• Electronics and Telecommunications Trends
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• v.19 no.6 s.90
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• pp.13-23
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• 2004

각종 대용량 디지털 멀티미디어 기기의 보급과 사용자 주변 환경의 네트워크화에 따라 고밀도 환경에서 고품질 광대역 무선 서비스를 제공할 수 있는 광무선 통신 기술이 유비쿼터스 네트워크를 실현할 유망기술로 부각되고 있다. 전파를 사용한 무선통신 방식에 비해 무한대에 가까운 대역폭과 보안성을 갖는 광무선 통신 기술의 특성과 기본 원리를 소개하고, 지금까지 개발된 기술 수준과 활용 현황 및 고성능광무선 통신 기술의 실용화를 위해 우선적으로 해결해야 할 기술적 과제들과 최근 연구개발 동향을 살펴본다.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1111-1116
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• 2012

At present, indoor optical wireless communications using LED lightings has been widely studied. The combination of this technology to the low voltage powerline grid installed in each home makes an efficient method for fulfilling the premise of broadband access for home networking. In this paper, white LEDs were used for both illumination and remote-control, so that information can be broadcast within a room for control the optical wireless systems. We implemented a model car to evaluate the performance of optical wireless remote-control. The requirement for levels of illumination suitable for communication were investigated and applied to design the test-bed. In spite of limitation of line-of-sight communications, it will open up new applications to the optical wireless remote control system in an electromagnetic interference region.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.173-177
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• 1998

Under indoor environment, in case that wireless optical LAN does not obtain the line-of-sight between transmitter and receiver, hemi-spherical lens or reflector must be adopted to get broader beam width. The beam tilt and the fluctuations in amplitude and phase of optical signal through indoor-space occur due to the turbulene. This fading often results in unacceptably large bit error probabilities and thus performance degradation of wireless optical communications. In this paper, when the spherical filter at the front-end of transmitter and receiver is used for wireless optical channel not satisfying line-of-sight, the signal-to-noise ratio as to zenithal angle and the effect from the turbulence due to indoor temperature are investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.425-430
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• 2013

Robust and high speed underwater communication is severely limited when compared to communications in terrestial. In free space, RF communication operates over long distances at high data rates. However, the obstacle in seawater is the severe attenuation due to the conducting nature. Acoustic modems are capable of long range communication up to several tens of kilometers, but it has low data-rate, high power consumption and low propagation speed. An alternative means of underwater communication is based on optics, wherein high data rates are possible. In this paper, the characteristics of underwater channel in the range of visible wavelength is investigated. And the possibility of optical wireless communication in underwater is also described. The LED-based transceiver and CMOS sensor module are integrated in the system, and the performance of image transmission was demonstrated.

• Electric Engineers Magazine
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• v.236 no.4
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• pp.19-24
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• 2002

통신기기의 앞뒤에 서지방지기를 설치하고 서지방지기의 접지선을 통신기기에 연결하지 않고 서지방지기끼리 연결하고 한쪽의 접지선으로 유입된 서지가 다른 서지방기기의 접지선으로 전이되도록 하는 방식이다. 이것은 선로에 유입된 서지를 기기를 우회하여 다른 회선으로 흐르게 하는 방식이다.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.138-155
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• 1997

Wireless optical communication is able to obtain high antenna gain as well as utilize to transmit the high-speed information with large capacity than the RF communication. However, the propagation path (atmosphere) is considered as an attenuator occured turbulence, absorption and scattering. These undesired phenomena diminish the amount of light that is collected at the receiver. To evaluate the effect of the atmospheric turbulance and scattering, this paper perform the ground-to-ground wireless optical LAN experiment by using the (2,1,6) convolutional coder and Viterbi decoder, and analyze numerically the earth-station antenna diameter due to the propagation path condition and upstream/downstream link.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.164-175
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• 2008

Atmospheric effects on laser beam propagation can be broken down into two categories: attenuation of the laser power and fluctuation of laser power due to laser beam deformation. Attenuation consists of scattering of the laser light photons by the fog. Laser beam deformation occurs because of small-scale dynamic changes in the index of refraction of the atmosphere. This causes pointing error. In order to analyse these effect on optical wireless communication system, in this paper uses cassegrain optics as a transmitting and receiving telescope, AID as a detecting device and ill as a light source. The signal modulating and demodulating method is a IM/DD. I show the effects of fog and pointing error and calculate the possible communication distance for BER is $10^{-9}$.

• Electronics and Telecommunications Trends
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• v.20 no.6 s.96
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• pp.15-23
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• 2005

최근 국내외에서 연구되고 있는 가입자에 초고속 멀티미디어 서비스가 가능하도록pico cell 가입자 통신망을 구성하여 100Mbps-수 Gbps의 대용량 초고속 데이터를 통신할 수 있는 밀리미터파 pico cell 광무선 통신 기술의 개념, 필요성, 기술 동향과ETRI를 중심으로 연구 개발되고 있는 핵심 부품들의 개발 현황과 기술의 활용성에 대하여 조사하였다.

• Photonics industry news
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• s.3
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• pp.54-55
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• 2001

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1840-1846
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• 2014

An experimental outdoor optical wireless data communication system with an optical filter in the presence of sunlight or artificial light is presented. For the efficient blocking of light noise outdoors, we employ an optical filter made of microlouver film on the top of the photo diode. This filter is designed to block any light noise incident from an angle higher than $30^{\circ}$ on the assumption that light noise does not face the photo diode horizontally. Outdoor experiments daytime with the optical filtering have been conducted. The experimental results demonstrate that the optical filter effectively blocks nearly all light noise incident from the specified angle or higher and more than 90% of the transmitted data packets are successfully received. The proposed outdoor visible light data communication can thus facilitate a practical free space outdoor optical wireless data transmission.