• Journal of Biosystems Engineering
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• v.34 no.1
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• pp.1-7
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• 2009

In order to evaluate environmental comfort of tractor cabs, temperature, relative humidity and noise within the cab were taken from 31 tractors during plowing and rotovating operations. The temperature and humidity were evaluated with regard to the comfort zone of KS B ISO 14269-2 and PMV of ISO 7730. The noise was evaluated with regard to the permissible sound level of OSHA for daily exposure of 8 hours. The collected data indicated that thermal environment of the cabs was out of the comfort zone, which meant tractor operators worked under uncomfortable thermal conditions. Difference in the thermal comfort by tractor power and maker, and type of works was not found. However, 25% of the studied tractors showed PMV in a range of -0.5 to +0.5, which indicated their operators worked under the comfort criteria. PMV was improved when the cab was air-conditioned. Levels of measured cab noise were lower than the permissible criteria, and 76.7% of the studied tractors had cab noise ranged from 75 to 85 dBA. There was a tendency that high powered tractors, rotovating operations and locally-made tractors had greater cab noise levels. However, their differences were insignificant.

• Journal of Biosystems Engineering
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• v.20 no.2
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• pp.117-126
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• 1995

High level of tractor noise may reduce operator's work performance and cause a hearing problem. This study was carried out to investigate the cab noise of a selected agricultural tractor. The noise was measured and analyzed in terms of sound and sound intensity levels. Form the results it was known that a structure-born noise was induced from the feet-rest and rear floor panel of the cab. The air-borne noise caused mainly by the engine was transmitted into the operator's position through the small openings of cab structures in the operator's lower front area.

• Journal of Biosystems Engineering
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• v.20 no.2
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• pp.127-132
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• 1995

In the first part of this paper, an analysis of the cab noise of a selected agricultural tractor was presented. In this study, using the results of the previous analysis, two passive noise control measures of the sound insulation and absorption were conducted to reduce the noise level inside the cab. These measures of noise control reduced the total noise level by 6.2㏈(A) at the operator position inside the cab. In order to further reduce the cab noise, particularly, of lower frequencies than 630Hz, stiffness and damping of the floor panel should be enforced. It was also suggested that a proper suspension for the cab mounting is necessary to reduce the level of structure-born noises.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.237-244
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• 2001

This work was intended to investigate the effect of vibration transmission paths on the ride vibration of tractor during the rotavating and transporting operations by applying the vibration path analysis method. Accelerations at the cab mounts were measured during the rotavating and transporting operations. Ride vibrations at the sear were than calculated using the measured accelerations at the cab mounts, and the frequency response functions and inertances between the seat and cab mounts, which were derived experimentally by the impact hammer test in static condition. The human sensitivity to vibration frequency was also taken into consideration for the calculation of ride vibrations at the 1/3 octave center frequencies in the frequency domain. Vibrations transmitted through rear cab mounts affected more significantly the ride vibration of tractor. The peak accelerations at the seat occurred at the frequencies of the engine and crank speed, and the frequency induced by tire lugs on the road transportation. It was found that the rear cab mounts should be improved in order to reduce the ride vibrations more effectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.216-223
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• 1999

This study was intended to determine the inertia , damping and stiffness properties of the cab-suspension of agricultural tractors by applying the direct system identification method (DSIM). Since the rigid and elastic modes of the cab-suspension are not likely to be separated clearly, direct application of the DSIM may result in large computation error. To solve such a problem, a method of locating mass center of the cab were determined by assuming the behavior of the cab-suspension is a rigid body motion. The dynamic parameters of the cab-suspension were then determined by applying the DSIM with the known coordinates of the mass center. The constraints of spatial matrices of the cab-suspension also make the algorithm for the DSIM perform better. The values of dynamic parameters determined by this method agreed well with those determined by the experiment.

• Journal of Biosystems Engineering
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• v.26 no.6
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• pp.509-516
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• 2001

This paper introduced some advantages of the time-frequency analysis of vibration and investigated, using the time-frequency transform, the characteristics of the transient motion of a tractor seat, which occurred during the tractor traversed over a rectangular obstacle on the flat surface. The characteristics of the short-time courier and wavelet transforms as time-frequency analysis methods were introduced and discussed to figure out which is more suitable to the analysis of the transient motions of agricultural tractors. Using each transform, transient vibration of a tractor seat was analyzed. Results of the analysis showed that the transient vibration of the seat was influenced by the natural frequencies of vertical mode of chassis, pitching mode of engine and pitching mode of cab of the tractor. The time sequence of the natural mode of tractor vibration was also revealed by the time-frequency analysis. The vibration path analysis by the time-frequency transform showed that the vibration energies transmitted from the front mounts to the seat were less than those from the rear mounts. The energy reduction ratios between the cab mounts and seat were also estimated to be about 72∼78%. The front mounts showed larger reduction than the rear mounts. However, the reduction difference between the right and left sides mounts was negligibly small. The short time Fourier transform was found to be a proper method for investigating the transient motions of farm machines and their effects on the ride vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1461-1466
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• 2000

This paper investigates the noise reduction scheme in tractor cabin by using various steps of experiment. The experiments were performed in the field as well as in the lab to facilitate the detail test procedure. Some of the test results were compared with computational results. Several noise sources and paths were identified including the engine compartment (cooling fan and timing gear cover), hydraulic system and its components (hoses, tubes and there mount) and structural characteristics of the cab, window, mounting bracket and machine frame including steps. Throughout the several design changes, cab noise level was reduced from 80.2dBA to 74.8dBA.

• Journal of Biosystems Engineering
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• v.23 no.4
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• pp.327-334
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• 1998

This work was intended to determine the optimum values of the cab suspension parameters by a simulation method in order to minimize the seat accelerations of agricultural tractors in the frequencies lower than 50Hz. A dynamic model of cab motions was developed and verified using a tractor excited over half-sine bumps on a concrete test road. A simulation program based on the model was also developed. A method was proposed to determine the optimum values of the suspension parameters. It was found that the natural frequencies of the cab and seat suspensions must be apart as far as possible until the sum of seat and cab accelerations is minimized, which also reduces the seat accelerations maximally.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2001.02a
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• pp.3-9
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• 2001

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.07a
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• pp.9-14
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• 2000