• International Journal of Highway Engineering
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• v.17 no.3
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• pp.125-132
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• 2015

PURPOSES : The present study aims to evaluate the added $CO_2$ emissions incurred from accelerating operation when to increase the speed up to the allowed level. METHODS : The methodology used are basically the relationship between emission rates and vehicle speeds or acceleration rate. These rates together are used to calculate the added $CO_2$ emissions incurred from accelerating operation. RESULTS : It was resulted that the all the emission rates are increasing proportionally to vehicle speeds or acceleration rates. Additionally, it was also resulted that allowable speeds increasing, the added emission rates are increasing rapidly. CONCLUSIONS : It may be concluded that if the allowable speed ranges are managed, $CO_2$ emissions during vehicle operation are much reduced. From this reason, it was found that the allowable speed during highway design and operation would be much necessary

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.145-151
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• 2018

In this study, the track-bridge interaction analysis was performed using an analytical model considering the track structure, thereby taking into account the linear conditions (R=650 m, cant variation $160{\pm}60mm$) and the dynamic characteristics of the bridge. As a result of the study, the allowable speed on the example bridge considered was calculated at 200 km/h based on vertical deflection, vertical acceleration, and irregularity in longitudinal level, but was also evaluated at 170km/h based on the coefficient of derailment, wheel load reduction, and lateral displacement of the rail head. It is considered desirable to set the speed 170km/h to the speed limit in order to secure the safety of both the bridge and the track. It is judged that there will be no problems with ensuring rail protection and train stability in the speed band.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.437-446
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• 2021

As flying vehicle's speed is getting faster, the magnitude of aerodynamic heating is getting bigger. High-speed vehicle's exterior skin is heated to hundreds of degrees, and electrical equipments inside the vehicle are heated, simultaneously. Since allowable temperature of electrical equipments is low, they are vulnerable to effect of aerodynamic heating. These days, lots of techniques are applied to estimate temperature of electrical equipments in flight condition, and to make them thermally safe from heating during flight. In this paper, new model building technique for thermal safety analysis is introduced. To understand internal thermal transient characteristic of electrical equipment, simple heating experiment was held. From the result of experiment, we used our new building technique to build thermal analysis model which reflects thermal transient characteristic of original equipment. This model can provide internal temperature differences of electrical equipment and temperature change of specific unit which is thermally most vulnerable part in the equipment. So, engineers are provided much more detailed thermal analysis data for thermal safety of electrical equipment through this technique.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1922-1928
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• 2011

The rail inclination produces a wider bearing area between the wheel and the rail by moving the wheel rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail inclination within the allowable range to ensure optimum track geometry. Neglecting the rail inclination geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail inclination in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail inclination and running speed.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1142-1147
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• 2011

The rail cant produces a wider bearing area between the wheel and the rail by moving the wheel-rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail cant within the allowable range to ensure optimum track geometry. Neglecting the rail cant geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail cant in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail cant and running speed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.411-416
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• 2014

In this research we present design optimization methods for a vehicle-mounted satellite antenna positioner. Our initial antenna positioner was conservatively designed to satisfy a worst case scenario where wind blew across the positioner at the speed of 120 km/h. Investigating stresses and safety based on Finite Element Methods (FEM), we find reflector support frames can be optimized to significantly reduce the weight of the positioner system. Thus, we optimize the reflector support frame from the given initial design while considering weight, maximum stress, maximum allowable deflection, cross section, and thickness. As a result, Shape C and the thickness of 2 mm are determined for the cross section of the reflector support frame. Applying this result, the weight of the new antenna positioner is 57.343 kg, which is decreased by 10.74% compared to the initial conservative design.

• Journal of Auto-vehicle Safety Association
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• v.8 no.3
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• pp.22-27
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• 2016

As a preliminary research to provide amendment for the engine performance test regulation of two-wheeled vehicles, the engine performance data are investigated in terms of maximum torque, rated power, and engine speed of motorcycles on sales in Korean market. Based on the engine performance database officially published to consumers, some forecasted problems are discussed when the maximum torque and the rated power are measured under the present test standards. EU and Korea regulations on engine performance test are carefully compared in terms of the accuracy of measurement devices, test procedures including data acquisition method, and allowable range of rated power measurement. Complementary items are discussed to eliminate ambiguities in the present regulation and to construct rational regulation system.

• Journal of the Korean Geotechnical Society
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• v.31 no.9
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• pp.29-38
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• 2015

In this study, track dynamic interaction characteristics caused by the vehicle running through transitional section such as bridge abutments were studied using the finite element analysis program. The geometric condition of track was generated by trigonometric function and allowable maximum track irregularity is determined by KORAIL track maintenance criteria. The sub-infrastructure under rail fastener system was modelled by 3D solid elements. To reduce computational cost only half track line is numerically considered and the roller boundary condition was applied to each side of model. In this study, the vehicle-track dynamic interaction analysis was carried out for standard Korean transition section of concrete track and the dynamic behaviors were investigated. The dynamic characteristics considered are wheel load variation, vertical acceleration at body, and maximum Mises stress at each part of transitional section.