• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.4
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• pp.345-352
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• 2011

In the present study, a three-dimensional CFD simulation on aerodynamic lift acting on windshield wiper blades was performed to improve the wiping performance of a vehicle moving at a high speed. To predict the reliable flow characteristics around the windshield wiper system, the computational domain included the full vehicle model with detailed geometry of wiper blades in the wind tunnel. From the numerical results, the drag and lift coefficients of wiper blade were obtained for the performance of windshield wiper. With this aerodynamic characteristics of windshield wiper, the effects of wiping angles and hood tip angle on the wiping performance of the windshield wiper were evaluated.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.179-188
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• 2012

PURPOSES: The aim of this study is to analyze overloading control effectiveness of enforcing overweighted vehicles using HS-WIM (High-Speed Weigh-in-Motion) at main lane of expressway. METHODS: To analyze the weight distribution statistically, HS-WIM system should has an appropriate weighing accuracy. Thus, the weighing accuracy of the two HS-WIM systems was estimated by applying European specifications and ASTM (American Standards for Testing and Materials) for WIM in this study. Based on the results of accuracy test, overweight enforcement system has been operated at main lanes of two expressway routes in order to provide weight informations of overweighted vehicle in real time for enforcement squad. To evaluate the overloading control effectiveness with enforcement, traffic volume and axle loads of trucks for two months at the right after beginning of the enforcement were compared with data set for same periods before the enforcement. RESULTS: As the results of weighing accuracy test, both WIM systems were accepted to the most precise type that can be useful to applicate not only statistical purpose but enforcing on overweight vehicles directly. After the enforcement, the rate of overweighted trucks that weighed over enforcement limits had been decreased by 27% compared with the rate before the enforcement. Especially, the rate of overweighted trucks that weighed over 48 tons had been decreased by 91%. On the other hand, in counterpoint to decrease of the overweighted vehicle, the rate of trucks that weighed under enforcement limits had been increased by 7%. CONCLUSIONS: From the results, it is quite clear that overloading has been controlled since the beginning of the enforcement.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2173-2178
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• 2008

Railroad is the major factor of vibration source in railway vehicles, and it must carefully maintained the original condition to secure the safety and good ride comfort of passenger. Measuring the condition of rail irregularities such as surface, alignment, gauge, twist and cant etc is required to maintain the good performance of railroad. Currently, the various rail irregularity measurement systems(EM120, ROGER1000K and the Total Rail Irregularity Measurement system of Korea High Speed Train) are operated in Korea to estimate the rail irregularity. It is hard to verify the correlation of one rail irregularity data of a measurement system with the other, because they have been adopted different rail irregularity estimation methods. The best method securing the reliability of the irregularity data is the direct confirmation on the ground where the measurement system had detected as a fault section, but it is impossible to apply all sections simultaneously due to limitation of time, labor, cost and equipments. There is a method to secure the reliability of the data by using acceleration values. Rail irregularities, the major factor of vibration in railway vehicle, are transmitted to the vehicle acceleration through masses, springs, dampers and joints as the system dynamic formation. In this study, Transition Function has been adopted by using the rail irregularity and the acceleration value regarding as input & output parameters respectively. It has been verified by comparing the analyzed results with real measured irregularity data from the Total Rail Irregularity Measurement system of Korea High Speed Train. Also various methods has been accomplished to verify the correlation between rail irregularities and acceleration values.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.942-944
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• 2017

High-speed vehicles are subjected to complex loads, such as acoustic pressure from the engine at launch and aerodynamic heating and aerodynamic pressure during flight. A thermal protection system panel is required to protect internal systems such as the fuel tank of the vehicle from the external environment. This study defines analytical models for heat transfer and thermal structure characteristics of the thermal protection system panel. Furthermore, the study performed parameters analysis to achieve the thermal structural integrity and to make it lighter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.95-104
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• 2008

Dynamic behaviors of the two-span continuous bridge which is one of prototypes on Gyoung-Bu high-speed railway are analyzed and some methods for reducing the resonance of the bridge are proposed. The bridge is modeled as a two-span continuous beam and the load is a vehicle of TGV-K (2p+18T) with length of 380.15 meter traveling on the railway bridge at some constant velocity. The equations governing the dynamic behaviors of the bridge are partial differential equations produced by using a system with distributed mass and elasticity. The analysis of the governing equations is performed by the mode superposition method which has modal coordinates solved by Duhamel's integral. Without considering the train velocity the dynamic reponses can be greatly reduced at some special lengths of bridge. It is different from the results of simple bridges researched so far. When the dynamic responses increase rapidly to make a resonance phenomenon depending on the train velocities, the several methods are proposed to deduce the resonance.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.51-58
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• 2002

A simulation model has been developed to predict the performance of 5-valve gasoline engine by gas exchange process with combustion model. In this study, we simulated the intake flow characteristics and performance of 5-valve engine with entwine speed and we compared the 5-valve engine performance with that of 4-valve engine. As a result. the calculated value was in consistency with the measured value relatively. The performance of 5-valve engine was higher than that of 4-valve engine in high engine speed region.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.235-237
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• 2006

Tilting trains are now an established feature of railway operations throughout the world For intercity traffic, tilt provides operators with Increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the Power suppling device is very essential for stable electric power supply.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.623_624
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• 2009

This paper deals with the characteristic analysis of electro-magnet (EM)-permanent magnet (PM) hybrid levitation and propulsion device for magnetically levitated (maglev) vehicles. Several machine characteristics such as levitation force with/without control current and thrust are described. In order to verify the analysis results and feasibility of high-speed operation of the maglev vehicle, real-scale static test set is implemented and tested.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.524-531
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• 2010

The automobile networks consist of the communication bus systems which become independent and heterogeneous each other. Most often, the CAN buses are implemented in a car in order to connect all the electronic control units in various ways. Thus, some gateways are necessary for exchanging the useful information between electronic control units on the buses. The automobile body networks group is divided into two kinds on a large scale, namely the low-speed bus and the high-speed bus. To interchange messages between the two, a CAN signal gateway is designed and implemented in a miniature scale. A network analyzer (called "Vehicle spy") and an oscilloscope monitor network situation to confirm the due operation of CAN signal gateway. The efficiency of the designed gateway is evaluated. The more message thread increased, the more efficiency decreased.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.30-37
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• 2017

When a wheel profile of a train-tram is designed, both train and tram tracks should be considered. This study designed a wheel profile that enables high-speed driving(200km/h) on the train track and low speed driving on the tram track with multiple sharp curves. The study used the approximation optimization method to reduce cost and time, used the sequential quadratic programming method as the optimized algorithm, and the central composite design and response surface method as an approximate model. The optimized wheel shape based on this approximation optimization method reduced wear of the initial wheel showed a better performance in terms of derailment and lateral force.