• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.150-151
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• 2014

본 논문에서는 OLT (optical line termination)와 다수의 ONU (optical network unit)로 구성된 TWDM PON (time and wavelength division multiplexed passive optical network)의 전력 절감형 동적 파장 및 대역할당 알고리즘의 성능을 평가한다. 성능평가에는 self-similar 트래픽을 사용하며 패킷의 평균시지연과 평균 상향 파장의 개수를 측정한다.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 동계학술발표회 논문집
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• pp.469-470
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.61-62
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• 2010

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.4-8
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• 2011

We have evaluated the performances of bidirectional optical amplifiers which were suited for the cost-effective implementation of amplified bidirectional passive optical networks (PONs). First, we measured the maximum gains of two simple bidirectional optical amplifiers implemented without using any optical components for the suppression of reflected signals. From the results, the maximum gains of two simple bidirectional amplifiers with a broadband light source (BLS) seeded optical source were limited to be 27 dB due to the reflection-induced in-band crosstalk, when the reflectance coefficients were measured to be -33 dB in both directions. Then, we have also implemented a bidirectional optical amplifier with two band splitters for the amplified bidirectional PON where the two different wavelength bands were allocated to the downstream and upstream signals transmission. In our measurement, we confirmed that the maximum gain of bidirectional optical amplifier with two band splitters could be increased to more than 30 dB owing to the efficient suppression of in-band crosstalk.

• Current Optics and Photonics
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• 제6권1호
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• pp.39-43
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• 2022

Underwater optical wireless communication (UOWC) is a good candidate for high-speed underwater wireless communication. In this work, we compare the performance of several modulation techniques for a UOWC system consisting of a light-emitting diode (LED) with an operating wavelength of 405 nm and a Si avalanche photodiode (APD). In this work, we consider six modulation schemes: 4-quadrature amplitude modulation (QAM), 8-QAM, quadrature phase shift keying (QPSK), binary phase shift keying (BPSK), on-off keying (OOK), and 4-pulse amplitude modulation (PAM). We also consider the cases of pure water and seawater for the working conditions. Our results show that 4-QAM and 8-QAM perform the best, in terms of communication distance and transmission power efficiency, for all water types considered.

• ETRI Journal
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• 제30권2호
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• pp.290-300
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• 2008

We apply IEEE 802.3 frame burst mode (FBM) to the Ethernet passive optical network (EPON) downstream link and compare its performance with non-frame burst mode for various traffic patterns. Although in light traffic loads (p<0.5) the efficiency of the FBM mechanism is not significant, it does feature high throughput, small jitter, low queue occupancy, and short queuing delay in optical line terminals under various traffic loads with various numbers of optical network units (ONUs). The FBM performance always approaches that of full-duplex mode, especially under heavy traffic loads (p>0.5). Moreover, an increase in number of ONUs will decrease the burst performance. Our work shows that FBM scheme is very useful for EPON transmission and has low design complexity.

• 한국정보과학회논문지:정보통신
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• 제36권4호
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• pp.360-368
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• 2009

세계적으로 가입자망의 고도화 및 광대역화가 경쟁적으로 추진되고, 이에 따른 신규 서비스도 활성화되고 있는 추세이다. 국내 광통신 산업의 저변 확대와 육성 발전, 차세대 장비 개발, 광가입자망 기반 고품질 서비스 및 플랫폼 개발의 일환으로, ETRI(Electronics and Telecommunications Research Institute)에서는 자체적으로 FTTH(Fiber-To-the-Home) 표준 BMT(Bench Mark Test) 테스트베드와 네트워크 운영센터 및 IPTV 서비스 장비로 FTTH 서비스센터를 구축하고, 통신망사업자를 통하여 규모 있는 상용 광가입자망을 구축하고 연동하였다. 본 논문에서는 ETRI의 FTTH 서비스센터와 통신사업자의 상용 광가입자망 구축에 사용되는 FTTH E-PON(Ethernet Passive Optical Network) 시스템에 대해 QoS(Qualiy of Service) 기반의 TPS(Triple Play Service)와 QoE(Quality of Experience) 측면에서 시험한 성능 평가 결과를 기술하였다.

• 정보저장시스템학회논문집
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• 제2권4호
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• pp.224-229
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• 2006

There has been studied flow to minimize the spot size to increase data capacity. Optical data storage devices are being developed near practical limits with wavelength and NA of 405nm and 0.85. There has been studied many types of next generation storage devices such as blu-ray multilayer system, probe based data storage and holographic data storage. Among these data storage devices, solid immersion lens(SIL) based near field recording (NFR) has been widely studied. In this system, SIL is the key component that focuses the laser beam with a very small size which enables ultra high data capacity. Therefore, optical performance evaluation system is required for SIL assembly. In this dissertation, a simple and accurate SIL assembly measurement method is proposed with wedge plate lateral shearing interferometer(LSI). Wedge plate LSI is cheaper than commercialized interferometer, robust to the vibration and the moving distance for phase shifting is large that is order of micrometer. We designed the thickness, wedge angle, material, surface quality and wavelength of wedge plate as 1mm, 0.02degree, fused silica, lamda/10(10-5) and 405nm, respectively. Also, we confirmed simulation and experimental results with quantitative analysis. This simple wedge plate LSI can be applied to different types of SIL such as solid immersion mirror(SIM), hemispherical, super-hemispherical and elliptical SIL.

• 한국태양에너지학회 논문집
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• 제31권1호
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• pp.31-36
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• 2011

CF(Circular Fresnel) POF(Plastic Optical Fiber) daylighting system is a beam daylighting system utilizing solar direct beam radiation. In this study, a CF POF daylighting system has been introduced, developed and applied to KIER test buildings. The CF POF daylighting system consists of three parts: light collector, light transmitter and light diffuser. The light collector includes a Circular Fresnel lens focusing solar direct illuminance by sun tracking. The light transmitter contains the POF cable which has light transmission loss of 4.5% per meter. The light diffuser has about 80% diffuser efficiency. This study aims to evaluate of POF daylighting system performance. At the results of a CFPOF system performance evaluation, the theoretical CFPOF system efficiency was 41.9% and the actual CFPOF system efficiency at the KIER test building was 37.5%. The difference was due partly to the connecting efficiency.

• 소성∙가공
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• 제11권7호
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• pp.589-595
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• 2002

Up to now, Collimators have been generally produced by handwork and only a few companies have produced by semi-automatic system. Under this situation, automatic system for assembly of optical collimator has risen as a most essential technique in the development of optical communication components. In this study, it was constructed to develop optical collimators with high functionality and We manufactured optical collimators with a GRIN rod lens using automatic system. Therefore, we worked a performance test through a comparison of collimators made by automatic system and handwork with angle alignment, beam size. Also we compared common product with auto-manufactured sample. As a result, it brought a reduction of the tact time and an improvement of an efficiency and a productivity of optical collimators. therefore it was found that automatic system was indispensable for materialization of optical collimators with high functionality.