• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.323-329
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• 2014

Purpose: To understand the pattern of prescribing contact lenses in Korea from 2010 to 2013. Methods: Four hundred survey questionnaires were randomly posted to Korean Optometric clinics for 4 years. The questionnaire was the same form as a form used for International Contact Lens Prescribing Trend. It was also designed to collect information about the contact lenses prescribed to the first 10 patients after its receipt. Results: 1937 fits were used for the analysis among the four hundred survey questionnaires. The average patient age was $26.2{\pm}7.0$ in 2010, $26.1{\pm}7.6$ in 2011, $24.7{\pm}6.6$ in 2012 and $24.8{\pm}7.2$ in 2013. The patients were mainly women (75%). Of all the soft contact lenses, silicon hydrogel lenses were 18% of fits (17% in 2010, 10% in 2011, 20% in 2012, 24% in 2013). By degine, the percentage of toric design lenses accounted for 17% of soft lenses fits and had increased during 4 years (10% in 2010, 18% in 2011, 16% in 2012, 22% in 2013), and cosmetic contact lens made up for 29% (15% in 2010, 20% in 2011, 40% in 2012, 41% in 2013). Conclusions: The contact lenses wearers were mostly women and the average patient age becomes slightly younger. In relation to the increase in the mumber of younger female contact lens wearers,the percentage of cosmetic lenses prescription was much higher (29%) than the global average (7%), and it has gradually increased for last 4 years. This trend could be related to the growth of beauty market in Korea. By emphasizing on toric lens marketing in manufactures, the prescription rate has been gradually increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.76-79
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• 2003

Glass molding is an advantageous method to manufacture glass micro optical components. However, it is difficult to make tungsten carbide core for glass molded micro optics way. We have developed novel method to fabricate tungsten carbide core for glass molding of glass micro optical components. Silicon masters were fabricated by micro machining. Tungsten Carbide cores were fabricated by forming, sintering and coating. Finally we fabricated glass molded V-groove with pitch of 192$\mu\textrm{m}$ and glass microlens way with lens diameter of 36∼225$\mu\textrm{m}$ by the present method.

• Transactions on Electrical and Electronic Materials
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• v.15 no.6
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• pp.344-347
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• 2014

This study was carried out on DLC thin film deposition technology used in infrared optical system production as a method of reducing the shape changes of the molding core and the consequent loss of life. Experiments on the deposition on silicon wafer and tungsten carbide used as a substrate for molding core were conducted at each processing condition using a filtered arc system, and it was found that the surface and mechanical properties were of the greatest quality when the substrate bias voltage of -150 V was used. In addition, it was confirmed that the PV and Ra characteristics were improved by the deposition of the DLC thin film.

• Journal of Applied Reliability
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• v.10 no.2
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• pp.137-148
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• 2010

This study deals with the accelerated life test of high power phosphor converted white Light Emitting Diodes (High power LEDs). Samples were aged at $110^{\circ}C$/85% RH and $130^{\circ}C$/85% RH up to 900 hours under non-biased condition. The stress induced a luminous flux decay on LEDs in all the conditions. Aged devices exhibited modification of package silicon color from white to yellowish brown. The instability of the package contributes to the overall degradation of optical lens and structural degradations such as generating bubbles. The degradation mechanisms of lumen decay and reduction of spectrum intensity were ascribed to hygro-mechanical stress which results in package instabilities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1189-1193
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• 2012

The Miniaturized Fingerprint Imager (MFI) is a slim optical mouse that can be used as an input device for application to wireless portable personnel communication devices such as smartphones. In this study, we have fabricated key optical components of an MFI, including the illumination optical components and imaging lens. An LED beam-shaping lens consisting of an aspheric lens and a Fresnel facet was successfully machined using a diamond turning machine (DTM). A customized V-shaped groove for beam path banding was fabricated by the bulk micromachining of silicon that was coated with aluminum using the shadow effect in thermal evaporation. The imaging lens and arrayed multilevel Fresnel lenses were fabricated by electron beam lithography and FAB etching, respectively. The proposed optical components are extremely compact and have high optical efficiency; therefore, they are applicable to ultraslim optical systems.

• Korean Journal of Optics and Photonics
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• v.28 no.4
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• pp.153-157
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• 2017

An infrared camera and laser common-path optical system is applied to DIRCM (directional infrared countermeasures), to increase boresighting accuracy and decrease weight. Thermal effects of a laser beam in a common-path optical system are analyzed and evaluated, to predict any degradation in image quality. A laser beam with high energy density is absorbed by and heats the optical components, and then the surface temperature of the optical components increases. The heated optical components of the common-path optical system decrease system transmittance, which can degrade image quality. For analysis, the assumed simulation condition is that the laser is incident for 10 seconds on the mirror (aluminum, silica glass, silicon) and lens (sapphire, zinc selenide, silicon, germanium) materials, and the surface temperature distribution of each material is calculated. The wavelength of the laser beam is $4{\mu}m$ and its output power is 3 W. According to the results of the calculations, the surface temperature of silica glass for the mirror material and sapphire for the lens material is higher than for other materials; the main reason for the temperature increase is the absorption coefficient and thermal conductivity of the material. Consequently, materials for the optical components with high thermal conductivity and low absorption coefficient can reduce the image-quality degradation due to laser-beam thermal effects in an infrared camera and laser common-path optical system.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.3
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• pp.200-205
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• 2015

An ultra-precise infrared microscope consisting of a high-resolution infrared objective lens and infrared sensors is utilized successfully to obtain location information on the plane and depth of local heat sources causing defects in a semiconductor device. In this study, multi-layer semiconductor chips are analyzed for the positional information of heat sources by using a lock-in infrared microscope. Optimal conditions such as focal position, integration time, current and lock-in frequency for measuring the accurate depth of the heat sources are studied by lock-in thermography. The location indicated by the results of the depth estimate, according to the change in distance between the infrared objective lens and the specimen is analyzed under these optimal conditions.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.215-221
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• 2023

Among brain CT scan conditions including the lens, the tube voltage was changed to 80, 100, and 120 kVp and applied. The change in dose was analyzed using lead, lead goggles and barium sulfate silicon shielding materials, and the degree of influence of the shielding materials on image quality was compared and analyzed by applying the SNR, CNR, and SSIM index analysis methods. As a result, it was analyzed that although the dose was reduced by applying all shielding materials, the difference in dose reduction was not large (P > 0.05). In addition, as for the change in image quality due to the application of the shielding material, SNR and CNR were the highest when lead goggles were applied, and the structural similarity was measured to be the best as it was closest to the reference value of 1 in SSIM analysis. Therefore, based on the results of this study, it is thought that if more diverse shielding materials and clinical test results are derived and applied, it will be helpful for the clinical application criteria in the case of shielding utilization inspection.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.85-90
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• 2007

We deposited thin films of ZnS(Zinc Sulphide), in which was used antireflection coating material of glasses-lens on silicon and slide-glass substrates using spin coating method, and measured spectra of ellipsometry angles ${\Delta}$ and ${\Psi}$ in the photon-energy range of 1.5~5.0 eV using a variable angle spectroscopic ellipsometer. The optical constants, refractive index and extinction coefficient, of ZnS were determined via the dispersion parameters extracted from the curve-fitting process based on Jellison-Modine dispersion function.