• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.177-185
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• 2013

A new theoretical derailment coefficient model of wheel-climb derailment is proposed to consider the influence of wheel unloading. The derailment coefficient model is based on the theoretical derailment model of a wheelset that was developed to predict the derailment induced by train collisions. Presently, in domestic derailment regulations, a derailment coefficient of 0.8 is allowable using Nadal's formula, which is for a flange angle of $60^{\circ}$ and a friction coefficient of 0.3. However, theoretical studies focusing on different flange angles to justify the derailment coefficient of 0.8 have not been conducted. Therefore, this study theoretically explains a derailment coefficient of 0.8 using the proposed derailment coefficient model. Furthermore, wheel unloading of up to 50% is accepted without a clear basis. Accordingly, the correlation between a wheel unloading of 50% and a derailment coefficient of 0.8 is confirmed by using the proposed derailment coefficient model. Finally, the validity of the proposed derailment coefficient model is demonstrated through dynamic simulations.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.857-862
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• 2002

The bogie, when run on the twist track develops the wheel off-loading factor. This will be comfirmed by testing under different loading conditions and air springs inflated and deflated in all conditions. Under the most extreme twist track condition, EMU (Electrical Multiple Unit) shall not over the wheel off-loading requirement 60% defined on UIC / ORE report. This paper describes the wheel off-loading test procedure according to UIC / ORE and test result of DMRC EMU of INDIA carried out to find out to meet the requirement defined in UIC / ORE.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.101-101
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• 2003

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.492-498
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• 2007

For the running safety assessment of Saemaul train passing through curves, an analysis model for multibody system has been developed. By using this model and ADAMS/Rail, sensitivity analyses depending on the variation of parameters related to the derailment coefficients have been conducted. At low speed, the derailment coefficient and the unload ratio of right wheel showed higher than left wheel, while those of left wheel showed higher than right wheel at high speed. According to decrease of curve radius, the derailment coefficient and the unload ratio were increased. When the length of transition curve was increased, the derailment coefficient was increased but there was no change on the unload ratio. According to the increase of cant, the derailment coefficient and the unload rate were increased.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.320-328
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• 2017

In order to analyze the influence on derailment safety according to the aging of primary rubber springs widely applied to railway vehicles, characteristic tests were carried out on aged primary rubber spring samples. To analyze the effect of primary rubber spring aging on derailment safety, a vehicle dynamic analysis was carried out. The results of the vertical characteristics test for the rubber spring specimens with 17 years of service life revealed that the displacement restoration function was degraded due to rubber aging and the spring stiffness significantly increased. The results of the running dynamic analysis simulating the twist track running in accordance with the EN14363 standard, compared with the normal vehicle model (Case 1), showed that the derailment coefficient and the wheel unloading of the vehicle model (Case 2) using the aging primary spring characteristic increased, and the derailment safety was degraded. IN particular, it was found that the derailment safety due to the reduction of the wheel load is weak in the transient section where a steep slope change occurs.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.234-239
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• 2011

Installing the temporary bridge after excavating the railway requires installing movable cross beam, but as it doesn't requires isolating the catenary or cutting the rail, it's applicable to double-track with frequent operation. In this study, a displacement meter was placed on temporary bridge to monitor the displacement pattern in curve section (R400) completed using temporary bridge method, and wheel load, lateral pressure and derailment coefficient were measured to evaluate the load imposed on track and the stability in curve section (R400) for quantitative evaluation of training running safety. As a result of the measurement, when trains passing over a temporary bridge, the maximum value of Wheel load and Lateral Force is analyzed as the 51% and 81% of standard level according to foreign country's performance tests, There is no trouble with stability analysis in Wheel load and Lateral Force occurring. Additionally, Wheel load and Lateral Force considered as the safety standard are tested 49% of limiting value regardless of trains, which the norm value quite well, there is no problem with train running.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.176-176
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• 2004

21세기 고속철도시대에 진입하면서 차량고속화에 수반하여 주행안전성 면에서 빼놓을 수 없는 문제로 가장 중요한 탈선의 현상이 있다. 철도에 있어서 탈선은 대형사고로 직결되기 때문에 결코 쉽게 간과할 수 없는 부분이며, 철도가 다른 교통수단에 비해 상대적인 장점으로 내세울 수 있는 안전성을 확보하기 위하여 반드시 차륜과 레일 사이에서 발생하는 상호 작용력을 측정하여 탈선가능성을 평가하여야만 한다.(중략)

• Journal of the Korean Society for Railway
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• v.4 no.4
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• pp.131-137
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• 2001

The dynamic behavior of high speed train is very important because of its safety and passengers' ride comfort. The railway vehicle is composed of many suspension components, such as 1st springs, 1st dampers, 2nd springs and 2nd dampers, that have an influence on the dynamic characteristics of high speed train. Also, the wheel/rail shapes and the track geometry affect the dynamic behavior of high speed train. This paper reviews the dynamic behavior of KHST in the KTX test line. The VAMPIRE program is used for this simulation. The simulation results are within the limits of safety criteria. Thus the KHST can operate safely at 350 km/h in the KTX test line.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.701-708
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• 2007

A tilting train, which was developed to run the curve section without reducing the speed and compromising the riding quality, can improve the speed so as to reduce the travel time, compared to the existing trains. Then the force generated by the train operation to the track is in proportion to train operation speed, which means the track shall bear the increased force as much as the increase in train operation speed. Particularly, wheel load and lateral wheel load generated by train operation and distributed to the rail tend to cause the track to suffer the strain and furthermore the severe disaster such as derailment. To deal with such problem and ensure the train will run safety and stably, the tolerance in wheel load change, lateral wheel load and derailment coefficient was determined for quantitative evaluation of the train operation stability. In this study, derailment coefficient of inner and outer rail at existing curve section of tilting train was determined to evaluate the curve radius, possibility of acceleration and the need of rail improvement, which was then compared with the existing traditional train and high speed train. Conducting the quantitative evaluation of dynamic wheel load and lateral wheel load of each train, which was based on field survey, derailment coefficient and static & dynamic wheel load change, which serve the evaluation criteria of train operation stability, were determined for comparison with the standards, thereby analyzing the stability of the tilting train.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.485-488
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• 2011

본 연구에서는 경부고속철도의 콘크리트궤도에서 열차주행안전측면에서 관리해야할 레일패드강성의 상한값을 차량 및 궤도의 동특성과 운영환경을 고려하여 결정하는 방법을 제시하였다. 차량과궤도의 상호작용의 해석의 중요 입력파라메타인 궤도틀림과 관련하여 프랑스 및 독일에서 제시한 궤도틀림 PSD(Power Spectral Density)와 경부 1단계구간 콘크리트궤도에서 계측한 궤도틀림 자료를 통하여 얻은 PSD를 기초로 하여 넓은 범위의 주파수영역에서 적용할 수 있는 콘크리트궤도의 궤도틀림 PSD를 제시하였다. 제시된 PSD 기준모델을 사용하여 시간영역에서의 궤도틀림 입력을 Random Generation을 통하여 구한 후 개발된 차량-궤도 상호작용해석 기법을 사용하여 레일패드에 따른 윤중감소율을 산정하였다. 산정된 윤중감소율에 대하여 국내 철도차량 안전기준에 관한 규칙의 탈선계수 규정을 적용하여 주행안전측면에서 허용할 수 있는 레일패드강성의 상한값을 제시하였다.