Industrial Health
Online ISSN : 1880-8026
Print ISSN : 0019-8366
ISSN-L : 0019-8366
Volume 6 , Issue 4
Showing 1-5 articles out of 5 articles from the selected issue
  • Toshisuke MIWA
    1968 Volume 6 Issue 4 Pages 143-164
    Published: 1968
    Released: April 17, 2008
    JOURNALS FREE ACCESS
    Perceptional and emotional responses on continuous sinusoidal vibrations characteriz-ed as vibration greatness and unpleasant or unbearable feeling were reported in the pre-vious papers.
    In this paper, the vibration greatness of three kinds of pulses such as pulsed sinusoidal, damped and built-up vibrations is obtained in comparison with a continuous sinusoidal vibration. The frequency of the continuous sinusoidal vibration is selected to be the same as the fundamental frequency of each pulse. Ten male subjects sitting erect are given the whole body vibration in vertical and horizontal directions and the hand vibration in vertical direction.
    Durations and fundamental frequencies of the pulsed sinusoidal vibrations are changed between 0.005 and 6 sec, and 2-300 Hz respectively, but their level is maintained constant. The vibration greatness of the pulsed sine waves increases with their dura-tion up to approximately 2 sec in the frequecy range between 2 and 60 Hz. The rate of the increase can be approximated by the straight line with the slope of 7 dB / decade of duration.
    The vibration greatness of the damped vibration can be evaluated by peak-to-peak amplitude and duration of initial one period of its fundamental frequency.
    The vibration greatness of the built-up vibration can be estimated by its maximum peak-to-peak amplitude, fundamental frequency and duration corresponding to the am-plitude 1.5 dB below the maximum peak-to-peak amplitude.
    The perceptional threshold for the pulsed sinusoidal waves is also measured and can be approximated by the line with the same slope as that of the vibration greatness (7 dB / decade of duration).
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  • Hisato HAYASHI
    1968 Volume 6 Issue 4 Pages 165-220
    Published: 1968
    Released: April 17, 2008
    JOURNALS FREE ACCESS
    About 55 dead cases due to oxygen deficiency have been reported in underground construction works in Japan from 1960 to 1968. In Tokyo area, where dead cases amount to 20, these accidents mostly occurred in pneumatic caisson arriving at subsurface Pleistocene gravels. The cause of oxygen deficiency was studied geologically, mineral-ogically, and geochemically.
    Accidents have occurred in gravel layers in central part and in sand layer in southern part of Tokyo. The former belongs to lower gravel layer of the Upper Tokyo Forma-tion and distributes around 20 m under ground surface, while the latter belongs to the Upper Tokyo Formation and extends about 10 m below the surface. These gravel and sand layers are covered with impermeable silt or clayey sediments. Water table and pore-water pressure in these layers have decreased remarkably by excessive pumping for industrial use year by year. The excavation for construction has to arrive at the gravel layer since the gravel layer is selected as the strata on which the basements of all constructions are established. Under these conditions, the compressed air for pneumatic foundation can pass easily through these gravel layers, and oxygen in it is consumed to oxidize the ferrous ion in pore water to ferric ion. Although ferrous ion content of pore water in gravel layers is small in the absolute value, total volume of iron in them is remarkably large as compared with the volume of the compress-ed air sent artificially, because gravel layers distribute widely in the ground.
    Accidents of this type have happened, or will possibly happen, in other Japanese populous cities along the coastal area, because they have similar geological environ-ments and are suffering from lowering of underound water table.
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  • Yoshimi MATSUMURA, Akira HAMADA
    1968 Volume 6 Issue 4 Pages 221-224
    Published: 1968
    Released: April 17, 2008
    JOURNALS FREE ACCESS
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  • 1968 Volume 6 Issue 4 Pages 225b
    Published: 1968
    Released: April 17, 2008
    JOURNALS FREE ACCESS
    Download PDF (62K)
  • 1968 Volume 6 Issue 4 Pages 225a
    Published: 1968
    Released: April 17, 2008
    JOURNALS FREE ACCESS
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