Issues : JET is a peer-reviewed, open-access scientific journal : Journal of Ergonomic Technology (JET)

Journal of Ergonomic Technology (JET)
ISSN 2432-1575


Study for reducing stress by adjusting seat height (Part 2) – measuring electromyogram and evaluating posture during VDT work –
Publish Date : 2006/02/01  Vol.6
Authors : 
Chyi-Shium WU, Nan-Hean Junior Institute of Technology,
Hideki OYAMA, Reiko MITSUYA, Kageyu NORO, Waseda University
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 6, No. 1, 1/6, 2003.

The purpose of this study is to investigate the effect of seat height adjustment on VDT work. In order to examine the validity of a sitting height considered proper, VDT tasks were performed while seated at different heights and muscle fatigue was calculated with a power spectrum waveform. Five male university students were used as test subjects. Selected six muscles (anterior deltoid., middle deltoid m., latissimus dorsi m., trapezius m., brachioradialis m. and erector spinae m.) were measured by surface electromyography (EMG). Additionally, tilt of chest and pelvis were measured, to include information about the movement of the subject. Measurements were made for each subject while working at the proper sitting height and at a different height. Data was successfully obtained that indicated the most proper seat height for the physical configuration of each subject in order to minimize muscular fatigue. A significant relationship was found between seat height and muscle fatigue of te deltoid and brachioradialis muscles. The goniographical relationship between seat height and pelvic motion was found to be similarly significant. It is concluded that correctly choosing the seat height for an individual should have a significant effect reducing muscular loads and stress.
Count : 121
Interaction with dual operations under the different stimuli
Publish Date : 2005/02/01  Vol.5
Authors : 
Noriyoshi MATSUO, Suzuki Motor Corporation
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 5, No. 1, 19/22, 2002.

In this paper, mutual influence between dual operations on each stimulus was examined with the cognitive-reaction time (C-RT). Steering in response to the visual stimulus was defined as the main-operation, and its C-RT was named the C-RTmain. In the same way, pushing the switch in response to the auditory stimulus was defined as the sub-operation, and its C-RT was named the C-RTsub. The order and the time lag of the dual stimuli were varied, and each C-RT of the operation was measured. The results showed the following. (1) The difference in the C-RTsub was 0.2 s in the eye’s confirmation of the switch position for the sub-operation or not, and the confirmation did not influence the main-operation. (2) The order of the main-operation and thesub-operation depended on the time lag between the visual stimulus and the auditory stimulus, and there were two way both the serial operation and the parallel operation. (3) In the case of the time lag during both of the stimuli sufficiently, both operations were executed as the way of the serial sub-operation influenced the C-RTmain, at the case of the small time lag, both operation became the way of the parallel operation and the C-RTmain was equal to it of the independent operation.

Keywords: Dual operations, Cognitive-reaction time (C-RT), Visual stimulus, Auditory stimulus
Count : 127
Time series analysis of the body pressure distribution on a long-term seating posture
Publish Date : 2005/02/01  Vol.5
Authors : 
Reiko MITSUYA, Goroh FUJIMAKI, Waseda University
Yoshiyasu TAMURA, The Institute of Statistical Mathematics
Kageyu NORO, Waseda University
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 5, No. 1, 11/17, 2002.

The purpose of this study is to attain the new method for the body pressure distribution analysis on a long term seating. It has been difficult to analyze the pattern of the body pressure distribution. Especially in case of a long term seating it is much tougher. In the view of the above we proposed the new method that is the time series analysis. The subjects were two healthy university students. They were requested to seat cinema chair from 1.5 to 2 hours. With this experiment we could obtain a formula which enabled to predict the discomfort on a long term seating posture. We also found the pressure rhythm through the experiment. Further study of the pressure rhythm is required.

Keywords: Time series analysis, Autoregressive model, Spectrum, Parcor
Count : 154
Subjective evaluation of similarity of figures in questionnaires by different media
Publish Date : 2005/02/01  Vol.5
Authors : 
Taiki KANDA, Bunri University of Hospitality
Hideyo NAGASHIMA, Kogakuin University of Hospitality
Takashi OKUNUKI, Tokyo Shoseki Insatsu
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 5, No. 1, 1/9, 2, 2002.

When similar trademarks are retrieved using computer physical features are extracted from images of trademarks and similarity between trademarks is evaluated based upon the extracted physical features. The results of retrieval, however, do not always coincide with human visual cognitive sense of similarity. Therefore, in order to retrieve similar trademarks reflecting human visual mentality methods have been studying to incorporate human visual subjective evaluation into a retrieval system. For these methods it is important to obtain effective data on human visual evaluation of similarity beween trademarks. To do this we have been utilizing questionnaire. Here a questionnaire system by computer is proposed to extract human visual evaluation of similarity between trademarks, comparison between written and computerized questionnaires is made, and equivalence of questionnaires by different media is studied.

Keywords: Similarity of trademarks, Human visual evaluation of similarity, Computerized questionnaires, Equivalence of questionnaires by different media
Count : 112
Study for reducing stress by adjusting seat height – measuring pelvis inclination angle and evaluating posture during VDT work –
Publish Date : 2004/04/01  Vol.4
Authors : 
Chyi-Shium WU, Kageyu NORO, School of Human Science Waseda University
Hiyoyuki MIYAMOTO, Chiba Institute of Technology
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 4, No.1, 31/38, 1999.

Meanwhile, 95%ile of Japanese adult males are 181.9 cm and 5%ile of Japanese adult females are 151.1 cm and it is difficult for people who are outside of these average height ranges to maintain work posture that does not cause much stress. The purpose of this study, therefore, is to investigate how much of such work related stress can be alleviated by properly adjusting the seat height of a chair. Inclination angles of the chest and pelvis of the subjects ere measured during actual VDT work and their changes were recorded to study the physical movement of the subjects.
As a result, it was found that adjusting the seat height according to an individual’s physical dimensions alone has a limit to alleviating physical stress. Therefore, in order to alleviate physical stress, it is necessary to reconsider VDT work environment b adjusting not only the seat height but also the angle of back rest and the desk height.

Keywords: Chair, Pelvis, VDT work, Seat height, Inclination angle
Count : 144
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