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1

Evaluation of pliers’ grip spans in the maximum gripping task and sub-maximum cutting task

Kim D.-M., Kong Y. K.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 4

449--456

EN

A total of 25 males participated to investigate the effects of the grip spans of pliers on the total grip force, individual finger forces and muscle activities in the maximum gripping task and wire-cutting tasks. In the maximum gripping task, results showed that the 50-mm grip span had significantly higher total grip strength than the other grip spans. In the cutting task, the 50-mm grip span also showed significantly higher grip strength than the 65-mm and 80-mm grip spans, whereas the muscle activities showed a higher value at 80-mm grip span. The ratios of cutting force to maximum grip strength were also investigated. Ratios of 30.3%, 31.3% and 41.3% were obtained by grip spans of 50-mm, 65-mm, and 80-mm, respectively. Thus, the 50-mm grip span for pliers might be recommended to provide maximum exertion in gripping tasks, as well as lower maximum-cutting force ratios in the cutting tasks.

2

The relationship between hand anthropometrics, total grip strength and individual finger force for various handle shapes

Kong Y. K., Kim D.-M.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 2

187--192

EN

The design and shape of hand tool handles are critical factors for preventing musculoskeletal disorders (MSDs) caused by the use of hand tools. We explored how these factors are related to total force and individual finger force in males and females with various hand anthropometrics. Using the MFFM system, we assessed four indices of anthropometry, and measured total force and individual finger force on various handle designs and shapes. Both total force and individual finger force were significant according to gender and handle shape. Total grip strength to the handle shape indicated the greatest strength with D shape and the least with A shape. From the regression analysis of hand anthropometric indices, the value of R was respectably high at 0.608–0.696. The current study examined the gender and handle shape factors affecting grip strength based on the force measurements from various handle types, in terms of influence on different hand anthropometric indices.

3

The Effects of Co-ordinating Postures With Shoulder and Elbow Flexion Angles on Maximum Grip Strength and Upper-Limb Muscle Activity in Standing and Sitting Postures

Kong Y. K.

International Journal of Occupational Safety and Ergonomics

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2014

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Vol. 20, No. 4

595--606

EN

Eighteen co-ordination postures with shoulder flexion angles (0°, 45° and 90°) and elbow flexion angles (0°, 45° and 90°) in standing and sitting positions were evaluated to identify the effects of co-ordination postures on maximum grip strength and muscle activities of the upper limb in this study. Thirty-nine subjects were recruited and their maximum grip strengths were measured. According to the analysis of grip strength, grip strength was shown to be stronger in a standing posture (297.4 N) than in a sitting posture (274.6 N). In addition, grip strength (293.8 N) at 90° shoulder flexion angle was significantly higher than that at 0° and 45°shoulder angles. There was no statistically significant difference in grip strength from the effects of elbow angles in this study. The results of muscle activities for all muscle groups showed a similar trend with the results of grip strength associated with shoulder angles.

4

Postural Evaluation in a Poultry Farm for Broiler Chickens

Wang H., Kong Y. K., Jung M. C.

International Journal of Occupational Safety and Ergonomics

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2012

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Vol. 18, No. 1

67--75

EN

The goal of this study was to evaluate working postures in 9 operations of poultry farming for broiler chickens for 14 body segments with 4 categories, and for fingers with 14 categories. Overall, the farmers commonly bent almost all their body segments and used power grips. The operations of cleaning with water wand and inspecting chickens seemed light work because the farmers walked around most of their working time. The operations of detaching base from hanging feeder and attaching base to hanging feeder had the farmers continue squatting to handle the feeders close to the floor. The farmers also repeatedly bent their trunks in shoveling feces, unloading a box of chicks, and releasing chicks. A power grip was frequently observed due to using tools with round handles. Workplace design to raise working height would be necessary for a better working environment for broiler farmers.

5

Evaluation of Hook Handles in a Pulling Task

Kong Y. K., Freivalds A., Kim S. E.

International Journal of Occupational Safety and Ergonomics

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2005

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Vol. 11, No. 3

303--313

EN

To evaluate the effect of handle design characteristics on subjective ratings and pulling forces, meat-hook handles with various handle shapes, sizes, and hook positions were tested in a pulling task. Finger and phalange force data measured by force sensitive resistors and subjective ratings of discomfort were also evaluated. Generally subjects preferred 37-mm double frustum, 30-mm oval handles followed by 30-mm double frustum handles, 37-mm oval, and 45-mm double frustum handles. In the analyses of total pulling force, 37- and 45-mm double frustum handles showed less required pulling force than the others. The averages of finger force contributions to the total pulling force were 27.2, 28.1, 23.9, and 20.8% in order from index to little fingers. The average of phalange force contributions were 28.8, 33.6, and 37.6% for the distal, middle, and proximal phalanges, respectively. The findings illustrate that the pulling finger forces and subjective discomfort ratings were related to the handle shape as well as handle size.