• Journal of KIISE
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• v.42 no.2
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• pp.162-168
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• 2015

Image data is mostly stored in compressed form because of its huge size. Therefore, a series of cumbersome procedures is required to apply a transformation to image data: decompression, extraction of spatial data, transformation and recompression. In this paper, we employ DCT(Discrete Cosine Transform) coefficients to change the spatial presentation of images. DCT is commonly used in still image compression standards such as JPEG and moving picture compression standards such as MPEG-2, MPEG-4, and H.264. In this paper, we derived mathematically the relationship between the geometry transformation in the spatial domain and coefficient changes in the DCT domain and verified it with images in the JPEG file format. Because of the efficiency of transformation in the frequency domain, our findings can be utilized for light-weight partial image encryption for privacy data protection or entertainment contents protection.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.4
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• pp.67-75
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• 2011

This paper presents a scale and rotation-invariant gait recognition method using R-transform, which is computed by projecting squared coefficients of Radon transform. Since R-transform is invariant to translation, rotation, and scaling, it particularly suitable for extracting object poses without camera calibration. Coefficients of R-transform are used to compute correlation, and the maximum correlation value determines the similarity between two gait images. The proposed method requires neither camera calibration nor geometric compensation, and as a result, it makes robust gait recognition possible without additional compensation for translation, rotation, and scaling.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2561-2563
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• 2003

본 논문은 비-스플라인(B-spline) 보간법을 이용한 영상의 변환에 대하여 논한다. 국소적인 영상의 정보나 세분화된 영상의 정보를 얻기 위해 영상의 확대 변환이 필요하다. 본 논문에서는 영상의 확대 변환을 위해 선형 (linear), 큐빅 (cubic), 인근치 (nearest neighbour)등의 보간법 [2]과 비-스플라인(B-Spline) 보간법[1][3][4]을 적용하였다. 실험을 통하여 비-스플라인 보간법이 현재 많이 사용되고있는 인근치 보간법, 선형 보간법, 큐빅 보간법들 보다 상대적으로 우월한 영상의 질을 가져옴을 보였다. 결론적으로, 영상의 기하학적 변환에 있어 기존의 세 가지 보간법들 보다 비-스플라인 보간법을 사용한 경우에 더 좋은 결과를 가지며, 비-스플라인 함수의 차수가 고차로 갈수록 영상의 질이 향상됨을 알 수 있다. 렌즈 등에 의한 왜곡현상을 가지고 있는 위성 사진이나 의료 영상을 기하학적 변환을 통하여 보정하는데 비-스플라인 보간법을 적용할 수 있다.

• Communications of Mathematical Education
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• v.10
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• pp.293-302
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• 2000

GSP는 The Geometer's Sketchapd의 약자로 1994년 미국에서 연구 개발된 기하 프로그램이다. 기존의 정적인 평면 기하를 동적인 기하로 변환 할 수 있으므로 visual 세대인 현재의 학생들에게 학습에 대한 흥미를 유발시킬 수 있다. 본 논문에서는 특히 3차원 입체를 2차원 평면에 투영시키는 투시화법을 GSP를 도구로 구현해 보았다.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.4
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• pp.79-87
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• 2008

There has been a strong demand for low altitude UAV development in rapid mapping not only to acquire high resolution image with much more low cost and weather independent, compared to satellite surveying or traditional aerial surveying, but also to meet many needs of the aerial photogrammetry. Especially, efficient geocoding of UAV imagery is the key issue. Contrary to high UAV potential for civilian applications, the technology development in photogrammetry for example direct georeferencing is in the early stage and it requires further research and additional technical development. In this study, two approaches are supposed for automatic geocoding of UAV still images by simple affine transformation and block adjustment of affine transformation using minimal ground control points and also evaluated the applicability and quality of geometric model compared to geocoded images generated by commercial S/W.

• School Mathematics
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• v.14 no.3
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• pp.331-355
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• 2012

All the method used in teaching the ellipse was to have students draw the points which have the same sum of distances from the two points so that they can confirm the shapes of the ellipse before showing them the definition of ellipse. In this process, students would not get an opportunity to think or make the definition of ellipse for themselves. This deductive way can hinder students from having clear understanding of why such definition was made. This paper introduces a method of defining the ellipse based on the similarity between a circle and an ellipse, leading into the equation. This method is possible by introducing Analytic Geometry taught in current school mathematics and Transformation Geometry. By doing so, this paper will discuss a fundamental understanding about the ellipse and the feature of the ellipse expandable by intuition. Furthermore this paper will also show various advantages which can be given by defining the ellipse in Transformation Geometry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1465-1474
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• 1992

This paper describes a new overlapped object recognition method using extended local features. At first, we extract the extended local features consisting of corners, arcs, parallel-lines, and corner-arcs from the images consisting of model objects. Based on the extended local features we construct a knowledge-base. In order to match objects, we also extract the extended local features from the input image, and then check the compatibility between the extracted features and the features in the knowledge-base. From the set of compatible features, we compute geometric transforms. If any geometric transforms are clustered, we generate the hypothesis of the objects as the centers of the clusters, and then verify the hypothesis by a reverse geometric transform. An experiment shows that the proposed method increases the recognition rate and the accuracy as compared with existing methods.

• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.157-164
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• 2003

Volume graphics have received a lot of attention as a medical image analysis tool nowadays. In the visualization based on volume graphics, there is a process called voxelization which transforms the geometrically defined objects into the volumetric objects. It enables us to volume render the geometrically defined data with sampling data. This paper suggests a voxeliration method using the cutting surfaces of cubes, implements the method on a PC, and evaluates it with simple geometric modeling data to explore propriety of the method. This method features the ability of calculating the exact normal vector from a voxel, having no hole among voxels, having multi-resolution representation.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.6
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• pp.525-532
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• 2000

본 논문은 영상에서 형태적 정보를 추출하는데 사용되는 수학적 형태학(mathematical morphology)에 퍼지 집합 이론을 적용하여 새로운 퍼지 수학적 형태학을 제안한다. 일반적인 수학적 형태학은 이진 영상에만 적용되는 한계를 가지고 있었다. 이를 그레이 스케일 영상에도 적용 가능하도록 한 Sinha와 Dougherty[8]이 제안한 방법도 기하학적 형태 변환을 보장하지 못하는 결점이 있었는데 본 논문에서는 그 결점을 제거하는 새로운 수축(erosion)과 확장(dilation) 연산을 정의하고 그 특성을 연구하였다. 본 논문이 제안한 방법과 [8]의 방법을 실제 영상에 대한 실험으로 비교하였다.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.169-174
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• 2002

본 연구는 k개 지수분포 모수들의 기하평균에 대한 베이지안추정 방법을 제시하였다. 이를 위해 Tibshirani가 제안한 직교변환법으로 비정보적 사전확률분포를 도출하여 모수들의 결합사후확률분포를 유도해 내었으며, 이 분포 하에서 가중 몬테칼로 방법을 사용하여 기하평균을 추정하는 절차를 제안하였다. 모의실험과 실제자료의 예를 통해 제안된 베이지안 추정의 유효성 및 효용성을 보였으며, 본 연구에서 제안한 사전확률분포가 전통적인 포함확률을 기준으로 볼 때, Jeffrey의 사전확률분포 보다 더 유효한 추정을 함을 보였다.