• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.2
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• pp.39-47
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• 2020

Postural stability can reduce the likelihood of critical slip and fall accidents in workplaces. The present study aimed to analyze the effect of shoes type on the ability of postural control during quiet standing. The effect of workload on the body balance was also of primary concern. Thirteen healthy male undergraduate students participated voluntarily in the experimental study. Standing on a force plate with wearing slippers, sports shoes, or safety shoes, two-axis coordinate on subjects' center of pressures (COP) was obtained in the two levels, rest and workload. For the workload level, subjects performed treadmill exercise to reach the predetermined level of physical workload. By converting the position coordinates of COPs, the postural sway length in both anterior-posterior (AP) axis and medio-lateral (ML) axis was assessed. ANOVA results showed that, in AP direction, wearing slippers significantly increased the postural sway length compared to wearing sports shoes or safety shoes. No significant difference in the mean sway length in AP axis was observed between sports shoes and safety shoes. In ML direction, both the workload and the shoes type did not significantly affect the mean length of postural sway. However, the postural sway length increased marginally with the slippers especially during the workload condition. This study explains wearing slippers may interfere with the ability of postural control during quiet standing. Physical workload decreases the ability of postural stability further.

• Journal of Biosystems Engineering
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• v.38 no.2
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• pp.163-170
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• 2013

Purpose: The purpose of this study is to provide analysis of physiological, biomechanical responses occurring from the operation to lifting or twist lifting task appears frequently in agricultural work. Methods: This study investigated the changes of physiological factors such as heart rate, heart rate variability (HRV) and biomechanical factors such as physical activity and kinetic analysis in the task of twisting at the waist while lifting. Results: Heart rates changed significantly with the workload. The result indicated that the workload of 2 kg was light intensity work, and the workload of 12 kg was hard intensity work. Physical activity increased as the workload increased both on wrist and waist. Besides, stress index of the worker increased with the workload. Dynamic load to herniated discs was analyzed using inertial sensor, and the angular acceleration and torque increased with the workload. The proposed measurement system can measure the recipient's physiological and physical signals in real-time and analyzed 3-dimensionally according to the variety of work load. Conclusions: The system we propose will be a new method to measure agricultural workers' multi-dimensional signals and analyze various farming tasks.

• Journal of Biomedical Engineering Research
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• v.32 no.4
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• pp.328-335
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• 2011

For human factor engineering and wearable robot design, the quantitative assessment of physical workload is needed. Through measuring the surface EMG (sEMG) and analysis, the physical workload in overhead lifting posture is presented in quantitative manner. By normalizing sEMG activities with maximal voluntary contraction (MVC), the inter-subject variability is reduced. In all muscles, %MVC increased as the weight of lifting object increases. In anterior deltoid muscle, the %MVC was 3-4 times higher than the other muscles which imply that this muscle performs the major role in the overhead lifting posture. In fatigue analysis, %MVC and the mean frequency in muscle of anterior deltoid changed markedly when compared with other muscles. Through the suggested procedures and analysis, the physical workload for a specific posture can be represented in quantitative way but the clinical meaning for the value should be investigated further.

• Safety and Health at Work
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• v.6 no.3
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• pp.192-199
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• 2015

Background: Overweight, obesity, and cardiovascular disease risk factors are prevalent among firefighters in some developed countries. It is unclear whether physical activity and cardiopulmonary fitness reduce cardiovascular disease risk and the cardiovascular workload at work in firefighters. The present study investigated the relationship between leisure-time physical activity, cardiopulmonary fitness, cardiovascular disease risk factors, and cardiovascular workload at work in firefighters in Hong Kong. Methods: Male firefighters (n = 387) were randomly selected from serving firefighters in Hong Kong (n = 5,370) for the assessment of cardiovascular disease risk factors (obesity, hypertension, diabetes mellitus, dyslipidemia, smoking, known cardiovascular diseases). One-third (Target Group) were randomly selected for the assessment of off-duty leisure-time physical activity using the short version of the International Physical Activity Questionnaire. Maximal oxygen uptake was assessed, as well as cardiovascular workload using heart rate monitoring for each firefighter for four "normal" 24-hour working shifts and during real-situation simulated scenarios. Results: Overall, 33.9% of the firefighters had at least two cardiovascular disease risk factors. In the Target Group, firefighters who had higher leisure-time physical activity had a lower resting heart rate and a lower average working heart rate, and spent a smaller proportion of time working at a moderate-intensity cardiovascular workload. Firefighters who had moderate aerobic fitness and high leisure-time physical activity had a lower peak working heart rate during the mountain rescue scenario compared with firefighters who had low leisure-time physical activities. Conclusion: Leisure-time physical activity conferred significant benefits during job tasks of moderate cardiovascular workload in firefighters in Hong Kong.

• Physical Therapy Korea
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• v.16 no.1
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• pp.42-51
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• 2009

The purpose of this study was to develop a checklist of risk factors for quantitative assessment of musculoskeletal complaints in shipbuilding workers. A key point was to develop comprehensive a checklist including the worker's physical ability, as ergonomic and workload factors. ln the first, through correlation analysis between musculoskeletal complaints and physical abilities in shipbuilding workers, risk factors related to physical abilities were selected. In the second, after the development of a checklist was composed of physical, ergonomic and workload factors, factor analysis was used to test the validity of the developed checklist. Each factors selected finally showed that physical factors were hand grip strength, spinal curvature, and flexibility (sit to reach), ergonomic factors were posture, total exposed time, duration, and force of working, and workload factors were physical and psychological workload perceived by worker. The results showed that musculoskeletal complaints was associated with physical abilities (p<.05). The developed checklist had a reliability of .761 (Cronbach=.761) and a validity and explanation of 54.9%. The criterion of management was classified in 4 stages by relative weights of each factor. It is suggested that active intervention is needed to reduce musculoskeletal complaints in workers with more than a 14.31 score.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.25-34
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• 2009

A cross-sectional study was conducted to assess the association between musculoskeletal workload and psychosocial job stress variables from 100 employees from a cable making industry. It was found that the employees who had to do musculoskeletal hazardous tasks suffered higher psychosocial stress in 'decision latitude', 'job insecurity' and 'psychological job demands' also. The employees with higher level of psychosocial job stress in 'psychological job demands' and 'score of the "type A" personality' responded that they had higher 'physical job demands' from the task irrespective of its musculoskeletal hazardousness. These results confirm that musculoskeletal workload were associated with both physical and psychosocial work factors. Attention should be paid to psychosocial work factors along with physical workload to prevent musculoskeletal disorders in the manufacturing industries.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.45-59
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• 2007

The operating tasks of overhead crane have caused undue stress to the operators from physical, mental, and environmental workload. Existing workload assessment models for musculoskeletal disorders such as OWAS, RULA, and QEC have limited applicability to the crane operating tasks because they focus mainly on physical factors and do not consider the relative importance of each factor. The present study was to develop a workload assessment model customized to overhead crane operation, following a systematic process: (1) analyzing task characteristics, (2) selecting workload factors, (3) developing assessment methods, (4) establishing action levels, and (5) computerizing the assessment model. Based on literature review, worksite survey, and focus group interview, 4 physical factors (awkward posture, static posture, repetitive motion, and excessive force), 6 mental factors (visual demand, auditory demand, task complexity and difficulty, time urgency, work schedule related stress, and safety related stress), and 4 environmental factors (noise, vibration, dust, and temperature) were selected and their rating scales and relative weights were determined. Then, based on the workload assessment results of 8 overhead cranes operated at different workplaces, the action levels of each factor category were established. Finally, the crane operation assessment model was computerized for effective analysis and report preparation. The present approach is applicable to develop a customized workload assessment model for an operating task under consideration.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.137-147
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• 2007

Dentists are known to be highly exposed to the musculoskeletal disorders (MSD). The present study investigated the prevalence of MSD among Korean dentists and association between their MSD and physical workload. In addition, work-related causes of high physical workload were identified and needs of dentists were collected for improvement of dental instrument and environment. Four types of questionnaires including the Nordic questionnaire were used to investigate body troubles, physical workload, causes of physical workload, and improvement priority of dental components. A total of 104 dentists in Seoul were participated in the survey. Neck trouble (82%) was the most prevalent in the participated dentists and shoulder (68%) and low back trouble (56%) followed, while low back trouble was reported to be most common in previous western studies. The body troubles were related to the physical workload of the corresponding body parts, although they were not associated with personal characteristics. Most dentists selected 'to keep direct view inside patient's mouth' and 'no support of the hand with dental instruments' as causes of awkward and strenuous work postures. They wanted design improvement for some components in their operating room such as operating light and arrangement of workplace.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1242-1242
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• 2022

Annually, several construction workers fall ill, are injured, or die due to heat-related exposure. The prevalence of work-related heat illness may rise and become an issue for workers operating in temperate climates, given the increase in frequency and intensity of heatwaves in the US. An increase in temperature negatively impacts physical exertion levels and mental state, thereby increasing the potential of accidents on the job site. To reduce the impact of heat stress on workers, it is critical to develop and implement measures for monitoring physical exertion levels and mental state in hot conditions. For this, limited studies have evaluated the utility of wearable biosensors in measuring physical exertion and mental workload in hot conditions. In addition, most studies focus solely on male participants, with little to no reference to female workers who may be exposed to greater heat stress risk. Therefore, this study aims to develop a process for objective and continuous assessment of worker physical exertion and mental workload using wearable biosensors. Physiological data were collected from eight (four male and four female) participants performing a simulated drilling task at 92oF and about 50% humidity level. After removing signal artifacts from the data using multiple filtering processes, the data was compared to a perceived muscle exertion scale and mental workload scale. Results indicate that biosensors' features can effectively detect the change in worker physical and mental state in hot conditions. Therefore, wearable biosensors provide a feasible and effective opportunity to continuously assess worker physical exertion and mental workload.

• Journal of Preventive Medicine and Public Health
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• v.41 no.5
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• pp.331-338
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• 2008

Objectives : The purpose of this study was to measure the workload of home visit care activities and their relative values. This study examined also factors that affect the workload of home visit care activities. Methods : The participants of this study were 126 home-helpers of 50 home visit care agencies at the 2nd Long-term Care Insurance Demonstration Project. The workload of home visit care activities was divided into total work and four dimensions ; physical efforts, mental efforts, stress and time. Home visit care activities consisted of four categories with 24 items. We used magnitude estimation method to measure their relative values of the four dimensions. The participants answered the relative values of each activities based on the reference service. We used the activity for supporting their elderly's evacuation as the reference service. Results : Most of the respondents were over 40 years old female. They consumed most their time supporting elderly's going out. They consumed their highest physical, mental efforts, and stress for activities of coping with emergency situation. The Pearson correlation coefficients showed significant relationships between workload and each dimensions. This study showed that all four dimensions are statistically significant predictors of workload of home visit care activities. Also, we found that the home-helper's career affects the workload of home visit care activities. Conclusions : The workload of home visit care activities could be explained by physical efforts, mental efforts, stress and time.