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

Journal of Ergonomic Technology (JET)
ISSN 2432-1575

Issues

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 : 144
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 : 105
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 : 126
A proposal for frequency analysis method of unevenly spaced time series data
Publish Date : 2004/04/01  Vol.4
Authors : 
Tu YUXIN, Shigeyuki KON, Satoshi HONDA, Department of Instrumentation Engineering, Faculty of Science and Technology, Keio University
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 4, No.1, 27/30, 1999.

A novel method for unevenly spaced time series is proposed. Since Fast Fourier Transform (FFT) method cannot Fourier transform unevenly space time series, such as heart rate, respiratory rate, etc., we have had to precondition the data for frequency analysis. With the present method a direct discrete Fourier transform is performed. We compared the conventional FFT and the present methods numerically, and found that the conventional method showed lower power spectrum in high frequency region, whereas the present one showed the correct power spectrum. As an example, heart rate variability was investigated in frequency domain, and the results were compared with those of conventional methods, and found that in respiratory frequency range (0.2-0.4 Hz), the present method gave better spectrum estimate.

Keywords: Frequency analysis, Unevenly sampled time series, Heart rate variability, Stress
Count : 108
Center of gravity measuring system for nursing
Publish Date : 2004/04/01  Vol.4
Authors : 
Nobuaki AGETSUMA, Koichi OGAWA, Tokyo Denki Universit
Report Outline : 
Original article
Appeared on Ergonomics of Human System Interaction, Vol. 4, No.1, 21/26, 1999.

This study aims to develop a new measuring system for the analysis of nursing motion. The system obtains reaction forces, the center of gravity, its locus, and the foot positions to measure nursing motions, such as transferring a patient from a bed to a wheel chair, or assisting a patient from lying positon to sitting position. Instead of using a large force plate, we used a pair of shoe-size force plates, which we call ‘force-shoe’, tow displacement sensors, four potentiometers, a dynamic strain meter, and the error is five millimeters.

Keywords: Center of gravity, Ground reaction force, Nursing posture, Area of base
Count : 108
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