• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.141-144
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• 2002

Computer code was developed to design waveguide gratings based on coupled-mode equations and the transfer matrix formalism. The experimental set-up has been constructed for inscribing Bragg gratings in planar waveguides with a phase mask and uv laser beam, which enables alignment and packaging of grating devices as well as in-situ performance measurements. Bragg grating has been fabricated on silica planar waveguides with 0.75% Germanium concentration and its transmittance spectrum was measured to have 95% reflectance at the peak wavelength. Optical losses as the function of the misalignment were measured and their usage is described.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.403-406
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• 2005

We optimized a patterned-vertical-alignment (PVA) transflective liquid-crystal (LC) cell for small pixel application. To achieve the high resolution display performance in the mobile communication equipments such as mobile phones, personal data assistants, and tablet personal computers, we optimized the parameters of liquid crystal and the electrode structure. Both the transmittance and the reflectance are maximized at the same time.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.33-40
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• 2011

In this study, it is quantitatively analyzed for thermal Characteristics of isolation-heat paint which has been supplied to a domestic market through experiments and simulations. In the case of experiment using the container box, it shows 8% decrease on cooling energy consumption in a summer season, but shows increase on heating energy consumption. As a result, the analysis has found increase of energy consumption. As a result of holding simulations with meteorological data of domestic major cities, it shows an increase of energy consumption in domestic condition, and it is hard to expect an energy saving from the isolation-heat paint unless greater air-conditioning load.

• ETRI Journal
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• v.37 no.6
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• pp.1129-1134
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• 2015

In this article, a study of a flower like nanostructured CdS buffer layer for improving the performance of a submicron-thick $CuIn_{1-x}Ga_xSe_2$ (CIGS) solar cell (SC) is presented. Both its synthesis and properties are discussed in detail. The surface reflectance of the device is dramatically decreased. SCs with flower like nanostructured CdS buffer layers enhance short-circuit current density, fill factor, and open-circuit voltage. These enhancements contribute to an increase in power conversion efficiency of about 55% on average compared to SCs that don't have a flower like nanostructured CdS buffer layer, despite them both having the same CIGS light absorbing layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.10-13
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• 2009

We have developed variety of LCD technologies for the out-door display, which improve out-door readability as well as reliability from external impacts. This improvement was made possible by new approach on LCD cell optical design and modification of LCD surface, which allows surrounding light to be transmitted to enhance the visibility and at the same time filtering out light, which are considered to be source of noise in terms of visibility. This technology enables users to maintain high display performance in both in-door & out-door environments moreover alternatively choosing in-door/out-door.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.15-20
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• 1999

A spectrophotorreter using two-beam type integrating sphere is developed, and the measurerrent accuracy is analyzed. The efficiency of the integrating sphere is analyzed, and the relation between the efficiency and the total measurerrent error is found. Especially, the integrating sphere is fabricated on the basis of its characteristics according to its shape such as the sample port. The perfonnance of the developed spectrophotorreter is tested using a black and a white standard reflectance plate, and the measurerrent error of $\pm0.5%$ is obtained.tained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.5
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• pp.13-20
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• 2012

The light transmittance of optical device is one of the important conditions to improve the product performance and it has researched through the various methods. One of these methods to improve the optical transmittance is to use a pattern on optical surface. The advantages of this method are to simplify the manufacturing process and to easy mass production. If a surface of glass has with the proper patterns, we can expect a great effect on optical transmittance. The purpose of this research is to derive a pattern to get high transmittance from a theoretical approach and to analyze the transmittance through the simulation. And then, we made a sample with a pattern and compared with the results from simulation and experiment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.421-422
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• 2007

The fringe electric field driven transflective liquid crystal display with dual orientation has a problem that the voltage-dependent transmittance and reflectance curves do not match each other, requiring a dual driving circuit to achieve a high electro-optic performance. Optimizations of the electrode structure in the array substrate and rubbing direction solve this problem so that the transflective display with a single gap and a single gamma curve for reflective and transmissive region is possible.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.4-8
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• 2011

We have evaluated the performances of bidirectional optical amplifiers which were suited for the cost-effective implementation of amplified bidirectional passive optical networks (PONs). First, we measured the maximum gains of two simple bidirectional optical amplifiers implemented without using any optical components for the suppression of reflected signals. From the results, the maximum gains of two simple bidirectional amplifiers with a broadband light source (BLS) seeded optical source were limited to be 27 dB due to the reflection-induced in-band crosstalk, when the reflectance coefficients were measured to be -33 dB in both directions. Then, we have also implemented a bidirectional optical amplifier with two band splitters for the amplified bidirectional PON where the two different wavelength bands were allocated to the downstream and upstream signals transmission. In our measurement, we confirmed that the maximum gain of bidirectional optical amplifier with two band splitters could be increased to more than 30 dB owing to the efficient suppression of in-band crosstalk.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.98-104
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• 2024

In order to overcome the urban heat island effect, highly functional paint is attracting attention as a promising means by shielding heat on the structure (building) surface. When a paint was prepared containing nano-sized silica particles, the heat-insulating performance was relatively higher than that of paints with other sizes. In addition, developed paints showed enhanced properties such as chemical resistance and abrasion resistance test because of the presence of nano-sized silica included in functional paint.