• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.651-656
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• 2001

Histogram intersection method, that counts the occurrence of color pixels, is one of the easy and simple color image retrieval methods. The method has an appropriate global property but does not contain the knowledge of shape for images. The absence of spatial information makes it difficult to discriminate images of the similar histogram. The application of one-dimensional projection to each image enables to obtain shape or spatial information of image. But in this case there is another problem having different length of the projection vector according to the size of each image. Thus this paper proposes a method that uses relative distances between peaks and their maximum value in the projection vector. In order to verify retrieval performance, the experimental results between the histogram intersection method, the projection only method, and the proposed one are compared and analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.191-199
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• 1993

Investigation is given to the detailed procedure of a computer assisted automatic technique for ortho-image generation from digital stereo image data of close-range photographs scanned by the CCD camera scanner. After rectification of geometric scanning errors, the bundle adjustment technique was used to determine the exterior orientation parameters of terrestrial camera. An automatic correlation matching technique was applied to search for the conjugate pixels in digital stereo pairs. And the 3-dimensional coordinates of the corresponding pixels were calculated by the space intersection method. For the generation of ortho-image from the calculated coordinates and right image data values, inverse-weighted-distance average method was used. And the accuracy of the resulting ortho-image was checked by comparing its image coordinates with there corresponding ground coordinates for the check points.

• Solar Energy
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• v.13 no.2_3
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• pp.37-44
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• 1993

건물의 외부에 차양을 설치하는 것은 건물이 갖는 냉방부하를 줄일 수 있는 중요한 요인이 된다. 외부차양의 효율성은 차양의 형태, 크기, 태양의 경로, 건물의 방향등과 같은 요소에 의해 결정 지어진다. 그러나, 이러한 요소들이 서로 동적으로 상호 관련 되어 있기 때문에 외부차양에 의한 그림자 투영은 예측하기 힘들고, 따라서 냉방부하가 얼마만큼 감소되는지는 더욱더 예측이 어려워진다. 이 논문은 디자이너가 직접 외부차양을 컴퓨터 그래픽으로 디자인 함과 동시에 그림자 투영을 시각화 할 수 있는 프로그램 개발을 위한 연구이다.

• Journal of Korea Water Resources Association
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• v.57 no.8
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• pp.549-559
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• 2024

This study aims to investigate the feasibility of using image analysis methods to examine the flow characteristics of air bubbles discharged underwater. A bubble screen was created using multiple nozzles in a laboratory flume filled with stagnant water. The flow characteristics of the bubbles were analyzed, and the suitability of the analysis method was evaluated. Several parameters, such as projection area ratio and depth ratio, were defined to conduct laboratory experiments and analyze the flow characteristics of the bubbles. Correlation and regression analyses were performed to assess the relationships between various variables. Specifically, the correlation between the bubble's projection area and its rising speed across eight water depth ratios was examined. The results indicated that as the depth ratio increased, the bubble size exhibited a linear increase with a strong correlation as it rose to the water surface due to pressure effects. Regarding the sensitivity of different grid sizes in the ten analysis grids when applying image analysis methods, it was observed that the sensitivity to grid size based on the projection area ratio (0.09~0.96) was not significant. These findings suggest that image analysis techniques can be effectively utilized to observe the flow characteristics of bubbles.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.903-906
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• 2001

본 논문에서는 조명의 변화에 의해 컬러 영상의 컬러 성분이 달라지더라도 영상 내 컬러간의 편차값을 나타내는 공분산 행렬(covariance matrix)의 고유벡터(eigenvector)와 영상 내 화소들의 컬러 성분과의 상관관계는 거의 변화하지 않는 특징을 이용한 조명 변화에 강인한 영상 검색 방법을 제안한다. 제안된 방법은 영상에서 컬러 성분들의 공분산 행렬과 공분산 행렬의 고유치(eigenvalue), 고유벡터를 계산한 후, 가장 큰 고유치에 관계된 고유벡터로 화소를 투영시키고, 투영된 벡터의 크기 성분으로 영상을 재구성한다. 재구성된 영상으로부터 7개의 불변 모멘트(moment)를 계산하고, 공분산의 가장 큰 고유치를 가중치로 부과하여 특징벡터를 추출한다. 7개의 불변 모멘트로부터 구한 특징벡터는 영상 내 물체의 이동, 영상의 회전, 크기 변화뿐만 아니라, 조명의 변화에 의해 컬러가 변화할 경우에도 유사한 영상을 잘 검색한다. 제안된 방법의 성능 확인을 위하여 5가지 조명에서 얻은 영상 데이터베이스를 이용하여 실험하였으며, 실험 결과 히스토그램 인터섹션에 비해 적은 특징량으로 검색이 가능하면서 조명 변화에도 대응할 수 있는 검색 결과를 얻을 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.927-930
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• 2000

본 논문은 문서 영상에 대해 투영을 사용하여 영역을 나누었고 각 영역에 대해 고주파 밴드의 웨이블렛 계수의 통계적 분산과 히스토그램을 기반으로 한 두 가지 특징을 사용하여 문자와 그림으로 분류하였다. 투영으로 나누어진 영역들에 대해 일정 크기의 블록으로 나누고 두 가지 특징에 따라 문자와 그림으로 분류하였다. 따라서 투영에 의해 나뉜 영역 중 문자와 그림이 혼합되어 의미가 모호한 영역에 대해 잘못 분류되는 가능성을 줄일 수 있었다.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.99-106
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• 2006

Type classification is a very needed step in recognizing huge character set language such as korean characters. Since most previous researches are based on the composition rule of Korean characters, it has been difficult to correctly classify composite vowel characters and problem space was not divided equally for the lack of classification of last consonant which is relatively bigger than other graphemes. In this paper, I Propose a new type classification method in which horizontal vowel is extracted before vortical vowel and last consonants are further classified into one of five small groups based on horizontal projection profile. The new method uses 19 character types which is more stable than previous 6 types or 15 types. Through experiments on 1.000 frequently used character sets and 30.614 characters scanned from several magazines, I showed that the proposed method is more useful classifying Korean characters of huge set.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.357-364
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• 2014

The filtered back projection in the image reconstruction algorithms for the clinic computed tomography system has been widely used. Noise of the reconstructed image was examined under the input noise for parallel and fan beam geometries. The reconstruction images of $512{\times}512$ size were carried out under 360 and 720 projection by the Visual C++ for parallel beam and fan beam, respectively, and those agreed with the original Shepp-Logan head phantom very much. Noise was generated because of intrinsic restriction (finite number of projections) for the image reconstruction algorithm, filtered back projection, when no input noise was applied. Because the result noise was rapidly increased under 0.5% input noise ratio, technologies for reducing noise in CT system and image processing is important.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.2
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• pp.119-126
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• 1996

TM projection is widely used for surveying and mapping. However, the complicated computations and process are required and, moreover. the different results of computation may occur according to different formulae and coefficients. In this study, the transformation formulae are classified into 4 categories and the computations are executed according to the categories. The computations are also made to different value of the circular constant, $\pi$. The result of test shows that the enough number of items in formular have to be used for precise computation and the circular constant has to calculate down the 13 places of decimals in order to obtain the precision of 1mm on the ground scale.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.182-188
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• 2002

We have analyzed the phase-calculation-error of a three-dimensional shape measurement system using the projection of phase shifted fringe patterns. In this study, we have dealt various errors; an error caused by the variation of quantization levels, an error caused by the defocus of fringe pattern projected images, an error caused by phase-shifting errors, an error caused by the intensity variation of the background and modulation amplitude of fringe pattern projected images during the projection of multiple patterns, an error caused by the distortion of sinusoidal shape of a fringe pattern. The results will contribute to the design of a three-dimensional shape measurment system and give an important meaning to the calculation and the analysis of the accuracy of a system.