• Title/Summary/Keyword: 다중반사

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경사입사각증착법을 이용한 이산화 티타늄 박막 기반의 고반사 분포 브래그 반사기 제작 및 특성

  • Guan, Xiang-Yu;Im, Jeong-U;Jeong, Gwan-Su;Yu, Jae-Su
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.350.1-350.1
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    • 2014
  • 분포 브래그 반사기(distributed Bragg reflector; DBR)는 광센서, 도파로, 태양전지, 반도체 레이저 다이오드, 광검출기와 같은 고성능 광 및 광전소자 응용분야에 널리 사용되고 있다. 일반적으로, DBR은 박막의 두께를 4분의 1 파장(${\lambda}/4$)으로 가지는 서로 다른 저굴절율 물질과 고굴절율 물질을 교대로 적층 (pair)한 다중 pair로 제작되어지며, DBR의 반사 특성과 반사대역폭은 두 물질의 굴절율 차이와 pair의 수에 영향을 받는다. 그러나, 서로 다른 굴절율을 갖는 두 물질을 이용하는 DBR의 경우, 두 물질간 열팽창계수의 불일치, 접착력 문제, 높은 굴절율 차이를 갖는 물질 선택의 어려움 등 많은 문제점을 지니고 있다. 최근, 경사입사각증착법을 이용한 동일 재료(예, 인듐 주석 산화물, 게르마늄, 실리콘)기반의 DBR 제작 및 특성에 대한 연구가 보고되고 있다. 높은 입사각을 갖고 박막이 증착될 경우, 저율을 갖는 다공박막 제작이 가능하여 경사입사각증착법으로 homogeneous 물질 기반의 고반사 특성을 갖는 다중 pair의 DBR을 제작할 수 있다. 본 실험은, 갈륨비소 기판 위에 경사입사각증착법 및 전자빔증착법을 이용하여 중심파장 960 nm가 되는 이산화 티타늄 기반의 DBR을 제작하였고, 제작된 샘플의 증착된 박막의 표면 및 단면의 프로파일은 주사전자현미경을 사용하여 관찰하였으며, UV-Vis-NIR 스펙트로미터를 이용하여 반사율 특성을 조사하였다.

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Analysis of Radar Cross Section for Naval Vessels with Metamaterials and Radar Absorbing Materials (메타물질 및 전파흡수체를 적용한 함정의 레이다 반사면적 해석)

  • Hwang, Joon-Tae;Hong, Suk-Yoon;Kwon, Hyun-Wung;Kim, Jong-Chul;Song, Jee-Hun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.21 no.6
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    • pp.737-743
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    • 2015
  • This paper are mainly focusing on the facts influencing on RCS reductions, appling radar absorbing materials by using RCS contributions of elements and appling a metamaterials which is high-tech radar absorbing materials. RCS analysis results are given for a simplified ship model, with radar absorbing materials and metamaterials cause RCS reduction in terms of mean values.

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.

Design of a Multi Dielectric Coating against Non-invaisive Attack (비침투형 공격에 강한 다중 유전체 코팅 설계)

  • Kim, Tae-Yong;LEE, HoonJae
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.6
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    • pp.1283-1288
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    • 2015
  • In general, IC chip circuit which is operating a cryptographic computation tends to radiate stronger electromagnetic signal to the outside. By using a power detecter such as a loop antenna near cryptographic device, the encryption key can be identified by probing a electromagnetic signal. To implement a method against non-invasive type attack, multi dielectric slab structure on IC chip to suppress radiated electromagnetic signal was introduced. Multiple dielectric slab was implemented by suitably configured to have the Bragg reflection characteristics, and then the reflection response was computed and verified its effectiveness. As a result, the thickness of the dielectric coating was 2mm and the reflection response characteristics for the vertical incidence was achieved to be 91% level.

Rural Land Cover Classification using Multispectral Image and LIDAR Data (디중분광영상과 LIDAR자료를 이용한 농업지역 토지피복 분류)

  • Jang Jae-Dong
    • Korean Journal of Remote Sensing
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    • v.22 no.2
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    • pp.101-110
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    • 2006
  • The accuracy of rural land cover using airborne multispectral images and LEAR (Light Detection And Ranging) data was analyzed. Multispectral image consists of three bands in green, red and near infrared. Intensity image was derived from the first returns of LIDAR, and vegetation height image was calculated by difference between elevation of the first returns and DEM (Digital Elevation Model) derived from the last returns of LIDAR. Using maximum likelihood classification method, three bands of multispectral images, LIDAR vegetation height image, and intensity image were employed for land cover classification. Overall accuracy of classification using all the five images was improved to 85.6% about 10% higher than that using only the three bands of multispectral images. The classification accuracy of rural land cover map using multispectral images and LIDAR images, was improved with clear difference between heights of different crops and between heights of crop and tree by LIDAR data and use of LIDAR intensity for land cover classification.

The Seismic Multipulse Deconvolution (다중펄스 방법을 이용한 디컨벌루션)

  • Shon, Howoong
    • Economic and Environmental Geology
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    • v.28 no.5
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    • pp.487-491
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    • 1995
  • The multipulse model of linear predictive coding (LPC), which has been successfully used for compressing of speech signals into an impulse excitation, is here applied to seismic data which contains multiples. Multiples are happened by successive reflection between layers and make the seismic interpretation difficult In this paper, the author applied the enhanced multipulse method to seismic traces to compress source-wavelets into spikes, and to eliminate/reduce multiples. The enhanced multipulse method which was applied to seismic traces extracted the amplitudes and locations of reflectivity function, which depicts the subsurface configuration, by iterative computation of autoregressive (AR) estimation method.

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해상 탄성파탐사 기법을 이용한 단층파쇄대 분석 적용사례

  • 이준석;최세훈;김재관;최원석
    • Geotechnical Engineering
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    • v.20 no.4
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    • pp.38-49
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    • 2004
  • 해상 반사법탐사는 해저 지반의 지층구조를 파악하는 기술로서 해저지층에 부존하는 가스나 골재 등 해저자원 탐사와 해저의 저장시설 건설, 파이프라인 설치 등 다양한 해양 토목공사를 위한 지반조사에 사용된다. 해상 반사법탐사의 기본적인 원리는 해수면 근처에서 인공적으로 음파를 발생시켜 해저면 하부의 지층으로 침투시키면 서로 다른 물성을 갖는 지층의 경계면에서 일부 음파는 반사되는데, 이 반사파를 수신하는 것이다. 탐사과정에서 얻어진 트레이스에는 반사파 이외에도 직접파, 다중반사파와 같은 잡음이 섞여있는데 자료처리를 통해 탄성파 단면도를 작성하고, 이를 해석하여 해저지반의 지질학적 구조를 파악하는 것이 해상 반사법탐사의 목적이다.

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PC-based Processing of Shallow Marine Multi-channel Seismic Data (PC기반의 천해저 다중채널 탄성파 자료의 전산처리)

  • 공영세;김국주
    • 한국해양학회지
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    • v.30 no.2
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    • pp.116-124
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    • 1995
  • Marine, shallow seismic data have been acquired and processed by newly developed multi-channel(6 channel), PC-based digital recording and processing system. The digital processing system includes pre-processing, swell-compensation filter, frequency filter, gain correction, deconvolution, stacking, migration, and plotting. The quality of processed sections is greatly enhanced in terms of signal-to-noise ratio and vertical/horizontal resolution. The multi-channel, digital recording, acquisition and processing system proved to be and economical, efficient and easy-to-use marine shallow seismic tool.

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Reflection Characteristics from Multiple Dielectric Slabs for PUF Modeling (PUF 모델링을 위한 다중 유전체 슬래브의 반사 특성)

  • Kim, Tae Yong;Lee, Hoon-Jae
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.477-479
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    • 2015
  • PUF technology is to prevent a copy of information from digital device and it can be seen whether cloning through its difference for process of implementation corresponding to wire and gate delay, etc. In this paper, multiple dielectric slabs on digital device is investigated to implement physical crypto device based on coating PUF type and its reflection characteristics is analyzed.

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Effect of the Reflectivity of Both Facets and the Phase of a Phase Tuning Section on the Yield Characteristics of a Multisection Complex-Coupled DFB Laser with Self-Pulsation Frequency of THz Region (양 단면 반사율과 위상 조정 영역의 위상이 Self-Pulsation 주파수가 THz 대역인 다중 영역 Complex-Coupled DFB 레이저의 수율 특성에 미치는 영향)

  • Kim, Tae-Young;Park, Jae-Woo;Kim, Boo-Gyoun
    • Korean Journal of Optics and Photonics
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    • v.19 no.3
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    • pp.208-218
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    • 2008
  • We investigate the effect in terms of yield of the reflectivity of both facets and of the phase of a phase tuning section on the self-pulsation (SP) characteristics of multisection complex-coupled (CC) DFB lasers with self-pulsation frequency of the THz region. When the grating phases on both facets of a multisection CC DFB laser are fixed as 0, the variation of SP frequency increases as the reflectivity of both facets increases, while that of SP frequency decreases as the coupling ratio (CR) and the coupling strength increase. For the coupling strength of 3, the range of the phase of a phase tuning section with yields greater than 80% decreases as the CR and the reflectivity of both facets increases. For the coupling strength of 4, the range of the phase of a phase tuning section with yields greater than 80% increases as the CR and the reflectivity of both facets increases.