• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.207-212
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• 2010

Purpose: Rigid gas permeable (RGP) contact lenses, based on fluorosilicone acrylate, were treated with plasma in air. Methods: The chemical compositions were analyzed by using X-ray photoelectron spectroscopy (XPS), the surface morphology and roughness of RGP contact lenses were observed by using atomic force microscopy (AFM), and the wettability changes were estimated by wetting angle measurement. Results: As the contact lenses were treated by the plasma, the F contents decreased significantly, and the O and Si contents increased on the surface. The number of oxygen-containing hydrophilic radicals (C-O and Si-O) increased greatly, the hydrophobic surface decreased, and the wetting angle increased. But the C-O bonds created with exchange of the fluorine did not increase a wettability. The surface compositions were not remarkably changed for the 6 months after plasma treatment, but the wetting angle increased again. Conclusions: It was considered that the improved wettability of the RGP contact lenses of high fluorine content after plasma treatment was affected by the activation of surface, the increase of Si-O, and the decrease of hydrophobic surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.183-183
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• 2009

본 연구에선 ITO에 사용되는 Indium의 양을 줄이기 위해 ITO와 유사한 성질을 보이는 조성인 Indium - Zinc - Tin Turnary compound를 연구하였다. 각 조성은 Indium - Zinc - Tin Turnary compound를 기본으로 하여 Zinc site에 이종원소인 Al2O3와 Ga2O3를 doping함에 따라 변화되는 전기적 특성을 살며보았다. 분석에 사용한 Ceramic pellet은 일반적인 Ceramic process를 거쳐 제작되었다. 각 조성의 전기적 특성은 TCR meter와 Hall effect analyser를 이용하여 측정하였고, X-ray diffraction measurements(XRD), Scanning Electron microscope(SEM)를 이용하여 결정학적 특성을 분석하였다.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.155-161
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• 2002

We studied the formation of nickel nano thin film that have various electrochromic properties. Nickel thin film having various thickness will apply photoelectronic devices, specially, electrochromic devices. These devices will apply lens, battery, glass and solar cell that have light, thin, simple and small that applied nanotechnology and quantum dot. Nickel thin film was coated by electrochemical method on ITO electrode. We studied the thin film properties by Cyclic voltammetry, Chronoamperometry. Impedance. X-ray diffraction analysis and Atomic force microscopy.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.111-114
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• 2001

This paper presents the influence of the additive composition on flexural strength and hardness of SiC-TiC composites materials for spectacle lens cutting materials. The materials were hot-pressed at $1800^{\circ}C$ and subsequently annealed at $1910^{\circ}C$ for 3h. The heating rate was $15^{\circ}C/min$ and the cooling rate about $25^{\circ}C/min$ in from the sintering temperature to $1300^{\circ}C$. The growth of particles of spectacle lens cutting materials was analysed by SEM and crystalline phases were discussed by x-ray diffractometry. Typical fracture toughness and hardness of materials for spectacle lens cutting were $6.1MPa{\cdot}m^{1/2}$ and 14.9 GPa, respectively.

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.13-18
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• 2000

The SiOxNy thin films were prepared on Si(lOO) by reactive RF sputtering method. The reactive gas ratio and the power were used as parameters for depositing SiOxNy thin fims. The properties of ${SiO_x}{N_y}$ thin tilms were investigated by XRD, XPS, refractive index and extinction coefficient analyzer (n'||'&'||'k analyzer), and FfIR. It was found by the results of the x-ray diffraction measurement that SiOxNy thin films were grown to an amorphous structure. From the results of the XPS, and the n'||'&'||'k analyzer, it was found that refractive index was intended to increase with the increasement of the relative nitrogen contents of the ${SiO_x}{N_y}$ thin films.

• Journal of the Korean Ceramic Society
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• v.49 no.3
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• pp.205-215
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• 2012

It has been studied the crystal and block structures of the hexagonal ferrites with M, W, Y and Z types prepared by various coprecipitation-oxidation method. The structures have been refined with a Rietveld analysis of the powder X-ray diffraction pattern with high precision ($R_{WP}$ <0.09, $R_I$ <0.03). The density difference between the S-blocks was proportioned to the cobalt contents in hexagonal ferrites, but that between the R or T-blocks was relatively small. Compared with the blocks and cation-oxygen polyhedra in BaM ($BaFe_{12}O_{19}$), those were bulky to the normal direction for the c-axis in $Co_2W$ ($BaCo_2Fe_{16}O_{27}$) and to the parallel direction for the c-axis in $Co_2Y$ ($Ba_2Co_2Fe_{12}O_{22}$) and $Co_2Z$ ($Ba_3Co_2Fe_{24}O_{41}$). The S-blocks of $Co_2W$, $Co_2Y$, and $Co_2Z$ were unstable and distorted. Because the T-block of $Co_2Z$ was unstable, the T-block was decomposed into the Ba-rich phase and $Co_2W$ at high temperatures above $1200^{\circ}C$. A standard powder X-ray diffraction pattern for $Co_2Z$ was proposed as well.

• Journal of the Korean Magnetics Society
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• v.18 no.2
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• pp.63-66
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• 2008

In order to the magnetization and magnetic entropy change for superparamagnetic ferrite nanoparticles, ultrafine cobalt ferrite particles were synthesized using a mircoemulsion method. The peak of X-ray diffraction pattern corresponds to a cubic spinel structure with the lattice constant 8.40 $\AA$. The average particle size, determined from X-ray diffraction line-broadening using Scherrer's, is 7.9 nm. The maximal magnetizations measured at 5 and 300 K are 24.3 emu/g and 17.2 emu/g, respectively. Superparamagnetic behavior of the sample is confirmed by the coincidence of the M vs. H/T plots at various temperatures. According to the thermodynamic theory, magnetic entropy change decreases with increasing temperature.

• Current Optics and Photonics
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• v.2 no.1
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• pp.79-84
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• 2018

We present a novel and simple method to enable spatially selective $ZnAl_2O_4$ nanocrystal formation on the surface of $B_2O_3$-$Al_2O_3$-ZnO-CaO-$K_2O$ glass by employing localized laser heating. Optimized precipitation of glass-ceramics containing nanocrystals doped with $Eu^{3+}$ and $Yb^{3+}$ ions was performed by controlling $CO_2$ laser power and scan speed. Micro-x-ray diffraction and transmission electron microscopy revealed the mean size and morphology of nanocrystals, and energy dispersive x-ray spectroscopy showed the lateral distribution of elements in the imaged area. Laser power and scan speed controled annealing temperature for crystalization in the range of 1.4-1.8 W and 0.01-0.3 mm/s, and changed the size of nanocrystals and distribution of dopant ions. We also report more than 20 times enhanced downshift visible emission under ultraviolet excitation, and 3 times increased upconversion emission from $Eu^{3+}$ ions assisted by efficient sensitizer $Yb^{3+}$ ions in nanocrystals under 980 nm excitation. The confocal microscope revealed the depth profile of $Eu^{3+}$ ions by showing their emission intensity variation.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.340-351
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• 1995

Electrical, physical and optical properties of Aluminum(Al), Copper(Cu) thin films were investigated in order to establish the optimum sputtering parameters in Liquid Crystal Display (LCD) panel applications. DC-magnetron sputtered film on coming 7059 samples were fabricated with variations of deposition power densities, deposition pressures and substrate temperatures. Low resistivity films(AI;2.80 .mu..ohm.-cm, Cu:1.84 .mu..ohm-cm),which lower than the reported values, were obtained under sputtering parameters of power density(250W), substrate temperature(450-530.deg. C) and 5*10$\^$-3/ Torr deposition pressure. Expected columnar growth and stable grain growth of both films was observed through the Scanning Electron Microscope(SEM) micrographs. Dependency of the applicable defect-free film density upon depositon power and temperature was also characterized. Not too noticable variations in X-ray diffraction patterns were remarked under the alterations of sputtering parameters. High optical reflectivities of Al, Cu films, approximately 70-90 %, showed high degree of surface flatness.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.73-77
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• 2008

Purpose: This research is that prepare amorphous or crystalline ZnO thin films with pure strong UV emission on soda-lime-silica glass (SLSG) substrates by low-temperature annealing. Methods: Growth characteristic and optical properties of the amorphous or nano-crystalline ZnO thin films prepared on soda - lime - silica glass substrates by chemical solution deposition at 100, 150, 200, 250 and $300^{\circ}C$ were investigated using X-ray diffraction analysis, ultraviolet - visible - near infrared spectrophotometer, and photoluminescence. Results: The films exhibited an amorphous pattern even when finally annealed at $100^{\circ}C{\sim}200^{\circ}C$ for 60 min, while crystalline ZnO was obtained by prefiring at 250 and $300^{\circ}C$. The photoluminescence spectrum of amorphous ZnO films shows a strong NBE emission, while the visible emission is nearly quenched. Conclusions: These results indicate it should be possible to cheaply and easily fabricate ZnO-based optoelectronic devices at low temperature, below $200^{\circ}C$, in the future.