• Title, Summary, Keyword: Reflectivity

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Daylighting Performance Evaluation of Light-shelf according to the Reflectivity - Focused on the Residing space - (반사율에 따른 광선반 채광 성능평가 연구 - 주거공간을 중심으로 -)

  • Heo, Doyeon;Lee, Heangwoo;Seo, Janghoo;Kim, Yongseong
    • KIEAE Journal
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    • v.15 no.3
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    • pp.49-56
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    • 2015
  • Purpose: Due to recent increase on energy consumption for light in building, many studies to mitigate this issue have been conducted. Various researches have been carried out to suggest light shelf as one of the solutions, but researches for its reflectivity is very few. In fact, existing research on light shelf shows that utilizing more than 90% of high-illumination materials causes imbalance of glare and illuminance. Method: Therefore this research aimed to evaluate the performance of light shelves depending on reflectivity and to identify proper solution through test-bed. Result: The results are following: 1) Increased reflectivity generally contributed to increase of indoor illuminance but degrade uniformity factor related with indoor comfort of light environment. 2) The $0^{\circ}fixed$ light shelf with 75% of reflectivity and width of 300mm and 40mm appeared to consume more energy than other shelves. Therefore, it is analyzed as unsuitable. 3) This research was conducted by calculating appropriate angle of light shelf around winter and summer solstices and vernal/autumnal equinox. Based on this, performance evaluation was undertaken depending on reflectivity of movable light shelf, which is activated by external sources and can be applied with lower reflectivity than fixed shelf. However, one exception was a movable shelf with width of 600mm that increased light energy consumption when 75% of reflectivity was applied. 4) Performance evaluation of fixed and movable light shelf showed that the shelf with 80% of reflectivity came up with suitable results, but 75% of reflectivity may be applied depending on the width and angle of the shelf. This research is meaningful in that estimation of appropriate reflectivity of light shelf can resolve the glare problem and improve light environment, and further research would be desirable under more diverse conditions to identify proper solution.

3D Radar Objects Tracking and Reflectivity Profiling

  • Kim, Yong Hyun;Lee, Hansoo;Kim, Sungshin
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.12 no.4
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    • pp.263-269
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    • 2012
  • The ability to characterize feature objects from radar readings is often limited by simply looking at their still frame reflectivity, differential reflectivity and differential phase data. In many cases, time-series study of these objects' reflectivity profile is required to properly characterize features objects of interest. This paper introduces a novel technique to automatically track multiple 3D radar structures in C,S-band in real-time using Doppler radar and profile their characteristic reflectivity distribution in time series. The extraction of reflectivity profile from different radar cluster structures is done in three stages: 1. static frame (zone-linkage) clustering, 2. dynamic frame (evolution-linkage) clustering and 3. characterization of clusters through time series profile of reflectivity distribution. The two clustering schemes proposed here are applied on composite multi-layers CAPPI (Constant Altitude Plan Position Indicator) radar data which covers altitude range of 0.25 to 10 km and an area spanning over hundreds of thousands $km^2$. Discrete numerical simulations show the validity of the proposed technique and that fast and accurate profiling of time series reflectivity distribution for deformable 3D radar structures is achievable.

X-Ray Reflectivity Analysis Incorporated with Genetic Algorithm to Analyze the Y- to X Type Transition in CdA LB Film

  • 최정우;조경상;이희우;이원홍;이한섭
    • Bulletin of the Korean Chemical Society
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    • v.19 no.5
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    • pp.549-553
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    • 1998
  • The structure and layer distribution of cadmium arachidate Langmuir-Blodgett film were analyzed by the small angle X-ray reflectivity measurements using synchrotron radiation. Y-to X type transition was ocurred during the 39th passage of deposition of cadmium arachidate. Based on the measurement of the consumed area of the monolayer, it was determined that about 27.5 layer was deposited. Using the synchrotron X-ray, the reflectivity profile of cadmium arachidate LB film over the wide range of grazing angle was obtained. The X-ray reflectivity profile was analyzed using the recursion formula. By fitting the location and dispersion of the subsidiary maxima between the Bragg peaks of the measured reflectivity profile with that of the calculated reflectivity profile, the average thickness and the distribution of layer thickness were evaluated. The genetic algorithm was adopted to the fitting of reflectivity profile to evaluate the optimum value of the number distribution of layer. Based on the morphology measurement with an atomic force microscopy (AFM), the domain structure and mean roughness of LB films were obtained. The mean roughness value calculated based on the number of layer distribution obtained from the measurement by AFM is consistent with that obtained from X-ray reflectivity analysis.

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The Effect of Front Facet Reflections on the Reflectivity Spectrum of Bragg Reflector structures (단면 반사율이 Bragg Reflector 구조의 전체 반사율 스펙트럼에 미치는 효과)

  • 김부근
    • Proceedings of the Optical Society of Korea Conference
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    • pp.203-208
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    • 1991
  • We present an analytic equation for the reflectivity spectrum of a Bragg reflector in terms of the front mirror reflectivity, due to the refractive index difference between the refractive index of outside medium and the average refractive index of Bragg reflector structures, and the reflectivity of a Bragg reflector calculated by the coupled wave method. We show that even Fresnel reflection causes the reflectivity spectrum of a bragg reflector to be very different from that of Bragg reflectors calculated by the coupled wave method. The reflectivity spectrum of a Bragg reflector is dramatically changed because the interference effect between the reflected wave from the front facet and that from the Bragg reflector is changed due to the difference of a phase change from a Bragg reflector when the sequence of layers in a Bragg reflector is changed.

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Preparation and Characterization of Porous Polymethylmethacrylate Film Showing Optical Reflectivity

  • Kim, Jihoon
    • Journal of the Chosun Natural Science
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    • v.6 no.2
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    • pp.82-86
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    • 2013
  • This paper describes a method for the preparation of porous polymethylmethacrylate showing optical reflectivity from the porous silicon template. A porous polymethylmethacrylate showing optical reflectivity was prepared by replicating porous silicon template which was obtained by applying a computer-generated periodic square current density and resulted in a mirror with high reflectivity in a specific narrow spectral region. A porous polymethylmethacrylate showing an excellent reflectivity was successfully obtained by dissolving the Porous silicon template from the porous polymethylmethacrylate composite film. A porous polymethylmethacrylate exhibited a sharp reflection resonance in the reflectivity spectrum. Surface image of the porous polymethylmethacrylate indicated that the surface of the porous polymethylmethacrylate film had a porous structure. These porous polymethylmethacrylate films in aqueous solutions were stable for several days without any degradation.

Analysis of Generating Efficiency in PV Window System consequent on Apartment House Wall Reflectivity (공동주택 벽체 반사율에 따른 PV창호시스템 발전효율 분석)

  • Choi, Doo-Sung;An, Jun-Ho;Jeon, Hung-Chan;Do, Jin-Seok
    • Journal of the Korean Solar Energy Society
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    • v.36 no.2
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    • pp.31-39
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    • 2016
  • This study did quantitative comparative evaluation of changes in generation consequent on reflectivity of the protruding wall near the widow in case of application of PV window system to an apartment house. To be concrete, this study did comparative analysis of the generation of (B) through the process of composing Mock-up (A)comprising the protruding window near the window and Mock-up(B) free of nearby wall interference, and giving change to the reflectivity of the wall (Case_1~3). The analysis result showed that the difference in generation was slight in case solar radiation was less than 10,000Wh in all three conditions. On the contrary, in case solar radiation was more than 10,000 Wh, the generation as against Module(B), was analyzed to be 87~91% in Case_1(5% reflectivity), 18~60% in Case_2(85% reflectivity), and 16~71% in case_3(93% reflectivity), respectively.

Calculation of Reflectivity for W/Si Multilayer Mirror of Small d-Spacing (작은 두께주기를 갖는 W/Si 다층박막거울의 반사율 계산)

  • Chon, Kwon Su
    • Journal of the Korean Society of Radiology
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    • v.12 no.1
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    • pp.17-22
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    • 2018
  • Multilayer mirrors are optical elements that can replace single crystal optical elements such as silicon or germanium, and they have artificial diffraction plane of a thickness of several nanometers. We examined the first Bragg angle and the reduction of reflectivity by variation of layer thickness in a W/Si multilayer mirror of small d-spacing. A W/Si multilayer mirror for an incidence angle of $0.55^{\circ}$ and an energy of 17.5 keV was designed and showed a maximum reflectivity of 72.67%. When the thickness of tungsten or silicon layer was simultaneously changed, the first Bragg angle was shifted and the reflectivity was reduced. When there was a change in thickness for one layer of W/Si multilayer, no change in the reflectivity was showed but the unevenness of the envelope was observed. Reduction of reflectivity was also observed at random Gaussian thickness variations. It is possible to predict the tolerance of multilayer mirror by examining the reflectivity degradation according to the thickness change in the W/Si multilayer mirror of small d-spacing.

Analysis of Reflectivity for Interfacial Roughness of Depth-Graded W/Si Multilayer Mirror (두께 변화 W/Si 다층박막거울의 계면 거칠기에 대한 반사율 분석)

  • Chon, Kwon Su
    • Journal of the Korean Society of Radiology
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    • v.12 no.1
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    • pp.101-106
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    • 2018
  • Multilayer mirrors have widely been used for monochromatization of X-ray with high reflection efficiency. The reflected X-ray energy or wavelength is determined by the d-spacing of a multilayer mirror and the incidence angle. The reflectivity critically depends on the number of bilayers and surface roughness on each interface. The multilayer mirror has a structure of alternative deposition of high and low Z-elements on the substrate. Each interface should be considered in the calculation of reflectivity. In this paper, we examine the degradation of reflectivity by the inter-diffusion combined with surface roughness on each interface for a W/Si multilayer mirror. In the depth-graded W/Si multilayer mirror, the FWHMs for angle and energy were larger than them of the uniform multilayer mirror. Inter-diffusion considerable gave rise to the degradation of reflectivity. To obtain measured reflectivity closed to the expected reflectivity, the inter-diffusion on W-Si and Si-W interfaces should be considered.

Reflectivity Mosaic of Two Radars Using a Height-weighted Method (고도 가중 방법을 이용한 레이더 반사도의 합성)

  • Lee, Jung-Hoon;Jung, Sung-Hwa;Heo, Bok-Haeng;Kim, Kyung-Eak
    • Korean Journal of Remote Sensing
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    • v.26 no.4
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    • pp.373-385
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    • 2010
  • A new method to mosaic reflectivity over the overlapped coverage of two radars was developed. The method mosaics the radar reflectivity with weights after adjustment of reflectivity differences on overlapped coverage of neighboring two radars. Their weights are inverse proportion to the difference between the height of an interpolated reflectivity and the level of CAPPI (Constant Altitude PPI). The performance of this method was compared to different mosaic methods (Mosaics by maximum value, averaged value, nearest value and distance weighted value) using the reflectivity fields of a typhoon event observed by two radar. New method was better than any other methods either as a continuity and as a bias analysis of reflectivity at the boundaries in overlapped coverage by two radars.

3D LIDAR Based Vehicle Localization Using Synthetic Reflectivity Map for Road and Wall in Tunnel

  • Im, Jun-Hyuck;Im, Sung-Hyuck;Song, Jong-Hwa;Jee, Gyu-In
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.4
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    • pp.159-166
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    • 2017
  • The position of autonomous driving vehicle is basically acquired through the global positioning system (GPS). However, GPS signals cannot be received in tunnels. Due to this limitation, localization of autonomous driving vehicles can be made through sensors mounted on them. In particular, a 3D Light Detection and Ranging (LIDAR) system is used for longitudinal position error correction. Few feature points and structures that can be used for localization of vehicles are available in tunnels. Since lanes in the road are normally marked by solid line, it cannot be used to recognize a longitudinal position. In addition, only a small number of structures that are separated from the tunnel walls such as sign boards or jet fans are available. Thus, it is necessary to extract usable information from tunnels to recognize a longitudinal position. In this paper, fire hydrants and evacuation guide lights attached at both sides of tunnel walls were used to recognize a longitudinal position. These structures have highly distinctive reflectivity from the surrounding walls, which can be distinguished using LIDAR reflectivity data. Furthermore, reflectivity information of tunnel walls was fused with the road surface reflectivity map to generate a synthetic reflectivity map. When the synthetic reflectivity map was used, localization of vehicles was able through correlation matching with the local maps generated from the current LIDAR data. The experiments were conducted at an expressway including Maseong Tunnel (approximately 1.5 km long). The experiment results showed that the root mean square (RMS) position errors in lateral and longitudinal directions were 0.19 m and 0.35 m, respectively, exhibiting precise localization accuracy.