• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.401-409
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• 2007

A new sheet of back light unit(BLU) to reduce the number of sheets and enhance the optical performances of direct back light unit(BLU) in a liquid crystal display is proposed and designed. In order to improve the straightness and spatial uniformity of brightness of the BLU, we design the new sheet with linear arrays of complicated bar prism by using the fusion of cylindrical lens and bar prism. Then, we investigate and analyze various optical performances of a BLU including the new sheet through an illumination optical system design program. From these results, we determine the optimum geometrical structure of the sheet. Under the optimum condition, the luminance efficiency and spatial uniformity of luminance of the BLU are 53.5% and 83.5% respectively. And the vertical and horizontal widths of the angular luminance distribution are $90^{\circ}$ and $112.5^{\circ}$ respectively. Finally we have fabricated a new BLU sheet according to this design shape by using an ordinary resins.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.109-114
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• 2006

We evaluated the contour using corneal asphericity of the myopic cornea in Korea and investigated the relationship between refractive error and other ocular dimensions in Korean myopia, including anterior chamber depth and asphericity. The monoocular asphericity value of 50 myopes with $-4.83{\pm}2.38$ D between early 20 age and early 30 age in adult was included. Cycloplegic refraction, corneal asphericity and anterior chamber depth using corneal topography were examined. The mean asphericity values were$-0.27{\pm}0.13$ and the corneas of 96.0% were prolate ellipse. Refractive error was related to asphericity and anterior chamber depth among myopes. However, asphericity only were significant difference in high and low myopia group. Corneal configuration on the contact lens fits are discussed. We think that the longitudinal study for myopia and asphericity was required.

• Parasites, Hosts and Diseases
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• v.46 no.3
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• pp.157-164
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• 2008

Three Acanthamoeba isolates (KA/E9, KA/E17, and KA/E23) from patients with keratitis were identified as Acanthamoeba triangularis by analysis of their molecular characteristics, a species not previously recognized to be a corneal pathogen. Epidemiologic significance of A. triangularis as a keratopathogen in Korea has been discussed. Morphologic features of Acanthamoeba cysts were examined under a microscope with differential interference contrast (DIC) optics. Mitochondrial DNA (mtDNA) of the ocular isolates KA/E9, KA/E17, and KA/E23 were digested with restriction enzymes, and the restriction patterns were compared with those of reference strains. Complete nuclear 188 and mitochondrial (mt) 16S rDNA sequences were subjected to phylogenetic analysis and species identification. mtDNA RFLP of 3 isolates showed very similar patterns to those of SH621, the type strain of A. triangularis. 16S and 18S rDNA sequence analysis confirmed 3 isolates to be A. triangularis. 18S rDNA sequence differences of the isolates were 1.3% to 1.6% and those of 16S rDNA, 0.4% to 0.9% from A. triangularis SH621. To the best of our knowledge, this is the first report, confirmed by 18S and 16S rDNA sequence analysis, of keratitis caused by A. triangularis of which the type strain was isolated from human feces. Six isolates of A. triangularis had been reported from contaminated contact lens cases in southeastern Korea.

• Journal of the Optical Society of Korea
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• v.17 no.4
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• pp.344-349
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• 2013

This paper proposes a simulation algorithm to assess the gradual yellowing vision of the elderly, which refers to the predominance of yellowness in their vision due to aging of the ocular optic media. This algorithm employed the spectral transmittance property of a yellow filter to represent the color appearance perceived by elderly people with yellow vision, and modeled the changes in the color space through a spectrum change in light using the yellow filter effect. The spectral reflectivity data of 1269 Munsell matte color chips were used as reference data. Under the standard conditions of a D65 illuminant and a $10^{\circ}$ observer of 1964 CIE, the spectrum of the 1269 Munsell colors were processed through the yellow filter effect to simulate yellow vision. Various degrees of yellow vision were modeled according to the transmittance percentage of the yellow filter. The color differences before and after the yellow filter effect were calculated using the DE2000 formula, and the color pairs were selected based on the color difference function. These color pairs are distinguishable through normal vision, but the color difference diminishes as the degree of yellow vision increases. Assuming 80% of yellow vision effect, 17 color pairs out of $(1269{\times}1268)/2$ pairs were selected, and for the 90% of yellow vision effect, only 3 color pairs were selected. The result of this study can be utilized for the diagnosis system of gradual yellow vision, making various types of test charts with selected color pairs.

• Journal of Korean Clinical Health Science
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• v.11 no.1
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• pp.1639-1643
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• 2023

Purpose. We wanted to find out how the changes in brain function affected by the beats per minute (BPM) of music affected visual function. Methods. The subjects were 40 people in their 20s (30 men, 10 women) with no eye disease, strabismus, amblyopia and a corrected visual acuity of 1.0 or higher. Wearing headphones while excluding surrounding noise as much as possible, we played music while adjusting the beat rate at 40 BPM intervals from 80 to 200 BPM. Then, pupil size measurement, lag of accommodation test, and minus lens addition method maximum accommodation test were performed and analyzed. Results. As a result of analyzing changes in visual function according to beats per minute [BPM], it was found that although sound can be consciously affected, it does not directly affect visual function significantly in terms of accommodative lag and changes in pupil size. It was confirmed that the effect was limited to the maximum accommodation. Conclusions. In clinical practice, it is necessary to conduct a refraction test while keeping in mind that there are changes in visual function depending on the BPM of surrounding sounds.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.523-530
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• 2018

Purpose : The purpose of this study was to investigate the difference in the dynamic visual acuity between (DVA) the distance and near and the effect of change of accommodative stimulus on the dynamic visual acuity by the addition of the plus lens. Methods : The study involved 40 male and female adults ($22.84{\pm}2.43$ years old) with over 1.0 of visual acuity and without systemic disease or ocular disease. We compared the distance and near DVA and the change of DVA induced by the addition of the plus lens(+0.50D, +1.00D, +1.50D). Results : The distance DVA and near DVA are $78.86{\pm}19.46deg/sec$ and $76.90{\pm}18.05deg/sec$ respectively. The distance DVA was slightly higher(p=0.04). The higher the distance DVA, the higher the positive correlation with the near DVA and distance DVA, and distance DVA was higher in those who had higher the near DVA(r=0.95, p=0.00, Fig. 4). The near DVA according to the change of accommodative stimulus was $75.95{\pm}18.85deg/sec$ in full correction and the near DVA with +0.50D spherical power was $76.95{\pm}16.45$ but there was no statistically significant differences(p>0.05). However, the near DVA with +1.00D spherical power was $79.02{\pm}13.51deg/sec$ and it was slightly higher. Also, the near DVA with +1.50D spherical power was $84.28{\pm}18.96deg/sec$, there and it was statistically significant difference(p<0.05). Conclusion : There is no difference between distance and near DVA, but near DVA is also excellent if distance DVA is good. The DVA increases as added a plus lens for controlled accommodative stimulation changes.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.513-518
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• 2014

Purpose: This study was to investigate color distortion by colors and luminous transmittance of lenses with word-color test included in computerized neurocognitive function test (CNT). Methods: 32 subjects aged $21.97{\pm}1.58$ years with no ocular disease and color vision deficiency were selected. Four colors of tinted lenses, which were red, green and blue included in the primary colors of light and pink, and word-color test in CNT to evaluate changes in cognitive function by color distortion were used. Results: Response time was not significantly increased in green, blue, and pink among four colors, but significantly increased in only red color. And response time was significantly increased below 46% of luminous transmittance in red color. Conclusions: It should be cautious and careful of the red-tinted lens choice because red color with below 46% of luminous transmittance can distort colors of objects, and it could be related to safety problem. It is suggested that word-color test could be extensively used for further studies on color recognition.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.163-169
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• 2014

Purpose: This study is for compared the change of corneal refractive power before and after wearing of rigid gas permeable contact lense with diagnostic method which is 1 D flatter than alignment fitting on right eye and alignment fitting on left eye for 2 months and investigate the preference. Methods: Twenty middle school and high school students (40 eyes) who had never worn a contact lense before for no corneal topographical change, no ocular disease, no experience of ophthalmic surgery and have normal tear amount were selected for this study and corneal refractive power were examined before wearing rigid gas permeable contact lense and adaptation status and corneal examination were performed after 10 days of wearing and after cheking up the continuation of wearing, all candidate wear contact lens 8 hours per day for 2 month and corneal refractive power were compared. Results: After 2 months of wearing with 1 D flatter than the alignment fitting on right eyes, there was significant difference in the central corneal refractive power was $43.84{\pm}1.33D$, flat K power was $43.05{\pm}1.29D$, and steep K power was $44.61{\pm}1.42D$ decreased than before wearing (p<0.001, 0.001, 0.047). The e-value of the principal meridians also shows statistically significant difference (p=0.037, 0.015). After 2 months of wearing with alignment fitting on left eyes, the central corneal refractive power was $44.40{\pm}1.26D$, flat K power was $43.57{\pm}1.23D$. and flat K e-value was $0.58{\pm}0.05$ which showed no statistically significant difference (p = 0.769, 0.614, 0.181). But steep K power was $45.25{\pm}1.36$, and steep K e-value was $0.45{\pm}0.18$ which shows statistically significant difference (p=0.018, 0.027). Conclusions: Consider the comfort, clear vision, dryness for preference fitting investment, 6 students (30%) prefer right eye which is 1 D flatter fitting, 14 students (70%) prefer left eye which is alignment fitting. For rigid gas permeable fitting needed for accurate examination and should prescribe the alignment fitting which is suitable for each cornea.