Min-Yong Park

Ergonomic design and evaluation of a new VDT workstation chair with keyboard–mouse support

Abstract A new-concept VDT workstation chair with an adjustable keyboard/mouse support was proposed to minimize the physical discomfort and the risk of cumulative trauma disorders (CTDs) at work sites. A three-dimensional human modeling tool (SAFEWORK ® ) was used to design the new chair which satisfies the anthropometric specifications of the Korean population. Based upon the result of 3-D graphical simulations, a mock-up chair was constructed with an adjustable keyboard/mouse support directly attached to the chair body. An experiment was conducted to compare the new workstation chair to a conventional computer chair without a keyboard–mouse support by measuring muscle fatigue and subjective discomfort. Six volunteer subjects participated in six 1-hour word-processing sessions with two different chairs and three different work postures. Statistical results indicated that the new-concept VDT chair generally improved subjective comfort level and reduced fatigue in the finger flexor/extensor and the low back muscles. Implications of the new design and suggestions for further development are addressed. Relevance to industry The proposed VDT chair in this study can be used by certain VDT users such as telephone operators who are potentially exposed to CTDs. Since the number of computer users has greatly increased, the market share of better-designed VDT chairs is expected to increase rapidly. Moreover, the new VDT chair can impact design and manufacturing industries that make new products and accessories which support the new VDT environment.

Multidimensional quality assessment of multimedia telecommunications systems for enhancing customer satisfaction

The primary objective of this research is to establish and quantify the relationship between the quality factors of multimedia telecommunications systems and subjective human perception of the system quality. Three quality factors (explanatory variables) were considered: degree of voice delay (time-lag between audio and video), frame rate per second, and display resolution. For assessing the human sensibilities of the system, a number of adjectives were selected and abstracted to eight representative syllables (response variables) using semantic differential (SD) scales and factor analysis. Simulators were developed in two sound-treated chambers equipped with audio/video equipment running under a custom-developed software program. Experiments showed that the voice delay and frame rate have a significant impact on the subjective perception of the system quality. An aggregated sensibility index was also established to verify the adequacy of the selected response variables. A linear regression model with indicator variables showed that the index agrees well with the users’ overall satisfaction for each experimental condition. The results provide some fundamental data on the human subjective perception of multimedia telecommunications quality, and further can help establish the quality standards to enhance customer satisfaction.

Ergonomic interventions for prevention of work-related musculoskeletal disorders in a small manufacturing assembly line

This study involves performing improvements in workstation specification using a three-dimensional human modeling tool and proposing well-balanced work scheduling (WBWS) to prevent work-related musculoskeletal disorders (WMSDs) in a small manufacturing plant. To analyze risk factors of WMSDs, various tasks at 10 different types of workstation were evaluated with detailed motion analysis using a customized checklist. Questionnaires were administered to 27 workers to evaluate symptoms related to WMSDs. Revised workstation specifications were suggested based on anthropometric characteristics of workers using before–after analyses as an engineering control. Additionally, WBWS was proposed as an administrative control to avoid continuous physical stress on specific body parts in repetitive tasks. A software tool for WBWS was developed for convenient and easy application. The results of the study may aid managers in applying ergonomic interventions with time and cost savings, and enhance worker satisfaction and motivation due to improvements in working conditions to prevent WMSDs.

Quantitative Analysis Of User Interfaces For Large Electronic Home Appliances And Mobile Devices Based On Lifestyle Categorization Of Older Users

ABSTRACT Background/Study Context: The increasing longevity and health of older users as well as aging populations has created the need to develop senior-oriented product interfaces. This study aims to find user interface (UI) priorities according to older user groups based on their lifestyle and develop quality of UI (QUI) models for large electronic home appliances and mobile products. Methods: A segmentation table designed to show how older users can be categorized was created through a review of the literature to survey 252 subjects with a questionnaire. Factor analysis was performed to extract six preliminary lifestyle factors, which were then used for subsequent cluster analysis. The analysis resulted in four groups. Cross-analysis was carried out to investigate which characteristics were included in the groups. Analysis of variance was then applied to investigate the differences in the UI priorities among the user groups for various electronic devices. Finally, QUI models were developed and applied to those electronic devices. Results: Differences in UI priorities were found according to the four lifestyles (“money-oriented,” “innovation-oriented,” “stability- and simplicity-oriented,” and “innovation- and intellectual-oriented”). Twelve QUI models were developed for four different lifestyle groups associated with different products. Three washers and three smartphones were used as an example for testing the QUI models. Conclusion: The UI differences of the older user groups by the segmentation in this study using several key (i.e., demographic, socioeconomic, and physical-cognitive) variables are distinct from earlier studies made by a single variable. The differences in responses clearly indicate the benefits of integrating various factors of older users, rather than single variable, in order to design and develop more innovative and better consumer products in the future. The results of this study showed that older users with a potentially high buying power in the future are likely to have higher satisfaction when selecting products customized for their lifestyle. Designers could also use the results of UI evaluation for older users based on their lifestyle before developing products through QUI modeling. This approach would save time and costs.