• Title/Summary/Keyword: Light propagation

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Spatio-Angular Consistent Edit Propagation for 4D Light Field Image (4 차원 Light Field 영상에서의 일관된 각도-공간적 편집 전파)

  • Williem, Williem;Park, In Kyu
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2015.11a
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    • pp.180-181
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    • 2015
  • In this paper, we present a consistent and efficient edit propagation method that is applied for light field data. Unlike conventional sparse edit propagation, the coherency between light field sub-aperture images is fully considered by utilizing light field consistency in the optimization framework. Instead of directly solving the optimization function on all light field sub-aperture images, the proposed optimization framework performs sparse edit propagation in the extended focus image domain. The extended focus image is the representative image that contains implicit depth information and the well-focused region of all sub-aperture images. The edit results in the extended focus image are then propagated back to each light field sub-aperture image. Experimental results on test images captured by a Lytro off-the-shelf light field camera confirm that the proposed method provides robust and consistent results of edited light field sub-aperture images.

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Application of Light Collecting Probe with High Spatial Resolution to Spark-Ignited Spherical Spray Flames

  • Yang, Young-Joon;Akamatsu, Fumiteru;Katsuki, Masashi
    • Journal of Mechanical Science and Technology
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    • v.18 no.11
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    • pp.2058-2065
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    • 2004
  • A light collecting probe named Multi-color Integrated Cassegrain Receiving Optics (MICRO) is applied to spark-ignited spherical spray flames to obtain the flame propagation speed in freely falling droplet suspension produced by an ultrasonic atomizer. Two MICRO probes are used to monitor time-series signals of OH chemiluminescence from two different locations in the flame. By detecting the arrival time difference of the propagating flame front, the flame propagation speed is calculated with a two-point delay-time method. In addition, time-series images of OH chemiluminescence are simultaneously obtained by a high-speed digital CCD camera to ensure the validity of the two-point delay-time method by the MICRO system. Furthermore, the relationship between the spray properties measured by phase Doppler anemometer (PDA) and the flame propagation speed are discussed with three different experimental conditions by changing the fuel injection rate. It was confirmed that the two-point delay-time method with two MICRO probes is useful and convenient to obtain the flame propagation speed and that the flame propagation speed depends on the spray properties.

Application of Light Collecting Probe with High Spatial Resolution to Spark-Ignited Spherical Spray Flames (불꽃점화 구형분무화염에서 고공간 분해능을 가진 집광프로브의 응용)

  • Yang Young-Joon
    • Journal of the Korean Society of Safety
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    • v.19 no.3 s.67
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    • pp.20-25
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    • 2004
  • In order to obtain the flame Propagation speed in freely falling droplet suspension Produced by an ultrasonic atomizer, a light collecting probe named Multi-color Integrated Cassegrain Receiving Optics (MICRO) is applied to spark-ignited spherical spray flames. Two MICRO probes are used to monitor time-series signals of OH chemilumine-scence from two different locations in the flame. The flame propagation speed is calculated by detecting the arrival time difference of the propagating flame front. In addition, time-series images of OH chemiluminescence are simultaneously obtained by a high-speed digital CCD camera to ensure the validity of the MICRO system. Furthermore, relationship between the spray properties measured by phase Doppler anemometer (PDA) and the flame propagation speed are discussed with k different experimental conditions by changing the fuel injection rate. It was confirmed that the MICRO probe system was very useful and convenient to obtain the flame propagation speed and that the flame propagation speed was different depending on the spray properties.

Light Propagation in a Strained and Heated Crystal (변형 및 온도 변화 존재시 단결정에서의 빛의 거동)

  • 조동원;김기수
    • Korean Journal of Crystallography
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    • v.5 no.1
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    • pp.7-13
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    • 1994
  • Light propagation in an anisotropic crystal in the presence of strains and temperature change is investigated. This phenomenon appears in an embedded optical films sensor inside the structure or in an optical on the substrate for optical devices. The refractive indices which represent the light propagation in an anisotopic crystal are calculated and the changes of these refractive indices in the presence of strains and tepmerature change are also calculated. The calculations for the light propagation. In an isotropic medium with the simplified model are performed and the results are compared with devious investigators.

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Near-Infrared Light Propagation in an Adult Head Model with Refractive Index Mismatch

  • Kim, Seung-Hwan;Lee, Jae-Hoon
    • ETRI Journal
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    • v.27 no.4
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    • pp.377-384
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    • 2005
  • We investigate near-infrared light (NIR) propagation in a model of an adult head using an extensive Monte Carlo (MC) simulation. The adult head model is a four-layered slab which consists of a surface layer, a cerebrospinal fluid layer, a gray-matter layer, and a white-matter layer. We study the effects of a refractive index mismatch on the model, calculating the intensity of detected light, mean flight time, and partial mean flight time of each layer for various refractive indices of the cerebrospinal fluid layer as functions of source-detector spacing. The Monte Carlo simulation shows that the refractive index mismatch presents very rich results including rapidly decaying intensity of detected light and a peak and cross-over in the partial mean flight time with source-detector spacing. We also investigate spatial sensitivity profiles at various source-detector spacings, discussing the index mismatch effect on the model.

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Visible Wavelength Photonic Insulator for Enhancing LED Light Emission

  • Ryoo, Kwangki;Lee, Jeong Bong
    • Journal of information and communication convergence engineering
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    • v.13 no.1
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    • pp.50-55
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    • 2015
  • We report design and simulation of a two-dimensional (2D) silicon-based nanophotonic crystal as an optical insulator to enhance the light emission efficiency of light-emitting diodes (LEDs). The device was designed in a manner that a triangular array silicon photonic crystal light insulator has a square trench in the middle where LED can be placed. By varying the normalized radius in the range of 0.3-0.5 using plane wave expansion method (PWEM), we found that the normalized radius of 0.45 creates a large band gap for transverse electric (TE) polarization. Subsequently a series of light propagation simulation were carried out using 2D and three-dimensional (3D) finite-difference time-domain (FDTD). The designed silicon-based light insulator device shows optical characteristics of a region in which light propagation was forbidden in the horizontal plane for TE light with most of the visible light spectrum in the wavelength range of 450 nm to 600 nm.

Exploration on possibility of finding gifted underachievers with high spatial ability and low verbal ability in elementary science field: Focused on "Light Propagation" (높은 공간능력과 낮은 언어능력을 가진 초등 미성취 과학영재의 발견가능성 탐색 - 빛의 직진 개념을 중심으로 -)

  • Jung, Yeon-su;Lee, Jiwon;Kim, Jung Bog
    • Journal of Gifted/Talented Education
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    • v.26 no.1
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    • pp.101-122
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    • 2016
  • The purpose of this study is to explore a possibility finding gifted underachievers who have high spatial ability, but low verbal ability in elementary science field. In Korea, because teachers used to refer students' academic achievement only when they recommend gifted students, underachievers used to be excluded. The participants are 5th-grade students in elementary school. In this research, developed teaching materials were given to students to find underachievers. Results of spatial ability test, verbal ability test, science academic achievement, non-verbal test, and interviews about light propagation concept were obtained. By analyzing results of this study, we found that spatial ability is the most important factors to understand light propagation. And there are some features to understand light propagation according to spatial ability. Lastly, this study shows the possibility of non-verbal test to find gifted underachievers with high spatial ability and low verbal ability.

Observation of Light-Propagation along the Tube of Cold Cathode Fluorescent Lamp (냉음극 형광램프의 광 전파)

  • Cho, Y.H.;Jin, D.J.;Kim, J.H.;Han, S.H.;Cho, G.S.
    • Journal of the Korean Vacuum Society
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    • v.20 no.2
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    • pp.114-126
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    • 2011
  • The light propagation along a long positive column has been observed in a cold cathode fluorescent lamp. The optical signals are observed with the DC and AC voltage power during lamp operation. The light propagating is observed in the operation with the DC-rippled voltage as well as the AC-voltage. The optical signals propagate from the high voltage side to the ground. These signals show two kinds of features according to the before and after Townsend breakdown. At the dark current before Townsend breakdown, the optical intensity is damped and the propagation velocity is $10^4{\sim}10^5m/s$. At the high current of normal glow after Townsend breakdown, the propagation velocity is 1$10^5{\sim}10^6m/s$ without damping.

Study of Propagation of Light along an Acupuncture Meridian

  • Choi, Chun-Ho;Soh, Kwang-Sup;Lee, Sang-Min;Yoon Gil-Won
    • Journal of the Optical Society of Korea
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    • v.7 no.4
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    • pp.245-248
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    • 2003
  • Propagation of light along a pericardium meridian is measured and compared with that along a non-meridian path one cm away from the meridian. Source-light is illuminated on the Nei-Guan(PC6) and propagated light is detected at three points along the meridian. Four reference points are one cm away from the corresponding meridian points, respectively. Light propagates better along the meridian than the reference path with more than twenty percent difference for all the subjects tested.

Deep Learning: High-quality Imaging through Multicore Fiber

  • Wu, Liqing;Zhao, Jun;Zhang, Minghai;Zhang, Yanzhu;Wang, Xiaoyan;Chen, Ziyang;Pu, Jixiong
    • Current Optics and Photonics
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    • v.4 no.4
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    • pp.286-292
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    • 2020
  • Imaging through multicore fiber (MCF) is of great significance in the biomedical domain. Although several techniques have been developed to image an object from a signal passing through MCF, these methods are strongly dependent on the surroundings, such as vibration and the temperature fluctuation of the fiber's environment. In this paper, we apply a new, strong technique called deep learning to reconstruct the phase image through a MCF in which each core is multimode. To evaluate the network, we employ the binary cross-entropy as the loss function of a convolutional neural network (CNN) with improved U-net structure. The high-quality reconstruction of input objects upon spatial light modulation (SLM) can be realized from the speckle patterns of intensity that contain the information about the objects. Moreover, we study the effect of MCF length on image recovery. It is shown that the shorter the fiber, the better the imaging quality. Based on our findings, MCF may have applications in fields such as endoscopic imaging and optical communication.