• Proceedings of the KSME Conference
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• 2003.04a
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• pp.780-785
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• 2003

Maintaining track tension in tracked vehicles minimizes the excessive load on the tracks and prevents the peal-off of tracks from the road-wheel, and adequately guarantees the stable and improved driving of the tracked vehicles. However, the track tension cannot be easily measured due to the limitation in the sensor technology, harsh environment, etc. In this study, the track tension is estimated in real-time from the measurable signals of tracked vehicles and controlled based on a fuzzy logic controller. The proposed control system is implemented on tracked vehicles and its performance is evaluated under various driving conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.694-697
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• 1997

As the life cycle of the vehicle become shorter, the method that reduce the development time of new model become more important. In this reason, the development of the simulator that provides similar environment with the actual vehicle load characteristics is increasing. In this paper, the link unit of the 3-axis road simulator is designed and simulated with dynamic analysis software ADMS. and the maximum stress and strain are analyzed for the safety of link and specifications of optimal design using finite element method.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.137-144
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• 2005

The possibility of resonance exists always in railway bridges unlike highway bridges because railway bridges are loaded repeatedly by specific trains which has equidistant wheel loads. Resonance phenomenon of the bridge can be broken out when exciting frequencies by tram determined from the speed and effective beating internal coincides with natural frequencies of the bridge Excessive fluctuations of dynamic displacements and accelerations by resonance cause unpleasant passenger comfort and instability of railway structures. On the other hand, resonance suppression phenomenon that all the previous loads which pass through the bridge sum to zero can be occurred. In case we apply this resonance suppression properly, design of stable railway bridge from dynamics point of view can be made. In the present study, most dominant beating internal of conventional trams will be find. A(ter that. specific span length of the bridge which derives resonance suppression can be selected for railway bridges which accomplishes superior dynamic behavior.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.472-475
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• 2003

Electric Power Steering (EPS) mechanism has become widely equipped in passenger vehicle due to the environmental consciousness and higher fuel efficiency. This paper describes the development of co-simulation technique and simulation integration technique of EPS control system with dynamic vehicle model. A full vehicle model interacted with EPS control algorithm is concurrently simulated on a single bump road condition. Dynamic responses of vehicle chassis and steering system resulting from road surface impact are evaluated and compared with proving ground experimental data. The comparisons will show reasonable agreement on tie-rod load. rack displacement, handle-wheel torque and tire center acceleration. This developed simulation capability can be used for EPS performance evaluation and calibration as well as for vehicle handling performance integration and synthesis.

• Journal of the Korean Society for Railway
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• v.14 no.1
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• pp.39-48
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• 2011

The paper describes four practical cases of railway structure concerning a three-dimensional numerical approach to analyse dynamic soil-structure interaction(SSI)of railway tracks on layered soil under transient load in the time domain. The SSI-Model has been implemented in TDAPIII accounting for nonlinear properties of the track and soil. The approach can be also be used to calculate vibration propagation in the soil and its effect on nearby buildings and structure. The Method is applied to analyse the dynamic response of railway tracks due to a moving wheel set. Finally some sample are given in order to reduce the vibration at the point of emission, at the transmission path and the structure itself.

• Wind and Structures
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• v.19 no.1
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• pp.1-14
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• 2014

Rail-mounted cranes can be easily damaged by a sudden gust of wind while working at a running speed, due to the large mass and high barycenter positions. In current designs, working rail-mounted cranes mainly depend on wheel braking torques to resist large wind load. Regular brakes, however, cannot satisfactorily stop the crane, which induces safety issues of cranes and hence leads to frequent crane accidents, especially in sudden gusts of wind. Therefore, it is necessary and important to study the braking performance of working rail mounted cranes under wind load. In this study, a simplified mechanical model was built to simulate the working rail mounted gantry crane, and dynamic analysis of the model was carried out to deduce braking performance equations that reflect the qualitative relations among braking time, braking distance, wind load, and braking torque. It was shown that, under constant braking torque, there existed inflection points on the curves of braking time and distance versus windforce. Both the braking time and the distance increased sharply when wind load exceeded the inflection point value, referred to as the threshold windforce. The braking performance of a 300 ton shipbuilding gantry crane was modeled and analyzed using multibody dynamics software ADAMS. The simulation results were fitted by quadratic curves to show the changes of braking time and distance versus windforce under various mount of braking torques. The threshold windforce could be obtained theoretically by taking derivative of fitted curves. Based on the fitted functional relationship between threshold windforce and braking torque, theoretical basis are provided to ensure a safe and rational design for crane wind-resistant braking systems.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.39-45
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• 2008

The most important elements in flexible pavement design criteria are stress and strain distributions. To obtain reasonable stress and strain distributions in pavements, moving wheel loads must be applied to analyze the pavement responses. In this study, finite element analysis was used to identify the three-dimensional states using the vehicle load into a constant-position / time-variable load (25, 50 and 80km/hr). In an elastic system, the strain is the same in both longitudinal and transverse directions under a single wheel. However, the same is not necessary in a viscoelastic system. Test results showed that the maximum values between transverse and longitudinal strains the bottom of asphalt concrete base layers under 25km/hr were were about 40 percent.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.15-20
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• 2017

This study analyzed the load change of the gear generated by the operation of the vehicle recliner through Finite Element Analysis. The basic model of the recliner used was a commercial product, and the effect of the seat frame was excluded. The load conditions applied to the recliner were set considering gravity, the mass of the seat's back frame, and the weight of a person. The operating mode was set to move the seat back from the vertical to the reclined position. As a result, it was found that the tooth bending amount of the gear rim and wheel increased from the cam rotation angle of 450 degrees, and a change in the contact ratio occurred. Furthermore, excessive torque fluctuations occurred in the ranges of 390 to 450 and 750 to 710 degrees. It was found that this occurred in the region of about 30 degrees before and after the point where the x-axis direction load is larger than the y-direction load. From this torque fluctuation it was determined to likely to cause chattering noise.

• International Journal of Highway Engineering
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• v.18 no.4
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• pp.29-35
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• 2016

PURPOSES : The new waste management policy of South Korea encourages the recycling of waste materials. One material being recycled currently is tire-derived fuel (TDF) ash. TDF is composed of shredded scrap tires and is used as fuel in power plants and industrials plants, resulting in TDF ash, which has a chemical composition similar to that of the fly ash produced from coal. The purpose of this study was to evaluate the properties of an asphalt concrete mix that used TDF ash as the mineral filler. METHODS : The properties of the asphalt concrete were evaluated for different mineral filler types and contents using various measurement techniques. The fundamental physical properties of the asphalt concrete specimens such as their gradation and antistripping characteristics were measured in accordance with the KS F 3501 standard. The Marshall stability test was performed to measure the maximum load that could be supported by the specimens. The wheel tracking test was used to evaluate the rutting resistance. To investigate the moisture susceptibility of the specimens, dynamic immersion and tensile strength ratio (TSR) measurements were performed. RESULTS : The test results showed that the asphalt concrete containing TDF ash satisfied all the criteria listed in the Guide for Production and Construction of Asphalt Mixtures (Ministry of Land, Infrastructure and Transport, South Korea). In addition, TDF ash exhibited better performance than that of portland cement. The Marshall stability of the asphalt concrete with TDF ash was higher than 7500 N. Further, its dynamic stability was also higher than that listed in the guide. The results of the dynamic water immersion and the TSR showed that TDF ash shows better moisture resistance than does portland cement. CONCLUSIONS : TDF ash can be effectively recycled by being used as a mineral filler in asphalt, as it exhibits desirable physical properties. The optimal TDF ash content in asphalt concrete based on this study was determined to be 5%. In future works, the research team will compare the characteristics of asphalt concrete as function of the mineral filler types.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.309-317
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• 2007

In this study, we conducted a vibration fatigue analysis of the lower control arm in a vehicle suspension system. The vehicle was driven during the tests so that the dynamic effects could be taken into account. The dynamic load of the frequency domain was superimposed on the frequency response analysis. We performed a virtual proving ground test using multi-body dynamics, along with a finite element analysis and fatigue life predictions. Shape optimization was also considered using the design of the experimental approach, and a response surface analysis was performed to improve the durability performance of the lower control arm. We identified the elements that had the most influence on the optimal shape of the finite element model and analyzed the sensitivity of those elements. Then the optimal points that minimized the amount of damage to the areas of interest were determined through a response surface analysis. The results suggested that the fatigue life of the model increased as its mass was not increased excessively, and demonstrated that these design procedures yielded an appropriate optimized lower control arm model.