• Journal of KSNVE
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• v.9 no.3
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• pp.509-516
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• 1999

The ESPI (Electronic Speckle Pattern Interferometry) algorithm has been simulated to calculate vibrational modes of a thin right-angled STS304 plate. The phase transformation of the reference wave of the ESPI is carried out only one time during vibration in order to clarify ESPI speckle patterns. Two dimensional vibrational modes are calculated from one ESPI pattern before vibration onset and two ESPI patterns during vibrations but with and without the phase transformation. The ESPI harmonic results are compared with those derived from the finite element method (FEM), and they agree very well. Additionally a phase unwrapping algorithm has been newly developed to derive a displacement map from an ESPI phase map.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.25-32
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• 2000

Digital watermarking has been recently proposed as the means of intellectual property right protection of multimedia data. We present a novel watermarking scheme to hide a copyright information in a digital image. The method Is based on the 2D DWT(Discrete Wavelet Transform) and image statistics. Gaussian and Laplacian noises as the watermarks are added to the large wavelet coefficients at the high and middle frequency bands in the wavelet domain. Experimental results show that the proposed Laplacian watermark is stronger to several common image distortions, such as noises, JPEG coding as different qualities, Gaussian blurring, and edge enhancement.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1566-1569
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• 2008

The flow visualization is conducted in order to investigate an unsteady flight characteristic of a model dragonfly. The flapping wings are analyzed using smoke-wire and high speed camera. The results of this experiment show that three mechanisms and high incidence angle of the wings are responsible for the lift. The leading edge vortex, which is induced by the rapid acceleration of the wing at the beginning of a stroke, causes the lift enhancement. The delayed stall during the stroke and the fast supination and pronation of the wing near the end of each stroke are also responsible for the lift generation.

• Journal of the Korean Institute of Navigation
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• v.13 no.1
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• pp.11-20
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• 1989

Radar image data were collected through the on-line data acquisition system of A/D converter and personal computer, and the image was restorated on CRT or plotter after digital image processing of the data. The digital image processing system which was developed for this study, consisted of some kinds of software as follows : rearrangement, transformation, and enhancement of the image data in real space or frequency space by Fourier transform, edge detection of the image, compact processing, state inferential processing, and so on. Since the image of PPI radar sweeps from the center to the circumference of a circle, the image within a given period has the shape of fan. Therefore the acquired data were transformed to have the same interval as that of data in outmost concentricity. The results of various image processing methods using transformed data were better than those of the methods using original data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.1003-1006
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• 2012

The image correction algorithm and system design for CMOS sensor to enhance the image resolution is presented in this paper. The proposed algorithm finds out the image cell from the sensor and process them by the limited memory configuration. The evaluation of the method is done by the designed hardware system. The experimental results are capable of improving contrast per channel and of sensing equalized image quality on an edge of image.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.148-150
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• 2012

외부 환경에 안개가 존재하는 경우, 영상처리의 다양한 알고리즘을 사용하기 어렵다. 이때 안개가 짙은 정도인 전달량을 이용하여 안개를 제거한다. 안개 제거를 위한 대표적인 방법 중 하나인 Dark Channel Prior 알고리즘은 영상의 색 정보를 이용하여 안개의 전달량을 예상한다. 하지만 RGB 전 채널 모두 높은 값을 갖고 있는 영역이, 전달량을 찾는 마스크보다 클 때 전달량을 잘못 예상하게 된다. 본 논문에서는 영상의 edge 정보를 이용하여 영상의 안개가 짙은 정도에 따라 영역을 분할 후 잘못 예상된 전달량을 보정하는 방법을 제안한다. 잘못된 전달량 예상을 통해 색이 왜곡되는 부분을 제거함으로서 기존의 알고리즘과 비교하여 영상 내의 색상이 자연스럽게 안개가 제거된 결과를 얻었다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.502-505
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• 2006

본 논문은 고해상도의 영상을 처리하는 이동기기 등에 사용되는 SoC(System On a Chip)에 구현이 용이한 효과적인 화질 향상 (잡음감소와 윤곽강조) 을 위한 방법과 구조에 대한 것이다. 최근 이동기기의 발전과 진화에 따라 여러 형태의 이동기기가 개발되고 있는데 그 중 최근 인기를 끌고 있는 포터블 미디어 플레이어 (PMP)나 HD(Hight Definition)급 camcorder 등이 고해상도의 영상을 처리하는 이동기기로 분류될 수 있다. 이러한 이동기기에서 고해상도 영상에 대한 화질 향상을 기존의 복잡한 방법을 사용해 처리한다면 메모리 대역폭이나 하드웨어 크기 등의 증가로 이동기기에서 구현하는데 어려움이 따른다. 이에 본 논문에서는 이러한 이동기기에서의 고해상도의 화질 향상을 입력영상의 종류에 따라 선택적으로 메모리 대역폭 사용 없이 하드웨어 크기를 최소화하여 FPGA (field programmable gate array)나 ASIC (application specific integrated circuit)으로 구현이 용이하도록 하는 방법과 구조에 대해 설명하고 실제 영상을 가지고 실험한 결과로 주관적 화질 향상 효과를 가져 온 것을 확인할 수 있었다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.443-446
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• 2007

원영상과 목적영상 사이의 원근 변환(projective transform)에 의해서 생성되는 조강도 영상은 영상의 확대와 축소가 동시에 일어나는 특징을 가지고 있다. 조감도 영상을 구성하는 과정은 원영상의 위치에 따라서 원영상을 확대하거나 축소하여 목적영상을 만들어 내기 때문에, 원영상의 확대와 축소영역을 목적영상에 적합하게 나타내기 위한 보간법이 필요하다. 이중선형 보간법(bilinear interpolation)은 낮은 연산량 때문에 영상변환에 많이 사용되는 보간법이다. 하지만 영상의 확대와 축소 영역에서는 흐려지거나 에일리어싱(aliasing) 효과에 의한 아티팩트(artifact)가 일어나는 문제점을 가지고 있다. 이러한 문제점을 개선하기 위해서 고주파성분을 유지하는 에지(edge)정보 기반의 변형된 EWA를 사용 한다. 그리고 엔티 에일리어싱(anti-aliasing)을 수행하는 MIP-mapping을 이용한 보간법을 통해서 축소 영역에서 발생하는 에일리어싱 문제를 해결하여 조감도 영상의 화질을 개선한다.

• Journal of Information Display
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• v.5 no.1
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• pp.7-15
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• 2004

A highly simplified backlight unit mainly composed of diffractive grating in sub-micron order imprinted light-guide plate (LGP) is proposed for edge-lit backlight unit. Optical characteristics of the imprinted LGP are examined by RCWA and the performance is verified through Monte Carlo simulation. Results show that the diffraction efficiency, luminous flux and its uniformity over the area are significantly affected by the angle of incident ray. Consequently couples of design considerations are additionally proposed to enhance luminous flux. In terms of peak luminance and out-coupling luminous flux, the experimental results are agreed well with the performance simulation. Finally, compared with optical characteristics of conventional backlight unit, we could conclude that the proposed simplified backlight unit made of diffractive grating imprinted light-guide plate is a good substitute for the conventional backlight unit.

• Transactions of Materials Processing
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• v.11 no.7
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• pp.620-627
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• 2002

The purpose of this paper is the development of an automated measurement system for micro spring based on the digital image processing technique. This micro spring can be used in various engineering applications such as filament, load bearing springs, hard disk suspension and many others. Main functionality of the micro spring inspection system is to measure the representative pitch of the micro spring. The derivative operators are used for edge detection in gray level image. Measurement system developed in this paper consisted of new auto feeding mechanism to take advantage of air pressure. In the process of development of the micro spring inspection system based on the image processing and analysis, strong background technology and know-how have been accumulated to measure micro mechanical parts.