• Journal of the Korean Society of Clothing and Textiles
• /
• v.43 no.3
• /
• pp.373-383
• /
• 2019

This research investigated the effect of individual yarn colors on the perception of overall colors of yarn-dyed woven fabrics. The way the colors of yarn-dyed woven fabrics are perceived is known as visual color mixing: when the different colored yarns juxtaposed on the fabric surface are observed from some distance away, they are visually mixed in our eyes and perceived as a solid color. However, we can still see individual yarn colors that make the fabrics look obviously different from actual solid colors. To quantify this visual color mixing effect, twenty-one sateen fabrics were produced in a wide range of colors using cyan, magenta, and yellow yarns, and the colors were measured instrumentally. The obtained colorimetric values were converted into solid color images on a CRT monitor. Then, the physical fabrics were scanned, and the scanned images were displayed on the monitor with solid color images in pairs for visual color difference evaluation. The woven and solid colors in each pair were of physically identical color; however, the visual color difference was as large as $4.81{\Delta}{E^*}_{ab}$ on average. A visual color difference model was proposed by considering this parametric effect of individual yarn colors.

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

• PNF and Movement
• /
• v.16 no.2
• /
• pp.179-185
• /
• 2018

Purpose: This study aimed to analyze the visual and spatial elements of the gait of a stroke patient who had diverse ankle weight loads applied, according to weight changes. Methods: The subject was a 57-year-old stroke patient diagnosed and hospitalized with a left intracerebral hemorrhage. A weight equivalent to 0%, 1%, and 2% of his body weight was applied to the area 5cm upward from the ankle using a Velcro strap. He was then trained on a treadmill, receiving a six-minute walk test to evaluate his gait ability. A gait analyzer was used to collect visual and spatial elements, such as gait distance, gait velocity, cadence, step length, stride length, and swing phase, according to a weight load equivalent to 0%, 1%, and 2% of his body weight. Results: According to the results of applying 0%, 1%, and 2% of his body weight on the ankle, except for gait velocity, his gait distance, cadence, step length, stride length, and swing phase were higher when 1% of his body weight was applied compared to 0% or 2% of his body weight. Conclusion: Applying a weight equivalent to 1% of the body weight to the ankle positively affected the visual and spatial element of the gait and heightened the efficiency of exercise during treadmill training, a gait-training tool generally used for stroke patients. However, the result is difficult to generalize because the number of subjects was small with only one subject.

• Transactions on Control, Automation and Systems Engineering
• /
• v.4 no.4
• /
• pp.341-346
• /
• 2002

When a construction company builds a high structure. many piles should be driven into the ground by a hammer whose weight is 7,000 kg in order to make the ground under the structure safe and strong. So. it is essential to determine whether a pile is penetrated into the ground enough to support the weight of the structure since ground characteristics at different locations are different each other. This paper proposes a visual measurement system for pile rebound and penetration movement including vibration using a high-speed line-scan camera and a specially designed mark to recognize two-dimensional motion parameters of the mark using only a line-scan camera. A mark stacking white and black right-angled triangles is used for the measurement, and movement information for vertical distance, horizontal distance and rotational angle is determined simultaneously. Especially- by adopting a line-scan CCD camera whose line rate is 20 ㎑. the measurement performance of dynamic characteristics of the pile at impact instant is improved dramatically.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.145-148
• /
• 1996

In moving object tracking based on the visual sensory feedback, a prerequisite is to determine which feature or which object is to be tracked and then the feature or the object identification precedes the tracking. In this paper, we focus on the object identification not image feature identification. The target identification is realized by finding out corresponding line segments to the hypothesized model segments of the target. The key idea is the combination of the Mahalanobis distance with the geometrica relationship between model segments and extracted line segments. We demonstrate the robustness and feasibility of the proposed target identification algorithm by a moving vehicle identification and tracking in the video traffic surveillance system over images of a road scene.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.10
• /
• pp.1871-1878
• /
• 2015

Recently, research on the Visual-MIMO by applying the concept of MIMO to communication between the LED array and camera is in progress. Although we already introduced the method for bit decision by using reference LED array pattern, it has the disadvantage of measuring the ISI each time when there is a change in the distance. To overcome this, in this paper, we propose a bit decision and error correction method used by using the luminance deviation without using the reference array pattern. First, we execute the bit decision using experimentally determined threshold. Next, we execute the error checking on the ON-LED and make a correction only if it is found to be error. Correction is determined by using the value of brightness deviation corresponding to the range of 68.2% (1) around the maximum frequency of the histogram for each ON-LED. We verify the performance of the proposed method according to the variation of ISI with distance by using both numerical and experimental analysis.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.1
• /
• pp.51-60
• /
• 2011

Purpose: This study was to investigate visual performance and subjective satisfaction with multifocal soft contact lenses at near works in university students. Methods: In a cross-over study design, 26 students (6 male, 20 female) who did not have any ocular disorder with at least 20/20(1.0) binocular vision were fitted with singlevision lenses (SofLens$^{TM}59$, Bausch + Lomb Co. USA) or multifocal lenses (SofLens Multifocal, Bausch + Lomb Co. USA). After 2 weeks, visual performance assessments included visual acuity, stereoacuity and contrast sensitivity function at distance and near. Near point of accommodation, accommodative facility, near point of convergence, vergence facility and near range of clear vision at near were examined. Students' satisfaction and preference were measured using survey questionaries. Results: Subjects maintained at least 20/20 binocular vision with multifocal and single-vision lenses at distance and near. There was no difference between multifocal and single-vision lenses in stereoacuity, contrast sensitivity function and vergence facility at far and near. The near point of accommodation, accommodative facility, near point of convergence and the near range of clear vision with multifocal lenses were better than single-vision lenses. On the survey questionaries, subjects reported that they preferred and satisfied with multifocal lenses with near works, and single-vision lenses with distance works. Conclusions: The majority of university students preferred multifocal to single vision lenses because multifocal lenses provided better visual performance at near works. This study suggests that multifocal lens is helpful for young adult in prolonged near works.

• Science of Emotion and Sensibility
• /
• v.12 no.2
• /
• pp.169-180
• /
• 2009

The present study have investigated the effect of the characteristics of stereoscopic images and viewing environment on visual fatigue. We manipulated the speed of stereo images with motion-in-depth and viewing distance, which were used as representative variables of the characteristics of stereo image and viewing environment, respectively. Visual fatigue was evaluated with use of a subjective questionnaire which is consisting of 5 different and independent factors: "Eye pain", "Visual stress," "Nauseousness", "Body stiffness", and "Blurriness". In general, when viewing time increased from 10 minutes to 20 and 40 minutes, observers felt severe visual fatigue. Among other factors, only the factor score of "Nauseousness" was significantly increased as the speed of object moving in depth became faster. When viewing distance was increased, the score of "Blurriness" was decreased. These results suggest that different kind of the visual fatigue might be induced depending on characteristics of the stereo images and viewing environment.

• Journal of Korean Medical Science
• /
• v.33 no.44
• /
• pp.275.1-275.15
• /
• 2018

Background: We compared the efficacy between trifocal and bifocal diffractive intraocular lens (IOL) implantation. Methods: Through PubMed, MEDLINE, EMBASE, and CENTRAL, we searched potentially relevant articles published from 1990 to 2018. Defocus curves, visual acuities (VAs) were measured as primary outcomes. Spectacle dependence, postoperative refraction, contrast sensitivity (CS), glare, and higher-order aberrations (HOAs) were measured as secondary outcomes. Effects were pooled using random-effects method. Results: We included 11 clinical trials, with a total of 787 eyes (395 subjects). The trifocal IOL group showed better binocular distance VA corrected with defocus levels of -0.5, -1.0, -1.5, and -2.5 diopter than the bifocal IOL group (All $P{\leq}0.004$). The trifocal IOL group showed better monocular uncorrected distance and intermediate VAs (mean difference [MD], -0.04 logarithm of the minimum angle of resolution [logMAR]; 95% confidence interval [CI], -0.07, -0.01; P = 0.006 and MD, -0.07 logMAR; 95% CI, -0.13, -0.01; P = 0.03, respectively). Postoperative refraction, glare, CS, and HOAs were not significantly different from each other. Conclusion: The overall findings indicate that trifocal diffractive IOL implantation is better than the bifocal diffractive IOL in intermediate VA, and provides similar or better in distance and near VAs without any major deterioration in the visual quality.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.12
• /
• pp.699-707
• /
• 2014

Recently, the communication between LED array and camera, called Visual-MIMO, is under active research and we expect the maximization of application to the vehicle as well as smart-phone. In this paper, we improve the BER performance of Visual-MIMO system by using the brightness information of a received image. We also suggest the error correction method to minimize the error due to Inter-Symbol-Interference. The performance analysis according to the noise and distance variation will verify the validity of our proposed method including results through simulation and hardware experiment.