• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.553-563
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• 1996

Detecting edges is one of issues with essentialimprotance in the area of image analysis. An edge in an image is a boundary or contour at which a significant change occurs in image intensity. Edge detection has been studied in many addlications such as imagesegmentation, robot vision, and image compression. In this paper, we propose an automatic threshold selection scheme for edge detection and show its application to noise elimination. The scheme suggested here applied statistical properties of the noise estimated from a noisy image to threshold selection. Since a selected threshold value in the scheme depends on not the characgreistic of an orginal image but the statistical feature of added noise, we can remove ad-hoc manners used for selecting the threshold value as well as decide the value theoretically. Furthermore, that shceme can reduce the number of edge pixels either generated or lost by noise. an application of the scheme to noise elimination is shown here. Noise in the input image can be eliminated with considering the direction of each edge pixedl on the edge map obtained by applying the threshold selection scheme proposed in this paper. Achieving significantly improved results in terms of SNR as well as subjective quality, we can claim that the suggested method works well.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.891-894
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• 2001

본 논문에서는 NTGST (noise·tolerant generalized symmetry transform)와 snake를 이용하여 복잡배경으로부터 여러 물체의 윤곽선을 동시에 검출하는 방법을 제안하였다. 먼저 NTCST의 대칭도 맵(symmetry map)을 이용하여 복잡한 배경에 혼재하는 여러 물체들의 위치를 찾은 다음, 이들 각 물체에 snake의 초기 윤곽들을 자동 설정해 줌으로써 기존 snake 알고리즘의 초기 윤곽 설정의 어려움과 다중 물체 윤곽선 검출의 어려움을 동시에 해결하였다. 이때 NTGST의 대칭도 맵으로부터 설정된 snake의 초기 윤곽은 실제 물체의 윤곽선 가까이에 위치할 뿐만 아니라 물체의 형태를 잘 반영하므로 요철이 있는 물체의 윤곽선도 기존의 방법보다 적은 반복횟수로 정확하게 검출 할 수 있다. 다양한 합성 영상과 실영상에 적용한 결과 복잡배경으로부터도 다중 물체의 윤곽선을 효과적으로 추출함을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.547-549
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• 2002

본 논문은 등고선을 이용한 입력된 지표면에 대하여, 소음 영향을 계산하는 프로그램 개발에 관한 것이다. 기존의 등고선 입력 방법을 구현하여 삼차원 지표면 입력을 받으며, 이것이 주위 환경의 일부이다. 삼차원 지표면 입력에 대하여, 국부에 대한 소음 영향을 예측하기 위하여, 지표면을 표현하는 다각형을 작은 삼각형으로 분리되며, 각 작은 삼각형에는 수음자들이 존재한다. 소음 원은 도로, 철도 등 다양하며, 소리가 퍼져나가는 근원이며, 모두 점 음원으로 간주된다. 지표면을 분리된 삼각형에 대하여 기하학 적인 방법을 사용하여 소음 전파 시뮬레이션이 이루어진다. 등고선 입력 방범은 저렴한 삼차원 지표면 입력 방범이며, 사용된 기하학 적인 소음 전파 영향 계산법은 제산 시간을 줄이면서 효율적으로 소음 영향을 예측할수 있게 해 준다.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.712-717
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• 2003

A novel multi-snake is proposed for efficient extraction of multi-object contours from a natural scene. An NTGST(noise-tolerant generalized symmetry transform) is used as a context-free attention operator to detect and locate multiple objects from a complex background and then the snake points are automatically initialized nearby the contour of each detected object using symmetry map of the NTGST before multiple snakes are introduced. These procedures solve the knotty subjects of automatic snake initialization and simultaneous extraction of multi-object contours in conventional snake algorithms. Because the snake points are initialized nearby the actual contour of each object, as close as possible, contours with high convexity and/or concavity can be easily extracted. The experimental results show that the proposed method can efficiently extract multi-object contours from a noisy and complex background of natural scenes.

• Journal of Korean Society of Rural Planning
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• v.30 no.3
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• pp.75-84
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• 2024

This study developed the procedure and method for the accuracy assessment of unmanned boat survey data, based on the reservoir water depth data of Misan Reservoir, measured by the manned and unmanned boats in 2009 by Korea Rural Community Corporation. In the first step, this study devised the method to extract the contour map of NGIS data in AutoCAD to generate easily the reservoir boundary map used to set the survey range of reservoir water depth and to test the survey accuracy. The surveyed data coordinate systems of the manned and the unmanned boat were also unified by using ArcGIS for the standards of accuracy assessment. In the accuracy assessment, the spatial correlation coefficient of the grid maps of the two measurement results was 0.95, showing high pattern similarity, although the average error was high at 78cm. To analyze in more detail assessment, this study generated randomly the 3,250m transverse profile route (PR), and then extracted grid values of water depth on the PR. In the results of analysis to the extracted depth data on PR, the error average difference of the unmanned boat measurements was 73.18cm and the standard deviation of the error was 55cm compared to the manned boat. This study set these values as the standard for the correction value by average shift and noise removal of the unmanned boat measurement data. By correcting the unmanned boat measurements with these values, this study has high accuracy results, the reservoir water depth and surface area curve with R² = 0.97 and the water depth and storage volume curve with R² = 0.999.

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.708-718
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• 2002

In this paper, the problems in identifying the noise sources by using the sound intensity technique are dealt with for the general radiated near-field from vibro-acoustic sources. For this purpose, a three-dimensional model structure resembling the engine room of a car or heavy equipment is considered. Similar to the practical situations, the model contains many mutually coherent and incoherent noise sources distributed on the complicated surfaces. The sources are located on the narrow, connected, reflecting planes constructed with rigid boxes, of which a small clearance exists between the whole box structure and the reflecting bottom. The acoustic boundary element method is employed to calculate the acoustic intensity at the near-field surfaces and interior spaces. The effects of relative source phases, frequencies, and locations are investigated, from which the results are illustrated by the contour map, vector plot, and energy streamlines. It is clearly observed that the application of sound intensity technique to the reactive or reverberant field, e.g., scanning over the upper engine room as is usually practiced, can yield the detection of fake sources. For the precise result for such a field, the field reactivity should be checked a priori and the proper effort should be directed to reduce or improve the reactivity of sound field.