• Title/Summary/Keyword: 기하광학이론

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Target Scattering Echo Simulation for Active Sonar System in the Geometric Optics Region (기하광학영역에서의 능동소나 표적신호합성)

  • 신기철;박재은;김재수;최상문;김우식
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.3
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    • pp.91-97
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    • 2001
  • Since the new field information of target signal is important in the development and verification of active sonar system, experimental method and simulation technique are widely used in order to analyze the detail characteristics of target scattered echoes. Therefore, in this paper, the scale target experiment is performed to develope and Improve the target signal simulation model. Since the experimental results show that the specular reflection is the major component among scattering mechanisms, the target signal simulation model based on the Geometric Optics Theory (GOT) is developed. Complex target is separated into simple shapes, known as canonical shape. The contribution from individual canonical shapes are summed with proper phase and amplitude to produce the target strength of the whole complex body. Simulated target signal is compared with the experimental results and discussed.

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A Hybrid RCS Analysis Code Based on Physical Optics and Geometrical Optics (PO-GO 연계기법을 이용한 RCS 해석코드 개발)

  • Jang, Min-Uk;Myong, Rho-Shin;Jang, In-Mo;Lee, Dong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.11
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    • pp.958-967
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    • 2014
  • A hybrid method based on high-frequency asymptotic optics was developed in order to predict the RCS of flying vehicles for RCS reduction studies. In cavity return, the rays are assumed to bounce from the inlet cavity based on the laws of geometrical optics and to exit the cavity via the aperture. In other parts of a flying vehicle, the physical optics method is applied to compute the back-scattered field from the solid surface. The hybrid method was validated by considering simple models of sphere and sphere with cavity. In addition, RCS analysis of a flying vehicle was conducted using the new hybrid electromagnetic scattering method based on physical optics and geometrical optics theories.

Development of Radar Cross Section Analysis Program for Complex Structures (복합 구조물의 레이더 반사면적 해석 프로그램 개발)

  • Kwon, Hyun-Wung;Hong, Suk-Yoon;Song, Jee-Hun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.20 no.4
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    • pp.435-442
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    • 2014
  • In this paper, radar cross section (RCS) analysis program, RACSAN has been developed to predict RCS of complex structures. RACSAN is based on the high frequency range analysis method of Kirchhoff approximation in physical optics (PO). This program can present RCS including multi-bounce effect in complex structures by combination of geometric optics (GO) and PO method. GO method has a concern in the evaluation of the effective area, and PO method is involved in the calculation of RCS for the final effective area that is evaluated by GO method. Comparisons of the predicted results and analytical solutions showed that the developed program could be an effective tool for predicting RCS in complex structures.

Observation of Geometrical Waves by Solid Elastic Cylinders at Large K-A (Ka 가 큰 원통에서의 Geometrical wave 관찰)

  • 노희설
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1985.10a
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    • pp.19-22
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    • 1985
  • 철(Iron)을 재질로한 ka가 큰 원통에서의 산란파를 측정 분석하였다. ka가 클 경우 산란파는 주로 Geometrical wave에 의해 구성되며, 이 Geometrical wave는 기하광학의 법칙을 따르게 된다. 본 연구에서는 각 mode의 Geometrical wave에 대하여 송.수신 위치에 따른 이론적인 펄스 도달 시간과 측정 분석된 도달시간을 비교하여 Geometrical wave를 관찰하였다.

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Analysis of the indoor radio signal propagation characteristics by ray-tracing technique (Ray-Tracing을 이용한 구내 전파 전파특성 해석)

  • Ryu, Hwang
    • The Journal of Natural Sciences
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    • v.8 no.2
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    • pp.101-109
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    • 1996
  • In this paper, using the derived formula based on field theory both geometrical optics and diffraction theory, several features of same buildings of Bertoni's construction that influence the propagation of signals between antennas located on the same floor have been investigated theoretically and compared with previously studied results.

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Transparent Plate Thickness Measurement Approach Using a Chromatic Confocal Sensor Based on a Geometric Phase Lens (기하 위상 렌즈 기반의 색공초점 센서를 이용한 투명 물질 두께 측정 연구)

  • Song, Min Kwan;Park, Hyo Mi;Joo, Ki-Nam
    • Korean Journal of Optics and Photonics
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    • v.33 no.6
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    • pp.317-323
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    • 2022
  • In this investigation, we describe a chromatic confocal sensor based on a geometric phase lens for measuring the thicknesses of transparent plates. In order to design a compact sensor, a geometric phase lens, which has diffractive and polarizing characteristics, is used as a device to generate chromatic aberration, and a fiber optic module is adopted. The systematic error of the sensor is reduced with wavelength peak detection by Gaussian curve fitting and the common error compensation obtained by the repeatedly consecutive experimental results. An approach to calculate the plate thickness is derived and verified with sapphire and BK7 plates. Because of the simple and compact design of the proposed sensor with rapid measurement capability, it is expected to be widely used in thickness measurements of transparent plates as an alternative to traditional approaches.

Geometrical Analysis and Implementation of the Real-Time Tuning Structure Using Spatial Light Modulator in Photorefractive Tunable Filter (광굴절 가변 필터에서 공간광학변조기를 이용한 실시간 튜닝 구조의 기하학적 해석 및 구현)

  • An, Jun-Won;Kim, Seong-Goo;Kim, Nam
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.12
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    • pp.43-52
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    • 1999
  • We propose a new method for tuning of center wavelength in photorefractive filter using $LiNbO_3$ crystal doped with 0.015Wt.% Fe. through the filter bandwidth property analysis using the geometrical method, a new wavelength selectivity theory was presented. In this scheme, the tuning of the center wavelength can be achieved by the real time incident angle control of the received heam, which was gotten by the spatial light modulator. So, tuning time depend on the response time of the SLM and results in the high speed turing. Because the use of thermally fixed grating in our filter, it has uniform diffraction property to the all filtering wavelength. Designed tunable filter has 4nm bandwidth and composed of the three channel with 10nm space. From the optical experiment, we get the 4.5nm, 4.25nm, 4nm bandwidth and 1530.5nm, 1540.5nm, 1549.5nm center wavelength respectively.

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Correction method for the Variation of the Image Plane Generated by Various Symmetric Error Factors of Zoom Lenses of Digital Still Cameras and Estimation of Defect Rate Due to the Correction (디지털 카메라용 줌렌즈에서 대칭성 오차요인에 의한 상면 변화의 보정과 이에 따른 불량률 예측)

  • Ryu, Jae-Myung;Kang, Geon-Mo;Lee, Hae-Jin;Lee, Hyuck-Ki;Jo, Jae-Heung
    • Korean Journal of Optics and Photonics
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    • v.17 no.5
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    • pp.420-429
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    • 2006
  • In the zoom lens of digital still cameras with the variation of the image plane generated by various symmetric error factors such as curvature, thickness and refractive index error of each lens surface about the optic axis, we induce a theoretical condition to fix constantly the image plane by translating the compensator group of the zoom lens by using the Gaussian bracket. We confirm the validity of this condition by using three examples of general zoom lens types with 3, 4, and 5 groups, respectively. When these error factors are randomly changed within the range of tolerance according to the Monte Carlo method, we verify that the distributions of the degree of moving of the compensator are normal distributions at three zoom lens types. From capability analysis using these results, we theoretically propose the method estimating the standard deviation, that is, sigma-level, as a function of the maximum movement of the compensator.

Elemental image resizing and the analysis of the reconstructed three dimensional image in the integral imaging system (집적결상법에서 기본영상의 크기 변환에 따른 3차원 재생영상의 특성 분석)

  • Ser, Jang-Il;Shin, Seung-Ho
    • Korean Journal of Optics and Photonics
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    • v.16 no.3
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    • pp.225-234
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    • 2005
  • In the integral imaging system for 3D display, the elemental image size is closely related to the several variables, such as the size of elemental lens, the distance between elemental lens and elemental image, etc., on the pick up system. We have analyzed the geometric relation between the variables. In addition, we have investigated the integrated image variation for the individual and whole conversion of the size of the elemental images, different from in pick up process, and presented experimental results.

FTIR and Moisture Effects on Optical Information Transfer at Interface of Air and Glass (공기-유리 계면에서 광학정보 전달에 미치는 불완전 반사 및 수분 효과)

  • Han, Won Heum;Han, Ji Heum;Kim, Jee Hyen;Jung, Hyung Sik;Lee, Moon Ho
    • Journal of Adhesion and Interface
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    • v.13 no.2
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    • pp.73-84
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    • 2012
  • The transfer mechanism of optical information at the interface of air and glass (the air-glass IF) has been investigated by thoroughly fulfilling the theoretical and experimental analyses regarding the FTIR (Frustrated Total Internal Reflection) and moisture effects on the fingerprint onto a glass cup with water. As for the fingerprint onto a glass cup with water its image was observed to be very vivid, which turned out to be due to the difference between the two light intensities reflected on the air-glass IF and the wet fingerprint ridge by manipulating the optical theories such as Fresnel relation, Snell's law, FTIR, GT (general transmission) and so on. In addition, the experimental inspection for FTIR and moisture effects on the fingerprint image also evidenced the fact that the vivid fingerprint image originated from the moisture effect rather than the FTIR phenomenon.