• Title/Summary/Keyword: Interference Image

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The Rejection of the GPS Interference Mirror Image by using the Three-dimensional Array Antenna (3차원 구조 배열안테나를 적용한 GPS 간섭신호 미러 이미지 제거)

  • Kim, JunO;Lee, Sang Jeong
    • Journal of Advanced Navigation Technology
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    • v.22 no.4
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    • pp.295-301
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    • 2018
  • Recently, GPS(Global Positioning System) array antenna technology is generally used and widely adopted as a national infrastructure structure and aero-vehicles for protection the GPS signal reception. Until now, the 2-dimensional planar array is universally used for its applications in the array antenna signal processing, however relatively higher altitude air vehicles such as UAV experiences additional null zones induced by low altitude GPS interferences which is located in a symmetry zone of antenna horizontal plane and this could make the receiving antenna pattern coverage reduction. In this paper, we improved 20% of the beam pattern receiving performance and 13 dB correlation value improvement by eliminating the interference mirror images.

Across-wind excitation mechanism for interference of twin tall buildings in tandem arrangement

  • Zu, G.B.;Lam, K.M.
    • Wind and Structures
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    • v.26 no.6
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    • pp.397-413
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    • 2018
  • Excitation mechanism of interference effect between two tall buildings is investigated with wind tunnel experiments. Synchronized building surface pressure and flow field measurements by particle image velocimetry (PIV) are conducted to explore the relationship between the disturbed wind flow field and the consequent wind load modification for twin buildings in tandem. This reveals evident excitation mechanisms for the fluctuating across-wind loads on the buildings. For small distance (X/D < 3) between two buildings, the disturbed flow pattern of impaired vortex shedding is observed and the fluctuating across-wind load on the downstream building decreases. For larger distance ($X/D{\geq}3$), strong correlation between the across-wind load of the downstream building and the oscillation of the wake of the upstream building is found. By further analysis with conditional sampling and phase-averaged techniques, the coherent flow structures in the building gap are clearly observed and the wake oscillation of the upstream building is confirmed to be the reason of the magnified across-wind force on the downstream building. For efficient PIV measurement, the experiments use a square-section high-rise building model with geometry scale smaller than the usual value. Interference factors for all three components of wind loads on the building models being surrounded by another identical building with various configurations are measured and compared with those from previous studies made at large geometry scale. The results support that for interference effect between buildings with sharp corners, the length scale effect plays a minor role provided that the minimum Reynolds number requirement is met.

Optical Encryption System Using Two Linear Polarizer and Phase Mask (두 선형 편광기와 위상 마스크를 사용한 광 암호화 시스템)

  • 배효욱;신창목;서동환;박세준;조웅호;김수중
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.3
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    • pp.10-18
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    • 2003
  • In this paper, we propose an optical encryption system based on the encryption of information using the phase component of a wavefront and orthogonal polarization in a Mach-Zehnder interferometer. Since the incoherence of the two perpendicularly polarized lights removes interference component, the decrypted image is stable. In encryption process, the original image is converted into an image having random polarization state by the relative phase difference of horizontal polarization and vertical polarization, so we cannot obtain the original information from the random polarization distribution. To decrypt an Image, the random polarization distribution of encrypted image is divided into two orthogonal components, then key image must be placed on vertical path of Mach-Zehnder interferometer. The decrypted image is obtained In the form of intensity by use of an analyzer.

Deep Learning-based Professional Image Interpretation Using Expertise Transplant (전문성 이식을 통한 딥러닝 기반 전문 이미지 해석 방법론)

  • Kim, Taejin;Kim, Namgyu
    • Journal of Intelligence and Information Systems
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    • v.26 no.2
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    • pp.79-104
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    • 2020
  • Recently, as deep learning has attracted attention, the use of deep learning is being considered as a method for solving problems in various fields. In particular, deep learning is known to have excellent performance when applied to applying unstructured data such as text, sound and images, and many studies have proven its effectiveness. Owing to the remarkable development of text and image deep learning technology, interests in image captioning technology and its application is rapidly increasing. Image captioning is a technique that automatically generates relevant captions for a given image by handling both image comprehension and text generation simultaneously. In spite of the high entry barrier of image captioning that analysts should be able to process both image and text data, image captioning has established itself as one of the key fields in the A.I. research owing to its various applicability. In addition, many researches have been conducted to improve the performance of image captioning in various aspects. Recent researches attempt to create advanced captions that can not only describe an image accurately, but also convey the information contained in the image more sophisticatedly. Despite many recent efforts to improve the performance of image captioning, it is difficult to find any researches to interpret images from the perspective of domain experts in each field not from the perspective of the general public. Even for the same image, the part of interests may differ according to the professional field of the person who has encountered the image. Moreover, the way of interpreting and expressing the image also differs according to the level of expertise. The public tends to recognize the image from a holistic and general perspective, that is, from the perspective of identifying the image's constituent objects and their relationships. On the contrary, the domain experts tend to recognize the image by focusing on some specific elements necessary to interpret the given image based on their expertise. It implies that meaningful parts of an image are mutually different depending on viewers' perspective even for the same image. So, image captioning needs to implement this phenomenon. Therefore, in this study, we propose a method to generate captions specialized in each domain for the image by utilizing the expertise of experts in the corresponding domain. Specifically, after performing pre-training on a large amount of general data, the expertise in the field is transplanted through transfer-learning with a small amount of expertise data. However, simple adaption of transfer learning using expertise data may invoke another type of problems. Simultaneous learning with captions of various characteristics may invoke so-called 'inter-observation interference' problem, which make it difficult to perform pure learning of each characteristic point of view. For learning with vast amount of data, most of this interference is self-purified and has little impact on learning results. On the contrary, in the case of fine-tuning where learning is performed on a small amount of data, the impact of such interference on learning can be relatively large. To solve this problem, therefore, we propose a novel 'Character-Independent Transfer-learning' that performs transfer learning independently for each character. In order to confirm the feasibility of the proposed methodology, we performed experiments utilizing the results of pre-training on MSCOCO dataset which is comprised of 120,000 images and about 600,000 general captions. Additionally, according to the advice of an art therapist, about 300 pairs of 'image / expertise captions' were created, and the data was used for the experiments of expertise transplantation. As a result of the experiment, it was confirmed that the caption generated according to the proposed methodology generates captions from the perspective of implanted expertise whereas the caption generated through learning on general data contains a number of contents irrelevant to expertise interpretation. In this paper, we propose a novel approach of specialized image interpretation. To achieve this goal, we present a method to use transfer learning and generate captions specialized in the specific domain. In the future, by applying the proposed methodology to expertise transplant in various fields, we expected that many researches will be actively conducted to solve the problem of lack of expertise data and to improve performance of image captioning.

Development of microscopic surface profile estimation algorithm through reflected laser beam analysis (레이저 반사광 분석을 통한 미세 표면 프로파일 추정 알고리즘의 개발)

  • Seo Young-Ho;Ahn Jung-Hwan;Kim Hwa-Young;Kim Sun-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.11 s.176
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    • pp.64-71
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    • 2005
  • In order to measure surface roughness profile, stylus type equipments are commonly used, but the stylus keeps contact with surface and damages specimens by its tip pressure. Therefore, optics based measurement systems are developed, and light phase interferometer, which is based on light interference phenomenon, is the most noticeable research. However, light interference based measurements require translation mechanisms of nano-meter order in order to generate phase differences or multiple focusing, thus the systems cannot satisfy the industrial need of on-the-machine and in-process measurement to achieve factory automation and productive enhancement. In this research, we focused light reflectance phenomenon rather than the light interference, because reflectance based method do not need translation mechanisms. However, the method cannot direct]y measure surface roughness profile, because reflected light consists of several components and thus it cannot supply surface height information with its original form. In order to overcome the demerit, we newly proposed an image processing based algorithm, which can separate reflected light components and conduct parameterization and reconstruction process with respect to surface height information, and then confirmed the reliability of proposed algorithm by experiment.

Two-Dimensional 8/9 Error Correcting Modulation Code

  • Lee, Kyoungoh;Kim, Byungsun;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.5
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    • pp.215-219
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    • 2014
  • In holographic data storage (HDS), a high transmission rate is accomplished through the use of a charge coupled device array for reading two-dimensional (2D) pixel image data. Although HDS has many advantages in terms of storage capacity and data transmission rates, it also features problems, such as 2D intersymbol interference (ISI) by neighboring pixels and interpage interference (IPI) by multiple images stored in the same holographic volume. Modulation codes can be used to remove these problems. We introduce a 2D 8/9 error-correcting modulation code. The proposed modulation code exploits the trellis-coded modulation scheme, and the code rate is larger (about 0.889) than that of the conventional 6/8 balanced modulation code (an increase of approximately 13.9%). The performance of the bit error rate (BER) with the proposed scheme was improved compared with that of the 6/8 balanced modulation code and the simple 8/9 code without the trellis scheme.

Wind Tunnel Test of a Canard Airplane

  • Chung, Jin-Deog;Cho, Ta-Hwan;Lee, Jang-Yeon;Sun, Bong-Zoo
    • Journal of Mechanical Science and Technology
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    • v.16 no.1
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    • pp.125-131
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    • 2002
  • A low speed wind tunnel test was conducted for a canard airplane model in KARI LSWT. The purpose of the presented paper is to investigate the proper testing approach to correct tare precisely and the interference effects for the canard models which has 21% of canard-to-wing area ratio. Most of tests were performed with image system installation for various elevator deflection conditions at the flexed canard incidence angles. To evaluate the effectiveness of the image system, the obtained correction quantity at an zero elevator setting condition with image system was applied to the rest of elevator deflections and compared with the acquired results for all elevator deflections with image system. Test result showed that the amount of correction quantities were strongly dependent on the elevator deflections, and the difference in aerodynamic coefficients for two approaches was gradually amplified as the elevator deflection angles increased. An adoption of the image system was strongly recommended for the higher canard-to -wing area ratio model, if a proper level of accuracy was required.

Fabrication of Real-Time Hologram for the Implementation of 3-D Moving Picture (3차원 동영상을 구현하기 위한 실시간 홀로그램의 제작)

  • 박세준;배장근김수중
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.977-980
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    • 1998
  • A real-time holography system using LCD with CCD camera is proposed. In this system, the rainbow hologram is used since it can be reconstructed by white light source. And to record on CCD camera, a kind of in-line holography method is used to widen the width of the fringe pattern. The interference fringe pattern by proposed system is detected with CCD camera and transferred to the LCD A 3-dimensional image is reconstructed when a white light source illuminates the LCD. So it can represent 3 dimensional moving images at real-time. In this paper, to confirm the usefulness of the proposed method, the reconstructed image by holographic film is compared to the same reconstruct image by LCD. In the recording of the interferenced processing, the optimal ratio of the reference and object beam intenstiy is also investigated.

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Adaptive Data Hiding based on Turbo Coding in DCT Domain

  • Yang, Jie;Lee, Moon Ho;Chen, Xinhao
    • Journal of Broadcast Engineering
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    • v.7 no.2
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    • pp.192-201
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    • 2002
  • This paper develops a novel robust information hiding technique that uses channel codes derived from the error-correcting coder. The message encoded by the cover encoder is hidden in DCT transform domain of the cover image. The method exploits the sensitivity of human eyes to adaptively embed a visually recognizable message in an image without affecting the perceptual quality of the underlying cover image. Experimental results show that the proposed data hiding technique is robust to cropping operations, lossy JPEG compression, noise interference and secure against known stego attacks. The performance of the proposed scheme with turbo coder is superior to that without turbo coder.

A Study on the Development of Measurement Setup for Crater Wear by Diffraction Grating in Turning (선삭에서 회절격자를 이용한 크레이터마모 측정장치 개발에 관한 연구)

  • Kim, Yeong-Il;Kim, Se-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.9 no.1
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    • pp.82-95
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    • 1992
  • There is the high interest for sensing of tool wear with the aim of controlling machine tools productivity from the point of view of qualitity. Difficulties in this measurement are also known. This study is on the development of measurement setup for crater wear by CCD image inturning. In this study, the crater wear measurement system consists of the He-Ne gas laser, diffraction grating. CCD camera, noise filter, slit, microcomputer, diverging lens, converging lens and so on. He-Ne laser beam passes through a diverging lens and a diffraction grating is positioned properly. A converging lens focuses so that the interference fringes can be obtained on the crater wear. Performance test revealed that the developed image technique provides precise, absolute tool-wear quantification and reduces human measurement errors. The results obtained are as follows 1. The digitizing of one image requires less than 2ses. 2. It can give detailed information on crater wear with limited times and errors 3. All parameters required by specification are easily obtained for several points of the cutting edge.

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