• Journal of Internet Computing and Services
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• v.4 no.3
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• pp.39-46
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• 2003

Generally, the existing watermarking techniques for copyright protection of a digital image are fragile in geometric distortion and all watermark extractions need the same time regardless of degree of distortion. In this paper, we propose the incremental watermarking technique that used a Complex Wavelet Transform(CWT) in order to solve these problems. The proposed incremental watermarking technique embeds a watermark in a phase component after a CWT with an original image, and a watermark is extracted from an watermarked image by stages. A watermark owner can insist on copyright of an image after comparing a correlation between the extracted watermark and the original watermark if it is larger than the threshold. Also, the incremental watermark extraction determines the extraction time of a watermark by the level of distortion. The proposed technique through performance evaluation displayed that it was robust in geometric distortion than the existing watermarking technique.

• Journal of the Korea Society of Computer and Information
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• v.16 no.3
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• pp.211-218
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• 2011

Because antique Korean Peninsula maps have many historical signification, we can estimate historical evidences by analyzing them. However, it is very difficult to compare antique maps with modern maps because the antique maps were made by arranging local regions. To resolve this difficulty, we transform antique maps by rotating, scaling and translating to compare with a reference map. Each antique map is rotated in the difference of principal axis angles of the target and the reference maps, and its width and height are scaled asymmetrically using width and height ratios of bounding boxes. Finally, the two regions are overlaid by adjusting their centroids, and then the antique map is evaluated by two similarity equations. Experimental results show that the similarities of region ratio and different angle are properly computed according to era. Therefore, the proposed method can be widely used to analyze the antique Korean Peninsula maps.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.2
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• pp.209-220
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• 2000

For non-linear analysis of stiffened shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors and taking into account second order rotational terms in the incremental displacement field. Assumed strain concept is adopted in order to overcome shear locking phenomena and to eliminate spurious zero energy mode. The post-buckling behaviors of stiffened shell structures are traced by modeling the stiffener as a shell element and considering general transformation between the main structure and the stiffener at the connection node. Numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references' results.

• Computational Structural Engineering
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• v.11 no.4
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• pp.155-168
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• 1998

보강된 판 및 쉘구조의 안정성 및 후좌굴을 포함하는 기하학적 비선형 해석을 수행하기 위하여, total Lagrangian formulation에 근거한 연속체의 증분평형방정식으로부터 변형된 쉘요소인 유한요소이론을 제시하였다. 쉘구조의 곡률이 불연속적으로 변하거나 쉘부재들이 유한한 각도로 만나는 보강된 판 및 쉘구조의 비선형 해석이 가능하도록 주부재와 보강재 간의 연결점에 대한 일반적인 변환관계를 제시하였으며 좌굴해석 및 기하학적 비선형해석의 경우에 해의 정확성 및 수렴성을 개선시키기 위하여 접선강도행렬 산정시 회전각의 2차항을 포함시켰다. 또한, shear locking 현상을 극복하기 위하여 감차적분을 적용하였고 쉘구조의 좌굴해석에서는 power method를 적용하여 해석의 효율을 높였으며, 후좌굴해석에서는 변위 및 하중증분법을 적절히 결합시켜 보강된 쉘구조의 후좌굴 거동추적이 용이하였다. 또한, 입력자료를 손쉽게 준비하고 좌굴모드 및 후좌굴거동을 효율적으로 분석하기 위하여 전, 후 처리 프로그램을 개발하였고 다양한 해석예제를 통하여 다른 문헌의 해석결과를 비교함으로써 본 연구에서 개발된 유한요소 해석프로그램의 타당성 및 정확성을 입증하였다.

• The Journal of the Korea Contents Association
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• v.4 no.3
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• pp.107-113
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• 2004

This paper improved the performance of the face recognition system using the PCA/LDA hybrid method based on the facial geometric feature and the Wavelet transform. Because the previous PCA/LDA methods have measured the similarity according to the formal dispersion, they could not reflect facial boundaries exactly In order to recover this defect, this paper proposed the method using the distance between eyes and mouth. If the difference of the measured distances on the query and the training images is over the given threshold, then the method reorders the candidate images according to energy feature vectors of eyes, a nose, and a chin. To evaluate the performance of the proposed method the computer simulations have been performed with four hundred facial images in the ORL database. The results showed that our method improves about 4％ recognition rate over the previous PCA/LDA method.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.670-672
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• 2005

본 논문은 비전을 기반으로 한 감정인식 로봇에 관한 논문이다. 피부스킨칼라와 얼굴의 기하학적 정보를 이용한 얼굴검출과 감정인식 알고리즘을 제안하고, 개발한 로봇 시스템을 설명한다. 얼굴 검출은 RGB 칼라 공간을 CIElab칼라 공간으로 변환하여, 피부스킨 후보영역을 추출하고, Face Filter로 얼굴의 기하학적 상관관계를 통하여 얼굴을 검출한다. 기하학적인 특징을 이용하여 눈, 코, 입의 위치를 판별하여 표정 인식의 기본 데이터로 활용한다. 눈썹과 입의 영역에 감정 인식 윈도우를 적용하여, 윈도우 내에서의 픽셀값의 변화와 크기의 변화로 감정인식의 특징 칼을 추출한다. 추출된 값은 실험에 의해서 미리 구해진 샘플과 비교를 통해 강정을 표현하고, 표현된 감정은 Serial Communication을 통하여 로봇에 전달되고, 감정 데이터를 받은 얼굴에 장착되어 있는 모터를 통해 표정을 표현한다.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.271-275
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• 2003

In this paper, we propose a method that corrects the geometric distortion of mouth in an image. the method is composed of two steps - detecting key points and correcting geometric distortion. First, key points of lips in source and destination images are found by using lips detection algorithm. Then, the two images are mapped by using affine transformation and information found in first step. In experiment result for various mouths with different geometric distortion, we found that the proposed method have satisfactory efficiency.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.11a
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• pp.143-144
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• 2018

360 비디오는 VR 응용의 확산과 함께 몰입형 미디어로 주목 받고 있으며, JVET(Joint Video Experts Team)에서 post-HEVC 로 진행중인 VVC(Versatile Video Coding)에 360 비디오 부호화도 함께 고려하고 있다. 360 비디오 부호화를 위하여 변환된 2D 영상은 투영 면(face) 간의 불연속성과 비활성 영역이 존재할 수 있으며 이는 부호화 효율을 저하시키는 원인이 된다. 본 논문에서는 SSP(Segmented Projection)에서의 이러한 불연속성과 비활성 영역을 줄이는 효율적인 기하학적 패딩(padding) 기법을 제시한다. 실험결과 제안 기법은 복사에 의한 패딩을 사용하는 기존 SSP 대비 주관적 화질이 향상된 것을 확인 할 수 있었다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.5
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• pp.1357-1366
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• 1998

In this paper, we propose the method that extract shape features using the DCT(Discrete Cosine Transform) via simple invariant normalization. To retrieve effectively, we used measures, circularity and eccentricity, as filters to reduce the number of retrieved images. The experimental results show that our method is better than the methods of Fourier Descriptors and Moment Invariant for various leaf images.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.3
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• pp.224-239
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• 2013

An exact performance analysis of an ML detector for a 2-dimensional rotation-transform aided QPSK system operating over an impulsive noise environment is presented using Rieman integrals of a two-dimensional Gaussian Q-function over Voronoi cells. A set of interesting features of the Voronoi cells is also characterised systematically. An optimum rotation angle yielding the minimum BER is also studied. The differences between the proposed exact method and the previous approximate analysis method are investigated in terms of the corresponding BERs and the derived optimum angles.