Iranian Journal of Ergonomics

The survey of relationship between bus drivers’ situation awareness, driving performance and cognitive abilities using driving simulator

Seyyed Abolfazl Zakerian

Introduction: One of the most important subjects in the analysis of driver’s behavior had been situation awareness during the past decade. However, no study has been investigated the relation among component of situation awareness and performance and cognitive abilities of bus drivers. Current study aimed to survey relationship between bus drivers’ situation awareness, driving performance and cognitive abilities using driving simulator.

Material and Methods: In this study, 30 professional bus drivers who have diploma or higher degree participated. Situation awareness measured by SAGAT technique and tests UFOV, EFT and WMS were used for measuring of cognitive abilities. Brake reaction time and lane departures were criteria for driving performance.

Results: Accordingly, the result showed significant relation between drivers’ situation awareness before and after hazard conditions. Among WMS, divided attention, selective attention and EFT with level 1 of situation awareness was seen significant relation. The result of current study released a significant correlation among WMS and divided attention with lane departure.

Conclusion: Results showed, in general, the driver's situational awareness in dangerous conditions increases. The study showed that cognitive ability affects only level 1 of situational awareness. According to role of situational awareness in driving performance, the results of lane keeping showed that perception might be a key factor in driving performance.

Cognitive characteristics of the operator of urban traffic control center and framework of Cognitive Work Analysis (CWA)

Sara Dehnavi

Introduction: As the traffic is one of the most common social troubles in big cities, widen the roads culture and using the intelligent methods are using to control the traffic. Therefore, the traffic control systems are innovated. These system operators have to do many cognitive jobs to manage these systems. CWA as a framework to improve the design of these systems has introduced in this paper to analyze them.

Material and Methods: CTA recognizes the restrictions of system throughout the 5 phases that begin with work domain analysis and ends in necessary personal qualification. Task analysis, strategy analysis and investigating the cooperation and organizations are between paces, respect.

Results: the results of this investigation consist of outline of the technique CWA, work domain analysis, decision ladders, details of relevant indicators, strategies, Information Flow Map (IFM), to frame the social organization and cooperation, and worker qualification analysis.

Conclusion: The results of this study may used in selection and training the mentioned systems operators. The main reason is to use the experienced staff with high cognitive abilities in working with these systems. Otherwise, it can result in waste the organization money and energy. The operator decision making is more dependent on the information process, the operator also needs to have higher cognitive abilities. Strong visual search, timing and problem solving are perquisites of this job opportunity.

Predictive factors of neck pain in dentists

Mahnaz Saremi

Introduction: High prevalence of neck pain has become an important health complain among dental practitioners which is followed by reduced working performance, burnout and early retirement. The purpose of this study is to assess the relationship between individual and occupational risk factors as well as forward head posture (FHP) with dentist’s neck pain and to determine the priority of these factors in the development of the neck pain.

Material and Methods: In this cross - sectional study, 70 dentists of two dental centers in Tehran were examined with clinical testing of FHP. Individual and job characteristics were collected by means of a questionnaire. The visual analog scale (VAS) was applied in order to determine the severity of pain in various parts of the body. Spearman and Pearson correlation coefficient and multiple linear regressions were used to examine the relationship and effect of the studied variables in creating the neck pain.

Results: According to the results, neck was the most painful part of the body (66.6%). Indeed, 40 (57.1%) of participating dentists were suffering from the forward head posture. The results of the multiple linear regression showed that the FHP with the standard coefficient (β= 0.64) was the most influential factor in predicting the incidence of neck pain.

Conclusion: The FHP has a greater impact than any other individual and job factors in creating neck pain. It may be concluded that awkward neck posture is the most important risk factor for neck pain in static sitting jobs such as dentistry.

Ergonomic workplace evaluation in production clinics of artificial limbs and assistive devices

Hadi Daneshmandi

Introduction: In the orthotic and prosthetic workshops, awkward postures, repetitive and continuously movements etc. are the risk factors of musculoskeletal disorders (MSDs). This study was conducted with the objective of ergonomic assessment of working conditions in these workshops.

Material and Methods: In this study all employed personnel of linorthotic and prosthetic production centers in Shiraz city participated (n=42).Data were collected using Nordic Musculoskeletal disorders Questionnaire (NMQ) and Ergonomic Risk Factor checklist (ERF)for assessment of working conditions .Data analysis was performed using SPSS software (Ver. 16).

Results: The means (SD) of age and job tenure (years) in employees studied were 37.26 (10.21) and 12.8 (9.39), respectively .The most prevalent MSDs symptoms were reported in lower back (42.9%), shoulder (40.5%) and knee (40.5%).Working condition assessment by ERF check list revealed that the means core of upper and lower region of body and also mean of total score were higher than acceptable limit (more than 7)..

Conclusion: In working conditions improvement, corrective measures and MSDs risk factors control in studied workers should be noted to risk factors in low back, shoulder and knee. The results of this study showed that ergonomic problems in orthotics and prosthetics clinics was related to "custom shoe making", "grinding and finishing", "filling plaster cast" and "positive cast rectification" tasks and ergonomic interventions to decrees and/or eliminate of awkward working posture needed corrections.

An ergonomic assessment of musculoskeletal disorders risk among the computer users by RULA technique and effects of an eight-week corrective exercises program on reduction of musculoskeletal pain

Rashid Heydari Moghadam

Introduction: The prevalence of work-related musculoskeletal disorders in computer users is high. The purpose of this study was to evaluate ergonomic assessment musculoskeletal disorders risk in computer users determine the effect of an eight-week corrective exercises program on reduction of musculoskeletal pain.

Material and Methods: In the first phase of the study, RULA technique and Nordic questionnaires were used to evaluate postures and musculoskeletal disorders of 84 computer users of Tuyserkan administrations. In the next phase, 30 individuals for participating in a corrective exercises program intervention divided into two groups namely, experimental (n=15) and the controls (n=15). Subjects were re-evaluated after period of eight weeks. Data was analyzed using independent and dependent t-tests.

Results: The overall prevalence of pain was seen in neck, lumbar, shoulders, back, carpal and hand, elbow respectively. In posture analysis, 61.3 and 53.6 percent of subjects were in action level of 2 in left and right limbs respectively, 32.2 and 44.1 percent of subjects were in action level of 3 and 2.4 percent in level of 4 in right side. After the corrective exercise intervention, there was 38.3% significantly reduction pain for upper limbs (p=0.001) and 38.7% for lower limbs (p=0.006).

Conclusion: This study showed that frequency of musculoskeletal problems in neck, lumbar, shoulders, back, wrist was generally high among our subjects, and selected corrective exercises could reduce the risk level and pain.

The validity and reliability of an usability assessment tool for a web-based software

Javad Keshvari Kamran

Introduction: Index of usability evaluates performance, user satisfaction and increased productivity in a product. Principles of usability are effectiveness, efficiency, safety, utility, learnability, Memorability. This Study Aims to Develop a Tool to Estimate and Evaluate the Usability of Web Applications in the field of Automation Research has been determined.

Material and Methods: After extracting, an initial questionnaire to assess the usability of the standard resource for indices of validity, internal consistency and reproducibility, respectively technique for determining the content validity, test-retest method and cronbach's alpha coefficient were used. The most important steps were as follow: (1) determine the scope and dimensions of the questions (2) preparing draft questionnaire (3) appoint the members of the expert panel (4) methods, how data analysis (5) determine the acceptance criteria of the questions (6) determine the content validity index (7) determine reliability of the questionnaire (8) determine reproducibility of the questionnaire.

Results: A 50-Item questionnaire was designed as the ultimate tool. The content validity index value of 0.763 was obtained ultimately for the questionnaire. Analysis of the questionnaire responses revealed that the lower backend errors related to the reliability coefficient alpha value was equal to 0.742. Finally, the degree of reproducibility of the questionnaire, using test-retest method, was equal to value of 0.993 (p <0.001).

Conclusion: After the final questionnaire design, with good reliability and validity, it is noticeable that the designed tool is applicable on relevant softwares and may improve the quality and efficiency of the software and user interface.

Using the human information-processing model and workload to predict staffing demand: A case study in a petrochemical control room

Afshin Dibeh Khosravi

Introduction: In many sensitive and sophisticated workplaces, human errors are very important. Many events occur annually around the world is evidence to confirm error due to the data processing operators. The main goal of this study was to investigate human information processing models and workload demands on human operators, then developing a regression model for this purpose.

Material and Methods: This was a case study. Task analysis of control room members, including shift supervisor, board man, and site man and user instrumentation in this study was investigated. Data collection was performed by interviewing employees using a questionnaire with two parts the first part was the model of human information processing and the second part was workload NASA–TLX and an appendix of opinions existing staffing level and finally task analysis performed using SPSS 16 – SPSS.

Results: There was a correlation between workload and stages of human information processing model such as perception )r=0.65, p<0.01), vocal response (r=0.45, p<0.01) and manual response (r=0.15, p<0.05). Some effective factors on workload were vocal response (β=0.232, p=0.033) and perception (β=0.576, p=0.00). The most important factors in the analysis of anticipation staffing demand were perception (β=2.514, p=0.008), workload (β=1.57, p=0.018) and vocal responses (β=2.428, p=0.01), respectively.

Discussion and Conclusion: Increasing concentration and attention and perception skills using psychological measures including decreasing the workload and stress and holding specialized training courses are necessary.

Assessing the appropriateness of educational furniture with body size of students in Yazd

Habib Noori

Introduction: Due to the deleterious effects of mismatch between body dimensions of students and educational furniture, this study aimed to assess the size of students’ body in Yazd.

Material and Methods: The study population included all high school students in Yazd city. Popliteal height, buttock-popliteal length, elbow rest height, hips width, thighs thickness and scapular elevation were measured in 307 students. Besides, in furniture used in the schools studied, two chairs and two benches that had a greater frequency of analysis were chosen.

Results: The results of the statistical comparisons showed that type 1 furniture, seat width was acceptable for 96.74% and thigh freedom was 100% fit. The type 2 furniture depth for most students was appropriate, and seat width was acceptable for 96.42% of students. Thigh freedom was fit for 100% with a good rating. In type 3 furniture, there was not any parameter with good fit and in type 4 furniture, wide seat width and thigh freedom was desirable.

Conclusions: In general, the furniture conformity with students’ anthropometry was not desirable.