• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.1-8
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• 2011

The high efficiency tubular LED lamp has been developed. But, it occurs optical losses in consists of LED package, module, diffuser etc.. By Measuring the tubular LED lamp's luminous flux, we compared and analyzed about the effect of optical losses for each component and actually using measured luminous intensity distribution data, illuminance distribution was simulated by Relux. Optical losses are 24[%] from LED package to luminaire and the tubular LED lamp can be replaced with fluorescent lamp. In this paper, we could provide data for optimum lighting design by analyzing the optical characteristics for developing and propagating the tubular LED lamp.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.140-147
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• 1996

The output of the mach-zehnder optical fiber interferometer varies with birefringences existing in the figer arms. New equations experessing for the visibility of the mach-zehnder interferometer were derived in terms of a number of parameters related to the birefringences, the input SOP and the optical losses. Based on the equations the visibility of the interferometer was simulated in different cases. Some maximum visibility conditons were also presented.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.92-96
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• 2003

Dielectric apertures in vertical cavity laser have been used for improved device performance. Numerical analysis is used to estimate the optical losses as the aperture diameter is reduced. The optical losses depend on the aperture size, thickness and location. The optical loss strongly depend on the aperture size and thickness when the aperture size is similar or smaller than the emitted wavelength. The optical loss is negligible and not depend on the aperture thickness when the aperture size is larger than 5 times emitted wavelength.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.130-131
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• 1999

• Journal of information and communication convergence engineering
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• v.14 no.3
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• pp.163-170
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• 2016

Because of rapid technological advancements, increased data rate support has become the key criterion for future communication medium selection. Multimode optical fibers and multicore optical fibers are well matched to high data rate throughput requirements because of their tendency to support multiple modes through one core at a time, which results in higher data rates. Using the numerical mode solver OptiFiber, we have designed a concentric core fiber by investigating certain design parameters, namely core diameter (µm), wavelength (nm), and refractive index profile, and as a result, the number of channels, material losses, bending losses, polarization mode dispersion, and the effective nonlinear refractive index have been determined. Space division multiplexing is a promising future technology that uses few-mode fibers in parallel to form a multicore fiber. The experimental tests are conducted using the standard second window wavelength of 1,550 nm and simulated results are presented.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.373-378
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• 1995

Bending losses of bent optical waveguides are calculated by virtue of the finite difference-beam p propagation method in the cylindrical coordinate system. In order to minimize the radiating losses of bent optical waveguides, we apply the trench structure to the bent waveguides and perform the a analysis to keep track of: 1) the influence of curvature radius on the bending loss without the trench, 2) the influence of curvature radius and refractive index difference on the bending loss with the trench, 3) the influence of the trench width on the bending loss.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.98-102
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• 2001

To analyze the saturating process of $Cr^{4+}:YAG$ crystal and plastic organic dye as the saturable absorber, we have measured the residual optical losses between a free running and a passive Q-switching mode for various optical densities. The undepleted ground state population density and the saturated transmission of the saturable absorber have been evaluated by the additional optical losses with the increased threshold pump energies between two resonators. ill the passive Q-switching mode, the saturable transmission of saturable absorber is less than the maxrnium saturable transmission due to the undepleted ground state population density. nsity.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.415-416
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• 2008

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.239-248
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• 1995

The method of increasing signal to noise ratio (SNR) in a Hadamard transform spectrometer (HTS) is multiplexing. The multiplexing is executed by a mask. Conventional masks are mechanical or electro-optical. A mechanical mask has disadvantages of jamming and misalignment. A stationary electro-optical mask has a disadvantage of information losses caused by spacers which partition mask elements. In this paper, a mixed-concept electro-optical mask (MCEOM) is developed by expanding the length of a spacer to that of lon-off mask element. An MCEOM is operated by stepping a movable mask. 2N measurements are required for N spectrum estimates. The average mean square error (AMSE) using MCEQM is equal to that using a stationary electro-optical mask without spacers for large N. The cost of manufacturing an MCEOM is lower than that of producing a conventional electro-optical mask because an MCEOM needs only (N + 1)/2 on-off mask elements whereas the con¬ventional electro-optical mask needs N on-off mask elements. There are no information losses in the spectrometers having an MCEOM.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.4-8
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• 2006

Reduction of optical losses in crystalline silicon solar cells by surface modification is one of the most important issues of silicon photovoltaics. Porous Si layers on the front surface of textured Si substrates have been investigated with the aim of improving the optical losses of the solar cells, because an anti-reflection coating and a surface passivation can be obtained simultaneously in one process. We have demonstrated the feasibility of a very efficient porous Si AR layer, prepared by a simple, cost effective, electrochemical etching method. Silicon p-type CZ (100) oriented wafers were textured by anisotropic etching in sodium carbonate solution. Then, the porous Si layer were formed by electrochemical etching in HF solutions. After that, the properties of porous Si in terms of morphology, structure and reflectance are summarized. The surface morphology of porous Si layers were investigated using SEM. The formation of a porous Si layer about $0.1{\mu}m$ thick on the textured silicon wafer result in an effective reflectance coefficient Reff lower than 5% in the wavelength region from 400 to 1000nm. Such a surface modification allows improving the Si solar cell characteristics.