• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.413-419
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• 2023

Light Emitting Diodes(LEDs) are widely utilized not only in lighting but also in various applications such as mobile phones, automobiles, displays, etc. The integration of LED lighting with communication, specifically Visible Light Communication(VLC), has gained significant attention. This paper presents the direct implementation and experimentation of a Vehicle-to-Vehicle(V2V) Visible Light Communication system using commonly used red and yellow LEDs in typical vehicles. Data collected from the leading vehicle, including positional and speed information, were modulated using Non-Return-to-Zero On-Off Keying(NRZ-OOK) and transmitted through the rear lights equipped with red and yellow LEDs. A photodetector(PD) received the visible light signals, demodulated the data, and restored it. To mitigate the interference from fluorescent lights and natural light, a PD for interference removal was installed, and an interference removal device using a polarizing filter and a differential amplifier was employed. The performance of the proposed visible light communication system was analyzed in an ideal case, indoors and outdoors environments. In an outdoor setting, maintaining a distance of approximately 30[cm], and a transmission rate of 4800[bps] for inter-vehicle data transmission, the red LED exhibited a performance improvement of approximately 13.63[dB], while the yellow LED showed an improvement of about 11.9[dB].

• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.159-164
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• 2016

The goal of this study is to implement a communication system that can monitor the status of the nacelle using the power cable itself, without the dedicated communication lines such as an UTP cable and optical fiber for the offshore wind turbine. An inductive coupling powerline communication system for a MW class offshore wind turbine was proposed and its communication performance was demonstrated. The inductive couplers was designed for operation at up to 500 A using a ferrite composite materials. Field test was carried out on the wind farms of Jeju island. Using the iperf communication test program, we have obtained more than 15 Mbps data transmission rate through the 100 m power cable that was installed between the nacelle and the bottom of the power converter. In the data transmission stability test for a week, there was no failure ever. The minimum transmission rate was 15 Mbps and the average data rate was about 20 Mbps. Next, we have installed an infrared camera inside the nacelle in order to measure the temperature distribution and variation of the nacelle. The real-time thermal image taken by the camera was successfully sent to the monitoring system without error.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.5-9
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• 2004

In this paper, we studied the OCT(Optical Coherence Tomography) system which it has been extensively studied because of having some advantages such as high resolution cross-sectional images, low cost, and small size configuration. A basic principle of OCT system is Michelson interferometer. The characteristics of light source determine the resolution and the transmission depth. As a results, the light source have a commercial SLD with a central wavelength of 1,285 nm and FWHM(Full Width at Half Maximum) of 35.3 nm. The optical delay line part is necessary to equal of the optical path length with scattered light or reflected light from sample. In order to equal the optical path length, the stage which is attached to reference mirror is moved linearly by step motor And the interferometer is configured with the Michelson interferometer using single mod fiber, the scanner can be focused of the sample by using the reference arm. Also, the 2-dimensional cross-sectional images were measured with scanning the transverse direction of the sample by using step motor. After detecting the internal signal of lateral direction at a paint of sample, scanner is moved to obtain the cross-sectional image of 2-demensional by using step motor. Photodiode has been used which has high detection sensitivity, excellent noise characteristic, and dynamic range from 800 nm to 1,700 nm. It is detected mixed small signal between noise and interference signal with high frequency After filtering and amplifying this signal, only envelope curve of interference signal is detected. And then, cross-sectional image is shown through converting this signal into digitalized signal using A／D converter. The resolution of the OCT system is about 30$\mu\textrm{m}$ which corresponds to the theoretical resolution. Also, the cross-sectional image of ping-pong ball is measured. The OCT system is configured with Michelson interferometer which has a low contrast because of reducing the power of feedback interference light. Such a problem is overcomed by using the improved inteferometer. Also, in order to obtain the cross-sectional image within a short time, it is necessary to reduce the measurement time for improving the optical delay line.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7B
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• pp.884-890
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• 2001

본 논문에서는 장거리 광 전송로에 대한 시뮬레이션을 효과적으로 빨리 할 수 있는 전파 매개변수 매핑 방법을 제안한다. 이 방법은 많은 광섬유 섹션들과 증폭기들로 구성된 긴 전송로를, 매핑된 전파 매개변수를 갖는 단 하나의 광섬유 섹션의 전송로로 모델링 하는 것이다. 그리고, 본래의 전송로 대신 모델링된 전송로를 사용하여 시뮬레이션을 하고 성능을 분석한다. 그것의 성능을 eye diagram, 정상 시뮬레이션과 제안된 매핑 방법에 의한 eye-opening 들의 차이, 시뮬레이션 시간의 감소 정도를 통해 확인한다. 시뮬레이션 결과에서 이 방법은 정상 시뮬레이션과 비교할 때 3% 이내의 eye-opening 차이를 가질 만큼 광 신호의 전파특성을 정확하게 서술하고 시뮬레이션 시간은 광섬유 섹션의 수가 20일 때 정상 시뮬레이션의 34.72%로 감소시켜 주는 것을 확인하였다.

• ETRI Journal
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• v.34 no.6
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• pp.838-846
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• 2012

This paper proposes a cost-effective hybrid-type power budget extender (PBEx) that can provide a high power budget of over 45 dB in an asymmetric 10-Gb/s Ethernet passive optical network (10/1G-EPON). The hybrid-type 10/1G-EPON PBEx comprises a central office terminal (COT) and remote terminal (RT) module supporting four channels and uses a coarse wavelength division multiplexing (CWDM) technology between the COT and RT for a reduction of fiber cost and efficient access network design. The proposed 10/1G-EPON PBEx can provide over a 40-km reach and 128-way split per CWDM wavelength with no modification of a legacy 10/1G-EPON system and can satisfy the error-free service in $10^{10}$ packet transmission.

• ETRI Journal
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• v.35 no.5
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• pp.927-930
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• 2013

We propose a visible light communication system in which the color and brightness are controllable. Pulse width modulation and variable pulse position modulation (VPPM) schemes are used to control the color and brightness, respectively. A digital algorithm to decode VPPM signals is suggested and implemented. A seamless transmission is observed in a testbed experiment under various environmental conditions. The proposed scheme can be applied to emotional-lighting-based wireless optical communication.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.133-140
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• 2015

Neural stimulating implantable medical devices (IMDs) have been widely used to treat neurological diseases or interface with sensory feedback for amputees or patients suffering from severe paralysis. More recent IMDs, such as retinal implants or brain-computer interfaces, demand higher performance to enable sophisticated therapies, while consuming power at higher orders of magnitude to handle more functions on a larger scale at higher rates, which limits the ability to supply the IMDs with primary batteries. Inductive power transmission across the skin is a viable solution to power up an IMD, while it demands high power efficiencies at every power delivery stage for safe and effective stimulation without increasing the surrounding tissue's temperature. This paper reviews various wireless neural stimulating systems and their power management techniques to maximize IMD power efficiency. We also explore both wireless electrical and optical stimulation mechanisms and their power requirements in implantable neural interface applications.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.101-101
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• 2003

다목적 실용위성 1호에 탑재된 EOC(Electro-Optical Camera)는 2,000년부터 현재까지 한반도 인근 및 세계의 주요 육지 지역을 관측하고 있다. DOC는 크게 광학부(Sensor Assembly)와 전자부(Electronics Assembly)로 구성되어 있으며, 지상으로부터 입사하는 광 정보를 디지털 신호로 재구성하여 PDTS(Payload Data Transmission System)을 통해 지상으로 전송한다. EOC 광학부는 2,592개의 CCD(Charge-Coupled Device) 센서들로 구성된 선형 시스템이며, push-broom 주사 방식으로 구동된다. 한편, EOC의 임무 전, 후로 Aperture Cover Mechanism에 의해 EOC의 덮개를 덮은 상태로 짧은 시간동안 촬영을 수행, 획득된 영상 역시 지상으로 전송한다. 이러한 영상들은 EOC 영상에 포함되어 있는 암전류(Dark Current)에 대한 간접적인 정보를 제공하며, Dark Calibration Data로 정의된다. Dark Calibration Data는 지상에서 수신된 후, EOC 영상에 대한 복사 보정에 이용된다. 본 연구에서는 EOC Dark Calibration Data에 대한 분석을 통해, EOC 영상 내의 잡음 성분을 분석한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.504-508
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• 2000

본 연구는 WDM(wavelength-division-multiplexed) 전송 시스템에서 안정된 파장의 광 송신기를 설계하고 구현하기 위한 것이다. 기본적으로 광 출력의 안정성을 위하여 10uA 미만의 안정성을 갖는 정전류 회로를 설계하려 했으며, 출력되는 광의 파장은 Wavelength Locker를 이용 에러신호를 검출하고, 이 신호로 레이저 다이오드 모듈 내부의 온도를 제어하여 파장을 조절하였다. 최종적으로 이들은 A/D, D/A 컨버터와 $\mu$-Processor로 구성된 마이컴 회로를 통해서 제어되도륵 하였다. 또한 마이컴 회로는 송신기가 WDM 전송 시스템에 장착되었을 때의 시스템과의 인터페이스를 위한 신호들을 출력할 수 있도록 하였다.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.933-935
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• 1987

We have developed 140Mb/s and 565Mb/s muldexes as parts of a 565Mb/s Optical Fiber Transmission System. Bunched frame structures are used for these muldexes. In this paper we describe their frame synchronization performance.