• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.306-313
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• 2021

We study the amplification properties of an optical amplifier based on a cesium-vapor cell. An optical amplification system including cesium vapor mixed with a buffer gas is built, and its amplification feature is investigated as a function of the size of the incident beam and the temperature of the cesium-vapor cell. We observe that the optical amplification properties, such as amplification factor and extraction efficiency, change significantly depending on the temperature and beam diameter of the pump and seed light. A maximum extraction efficiency of 56% is obtained when the temperature of the cesium cell is 90 ℃, with a 200-㎛ diameter of the pump (500 mW) and seed light (10 mW). The numerical simulation of the amplification properties agrees reasonably with the results obtained from the experiment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.4
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• pp.1-10
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• 2014

In papermaking industry, inorganic fillers are widely used for the purpose of improving opacity, brightness, printability, uniformity and dimensional stability. They are also useful for production costs and energy savings. In the past, inorganic fillers in papermaking industry only focused on micro-scale but recently, new trials on nano-powdered technology are applying. Even nano-powdered fillers are rapidly utilized for improving the optical and surface properties in coating and surface sizing, there still have some problems in wet-end process due to poor dispersibility and retention. In this study, nano-particled calcium carbonate was produced by milling the PCC and its applicability between micro sized and nano sized calcium carbonated was compared in wet-end process, and finally the sheet properties were evaluated. Nano-PCC was not retained in sheet structure without applying retention system, but with retention system nano-powdered PCC was absorbed on fiber surface with expanding the fiber networks. The application of PAM-bentonite system has resulted in high ash retention and bulky structure for copier paper, and good optical properties in brightness and opacity. However, it required to solve the weakness of low tensile property due to interruption of hydrogen bonding by nano fillers.

• Journal of Fashion Business
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• v.6 no.5
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• pp.1-11
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• 2002

Today, great percentage of apparel fabrics comprise knit products. A few apparel items are almost exclusively made from knit products including sweaters, T-shirts, lingerie, and hosiery. In weft knits, intermeshing yarn traverses the fabric crosswise. The production rate of knitting machines is about four times higher than that of conventional looms iin proportion to the amount of fabric produced per unit time. Knit apparels fabrics are noted for freedom of body movement, easy-care, resilience, soft draping and quality. The appearance of fabrics is of prime importance along with tactile features such as smoothness, crispness, stiffness when we deal with the handling evaluation of the textiles. In practice, the quality and performance of fabrics judged by sighted evaluators, and it is perhaps logical, in attempting to establish an effective fabric objective measurement system. It is worthwhile to make objective measurement that correlate well with subjective evaluations made by sight and touch together. However, it often imposes difficulties to effectively measure and analyze the appearance or optical properties of the textile surface features. In this study, an attempt is made to provide a preliminary approach to the analysis of the gloss property, which is one of the optical properties of fabrics. The specimens range from 70/24 nylon 6 filament yarn knit fabric to 70/68 nylon 6 filament yarn knit fabric, the latter being finer. A few three-dimensional models based on Peirce's model of knit stitch have been proposed and material properties were given to calculate the properties. Goniophotometric measurements of the specimens were also carried out.

• Journal of Information Display
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• v.9 no.1
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• pp.26-32
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• 2008

The dependence of optical performances of collimating films such as prism films and pyramid films on the reflecting properties of reflection films were investigated by using a ray tracing technique. The angular distribution of the luminance and the on-axis luminance gain were obtained by using a simple backlight model composed of a reflection film, a virtual flat light source, and a collimating film. Three kinds of reflecting properties were used, which were a perfect Lambertian reflector, a perfect mirror reflector, and a reflector having both diffuse and specular properties. It was found that the on-axis luminance gain was the highest in the simulation where a mirror reflector was used, while the viewing angle was the widest where the Lambertian reflector was used. This result indicates that it is necessary to optimize the simulation condition such as the reflecting properties in order to predict the optical performances of collimating films accurately. Quantitative correlation between the optical characteristics of collimating films and the reflecting properties of reflection films can be used to improve simulation technique for the development and the optimization of collimating films for LCD backlight applications.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1113-1119
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• 2003

We used isopropanol which has low boiling point to prepare thin films at low temperature and changed mole concentration of zinc acetate from 0.3 to 1.3 mol/l. The structural, optical and electrical properties of ZnO thin films with Zn content were investigated. ZnO thin films highly oriented along the c-axis were obtained at Zn concentration of 0.7 mol/l. ZnO thin films with Zn concentration of 0.7 mol/l showed a homogeneous surface layer of nano structure. The transmittance of ZnO thin films by UV-vis. measurement was about 87% under the Zn concentration of 0.7 mol/l, but rapidly decreased over the 1.0 mol/l. The optical band gap energy was obtained from 3.07 to 3.22 eV which is very close to the band gap of bulk ZnO (3.2 eV). The electrical resistivity of ZnO thin films was about 150 $\Omega$-cm that shows little difference with Zn concentration. I-V curves of ZnO thin films exhibited typical ohmic contact properties.

• Transactions of Materials Processing
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• v.18 no.2
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• pp.128-134
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• 2009

The present study covers an integrated simulation method to evaluate optical performance of an aspheric plastic lens by connecting an injection molding analysis with a ray tracing simulation. Traditional ray tracing methods have based on the assumption that the optical properties of a lens are homogeneous throughout the entire volume. This assumption is to a certain extent unrealistic for injection-molded plastic lenses because material properties vary at every point due to the injection molding effects. To take into account the effects of the inhomogeneous optical properties of the molded lens, a numerical scheme is developed to calculate the distribution of refractive index induced from the injection molding process. This index distribution is then reflected onto CODE $V^{(R)}$ simulation and used to calculate ray paths in inhomogeneous media. The proposed tracing scheme is implemented on the tracing of an aspheric lens for a mobile phone camera module.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.21-25
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• 1998

We investigated the optical properties of lead zirconate($PbZrO_3$, PZ) thin films. The PZ films for the measurement of optical properties were prepared on ITO glass by sol-gel method. By post annealing, with annealing temperature $T=700^{\circ}C$, the pyrochlore phase of as-deposited specimen was transformed into the perovskite phase. The surface of films were plat, transmittance were from 60 to 80% at 480~2000nm, and refractive index were from 2.1 to 1.9 at 480~1000nm.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.147-150
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• 1994

To predict light propagation in biological tissues irradiated by laser, the optical properties such as absorption and scattering coefficients are required. There have been various techniques for measuring these coefficients. One method requires tissue samples, often a slab of thin tissue, is invasive. On the other hand, non-invasive method usually measures back-scattered light from a subject with no physical intervent ions. Advantages and disvantages of using different methods are investigated. A careful attention should be made in order to select the best method for a given experimental condition since, even either for invasive or non-invasive method, accuracy is subject to governing models and sample preparations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.119-122
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• 2001

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique at the oxygen pressure of 350 mTorr. In order to investigate the effect of post-annealing treatment with oxygenn pressure of 350 mTorr on the optical property of ZnO thin films, films have been annealed at various substrate temperatures after deposition. After post-annealing treatment in the oxygen ambient, the optical properties of the ZnO thin films were characterized by PL(Photoluminescence) and structural properties of the ZnO were characterized by XRD, and have investigated structural property and optical property for application of light emission device.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.25-26
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• 2006

Azobenzene functionalized polymers have been extensively investigated due to the potential applications in the areas of optical switching, optical elements, optical information storage, and nonlinear optics. These applications are mainly achievable due to photoinduced properties of azobenzene groups with photoisomerization and photoinduced anisotropy. We report applications to the optoelectronic devices using inscribed one-(1D) and two-dimensional (2D) SRGs on azo polymer films. The inscribed holographic SRGs patterns were useful to control or enhance optoelectronic properties such as transparent electrode patterning, hybrid solar cell and ultraviolet GaN-based LED.