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Visual Costs of the Inhomogeneity of Luminance and Contrast by Viewing LCD-TFT Screens Off-Axis

Ziefle M., Groeger T., Sommer D.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 4

515--525

EN

In this study the anisotropic of TFT-LCD (Thin-Film-Transistor-Liquid Crystal Display) screens were examined. Anisotropy occurs as the distribution of luminance and contrast changes over the screen surface due to different viewing angles. On the basis of detailed photometric measurements the detection performance in a visual reaction task was measured in different viewing conditions. Viewing angle (0°, front al view; 30°, off-axis; 50°, off-axis) as well as ambient lighting (a dark of illuminated room) were varied. Reaction times and accuracy of detection performance were recorded. Results showed TFT’s anisotropy to be a crucial factor deteriorating performance. With an increasing viewing angle performance decreased. It is concluded that TFT’s anisotropy is a limiting factor for overall suitability and usefulness of this new display technology.

2

The Effects of the Level of Alertness During the Rest Period on Subsequent Performance

Hirose A., Nagasaka A.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 4

479--490

EN

The aim of this study was to examine how to take an effective rest to prevent a decline in alertness at work. The relationship between alertness during the rest period and subsequent task performance were investigated. The electroencephalogram (EEG) during the rest period was classified into 3 types, and these types had a significant effect on performance after the rest period. Type 1 (increasing in theta, alpha 2, and beta 1 power) was the best one for carrying out the task, whereas performance gradually declined in Type 3 (no change in EEG activity). In the case of Type 1, the method that would relieve sleep inertia bad a more positive impact on performance after the rest period.

3

Symptoms and Clinical Findings From the Musculoskeletal System Among Operators at a Call Centre in Sweden-A 10-Month Follow-Up Study

Toomingas A., Nilsson T., Hagberg M., Hagman M., Tornqvist E. W.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 4

405--418

EN

The musculoskeletal health among 57 operators at 1 call centre in Sweden was studied with 10 monthly follow-ups, parallel to a reference group of 1,226 professional computer users in other occupations. Operators at this call centre were more symptom-loaded than the other professional computer users in spite of their younger age and shorter exposure to computer work. Symptoms were long-lasting or recurrent. Muscle tenderness and nerve affections in the neck-shoulder region were the most common specific findings and diagnoses at medical examination of incident symptom cases. More extensive studies should be done on the working conditions and health status among call centre workers.

4

Sitting Posture, Postural Discomfort, and Visual Performance: A Critical View on the Interdependence of Cognitive and Anthropometric Factors in the VDU Workplace

Ziefle M.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 4

503--514

EN

The study focuses on individual and standard visual display unit (VDU) workplaces with respect to performance and muscular load. Three different work settings were realized: The workplace was either adjusted to individual preferences or to the European standard. The third condition mirrored exactly the individual setting, however participants were told that it was set according to another standard. Dependent variables were visual performance in a search task, the rated muscular load, and individual preferences. Results show that both individual work settings yielded a superior performance as compared to the standard. However, performance and muscular comfort improved when participants knew they had adjusted the workplace. Apparently, VDU users follow a intuitive rationale adjusting their work setting minimizing muscular load and optimizing performance.

5

Reducing Musculoskeletal Discomfort: Effects of an Office Ergonomics Workplace and Training Intervention

Robertson M. M., O’Neill M. J.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 4

491--502

EN

Effects of an office ergonomics workplace and training intervention on workers’ knowledge and self-reported musculoskeletal pain and discomfort were investigated. An instructional systems design process was used to develop an office ergonomics training program and the evaluation tools used to measure the effectiveness of the training program on workers’ office ergonomics knowledge and skills. It was hypothesized that the training and workplace intervention would allow the worker to more effectively use their workplace through increased office ergonomics knowledge and skills. Following the intervention, there was a significant increase in workers’ office ergonomics knowledge and awareness. Self-reported work-related musculoskeletal disorders significantly decreased for the group who had a workplace change and received ergonomic training relative to a workplace change-only group and a no intervention control group.

6

A New Approach to the Mouse Arm Syndrome

Ullman J., Kangas N., Ullman P., Wartenberg F., Ericson M.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 4

463--477

EN

OBJECTIVES: The study validates a new computer mouse concept. The tested device is a small mouse with a pivoting pen-shaped handle. The hypothesis behind the design is the assumptions that the pen grip requires less static tension than the normal mouse grip and that fine-motor, high precision tasks normally are done with finger movements with forearm at rest. METHODS: Four muscles were monitored with electromyography (EMG) during work with a new mouse and with a traditional mouse. RESULTS: EMG activity was significant lower, in M. pronator teres - 46%, M. extensor digitorum - 46%, M. trapezius - 69%, and M. levator scapulae - 82%, during work with the new mouse as compared to the traditional mouse. CONCLUSION: Altering the design of the computer mouse can significantly reduce muscular tension.

7

Three-Dimensional Lifting Model For Non-Homogeneous Loads

Gilad I., Boughanim D.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

511--524

EN

A 3-dimensional model and analysis methodology is suggested for treating lifting tasks when unbalanced loads are involved. The paper describes the biomechanical equations that are coupled with the worker’s posture geometry, to address a practical problem of non-symmetric lifting. The analysis has a dominant biomechanical modeling scope, as it contains a breakdown of the internal lifting forces resulting from posture and external loads acting on the body. The load model represents the acting forces due to unbalanced lifting, which is commonly found in industrial situations. The suggested model allows the user to simulate the influence of the practical load distribution, aiding safe design of a lifting job.

8

The Relationships Between Biomechanical and Postural Stresses, Musculoskeletal Injury Rates, and Perceived Body Discomfort Experienced by Industrial Workers: A Field Study

Stuebbe P., Genaidy A., Karwowski W., Kwon Y. G., Alhemood A.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 2

259--280

EN

A combination of archival, subjective, and observational field data collection methods were used to investigate the relationship between biomechanical and postural stresses, and the resulting physical strain experienced by industrial workers of a packaging plant. Assessment of physical strain was based on the number and incidence rate of Occupational Safety and Health Administration (OSHA)-reportable injuries that were recorded over a period of 27 months, and based on the self-reported ratings of perceived body discomfort. Both the biomechanical and postural stresses correlated with the musculoskeletal injury rate. The results illustrate the usefulness of postural and biomechanical analyses for assessing the risk of injury in industry.

9

Lifter, a Computerized Lifting Analysis Technique

Gilad I., Boughanim D.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

525--537

EN

A computer driven technique to analyze lifting forces, in non-homogeneous load situations, is described and tested. Analysis is based on a dynamic algorithm aimed to evaluate unconstrained lifting posture and non-homogeneous content of loads. For inputs we use actual geometrical body postures in the form of 3-dimensional co-ordinates obtained from pictures taken at a work site. The outputs show a good match between the findings and pre-study assumptions for balanced and non-balanced load lifting practice. The results of the experiments show a good degree of correlation with results reported by researchers for symmetrical lifting tasks and with National Institute for Occupational Health (NIOSH) lifting guidelines. It is believed that the technique can serve as the proper choice for industrial and safety analysts of lifting activities.

10

Ergonomics in Practice: Physical Workload and Heat Stress in Thailand

Yoopat P., Toicharoen P., Glinsukon T., Vanwonterghem K., Louhevaara V.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 1

83--93

EN

This study consists of assessments of the thermal environment and physiological strain in tasks associated with airport, construction, and metal jobs. The number of male and female participants was 108. Environmental heat stress was evaluated with the WBGT index. Physiological strain was evaluated by the relative cardiovascular load (%CVL) based on the measurements of heart rate. Also the increase of body temperature, weight loss, and perceived discomfort were determinated. At work sites the assessments lasted for 2 to 4 hrs for each participant. The mean physiological strain exceeded the level of 30%CVL. Severe peaks (over 60%CVL) were observed in specific tasks being in agreement with perceived discomfort ratings. The increase of body temperature and weight loss in most cases remained within acceptable limits. For the most strenuous tasks, various ergonomic improvements were developed in consultation with workers and managers.

11

Driver Workload Response to In-Vehicle Device Operations

Jerome C. J., Ganey H. C. N., Mouloua M., Hancock P. A.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

539--546

EN

A central concern of Intelligent Transportation Systems (ITS) is the effect of in-vehicle devices (e.g., cell phones, navigation systems, radios, etc.) on driver performance and safety. As diverse and innovative technologies are designed and implemented for in-vehicle use, questions regarding the presence and use of these devices assume progressively greater importance. Further concerns for advanced driver training require us to develop and validate reliable and effective procedures for assessing such effects. This work examines a number of candidate procedures, in particular the evaluation of change in cognitive workload as a strategy by which such goals might be achieved.

12

Combining Psychophysical Measures of Discomfort and Electromyography for the Evaluation of a New Automotive Seating Concept

Kolich M., Taboun S. M.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

483--496

EN

The purpose of this study was to determine if the advantages and disadvantages of a new automotive seating concept, known as the micro-adjuster control system, could be reliably evaluated using both a physiological assessment technique (i.e., electromyography [EMG]) and a subjective questionnaire. The results indicate that psychophysical measures of discomfort and the root mean squared (RMS) activity of the EMG are statistically related, r (8) = –.788, p=.020. More specifically, subjective perceptions of comfort were found to improve with decreasing levels of muscle activity. This implies that seat comfort can be evaluated on the basis of physiological as well as subjective responses to prolonged driving. This finding should drastically improve automobile seat design efforts.