• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.348-353
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• 2011

Iron fillings which were accumulated around the rail was often the cause of abnormal signal in case of signaling equipment using rail as transmission line. Iron fillings were generated on curved section of railroad due to the friction between rail and wheel, and metro line company urged to find the way to remove these iron fillings, because these were often the cause of abnormal signal. Magnetic device for trapping iron fillings around concrete slab tracks is introduced. The characteristics of magnetic device were analyzed using basic design and numerical analysis method. Magnetic device for trapping iron fillings were examined for application to the train which were operating in commercial line.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.1-10
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• 2011

This is a comparative study of three inertia navigation units and focuses on the verification of reliability about GPS/INS for the SmartUAV(DGNS). Those GPS/INS have been tested using a manned aircraft and an automobile. The comparative aspect of units include details about the GPS positions and the inertia sensor performance. With the flight scenario, the DGNS guarantees the reliability of the navigation operation and performs the flight test for the development of the SmartUAV.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.307-314
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• 2015

The purpose of this study is know the fuel economy of difference tractive resistance calculation methods on light duty low-floor bus. Two tractive resistance calculation methods(coastdown test and JFCM conversion formula) are tested to understand the difference of fuel economy. JFCM was developed for fuel economy regulations of heavy duty vehicle. That show a big difference as a result of the calculation using coastdown test and JFCM conversion formula. The difference of the tractive resistance affects the fuel economy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.18-25
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• 2020

With the development of water internet technology, data communication between objects is expanding. Research related to data communication technology between vehicles that incorporates related technologies into vehicles has been actively conducted. For data communication between mobile terminals, data stability, reliability, and real-time performance must be guaranteed. The 5 GHz Wi-Fi band, which is advantageous in bandwidth, communications speed, and wireless saturation of the wireless network, was selected as the data communications network between vehicles. This study analyzes how to design and implement a 5 GHz Wi-Fi network in a vehicle network. Considering the characteristics of the mobile communication terminal device, a continuous variable communications structure is proposed to enable high-speed data switching. We simplify the access point access procedure to reduce the latency between wireless terminals. By limiting the Transmission Control Protocol Internet Protocol (TCP/IP)-based Dynamic Host Configuration Protocol (DHCP) server function and implementing it in a broadcast transmission protocol method, communication delay between terminal devices is improved. Compared to the general commercial Wi-Fi communication method, the connection operation and response speed have been improved by five seconds or more. Utilizing this method can be applied to various types of event data communication between vehicles. It can also be extended to wireless data-based intelligent road networks and systems for autonomous driving.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.711-719
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• 2016

In this study, we derived an theoretical equation, using a simplified spring-mass model for the rolling stock, to obtain the overriding behavior of a leading vehicle, which is considered as the main factor in train accidents. To verify the derived equation, we created a simple 2D model based on the theoretical model, and a simple 3D model considering the characteristics of the power bogie. We then compared the theoretical results with the simulation results obtained using LS-DYNA. The maximum relative derivations in the vertical displacements at the first end-buffer, which is the most important point in overriding, were 3.5 [%] and 1.7 [%] between the two results. Further, we evaluated collision-induced overriding displacements using the theoretical equation for a rubber draft gear, a hydraulic buffer under various collision conditions. We have suggested a theoretical approach for the realization of overriding collision accidents or the energy absorption design of the front end of trains.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.32-38
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• 2020

This study examined the problems of existing vehicles to propose alternatives to improve the crashworthiness of railway freight cars through collision acceleration analysis using a one-dimensional collision analysis method. A collision scenario of railway shunting and crash accidents was selected from the collision accident cases and international standards. A one-dimensional collision simulation using LS-DYNA was performed according to those scenarios. As a result, the acceleration level of the freight wagon was calculated to be under 2g and was predicted to meet the EN 12663 standard in the shunting situation. On the other hand, the result of crash simulation with an impact velocity between 10 and 15 km/h revealed the shock absorber capacity of the railway coupler to be insufficient in a crash situation, resulting in increased acceleration, and carbody deformation could be predicted. As a method of improving the crashworthiness, a deformation tube-type energy absorber was applied to the coupler system, and collision analysis was performed again with new energy absorption strategy. Overall, the simulation showed that the acceleration level was decreased by 12% of the conventional freight-car energy absorption system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.61-69
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• 2020

This study examined the braking characteristics of a heavy haul freight train with P4a distribution valves applied to domestic high-speed freight trains. A freight train was composed of 50 cars, which is twice the normal operation. A braking test was performed to confirm the characteristics of the braking of a heavy haul. The brake cylinder pressures were measured for emergency and service braking on the 1st, 10th, 20th, 30th, and 50th cars. Because the brake signal is transmitted to the pressure through the braking tube connected to the end of the train, the rear vehicle is braking later than the vehicle ahead. Therefore, it is necessary to predict the brake pressures in all cars in a train to supplement the results of the limited tests and calculate the braking distance. The pressure in each car was determined using empirical models of linear interpolation, stepwise, and exponential models, which provided reliable information. The predictive results of the empirical models were compared with the measured results, and the exponential model was predicted relatively accurately. These results are expected to contribute to the safe operation of heavy haul freight trains and can be used to predict the braking distance and calculate the level of impact between vehicles during braking.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.951-960
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• 2006

Structural pavement analysis considering lateral loads of moving vehicle was carried out in order to simulate passing vehicle loads under various interface conditions. To verify of existing multi-layer elastic analysis of layer interface effect parameters, this study compared outputs by using ABAQUS, a three dimensional finite element program and KENLAYER, multi-layer elastic analysis as vertical load was applied to the surface of asphalt pavements. Pavement performance depending on interface conditions was quantitatively evaluated and fundamental study of layer interface effect parameters was performed in this study. As results of the study, if only vertical loads of moving vehicle is applied, subdivision of either fully bonded or fully unbonded is enough to indicate interface effect parameters. On the other hand, when lateral loads are applied with vertical loads, pavement behavior and performance are greatly changed with respect to layer interface conditions. The thinner thickness of the asphalt layer is and the smaller elastic moduli of the asphalt layer is, the more pavement behavior is influenced by interface conditions. In addition, regression analysis equation analytically computing tensile strain which was considered thicknesses and elastic moduli of the asphalt layer and layer interface effect parameters at the bottom of the asphalt layer was presented using database from numerical analyses on national pavement model sections.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.229-236
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• 2016

For this research, the trajectory of a projectile was simulated via the multibody dynamics analysis of a self-propelled mortar. The dynamic model was composed of a mortar model and a vehicle model, and was simulated using the RecurDyn program. Interior ballistic was applied to the mortar model, and exterior ballistic was conducted by Matlab using the simulation results of the interior trajectory. Through repetitive Monte-Carlo simulations, the accuracy of the mortar was analyzed by considering variations in the aiming angle and vehicle dynamic response.

• Journal of Korean Society of Transportation
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• v.28 no.4
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• pp.167-175
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• 2010

The ubiquitous transportation system environments make it possible to collect each vehicle's position and velocity data and to perform more sophisticated traffic flow management at the individual vehicle or platoon level through vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communication. It is necessary to develop a traffic flow management scheme to take advantage of the ubiquitous transportation system environments. This paper proposes an algorithm to advise the optimal speed for each vehicle according to the traffic flow condition. The algorithm aims to stabilize the traffic flow by advising the equilibrium speed to the vehicles speeding or crawling under freely flowing condition. And it aims to prevent or at least alleviate the shockwave propagation by advising the optimal speed that should dampen the speed drop under critical flow conditions. This paper builds a simulation testbed and performs some simulation experiments for the proposed algorithm. The proposed algorithm shows the expected results in terms of travel time reduction and congestion alleviation.