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

Journal of Ergonomic Technology (JET)
ISSN 2432-1575

Issues

Development of new ergonomic-mat with pelvic support (Ergo-Zabuton)
Publish Date : 2005/02/01  Vol.5
Authors : 
Hideki OYAMA, Taku TERAOKA, Kageyu NORO, Waseda University
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 5, No. 1, 11/18, 2002.

This paper presents a new ergonomic mat ‘Ergo-Zabuton’ with the pelvic support. It was developed in order to prevent the musculoskeltal disorders (MSDs) for floor seating. The feature of seating tool is following. In order to reduce the rear rotation of the pelvis, the pelvic support was put into use. The material is hard chipped cork. Cushion material is the polyurethane wrapped with soft polyester. There are differences between male and female in the Japanese floor-seated postures, therefore two models were developed. Its effectiveness was examined through the measuring of pelvic motion and subjective evaluation. The experiment demonstrated the advantages of ‘Ergo-Zabuton’ as being reduced rea rotation of pelvis, a posture that can be maintained over time and reduced fatigue of the upper body. The mat with pelvic support is proposed, as one of useful tool for the floor seating.

Keywords: Floor seating, Musculoskeltal disorders (MSDs), Pelvic support, Pelvis
Count : 147
Calculation of a 3-dimensional sensitivity distribution of single difference, double difference, and concentric-ring systems
Publish Date : 2005/02/01  Vol.5
Authors : 
Hiroharu ENDOH, Junichi USHIBA, Yoshihiro MURAOKA, Keio University
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 5, No. 1, 7/10, 2002

The sensitivity distribution of single differential (SD), double differential (DD) and concentric-ring (CR) systems were computed in a homogeneous, anisotropic semi-infinite volume conductor model. The results of the calculation showed that the DD and CR systems had higher spatial selectivity than that of the SD system.

Keywords: Sensitivity distribution, Double differential, Concentric-ring system, Volume conductor, Anisotropy
Count : 154
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 : 136
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 : 145
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 : 170
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