An examination was made of 19 different geometric shapes of warning labels, using the method of paired comparisons. Sixty-six college students viewed slides of all pairs of the shapes and each time selected the shape that was the preferred indicator of warning. An ordinal scaling method was used to evaluate the differences among the shapes. Results show that the triangle on its vertex was the preferred warning indicator among the shapes tested.

This research empirically evaluated the effects of handle shape and size on the hand's ability to resist or exert force in six directions. Thirty-six handles of four sizes and nine shapes were tested for maximum force exertion by male and female subjects. The results show that subjects were able to generate higher forces with different sizes and shapes of handles, depending upon the direction of force exertion. This suggests that handles that are associated with high forces on particular directional tests are probably suited for tasks that incorporate that particular type of force or movement; they may not be appropriate for other tasks that do not incorporate such movement.

This study examined the dexterity performance of 35 male and 35 female subjects at ambient temperatures of 1.7°C, 12.8°C, and 23.9°C. Subjects wore typical industrial worker apparel without gloves. The Purdue Pegboard, two pencil-point tapping tasks, an assembly task, and a fine manipulative task were used to measure the dexterity performance. Results indicate that after approximately 15 min of exposure there was no difference between performance at 12.8°C and 23.9°C, but there was a difference between performance at 1.7°C and 12.8°C as well as between performance at 1.7°C and 23.9°C. The decrement in performance at 1.7°C ranged from 0.3 to 15.7% when compared with performance at 23.9°C . In five of the 11 performance scores used, a difference due to gender was seen, with the males performing better on an assembly task and the females performing better on single-activity, repetitive tasks. At the higher ambient temperatures (12.8°C and 23.9°C), the average of the minimum finger skin temperature for males was from 0.57°C to 1.2°C higher than for females, whereas at 1.7°C there was no significant difference between the groups for minimum finger skin temperature.

The productivity of assembly lines is considerably affected by the health condition of assembly workers, and work-related musculoskeletal disorders (WMSDs) are common occupational diseases among assembly workers due to repetitive motions or heavy working loads. The conventional approaches to decreasing WMSD risks in the assembly lines include slowing the work-pace or applying job rotations. These adjustments usually focus on individual assembly workers at the station level but not the work allocation among the workers at the whole assembly line level, and thus may decrease the line productivity. To avoid these negative effects, some research started considering ergonomic characteristics at the line level, such as balancing ergonomic burdens by proper work assignment among workers. These previous studies incorporated physical grip demands or processing time overload into non-linear assembly line design problems, and used heuristic solution methods. This paper presents a methodology that explicitly integrates ergonomic measures for upper extremities into linear assembly line design problems. As the ergonomic measures, this research considers a guideline of Threshold Limit Value (TLV) from American Conference of Industrial Hygienists. Linear models are developed to link work-worker assignment to the measures of hand activity and hand-arm vibration. As productivity measures, conventional assembly line design criteria are considered, such as cycle time and the number of workers. These linear models allow ergonomic and productivity measures to be integrated as a mixed-integer programming model for assembly line design. In addition, these linearization methods can be generalized in order to incorporate ergonomic measures in tabulated forms into assembly line design problems.The analysis of the result shows the new model can effectively control the exposure levels in the upper extremity by proper work assignment compared to the conventional approaches, and does not decrease production rates considerably. This research also shows the potential to reduce the need of numerous task adjustments after assembly line design in traditional trial-and-error based assembly task adjustment. ACKNOWLEDGEMENTS

No abstract

No abstract

No abstract

This research evaluated two variables affecting the performance of tang guards in preventing injury due to the hand slipping forward on a knife handle: the radius of transition from the handle to the blocking portion of the tang and the height of the tang. For the radii evaluated, there was no effect for either men or women. The guard height, however, did have a significant effect for both genders. There is a height, different for men and women, that appears to be critical. Guard heights exceeding this critical height do not enhance the capability of the guard to prevent the hand from slipping. Guard heights less than this critical value are less capable of preventing slipping.