• Journal of the Ergonomics Society of Korea
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• v.34 no.1
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• pp.29-43
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• 2015

Objective: The aim of this study is to develop management guidelines and a procedure for an anthropometric suitability assessment of the main control room (MCR) in nuclear power plants (NPPs). Background: The condition of the MCR should be suitable for the work crews in NPPs. The suitability of the MCR depends closely on the anthropometric dimensions and ergonomic factors of the users. In particular, the MCR workspace design in NPPs is important due to the close relationship with operating crews and their work failures. Many documents and criteria have recommended that anthropometry dimensions and their studies are one of the foremost processes of the MCR design in NPPs. If these factors are not properly considered, users can feel burdened about their work and the human errors that might occur. Method: The procedure for the anthropometric suitability assessment consists of 5 phases: 1) selection of the anthropometric suitability evaluation dimensions, 2) establishment of a measurement method according to the evaluation dimensions, 3) establishment of criteria for suitability evaluation dimensions, 4) establishment of rating scale and improvement methods according to the evaluation dimensions, and 5) assessment of the final grade for evaluation dimensions. The management guidelines for an anthropometric suitability assessment were completed using 10 factors: 1) director, 2) subject, 3) evaluation period, 4) measurement method and criteria, 5) selection of equipment, 6) measurement and evaluation, 7) suitability evaluation, 8) data sharing, 9) data storage, and 10) management according to the suitability grade. Results: We propose a set of 17 anthropometric dimensions for the size, cognition/perception action/behavior, and their relationships with human errors regarding the MCR design variables through a case study. The 17 selected dimensions are height, sitting height, eye height from floor, eye height above seat, arm length, functional reach, extended functional reach, radius reach, visual field, peripheral perception, hyperopia/myopia/astigmatism, color blindness, auditory acuity, finger dexterity, hand function, body angle, and manual muscle test. We proposed criteria on these 17 anthropometric dimensions for a suitability evaluation and suggested an improvement method according to the evaluation dimensions. Conclusion: The results of this study can improve the human performance of the crew in an MCR. These management guidelines and a procedure for an anthropometric suitability assessment will be able to prevent human errors due to inadequate anthropometric dimensions. Application: The proposed set of anthropometric dimensions can be integrated into a managerial index for the anthropometric suitability of the operating crews for more careful countermeasures to human errors in NPPs.

• Korean Journal of Optics and Photonics
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• v.6 no.3
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• pp.188-200
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• 1995

A design of unit magnification 2-mirror system with high resolution is presented. It is for soft X-ray(wavelength of 13 nm) projection imaging and suitable for preparation of high density semiconductor chip. In general, a holosymmetric system with unit magnification has the advantage that both coma and distortion are completely eliminated. In our holosymmetric 2-mirror system, spherical aberration is addtionally removed by using two identical paraboloidal mirror surfaces and field curvature aberration is also corrected by balancing Petzval sum and astigmatism which depends on the distance between two mirrors, so that the system is a aplanatic flat-field paraboloidal 2-mirror holosymmetric system. This 2-mirror system is small in size, and has a simple configuration with rotational symmetry about optical axis, and has also small central obscuration. Residual finite aberrations, spot diagrams, and diffraction-based MTF's are analyzed for the check of performances as soft X-ray lithography projection system. As a result, the image sizes for the resolutions of$0.25\mum$and $0.18\mum$are 4.0 mm, 2.5 mm respectively, and depths of focus for those are $2.5\mum$, $2.4\mum$respectively. This system should be useful in the fabrication of 256 Mega DRAM or 1 Giga DRAM. DRAM.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.304-312
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• 2005

Field performance of several different types of diffractive optical elements(DOEs) has been carried out. Using Zemax model, we have designed five different types of DOEs, such as transmissive flat-DOE, transmissive curved-DOE, reflective flat-DOE, reflective curved-DOE and parabolic mirror, We have applied two different wavelengths, i.e., 13 m(EUV) and 632.8 nm(visible) to above DOEs. Off_axis dominate aberrations and the diffraction limiting (Rayleigh limit) field angles have been investigated and compared at both wavelengths for each DOE. At diffraction limit, field angle of curved-DOEs was much greater than that of flat-DOEs for both transmission and reflective types. We also showed that dominated off_axis aberration of flat-DOEs was coma, but that of curved-DOEs was mixture of astigmatism and curvature of field. The measured field angle and expected OPD aberrations were well coincided with theoretical ones. Increasing the ratio of field angle with wavelength was more effective in curved-DOEs than flat-DOEs.

• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.314-322
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• 2021

A reflecting telescope consists of a concave primary mirror and a convex secondary mirror. The primary mirror is easy to measure, because it converges the beam from an interferometer, while the secondary mirror diverges the beam and so is not easy to measure, even though it is smaller than the primary mirror. In addition, the Korsch-type telescope uses the central area of the secondary mirror, so that the entire area of the secondary mirror needs to be measured, which the classical Hindle test cannot do. In this paper, we propose a double-stitching method that combines two separate area measurements: the annular area, measured using the Hindle stitching method, and the central area, measured using a spherical wave from the interferometer. We test the surface error of a convex asphere that is 202 mm in diameter, with 499 mm for its radius of curvature and -4.613 for its conic constant. The surface error is calculated to be 19.5±1.3 nm rms, which is only 0.7 nm rms different from the commercial stitching interferometer, ASI. Also, the two results show a similar 45° astigmatism aberration. Therefore, our proposed method is found to be valuable for testing the whole area of a convex asphere.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.409-415
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• 2011

Purpose: To design applied anamorphic lens that focal length ratio is 3:1 optical system to improve detecting distance. Methods: We defined a boundary condition as $50^{\circ}{\sim}60^{\circ}$ for viewing angle, horizontal direction 36mm, vertical direction 12 mm for focal length, f-number 4, $15{\mu}m{\times}15{\mu}m$ for pixel size and limit resolution 25% in 33l p/mm. Si, ZnS and ZnSe as a materials were used and 4.8 ${\mu}m$, 4.2 ${\mu}m$, 3.7 ${\mu}m$ as a wavelength were set. optical performance with detection distance, narcissus and athermalization in designed camera were analyzed. Results: F-number 4, y direction 12 mm and x direction 36 mm for focal length of the thermal optical system were satisfied. Total length of the system was 76 mm so that an overall volume of the system was reduced. Astigmatism and spherical aberration was within ${\pm}$0.10 which was less than 2 pixel size. Distortion was within 10% so there was no matter to use as a thermal optical camera. MTF performance for the system was over 25% from 33l p/mm to full field so it was satisfied with the boundary condition. Designed optical system was able to detect up to 2.9 km and reduce a diffused image by decreasing a narcissus value from all surfaces except the 4th surface. From sensitivity analysis, MTF resolution was increased on changing temperature with the 5th lens which was assumed as compensation. Conclusions: Designed optical system which used anamorphic lens was satisfied with boundary condition. an increasing resolution with temperature, longer detecting distance and decreasing of narcissus were verified.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.211-221
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• 2004

The purpose of this study is to evaluate the distribution and change of curvature of the anterior corneal surface with age in emmetropia. 504 subjects who have emmetroia with good naked vision of at least 0.6-1.0 (spherical equivalent: +0.75D- -0.75D) participated in this study. The 504 subjects into 8 groups with 10 year interval from 3-year to 83-year, and their corneal curvatures were analyzed using manual keratometry. The results are as follows. In individual analysis: First, regression analysis of corneal curvature radius with age has given an equation: Y = -0.003x + 7.796 (r = -0.26). The average corneal curvature radii was measured to be $7.68{\pm}0.25mm$ at 38.3-year and range was 6.98-8.54 mm. Second, frequency of corneal curvature radius were obtained in 36% between 7.61 and 7.80 mm, 78% between 7.41 and 8.00 mm, 96% between 7.21 and 8.20 mm, 100% between 6.98 and 8.54 mm. Third, as for the comparison of corneal curvature radius with respect to sex, The mean value of male (n = 304, mean: 37.6-year $7.72{\pm}0.24mm$, Range: 7.09-8.54 mm) is larger than that of female (n = 200, mean: 39.3-year $7.62{\pm}0.24mm$, Range: 6.98-8.42 mm) by 0.1mm (p<0.01). In groups analysis: First, regression analysis of corneal curvature radius with age has given an equation: $Y=-0.0066x^2+0.0227x+7.7282$ (r = -0.90). Second, vertical and horizontal curvature radius decreased with age (p < 0.01). Especially the decrease of horizontal curvature radius were more pronounced than the decrease of vertical (horizontal:10-70 age group: 0.38 mm decrease, vertical:10-70 age group: 0.20 mm decrease). Third, difference between steep and flat meridian (astigmatism) progressively decreased with age. (low age group:0.18 mm difference, high age group: 0.08 mm difference). Fourth, the corneal curvature radius of male was larger than female's in total groups(p < 0.01). Consequently, the change of corneal curvature radius with age progressively decreased in all conditions (mean, vertical, horizontal, male, and female) and this change was more outstanding in horizontal rather than in vertical.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.2
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• pp.91-98
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• 2016

Purpose: This study investigated the masking effect of the hydrogel lens and silicone hydrogel lens on the cornea with refractive surgery and without surgery. Methods: 24 university students (means age: $23.48{\pm}2.89years$) without refractive surgery (12, control group) and with refractive surgery (LASIK: 8, LASEK: 4, experimental group) participated in the study. Mean refractive errors of right eyes were -2.73 D for control group and -0.24 D for experimental group. The differences in the refractive power and corneal topography map between pre- and post-wearing the -3.00 D lenses were compared, and 2 kinds of hydrogel contact lenses (0.89 Mpa, 0.49 Mpa) and 2 kinds of silicone hydrogel lenses (1.5 Mpa, 0.8 Mpa) were used for -3.00 D lenses. NVision-K5001 (Shin nippon, Japan) was used to measure the refractive power and Keratograph 5M (Oculus, Germany) to measure the corneal topography map change. Results: Variations in the refractive power increased to the plus direction in the experimental group after wearing soft contact lenses. The corneal topography map showed significant changes on the both groups after wearing soft contact lenses (p<0.05). However there were no significant differences in the refractive power and corneal topography map variations by lens materials. Conclusions: Wearing soft contact lenses showed corneal topography map changes. Especially wearing soft contact lenses on the flat cornea after corneal refractive surgery showed greater corneal power changes. Therefore, it should pay attention to refractive change in case of prescribing soft contact lenses to patients with corneal refractive surgery.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.551-555
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• 2014

Purpose: This study is to investigate if the improvement of visual sensory (VS) by amblyopia treatment affects the ocular functions in refractive errors, accommodative errors and phoria at distance and near. Methods: 10 subjects (17 eyes, mean age of $10.7{\pm}2.9$ years) who treated amblyopia completely, were participated for this study. Refractive errors, accommodative errors, and distance and near phoria were compared between before and after treatments of amblyopia. Refractive errors and accommodative errors at 40 cm were measured using openfield auto-refractor (NVision-5001, Shin Nippon, Japan) and using monocular estimated method (MEM) respectively. Phoria was determined at 3 m for distance and at 40 cm for near using Howell phoria card, cover test or Maddox rod. Results: Mean corrected visual acuity (CVA) significantly increased from $0.46{\pm}0.11$ (decimal notation) for before amblyopia treatment to a level of $1.03{\pm}0.13$ for after amblyopia treatment (p < 0.001). For spherical refractive error, hyperopia significantly decreased from $+2.29{\pm}0.86D$ to a level of $+1.1{\pm}2.38D$ (p < 0.05) but astigmatism did not significantly change; $-1.80{\pm}1.41D$ for before treatment and $-1.65{\pm}1.30D$D for after treatment (p > 0.05). Accommodative error significantly decreased from accommodative lag of $+1.1{\pm}0.75D$ to a level of $+0.5{\pm}0.59D$ (accommodative lag) (p < 0.05). Distance phoria significantly changed from eso $2.9{\pm}6.17PD$ (prism diopters) to a level of eso $0.2{\pm}3.49PD$ (p < 0.05), and near phoria also significantly changed from eso $0.4{\pm}2.32PD$ to level of exo $2{\pm}4.9PD$ (p < 0.05). There was a high correlation (r = 0.88, p < 0.001) between improvement of visual acuity and decrease of accommodative lag. Conclusions: Hyperopic refractive error decreased with improvement of CVA or VS by amblyopia treatment. And the improvement of VS by amblyopia treatment also improved accommodative error, and changed phoria coupled with accommodation.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.273-281
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• 2011

Purpose: In order to provide the fundamental information for the design development of RGP lenses and its clinical prescription, the corneal types of Korean twenties were analyzed according to corneal shapes, astigmatic degree, and the certain distance from the corneal apex. Methods: Corneal types of total 252 eyes in 20s were firstly classified, then their corneal radii from the certain distance from the corneal apex were measured by corneal topography and further analyzed based on the astigmatic degree. Results: Korean 20s' corneal types were classified as 14.3%(36 eyes) of round, 31.3%(79 eyes) of oval, 28.6%(72 eyes) of symmetric bow tie, 17.5%(44 eyes) of asymmetric bow tie, 8.3%(21 eyes) of irregular shapes. The round and oval typed corneas had mild astigmatic degree whereas the higher astigmatic degree in symmetric and asymmetric bow tie typed corneas were shown. The relative corneal radii of round and oval typed corneas at each distance from corneal apex were shown to consistently increase regardless of astigmatic degrees when they measured at certain distances from the corneal apex. However, the relative corneal radii of symmetric and asymmetric bow tie typed corneas within 1.0-1.5mm from the corneal apex were decreased, which showed steeper slope than it within 1.0 mm and somewhat different based on astigmatic degrees. Bigger change of corneal radii outer 3.5 mm from the corneal apex in symmetric bow tie typed corneas with astigmatism of 1.50-2.00 D and 2.25-2.75 D appeared. Conclusions: The consideration of radial change from the central cornea to peripheral cornea is necessary for manufacturing RGP lens and its prescription since they showed different change in corneal radii by corneal patterns and astigmatic degrees.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.265-272
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• 2011

Purpose: The clinical usefulness of rotation evaluation using objective refraction in toric soft lenses fitting was investigated. Methods: Toric soft lenses were fitted for 32 subjects (64 eyes; mean age of 24.69 ${\pm}$ 1.65 years) with astigmatism and both eyes of each subject were fitted with toric soft lenses. Objective refraction-based lenses rotation was evaluated from refraction and over-refraction data by indirect calculating technique. These calculated data were compared with the measured data from slit lamp with direct measuring technique. Results: Orientation of toric soft lenses around zero position (within ${\pm}$ 5$^{\circ}$ vertical line) was investigated. The orientations to the direction of nose of measured and calculated values were 69.78% and 63.64%, respectively, which showed similar values between two techniques. Agreement frequency between measured and calculated values in the magnitude of lenses rotation 54.69% and 82.82% for 10$^{\circ}$ and 20$^{\circ}$ of vertical line, respectively. The 95% limits of agreement between calculation and measurement were from -10.08$^{\circ}$ to 12.65$^{\circ}$, and mean difference was 1.29$^{\circ}$ within ${\pm}$ 10$^{\circ}$. The result showed there was no significant difference (p = 0.1984) and high correlation (r = 0.56, p = 0.0004) between two techniques. But the 95% limits of agreement was widen in ${\pm}$ 20$^{\circ}$ of vertical line. The magnitude of lens rotation between two methods was 9.66 ${\pm}$ 6.16$^{\circ}$, 16.17 ${\pm}$ 12.38$^{\circ}$ and 10.58 ${\pm}$ 12.02$^{\circ}$ for normal, loose and tight fitted conditions. Conclusions: From the results with smaller difference between two techniques, it was found that higher availability of subjective over-refraction data can be used as a supplementary tool for subjective refraction. An application using objective refraction with direct measuring could be provide high success in prescription on toric soft lenses.