• Journal of IKEEE
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• v.22 no.2
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• pp.432-439
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• 2018

In this paper, an omnidirectional visible light detector was developed by making the detecting surface of a flexible solar cell in a cylindrical form, which has a uniform receiving pattern in the horizontal plane. This solar cell detector receives simultaneously multiple signal lights incident from different directions and provides electrical power to the ASK demodulator in the receiver. In experiments, time division transmission method was used to receive three signal lights incident from different directions to the solar cell detector. Each signal light was ASK modulated using a carrier of 40 kHz, and the synchronizing pulses required for time division transmission were generated by detecting the 120 Hz AC signal included in the indoor illumination lamp with Cds cells. This receiving structure is useful in constructing an $N{\times}1$ optical link in visible light communication.

• Journal of IKEEE
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• v.23 no.4
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• pp.1224-1229
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• 2019

In this study, a liquid crystal (LC) cell was manufactured for smart window applications, such as blinds, and a system for controlling the light transmission rate was developed. The threshold voltage of the LC cell was 1.325 V and when the transmission rate was 10%, the voltage showed 2.370 V, indicating that the LC cell manufactured is driven at low voltage. The LC cell also operated reliably after being heated for 10 min at 80℃. with a response time of less than 30ms. The operation system designed the applied voltage of the LC cell with a interval of about 0.5 V from 0.15 V to 3.53 V and confirmed that the light transmission rate of the LC varies depending on the actual applied voltage. These results suggest that LC cells are likely to be smart window applications.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.119-128
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• 2014

This paper presents a new method for improving the quality of images corrupted by an external source that generates an attenuation and scattering of light like dust, water droplets and fog. Conventional defog methods typically encounter a distortion such that the restored image has low contrast and oversaturation of color in some regions because of the mis-estimated airlight and wrong media transmission. Therefore, in order to mitigate these problems, we propose a robust airlight selection method and local saturation evaluation method for estimating media transmission. The proposed method addresses the wrong media transmission and over-saturation problems caused by the mis-estimated airlight and thereby improves the restored image quality. The results of relevant experiments of the proposed method against conventional ones confirm the improved accuracy of atmospheric light estimation and the quality of restored images with regard to objective and subjective performance measures.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.735-740
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• 2002

In order to improve the anti-fogging property of polymer films, organic-inorganic hybrid coating solutions which have good hydrophilic property and transmission in the range of visible light were synthesized by the sol-gel method. The coating solutions were prepared by adding glycidoxypropyl trimethoxysilane(GPS) to a colloidal silica(15 nm) suspension(Ludox). GPS as silane coupling agent forms strong bonds to the colloidal silica and surrounding polymer matrix and links two different materials together. Solutions prepared by addition of GPS at the acidic condition resulted in coatings that were less prone to cracking, while those at the basic condition caused coatings with more cracking. These resulted in better hydrophilic property and transmission in the range of visible light for the solution prepared at the acidic condition(pH 2). Compared with coatings under acidic conditions, coatings prepared at basic conditions showed worse hydrophilic property and transmission in the range of visible light.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.99-107
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• 2006

The purpose of this study was to investigate the cause of discomfort come from wearing of soft contact lens(SCL) exposed to fundamental cosmetics, After SCLs were smeared with skin lotion, essence lotion or nutritional cream, they were exposed to artificial tear for 7 days, and then changes of the adhered protein amount, the transmission of visible light, the wettability and the base curve were estimated. The amount of protein adhered to SCLs were increased 3 times by being exposed to fundamental cosmetics. Moreover, the transmission of visible light of SCL exposed to both nutritional cream and artificial tear was 92.8%, which was 4.7% lower than SCL exposed only to artificial tear. By being exposed to skin lotion, essence lotion or nutritional cream, the contact angle of SCLs were increased up to $7.1^{\circ}$, $7.0^{\circ}$ or $5.7^{\circ}$ and the base curve of SCLs were decreased to 3.2%, 5.1% or 8.3%, respectively.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.1
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• pp.67-72
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• 2012

In this paper, we present an image enhancement method for atmospherically degraded images using atmospheric light and transmission based on color analysis. We first generate a normalized image using maximum value of each RGB color channel. Then, each atmospheric light is estimated from RGB color channel respectively by calculating reflectance of an image. We also, generate a transmission using gamma coefficients from the Y channel of the image. We can significantly enhance the visibility of an image by using the estimated atmospheric light and the transmission. The proposed algorithm can remove atmospheric degradation components better than existing techniques because the color prevents color distortion which is common problem of existing techniques. Experimental results demonstrate that the proposed algorithm can improve visibility be removing fog, smoke, and dust.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.668-670
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• 2017

Visible Light Communication, which is promising as a next generation near field wireless communications, has been increased study and application case due to the development of LED technology. However, there are few application cases to IoT service due to the necessity of separate equipment for communication and limitation of light transmission to obstacles. In this paper, it propose a portable VLC transceiver module that can be connected to USB OTG and dedicated application for control to realization position possible necessary technique. The string input from the dedicated application is sent to the VLC module via USB OTG to transmit and receive data between the modules. As string transmission experiment result, it is confirmed that ASCII code transmission between VLC transceiver modules is possible through control of the implemented dedicated application.

• Korean Journal of Optics and Photonics
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• v.9 no.1
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• pp.15-19
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• 1998

We have present an all-optical technique to significantly reduce the dispersion penalty of a spectrum-sliced channel in high-speed and long-distance transmissions. We have reduced the necessary optical bandwidth for the 2.5 Gb/s incoherent light transmission down to 0.1 nm by expanding the optical bandwidth of a received signal. The optical bandwidth expansion was realized using the intra-channel fiber four-wave mixing at the receiver resulting in an improvement of th signal-to-noise ratio of the received light channel. We have successfully demonstrated the transmission of a 2.5 Gb/s NRZ signal with the 0.1 nm bandwidth over a 300 km dispersion-shifted fiber. An error floor occurs at $1{\times}10^{-5}$ BER without the optical bandwidth expansion. With the optical bandwidth expansion, however, the error floor decreases to less than $1{\times}10^{-10}$. The transmission penalty was less than 0.5 dB at $1{\times}10^{-10}$ BER. To our knowledge, the optical bandwidth of 0.1 nm used in our experiment is the narrowest optical bandwidth reported so far.

• ETRI Journal
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• v.29 no.6
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• pp.808-810
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• 2007

We demonstrate 10 Gbps optical signal transmission via long-range surface plasmon polaritons (LR-SPPs) in a very thin metal strip-guided geometry. The LR-SPP waveguide was fabricated as a 14 nm thick, 2.5 ${\mu}m$ wide, and 4 cm long gold strip embedded in a polymer and pigtailed with single-mode fibers. The total insertion loss of 16 dB was achieved at a wavelength of 1.55 ${\mu}m$ as a carrier wave. In a 10 Gbps optical signal transmission experiment, the LR-SPP waveguide exhibits an excellent eye opening and a 2.2 dB power penalty at $10^{-12}$ bit error rate. We confirm, for the first time, that LR-SPPs can efficiently transfer data signals as well as the carrier light.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.92-95
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• 2011

The walls of modern train cars are required to have higher transmission loss since modern train have had high speed and light weight. The method based on Reverberation Chamber like KS F 2808 could be used to measure transmission loss. However, this method has difficulty in that constrained Standard of it requires extremely large facilities. Recently, the method based on Scale Reverberation Chamber is used as an alternative to Reverberation Chamber. The method of Scale Reverberation Chamber is known to be small and economical but it provides standing wave that directly influences measurement error. Therefore, this research is focus on predicting standing waves based on method of FFM and reducing measurement error by changing shape of chamber.