• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06b
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• pp.7-13
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• 1995

현재 교통인구 비중에 큰 비중을 차지하고 있는 철도 차량은 기술의 발전으로 인한 고속화에 성공하여 300km/h대의 속도를 달성하기에 이르렀다. 열차가 고속화됨으로 인하여 열차 주행시 운동에너지가 더욱 커졌고 이를 소산하기 위한 제동 역시 더욱 중요하게 되었다. 열차의 제동시 중요한 점은 wheel의 skidding을 방지함으로 wheel의 편마멸을 줄이는 것이며 이를 위해선 제동장치의 설계시 wheel과 rail간의 점착현상의 이해가 필수적이다. 제동력이 점착력보다 클 경우는 skidding이 발생하며 제동력이 점착력보다 작은 경우는 충분한 제덩을 하지 못한다는 것을 의미한다. 그러므로 열차의 제동장치를 설계함에 있어서 점착계수는 필수적인 요소가 되었으며 미국, 일본, 독일 등의 선진 각국에서는 점착계수를 측정하여 그 특성을 파악하려는 실험이 실험실 및 실차 차원에서 많이 행하여졌다. 각각 다른 접척조건, 속도 등에 따른 실험이 진행되어 왔으나 각 연구의 결과는 조금씩 다른 결향을 나타내었고, 점착현상에 관한 물리적인 설명은 못하고 있는 실정이다. 본 연구에서는 wheel과 rail의 접촉인 경우에 있어 점착현상의 변화를 속도, 하중, 접촉조건에 따른다고 보고 점착현상의 특성을 각각 sliding, pure rolling실험을 통해 파악하고 기타 참고문헌에서 발표된 점착계수와 비교하여 물리적으로 이해하고자 하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1786_1787
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• 2009

철도는 안전성, 신뢰성, 에너지절약 등 여러 가지 측면에서 다른 교통수단과 비교하여 여러 장점을 가지고 있기 때문에 많은 나라에서 각광을 받아 왔다. 최근 들어서는 고속열차 뿐만 아니라 기존선을 고속으로 주행하기 위한 연구도 활발하게 수행되고 있다. 이 논문에서는 독자 기술로 개발된 한국형 틸팅열차에 탑재되어 있는 틸팅시스템에 대한 성능평가를 수행한 결과에 대하여 살펴보았다.

• Journal of the Korean Society for Railway
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• v.9 no.5 s.36
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• pp.606-611
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• 2006

This paper presents a procedure and an analysis method to evaluate reliability of the Korea high-speed train. The rolling stock system is divided into 6 sub-systems and each subsystem is classified into sub-assemblies. Functional analysis has been conducted to draw reliability block diagrams for the sub-systems. First, failure rates has been calculated for each sub-assembly from the failure data obtained during commissioning tests. Then a reliability block diagram is used to evaluate the MKBF(Mean Kilometers Before Failure) of the sub-systems. Activities to increase reliability have been carried out throughout the test runs and analysis results show that the reliability of the rolling stock system is gradually growing in time.

• Journal of KSNVE
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• v.9 no.6
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• pp.1106-1115
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• 1999

This paper sums up the study of the soundproof facilities (noise barriers) to be placed on the test track section within the Seoul-Pusan H.S.T. project. The objective of this study is to determine optimum design of soundproof including height, length, location, sound absorbing materials for test track(chonan-taejon). This paper shows the model to design the shape and materials of noise barrier for high speed trains(TGV, ICE, ect). The design of soundproof facilities is to be conducted by MITHRA for the prediction of noise impact of the TGV and for optimising noise barriers in order to reduce the noise generated by high speed trains. A number of computer simulations are carried out in order to determine the specification of noise barrier on test track.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3672-3679
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• 2015

The heat generated by electrical components during train operation was estimated by measuring the wall temperature in a locomotive, as well as the temperature and speed of the air entering from the outside and then returning to the outside. The temperatures of the electrical components and wall surface in a high-speed train were measured using an infrared camera. The heat generated by the electrical components was exhausted to the outside through a duct installed on the ceiling of the high-speed train. Thus, the temperature and speed of this exhaust air were measured, as well as those of the air entering the locomotive from the outside. The temperatures at the surfaces of the electrical components and walls in the locomotive were also measured using an attachment-type temperature sensor. In addition, the measurement results were applied to analyze how the heat characteristics of the electrical components were affected by the train operation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.2
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• pp.121-128
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• 2020

The purpose of this study is to investigate the distribution patterns of displacement and acceleration fields in a nonlinear soil ground based on the interaction of high-speed train, wheel, rail, and ground. For this purpose, a high-speed train in motion was modeled as the actual wheel, and the vertical contact of wheel and rail and the lateral contact, caused by meandering motion, were simulated; this simulation was based on the moving mass analysis. The soil ground part was given the nonlinear behavior of the upper ground part by using the modified the Drucker-Prager model, and the changes in displacement and acceleration were compared with the behavior of the elastic and inelastic grounds. Using this analysis, the displacement and acceleration ranges close to the actual ground behavior were addressed. Additionally, the von-Mises stress and equivalent plastic strain at the ground were examined. Further, the equivalent plastic and total volumetric strains at each failure surface were examined. The variation in stresses, such as vertical stress, transverse pressure, and longitudinal restraint pressure of wheel-rail contact, with the time history was investigated using moving mass. In the case of nonlinear ground model, the displacement difference obtained based on the train travel is not large when compared to that of the elastic ground model, while the acceleration is caused to generate a large decrease.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.561-567
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• 2018

This study was carried out to improve the ride quality of high-speed electric multiple unit. Through dynamic analysis of the HEMU-430X, the range of the equivalent conicity with a critical speed of 300 km/h was between 0.05 and 0.25. The initial adopted wheel profile of HEMU-430X was S1002. The equivalent conicity of S1002 with the mileage of more than 40,000 km was about 0.033 and it was confirmed that XP55 is more suitable for stable operation because XP55 has the equivalent conicity of over 0.061. In order to improve ride quality of high-speed electric multiple unit, the change of installation angle of the yaw damper was suggested from $7.35^{\circ}$ to $0^{\circ}$. From sensitivity analysis and optimization, the air spring lateral and vertical stiffness was suggested to be reduced by 30% and the secondary vertical and lateral damper damping coefficient was increased by 50%. By applying this, it was expected that the car body acceleration could be improved by about 20% on average. The HEMU-430X's yaw damper installation angle was changed to $0^{\circ}$ and the damping coefficient of the lateral damper was increased by 30%. When the test run was carried out at the speed of 300 km/h on the Kyungbu high-speed line, the vehicle lateral acceleration had improved by 34.3%. The effect of additional improvement measures proposed in this paper will be tested in the on track test. The riding quality improvement process used in this study can be used to solve ride quality problems that can occur in commercial operation of high-speed electric multiple unit in the future.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.660-664
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• 2007

Korea High-speed Railway (HSR-350x) was developed by Korean government, several institutes, and related companies. HSR-350x was investigated its performance and tested at the high speed line. In 2004 December, HSR-350x was run over 350km/h and proved its running performance. And Korean Train Express (KTX) served the commercial traffic for 4 years. These high speed railways have 12 motors to transfer the traction effort or the braking force. To obtain the load of the transfer shaft, it is necessary to measure the transferred torque of the shaft. In this paper, authors propose the construction the measurement system fur monitoring the force transferred to the train from the motor The system was installed to the tripod shaft which is located between the reduction gears and it measures the mechanical load directly.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.396-404
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• 2009

With developing the next generation high speed railway, there need to be plans to make sure of running safety though researchs on the crack and break of rail by rolling contact fatigue. Therefore, this study performed the parametric analysis effecting on the fatigue life of rail using simplified equations. It analyzed the internal stress of rail according to the track quality, train velocity, wheel radius, track stiffness, sleeper space, wheel load. For the more, via the finite element method, it analyzed shear force on the rail head which could be changed by the early length of crack, angle of crack and temperature. As a result, this study continued the main parameter effecting on the fatigue life of rail.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.66-72
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• 2019

To improve ride quality and running stability of high speed train(HST), it is important that connection between coaches adopts the articulated bogies by using a gangway ring, unlike the conventional independent bogies assembled with car bodies. Although the gangway ring should be ensured absolute safety against passenger movement between coaches during train operation, there is still a lack of quantitative durability criteria of that. Therefore, in order to improve the passenger safety of HST, it is important to study the test requirements on durability evaluation for the ring. In this study, seven mixed loading cases were derived from the triaxial loading(vertical/lateral/longitudinal) modes. The safety factor of each component is at least 2.4 or more from the results of the finite element analysis. In addition, fatigue safety was evaluated through durability analysis from the viewpoint of strain-life design. Durability tests for the gangway ring carried out a total of 10 million cycles in 4 phases load conditions. After the durability test, the defect of each component was investigated using nondestructive testing techniques.