• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.77-83
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• 2020

4WD technology is being actively applied to passenger cars. Therefore, dry multi-plate clutches are used for transfer cases. On the other hand, dry clutches have problems related to large vibrations and poor ride quality. To solve this problem, this paper proposes a multi-plate clutch with an MR fluid. When fastening the multi-plate clutch in the transfer case, the proposed MR clutch was applied to reduce the shock and friction, which is a key component in a four-wheel-drive system. MR multi-plate clutch has a fluid coupling mode and a compression mode. A torque model equation was derived for the optimal design. The analysis was performed using Ansys Maxwell to optimize the design parameters of the multi-plate clutch. Electromagnetic field analysis confirmed the strength of the magnetic field when the number of disks and plates were changed, and the maximum strength of the magnetic field was 0.45 Tesla. By applying this to the torque equation, the spacing between the plates was 2 mm, and the inner and outer diameters of the plates were selected to be 45 mm and 55 mm, respectively. Overall, this paper proposes an optimal design technique to maximize the performance of an MR multi-plate clutch.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.345-353
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• 2020

On conventional railway lines, trains with different speeds are operated. Therefore, trains moving on curved sections with cants must accept various ranges of balanced cants, cant deficiency, and cant excess, which is essential for the comfort and safety of train operation. In this study, the correlation between the curve radius, cant, and train speed on a track was analyzed to check the cant range that satisfies the criteria of train types, operation speed, cant deficiency, and cant excess. Also, the range of setting the cant by the curve radius and balanced cant were calculated by a regression analysis of train speed according to the frequency of operation in the case of mixed trains. The results could make it possible to improve the speed of the operation route, reduce the loss of ride quality, reduce the risk of derailing caused by cant deficiency, and minimize the load deflection by excess cant. This will ensure the safety of trains running on curves and improve the efficiency of track maintenance.

• Fire Science and Engineering
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• v.29 no.2
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• pp.44-53
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• 2015

This study is a survey research to improve the fire-fighting ambulance interior design safer and more efficient to identify the type of structure and functional problems 119 ambulance. When the paramedics and four degrees to over 755 people modify the target report and related literature on the future development of an ambulance for patient safety at the 2007 British National Patients Safety Agency (NPSA) and was used as a complementary tool. General characteristics questionnaire was composed of items for your design improvements for ambulance promote safety and efficiency. The data were collected by distributing a questionnaire e-mail or in person. The collected data were processed using the SPSS 20.0 statistical program, the general characteristics as frequency analysis, percentage, ambulance interior design improvement-related items were analyzed using the chi-square verified. As a result, this research elicited that vans converted fire ambulance cars have a problem with the narrow interior space and truck converted fire ambulance cars should be comfortable to drive in ride quality. In addition, we also found that the improvement of paramedics treatment position and the paramedic's personnel safety belt are required. Based on these results, we propose that a number of improvements are needed in the fire-fighting ambulance car.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.313-319
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• 2011

In a modern society, various type of transportation modes are utilized, among them the subway system is the one of the main transportation mode which more than 7.21 million people ride a day in Seoul. Due to the increased interests on the indoor air quality (IAQ) of underground facilities, public concerns on IAQ of subway system are increasing also. Platform screen door (PSD) recently installed at the whole stations of Seoul subway and tunnel washing-out appeared to be effective in reducing particulate matters in the platform and tunnel. However there has not been any attempt to improve IAQ of subway cabin inside. Most technologies for removing airborne particulate matters are known to be difficult to adopt on the subway cabin due to the problem of maintenance cost. Therefore, the object of this study is a practical development of cabin air cleaning system which can reduce the concentration of airborne particles and harmful gases at the same time. In this paper, we focused on the development of particle removing system utilizing a roll-filter for increasing operating time of air filter. The prototype of system was designed and manufactured based on the numerical prediction results. For rollfilter device, 5 candidate filter materials were tested in point of particle collection efficiency and pressure drop. It was found that the electrically charged filter material showed the highest performance among them.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.576-582
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• 2017

The switching system in a maglev train is an indispensable element for distributing train routes, and it should be designed to ensure safe operation. Unlike conventional wheels on rails, the switching track in EMS-type maglev is supported by a group of 3 to 4 steel girders. When the vehicle changes its route, the segmented track allows the girders to change from a straight position to a curved one with a small radius of curvature. Hence, the structural characteristics of the segmented switching system may affect the levitation stability of the maglev vehicle. This study experimentally evaluates the dynamic interaction between maglev vehicles and a segmented switching system. The results may be helpful for improving the switching system. The measured levitation and lateral air gaps were evaluated at a vehicle speed of 25 km/h, and the ride quality of the Maglev vehicle was determined to be "comfortable" according to the UIC 513 standard.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.1
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• pp.55-63
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• 2021

The roughness of the road is an important factor directly connected to the ride comfort, and is an evaluation item for functional evaluation and pavement quality management of the road. In this study, data on the road surface were acquired using the latest 3D geospatial information construction technology of ground LiDAR, drone photogrammetry, and drone LiDAR, and the accuracy and roughness of each method were analyzed. As a result of the accuracy evaluation, the average accuracy of terrestrial LiDAR were 0.039m, 0.042m, 0.039m RMSE in X, Y, Z direction, and drone photogrammetry and drone LiDAR represent 0.072~0.076m, 0.060~0.068m RMSE, respectively. In addition, for the roughness analysis, the longitudinal and lateral slopes of the target section were extracted from the 3D geospatial information constructed by each method, and the design values were compared. As a result of roughness analysis, the ground LiDAR showed the same slope as the design value, and the drone photogrammetry and drone LiDAR showed a slight difference from the design value. Research is needed to improve the accuracy of drone photogrammetry and drone LiDAR in measurement fields such as road roughness analysis. If the usability through improved accuracy can be presented in the future, the time required for acquisition can be greatly reduced by utilizing drone photogrammetry and drone LiDAR, so it will be possible to improve related work efficiency.