• Journal of Broadcast Engineering
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• v.15 no.5
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• pp.607-616
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• 2010

The methods developed to measure visual fatigue so far are quite few and lack of validity, and more importantly, they do not figure out the complex properties of the visual fatigue. The purpose of the research was to analyze the factors comprising the visual fatigue and to develop the method to measure it validly. The results are summarized as follows. First, we found that the 3D visual fatigue was comprised of four independent factors (visual stress, eye pain, body pain and image blurring factors). Second, we developed 29 items that measure four factors of 3D visual fatigue. Finally, the watching duration and binocular disparities affected the visual fatigue as had been expected. These results imply that the developed method does measure the three dimensional fatigue validly.

• Science of Emotion and Sensibility
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• v.19 no.1
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• pp.61-70
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• 2016

3D visual fatigue is known as one of the most important factors that interfere the commercial success of 3D contents. Vergence-accommodation conflict, which is known to occur when an observer watches an image containing binocular disparity presented on a 3D display, has been suggested as a major cause of 3D visual fatigue. This implies that any image incorporating binocular disparity might cause 3D visual fatigue. In order to reduce 3D visual fatigue, it would be necessary to consider indirect ways of reducing 3D visual fatigue as well as eliminating the direct causes of 3D visual fatigue. We have examined the effect of the variables that are expected to affect subjective 3D visual fatigue and these variables included the relative disparity contained in an image, viewing distance and viewing angle. We have also figured out the proper levels of the variables required to minimize 3D visual fatigue. The results indicate that observers began to report significant 3D visual fatigue when the crossed disparity contained in an image exceeded 7.22' and the vertical viewing angle was larger than 15 degree.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.572-583
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• 2012

In this study, we investigated visual fatigue in i3D system and basic factors that contribute to visual fatigue in the system. i3D is a type of glasses-free display which supports elementary manual interaction of users with the display. In Experiment 1, we performed open-ended survey of visual fatigue and collected responses from observers which then were used as survey questions for visual fatigue. The questions were validated by factor analysis from which we derived fatigue measurement scale. In Experiment 2, we measured visual fatigue in various conditions using survey questions obtained from Experiment 1. Using manual interaction (present/absent), viewing distance(1/2/4m), and viewing orientation($0/28/56^{\circ}$) as three factors in within-subject design, we measured visual fatigue in each condition. The results indicated that visual fatigue deceases with farther viewing distance, but viewing orientation and manual interaction does not influence visual fatigue. Although fatigue unexpectedly decreased in an extreme viewing condition (e.g., distance 1m, orientation $56^{\circ}$), the results were obtained because of technical limitation of glasses-free 3D display. General discussion provides discussion on limits of the current study and suggestions for future research.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.1-16
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• 2012

In order to improve the workflow of 3D video production, this paper analyzes the visual fatigue caused from distortions in 3D video production stage through a set of subjective visual assessment tests. To establish a set of objective indicators for subjective visual tests, various distortions in production stage are investigated to be categorized into 7 representative visual-fatigue-producing factors, and to conduct visual assessment tests for each selected category, 4 test video clips are produced by combining the extent of camera movement as well as the object(s) movement in the scene. Each produced test video is distorted to reflect each of the selected 7 visual-fatigue-producing factors, and we set 7 levels of distortion for each factor, resulting in 196 5-second-long video clips for testing. Based on these test materials and the recommendation of ITU-R BT.1438, subjective visual assessment tests are conducted by 101 applicants. The test results provide a relative importance and the tolerance limit of each visual-fatigue-producing factor, which corresponds to various distortions in 3D video production field.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.5
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• pp.191-202
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• 2019

This study examines the effect of luminance contrast ratio of character on readability and visual fatigue during an hour-long reading session while using a tablet PC in ambient environments having low luminance limited to $25cd/m^2$. Experiments were conducted with four patterns of the tablet's luminance contrast ratio of characters, namely 1:2.5, 1:4.5, 1:6.5, and 1:8.5, in low ambient luminance of $9cd/m^2$ and $25cd/m^2$. The obtained results show that the characters can be easily read at the luminance contrast ratio of character of 1:8.5 under surface luminance of $25cd/m^2$. Visual fatigue was evaluated through a subjective survey of symptoms. Physical, psychological, and visual fatigue were observed at a surface luminance of $9cd/m^2$, whereas solely visual fatigue was felt at a surface luminance of $25cd/m^2$. By assessing the physical fatigue using the value, it has been found that smaller the luminance contrast ratio of character, greater is the CFF variation rate. Furthermore, readability is poor and visual fatigue can be observed when the surface luminance is lower than the ambient luminance. However, readability can be improved by increasing the luminance contrast ratio of character to a value of 1:8.5. Thus, in low luminance environments, luminance contrast ratio of characters can affect readability and fatigue. Consider providing the full form of "CFF" so that the acronym can be used unambiguously throughout the manuscript.

• Science of Emotion and Sensibility
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• v.4 no.2
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• pp.63-68
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• 2001

We purpose to evaluate the fatigue of the error correcting task on monitoring with color temperature 2700 K, 4000 K and 6500 K. Results of questionnaire on subjective feeling of visual fatigue, mental fatigue and concentration. Visual fatigue and mental fatigue level were the lowest, concentration level was the highest and working performance was the best at 2700 K. At 6500 K, mental fatigue level was the highest and concentration level is the lowest. At 4000 K, visual fatigue level was the highest and working performance shown the worst ratio of correcting answers. As results, color temperature 2700 K is the best condition of color temperature to perform the error correcting task on monitoring.

• The Journal of Korean Physical Therapy
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• v.26 no.2
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• pp.62-67
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• 2014

Purpose: The purpose of this study was to investigate tibialis anterior muscle fatigue through a Nordic walking when using pole. Methods: This study subject was 38 people who were twenties and randomly assigned to a control group with standard walking and Nordic walking group with Nordic walking. All subjects examined muscle fatigue with surface EMG and visual analogue scale for fatigue. The data were analyzed with SPSS window 18.0 program using ANCOVA. Results: The results were of a significant changes to the both tibialis anterior fatigue(p<0.01). The visual fatigue scales weren't significant difference. Conclusion: It was found that Dool-re-gil (Mt. Ji-Ri) was effective for muscle fatigue during walking, and it appears that it could be used clinically. So it is anticipated that improvement in clinical utilization for the people who's through a Nordic walking when using pole.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.39-46
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• 2016

Loss of postural stability can possibly lead to slip and fall accidents in the number of workplaces and everyday life. This study was aimed to examine the effects of whole body fatigue and partially limited visual field on the ability of maintaining postural balance during quiet standing. A group of twelve healthy male subjects participated in the experiment. Before and after experiencing the whole body fatigue induced by bicycling exercises, the position coordinates of subject's center of pressure (COP) were obtained under the two levels of visual field condition (i.e., open visual field and limited visual field). Four levels of the whole body fatigue examined were rest, 300watt, 600watt, and 900watt. Position coordinates of COPs measured on a force plate were then converted into the total length of postural sway path in both the medio-lateral (ML) direction and the anterior-posterior (AP) direction. Two-way ANOVA result showed that the length of sway path in the AP direction became significantly larger as the whole body fatigue accumulated. Post-hoc test revealed statistically significant differences between rest and 900watt and between 300watt and 900watt. The significant increase of the sway length was also found when the visual field was partially obstructed by the boxes. In the ML direction, however, there was no statistically significant difference of the postural sway in both the AP and ML directions. The results imply that the ability of maintaining postural stability can be reduced significantly due to such tasks along with whole body fatigue. The postural balance can also be impaired by the limited visual field.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.3
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• pp.67-71
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• 2017

PURPOSE: Muscle fatigue is a cause to change proprioception. The purpose of this study was to investigate the effects of calf muscle fatigue and visual control on postural balance during single-legged standing in healthy adults. METHODS: Nineteen healthy adults (male) were participated in this study (mean age: 24.36 years; mean height: 171.32 cm; mean weight: 64.58 kg). The postural balance (sway length, sway area, sway velocity of COG displacement) was measured by Balance Trainer System (BT4) in before and after calf muscle fatigue feeling in single legged stance. In this study, repetitive single-legged heel rise test was used to induce fatigue of the calf muscle. Paired t- test was used to compare the postural balance between before and after calf muscle fatigue. Data of subjects were analyzed using SPSS 22.0 (SPSS Inc., Chicago, IL, USA). Level of significance was set to .05. RESULTS: The sway length, sway area, sway velocity of COG (center of gravity) displacement after calf muscle fatigue feeling was significantly increased compared to before calf muscle fatigue feeling during single leg standing both eye open and close conditions (p<.05). CONCLUSION: This study suggested that calf muscle fatigue feeling has affected on postural balance when standing one leg both eye open and close conditions and postural control was disturbed by muscle fatigue and visual feedback in single leg standing.

• Science of Emotion and Sensibility
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• v.15 no.1
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• pp.17-28
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• 2012

Recent development of 3D technologies made it possible that observers perceive 3D depth from two dimensional images. Despite this kind of technological development, when observers watch 3D display they experience 3D visual fatigue that they do not usually experience in real life. It is critical to measure visual fatigue in order to overcome the problem of 3D visual fatigue. The purpose of the present study was to develop a protocol to measure 3D visual fatigue based on an EEG signal and to examine its validity. The first experiment explored the possible ERP components that reflected visual fatigue in 2D and 3D conditions. The second experiment examined whether the feature of the component found in the first experiment was affected by the amount of binocular disparity. Both in Cz and Pz channels, the peak amplitude of P3 component was much lower in 3D rather than in 2D conditions, and it decreased as the amount of binocular disparity increased. The subjective 3D visual fatigue also increased with the amount of binocular disparity. These results imply that the peak amplitude of P3 component at Cz and Pz channels can be used as an index of 3D visual fatigue.