| Summary: | 碩士 === 明志科技大學 === 工業工程與管理研究所 === 101 === This study attempts to psychophysically determine the maximum acceptable weight of lift (MAWL) for irregular object by twelve male participants because the determined MAWL would be valuable for manual handling design and employee screening. This study therefore employed the psychophysical approach to collect individual’s MAWLs under various task combinations of 3 lifting ranges (floor to knuckle, FK; floor to shoulder, FS; and knuckle to shoulder, KS), 3 lifting frequencies (one time maximum and 1,4 lifts/min), and 2 hand conditions (with/without gloves). The participant’s heart rate (HR), compression forces on L5/S1 disc, and the subjective discomforts on body regions were measured once their MAWLs were determined. Result show that MAWL, HR and L5/S1 disc compression forces were significantly affected by the lifting frequencies and the ranges (all p<0.001), whereas the hand condition did not influence the MAWL. Participants exhibited relatively low MAWL comparison with that of previous studies, especially in infrequent tasks. As expected, the MAWL decreased with an increase in lifting frequencies. The HR had reached the level of heavy work (110-130 beat/min) when lifting with the frequency of 4 lifts/min. The L5/S1 disc compression forces in FK and FS tasks were higher than the Action Limit (AL) as indicated by NIOSH lifting guides. Lifting frequency also affected the perceived discomforts of the participants (p<0.05), which indicated that lifting frequency would be a dominant factor for the determined MAWL, rather than other task variables in the study. Result of a multiple stepwise regression shows that some anthropometric data (e.g., chest circumference) as well as isoinertial and isometric strengths, were able to account for the percent of variance of the determined MAWL in ranging from 83.22% to 95.31%. These factors can be considered as the better predictors for MAWL prediction.
|
|---|
