• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.219-228
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• 2015

Purpose: The current study was performed to compare the difference in binocular visual function depending on variable background colors at near work. Method: Fifty four adults (18 males, 34 females) who consented to the present study and had no ocular disease, ocular surgery history, strabismus and amblyopia with normal binocular vision were participated into this study. The subjects were asked to read the novels with black letter printed on white, red, green and blue background for 15 min. Then, their heterophoria, AC/A ratio, near point of convergence, accommodation facility, relative accommodation and vergence were measured before and after reading. The difference of measurements were compared. Result: Overall heterophoria was tended to decrease with regardless of background color. AC/A ratio showed a tendency of increase after reading the novels with all backgrounds except white background. Near point of convergence was significantly increased compared to before reading at all background color. Accommodative facility of dominant and non-dominant eyes were also significantly increased after reading however, binocular accommodative facility showed a tendency of decrease. Negative relative accommodation also decreased at all background colors however, the change of positive relative accommodation was not significantly different. In case of vergence, there was significant difference in break point of far BO and recovery point of far BI by the wavelength of background color. Conclusions: From the results, it was known there is convergence change depending on the wavelength of light even though same amount of accommodation and convergence is required when doing near work for certain period. Thus, it can be suggested that the adjustment of the near working environment which perception of various color was required, should be conducted according to the main wavelength.

• Journal of the Korea Convergence Society
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• v.13 no.2
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• pp.55-65
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• 2022

The purpose of this paper was to investigate the relationship between cybersickness symptoms and visual function and to determine whether visual perception training is effective in reducing symptoms of cybersickness. The study subjects were healthy adult males who experienced the same virtual reality program for 15 minutes. Afterwards, the VR satisfaction score and cybersickness level were measured and classified into a comfortable virtual reality program viewer group (CVR group, 20 people) and an uncomfortable virtual reality program viewer group (UVR group, 20 people). Visual function test was performed on all subjects, and the vision therapy training program was applied to the UVR group once a week for 40 minutes 12 times, and then the visual function and SSQ questionnaire were re-evaluated. Subjects with diplopia were 55% in the UVR group and 5% in the CVR group, which was significantly higher in the UVR group, there were differences in stereopsis, exophoria, near point convergence(p<.01) and vergence function(p<.001) between the two groups. After vision therapy, changes in SSQ, stereopsis, near point convergence, and vergence function of UVR user group were positively changed(p<.01). Therefore, cybersickness symptoms are related to visual function, it seems that the vision therapy can be used as a way to alleviate the symptoms of cybersickness.

• ETRI Journal
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• v.40 no.3
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• pp.366-375
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• 2018

Recently, techniques involving head-mounted displays (HMDs) have attracted much attention from academia and industry owing to the increased demand for virtual reality and augmented reality applications. Because HMDs are positioned near to users' eyes, it is important to solve the accommodation-vergence conflict problem to prevent dizziness. Therefore, holography is considered ideal for implementing HMDs. However, within the Nyquist region, the accommodation effect is limited by the space-bandwidth-product of the signal, which is determined by the sampling number of spatial light modulators. In addition, information about the angular spectrum is duplicated over the Fourier domain, and it is necessary to filter out the redundancy. The size of the exit-pupil of the HMD is limited by the Nyquist sampling theory. We newly propose a holographic HMD with an expanded exit-pupil over the Nyquist region by using the time-multiplexing method, and the accommodation effect is enhanced. We realize time-multiplexing by synchronizing a high-speed digital micromirror device and a liquid-crystal shutter array. We also demonstrate the accommodation effect experimentally.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.157-159
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• 2013

3D 산업은 그 실용적인 활용가치로 인해 주목받고 있다. 안정적인 3D 시청환경을 구축하기 위해서는 구현기술의 발전이 중요한 과제이지만, 현재의 기술 수준이 제한적이기 때문에 사용자가 시청환경에 대해 주관적으로 느끼는 부분을 다루는'휴먼팩터 (Human-factor)'를 연구하는 것 또한 중요하다. 그 중 시각피로는 안정적인 3D시청환경 구축과 직결되는 중요한 문제이며, 이러한 시각피로의 주요원인은 수렴-조절 불일치 현상이다. 본 연구는 수렴-조절 불일치에 직접적인 영향을 미치는 것이 화면시차 자체가 아니라 수렴각에 영향을 미치는 응시대상의 화면시차라고 가정하였다. 따라서 응시대상의 화면시차가 3D상황에서 수렴조절 불일치를 유발하는지를 규명하기 위하여 시청자들을 대상으로 응시대상의 화면시차를 조작하면서 그것이 시각피로에 영향을 주는지를 측정하였다. 결과는 예상대로 다른 대상들보다 응시대상의 시차가 시각피로에 주요한 영향력을 준다는 것을 함축하고 있으며, 그 외에 비-응시대상과 관련된 이슈들이 논의되었다. 결론적으로, 응시대상의 시차를 적절하게 통제함으로써 사용자의 시각피로를 최소화 할 수 있으며, 이는 시각 3D 환경을 구축하는 데에 도움이 될 것이다.

• Journal of KIISE:Information Networking
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• v.28 no.2
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• pp.236-241
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• 2001

A new scheme is proposed to speed up a known bandwidth measuring method which employs potential bandwidth for filtering out noiscs (in cstirna60nl from time compression caused by a packet queueing ahead of two probe packets. Instead of inerementing the potential bandwidth by a fixed amount as in the original method we increase the potential bandwidth exponentially for faster convergence. To retain its filtering capability as well as its agility to adapt to new bottleneck bandwidth, each trial potential bandwidth(PB) is adjusted using MAX and MIN as upper bound and lower bound. An experiment using known bandwidths shows 45~g9% improvement in conVergence time.

• Annals of Clinical Neurophysiology
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• v.1 no.2
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• pp.173-181
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• 1999

Eye movements serve vision by placing the image of an object on the fovea of each retina, and by preventing slippage of images on the retina. The brain employs two modes of ocular motor control, fast eye movements (saccades) and smooth eye movements. Saccades bring the fovea to a target, and smooth eye movements prevent retinal image slip. Smooth eye movements comprise smooth pursuit, the optokinetic reflex, the vestibulo-ocular reflex (VOR), vergence, and fixation. Saccades achieve rapid refixation of targets that fall on the extrafoveal retina by moving the eyes at peak velocities that can exceed $700^{\circ}/s$. Various brain lesions can affect saccadic latency, velocity, or accuracy. Smooth pursuit maintains fixation of a slowly moving target. The pursuit system responds to slippage of an image near the fovea in order to accelerate the eyes to a velocity that matches that of the target. When smooth eye movements velocity fails to match target velocity, catch-up saccades are used to compensate for limited smooth pursuit velocities. The VOR subserves vision by generating conjugate eye movements that are equal and opposite to head movements. If the VOR gain (the ratio of eye velocity to head velocity) is too high or too low, the target image is off the fovea, and head motion causes oscillopsia, an illusory to-and-fro movement of the environment.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.181-186
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• 2000

The setup of the moir$\acute{e}$ deflectometry using the virtual grating was done, so the convergence and divergence of a pencil of ray was determined. The light source was He-Ne laser(3mW). The focal length of the first lens, the second lens being 18 mm, 250 mm respectively was used for the setup of the beam expander. The optics of the moir$\acute{e}$ deflectometry determining the vergence was used a diffraction grating(pitch = $1.6{\mu}m/line$) and a front flat reflection mirror. The effective focal length of the trial lens set was measured and compared with the theoretical value.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.79-84
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• 2001

This paper present the control of the image disparity of a parallel stereo camera and its application to an underwater stereo camera to enhance the working efficiency of underwater vehicles that are equiped with manipulators in seabed operation. The stereo camera consists of two parallel lenses mounted on a lateral moving base and two CCD cameras mounted on a longitudinal moving base, which is embedded in a small pressure canister for underwater application. Because the lateral shift is related to the backward shift with a nonlinear relation, only one control input is needed to control the vergence and focus of the camera with a special driving device. We can get clear stereo vision with the camera for all the range of objects in air and in water, especially in short range object. The control system of the camera is so simple that we are able to realize a small stereo camera system and apply it to a stereo vision system for underwater vehicles. This paper also shows how to acquire the distance information of an underwater object with this stereo camera. Whenever we focus on an underwater object with the camera, we can obtain three-dimensional images and distance information in real-time.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.95-101
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• 2008

Purpose: The aim of this research was to propose a program that can be used the Binocular Eye Visual Perception Training. Methods: This program can be used as a tool for binocular vision and vision training. The system that was made up of module was available in the stereosis and the vergence training. Results: In case of input module, this program could estimate the distance by using fixation disparity. Also, our margin of erroe is less then 5%. In case of output module, 28 trainers were examined by stereoscopic vision and visual depth perception. Conclusions: Therefore, the system can be used as a tools for the vision training.

• 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.