• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.190-195
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• 2017

This paper proposes a method to detect rail broken through impedance measurement. In general, broken rails are detected in real time using the track circuit, but the proposed method not only detects the broken rails but also estimates positions of broken areas by measuring the rail impedance. To electrically insulate one side of the rail, parallel resonance is made by adding a capacitor; then, the impedance of the other rail is measured. If the measured impedance has an inductive value, there is no broken area of rail. However if the measured impedance has a capacitive value, the rail is broken. The proposed method is modeled using a transmission line; it is shown that the modeling can estimate the position of the broken rail according to the impedance value. The rail impedance is measured by the proposed method for a 60m simple rail model, and it is verified that the presence of a broken rail changes the rail impedance.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.750-755
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• 2004

This paper deals with the domestic status of rail gap and criteria of the maximum allowable rail gap for the broken rail. Parameteric studies about the maximum allowable rail gap were accomplished by the zimmermann model. The dynamic behavior of broken rail not to be explained by the existing theory was looked into. When a train is travelling along rail gap for the broken rail, dynamic behaviors of rail system and train are abruptly changed. And the opinion about a permission criteria of the rail gab was presented.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.1-7
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• 2013

Train accidents can be directly connected to fatal accidents-collision, derailment, Fire, railway crossing accidents-resulting in tremendous human casualties. First of all, the railway derailment is not only related to most of railway accidents but also it can lead to much more catastrophic accompanying train overtured than other factors. Therefore, it is most important factor to ensure railway safety. some foreign countries have applied to the detector machines(e.g., ultrasonic detector car, sleep mode, current detector, optical sensing, optical fiber). Since it was developed in order to prevent train from being derailed. In korea, the existing track method has been used to monitor rail condition using track circuit. However, we found out it impossible for Communication Based Train Control system(CBTC), recent technology to detect rail condition using balise(data transmission devices) without no track circuit. For this reason, it is needed instantly to develop real-time monitoring system used to detect broken rails. Firstly, this paper presents domestic and international statues analysis of rail breaks technology. Secondly, the composition and the characteristics of the real-time monitoring system. Finally, the evidence that this system could assumed the location and type of broken rails was proved by the experiment of prototype and operation line tests. We concluded that this system can detect rail break section in which error span exist within${\pm}1m$.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2082-2089
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• 2011

This study is examination of application on site for performance and stability of real-time broken rail detection equipment development system about connection, welded part occurring data errors of broken rail monitoring system. As a result of analysis about data collected in Seoul Metro No.2 Subway from Mar. 2010 to Jan. 2011, we found it is possible to detect crack location(Thermit welding) within the margin of error of ${\pm}1m$ accurately as the first attenuation was -1.2dB and the second was -1.3dB.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.345-355
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• 2007

During winter, the CWR (continuous welded rail) may be broken when a temperature drop below the neutral level changes the axial force, causing tensile fracture and creating a rail gap. The passage of a train on a rail with an open gap may lead to very costly derailments. In this paper, the use of a track-and-train-coupled model whose rail has an open gap is proposed for dynamic interaction analysis. Linear track and train systems were coupled in this study by a nonlinear Herzian contact spring, and the complete system matrices of the total track-train system were constructed. Moreover, the interaction phenomenon considering the presence of an open gap in the rail was toughly defined by assigning the irregularity functions between the two sides of the gap. Time history analysis, which has an iteration scheme such as the Newmark-$\beta$ method (based on the Modified Newton-Raphson methods), was conducted to solve the nonlinear equation. .Finally, numerical studies were conducted to assess the effect of the various parameters of the system when applied to various speeds, open-gap sizes, and support stiffnesses of the rail.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1399-1406
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• 2011

As a result of the examination analyzed loop type of Detecting the Broken Rail Monitoring System as a part of prevention of train derailment, installed in the Seoul Metro No. 2 subway line 98.51m section which is Samsung to Seolleung, we found that it is possible to detect crack location(Thermit welding: 48.18m) within the margin of error of ${\pm}1m$ accurately As analysis of the first day, third day, fifty day, and seventh day periodically, we found that Fresnel reflection happened where the crack location 48.18m. However other 3 branches show loss by bending of optical cable(spread reflection from the outside impact).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.719-726
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• 2006

The use of CWR track not only reduces the track maintenance cost, but increase the life cycle of track components. Therefore, the use of the CWR track has increased consistently in the worldwide. As the use of CWR increases in track structures, derailing disasters associating with track buckling also increase in great numbers due to high compressive thermal stress in the summer. Among many CWR parameters, the influence of the sectional properties of the rail was investigated on the stability of CWR track in this study. Also, the sensitivity of the broken fastener and the stiffness of the fastener system such as the translational and rotational stiffness was investigated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.895-904
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• 2008

CWR (Continuous Welded Rail) may be broken when a temperature drop below the neutral temperature changes in axial force, causing tensile fracture and rail gap, in winter. Rail-breaks may lead to the damage of the rail and wheel by dynamic load, and the reduction of running safety if not detected before the passage of a train. In this study, the track and train coupled model with open gap for dynamic interaction analysis, is proposed. Linear track and train systems is coupled by the nonlinear Herzian contact spring and the complete system matrices of total track-train system is constructed. And the interaction phenomenon considering open gap, was defined by assigning the irregularity functions between the two sides of a gap. Time history analysis, which have an iteration scheme such as $Newmark-{\beta}$ method based on Modified Newton-Raphson methods, was performed to solve the nonlinear equation. Finally, numerical studies are performed to assess the effect of various parameters of system, apply to various speeds, open gap size and the support stiffness of rail.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.984-988
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• 2010

In Korea, the next generation high-speed train, whose target is maximum speed of 400km/h and operating speed of 370km/h, has been developed since 2007. In this paper, the safety of the next generation high-speed train is compared UIC 518OR under the malfunctioning situation of the suspension system. The bogie of the next generation high-speed train has two suspensions. Two different vehicle models of the next generation high-speed train are created by using VAMPIRE and ADAMS/Rail, which are specialized to design railway vehicle. And Those models are showed same dynamic properties. First of all, the sensitivity analysis of ModelCenter is performed using model of VAMPIRE. One suspension element which has significant effects on the safety are selected by result of the sensitivity analysis. And then, the dynamic analysis when the suspension element is broken is performed using ADAMS/Rail. The 30km track between Pungsegyo and Biryong tunnel in Gyeongbu High-speed Line was used at the dynamic analysis. The estimated value is found by using the normal method of UIC 518OR. The estimated values on the normal/fault state and the limit values of UIC 518OR are compared. Finally, the safety of the next generation high-speed train is verified.

• Journal of the Korean Society for Railway
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• v.8 no.1
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• pp.63-81
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• 2005

In this Paper, Ⅰ illustrate the continuity and severance of Korean railroad. The Korean railroad has been running for 105 years now since it started operation in 1899. Between 1905 and 1945, Japan's imperial government ruled Korea including operations of the railroad. After Korea restored its sovereignty, Korean nationals managed the Korean railroad with our own ability and strategies. At present, we can examine the effect of railroad in perspective of continuity and severance respectively. For one thing, the concept of continuity is described as influence or railroad still remains. For another, the severance shows facts and phenomena that are broken off. I have come up with some facts that are involved with continuity. For example, infrastructure and the formation of cities and land spaces are connected with the sequence. Futhermore, the railroad has made a huge dent in modernization and expedition of movement. In the course of tracing down the facts, I classified the concept of severance : the separation of South and North Korea, drastic changes in transport policy, operations and characteristics. Finally technology has brought about a major breakthrough with the development of Koran high speed rail.