• Proceedings of the KSR Conference
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• 2001.10a
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• pp.293-298
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• 2001

2span continuous Prestressed concrete girder railway bridges, span length 21m, 25m, 30m, 35m, that down-up method is applied and that designed to satisfy service load in accordance with design criteria of railway bridge can be dropped in their hight compared with existing simply supported prestressed concrete girder railway bridges. Continuous bridges result in guaranteeing safety against bending behavior by loading the practical railway moving load with each velocity. But the natural frequency of span length 21m is estimated not to satisfy recommended limitation of UIC 776-1R..

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.671-679
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• 2010

The construction of concrete track for the first time in Korea gives lots of meanings to civil engineering in various aspects. Settlement level needs to be kept minimal for the safety of the track. Concrete track has different structural characteristics comparing to conventional ballast track, so load distribution in concrete track is also different. Since it is the first time to build concrete track, there are very few experience and data available on the subject. Therefore it is important to evaluate how much load is transferred to the ground due to the running vehicle in concrete track and to determine the optimal thickness of layers. In this research, 9 individual earth pressure cells were installed at OOOk930 site in 2nd stage of Kyungbu high speed railway during under construction. The in-situ pressure data were measured at each layers during pump-car and locomotive were moving on the high speed railway surface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.595-598
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• 2000

This paper presents new cutting force measuring system for milling process. Usually, tool dynamometer is the most appropriate measuring tool in an analysis of cutting mechanism. High price and limited space, however, make it difficult to be in-situ system for controllable milling process. Although an alternative using AC current of servomotor has been suggested, it is unsuitable for cutting force control because of low bandwidth and noise. We suggest new cutting force measuring system, using two load cell placed between moving table and nut of ballscrew, and modelled on the system statically and dynamically. And to verify the accuracy of the proposed system, a series of carefully conducted experiments were carried out. Experiment results show that models are in reasonably good agreement with the experiment data.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.661-670
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• 2000

To investigate the characteristics of the dynamic response of long-span cable-stayed bridges due to various dynamic loadings likes moving traffic loads, two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. Futhermore case of asymmetric traffic loading clustered in one direction are also considered to study the torsional response of the bridge. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.502-505
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• 2003

The accidnet of breaking insulator rod leads to inturruption of moving the subway. We investigate the analysis of analysis of breaking accident of FRP insulator rod installed in dead section for catenary feeding system. To analysis of accident reason, SEM is used to analysis microscopic struture on surface of cross section of broken FRP insulator rod. At the same time, we examine the chage of atomic amount on solace of accident insulator through EDX analysis. Also, the test for tensional breaking load is condoled to check the mechanical strength.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.335-346
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• 2013

AASHTO LRFD and Korean Bridge Design Code (Limit State Design) specify to consider Truck and Lane load simultaneously determined from reliability-based live load model, and impact shall be applied to the truck load while it shall not be applied to the lane load. In this paper, vehicle-bridge interaction analysis under moving truck and lane loads were performed to estimate impact factor of the cables and girders for the selected multi-cable-stayed composite bridges with 230m, 400m and 540m main span. A 6-d.o.f. vehicle was used for truck load and a series of single-axle vehicles was applied to simulate equivalent lane load. The effect of damping ratio on the impact factor was estimated and then the essential parameters to impact factor, i.e., road surface roughness and vehicle speed were considered. The road surface roughness was randomly generated based on ISO 8608 and it was applied to the truck load only in the vehicle-bridge interaction analysis. The impact factors evaluated from dynamic interaction analysis were also compared with those by the influence line method that is currently used in design practice to estimate impact factor in cable-stayed bridge.

• International Journal of Highway Engineering
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• v.16 no.2
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• pp.61-71
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• 2014

PURPOSES : The first generation of wide base tires introduced in the early 1980s was found to cause a significant increase in pavement damage compared to dual-tire assemblies. However, wide base tires have evolved considerably, and a new generation of wide base tire is thought to be comparable to conventional dual tires for pavement damage. A challenge associated with using wide base tires is the accurate quantification of pavement damage induced by these tires. The objective of this study was to investigate the responses of flexible pavement to continuously moving vehicular loading under various tire configurations. METHODS : The comparison of the strain/stress responses of full-depth pavement caused by conventional dual tire assembly and new generation of wide-base tires was performed. The FE model incorporates linear viscoelasticity of asphalt material and continuous moving load using implicit dynamic analysis. RESULTS AND CONCLUSIONS : The result demonstrates that the new wide-base tires caused slightly more fatigue damage and less primary rutting damage in HMA layer than a dual-tire assembly, but caused more secondary rutting damage in subgrade than a dual tire assembly.

• KSTLE International Journal
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• v.2 no.1
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• pp.65-70
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• 2001

The wear debris is fall off the moving surfaces in oil-lubricated systems and its morphology is directly related to the damage and failure to the interacting surfaces. The morphology of the wear particles are therefore directly indicative of wear processes occurring in tribological system. The computer image processing and artificial neural network was applied to shape study and identify wear debris generated from the lubricated moving system. In order to describe the characteristics of various wear particles, four representative parameter (50％ volumetric diameter, aspect, roundness and reflectivity) from computer image analysis for groups of randomly sampled wear particles, are used as inputs to the network and learned the friction condition of five values (material 3, applied load 1, sliding distance 1). It is shown that identification results depend on the ranges of these shape parameters learned. The three kinds of the wear debris had a different pattern characteristics and recognized the friction condition and materials very well by neural network. We discuss how these approach can be applied to condition diagnosis of the oil-lubricated tribological system.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.365-372
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• 2010

Station is an important building in high-speed railway, and its vibration and noise may significantly affect the comfort of waiting passengers. A coupling vibration model for train-structure system is established to analyze and evaluate the vibration level of a typical waiting hall under dynamic train load. The motion of a four-axle vehicle with two suspension system is modeled in multi-body dynamics with linear springs and dampers employed. The station is modeled as a whole finite element structure which is 113 m in longitudinal and 163.5 m in lateral, and the stiffness of the station foundation is considered. According to the assumptions that both wheel and rail are rigid bodies and keep contact to each other in vertical direction, and the wheel/rail interaction and displacement coordination in horizontal direction is defined by the simplified Kalker creep theory, the vehicle spatial vibration model has 27 degrees-of-freedom. An overall analysis procedure is made of the train moving through the station, by which the dynamic responses of the train and the station are calculated. According to the comparison between analysis and test results, the actual connection status between different parts of the station is estimated and the vibration level of the waiting hall is evaluated.

• Journal of the Korean Society for Railway
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• v.14 no.1
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• pp.57-65
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• 2011

The estimation of traffic safety and passenger comfort when the train is running on the bridge is a estimation unique to the railway bridge. The standards for such estimation are included in the Eurocode, the Shinkansen design criteria, and the design guideline of the Honam High-speed railway. The items are bridge responses including vertical displacement of bridge, vertical acceleration, and slab twist. In principle, a direct estimation based on the train responses has to take place. However, the estimation based on the bridge responses can be seen as an indirect estimation procedure for the convenience of the bridge designer. First, it is general practice that traffic safety can be verified as a derailment coefficient or wheel load decrement The general method of estimating passenger comfort is to calculate the acceleration within the train car-body. Various international indexes have been presented for this method. In the present study, traffic safety and passenger comforts are estimated directly by bridge/train interaction analysis. The acceleration and wheel load decrement are obtained for the estimation of traffic safety and passenger comforts of a suspension bridge which has main span length of 300m. Also, the consideration of seismic load with simultaneous action of moving train is done for bridge/train/earthquake interaction analysis.