• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.145-148
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• 2001

SiC composites were developed by incorporating glass phase into SiC, in the light of improving mechanical properties of material for spectacle lens cutting. Specimens for spectacle lens cutting with glass phase as sintering additives have been fabricated by hot-pressing at $1810^{\circ}C$ for 2 hr under a pressure of 25 MPa. The fracture toughness and hardness of hot-pressed specimens were characterized and compared with previous works. Typical hardness and fracture toughness of materials for spectacle lens cutting were 12 GPa and $5.1MPa{\cdot}m^{1/2}$ respectively.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.55-62
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• 2005

This paper presents mainly a procedure to get the mathematical form of the manufactured aspherical lens. Generally Schulz formula describes the aspherical lens profile. Therefore, the base curvature, conic constant. and high-order polynomial coefficient should be set to get the approximated design equation. To find the best-approximated aspherical form, lens profile is measured by a commercial stylus profiler, which has a sub-micrometer measurement resolution. The optimization tool is based on the minimization of the root mean square of error sum to get the estimated aspherical surface equation from the scanned aspherical profile. Error minimization step uses the Nelder-Mead simplex (direct search) method. The result of the lens refractive power measurement shows the experimental consistency with the curvature distribution of the best-approximated aspherical surface equation

• Korean Journal of Materials Research
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• v.31 no.8
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• pp.427-432
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• 2021

This study uses silicone monomer, DMA, crosslinking agent EGDMA, and initiator AIBN as a basic combination to prepare hydrogel lenses using fluorine-based perfluoro polyether and iron oxide and zinc oxide nanoparticles as additives. After manufacturing the lens using iron oxide nanoparticles and zinc oxide nanoparticles, the optical, physical properties, and polymerization stability are evaluated to investigate the possibility of application as a functional hydrogel lens material. As a result of this experiment, it is found that the addition of the wetting material containing fluorine changes the surface energy of the produced hydrogel lens, thereby improving the wettability. Also, the addition of iron oxide and zinc oxide nanoparticles satisfies the basic hydrogel ophthalmic lens properties and slightly increases the UV blocking performance; it also increases the tensile strength by improving the durability of the hydrogel lens. The polymerization stability of the nanoparticles evaluated through the eluate test is found to be excellent. Therefore, it is judged that these materials can be used in various conditions as high functional hydrogel lens material.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.2
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• pp.151-157
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• 2005

The purpose of this study is to get related appropriate data for correct awareness and education of the university students who are using contact lens by investigating university students' awareness, present status, using habits and complication of contact lens. The method of survey was made by questionnaires which were spread to the group of 408 university students. The result indicated some characteristics including using daily wear soft lens of 55.7%, the major motive of using them is for cosmetics of 45.6%. Among them, 54.9% experienced complication, and the xerophthalmia was the most conspicuous case in the aspect of the kinds of the complication. In the aspect of the place where they purchased the contact lens, 93% of the users bought them at eye glasses stores. But when they experienced inconveniences of the contact lens, only 18.8% consulted the Stores. In the fact, I think, the users don't seem to trust the stores fully. Furthermore, 43.5% endure the inconveniences when they get them without any treatment. The fact indicates that they don't realize the seriousness of the complication due to contact lens. Reviewing above-stated facts, information and education for correct awareness and managing methods of contact lens, the complication seem 10 be required. In addition, optician specialized knowledge on contact lens and the sense of duty on national eye health improvement seem to be required.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.129-134
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• 2002

We obtained the UV cut-off effect of tinted CR-39 Ophthalmic lens with the respect of concentration of green, brown, blue color. First, we analyzed the UV spectrum of tinted CR-39 lens measured by Spectrophotometer and then compared the UV data by Spectrophotometer with UV data by UV tester used in an optician shop. The result obtained show that the UV cut-off effect is increased with color concentration of tinted CR-39 lens, and the transmittance of 0%~5% at 400nm by Spectrophotometer is correspondence with transmittance of 0% by UV tester.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.59-64
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• 2003

To Photochoromic lens light irradiation side darkening status and fading status photo-transmittance decrease. If remove light irradiation, get into fading state and photo-transmittance has reversibility process that get back originally in state. Get CIE $L^*a^*b^*$ relationship colorimetric using darkening in Photochoromic lens and at fading process. Photochromism's spectrophotometer that produce itself. Darkening and fading state colorimetric ($a^*-b^*$) linear be curvy, and is gradidnt of (-) value. And change lineally. The colorimetric transfer amount is Blue ${\rightarrow}$ Yellow, Red ${\rightarrow}$ Green form. Colorimetric is low $b^*$ value than darkning state in fading state, and Photochromism's coodination transfer moves on the contrary with darkning state, photochoromism relationship estimation method about photochoromic lens can use by colorimetric difference about darkening and fading.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.169-174
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• 2002

Make Photochromic lens Photochromism estimation method, and gouge photochromic lens and investigated UV light source to apply. UV light source irradiation ago and after wavelength dependence of photo-transmittance (T%) of darkening and fading state by do optical equipment which is consisted of spectrophotometer, light source, power meter and detecter. Use relative ratio value of maximum $T%{\times}{\lambda}$ area and saturated state area in light off. Dependences estimation introduced darkening efficiency $(K_d)=(1-C_1/A_1)/t_{on}$ relationship value course fading efficiency$(K_f)=(C_2/A_2)/t_{on}$ value during Photochromism's irradiation time in Photochromic lens. Wavelength dependence of transmittance (T%) has form of $T_m+T_1{\exp}[-(x_0-t)/a]$ in Darkening course fading state. Can receive each estimation parameter value as result that apply Photochromism's estimation parameter Z, $K_d$, $K_f$ in Photochromic lens.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.301-312
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• 2004

This study was performed to compare the relationship between contact lens wearer and dry-eye patient. In this study, TBUT, SIT, TTT, Rose bengal staining and McMonnies dry eye symptom questionnaire were performed as a baseline. With the base data, the subjects were classified to 3 groups : 3S patients who have dry eye signs and symptoms, 38 patients who are wearing soft contact tenses, 35 subjects who have health eyes and never worn on a contact lenses as control subjects. Contact lens wearers were divided into 3 groups according to the duration of contact lens wear. There were no significant differences in TBUT, STT, TTT, Rose-bengal staining and McMonnies dry eye symptom questionnaire result between contact lens wearer group and dry eye patients group. We suggest that there are similarities in tear function tests between the dry-eye patient and the contact lens wearer.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.1-9
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• 2001

This research chose the existing designed copier zoom lens system and analyzed to calculate the optical capacity. As this lens system was the zoom lens system of finite object point, differed form the general camera zoom lens of infinite object point, it got a limited movement range because it moved between the fixed object and the image. In the result of comparison the optical capacities between a symmetric form and a asymmetric form. We could find out the truth which a asymmetric form constituted comparative stable aberrations and existed a tracks of effort for aberration correction. Therefore, a symmetric form is allotted satisfactorily from improved aberrations by itself in the fixed focal lens system. However, it has a limit of improving for capacity when it is used a zoom lens system got a symmetric form.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.263-267
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• 1998

Today's diopter of optical lens can reveal the derivation apparently compared with that of refraction measure lens. First, this is applicable when there is a difference in the shape and thickness basically and when the lens is used for a short distance. When measure and use it, an astigmatic difference is occurred by the discordant light passage. This is also applicable to optical lens with prism diopter lens and in some cases, must be corrected relating to the diopter incidently.