• 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.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.495-498
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• 1998

수중폭발성음원인 SUS(signal underwater sound)는 수중에서의 폭발과 동시에 충격파와 기포파들이 연속적으로 발생한다. 이러한 신호는 광범위한 주파수대역을 가지고 전파거리가 길어지면서 굴절과 반사등의 다중경로 전파효과에 의한 신호의 변형까지 생긴다. (1,2,3). 본 연구에서는 deconvolution 방법을 이용하여 수신신호중에서 기포파효과를 최소화시켜 충격파의 수신기 도달시간을 파악하고, 각 충격파들의 전파경로를 추정하여 이 중 직접경로와 해저면 반사경로의 신호를 이용하여 해저면 반사계수를 계산하였다.

• 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.

• 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.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.117-118
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• 2010

위성 주사 및 촬영자료는 지표면의 반사광을 다중분광 형태로 주사하여 기록된다. 그리나 각 밴드에 기록된 지표복사체의 반사치는 피복체의 분광특성만을 나타내기 보다는 태양고도 및 방위, 그리고 지형 등에 따른 방향성 영향이 포함되기 때문에 산림의 관리 및 이용을 위한 기초자료로 식생지수를 추정할 때에 오차의 범위를 넘어 오류가 발생한다. 따라서 동일 방향성 조건의 수종에 따른 고유 정규식생지수(Normalized Difference Vegetation Index, 이하 NDVI) 값을 구하기 위해서는 지형효과에 대한 보정이 필요하다. 본 연구에서는 QuickBird 다중분광(MS)자료 기반의 NDVI값을 사면향별로 분석하여 산림 NDVI의 방향성을 증명하였다.

• Korean Journal of Optics and Photonics
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• v.26 no.5
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• pp.275-282
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• 2015

The effective reflection coefficients for light obliquely incident upon a substrate coated with uniaxially anisotropic films and with isotropic films are derived. Multiple reflections inside anisotropic films, as well as those inside isotropic films, are properly treated. These expressions, together with the related ellipsometric expressions, can be used to find the nonuniform distribution of an uniaxially anisotropic film perpendicular to the film's surface, by approximating it as consisting of uniaxially anisotropic uniform layers and applying the conventional modeling technique for spectroscopic ellipsometry.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.429-435
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• 2007

The present study proposed a method fer simulating reflective boundary conditions in Boussinesq wave propagation model by lining lateral boundaries like breakwaters and seawalls with artificial sponge layers. In order to find out the reflective characteristics of sponge layers, 1D numerical experiments were performed varying the relative sponge width (sponge width/wave length). The results showed that the reflection coefficient can be effectively realized from no reflection to full reflection simply by adjusting the relative sponge width. Based on the results, a multiple regression formula was proposed to delineate the relationship among the reflection coefficient and other dimensionless variables. Finally, the reflective sponge layer was applied to a semi-infinite breakwater, demonstrating that it can also be successfully employed in 2D applications.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.918-925
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• 2017

Multiple reflections on exterior equipment with complex shape on naval ships cause unexpectedly high Radar Cross Section (RCS) distributions, and the directions of reradiated electromagnetic waves are hard to predict. Therefore, the optimum arrangement of exterior equipments should be considered according to the Radar Absorbing Structure (RAS) method. In this paper, the optimum arrangement for exterior equipments was determined to reduce multiple reflections and RCS even with complex shapes. The sequential descending arrangement method was used to establish an optimum arrangement algorithm. An LCS-2 type model was selected for optimum exterior equipment arrangements. In order to reduce computational cost, RCS distributions and multiple reflection path analysis of exterior equipments was carried out to select exterior equipments for optimum arrangement, and an optimum arrangement was determined to find positions with minimum RCS values. Also, the RCS reduction effect was analyzed using detectable radar range.

• Electronics and Telecommunications Trends
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• v.15 no.1 s.61
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• pp.38-40
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• 2000

자동 요금 징수 시스템인 ETC(Electronic Toll Collection) 시스템에서 차량의 탑재장치와 비컨(Beacon) 간에 마이크로파가 전파되는 경로를 모델화하였으며 다중 경로에 따른 페이딩 효과를 분석하였다. 또한 환경 변화 즉 강우 시 마이크로파 전파도 고려하여 수치분석을 하였다. 분석결과 강우에 의한 반사면의 반사계수가 변하여 페이딩 효과가 크게 증가하였다. 이런 수치해석 결과를 탑재장치에서 수신된 전압의 크기와 비컨과 차량 사이의 거리로 도시하였다.

• Journal of KIISE:Software and Applications
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• v.37 no.2
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• pp.104-109
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• 2010

The lighting reflection is a common problem in image analysis and causes the many difficulties to extract distinct features in related fields. Furthermore, the problem grows in the rainy night. In this paper, we aim to remove light reflection effects and reconstruct a road surface without lighting reflections in order to extract distinct features. The proposed method utilizes a 3D analysis based on a multiple geometry using captured images, with which we can combine each reflected areas; that is, we can remove lighting reflection effects and reconstruct the surface. At first, the regions of lighting sources and reflected surfaces are extracted by local maxima based on vertically projected intensity-histograms. After that, a fundamental matrix and homography matrix among multiple images are calculated by corresponding points in each image. Finally, we combine each surface by selecting minimum value among multiple images and replace it on a target image. The proposed method can reduces lighting reflection effects and the property on the surface is not lost. While the experimental results with collected data shows plausible performance comparing to the speed, reflection-overlapping areas which can not be reconstructed remain in the result. In order to solve this problem, a new reflection model needs to be constructed.