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Volume 33, Issue 6
Displaying 1-7 of 7 articles from this issue
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Maki KATO, Hajime TAKEOKA, Toshiro ISHIDA1997 Volume 33 Issue 6 Pages 343-347
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn this study, changes of the pressure distribution of a chair used at work was measured with a pressure measurement system. The pressure distribution was divided into three sections: the large thigh, the buttock, and the dorsal section, and each section was changed into a power-spectrum of a time series. We compared the inclination of the recurrence of the straight line of the power spectrum and the frequency with ‘1/f Swinging’ which shows the degree of comfortableness. The subjects are 8 university students. They performed word-processing input work for 45 minutes, after which, they subjectively evaluated the chair. We measured the pressure distribution at every second. The results were as follows: The pressure distribution showed a changed random time series pattern. Therefore, a static evaluation index is unreliable; and the recurrence analysis was done between the each power spectrum and the frequency. We compared the regression line with ‘1/f Swinging’. Concerning the large thigh and the buttock, the correlation coefficient between the subjective evaluation and the variable coefficient of the regression line was low. However, we obtained an extremely high correlation between the regression line and the subjective evaluation for the dorsal section.View full abstractDownload PDF (4888K) -
Hiroaki SUZUKI1997 Volume 33 Issue 6 Pages 349-355
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn order to identify the effective vibrational factors which determine the riding comfort of railway vehicle, an experiment was performed in running train. Twenty two male subjects participate in this experiment. The task of the subjects is to rate the riding comfort in 4-rank basis in a series of blocks each 5 seconds long. Vibrational acceleration and stationary acceleration are recorded as physical indices. According to the result, the correlation coefficients between rating average and some indices of the above mentioned vibrational factors are about 0.75-0.80. Considering the well-known anchoring effect that vibrational perception depends, not only on the physical properties of the stimuli, but also on a frame of reference such as other preceding stimuli, a new index of riding comfort is proposed. It is found that this index adding the value of vibration for one block preceding it, is highly effective, and has the correlation coefficient with the rating average is 0.90. This index is also effective for the evaluation of the transition curve which intervenes between straight section and curved section.View full abstractDownload PDF (5841K) -
Am CHO, Kageyu NORO, Tsuneto IWASAKI1997 Volume 33 Issue 6 Pages 357-362
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn this study, we perform a comparative analysis on the physiological changes of the miosis area before and after observing binocular 3D images using liquid crystal shutter glasses under various visual distance (2m and 4m) and indoor illumination levels. The miosis area is measured by an infrared rays optometer. The efficiency of viewing methods of 3D images in the aspect of ergonomics is considered.
From the experiments we obtained the following result:
(1) The miosis area decreases after viewing 2D images and 3D images and the tendency is more critical with 3D images.
(2) The indoor illumination has a significant effect on the miosis area in both 2D images and 3D images. Particularly, it is revealed that the effect is more obvious in 3D images.
(3) Less change of miosis area is observed under the indoor illumination. Thus, if we only focus on the visual load on the eye for viewing 3D images it will be better to use indoor illumination.View full abstractDownload PDF (2738K) -
Toichi SAWADA, Yasuhei OGUCHI1997 Volume 33 Issue 6 Pages 363-370
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn this research, a driving simulator is used to examine, for experimental purposes, how drivers keeping a constant headway distance between themselves and the car ahead can control their vehicles when headway changes. As a result, the following points are identified:
Driver control of the headway distance from the car ahead varies due to headway distance changes. When the distance is 10m, the driver is strained and frequently works on the accelerator pedal. In the case of 20m, the driver begins to relax. When it is 30m, the driver slowly works on the accelerator pedal. Drivers enhance their derivative control action when the headway distance is short, and enhance proportional control action in long headways. Recognition of the relative velocity affects driver behavior to control the distance from the car ahead. In the extent of this experiment, an easy-to-control headway distance is found to be around 20m.View full abstractDownload PDF (4511K) -
Yoshiyuki EGAWA1997 Volume 33 Issue 6 Pages 371-378
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe object of this paper is to evaluate the personal auditory characteristics of loudness by use of many kinds of intermittent noises. First, in order to investigate auditory temporal resolutions for subjects, post masking levels have been measured. As the result of this measurement, the elder subjects have the tendency of higher post masking levels. Next, by use of intermittent noises with different pause durations, the relationship between post masking levels and loudness has been examined. As the result of this experiment, the effect of post masking levels on loudness is observed. This effect is more positive according to long pause durations of intermittent noises. In addition to this, by use of intermittent noises with different sounding durations, the experiment to examine the relation between auditory excitation and loudness level has been conducted. As the result of this experiment, the subjects who have the weekness of auditory excitation tend to estimate the loudness level of those intermittent noises less than the Equivalent Sound Level (hereinafter E. S. L.). Finally, by use of intermittent noises with the same value of E. S. L., the experiment has been conducted. As the result of this, the subjects who have high post masking levels and sharp auditory excitation levels estimate the loudness of these noises louder than the E. S. L.View full abstractDownload PDF (6643K) -
Kenichi KURAI, Takeo IIDA1997 Volume 33 Issue 6 Pages 379-384
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn holding and lifting an object, we estimate the weight of the object through visual information. If two objects are made of the same material and same weight, we lift and perceive one of the larger volume to be lighter than the other of the smaller volume. This phenomenon is an illusion called the Size-Weight Illusion. In this study, we quantified such phenomenon as mentioned above, by means of giving virtual information instead of a real object. The virtual object information given to subjects was only tactile information. To investigate the characteristics of tactile sensation on the perception of the weight of a virtual object, (1) the distance between the two fingers and (2) the grasp force holding the virtual object, were performed. As the results, the force generated weight perceived to be equal to a standard object was clarified to be almost proportional to the square of the grasp width or the grasp force. That is, an object of the same weight was felt lighter when the grasp width or grasp force was increased. It was referred that these characteristics of tactile sensation obtained from the grasp conditions must be considered in handling object in virtual reality.View full abstractDownload PDF (831K) -
Masaharu TAKEDA1997 Volume 33 Issue 6 Pages 385-392
Published: December 15, 1997
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSIn the fatigue investigation decrement in CFF values have been reported to have a causal relationship with physical and mental fatigue and change in the consciousness level of the cerebral center. However, nowadays some investigators have raised suggestion that the decrement in CFF values would reflect a reduction of functions of such regions as the retina and the optic nerve located the peripheral optic chiasm. To examine this question, 8 subjects are tested under the four experimental conditions; three of loading methods of the first rank adding (Kraepelin) work method on CRT, paper, and voice, and the no work method. Under each condition, CFF is measured (by modifying correction method) for 100 minute at intervals of 10minutes. The results of the CFF value decrement are-10.4%/10th time on CRT, -7.0%/9th time on paper, -12.4%/10th time by voice, and -3.1%/11th time for no work. It is supposed that Kraepelin work with voice shows the result from intersively used memory center, compared to the works on the CRT and on the paper. In addition, the load during no work seems to be a reduction of the conscious level of the cerebrum caused by feelings of restriction and tedium. From these results and from the viewpoint of simplicity of measurement as well as judging accuracy, the decrement in CFF values is regarded to be effective as a judging index not for peripheral fatigue of the optical system but also for central fatigue.View full abstractDownload PDF (1205K)
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