• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.2
• /
• pp.187-193
• /
• 2011

Purpose: This study was to compare differences between both eyes in corneal powers, axial lengths, anterior chamber depths in anisometropia and isometropia, and to investigate the relationship between anisometropia and refractive components. Methods: The subject was a total of 83 patients, anisometropia 45 patients (90 eyes) and isometropia 38 patients (76 eyes) from 2.7 to 15.3 years old, prescribed eyeglasses and contact lenses by refraction from July 2010 to August 2010 in Gwangju City B eye clinic. Axial length, anterior chamber depth, corneal curvature, and corneal refractive power were measured using IOL Master. Refractive error was measured using an Auto-refractometer. Results: Anisometropia was a statistically significant difference in axial length, binocular refractive components, refractive error, and axial length, Axial length/corneal radius (AL/CR) ratio showed a statistically significant difference in anisometropia and isometropia. The major cause of anisometropia all 45 subjects was the axial length. Among the refractive components axial length, AL/CR had a strong correlation, but corneal refractive power had no correlation. Anterior chamber depth had a weak correlation. Conclusions: This study found that refractive error was the most axial ametropia caused by the axial length. The main cause of anisometropia was the axial length, but refractive components had a weak correlation.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.34 no.1
• /
• pp.78-86
• /
• 1992

This paper aims at investigating the effect of steel ratio and the magnitude of edge-ratio on the mechanical characteristics of reinforced concrete ring sector plate. The influence of steel bars was taken into account by coupling stiffness matrix of the steel bar element with that of the concrete plate element without dealing with separate element of steel bar and by establishing the composite stiffness matrix, which leads to the desirable result which does not increase th number of element could be obtained. Through case studies with 6 cases various steel ratios in ring sector plate supported at four edges and 4 cases with different open angles, the influence of the steel ratio was examined. A numerical analysis to find out the effect of the steel ratio d ue to above mentioned cases was carried out by 4 boundary conditions ; all edges clamped (B.C-1), all edges simply supported (B.C-2), curvilinear two edges clamped and other edges free (B.C-3) and curvilinear two edges simply supported and other edges free(B.C-4). The main results obtained are summarized as follows : 1. The effect of steel ratio on the magnitude of lateral deflection and x-directional bending moment at the center of sector plate and the midpoint of outer and inner curvilinear edges is almost the same up to $30^{\circ}$ of open angle. Beyond $30^{\circ}$ of the angle, the larger the angle, the greater the effect of ratio. 2. In design works using balanced steel ratio, the effect of steel bar can be ignored. But for larger open angles, especially greater than $90^{\circ}$, it proves desirable to consider the effect of steel bar. 3. The effect of the arc length of center circle/straight edge on lateral deflection and bending moment is remarkable in B.C-2. For larger open angle, the effect is also noted except for B.C-3 which turn out hardly affected. 4. The effect of the radius of curvature/straight side length on lateral deflection and x-directional bending moment is noted in B.C-2. As open angle increases, B.C-1 and B.C-3 almost agree and B.C-2 approaches B.C-4.

• Nuclear Engineering and Technology
• /
• v.56 no.5
• /
• pp.1619-1626
• /
• 2024

In order to optimize the operational safety and reliability of the upper launcher for the CFETR ECRH system, a design of the launcher for NTM control based on the remote steering concept is currently being carried out for comparison with the front steering equivalent. This paper presents the layout design and analysis of the quasi-optical system in the remote steering launcher. A 3D visual quasi-optical design tool has been developed for the quasi-optical system, which can parameterize modeling, perform general astigmatic beam calculation and show the accurate beam propagation path in the upper port. Three identical sets of quasi-optical modules are arranged in the launcher, and each one consists of two fixed double-curvature focusing mirrors, which focus and reflect the steering beams (- 12°-12°) from two square corrugated waveguides. The beam characteristics at the resonance layer are described, and the average beam radius is < 100 mm. The peak head loads on the surfaces of the two fixed mirrors are 1.63 MW/m² and 1.52 MW/m². The position and size of the beam channel in the blanket are obtained, and the opening apertures on the launcher-facing and plasma-facing sides of the blanket module are 0.54 m² and 0.4 m², respectively.

• Journal of Biomedical Engineering Research
• /
• v.28 no.2
• /
• pp.218-228
• /
• 2007

Modem concepts of gait rehabilitation after stroke favor a task-specific repetitive approach. In practice, the required physical effort of the therapists limits the realization of this approach. Therefore, a mechanized gait trainer enabling nonambulatory patients to have the repetitive practice of a gait-like movement without overstraining therapists was constructed. In this study, we developed an active gait training system for patients with gait disorder. This system provides joint movements to patients who cannot carry out an independent gait. It provides a normal stance-swing ratio of 60:40 using an eccentric configuration of two gears. Joint motions of the knee and the ankle were evaluated with using the 3D motion analysis system and compared with the results from the multi-body dynamics simulation. In addition, clinical investigations were also performed for low stroke patients during the 6-week gait training. Results from the dynamics simulation showed that joint movements of the knee and the ankle were affected by the gear size, the step length and the length of the foot plate, except the radius of curvature of the foot guide plate. Also, the 6-week gait training revealed relevant improvements of the gait ability in all low subjects. Functional ambulation category levels of subjects after training were 2 in three patients and 1 in a patient. The developed active gait trainer seems feasible as an adjunctive tool in gait rehabilitation after stroke.

• Fashion & Textile Research Journal
• /
• v.20 no.4
• /
• pp.429-438
• /
• 2018

This study analyzed the fit-zone of the neck for females in their 60s. We considered the standard body types of females in their 60s and the four body types from the sixth Size Korea. The results of the study were as follows. We could not determine a pattern formula for the neck based on the changes in the body type of females in their 60s. However, the position of the lateral neck point generally showed a significant difference from that of females in their 20s. In the case of the shoulder angle, the point of the shoulder was angled slightly towards the back in all body types. It was also found that the curve of the neck circumference for both the collar and the bodice should have been smoother than what was shown on the 3D shape. The larger the height difference between the point of the back of the neck and the lateral neck point in the 3D shape, the smoother the design should be at the curve of the circumference at the front of the neck. A larger curvature in the front radius of the 3D shape increased the difference in the shape of the curve between the collar and the basic pattern of the bodice. Hence, a more careful design is required for these parts of the pattern. In addition, the more the front neck is bent, the smoother the circumference curve should be in the pattern design at the front of the neck and the collar.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.150-150
• /
• 2010

Carbon nanotubes have drawn attention as one of the most promising emitter materials ever known not only due to their nanometer-scale radius of curvature at tip and extremely high aspect ratios but also due to their strong mechanical strength, excellent thermal conductivity, good chemical stability, etc. Some applications of CNTs as emitters, such as X-ray tubes and microwave amplifiers, require high current emission over a small emitter area. The field emission for high current density often damages CNT emitters by Joule heating, field evaporation, or electrostatic interaction. In order to endure the high current density emission, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects: highly crystalline CNT materials, low gas emission during electron emission in vacuum, optimal emitter distribution density, optimal aspect ratio of emitters, uniform emitter height, strong emitter adhesion onto a substrate, etc. We attempted a novel approach to fabricate CNT emitters to meet some of requirements described above, including highly crystalline CNT materials, low gas emission, and strong emitter adhesion. In this study, CNT emitters were fabricated by filtrating an aqueous suspension of highly crystalline thin multiwalled CNTs (Hanwha Nanotech Inc.) through a metal mesh. The metal mesh served as a support and fixture frame of CNT emitters. When 5 ml of the CNT suspension was engaged in filtration through a 400 mesh, the CNT layers were formed to be as thick as the mesh at the mesh openings. The CNT emitter sample of $1{\times}1\;cm^2$ in size was characteristic of the turn-on electrical field of 2.7 V/${\mu}m$ and the current density of 14.5 mA at 5.8 V/${\mu}m$ without noticeable deterioration of emitters. This study seems to provide a novel fabrication route to simply produce small-size CNT emitters for high current emission with reliability.

• Design & Manufacturing
• /
• v.17 no.3
• /
• pp.8-14
• /
• 2023

In this study, basic research was conducted on manufacturing technology of thick-walled light guide a component that controls the light source of automobile lamps. As a preliminary study for manufacturing the final injection molded parts, a model for analyzing the influence of micro patterns on light guides is presented. The optical characteristics of the light guide were analyzed according to the change of the curvature radius of the micro-optical pattern, and the injection molding characteristics of the light guide according to the change of injection molding conditions were analytically evaluated. It was confirmed that the luminance uniformity improves as the R value decreases for changes in the micro-pattern R value, but it was confirmed that there are technical limitations in actual injection mold core processing and high-replication injection molding. Injection molding analysis showed that cooling channel design is very important compared to general injection molding due to thick-wall characteristics and thickness variation. It was also confirmed that the cooling channel has a great influence on the cycle time and birefringence result due to residual stress. As a result of analyzing the influence of filling time, holding condition, and cooling on shrinkage, it was found that the cooling water temperature has a significant effect on the shrinkage of ultra-fine light guide parts, and the holding condition also has a significant effect.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.3
• /
• pp.324-330
• /
• 2013

This paper describes a novel method to surface large optics mirror with an extremely high hardness, which could replace the high cost of the repetitive off-line measurement steps and the large ultra-precision grinding machine with ultra-positioning control of 10 nm resolution. A lot of diamond pellet to be attached on the convex aluminum base consists of a grinding tool for the concave large mirror, and the tool was pressured down on the large mirror blank. The tool motion at an interval on the spiral path was controlled with each feed rate as the dwell time in the conventional computer-controlled polishing. The shape to be surfaced was measured directly by a touch probe on the machine without any separation of the mirror blank. Total 40 iterative steps of the surfacing and measurement could demonstrate the form error of RMS $7.8{\mu}m$, surface roughness of Ra $0.2{\mu}m$ for the mirror blank with diameter of 1 m and spherical radius of curvature of 5400 mm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.5
• /
• pp.367-372
• /
• 2013

In this paper, micro dried bio-potential electrodes are demonstrated for sEMG (surface ElectroMyoGraphic) signal measurement using conductive epoxy on the textile fabric. Micro dried bio-potential electrodes on the textile fabric substrate have several advantages over the conventional wet/dry electrodes such as good feeling of wearing, possibility of extended-wearing due to the good ventilation. Also these electrodes on the textile fabric can easily apply to the curved skin surface. These electrodes are fabricated by the screen-printing process with the size of $1mm{\times}10mm$ and the resultant resistance of these electrodes have the average value of $0.4{\Omega}$. The conventional silver chloride electrode shows the average value of $0.3{\Omega}$. However, the electrode on the textile fabric are able to measure the sEMG signal without feeling of difference and this electrode shows the lower resistance of $1.03{\Omega}$ than conventional silver chloride electrode with $2.8{\Omega}$ in the condition of the very sharp curve surface (the radius of curvature is 40 mm).

• Proceedings of the KOSOMBE Conference
• /
• v.1993 no.05
• /
• pp.57-60
• /
• 1993

A finite element-based computer simulation of excimer laser susery was conducted to study some factors on the surgery. In particular, the radius of curvature at the apex of the cornea was examined under various surgical conditions. Corneal tissue was assumed to be a nearly incompressible, linear elastic, homogeneous, isotropic material under very small deformation. The geometry of the human cornea was taken from the experimental data[1]. The simulation utilized ANSYS(Swanson Analysis System Inc.Rev.4.4A). In this study, the major factors which affect the outcomes of the excimer laser surgery were investigated. First, two patterns of surgery with various surgery thickness(40-70micrometers) were examind. The pattern#1 describes the meridian from the apex to the edge of the surgery area to be straight. And the corresponding meridian of the pattern 2 can be expressed as a quardratic function. The results show that the pattern #2 is more realistic and effective. Then, the effects of other factors were investigated based on the pattern #2. Other factors are:various diameters of the surgical area (3-8 milimeters), Young's modules(3.5-4.5MPa), and depth of surgery at the apex(40-70micrometers). Compared with the computer simulation of the radial keratotomy surgery[2], the excimer laser surgery was proven to be more effective in treating myopia patients. In conculusion, the results of the simulation are qualitative agreement with clinical experience[3] indicating the potential of the finite element model of the surgery as a guideline to the surgeon before actual surgery.