Kyeong Uk Kim

Analysis of transmission load of agricultural tractors

The objectives of this study were to analyze the load acting on the input shaft of the transmission of an agricultural tractor when it conducts plowing, rotovating and transporting operations under the Korean farming conditions. A survey was conducted to investigate the operational characteristics of such tractor works. To measure the load, a torque transducer was developed and installed on the input shaft of the transmission. A radio telemetry system was used to transmit the strain signals from the torque transducer to a data acquisition system. The time histories of the measured torque signals were digitized and analyzed using the rain-flow cycle counting method to determine their cyclic distributions. The load spectra thus obtained from the different operations were compared and their severeness to the transmission was discussed.

Effect of inflation pressure on tractive performance of bias-ply tires

Abstract This study was to investigate the effect of inflation pressure on the tractive performance of bias-ply tires for agricultural tractors. Traction tests were conducted at velocities of 3, 4, and 5.5 km h −1 under four different surface conditions using a 13.6–28 6PR bias-ply tire as driving the wheel of the test tractor. When the inflation pressure was reduced from 250 to 40 kPa by a decrement of either 30 or 50 kPa depending upon the test surfaces, some of the test results showed that the traction coefficient and tractive efficiency were increased maximally by 14 and 6%, respectively, at 20% slip. However, such improvements in traction were not statistically consistent enough to find any rules regarding the effect of inflation pressure of bias ply tires on the tractive performance of tractors.

Modeling motion resistance of rigid wheels

Abstract A mathematical model was developed to describe the motion resistance of rigid wheels under self-propelled conditions where no drawbar pull is developed. The modeling was based on the concept that the work required to overcome the motion resistance is equal to the energy dissipated in compacting the soil beneath the wheel. Slippage of the wheel was also considered in the modeling. Finally the validity of the proposed model was discussed.

Energy Efficiency Classification of Agricultural Tractors in Korea

Purpose: This study was conducted to classify the energy efficiency of 131 tractor models tested during from 2006 to 2010 in Korea. Methods: Four sub-indexes were developed using the fuel consumptions at 60% and 90% of rated speed with partial loads and at pull speeds of 3.0 km/h and 7.5 km/h with maximum drawbar pull. Weighting factors of the sub-indexes were also considered to reflect the characteristics of tractor`s actual working hours in Korea. Four sub-indexes were integrated into a classification index. Using the developed classification index, a five-classification system was made on the basis of normal distribution of tractors over the classification range. Percentage of 1st grade interval was expected to be close to 15%, 2nd grade 20%, 3rd grade 30%, 4th grade 20%, 5th grade 15%. Results: Number of 1st grade was 21, 2nd grade 23, 3rd grade 39, 4th grade 33, 5th grade 15 among 131 models. Conclusions: Classification index was developed by integrating four sub-indexes. By the classification method using developed index, distribution of classified tractors was acceptable for practical application.

Effects of Distribution of Axle Load and Inflation Pressure of Tires on Fuel Efficiency of Tractor Operations

, 2011)This study was conducted to investigate the effects of axle weight distribution and inflation pressure of tire on the fuel economy of tractors as well as operational range of tractor engine in terms of engine speed and power when a 4WD tractor of 38.2 kW rated power at 2500 rpm is used for plowing and flooded-field rotavating in paddy fields. (1) Plowing operation required an average engine power of 9.6~13.5 kW which equals 25~35% of rated PTO power. Engine speed ranged from 1,320.4 to 1,737.4 rpm, work velocity from 3.4 to 4.8 km/h, and fuel consumption from 3.2 to 4.2 L/h, respectively.(2) Flooded-field rotavating required an average engine power of 11.5~18.5 kW which equals 30~48.4% of rated PTO power. Out of this 6.2~12.2 kW was used for PTO power. Engine speed ranged from 1,557 to 2,067 rpm, work velocity from 2.5~5.4 km/h and fuel consumption from 3.2~5.5 L/h, respectively.(3) Axle weight distribution, inflation pressure of tire and moisture content of soil did not affect significantly the specific volumetric fuel consumption but affected significantly the fuel consumption per unit area of operation. Fuel savings amounted to 65% in plowing operation and 20% in flooded-field rotavating when the axle weight distribution and inflation pressure of tire were optimally adjusted.(4) Optimal adjustment of axle weight distribution and inflation pressure of tire are expected to save fuel consumption by 10~65% per unit area of operation in plowing and 10~20% in flooded-field rotavating.

Farm Mechanization Policies in Korea

Abstract Korea has achieved successful farm mechanization over the past 45 years. Mechanization for rice production is almost complete and that for horticulture and livestock is well under way. In this regard, the Korean government has instituted a number of policies to promote farm mechanization, including distribution, production, marketing, inspection, after-sales service, and the training of end users of agricultural machines. This paper reviews the progress of Koreas farm mechanization and the policy directions of the Korean government with respect to the promotion of farm mechanization. Some problems in the implementation of the policies are discussed. The successful actualization of the Korean farm mechanization represents a good benchmark for policy makers in developing countries, particularly for those who preside over rice growing regions in Asia. A countrys farm mechanization policies affect the farmers, machine manufacturers, and agricultural productions of the country; thus, such policies should be implemented on the basis of the countrys local conditions and rural economy. To achieve successful farm mechanization, the rural economy must remain economically viable, and there must be a reduction in rural labor force. Koreas success has been due to its industrial development.

Performance Improvement of the Horizontal Control System for a Tractor Implement Using Sensor Signal from the Front Axle

, 2016Purpose: Many tractors have adopted the horizontal control system designed to maintain the three-point mounted implements in horizontal position when they are tilted sideways. The control system rotates the implement in the opposite direction to the inclination of rear axle of the tractor. However, the current control system was found to have poor performance in accuracy and response. A new control system was therefore developed to improve the performance. Methods: The new control system was designed to get the response of the implement to be started earlier by using the tilt information from the front axle of the tractor. By this approach, the rotation of the implement can be adjusted as required to make it horizontal at the expected time, even though the response is slow. The optimal values of the control parameters for the new system were determined by computer simulation and validated by a performance test conducted with an obstacle of 120 mm height on a flat concrete surface. The performance of the control system was evaluated by the root mean square error (RMSE) of the rotation angle of the implement with respect to the actual inclination of the rear axle. Results: The new control system reduced the RMSE of the current control system by 44.6% indicating a high performance improvement. The inclination of the front axle was easily obtained from a sensor mounted on the front axle of the tractor and used as input to the new control system. Conclusions: The method of getting the response of the implement to be started earlier by utilizing the inclination information of the front axle can be applied to improve the performance of the current control system at least cost.Keywords: Horizontal control system, Implement, RMSE, Tractor

Classification Index and Grade Levels for Energy Efficiency Classification of Agricultural Heaters in Korea

Purpose: This study was carried out to develop a classification index and grade levels to rate agricultural heaters for energy efficiency classification. Methods: The classification index was developed mainly by taking simplicity of calculation and easy access to relevant data into consideration. The grade levels were developed on the basis of a 5-grade classification system in which graded heaters are to be normally distributed over the grades. The value of each grade level were determined in terms of the classification index values calculated using the published performance data of agricultural heaters tested at the FACT in Korea over the past 12 years. Results: The thermal efficiency of agricultural heaters based on the enthalpy method was proposed as a reasonable classification index. The grade levels were proposed in equation form for three types of agricultural heaters: fossil fuel heaters, wood pellet heaters and wood pellet boilers. A reasonable energy efficiency classification of agricultural heaters could be performed using the proposed classification index and grade levels. Conclusions: It is expected that energy saving programs will be extended to agricultural machines in the near future. The classification index and grade levels to rate agricultural heaters for energy efficiency classification were developed and proposed for such near future to come.