Occupational Ergonomics - Volume 1, issue 2

Authors: Chiou, Shiowyi | Bhattacharya, Amit | Lai, Chwan-Fu | Succop, Paul A.

Article Type: Research Article

Abstract: The objective of this study was to evaluate workers' ability to detect changes in postural balance using a short questionnaire -- the perceived sense of postural sway and instability (PSPSI) scale. Ratings of perceived sense of postural sway and instability for four simulated tasks were obtained from fifty-two healthy industrial workers and compared with objective measurements determined by a strain gauge type force platform. The simulated tasks were performed under various experimental conditions that may influence postural stability. It was found that subjects were able to perceive the changes in postural sway and instability due to the modification in peripheral …vision, environmental lighting, workload, and surface firmness, as reflected by their PSPSI ratings. Results from this study indicate that the PSPSI scale is a promising tool, which provides a simple and valid method to evaluate the potential for loss of balance in the workplace. Show more

Keywords: Posture, balance, stability, perceived sense of postural instability

DOI: 10.3233/OER-1998-1201

Citation: Occupational Ergonomics, vol. 1, no. 2, pp. 81-93, 1998

Authors: Imbeau, Daniel | Paques, Joseph-Jean | Bergeron, Sylvie | Bourbonnière, Réal

Article Type: Research Article

Abstract: Performance of experienced crane operators in stopping rotational movements of a crane platform was compared with that of an automatic braking system. Sixteen certified crane operators performed boom movements towards a segment of a typical power line using a 100 tons lifting capacity crane equipped with a fixed-length 18 m long boom, a single lifting cable, and hard ball hook. The 18 m boom was later replaced with a 49 m boom to vary crane geometry and motion response. In all trials, a 1500 kg (3500 lb) load was hooked to the lifting cable. In critical operating conditions, the control …input strategy used by the experienced crane operators could yield a stopping angle comparable to that of the automatic braking system. However, when compared with the automatic braking system, the operators had a better control on the oscillations of the load during the stopping maneuver. The data collected in this experiment were used to specify two key parameters in the design of a crane movement limiting device. Show more

Keywords: Power lines, crane, electrocution, movement limiting devices, safety equipment

DOI: 10.3233/OER-1998-1202

Citation: Occupational Ergonomics, vol. 1, no. 2, pp. 95-105, 1998

Authors: Al-Eisawi, Khaled W. | Kerk, Carter J. | Congleton, Jerome J.

Article Type: Research Article

Abstract: This study evaluated wrist strength limitations to manual exertion capability in two-dimensional static biomechanical modeling. The researchers hypothesized that wrist strength does not limit manual exertion capability - an assumption commonly made in many strength biomechanical models. An experiment was conducted on 15 right-handed males of college age. Isometric wrist flexion strength was measured at two elbow angles: 90 degree and 135 degree and in two wrist positions: neutral and 45 degree extended. Isometric wrist radial deviation strength was measured at the same two elbow angles and in two wrist positions: neutral and 30 degree ulnarly deviated. Minimum wrist strength …limits for which wrist strength does not limit maximal moments about the elbow in manual hand exertions were calculated and compared to their corresponding measured wrist strength moments using paired t-tests. In general, wrist strength was non-limiting. However, wrist flexion strength in the 45 degree extended wrist posture was limiting. Weak-wrist subjects showed more wrist strength limitations than strong-wrist subjects. Show more

Keywords: Biomechanical models, isometric strength, wrist flexion strength, wrist radial deviation strength, elbow flexion strength

DOI: 10.3233/OER-1998-1203

Citation: Occupational Ergonomics, vol. 1, no. 2, pp. 107-121, 1998

Authors: Hernandez, Luz | Genaidy, Ash | Davis, Sue | Guo, Lin | Alhemoud, Ali

Article Type: Research Article

Abstract: This study was conducted to determine whether the activities performed by fourteen registered nurses subjected the different body joints to varied levels of musculoskeletal strain. While the present study confirmed the presence of significant lower back problems among nurses, the findings strongly suggest that nurses experienced significant musculoskeletal strain in other body parts/joints. In general, the lower back, neck, shoulder and wrist/hand recorded the highest scores in terms of frequency and severity of musculoskeletal strain. Discomfort increased significantly during the course of time for all body parts. A practical method was proposed for the evaluation of musculoskeletal discomfort on the …basis of the Borg scale. The 0-2 range is suggested as a green zone where no action is required. The 3-5 is presented as a yellow zone where caution should be in place and an action plan should be formulated to monitor the jobs in question in the intermediate and long terms. This zone is preserved for cumulative-based ergonomic problems. Finally, the 6-10 range should be regarded as a red zone where an immediate action should be in place because musculoskeletal troubles are around the corner and could occur any time. Again, the red zone is expected to cover acute-based ergonomic deficiencies. Show more

DOI: 10.3233/OER-1998-1204

Citation: Occupational Ergonomics, vol. 1, no. 2, pp. 123-133, 1998

Authors: Krumwiede, Dennis | Konz, Stephan | Hinnen, Paula

Article Type: Research Article

Abstract: The purpose of this study was to evaluate 6 specific standing surfaces (a concrete surface and 5 different floor mat styles). The subjects stood for one hour on each of 6 different surfaces. Each subject completed a comfort evaluation form at 15-minute intervals indicating on a scale of 1 to 10 the discomfort they were experiencing. The most desirable surface was chosen from a statistical analysis and a qualitative selection made by each subject. Mat preference was higher for more compressible mats.

Keywords: Standing comfort, floor mats

DOI: 10.3233/OER-1998-1205

Citation: Occupational Ergonomics, vol. 1, no. 2, pp. 135-143, 1998

Authors: Foster, Rosemary S. | Adams, Laurence P. | van Geems, Barbara A. | Bridger, Robert S.

Article Type: Research Article

Abstract: A laboratory study was conducted in order to investigate postural adaptations to constrained standing during VDT work sessions. Standing postures were observed in six different workspaces which were designed using combinations of foot position (which was either constrained or unconstrained) and varied VDT screen height. Subjects at work were recorded stereophotogrammetrically and postural variables were obtained in three dimensions. Postural adaptation was found to be significantly asymmetrical with the weight carried on the left. The constrained foot position resulted in more bending forward from the hip. Raised screen height resulted in decreased neck flexion and increased hip flexion. It was …concluded that recommendations for seated VDT work are not always applicable to standing VDT work. Show more

Keywords: Standing, posture, workspace design, VDT

DOI: 10.3233/OER-1998-1206

Citation: Occupational Ergonomics, vol. 1, no. 2, pp. 145-156, 1998