• Proceedings of the KSR Conference
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• 2011.05a
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• pp.93-97
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• 2011

This paper presents the performance and test results of propulsion system which is met the requirements of urban MAGLEV. The design of propulsion system should be considered the effect of attractive force by the magnetic levitation and train running resistance. In this paper, the tractive and braking thrust are calculated and the train performance is simulated for the service track. Finally the test results of complete car are shown to verify the performance.

• Journal of Biosystems Engineering
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• v.14 no.3
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• pp.151-157
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• 1989

A mathematical model was developed to predict traction forces of rigid wheels. The modeling was based on the energy principle that the total energy delivered to a driving wheel is equal to the works done by the useful traction force and motion resistance of that wheel. The effect of the wheel slippage was also included in the modeling. Verification of the proposed model was provided by comparing the tractive coefficients predicted by the model to those obtained experimentally at the in-door soil bin tests. The model predictions were found to be a reasonable agreement with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.917-918
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• 2010

• The Journal of Korea Robotics Society
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• v.8 no.2
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• pp.116-128
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• 2013

This paper focuses on development of a testbed for analysis of robot-terrain interaction on rough terrain and also, through one wheel driving experiments using this testbed, prediction of maximum velocity and acceleration of UGV. Firstly, from the review regarding previous researches for terrain modeling, the main variables for measurement are determined. A testbed is developed to measure main variables related to robot-terrain interaction. Experiments are performed on three kinds of rough terrains (grass, gravel, and sand) and traction-slip curves are obtained using the data of the drawbar pull and slip ratio. Traction-slip curves are used to predict driving performance of UGV on rough terrain. Maximum velocity and acceleration of UGVs are predicted by the simple kinematics and dynamics model of two kinds of 4-wheel mobile robots. And also, driving efficiency of UGVs is predicted to reduce energy consumption while traversing rough terrains.

• Ecology and Resilient Infrastructure
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• v.4 no.1
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• pp.24-33
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• 2017

This study investigates the flow characteristics and bed changes with discharge using a two-dimensional numerical model, Nays2DH. The water depth at the outer part of curved channel is formed deeper from the narrow part after passing through the curved part. The point bar is developed in the wide section and water depth is shallow in the inside of the curved section. The flow is concentrated in the outer pater of the meandering section, which leads to the deep water. In the downstream section where the straight line formed, the flow is concentrated at the center of the bed. Alternating deep water and shallow places are generated due to the continuous formation of meandering. These characteristics are formed by the influence of strong two-stream flow in meandering stream. The dimensionless tractive force is also large in the region where the flow velocity is concentrated. However, in the narrow and sharp meandering river reaches, the pattern of bed changes and the spatial distribution patterns of flow velocity and dimensionless tractive force are inconsistent in the narrow and sharp meandered reaches due to the strong secondary flow.

• Journal of Biosystems Engineering
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• v.43 no.2
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• pp.83-93
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• 2018

Purpose: This study derived the consumed power and load characteristics of a tillage operation performed in an upland field located in Seomyeon, Chuncheon, Rep. Korea, where potatoes and cabbages were cultivated in two crops. Methods: A plow and rotavator were mounted on a tractor with 23.7 kW of rated power to perform the tillage operation. The work conditions were determined, considering the actual working speed of the tillage operation performed by the local farmers. The power consumption of the rear axle, engine, and power take-off (PTO), PTO torque, and tractive force were measured under each work condition. The consumed power and load characteristics were analyzed using their average values. Results: The rotary-tillage operation consumed more engine power than the plow operation for the same tractor-transmission gear condition. The PTO in the rotary-tillage operation and the rear axle in the plow operation consumed the most power. The power consumption of the engine and the PTO for the rotary-tillage operation tended to increase as the transmission gears of the tractor and the PTO became higher. In contrast, the rear-axle power consumption was insignificant. In addition, the PTO torque tended to rise as the tilling pitch increased. For the plow operation, the drawbar power and the rear axle power accounted for 68-90% of the engine power. The engine and rear axle power, drawbar power, and tractive force tended to rise as the working speed increased. Conclusions: The power consumption and load characteristics differed for the plow and rotary-tillage operations. They may also differ depending on the soil conditions. Therefore, the power consumption and load characteristics in various work environments and regions should be analyzed, and reflected in the design of tractors and working implements. The results derived from this study can be used as a reference for such designs.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.751-754
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• 2008

Recently according to increasing of damage in creeks, it has been needed to develop a close-to-nature creek improvement technique considering flood safety as well as the functions of ecosystem and scenery preservation. In this study, the monitoring on creeks in seven provinces was accomplished to develop the technique applicable to domestic creeks between 2002 and 2007. Although the riparian ecosystem was disturbed, after just finishing the improvement on pilot creeks, the result of monitoring showed that restoration rates of creeks were satisfactory by constructing close-to-nature creek revetments. However it is hard to analyze on restoration and permissible tractive force of each revetments constructed in most creeks, because of insufficient monitoring data. Therefore the feasible study on the close-to-nature creek revetments should be performed in the near future through continuous monitoring on creeks.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.404-412
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• 1996

For the cultivation of big agricultral areas high performance machinery is needed. The need to increase working productivity also leads to powerful machinery. The total weight of new tractor generations increases and with it their axle and wheel weight reaches a soil damaging extend. Besides carrying the mass of the tractors and harvesting-machines the chassis must transmit driving force onto the ground(Tab. 1). To decrease soil damaging compaction a number of technical solutions have been developed. Broad tyres are being used to minimize the contact-area pressure by using low tyre air pressure. For enlarging the contact area there are two-possibilities : to build a brought or a long contact area. done for instance in caterpillar tracks.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.4
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• pp.366-374
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• 2003

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force using load torque disturbance observer. Based on this estimated adhesive effort, the re-adhesion control Is peformed to obtain the maximum transfer of the tractive effort.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.45-53
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• 1998

Traction control systems(TCS) improve vehicle acceleration performance and stability, particularly on slippery roads through engine torque and/or brake torque control. This research mainly deals with the engine control algorithm based on adjustment of the engine throttle valve opening. Hardware-in-the-loop simulation(HWILS) is carried out where the actual hardware is used for the engine/automatic transmission and TCS controller, while various vehicle dynamics are simulated on real-time basis. Also, use of the dynamometer is made in order to implement the tractive force that a road applies to the tire. Although some restrictions are imposed mainly due to the capability of the synamometer, simplified HWILS results show that the slip control algorithm can improve the vehicle acceleration performance for low-friction roads.