International Journal of Industrial Ergonomics最新文献

Objective

To investigate the influence of wrist position and torque level on lower arm flexor muscle fatigue.

Background

Work-related musculoskeletal health risks at the wrist joint may depend on joint position and torque level, as proposed by ergonomic workplace assessment tools. As empirical data are scarce, muscle fatigue, as proxy of work-related musculoskeletal health risks, can be used to explore this assumption.

Method

18 healthy participants performed fatiguing isometric wrist flexion contractions in three wrist positions (40° flexion, 0° neutral position, and 40° extension) and torque levels (10, 20, 40% of the maximum voluntary contraction). Electromyographic signs of fatigue were analyzed in the flexor carpi radialis (FCR) and flexor digitorum superficialis (FDS) muscles.

Results

Muscle fatigue was dependent on torque level and wrist position and differed between muscles. Signs of fatigue were more evident at higher torque levels for both muscles. While fatigue signs in FCR were not clearly associated with wrist position, the FDS fatigued more during wrist flexion. An interaction effect between torque level and wrist position was not observed.

Conclusion

Higher torque levels induce greater signs of local muscle fatigue in wrist flexor muscles, and a 40° wrist flexion triggers fatigue, while 40° wrist extension does not. Our data do not support the assumption of increased risk in greater wrist angles in any direction by prevailing ergonomic risk assessments.

Relevance to industry

People with work-related wrist flexor effort may be at increased risk of musculoskeletal disorders when higher torques are applied and flexed wrist positions are required.

Checklist Individual Strength (CIS) is a widely used questionnaire to measure a level of the chronic fatigue syndrome. The purpose of this study was to translate CIS into Korean and evaluate the reliability and validity of a Korean version of CIS (K–CIS) for the Korean working age population. In the first experimentation of the study, four bilingual translators participated to translate CIS using a cross-cultural translation method. Then, a concurrent validity of K–CIS with the original CIS was evaluated by 28 bilingual participants. With a statistical analysis, it was confirmed that K–CIS and CIS were linguistically equivalent. In the second experimentation, 172 participants from various universities, industries, and small businesses assessed K–CIS along with two other representative fatigue questionnaires such as mKCFQ11 and SF-36. Our result of the statistical analysis using Cronbach's α, confirmatory factor analysis, inter-scale correlation, and correlation with other questionnaires showed that K–CIS was a valid fatigue questionnaire. Therefore, we conclude that K–CIS can be an effective tool to evaluate a severity of fatigue in the Korean working age population.

Work-related musculoskeletal disorders (WRMSDs) lead to fatigue and decreased productivity in workers, resulting in the need for many affected individuals to seek medical treatment annually. Beekeepers, like other agricultural workers, are susceptible to WRMSDs due to the continuous demands of their work and the repetitive movements involved. Thus, the objective of this study is to determine the prevalence of WRMSDs and assess the level of risk associated with different postures among beekeepers to improve their musculoskeletal health. To achieve this, a cross-sectional study was conducted involving 33 beekeepers, consisting of two stages. Firstly, the Nordic Questionnaire was utilized to assess the prevalence of WRMSDs. Subsequently, the Ovako Working Posture Analysis System (OWAS) was employed to analyze and categorize the riskiest postures into four levels of corrective measures. The findings indicate that the most commonly affected areas were the back (51.5%) and waist (45.4%). The occurrence of WRMSDs in various body regions was significantly associated with the beekeepers’ years of experience and weekly working hours. Additionally, the prevalence of neck and back pain was significantly related to their body mass index (BMI). The OWAS postural analysis revealed that the back (36.75%) and arm (21.08%) regions required corrective measures as soon as possible (level III), while the back (26.47%) and legs (14.70%) fell under the category of corrective measures needed in the near future (level II). Combining the postural analysis results, 28.43% were classified as Action Levels (AL) II, 37.73% as level III, and 0.98% as level IV. This study demonstrates that WRMSDs are relatively common among beekeepers, primarily due to their extensive work experience and the adoption of awkward postures during their tasks. As a result, recommendations regarding ergonomics and physiotherapy are provided to alleviate pain and reduce the strain on critical postures.

The occurrence of coal mine accidents is closely related to human factors. Six-hundred eighty five coal mine accident reports were analyzed to identify risk factors for coal mine accidents. A total of 29 human factors were classified from three levels of supervision-management-production using the improved HFACS (Human Factors Analysis and Classification System) model, and the degree of clustering of human factors was verified by complex networks. Then, the 29 human factors were classified into four categories by K-Means clustering analysis, namely subjective corrective accident human factors, perceived corrective accident human factors, associated corrective accident human factors, and critical corrective accident human factors, and control suggestions were proposed for different categories. Finally, the interface of the supervision-management-production-based coal mine employee control system was designed in order to provide a solid theoretical basis for the subsequent system development and its application in specific coal mines. This study can provide new ideas for the study of human factors of coal mine accidents and help coal mine enterprises to strengthen the control of human factors.

This study aimed to quantitatively evaluate the factors that influence variations in psychological stress caused by seat vibrations. We employed the center of gravity sway measurements, a metric extensively studied in the realm of motion sickness. Our approach encompassed experiments and analyses to measure whole-body vibrations, scrutinize physiological responses, and assess the center of gravity sway. Our findings highlighted that the seat's vibration characteristics and their transmission to the occupant varied according to the occupant's center of gravity sway traits. We formulated a hypothesis to elucidate the correlation between the psychological stress induced by seat vibration and the nuances of the center of gravity sway. This theory was substantiated through correlation analysis. Involving 20 subjects, correlation analysis results showed a correlation between the peak strength of the PSD for the center of gravity sway's time variation around 2 Hz, the transmitted vibration, and the psychological stress deduced from electroencephalography (EEG) readings.

Building Information Modelling (BIM) is a process, often mentioned as an enabler of various benefits within Architecture – Engineering – Construction (AEC), of creating and managing information for a built asset. Despite the potential benefits associated with BIM, the use seems to have been relatively inefficient. One explanation may be the lack of system perspective in the implementation and use of BIM. The aim of this study was to map critical factors influencing the use of BIM based on existing research, including interactions among the three subsystems human, technology and organization. A scoping review was performed analyzing 46 included articles. The results showed that BIM is a holistic and social system, that the technology itself is insufficient, and that the acceptance of BIM is a significant critical factor for its efficient implementation and use. The research on how humans interact with the technology of BIM, and how the organization can facilitate those interactions, is however limited.

Relevance to industry

Learnings from this study include that the AEC industry, by approaching BIM as a holistic and social system and recognizing the role of the individual user, can add another piece of the puzzle to achieving the effective use of BIM.

Introduction

Firefighters repeatedly encounter traumatic and stressful events while on duty, leading to mental disorders such as post-traumatic stress disorder symptoms (PTSS). This disorder can affect the rate of cognitive failures (CFs) and thus increase the probability of human error, unsafe behaviors, and accidents. The present study was conducted to investigate the direct and indirect effects of trauma load on the rate of CFs in firefighters and to investigate the mediation effect of PTSS and the moderation effect of resilience, neuroticism, and job characteristics.

Methods

The study was performed by cross-sectional design in 2020 on all operational firefighters from Hamadan, Iran. A total number of 240 firefighters made up the sample size of our study. Data were collected using validated questionnaires during nine months. Hypothesis testing and data analysis were performed using structural equation modeling (by Amos software version 24) and hierarchical regression (by the 23rd version of SPSS software).

Results

PTSS fully mediated the relationship between trauma load and CFs. Trauma load, resilience, and neuroticism were significant predictors of PTSS (p<0.05). Resilience and neuroticism had no moderation effect on the relationship between trauma load and PTSS (p>0.05). PTSS showed a direct relationship with CFs (p<0.001). Among job characteristics, only job control moderated the relationship between PTSS and CFs (p<0.05).

Conclusion

trauma load can increase the rate of CFs by causing PTSS in firefighters. High job control at work can weaken the relationship between PTSS and CFs.

The current research results have differences in the correlation between situation awareness (SA) and physiological data, and there is a lack of systematic research on the influence of motivation and noise on SA. This study investigated the correlation between SA and electroencephalogram (EEG) signals under the effects of motivation and noise.

The independent variables were motivation (two levels: positive and negative) and noise (three levels: no noise, natural noise, and speech noise). And the dependent variable were the levels of SA in perception, comprehension and projection. Participants were required to observe traffic videos of three types of noise under two types of motivation and complete the Situation Awareness Global Assessment Technique (SAGAT) questionnaire after each video. We recorded the participants' EEG signals and calculated the average relative power of the delta, theta, alpha, and beta bands of each brain region.

The results showed that the levels of perception and projection under negative motivation were higher than those under positive motivation. The level of perception was negatively correlated with the delta band power in the central lobe and theta power in the occipital lobe. The level of projection was negatively correlated with the delta band power in the frontal, central, parietal, and occipital lobes, positively correlated with the theta band power, and negatively correlated with the delta band power in the temporal lobe. Therefore, negative motivation can improve the individual's perception and projection levels. The delta and theta band power may reliably measure SA.

This study can help improve team member's SA by establishing motivational rules and better develop physiological measures of SA.

Rehabilitation products for people with cognitive disorders (CDs) have gained increasing attention due to the aging population. However, existing approaches to rehabilitation product design do not adequately consider the importance of feedback information. To address this issue, two VR products with different roaming environments were developed, and 30 elderly participants completed an ergonomic experiment while objective user physiological data were continuously collected using functional near-infrared spectroscopy (fNIRS). The shifts in the subjects’ brain function were analyzed from brain activation and effective connectivity perspectives. Results indicated that VR stimulates various brain areas, with an immersive interactive environment the main influencing factor. There were notable variations in how different virtual settings stimulated individual brain functions. Environmental variables should be included in selecting rehabilitation product design theories. This study provides a quantitative assessment of product ergonomic design for the CDs population and offers guidance in the design of rehabilitation products.

Relevance to industry

This study developed VR rehabilitation products for cognitive disorders based on data-driven product design. Brain function data were introduced to propose a quantitative assessment method for the rehabilitation efficacy of VR products. VR product design is a hot issue in the industry. Evaluating the efficiency of VR products is an urgent challenge for the industry.

Warning stages and takeover strategies are two key factors that affect the takeover process when highly automated systems fail. However, the interaction between these two factors remains unclear. This study empirically investigated the effect of warning types (two-stage warning vs. single-stage warning) and takeover strategies (interruption vs. multitasking) on human performance. Thirty-eight participants performed three tasks of the Multi-Attribute Task Battery (MATB), in which the system monitoring task was automated and adopted as the takeover task, while tracking and resource management tasks were employed as the initial tasks simultaneously. The results showed that compared with the single-stage warning system, the two-stage warning system enhanced situation awareness, reduced mental workload and improved takeover performance. However, tracking task performance declined when the two-stage warning system was used. Moreover, participants using the two-stage warning system reacted to gauge malfunctions much more quickly than participants using the single-stage warning system when the interruption strategy was adopted. However, there was no significant difference in tracking task performance between the two warning systems when the multitasking strategy was adopted. This study concluded that the two-stage warning system can benefit the takeover process but at the cost of the performance of initial tasks, and the takeover strategy plays an important role in realizing the benefits of the two-stage warning system and alleviating its costs. These findings could provide useful insights for automated system design and personnel training.