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Waldemar Karwowski

Publications and source records attributed to Waldemar Karwowski.

14 recordsLinked to original sources

The Work Compatibility Improvement Framework: an integrated perspective of the human-at-work system.

The industrial revolution demonstrated the limitations of a pure mechanistic approach towards work design. Human work is now seen as a complex entity that involves different scientific branches and blurs the line between mental and physical activities. Job design has been a traditional concern of applied psychology, which has provided insight into the interaction between the individual and the work environment. The goal of this paper is to introduce the human-at-work system as a holistic approach to organizational design. It postulates that the well-being of workers and work outcomes are issues that need to be addressed jointly, moving beyond traditional concepts of job satisfaction and work stress. The work compatibility model (WCM) is introduced as an engineering approach that seeks to integrate previous constructs of job and organizational design. The WCM seeks a balance between energy expenditure and replenishment. The implementation of the WCM in industrial settings is described within the context of the Work Compatibility Improvement Framework. A sample review of six models (motivation-hygiene theory; job characteristics theory; person-environment fit; demand-control model; and balance theory) provides the foundation for the interaction between the individual and the work environment. A review of three workload assessment methods (position analysis questionnaire, job task analysis and NASA task load index) gives an example of the foundation for the taxonomy of work environment domains. Previous models have sought to identify a balance state for the human-at-work system. They differentiated between the objective and subjective effects of the environment and the worker. An imbalance between the person and the environment has been proven to increase health risks. The WCM works with a taxonomy of 12 work domains classified in terms of the direct (acting) or indirect (experienced) effect on the worker. In terms of measurement, two quantitative methods are proposed to measure the state of the system. The first method introduced by Abdallah et al. (2004) identifies operating zones. The second method introduced by Salem et al. (2006) identifies the distribution of the work elements on the x/y coordinate plane. While previous efforts have identified some relevant elements of the systems, they failed to provide a holistic, quantitative approach combining organizational and human factors into a common framework. It is postulated that improving the well-being of workers will simultaneously improve organizational outcomes. The WCM moves beyond previous models by providing a hierarchical structure of work domains and a combination of methods to diagnose any organizational setting. The WCM is an attempt to achieve organizational excellence in human resource management, moving beyond job design to an integrated improvement strategy. A joint approach to organizational and job design will not only result in decreased prevalence of health risks, but in enhanced organizational effectiveness as well. The implementation of the WCM, that is, the Work Compatibility Improvement Framework, provides the basis for integrating different elements of the work environment into a single reliable construct. An improvement framework is essential to ensure that the measures of the WCM result in a system that is adaptive and self-regulated.

Employment↗

Nonlinear dynamical behavior of surface electromyographical signals of biceps muscle under two simulated static work postures.

The primary objective of this study was to explore nonlinear characteristics, if any, of the surface myoelectrical (EMG) activity of the biceps muscle during simulated maximum voluntary contraction at a reference arm posture (MVCRP), and at an elevated static arm work posture (EAWP) observed on the manufacturing assembly line. The results showed that positive Lyapunov exponents existed for each of the trials in both work postures. The statistical test of significance showed that surface EMG of the biceps brachii was more chaotic under the MVCRP condition as compared to the EWAP condition. Based on the Kaplan-Yorke dimension, it was observed that the recorded two types of time series EMG data were similar in complexity. The study also found a significant difference in fractal dimensions between the two postures. It was concluded that the nonlinear dynamical EMG properties expressed in terms of the Lyapunov exponents, Kaplan-Yorke dimension, and fractal dimensions could be used as sensitive indices for evaluation of the level of muscular efforts under static work conditions.

Adult↗

Joint angles of isocomfort for female subjects based on the psychophysical scaling of static standing postures.

This study investigated the joint angles of isocomfort (JAIs) for females based on the psychophysical scalings for static standing postures held for 60 s, which were obtained in a laboratory experiment. The subjects were instructed to rate their comfort levels for varyious joint postures by using the free modulus method of magnitude estimation. The comfort scores for the joint postures and the related verbal comfort categories were subjected to regression analysis in order to obtain the JAIs corresponding to verbal categories. The results showed that the JAIs were significantly different depending upon the joints and joint postures investigated (p < 0.01), and that the JAIs for female subjects were significantly different than those for males (p < 0.01) which had been obtained in an earlier study (Kee and Karwowski, 2001). Compared to the corresponding range of joint motion values, the JAIs for hip postures were the smallest of all joint postures dealt with in this study, while those for the neck were the largest of all postures, which means that hip postures are more stressful than any other joint posture. Based on this study, it is recommended that the gender-based JAI values should be used for design applications.

Adult↗

Activity theory as a basis for the study of work.

Activity theory has been successfully applied in diverse schools of psychology with particularly extensive work in the fields of education, ergonomics, human factors and industrial-organizational psychology. However, existing efforts of translation and formulation in English suffer from certain limitations. These limitations include the blurring between Vygotsky's socio-cultural theory of the development of mind and activity theory, the restriction of activity theory in its entirety to the version offered by Leont'ev, errors in the interpretation of some basic concept and terminology, reliance on studies that use obsolete methods, and failure to consider the Russian work in activity theory in its entirety. This last problem results in the omission of the recent advances in engineering psychology and educational psychology in the former Soviet Union that facilitates the application of activity theory to practical problems. This paper is a description of the evolution of basic theory, concepts and terminology relevant to practitioners--particularly in the field of ergonomics.

Ergonomics↗

An assessment system for rating scientific journals in the field of ergonomics and human factors.

A method for selecting and rating scientific and professional journals representing the discipline of ergonomics and human factors is proposed. The method is based upon the journal list, impact factors and citations provided by the Institute of Scientific Information (ISI), and the journal list published in the Ergonomics Abstracts. Three groups of journals were distinguished. The 'ergonomics journals' focus exclusively on ergonomics and human factors. The 'related journals' focus on other disciplines than ergonomics and human factors, but regularly publish ergonomics/human factors papers. The 'basic journals' focus on other technical, medical or social sciences than ergonomics, but are important for the development of ergonomics/human factors. Journal quality was rated using a maximum of four categories: top quality (A-level), high quality (B-level), good quality (C-level)) and professional (P-level). The above methods were applied to develop the Ergonomics Journal List 2004. A total of 25 'ergonomics journals', 58 'related journals' and 142 'basic journals' were classified.

Ergonomics↗

A neuro-fuzzy model for estimating electromyographical activity of trunk muscles due to manual lifting.

The main objective of this study was to develop a hybrid neuro-fuzzy system for estimating the magnitude of EMG responses of 10 trunk muscles based on two lifting task variables (trunk velocity and trunk moment) as model inputs. The input and output variables were represented using the fuzzy membership functions. The initial fuzzy rules were generated by the neural network using true EMG data. Two different laboratory-derived EMG data sets were used for model development and validation, respectively. The mean absolute error (MAE) between the actual and model-estimated normalized EMG values was calculated. Across all muscles, the average value of MAE was 8.43% (SD=2.87%) of the normalized EMG data. The larger absolute errors occurred in the left side of the trunk, which exhibited higher levels of muscular activity. Overall, the developed model was capable of estimating the normalized EMG values with average value of the mean absolute differences of 6.4%. It was hypothesized that model performance could be improved by increasing the number of inputs, including additional task variables as well as the subjects' characteristics.

Biomechanical Phenomena↗

Ecological models of human performance based on affordance, emotion and intuition.

This paper proposes a complementary approach to Rasmussen's taxonomy of the human skill-, rule-, and knowledge-based performance models by combining the ecological concept of affordances with the neural concepts of human emotion and intuition. The classical cognitive engineering framework is extended through the neuro-ecological approach, including personal human attributes important in exercising control over the work environment. The proposed affordance-, emotion-, and intuition-based models correspond to the three types of human performance, namely: learning, adaptive and tuning control, respectively. The new framework is not a predictive model of the operator behaviour, but rather it describes the processes of neuro-ecological control of the human environment.

Cognition↗

Ranking systems for evaluation of joint and joint motion stressfulness based on perceived discomforts.

This study aims to develop ranking systems for evaluation of the stressfulness of joints and joint motions based on perceived discomforts measured through an experiment. Twenty healthy male subjects participated in the experiment, where discomforts for varying joint motions in the sitting and standing postures were measured using the magnitude estimation. The results showed that the perceived discomforts were affected by the type of joint motions, size of joint motions, and joints. The joints and joint motions were classified into several distinct classes according to perceived stresses. Three ranking systems based on the perceived discomforts were developed, including classification by the joint motions and joints, by types of joint motions, and by the joints only. The ranking systems revealed that while hip and back motions exhibited higher discomfort ratings than any other joint motion, elbow motions were the least stressful of all joint motions. The ranking systems can be used as a valuable design guideline when ergonomically designing or evaluating workplaces, or as a helpful tool for understanding adverse effects of poor working postures.

Adult↗

A study of computer-based task performance under thermal stress.

A visual-visual dual computer task was designed to test the effect of the thermal environment on dual task performance. The temperatures selected for testing were 20 and 35 degrees C Wet Bulb Globe Temperature (WBGT). 34 volunteers were randomly assigned to 1 of the 2 temperature conditions. Individual differences in single task performance were controlled by equating the baselines of single task performance. Once individual differences in single task capacity were controlled, statistically significant differences in performance were demonstrated. Mean accuracy was computed over a 1-hr testing period in each temperature condition. Participants' mean accuracy in the 35 degrees condition (38.18%) was substantially lower than in the 20 degrees condition (50.88%).

Adult↗

Assessing the compatibility of work system factors through an integrative model: a case study.

Work Factor Compatibility (WFC) theory proposes that human performance is dependent on the interaction of various components (e.g., physical and mental task demands, physical environment, social environment) of the work system and integrates multiple human performance perspectives into a single mathematical model. Work Factor Analysis (WFA) is a comprehensive survey administered to employees to determine the WFC index. WFA also provides recommendations for targeting specific work system areas for improvement. Preliminary testing of the tool was conducted at a manufacturing operation of a Fortune 10 company. Results are discussed and recommendations for further study are made.

Efficiency↗

Reliability and validity of self-reported assessment of exposure and outcome variables for manual lifting tasks: a preliminary investigation.

The reliability and validity of self-reported assessment of exposure and outcome variables were examined for manual lifting activities among ten physiotherapists. In this study, the participants evaluated the effects of five lifting variables on perceived effort, twice separated by a one-week period. One hundred and sixty-two lifting conditions were evaluated by each subject. The exposure and outcome lifting variables were described in linguistic terms. Intra-class correlation coefficient (ICC(1,1)) analysis revealed a mean value of 0.62 for all lifting activities. The self-reported assessment was cross-validated with the NIOSH lifting index by mapping the linguistic variables into numerical ranges. Moderate correlations (r = 0.54 and 0.53, p<0.01) were obtained between perceived physical exertion/perceived risk and lifting index. The findings of this study provide preliminary indications that human-based methodologies may be further explored on experienced workers.

Adult↗

The relationships between biomechanical and postural stresses, musculoskeletal injury rates, and perceived body discomfort experienced by industrial workers: a field study.

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.

Adult↗

Evaluation of different scales for measurement of perceived physical strain during performance of manual tasks.

The main objective of this study was to evaluate different scales of perceived strain during the performance of various physical tasks. A total of 52 male and female participants took part in 4 experiments to achieve the study objective. The results suggest that a bipolar comfort-discomfort scale is a more appropriate instrument than a discomfort scale for assessing cumulative physical stresses at work, especially at the beginning of the shift. For assessing discomfort at the end of the work shift, a unipolar scale may also be used. On the basis of the obtained results, red, green, and yellow zones are suggested to establish priorities for work redesign efforts in ergonomic control programs.

Adult↗

Analytically derived three-dimensional reach volumes based on multijoint movements.

The main objectives of this study were to quantify the range of reaching for the upper body with eight degrees of freedom (the trunk and shoulder, elbow, and wrist joints) and the lower body with six degrees of freedom (the hip, knee, and ankle joints). A sweeping algorithm that included trunk and foot motions was used to generate the analytical total reach volume of the human body for young men. Three types of reach volume--unconstrained arm reach, shoulder-restricted arm reach, and foot reach--were generated depending on the joint involved in reach activities. The robot kinematics methodology was employed to represent the human body as a multilink system, which was needed for calculating three-dimensional coordinates of the involved joints. The statistical test results showed that the total reach volume analytically generated in this study was nearly identical to that obtained from the direct human body measurements. Applications of this research include generating the human body's reach volume for the purpose of designing work spaces and products.

Adult↗