• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.52-57
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• 1997

We report an investigation of the statistical fluctuations of the two-mode laser output as the asymmetry parameter is varied. The above results relate to computer solutions of the coupled Langevin equations both with and without pumping fluctuations. We find that as the asymmetry parameter is changed positively, the mean intensity of one mode is increased because the normalized intensity auto-correlation is decreased so that the natural dwell time is lengthen. The laser output does respond to a sinusoidally injected asymmetry parameter for small pump parameter.

• Journal of information and communication convergence engineering
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• v.19 no.3
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• pp.180-187
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• 2021

In this paper, we present a computational volumetric reconstruction method for three-dimensional (3D) photon counting imaging with enhanced visual quality when low-resolution elemental images are used under photon-starved conditions. In conventional photon counting imaging with low-resolution elemental images, it may be difficult to estimate the 3D scene correctly because of a lack of scene information. In addition, the reconstructed 3D images may be blurred because volumetric computational reconstruction has an averaging effect. In contrast, with our method, the pixels of the elemental image rearrangement technique and a Bayesian approach are used as the reconstruction and estimation methods, respectively. Therefore, our method can enhance the visual quality and estimation accuracy of the reconstructed 3D images because it does not have an averaging effect and uses prior information about the 3D scene. To validate our technique, we performed optical experiments and demonstrated the reconstruction results.

• Korean Journal of Optics and Photonics
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• v.19 no.6
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• pp.389-393
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• 2008

Enhanced reconstruction of heavy occluded objects was represented using estimation of variance in computational integral imaging. The system is analyzed to extract information of enhanced reconstruction from an elemental images set. To obtain elemental images with enhanced resolution, low focus error, and large depth of focus, synthetic aperture integral imaging (SAII) utilizing a digital camera has been adopted. The focused areas of the reconstructed image are varied with the distance of the reconstruction plane. When an occluded object is occluded heavily, an occluded object can not be reconstructed by removing the occluding object. To obtain reconstruction of the occluded object by remedying the effect of heavy occlusion, the statistical technique has been adopted.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.117-120
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• 2007

The actual condition of periodic visual acuity testing for 304 undergraduate students were investigated for the purpose of prepared some fundamental data on the development of the eye-health education program and conducting a practical application. Many undergraduate students (59.21%) had not been tested periodic visual acuity testing. The ratio of periodic visual acuity testing for female was higher than male. There was statistical significant difference dependence on the native place, the educational system, and the division of major. The ratio of periodic visual acuity testing for undergraduate students from city was 43.07%, from rural area was 24.32% (p<0.05). According to the educational system, the ratio of periodic visual acuity testing of university students was 65.71%, college students was 27.64% (p<0.001). The ratio of periodic visual acuity testing of undergraduate students who have corrected their visual acuity was 50.25%, while that of students who have not corrected was 23.36% (p<0.001).

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.49-53
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• 2007

In this paper, for the purpose of preparing some fundamental data on the development of the eye-health education program and conducting a practical application, the degree of request for the eye-health education were investigated by surveying 304 undergraduate students. The relationship between the degree of request for the eye-health education and sex, the division of major, and the experience of eye-health education was examined by SAS and $X^2$-test of questionnaire. The degree of request of undergraduate students for the eye-health education was as high as 86.51%. There was no statistical significant difference dependence on their experience of the eye-health education or their sex. There was significant difference dependence on their major. Specially, the degree of request of natural science, medical and health science majors was higher than any other majors. Consideration on the eye-health education should be required to meet the request of it.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.195-202
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• 2012

Purpose: We intended to study effects of wearing the progressive lenses on legibility of Korean letters under the VDT circumstance. Methods: Fifty subjects wearing the progressive lenses and the single focus lenses were asked to find designated characters on web-pages under the VDT circumstance. We measured times for subjects to read the web-pages and numbers of missed characters, considering them as standards of legibility, and compare results of the progressive lenses with those of the single focus lenses by variables of the size and legibility of letters and the width of web-pages. Results: In case of the progressive lenses, all the times to read the web-pages and some of the numbers of missed characters increased with statistical significance. Smaller the character size, lower the legibility of character itself, and wider the width of web-page, the legibility tended to be seriously lowered by the progressive lenses. Conclusions: It is presumed that the intermediate part of progressive lenses with narrow visual field lowers the legibility of Korean letters under the VDT circumstance.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.107-112
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• 2008

urpose: This thesis is a study the Night myopia was surveyed by Subjective refraction and Objective refraction (Dark retinoscopy), and analyzed the relationship between them. It also looked at the relation between Night myopia and pupil size. Methods: 82 adult subjects (ages of 19 to 44, 44 males and 38 females) were examined by Subjective refraction and Objective refraction in the light place. Then Night myopia and pupil size were examined by Subjective refraction and Objective refraction in the dark again. The Statistics were analyzed by SPSS (Statistical Package for Social Science). Results: As the subjects became younger, the observed Night myopia was getting higher in both Subjective refraction, $x^2$=219.48 (p<0.01) and Objective refraction, $x^2$=241.98 (p<0.01). The relationship was statistically significant by showing large pupil size, $x^2$=151.74 (p<0.01). In Objective refraction, as pupil size became larger in the dark place, so did Night myopia, $x^2$=84.27 (p<0.01), reaching a statistically significant correlation, however, the correlation was low in Subjective refraction. In Subjective refraction, observed Night myopia was 73%, 64 examples of 88 examples, a standard of 0.96${\pm}$0.4584D in ${\pm}$0.25D, in male examples, and it was 64%, 49 examples of 76 examples, a standard of 1.01${\pm}$0.4509D in ${\pm}$0.25D, in female examples. In Objective refraction, it was 48%, 42 examples of 88 examples, in standard of 0.85${\pm}$0.4651D in ${\pm}$0.25D, in male examples. And it was 71%, 54 examples of 76 examples, in standard of 0.96${\pm}$0.4133D in ${\pm}$0.25D, in female examples. Conclusions: Night myopia which is measured by both methods, observed as $x^2$=265.35 (p<0.01) and showed a large relationship. The correlation between the two refractions suggests that observed night myopia diopter by Subjective refraction could be used as correction of night myopia.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.263-268
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• 2010

Purpose: Eye movements and fixation ability are an important procedure to obtain external information and essential means of clear vision. The purpose of this study was to determine the reading performance such as reading time and number of fixations when random text was viewed at varying distances. Methods: Twenty two presbyopes were participated. All subjects were screened for their suitability to participate in the study by clinical examination, and none of the participants had previously worn contact lenses and no previous experience of wearing any types of presbyopic vision correction except single vision. The reading time and number of fixations were recorded using eye tracker while each subjects was waring four vision corrections which included single vision for distance (SV), bifocal spectacle lenses (BIF), progressive addition lenses (PAL), and monovision (MV). The reading material was presented at distance and near distance. Results: Reading time and number of fixations for near stimulus were significantly different among vision correction used in this study (p<0.001). In particular, wearing SV required longer reading time and produced longer fixation duration for near text. However, reading distance text was similarity performed across vision corrections tested and there was no statistical difference found for either reading time and number of fixations. Conclusions: Wearing presbyopic vision correction is advantageous for reading task of near stimuli, but not having near correction such as wearing SV could result in longer reading time and higher number of fixation due to lacks of accommodative ability for near task. For the future studies, it would be interesting to examine the performance of reading both at adapted and unadapted stages as examining only unadapted wearers was limitation of this study.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.59-65
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• 2012

Purpose: The purpose of this study was to determine the distribution and correlation of accommodative lag with refractive error. Method: We had tested the clinical refraction and the accommodative lag in clinically normal 49 young adults (total 98 eyes) aged 18 to 25 years without abnormal binocular function. Monocular and binocular accommodative lag were tested with 0.50 D cross-cylinder lens and near vision test chart which had cross-hairs after full correction of LogMAR visual acuity over 0.05. Results: There was no statistical differences in monocular accommodative lag between right ($0.64{\pm}0.64$ D) and left eye ($0.63{\pm}0.64$)(p=0.858). The accommodative lag of male was higher than female and the range of the value was broader than female in binocular accommodative lag (p=0.015). The wider the inter-pupillary distance was, the higher the accommodative lag was (p=0.003). However, there were no differences with age (p=0.800) and dominant eye (p=0.402). The ranges of accommodative lag of low, middle, and high myopia were 0.75 ~ -0.25 D, 1.25 ~ -0.50 D, and 1.50 ~ -0.75 D, respectively, and the regression was 'y = -0.03953x+0.09205'. Conclusions: These data suggest that clinically normal young adults with high amounts of refractive error have more variable accommodative lag and increased spherical equivalent refraction.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.173-179
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• 2016

Purpose: This study is to help assist in the management of optical shops by using the importance sequence of optical shop selection attributes, which is related to the consumer's selection method of consumer, and by using the importance sequence of optical shop information sources which is related to a route for optical shop selection. Methods: Customer surveys were conducted from March 10 to March 31, 2015 targeting customers who have visited an optical shop in Seoul and Northern Gyeonggi-do regions. The analys method was descriptive statistics and data were analyzed by utilizing SPSS v.10.0 statistical package program. Results: The highest ranking five attributes among the importance of optical shop selection are "friendliness and politeness of staff", "cleanliness of an optical shop", "quick resolution of customer's complaints by staff", "eyes examination and glasses dispensing skill of staff", "customer's complaints and claims handling". The lowest ranking five attributes among the importance of optical shop selection are "provide free gifts", "scale or size of an optical shop", "opening time and closing time", "convenient parking facilities", "favorable countenance of staff". The two highestr ranking criteria among the importance of optical shop information sources are "previous utilization experience", "recommendation by a relative, a friend and a family etc". The two lowest ranking criteria among the importance of optical shop information sources are "advertisement" and "spatial exterior view of optical shop". Conclusions: It is shown that the important thing in management of an optical shop is an inner caliber like ability of ophthalmic optician, interaction with customers, and previous utilization experience rather than external factors like advertisement, exterior view, and bonus gift.