compared to the current method in the case of abnormal overheating and the performance is improved by approximately 170% at the maximum.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.116-120
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• 2010

The wheelset, an assembly of wheel and axle, is one of important parts in railway bogie, directly related with the running safety of railway rolling stock. In this investigation, the tensile failure behavior of railway axle materials was investigated. The tensile coupons were prepared from the actual rolling stock parts, which were operated over 20 years. The tensile testing was performed according to the KS guideline. During tensile testing, an infrared camera was employed to monitor temperature changes in specimen as well as demonstrate temperature contour in terms of infrared thermographic images. The thermographic images of tensile specimens showed comparable results with mechanical behavior of tensile materials. In this paper, the failure mode and behavior of railway axle materials were provided with the aid of infrared thermography technique.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1581-1582
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• 2015

최근 많은 승객을 수공하는 대중 교통시스템의 안전에 대한 중요성이 더욱 대두되고 있으며, 고속화된 철도차량 또한 이를 피해갈 수 없다. 현재 철도차량의 사고 방지를 위해 많은 연구가 이루어 지고 있으며, 차량기지의 검수설비 및 검수시스템이 자동화되어 많이 발전되었다. 그 중 차축 초음파 탐상은 각 차량기지에 설치된 A-Scan 초음파 방식과 Phased Array 초음파 방식의 두가지 방식의 장비를 이용하여 차축 초음파 탐상이 이루어 지고 있다. 본 논문에서는 초음파 방식 중 철도차량 차축 결함 검출을 위한 A-Scan 탐상 방식과 Phased Array 탐상방식에 대하여 비교 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5534-5540
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• 2015

This In the railway signaling system, applications of axle counter in addition to track circuit goes on increasing for detecting train position. Consequently, this paper compares sensor methods of axle counter with between geo-magnetism method and proximity sensor method. And it presents differences and results, to improve reliabilities of train detection and axle counting. Also, this article presents an applied result which is based on field experience, with regard to installation, considering attachment condition of sensor part for accurate axle counting. This study acquires expandability that is able to perform not only axle counting function but also various other functions (direction detection of train, speed detection of train, and so on). It was a result of a change of design in order to judge phase difference of sensors, to improve reliability of axle counting. Furthermore, it does not subordinate to characteristics (type, weight of train). And it is confirmed that the omission of axle counting was not occurred in 350km/h. This was the result of Lab test after the construction of transfer equipment of trial axle and Test Bed for axle counting. Both of them are self-productions. Through this, it prepares foundation which is able to apply not only to train detection but also to speed of passing trains, formation number of trains, detector locking condition - when the train passes the section of switch point, and level crossing devices. Furthermore, it would be judged to contribute safety train operation if proximity sensor method applies to the whole railway signaling system from now on.

• Railway Journal
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• v.15 no.4
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• pp.21-26
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• 2012

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6214-6220
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• 2015

A track circuit has used stably more than 100 years for detecting train position, but solution of track circuit sort circuit incapacity due to a rust is necessary for side line in station yard, coast line and level crossing for conventional line in rural line. Domestically, Axle Counter System(ACS) has partially used for Hot Box System for high speed line and turnout for CBTC system. In contrast, most of countries has used ACS not only trunk line but also rural line and its application has increased for metro, electric car and industrial railway. In this paper, we has verified the operating status of ACS which installed with existing track circuit through log analsis to implement pilot application in mail track and turnout in station yard. And interface test with interlocking system has conducted at Obong shunting yard, as well as Cheongju station and has analyzed test result. Based on a test result, we made fail safe design, manufacturing skill and established system requirement specification for the smooth operation and maintenance.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.98-105
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• 2008

철도차량 차축의 초음파 탐상은 기존 펄스-에코방식을 사용하여 A-Stan으로 영상화하여 결함평가가 이루어 졌다. 하지만 이 방법은 작업자의 판단에 의존하므로 신뢰성이 멀어졌다. 위상배열 초음파 탐상 검사는 단일 탐촉자에 여러개의 진동자를 배열하여 여러 각도에서 탐상이 가능하므로 차축처럼 종류 및 모양이 다양한 구조물의 탐상에 효과적이다. 또한 C-Scan방식으로 영상화 하므로써 작업자가 결함을 판단하는데 있어서 객관적인 평가방법이다. 이 논문에서는 위상배열 초음파 탐상 검사에 대하여 설명하고 차축결함평가를 위한 자동화된 설비의 논리설계를 분석하고 그 실험의 방법과 결과론 고찰하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1257-1258
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• 2012

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5039-5044
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• 2015

In this study, we evaluated corrosion behavior of a common rolling stock axle material, RSA1, in seawater. 3-electrode electrochemical cell experiment was conducted using artificial sea water, fabricated according to ASTM-D1141 set by American Society for Testing and Materials, where the corrosion current density and corrosion rate were determined to be $18.3{\mu}A/cm2$ and 0.217 mm/yr, respectively, by employing potentiodynamic test method and impedance spectroscopy method. Considering the fact that life time of railway car is ~25 years, the expected corrosion layer depth is 5mm. Constant-current corrosion test was conducted to accelerate the corrosion process, to reach corrosion periods of 1,3 and 4 years based on Faraday's law, followed by tension tests where the reduced specimen gauge cross-section was re-measured for stress calculation. While no apparent corrosion-related changes in mechanical properties were observed in the elastic regime, the reduction in ductility of the material was found to be increased as the corrosion period increased. The results of this study are expected to be basic corrosion data for the design of rolling stock axles, which will be operated in the sea water environment.