• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.281-282
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• 2006

In wide angle diffuser, the increasement of cross-sectional area so rapidly cause possibly separate from the diffuser wall and forming areas of backflow. The flow characteristics of wide angle diffuser with guide damper was investigated for three kind of inclined angle($\alpha=7_{\circ},\;10.5_{\circ}\;and\;14_{\circ}$)of guide damper. Judging from the results, guide damper can be used as an effective means of improvement for diffuser performance and inclined angle of $\alpha=10.5^{\circ}$ was through to be the best among three cases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1251-1260
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• 2008

Diffuse wireless optical communication offers more robust optical links in terms of coverage and shadowing than line-of-sight links. However, traditional diffuse wireless infrared (IR) transceiver systems are more susceptible to multi-path distortion and great power decrease, which results in limiting high-speed performance. Multi-beam is an effective technique to compensate for multi-path distortion in a wireless infrared environment. The goal of this paper is to analyze the transmission characteristics by replacing traditional diffuse system (TDS) which contains single wide angle transmitter and single element receiver by system consisting of three-beam transmitter and non-imaging receiver (TNS) attached with compound parabolic concentrator (CPC). In the simulation, we use the recursive model developed by Barry and Kahn and build the scenario based on 10 different cases which have been listed in Table 1. Moreover, we also check the reliability of the TNS diffuse link channel by BER test on the basis of different receiver positions and room sizes. The simulation results not only show the basic transmission characteristics of TNS diffuse link, but also are references to design more efficient and reliable indoor infrared transmission systems.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.421-425
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• 2007

A new 3D rear projection display system using double-layer polarization-selective screen systems, one stacked in front of the other, has been developed. The front and rear screens are made of scattering polarizer films, and they either diffuse-scatter or transmit the incident light depending on the polarization state of the light. The near and for images are projected onto the front and rear screens, respectively, using light waves with mutually orthogonal polarization states. The new display system produces clear high-resolution images, which are visible over a wide range of viewing angle. It was found that the impression of depth is pronounced and eyestrain is only comparable to that by 2D display systems.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.245-248
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• 2007

We report a novel optical structure for bottomemitting white OLEDs. The structure includes, reformulated color filter, dielectric mirror to enforce cavity resonance, and micro-scatterer to extract more light and diffuse the viewing angle dependency. With the new structure, the color gamut was 104% of that of NTSC, the combined transmission efficiency of the color filter was 83%/3 and the color shift at $45^{\circ}$ was maintained below 0.02 in the 1976 CIE color space. The color performance of White OLED + color filter system can match comparably that of RGB OLED + microcavity system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.32-39
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• 2014

In general, non-directional LED lamps including high transmittance cover are more advantageous than directional LED lamps, which are efficient enough to improve luminous efficacy and obtain certification, allowing wide manufacture, sale, and distribution. Although KS C 7651(Self-ballasted LED lamps-Safety and performance requirements) was revised in July 2013, however, many companies are having a lot of difficulties in keeping the certification and product development for the lack of the photometric analysis for non-directional LED lamps. In this paper, through the measurement of the angular distribution of luminous flux of incandescent lamp and non-directional LED lamps, we examined the reasonability of non-directional LED lamps' standards as suggested in KS C 7651. According to the results, even if non-directional LED lamps satisfy KS C 7651, when compared to an incandescent lamp, they showed less diffusive than the incandescent lamp and the distribution of the luminous flux depending on the angle fluctuated greatly even among LED lamps. Judging by the result, the current standard of the non-directional LED lamps, KS C 7651, has been comprehended that the angular distribution of the luminous flux needs to be presented after being much more thoroughly standardized.