• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.71-76
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• 2003

This study was performed to survey dioptric differences between the refractive states of both eyes from 1,100 patients who were given their prescriptions in spectacles. The differences were obtained by using dioptric power matrix. The prevalence of anisometropia was 96.9% for isoanisometropia, 2.9% for simple anisometropia, 0.2% for antimetropia. Spherical anisometropia was 22.1%, cylindrical anisometropia was 10.9%, spherocylindrical anisometropia was 46.5%, and no anisometropia was 20.5%. Anisometropia was more in thirties and forties than in other groups. In distribution of only spherical diopter differences, 76.1% were less than 0.50D, 91.7% were under 1.00D, only 2.5% were over 2.00D. In cylindrical diopter differences alone, 93.3% had under 0.50D, 1.7% had more than 1.00D. In spherocylindrical anisometropia, 52.8% were less than 0.50D, 78.6% were under 1.00D, 5.1% were more than 2.00D. In axis differences, with-the-rule type was 29.9%, against-the-rule type was 29.8%, oblique type was 40.3%.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.197-202
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• 2013

Purpose: This research was performed to measure and analyze scotopic pupil size in myopes and to figure out the factors that influence it. Methods: The pupil size of 191 healthy myopic subjects were measured with the pupillometer (Colvard pupillometer, OASIS medical, USA) in scotopic and analyzed with the age, corneal size, spherical equivalent refractive error, corneal curvature. In addition, it was compared with the measurements of intra-examiner and inter-examiner to verify reproducibility of pupillometer. Results: The mean (${\pm}$SD) scotopic pupil size was $6.64{\pm}0.68$ mm (range, 5.00~8.00 mm), the lower age and the larger corneal size, The bigger the pupil size. The lower spherical equivalent refractive error and steepper corneal curvature tends to be smaller. The reproducibility of intra-examiner and inter-examiner in pupillometer showed the reliability highly (Guttman splithalf point > 0.91). Conclusions: The pupil size associated with age, corneal size, spherical equivalent refractive error and corneal curvature in scotopic condition. It can refer to prevent inconvenience that may occur RGP contact lenses, cataract surgery and refractive surgery.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.435-440
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• 2016

The aim of study was to provide the preliminary data to find out characteristics of the difference between both refractive errors through analysis of ocular components variation. We measured spherical equivalent power and corneal radius with KR-8800, and axial length and anterior chamber depth with IOL Master, and the difference of measuring values between the right eye and left eye was applied as the absolute values in 100 adults aged 20~59 years. In all participants, the most common results showed that spherical equivalent power was $-1.83{\pm}2.17D$, axial length was 23.00~24.99mm, corneal radius was 7.50~7.89mm, and anterior chamber depth was 3.60~4.09mm. There are significant correlations between both eyes in axial length and anterior chamber depth with the difference of both spherical equivalent power. The difference of both axial lengths was the biggest with the difference of both refractive errors, and shown the highest correlation. The convergence complex study through classification by aspects is needed since the difference of both refractive errors is closely related with ocular components variation, and poor visual function would be caused by the difference of both refractive errors.

• Korean Journal of Optics and Photonics
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• v.28 no.4
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• pp.158-165
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• 2017

The physical shape of an ultrasound transducer has not been considered in previous studies of the photoacoustic saturation effect, where a photoacoustic signal's magnitude linearly increases as an absorption coefficient increases and it is finally saturated. In this paper, the effect of a spherically focused ultrasound transducer on photoacoustic nonlinearity is investigated. The focused ultrasound transducer's spatial filtering effect on photoacoustic signals is analytically derived considering the combined concept of a virtual point detector and Green function approach. The ultrasound transducer's temporal response (i.e., transfer function) effect on photoacoustic signals is considered by integrating photoacoustic signal values within the absorption area covered by a spatial resolution of the ultrasound transducer. Results from the analytically derived expression show that the magnitude of photoacoustic signals measured by a spherical focused ultrasound transducer shows a maximum at a specific absorption coefficient, and decreases after that maximum point as an absorption coefficient is increased. The origin of this photoacoustic nonlinearity is physically understood by comparing the ultrasound transducer's transfer functions and photoacoustic resonance spectra. In addition, this physical interpretation implies that the photoacoustic nonlinearity is strongly dependent on the irradiance distribution inside an absorption medium.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.423-427
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• 2005

In this paper, we propose easily tooling method for Seidel third order aberration, which are not well utilized in actual design process due to the complication of mathematical operation and the difficulty of understanding Seidel third order aberration theory, even though most insightful and systematic means in pre-designing for the initial data of optimization. First, using paraxial ray tracing and Seidel third order aberration theory, spherical aberration coefficient is derived for a two-mirror system with a finite object distance. The coefficient, which is expressed as a higher-order nonlinear equation, consists of design parameters(object distance, two curvatures, and inter-mirror distance) and effective focal length(EFL). Then, the expressed analytical equation is solved by using a computer with numerical analysis method. From the obtained numerical solutions satisfying the nearly zero coefficient condition($<10^{-6}$), linear fitting process offers a linear relationship called the curvature linear equation between two mirrors. Consequently, this linear equation has two worthy meanings: the equation gives a possibility to obtain initial design data for optimization easily. And the equation shows linear relationship to a two-mirror system with a finite object distance under the condition of corrected third order spherical aberration.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.29-36
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• 2006

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.80-81
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.109-110
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.31-32
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• 2008

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.160-165
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• 1998

A theoretical analysis has been undertaken to show the influence of bearing geometry on the steady state characteristics of air lubricated spherical tilting pad bearings. The geometry variations considered are the number of pads, the eccentricity ratio, the direction of load, and the preloading.