• Proceedings of the KSR Conference
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• 2007.05a
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• pp.109-114
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• 2007

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test to 120 km/h for estimating the running safety of express train in Incheon International Airport. As the test results, could confirm the curving performance and running safety of Incheon International Airport EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.378-383
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• 2004

Bogie is the connection device between carbody and wheel. It is the core part that exert a important effect on the passenger safety and running safety. Bogie largely consist of bogie frame, suspension, brake, wheel set. Static and Dynamic load have acted on it complexly. So when the bogie is designed, finite element method, static load test, fatigue test running test should be considered. Some bogie frame of high speed railway freight car have the problem. It's end beam was cracked. The crack of the end beam have a bad effect on brake system. ROTEM co. made an improved end beam and applied one set to freight car. this report showed the vibration characteristic which was compared conventional bogie to improved bogie for running safety.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.898-903
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• 2002

The railroad is a means of large transportation which has many talents such as a safety and a regularity. That is a results from various confidential performance tests and evaluations of the system. The railroad system consist of various subsystems - vehicle, power supply, signal, communications, track structures, operations, etc. Among them, as an item of safety evaluation there is a measurement of wheel/rail force, so called a measurement of derailment coefficient. This is a very important item because a derailment of a train will bring about a big accident. Especially it is more inportant in high speed rail of which operation speed is over two times as fast as existing rail. In this paper, it is introduced to preprocess the wheelset for measuring wheel/rail force of high speed rail, such as to treat a measuring wheelset, its finite element analysis, adhesion of strain gauges and static load test.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.56-61
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• 2006

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 110km/h for estimating the running safety of Incheon Int'l Airport EMU. As the test results, could confirm the curving performance and running safety of Incheon Int'l Airport EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• Smart Structures and Systems
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• v.21 no.5
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• pp.687-694
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• 2018

The problem of wheel tread defects has become a major challenge for the health management of high-speed rail as a wheel defect with small radius deviation may suffice to give rise to severe damage on both the train bogie components and the track structure when a train runs at high speeds. It is thus highly desirable to detect the defects soon after their occurrences and then conduct wheel turning for the defective wheelsets. Online wheel condition monitoring using wheel impact load detector (WILD) can be an effective solution, since it can assess the wheel condition and detect potential defects during train passage. This study aims to develop an FBG-based track-side wheel condition monitoring method for the detection of wheel tread defects. The track-side sensing system uses two FBG strain gauge arrays mounted on the rail foot, measuring the dynamic strains of the paired rails excited by passing wheelsets. Each FBG array has a length of about 3 m, slightly longer than the wheel circumference to ensure a full coverage for the detection of any potential defect on the tread. A defect detection algorithm is developed for using the online-monitored rail responses to identify the potential wheel tread defects. This algorithm consists of three steps: 1) strain data pre-processing by using a data smoothing technique to remove the trends; 2) diagnosis of novel responses by outlier analysis for the normalized data; and 3) local defect identification by a refined analysis on the novel responses extracted in Step 2. To verify the proposed method, a field test was conducted using a test train incorporating defective wheels. The train ran at different speeds on an instrumented track with the purpose of wheel condition monitoring. By using the proposed method to process the monitoring data, all the defects were identified and the results agreed well with those from the static inspection of the wheelsets in the depot. A comparison is also drawn for the detection accuracy under different running speeds of the test train, and the results show that the proposed method can achieve a satisfactory accuracy in wheel defect detection when the train runs at a speed higher than 30 kph. Some minor defects with a depth of 0.05 mm~0.06 mm are also successfully detected.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1439-1440
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• 2010

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.75-83
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• 2018

This paper described a results of dynamic stability by using wheel tracking test and unconfined compression test, in order to evaluate behavior characteristics on the developed pocketable expansion material for emergency restoration of ground cavity. The wheel tracking test result showed that the settlement increment ratio of the recovered ground by the expansion material was decreased compared to the sandy ground in high load condition. That is, it was confirmed that the expansion material was able to restrain the settlement due to the material stiffness, and the same results were obtained for the dynamic stability evaluation results. From the results of unconfined compression test, the pocketable expansion material was found to be able to fully support load on the restored cavity.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.137-143
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• 2016

The fifth wheel coupler is a heavy automotive coupling structure which connects a tractor and a trailer used for heavy-duty trucks widely. It is subjected to various loads simultaneously such as rolling, pitching and yawing loads as well as coupling frictional and impact loadings. Most of existing couplers have been overdesigned and, therefore, it is necessary to reduce the dead weight to increase the fuel efficiency. The topology optimization was applied in order to find conceptual layout designs which could show major load paths and ribs locations, and then the size structural optimization was performed in order to determine the heights and thicknesses of coupler ribs with the predetermined various loading conditions for the development of a new slim coupler with a minimum weight and high enough strength and stiffness. As the results of the topology optimum design, an efficient new coupling structure for truck trailers was designed. The weight of the new fifth wheel coupler was reduced by 4.9 %, compared with the existing one, even though all strength requirements were satisfied. The fatigue test of the new coupler was performed with cyclic vertical loads (+78.4 to +235.2 kN) and horizontal loads (-91.2 to +91.2 kN) simultaneously at 1 Hz and the life of 2,000,000 cycles were achieved without failure.

• Smart Structures and Systems
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• v.13 no.6
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• pp.993-1014
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• 2014

In civil engineering, revolving structures (RS) are a unique structural form applied in innovative architecture design. Such structures are able to revolve around themselves or along a certain track. However, few studies are dedicated to safety design or health monitoring of RS. In this paper, a wireless dynamic sensing system is developed for RS, and field tests toward a large revolving auditorium are conducted accordingly. At first, a wheel-rail problem is proposed: The internal force redistributes in RS, which is due to wheel-rail irregularity. Then the development of the sensing system for RS is presented. It includes system architecture, network organization, vibrating wire sensor (VWS) nodes and online remote control. To keep the sensor network identifiable during revolving, the addresses of sensor nodes are reassigned dynamically when RS position changes. At last, the system is mounted on a huge outdoor revolving auditorium. Considering the influence of the proposed problem, the RS of the auditorium has been designed conservatively. Two field tests are conducted via the sensing system. In the first test, 2000 people are invited to act as the live load. During the revolving process, data is collected from RS in three different load cases. The other test is the online monitoring for the auditorium during the official performances. In the end, the field-testing result verifies the existence of the wheel-rail problem. The result also indicates the dynamic sensing system is applicable and durable even while RS is rotating.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.6
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• pp.642-648
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• 2016

This paper deals with an analytical and experimental investigation to predict the axial thrust load that results from turbocharger operating conditions. The Axial forces acting on the turbocharger thrust bearing are caused by the unbalance between turbine wheel gas forces and compressor wheel air forces. It has a great influence on the friction losses, which reduces the efficiency and performance of high-speed turbocharger. This paper presents the calculation procedure for the axial thrust forces under operating conditions in a turbocharger. The first step is to determine the relationship between thrust forces and strains by experimental and numerical methods. The analysis results were verified by measuring the strains on a thrust bearing with the specially designed test device. And then, the operating strains and temperatures were measured to inversely calculate the thrust strains which were compensated the thermal effects. Therefore it's possible to calculate the magnitudes of the thrust forces under operating turbocharger by comparing the regenerated strains with the rig test results. It will possible to optimize the design of a thrust bearing for reducing the mechanical friction losses using the results.