• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.252-256
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• 2003

Smart materials can adapt to changes of environment like living organs in nature such that they can maximize the performance and minimize the maintenance expense of engineering systems. Such materials have been paid attention ten years ago and applied in the area of industry, aerospace, transportation and civil structures. This paper summarizes smart material technology and shows some application examples in railway vehicles. Also, its future of smart material technology in railway vehicle technology is envisaged based on its possibility and practical aspect.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.47-53
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• 2010

A stabilizer link connects the stabilizer bar to the lower arm of the suspension. When a vehicle is turning, lateral forces from the tire are transmitted through the stabilizer link into the stabilizer bar. The stabilizer bar will twist, thus adding rigidity to the vehicle body. In this study, the stabilizer link body was manufactured by using composite material with POM-GF25%. Therefore, the strength evaluation of stability link body with composite material carried out from tensile, wear and fatigue test. The tensile strength between the stability link body with composite material and the rod with knurling was the largest of four types of rod. In Analyzing materials property using optical sensing technique of stabilizer link for automobile parts, its has been identified the safety.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.807-819
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• 2002

The air spring is used in secondary suspension system for railway vehicle to reduce and absorb the vibration and noise. In this paper, the characteristics and durability test was conducted in laboratory by using servo hydraulic fatigue testing system to evaluate the reliability. And to guarantee the adaptation of this air spring, the ride comfort and air pressure variation were measured in train test. The experimental results show that the characteristics and durability of domestic development productions are obtained the good results and the stiffness of the air spring which had become 6 year over increased. Also, the dynamic characteristics of domestic and existing product agree well the results obtained.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.626-633
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• 2000

An air spring which is a part of the railroad vehicle suspension system is used to reduce and absorb the vibration and the noise. Main components of the air spying are a cord reinforced rubber bellows, a upper plate, a lower plate and a stopper rubber spring. The characteristics of the air spring which are the load capacity, the vertical and the horizontal stiffness are depended on the configuration of rubber bellows, the angle of cord and the mechanical properties of cord. The computer simulation using commercial finite element analysis codes are executed to predict and evaluate the load capacity and the stiffness. The appropriate shape and cord angle of the air suing are selected to adjust the required performance of the air spring. Several samples of the air spring are manufectured and experimented. It is shown that the results by computer simulation are in close agreement with the test results.

• International Journal of Railway
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• v.1 no.3
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• pp.122-127
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• 2008

Rubber components are widely used in many application such as vibration isolators, damping, ride quality. Rubber spring is used in primary suspension system for railway vehicle. Characteristics and useful life prediction of rubber spring was very important in design procedure to assure the safety and reliability. Non-linear properties of rubber material which are described as strain energy function are important parameter to design and evaluate of rubber spring. These are determined by physical tests which are uniaxial tension, equi-biaxial tension and pure shear test. The computer simulation was executed to predict and evaluate the load capacity and stiffness for rubber spring. In order to investigate the useful life, the acceleration test were carried out. Acceleration test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful life prediction for rubber spring were proposed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.43-49
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• 2006

To design railway vehicles to ensure comfortable running, ride comfort of human exposed on vibrating carbody should be considered. Also, to improve ride comfort for passenger coach, many factors should be analysed and evaluated. There are many factors as suspension characteristics of railway vehicle, track characteristics to run etc. In this paper, passenger coach sujected to test on specific routine were evaluated using test results. Test routine were divided by 13 sections to analyse more detail. And the characteristics of every section were analysed distributions of radius curves, tunnel and bridge which could give impact to ride comfort. The evaluation of ride comfort were accomplished by UIC and ISO methods.

• Journal of the KSME
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• v.33 no.10
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• pp.871-883
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• 1993

차량의 승차감 및 조안 성능을 결정하는 중요한 인자인 현가장치(Supension System) 설계의 최적화를 기하며 실차육성기간을 줄이고 설계 업무의 효율성을 높이기 위하여 각종 차량 특성 인자의 수치화를 통해 여러 가지 해석을 수행하게 된다. 이러한 해석 과정으로는 크게 현가장 치의 기구학적 특성-Kinematic Analysis-과 부시 (Bush)와 스프링 (Spring) 등의 컴플라이언스 (Compliance) 효과 - 쿼지스테틱 어낼러시스 (Quasistatic Analysis)-와 전체차량의 주행 시뮬 레이션 (simulation)을 통한 설계차량의주행안정성 검토-풀 비클 어낼러시스 (Full Vehicle Analysis)- 등이 있다. 이 글에서는 승용차의 현가장치중 대표적인형인 맥퍼슨 스터러트형에 대 하여 1) 기구학적 특성, 2) 부시와 스프링 등의 컴플라이언스 효과, 3) 전체차량의 주행 시뮬레 이션을 통한 차량의 주행 안정성 검토의 순으로 각 단계별 주요 검토 항목과 인자, 그리고 실제 차량에서의 현상에 대하여 소개한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.28-34
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• 2017

The vehicle stabilizer link is one of the suspension components that reduces the bumping and rolling during vehicle driving. However, this stabilizer link could be a source of the abnormal noises when its free gaps have higher than normal values. Therefore, the current study aims at investigating the quantitative relationships between the abnormal noises and free gaps of the vehicle stabilizer links, as well as the length of time that the vehicle stabilizer links could be used without generating abnormal noises. In this study, the abnormal noises were measured based on the magnitude of the stabilizer link vibration, while the free gaps were quantified through the force-displacement curves of the stabilizer links. Harsh durability tests were also conducted in order to quantify the operating cycles of the stabilizer links before generating the abnormal noises, along with the concomitant measurements of the free gaps. The current results showed that the abnormal noises of the stabilizer links were detected when its free gaps were larger than 0.12 mm. However, the free gaps of the stabilizer links, which are bigger than 0.1 mm, produced the abnormal noises at 1.5 million cycles under harsh durability test conditions. A parametric study in the future that would reflect the different shapes and sizes of the stabilizer links for diverse vehicles could determine more generalized relationships between the abnormal noises and free gaps of the vehicle stabilizer links.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1905-1913
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• 2011

The dynamic characteristic of bogie that is driving system of railway vehicle is very important regarding decision of vehicle characteristics as running safety and comport. The dynamic characteristic test of bogie is tested on full size in place on field testing on track. But, the testing on the full size caused many problems. To overcome these problem by full size test, the Railway Safety Research Center in Seoul National University of Science & Technology developed 1/5 scale size of small scale derailment simulator and is currently testing running stability of 1/5 scaled bogie. Also To take effectively advantage of running stability test using small scale derailment simulator in actuality design and reliability estimation, it is necessary comparison and examination with field test and theoretical analysis result In this paper. to achieve running stability analysis of 1/5 scaled bogie on small scale derailment. the program using MATLAB that is fast compose and analysis the motion equation of Saemaul power bogie is developed. It is achieved analysis according to various specification (weight, size, suspension, etc..) and is evaluated corelation between test result and dynamic characteristic of actual railway vehicle.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.16-21
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• 2017

Fire or electrical problem while DC electric traction vehicle operation caused by various reasons can lead to not only suspension of the operation, but also severe aftermath such as massive casualty. In this paper, fire analysis on DC electric traction vehicle caused by electrical breakdown on line breaker, which is in connection with the power supply, is presented. When the electric arc, the by-product of frequent line breaker operation, is not fully diminished, it leads to electrical breakdown and fire. Especially, electrical breakdown can be easily induced by the open-and-close operation of inner contractor inside line breaker, eventually followed by ground fault and generation of transient current. Electric arc is consequent on the ground fault and acts as possible ignition source, leading to fire. Also, during the repetitive operation of the line breaker, the contactor is separated each other and some copper powder is generated, and the copper powder provided breakdown path, resulting in fire.