• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.555-556
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• 2006

An experimental performance test has been carried out to improve a new blade with higher performance. Most of blades of the fan are designed to be a seamless and simple type, and the flow momentum can generally be evaluated to be comparatively low. Because some portions of the blowing winds can easily be passed through the seamless sharp edge of the blade, and several results studied on these problems have been reported: on the simple blade with edge-line seam, on the simple blade with guide seam. However the results do not show the remarkable increasement of performance of the blades. In this experimental performance test of the blades the design techniques of the blades with double seams (stem seam and edge seam) and comparison tests have been focused. As a first step the comparisons of velocity distributions and flow-rates depending upon the blade are presented in this paper.

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.542-548
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• 1997

In this study an evaluation method of fatigue strength of membrane type LNG tank is presented with FEM analysis and experimental approach of seam and raised edge welds. The study contains the following : l)FEM analysis of test specimens 2)Fatigue tests of seam and raised edge welds 3)Estimation of cumulative damage factor of the welds on the basis of safe life design concept complying with the rules of classification society 4)Review of the effect of mean stress on the fatigue strength 5)Modelling of fatigue life of the welds which is changeable by weld heights With the results obtained in this study, a model ${\Delta}{\delta}/h^2=0.13553\;{N_{f}}^{-0.3151}$ for seam and raised edge welds having a given weld height is proposed to be useful for designers and inspectors.

• Journal of Welding and Joining
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• 제18권3호
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• pp.60-67
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• 2000

In this study, we constructed a preview-sensing visual sensor system for weld seam tracking in GMA welding. The visual sensor consists of a CCD camera, a diode laser system with a cylindrical lens and a band-pass-filter to overcome the degrading of image due to spatters and/or arc light. To obtain weld joint position and edge points accurately from the captured image, we compared Hough transform method with central difference method. As a result, we present Hough transform method can more accurately extract the points and it can be applied to real time weld seam tracking. Image processing is carried out to extract straight lines that express laser stripe. After extracting the lines, weld joint position and edge points is determined by intersecting points of the lines. Although a spatter trace is in the image, it is possible to recognize the position of weld joint. Weld seam tracking was precisely implemented with adopting Hough transform method, and it is possible to track the weld seam in the case of offset angle is in the region of $\pm15^{\circ}$.

• 한국측량학회지
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• 제25권1호
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• pp.47-53
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• 2007

인공위성 영상을 이용하여 한반도 전역과 같이 넓은 지역에 대한 효율적인 영상 판독 및 분석 작업을 수행하기 위해서는 영상모자이크 작업이 필수적으로 요구된다. 본 논문은 영상모자이크 작업시 요구되는 접합선의 자동추출 기법과 이를 기반으로 한 자동 모자이크 영상제작 방법을 제시하였다. 인위적인 불연속을 최소화하는 접합선의 자동 추출기법으로는 검색영역에 대한 제약조건을 고려한 Minimum Absolute Gray Difference Sum 알고리즘과 Canny 에지검출 알고리즘을 함께 적용하였다. 또한 획득시기가 다른 인접영상간의 밝기 차이를 균일하게 유지시키기 위한 히스토그램 매칭 방법으로는 Match Cumulative Frequency 방법을 적용하였다. 본 연구의 결과 에지검출 기법을 통해 도로나 강 등과 같은 선형특성 지형 지물을 접합선으로 선정함으로서 인접영상간의 인위적인 불연속 형성을 최소화 할 수 있었다.

• 대한가정학회지
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• 제9권2호
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• pp.40-47
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• 1971

The purpose of this study was to examine the effects of several methods of the patching on the strength of the seam-texture. The main findings warranted from the present study were as follows : 1. The breaking strength was increased in proportion to the number of stitches in the case of 5 stitches per cm and 7 stitches per cm, not in the case of 9 stitches per cm where the tendency to damage the texture stitches appeared because of the excessive. 2. In comparing the effects of three methods (1. attaching a single patch, 2. attaching a single patch and seaming, 3. attaching several ply patch), no significant difference was found among these three. 3. There was a significant difference between the effects of two methods (1. attaching a single patch and stitching one edge of it on one side of the seam, 2. attaching a single patch and stitching both edges of it on the both sides of seam). In other words, the latter was found to be significantly more effective than the former. 4. In the case of unbalanced texture 9for example, single to two ply, single ply to two ply, or single to three ply), attaching a single patch to single ply and stitching both edges of it, and attaching a single patch to cover the plain-seam and stitching both edges of it, were more effective than attaching a single patch without stitching. 5. In comparing the effects of stitching both edges of the patch in 4 stitches per cm by the machine and by the hand, no significant difference was found. But these were more effective than stitching its both edges in 2 stitches per cm by hand. 6. The plain-seam stitched one edge of patch in 2 stitches per cm by machine and other by hand was significantly stronger than the plain-seam without a patch or with patch not stitched.

• 소성∙가공
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• 제18권1호
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• pp.52-58
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• 2009

Generally, a vertical rolling process is used to achieve extensive width reduction in hot strip mill. However, it is impossible to avoid the defects such as dog-bone and edge-seam defect. The sizing press process has been developed in response to the defects mentioned above. Especially, this study is carried out to investigate the deformation of slab by two-step sizing press. The deformation behavior of slab in the sizing press process is more favorable than that in conventional vertical rolling edger. The FE-simulation is applied to predict the deformation behavior of the slab. In this paper, the several causes of the asymmetrical deformation are mentioned for the purpose of understanding of the anvil shape. Load, dog-bone and edge-seam defect are discussed in width sizing process considering the anvil shape. And to reduce the problems generated at rougher mill just after sizing press, these are studied in this paper. The deformation behavior of slabs and optimum anvil shape are obtained by rigid-plastic finite element analyses and neural network.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.23-29
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• 2001

In this study, a preview-sensing visual sensor system is constructed far weld seam tracking in GMA welding. The visual sensor system consists of a CCD camera, a diode laser system with a cylindrical lens, and a band-pass-filter to overcome the degrading of image due to spatters and/or arc light. Among the image processing methods, Hough transform method is compared with the central difference method from a viewpoint of the capability for extracting the accurate feature position. As a result, it was revealed that Hough transform method can more accurately extract the feature positions and it can be applied to real time weld seam tracking. Image processing which includes Hough transform method is carried out to extract straight lines that express laser stripe. After extracting the lines, weld joint position and edge points are determined by intersecting the lines. Even though the image includes a spatter trace on it, it is possible to recognize the position of weld joint. Weld seam tracking was precisely implemented with adopting Hough transform method, and it is possible to track the weld seam in the case of offset angle is in the region of $\pm$ $15^{\circ}$.

• 방송공학회논문지
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• 제16권4호
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• pp.573-583
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• 2011

본 논문에서는 가상 시점 영상을 생성하는 과정에서 발생하는 가려짐 영역(occlusion region)을 보상하는 기법을 제안한다. 기존에 제안되었던 가려짐 영역 보상 기법들이 가려짐 영역이 발생한 주변 화소를 그대로 이용하거나, 평균값 또는 중간값을 이용하여 보상하기 때문에 시차의 분포 특성을 고려하기 어렵고 따라서 보상된 영역에서 시차의 정확성이 보장되지 않는다. 이러한 문제점들을 해결하기 위하여 본 논문에서는 에너지 편향치 또는 특징점 기반의 영상 크기 조절 방법인 심카빙(seam carving) 기법의 기본 원리를 응용하여 가려짐 영역을 보상하는 기법을 제안한다. 제안한 기법에서는 먼저 소벨 마스크(Sobel mask)를 사용해 영상의 에지 맵을 검출하고, 이진화 과정과 세선화 과정을 거친 후 심카빙 기법을 응용하여 원 영상과 세선화 된 에지 맵의 에너지 패턴을 구한다. 구한 에너지 패턴으로 가려짐 영역을 보상하게 된다. 다양한 영상에 적용하여 제안된 기법의 성능을 실험하였고, 그 결과 기존의 보상 방법에 비해 영상의 중요 정보를 손상시키지 않고 가려짐 영역을 비교적 정확하게 보상하는 것을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.437-438
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• 2006

Generally, the vertical roll process is used to achieve extensive width reduction in hot strip mill. However, it is difficult to avoid the defects such as dog-bone and seam-defect. The sizing press has been developed in response to the defects mentioned above. Especially, this study is carried out to investigate the deformation of slab by two-step sizing press. The deformation behavior in the width sizing process is more favorable than that in conventional vertical rolling edger. The objective of this study is to determine the optimal anvil shape parameters in the sizing press with two-step die from the viewpoint of edge-seam length. In general, the edge-seam defect occurs parallel to the rolling direction at both edges in horizontal rolling process after sizing press. The optimal combination of the parameters is determined by FE-simulation and Artificial Neural Network (ANN). The slab deformation in sizing press with convex anvil is analyzed by FE-simulation. The most suitable profile of the anvil is also discussed fur the improvement of trimming loss because of the side seam defect by FE-simulation and ANN.

• 대한산업공학회지
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• 제18권2호
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• pp.83-97
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• 1992

A new approach, to seam tracking for robotic are welding is proposed. In this approach, the weld model is a snapshot image and the acquired image is analyzed and compared to the welding database which contains CAD data, weld positions, weld parameters, etc. This paper presents a fast and robust algorithm for the Hough Transform. This modified Hough Transform(MHT) algorithm uses the least-squares regression analysis method in order to approximate the edge lines more precisely, and leads to a significant reduction in both computation and storage. In comparison with the conventional seam tracking methods, this new approach has the advantages of low cost, continuous welding, and various type welding.