• Journal of the Ergonomics Society of Korea
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• v.36 no.4
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• pp.293-303
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• 2017

Objective: This study aims to evaluate visual discomfort and visual fatigue caused by watching HMD and smartphones by conducting both subjective and objective measure. Background: With the rapid development of mobile Head-Mounted Display (HMD), the problem of visual discomfort and visual fatigue caused by watching Virtual Reality (VR) contents became a crucial concern for consumers and manufacturers, especially given that the casing of mobile HMD keeps the phone at a specified distance from the lenses that is close to the eyes. Method: Two smartphones were chosen for a preliminary study: LG G5 and Galaxy S7. As for a main study, iPhone 6S and Galaxy S7 were used. After being exposed to the selected clips, participants were asked to answer Simulator Sickness Questionnaire (SSQ) and went through optometric tests that measure tear break-up time, spherical equivalent, and contrast sensitivity. Results: The subjective assessments indicate that HMD causes more visual discomfort compared to watching a smartphone. Furthermore, the experimental result confirms that watching a HMD causes more eye dryness compared to smartphones. Conclusion: The result of the study compared visual discomfort and visual fatigue of two different displays, HMD and smartphone, and confirmed that watching HMD causes more visual discomfort and visual fatigue. Application: Ultimately, this study could help manufacturers understand the strengths and weaknesses of different display forms, providing guidance for an effective application of HMD.

• Journal of Korea Multimedia Society
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• v.19 no.9
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• pp.1723-1737
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• 2016

When watching 3D contents, people often experience various visual discomforts like tiredness, dryness, headaches, and dizziness. Previous researches on visual discomfort analyzed and concluded vergence-accommodation conflict, viewing distance, and brightness changes to be the causes of visual discomfort. Yet it is necessary to systematically analyze the visual discomfort due to the changes in object, background brightness and viewing distance. In this paper, we produce four videos that have four different background brightness and two different viewing distances to solve analyze the visual discomfort from watching 3D contents. We measure and analyze eye-blink and saccadic movement, saccadic latency, Nearest Point of Convergence (NPC), and participant survey for amore accurate result compared to previous researches. Our results show that the eye-blink rate and saccadic latency increase when the background is bright and viewing distance is close while the saccadic movement decreases in the same environment. However, NPC only changes when the background brightness changes. We confirm that the bright background and near viewing distance create greater visual discomfort and decrease depth perception abilities.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.10
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• pp.16-26
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• 2012

This study conducted a subjective evaluation of brightness perception and visual discomfort according to dimming speeds and CCTs(Correlated Color Temperatures). Dimming speeds of two different CCT lights(2,700K, 6400K) were set to 1.7%/s, 3.3%/s, 5.0%/s, 6.7%/s, and 10.0%/s respectively. Subjects checked the time when they perceived the change of the brightness and visual discomfort. As a result, when dimming speeds were 1.7%/s, 3.3%/s, 5.0%/s, 6.7%/s, more than half of subjects responded the change of the brightness in 55.0~45.0% dimming ratios, and felt the visual discomfort in 35~25% dimming ratios. When the brightness was changed, dimming level responded to the brightness perception of hight CCT(6,400K) was higher about 8.0% then dimming level responded to the brightness perception of low CCT(2,700K). Dimming level responded to the visual discomfort of low CCT(2,700K) was higher about 5.0% then dimming level responded to the visual discomfort of hight CCT(6,400K).

• Journal of Broadcast Engineering
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• v.18 no.5
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• pp.738-748
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• 2013

The present study investigated whether convergence training in which has an effect on reducing visual discomfort in viewing 3D TV. The stereoscopic depth of 3D training stimulus was gradually increased while maintaining individual visual discomfort at a minimum value. Participants were randomly assigned into one of three groups: a control group and two training groups. For both training groups, all procedure and the disparity range of training stimuli were the same except the order of the disparities of training stimuli. One of the two different training procedure was provided: gradual change or random change of the disparities of training stimulus. Training itself was very effective so that convergence fusional range was improved after three sessions of training with intervals of two weeks. In order to evaluate the effect of convergence training on visual discomfort, the subjective visual discomfort in 3D TV viewing was measured before and after training sessions using questionnaire. The results showed that a significant reduction in visual discomfort was found after training only in the group of gradual change. These results demonstrated a repeated convergence training might be helpful in reducing the visual discomfort in 3D TV environment.

• Journal of Korean Biological Nursing Science
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• v.26 no.2
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• pp.111-122
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• 2024

Purpose: Visual impairment, hearing impairment, and masticatory discomfort each influence quality of life (QoL). However, little is known regarding the impact of their coexistence on QoL. Therefore, we aimed to investigate the influence of the coexistence of visual impairment, hearing impairment, and masticatory discomfort on QoL among middle-aged adults aged 40-64. Methods: This study involved a secondary data analysis utilizing the data from years 1 and 2 of the eighth Korea National Health and Nutrition Examination Survey. To evaluate the influence of the coexistence of visual impairment, hearing impairment, and masticatory discomfort on QoL, we conducted a complex sample hierarchical multiple regression analysis. Results: When visual impairment, hearing impairment, and masticatory discomfort coexisted, the QoL was significantly lower than in individuals without any of these conditions. Conclusion: The coexistence of visual impairment, hearing impairment, and masticatory discomfort was negatively correlated with QoL. Therefore, it is important to prepare for old age through appropriate health management during middle age.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.91-99
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• 2009

A visual stress may provoke migraine, cephalalgia, intervene a long term reading and learning capability and reduce the productivity of a laborer who uses computer for a good while. In this study, a web based screening tool for visual stress was developed, it applied to 72 visually normal young persons in parallel with traditional questionnaire about symptoms of visual stress. To estimate visual stress, It is proposed to measure difference of visual search time of Han Gul characters as targets between visual stressful pattern and non-visual stressful pattern as global background of characters. As a result of test, 5 subjects were screened whose mean visual search time in the stressful pattern with 6 CPD spatial frequency increase significantly more than in none stressful pattern(t-test, one-tailed, p=$1.0407\times10^{-11}$). 2 of them were diagnosed as mild visual stress syndrome in the clinic. None had visual distortion and 50% of subjects had visual discomfort in results of the questionnaire. Correlation between visual search time increase rate and normalized number of visual discomfort may be slight(C. coefficient=0.1355). This study may contribute as a basic research for screening person with migraine, visual reading disabilities and VDT syndrome. It is required to apply the test to visual reading disabilities, migraine with visual distortion and/or visual discomfort as well as normal person for higher reliability of the screening tool.

• KIEAE Journal
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• v.7 no.6
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• pp.37-43
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• 2007

Discomfort glare is an important factor influencing appraisal for lighting environment. Unified Glare Rating (UGR) which has been proposed by CIE is one of the formula for evaluating discomfort glare. Position index is an important factor in the UGR formula. Position index was proposed by Guth in 1949. It has been used until present limiting upper visual field. Lower visual field has different sensation of brightness in comparing with upper visual field. Therefore, it is necessary to propose position index about lower visual field. The objective of this study is to investigate the brightness sensation in upper and lower visual field. First, the visual field was measured on the self-made Glare Tester. Second, luminance of the Borderline between Comfort and Discomfort (BCD) was measured on the glare Tester. Circular sources of brightness were located at various angular distances from the line of vision along five meridians, $0^{\circ}$, $45{\circ}$, $90{\circ}$, $-45{\circ}$, $-90{\circ}$. The size of the glare source is 0.0011sr. The luminance of the surrounding field, which extended over the entire visual field, was maintained $34ccd/m^2$. Ten subjects aged from 25 to 29 were participated in the experiment. The results show that the luminance of BCD on the line of vision is $4337cd/m^2$ and the glare sensation of the lower visual field is more sensitive than the upper visual field.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2012.05a
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• pp.132-133
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• 2012

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.888-890
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• 2017

VR browser is one of the most popular applications for VR(Virtual Reality) environment. However, because most of the web contents are not designed considering the VR environment, scrolling the web pages in the VR browser causes much visual discomfort. We found it's because the angular velocity of the eye movement during scrolling increased because the viewing distance got closer compared with legacy devices. So we have developed a technology that regulates the scrolling to reduce the visual discomfort in the VR browser, in reference of the visual perception characteristics of the human visual system.

• Current Optics and Photonics
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• v.4 no.6
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• pp.540-544
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• 2020

Current two-dimensional (2D) augmented reality (AR) devices present virtual image and information to a fixed focal plane, regardless of the various locations of ambient objects of interest around the observer. This limitation can lead to a visual discomfort caused by misalignments between the view of the ambient object of interest and the visual representation on the AR device due to a failing of the singular fusion. Since the misalignment becomes more severe as the depth difference gets greater, it can hamper visual understanding of the scene, interfering with task performance of the viewer. Thus, we analyzed the range of singular fusion (RSF) of AR images within which viewers can perceive the shape of an object presented on two different depth planes without difficulty due to the failure of singular fusion. It is expected that our analysis can inspire the development of advanced AR systems with low visual discomfort.