• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.667-675
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• 2000

Force measuring devices should be calibrated to guarantee their test results. In order to establish the force standards in Korea, deadweight machines of 5 kN, 20 kN, 100 kN and 500 kN capacity and a hydraulic force standard machine of 2 MN capacity were installed at the Korea Research Institute of Standards and Science(KRISS). As heavy industries in Korea have been developed, we should measure large forces over 2 MN capacity precisely in industries. We developed a 10 MN force standard machine with built-in force transducers which is more compact and cheaper than hydraulic force standard machines which have been widely used as large force standards in most national metrology laboratories. Test results reveal that the relative expanded uncertainty of the force machine is less than 4.1 $\times$ 10-4 in the range of 1 MN-4.5 MN.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2213-2222
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• 1996

This paper presents the design process and evaluaation results of a two-axis force transducer for measuring flange reaction forces. A double-cantilever beam structure is used as a sensing element, and its optimal configuration is determined based on the derived strain equations to maximize the sensitivity and minimize the regid body displacements. To reduce the coupling errors between two-axis forces, strain distributions by finite elemetns analysis are utilized and the Wheaststone bridge cricuits composed of strain gages are built such that the output voltage should be zero, although strains of four strain gages are not zero. Calibration test shows that the two-azxis force transducer developed in this paper is useful in measuring flange reaction forces within the coupling error of 5.53%.

• Journal of Biosystems Engineering
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• v.18 no.4
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• pp.371-381
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• 1993

Threshing operation is performed by impact, compression and friction forces inside the thresher. These values should be appropriate to the crop condition to enhance the threshing and separating efficiency and to decrease the grain damage. To analyze the threshing process inside the rasp-bar type thresher, impact, friction and compression forces were measured using transducers with strain gage circuits. To measure the impact forces and friction forces between the rasp-bar and crop, full bridge strain gage circuit was built on the rasp-bar holder. To measure the compression forces and circumferential friction forces between the concave and crop, two sets of full bridge strain gage circuits were built on the T-type concave transducer. Threshing work of wheat crop with 12% of moisture content was performed at 3 levels of compression ratio and with 3 replications. Each transducer could not measure the exact forces continuously because the transducer oscillates with the forces. However they could measure maximum forces and force distribution according to the time. Average friction coefficients between crop and concave was 0.61 not showing any significant difference according to the compression ratio. Average acceleration of the crop in the cylinder appeared from $70.6m/s^2$ to $140.8m/s^2$ according to the compression ratio. The velocity of the crop at the exit of the cylinder appeared from 10.7m/s to 15.0m/s according to the compression ratio.