• Title/Summary/Keyword: 유효광도

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Effective Net Residual Dispersion Depending on Total Transmission Length in Optical Transmission Links with a Randomly Distributed RDPS (RDPS가 랜덤하게 분포하는 분산 제어 광전송 링크에서 전체 전송 거리에 따른 유효 전체 잉여 분산)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.17 no.4
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    • pp.413-420
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    • 2013
  • The design rule depending on total transmission length is induced in the optical links with residual dispersion per span (RDPS) of the random distribution, which is adopted for implementing the flexible systems of wavelength division multiplexing (WDM) transmission with dispersion management (DM) and optical phase conjugation. DM parameters used for the analysis of the design rule are the effective net residual dispersion (NRD) and the effective launch power. It is confirmed that the flexible optical network configuration with the total transmission length lower than 1,000 km is possible, because the system performance difference between the randomly distribution and the uniform distribution of RDPS is small. And, in the optical links with the randomly distributed RDPS, the wide NRD can be applied for transmitting WDM channels of the relatively wide launch power.

Transmission Distance Depending on Transmission Capacityin Inline Dispersion Managed WDM Systems (Inline 분산 제어가 적용된 WDM 시스템에서 전송 용량에 따른 전송 거리)

  • Lee, Seong-Real;Cho, Sung-Eon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.5
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    • pp.959-966
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    • 2009
  • Effective transmission distance depending on transmission capacity of WDM systems with inline dispersion management (DM) and optical phase conjugator (OPC) at middle of total transmission length is investigated. The range of net residual dispersion (NRD) resulting 1 dB eye opening penalty (EOP) in 1 Tbps WDM system, in which NRD controlled by only postcompensation, is also investigated. It is confirmed that effective transmission distances are increasedto longer than several hundreds kilometers by applying optimal NRD depending on transmission capacity and distance. And it is confirmed that in 1 Tbps WDM system if NRD is determined to +17 ps/nm, the maximum transmission distance is achieved, and, especially, in long-haul 1 Tbps WDM system the effective NRD range will be determined within positive value.

The interface effects on polarization dependence of waveguide and the design of polarization independent 2 dimensional waveguide on InP for arrayed waveguide grating (도파로의 편광 의존성에 경계면이 미치는 효과와 편광 독립적인 InP형 배열 도파로 회절 격자 소자를 위한 2차원 광 도파로의 설계)

  • 김동철;최정훈;유건호;김형문;주흥로;김홍만
    • Korean Journal of Optics and Photonics
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    • v.9 no.5
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    • pp.307-314
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    • 1998
  • We have studied the effects of interface on polarization dependence of waveguide and designed the polarization independent 2-dimensional waveguides on InP for arrayed waveguide grating. To figure out the effects of interface on polarization dependence, we have solved the 1-dimensional wave equation using a transfer matrix method. It is shown that the birefringence becomes stronger as the number of interfaces increases. In order to design polarization independent 2-dimensional waveguides, we have used effective index method. The structures considered are ridge type, raised strip type, and buried type waveguide. In the cases of ridge and raised strip type, conventional effective index method was used. In the case of buried type corrected effective index method was used. We have determined the height and width of waveguides such that the waveguides become polarization independent.

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Quantitative Dispersion Evaluation of Carbon Nanotubes Reinforced Polymer Nano-composites (탄소나노튜브 첨가 고분자 나노복합재료의 정량적 분산도 평가)

  • Lee, Sang-Bok;Jeong, Bo-Hwa;Yi, Jin-Woo;Lee, Won-Oh;Um, Moon-Kwang
    • Polymer(Korea)
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    • v.35 no.1
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    • pp.60-65
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    • 2011
  • In order to maximize the performance of polymer nano-composites, it is essential to understand an effect of a dispersion state on material properties as well as to achieve highly dispersed composites. In this work, a simple quantitative approach to evaluate the degree of dispersion was suggested for carbon nanotube (CNT) embedded polymer nano-composites. Through UV-visible spectroscopy analysis, the transmittance of nano-composites was measured at various dispersion states and it was found that the transmittance reduced as the dispersion state of CNT improved. Based on the results, an effective concentration factor for quantitative evaluation of dispersion state was introduced into the Beer-Lambert transmittance law. The proposed method and parameter to evaluate the degree of dispersion were verified by analyzing the transmittances at different dispersion states of CNT, concentrations of CNT and sample thicknesses.

Vicarious Radiometric Calibration of the Ground-based Hyperspectral Camera Image (지상 초분광카메라 영상의 복사보정)

  • Shin, Jung-Il;Maghsoudi, Yasser;Kim, Sun-Hwa;Kang, Sung-Jin;Lee, Kyu-Sung
    • Korean Journal of Remote Sensing
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    • v.24 no.2
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    • pp.213-222
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    • 2008
  • Although hyperspectral sensing data have shown great potential to derive various surface information that is not usually available from conventional multispectral image, the acquisition of proper hyperspectral image data are often limited. To use ground-based hyperspectral camera image for remote sensing studies, radiometric calibration should be prerequisite. The objective of this study is to develop radiometric calibration procedure to convert image digital number (DN) value to surface reflectance for the 120 bands ground-based hyperspectral camera. Hyperspectral image and spectral measurements were simultaneously obtained from the experimental target that includes 22 different surface materials of diverse spectral characteristics at wavelength range between 400 to 900 nm. Calibration coefficients to convert image DN value to at-sensor radiance were initially derived from the regression equations between the sample image and spectral measurements using ASD spectroradiometer. Assuming that there is no atmospheric effects when the image acquisition and spectral measurements were made at very close distance in ground, we were also able to derive calibration coefficients that directly transform DN value to surface reflectance. However, these coefficients for deriving reflectance values should not be applied when the camera is used for aerial image that contains significant effect from atmosphere and further atmospheric correction procedure is required in such case.

Effectiveness of Beam-propagation-method Simulations for the Directional Coupling of Guided Modes Evaluated by Fabricating Silica Optical-waveguide Devices (광도파로 모드 간의 방향성 결합현상에 대한 빔 진행 기법 설계의 효율성 및 실리카 광도파로 소자 제작을 통한 평가)

  • Jin, Jinung;Chun, Kwon-Wook;Lee, Eun-Su;Oh, Min-Cheol
    • Korean Journal of Optics and Photonics
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    • v.33 no.4
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    • pp.137-145
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    • 2022
  • A directional coupler device, one of the fundamental components of photonic integrated circuits, distributes optical power by evanescent field coupling between two adjacent optical waveguides. In this paper, the design process for manufacturing a directional coupler device is reviewed, and the accuracy of the design results, as seen from the characteristics of the actual fabricated device, is confirmed. When designing a directional coupler device through a two-dimensional (2D) beam-propagation-method (BPM) simulation, an optical structure is converted to a two-dimensional planar structure through the effective index method. After fabricating the directional coupler device array, the characteristics are measured. To supplement the 2D-BPM results that are different from the experimental results, a 3D-BPM simulation is performed. Although 3D-BPM simulation requires more computational resources, the simulation result is closer to the experimental results. Furthermore, the waveguide core refractive index used in 3D-BPM is adjusted to produce a simulation result consistent with the experimental results. The proposed design procedure enables accurate design of directional coupler devices, predicting the experimental results based on 3D-BPM.

Experimental Investigation of Concentrating Photovoltaic System Applying Commercial Multi-array Lens for Space Applications (상용 배열형 렌즈를 적용한 집광형 태양전력시스템의 우주 적용 가능성 실험적 검토)

  • Park, Tae-Yong;Chae, Bong-Geon;Lee, Yong-Geun;Kang, Suk-Joo;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.7
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    • pp.622-627
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    • 2014
  • A pico-class satellite has limitation to generate power from the solar cells due to its limited accommodation area to install the solar cells. The variation of incidence angle between solar panels and sunlight induced by the revolution and rotation of the satellite is one of the key parameters to determine the power generation. In this study, we proposed a concentrating photovoltaic system for pico-class satellite applications to enhance power generation when the ${\beta}$ angle between the sunlight and the solar panel is zero by effectively concentrating solar energy on solar panels. The feasibility of the conceptual idea has been demonstrated by power measurement test using solar simulator and commercial multi-array lens system.

국내 석회석의 활용현황

  • 채영배;정수복;김완태
    • Proceedings of the Mineralogical Society of Korea Conference
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    • 2002.10a
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    • pp.93-101
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    • 2002
  • 석회석은 우리나라 광업법 제3조에서 규정한 법정광물로써 백운석, 대리석, 방해석 및 코퀴나 등을 포함하며, 최근 우리나라 전체 광산물 생산량의 $75\%$를 상회하는 단일광종 최대생산량을 나타내고 있는 광종이다. 이외에도 석회석 광은 여러 가지 통계적으로도 국내 최대임을 나타내는데, 즉, 2001년도 우리나라 일반광(66종) 등록광구수 5,242개소 중에서 1,494개소를 차지하여 $28.5\%$를 차지하며, 가행광산 수에서도 320개소 중 109개소$(34\%)$, 근로자 수에서는 4,291명중에서 2,748명$(64\%)$으로 최대의 규모를 가지고 있다. 실제로 석회석 및 관련제품은 오늘날 화학공업이나 환경산업 등 각종의 산업에 널리 이용되고 있으며, 그의 이용 역사에서도 유구한 역사를 가지고 있다. 즉, 고대 유적분석 결과는 이미 신석기 시대에도 석회 재료가 쓰였을 것으로 보고되고 있으며, 성경(신명기 27장 1-5절)에도 소개되고 있고, 우리나라에서의 석회 사용의 역사도 동국여지승람(성종16년), 세종실록, 문종실록 등에 석회 산지가 자세히 조사 기록되어 있으며 소성석회의 제조, 사용에 대하여도 기록하고 있다. 이외에도, 그리이스, 로마, 중국 등지의 역사에서는 건축재, 농업, 표백 및 제혁공업 등에 사용되었다는 사실이 발견되고 있지만, 석회석의 용도가 크게 증가된 것은 역시 산업혁명 이후 20세기가 시작되면서부터 라고 할 수 있다. 석회석은 국가산업구조 및 인간의 삶의 양식에 따라 그의 용도가 다양하고, 광범위하게 변화하는 만큼, 그의 품질 또한 중요하게 취급되어야 하지만, 우리나라의 경우에는 아직도 시장규모가 큰 일부용도이외에 사용자의 요구에 부합되는 다양한 품질의 석회제품을 제조하는 데에는 인색하고, 또한 사용자의 대부분은 용도가 명시되어 있는 외국의 제품을 선호하는 경향에 따라 석회석 및 관련제품의 수입량이 감소하지 않고 있다. 최근 우리나라는 국제통화기금(IMF)이후에, 국내산업을 보호하는 정부의 규제나 지원은 폐지 또는 축소되고, 외국회사의 시장참여에 의한 국제경쟁기반이 약화되고 있는 것도 사실이지만, 고 환율에 의하여 일부제품의 수입은 자제되고, 국내산 대체 방향으로 진행되고 있기 때문에, 안정되고 신뢰할 수 있는 품질의 제품을 제조하는 경우에는 오히려 국내시장의 확장에는 좋은 시기가 될 수도 있다고 판단된다. 이에 본고에서는 최근 국내 석회석 관련제품을 활용하는 사례를 분석하고 향후 유효 이용을 도모하는 데에 참고가 되었으면 하는 마음에서 작성하였다.

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Improvement of the Signal-to-Noise Ratio of Photorefractive Joint Transform Correlator using Characteristics of $BaTiO_3$ ($BaTiO_3$의 특성을 이용한 광굴절 결합 변환 상관기의 신호 대 잡음비 개선)

  • 공명술;서동환;신창목;조규보;김철수;김수중
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.3
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    • pp.19-32
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    • 2003
  • In the conventional photorefractive joint transform correlator(PRJTC), the intensity ration of input signal-to-pump beam should be large enough to saturate two-beam coupling transfer function to obtain a desired correlation result. As a result, the signal-to-noise ratio(SNR) of correlation result is decreased in a noisy input image. In this paper, we propose the improved method for increasing the SNR of the PRJTC by using the characteristics of BaTiO$_3$. We stop the energy transfer saturating by low intensity ratio of input beam and realize a short length of effective interaction in BaTiO$_3$ by making large incident angle of the signal beam. So the gain in high frequency area is decreased and the gain in low frequency area comes up to the saturation gain of the beam coupling transfer function. Therefore the SNR is improved in noisy input image and the PRJTC can be easily realized by low intensity ratio of input beam.

Cross Phase Modulation Effects on 120 Gbps WDM Transmission Systems with Mid-Span Spectral Inversion for Compensation of Distorted Optical Pulse (광 펄스 왜곡의 보상을 위해 Mid-Span Spectral Inversion 기법을 채택한 120 Gbps WDM 시스템에서 채널간 상호 위상 변조 현상의 영향)

  • 이성렬;권순녀;이윤현
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.7
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    • pp.741-749
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    • 2003
  • In this paper, we investigated the degree of compensation for WDM channel signal distortion due to chromatic dispersion, self phase modulation(SPM) and cross phase modulation(XPM). The considered system is 120 Gbps (3${\times}$40 Gbps) intensity modulation direct detection(IM/DD) WDM transmission system with path-averaged intensity approximation(PAIA) mid-span spectral inversion(MSSI) as compensation method. This system have highly nonlinear dispersion shifted fiber(HNL-DSF) as nonlinear medium in optical phase conjugator(OPC). We use 1 dB eye opening peralty(EOP) in order to evaluate the characteristics of compensation for distorted WDM channels. We confirmed that improvement of transmission distance and performance is achieved by MSSI method to distorted long-haul IM/DD WDM channels due to chromatic dispersion, SPM and XPM. And in the aspect of compensation for distorted pulse due to XPM, the MSSI method is effective to IM/DD WDM transmission system with high fiber dispersion coefficient.