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- Volume 22, Issue 2, 2010
Ergonomics SA : Journal of the Ergonomics Society of South Africa - Volume 22, Issue 2, 2010
Volume 22, Issue 2, 2010
Author Candice ChristieSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 22 (2010)More Less
As this is the last edition of Ergonomics SA for 2010 it is appropriate to thank all of the people that make this journal possible. Firstly I would like to thank June McDougall who works tirelessly behind the scenes collating the paper submissions, the review documents and keeps me on my toes to ensure everything gets done. Secondly, the reviewers should get applauded; their names are listed at the back of this journal. The review process is a difficult and sometimes arduous task with no recognition or reward attached to it.
Author Fiona M. DonaldSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 22, pp 2 –13 (2010)More Less
Closed circuit television (CCTV) is used extensively to improve public safety and protect critical infrastructure in many countries. However, researchers have obtained mixed findings regarding its effectiveness. One possible explanation for this is that insufficient attention has been devoted to the human side of CCTV systems and detection processes, namely CCTV surveillance operators. These operators are required to sustain high levels of alertness and attention over extended periods of time, as with CCTV surveillance. Vigilance research has identified numerous factors that influence performance. However, these have typically been developed in isolation from the perceptual-cognitive processes involved in visual search and monitoring - key activities of operators. The aim of this paper was to integrate the factors into a holistic theoretical model of performance for CCTV operators, drawing on areas such as vigilance, human factors in system design, and perceptual-cognitive processes involved in visual search and monitoring. The model consists of five key components - the socio-political and industry contexts, organisational context, technological system and job design, operator processes and performance. It can be used as a basis for research regarding CCTV and for diagnosing performance issues in the operational context.
Source: Ergonomics SA : Journal of the Ergonomics Society of South Africa 22, pp 14 –32 (2010)More Less
Apparel manufacturing is a labour intensive assembly line process requiring significant amounts of repetitive, skilled manipulation. Various studies have identified relatively high frequencies of musculoskeletal discomfort among sewing machine operators. Poorly designed and maladjusted workstations contributed to such reported problems. A survey of sewing machine operators in South-western Nigeria showed that the workstations of the sewing machine operators, especially the sitting devices, were of various types designed without conforming to the human ergonomic requirements. All the tailors (sewing machine operators) used foot-operated sewing machines with the machine serving as work table. Fifty percent of them used stools as sitting devices, while 50% used chairs. Thirty-five percent of the stools and 43% of the chairs were padded. The tailors sat at the edge of their seats with severe flexion of the trunk and neck (> 450). Also, 91% flexed their knees forward approximately 1100 without the seat being able to tilt. Ninety-seven percent complained of neck-shoulder pain, 43% of upper arm pain, 3% of pain in the elbow and forearm area, 58% of chest pain and 2% of pain in the fingers. It is concluded that seat devices which are not ergonomically designed, impose various work postures on operators which may partly be responsible for their musculoskeletal disorders. Hence, the redesign of sitting devices with ergonomic characteristics is recommended.
Source: Ergonomics SA : Journal of the Ergonomics Society of South Africa 22, pp 33 –48 (2010)More Less
The functional capabilities of 37 male shovellers (25 - 58 years) during working spells in a shift were studied. They were selected following a random sampling technique stratified on the basis of their age. Prior to work anthropometric and cardiorespiratory variables were measured at the surface and VO2max was estimated by an indirect method following a standard step test protocol of Martiz et al. (1961). Heart rates and oxygen consumption during work were measured using Heart Rate Monitor and Oxylog II. Recovery heart rates were also taken after each spell of work by counting the pulse for the last 30 secs of each minute for three successive minutes to determine the Pulse Deceleration Index (Brouha 1960). Effective temperatures and WBGT were taken at regular intervals throughout the shift. The task was performed in two spells where shoveling and hand filling of coal contributed the maximum time in a spell followed by a longer non-volitional pause inbetween. In the present study, miners, irrespective of age maintained an intermediate shovelling rate of 12-14 scoops/min with an average scoop load of 5.5 - 6.5 kg. Heart rates of miners varied between 132 and 136 beats / min with a corresponding mean RCC of 56.6% - 67%. The latter showed significant difference (6.18; p<<0.001) along with net cardiac cost (65-70 beats/min) between two age groups (2.23; p<0.05). Deceleration of pulse between the shovellers was significant too (2.32; <0.05).The average working VO2 was 1.0-1.1 l/min corresponding to an energy expenditure of 5.2-5.6 Kcal/min. The relative aerobic strain (55.9-57.1%) did not vary significantly. Acceptable levels of physiological strain were surpassed frequently, and older workers experienced the greatest strain. The task appears to be 'heavy to very heavy' in nature according to the classification as suggested by Astrand (1986) and the prevailing environmental conditions have an impact on miner's work efficiency.
Source: Ergonomics SA : Journal of the Ergonomics Society of South Africa 22, pp 49 –65 (2010)More Less
Construction requires, inter alia, bending and twisting, working in awkward or cramped positions, reaching away from the body and overhead, repetitive movements, handling heavy materials and equipment, use of body force, exposure to vibration and noise, and climbing and descending.
The paper, which is based upon interviews conducted with workers using a structured questionnaire and a graphic inquiry, determined, inter alia: the hands, feet and lower back are mostly used; the lower and upper back are the anatomic regions where most pain is experienced, and handling heavy materials predominate among ergonomic problems encountered.
Tests conducted to investigate relationships determined mechanisation to be the intervention with the most potential to mitigate the current impact of the construction process on the human body.