• Journal of the Korea Computer Graphics Society
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• v.4 no.1
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• pp.55-66
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• 1998

This paper presents a simple method for relieving the ambiguity problems within the sub-voxel based surface-fitting approach for the surface construction. ECB algorithm is proposed to avoid the ambiguity problem which is the root of the holes within the resulting polygon based approximation. The basic idea of our disambiguation strategy is the use of a set of predefined modeling primitives (we call SMP) which guarantees the topological consistency of resulted surface polygons. 20 SMPs are derived from the extension of the concept of the elementary modeling primitives in the CB algorithm [3], and fit one to five faces of them to the iso-surface crossing a cell with no further processing. A look-up table which has a surface triangle list is pre-calculated using these 20 SMPs. All of surface triangles in the table are from the faces of SMPs and are stored in the form of edge list on which vertices of each surface triangle are located. The resulted polygon based approximation is unique at every threshold value and its validity is guaranteed without considering the complicated problems such as average of density and postprocessing. ECB algorithm could be free from the need for the time consuming post-processing, which eliminates holes by revisiting every boundary cell. Through three experiments of surface construction from volume data, its capability of hole avoidance is showed.

• The KIPS Transactions:PartA
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• v.10A no.5
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• pp.425-432
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• 2003

This paper presents an EMR(Electronic Medical Record) chart for efficient PDA through the quad tree image rendering based on the mobile. Using the intermediate image space algorithm instead of the final one for volume rendering, we have solved the probems of th eholes coming from the point-to-point to mapping. The quad-tree based on the delta-tree efficiently represents volume expressions and results in higher compression effects. With the volume rendering, we can decrease the rendering time and get a higher quality and efficiency for PDA through image based rendering.

• Design & Manufacturing
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• v.12 no.2
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• pp.46-50
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• 2018

Recently, as machine components and products are getting smaller, it is demanded to develop superprecision production technologies multilaterally. Along with the advancement of production technology, people are paying keener attention to the development of eco-friendly technology and efficient processing technology. Particularly, in many industries related to automobiles, shipbuilding, or airplane components, it is demanded to obtain technology to process multiple micro-holes. On account of this trend, micro-hole processing employing high-power electron beams is rising nowadays, and more interest is being shown in it, too. In Korea, however, the process of manufacturing vaporized amplification sheets influencing high-power electron beam processing technology and the processability considerably has not been developed sufficiently yet. Therefore, this study has applied vaporized amplification sheets manufactured to analyze the processability of high-power electron beams and examine necessity for vaporized amplification sheets.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.239-242
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• 2009

Friction stir spot welding (FSSW), developed based on principle of friction stir welding, has been paid attention as a new solid-state spot welding process. Since FSSW can produce high-quality weld in Al alloys more easily than resistance spot welding, this process has been already used for construction of Al components in the automotive industries. Despite the large industrial interests in FSSW, fundamental knowledge on welding phenomena of this process has not been fully understood. In this study, FSSW phenomena, such as the consolidation mechanism, the microstructural evolution and the material flow, were examined in Al alloy 6061. This study clarified that the elliptical zone found in the vicinity of the pin hole on the cross section was characterized by the initially lapped surface of two sheets. Moreover, the following material flow was proposed; capture of the upper material with the threads on the pin surface, spiral flow along the tool rotation, and then release at the tip of the pin.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.12
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• pp.4866-4888
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• 2020

One major and time-consuming task in fish production is obtaining an accurate estimate of the number of fish produced. In most Nigerian farms, fish counting is performed manually. Digital image processing (DIP) is an inexpensive solution, but its accuracy is affected by noise, overlapping fish, and interfering objects. This study developed a catfish recognition and counting algorithm that introduces detection before counting and consists of six steps: image acquisition, pre-processing, segmentation, feature extraction, recognition, and counting. Images were acquired and pre-processed. The segmentation was performed by applying three methods: image binarization using Otsu thresholding, morphological operations using fill hole, dilation, and opening operations, and boundary segmentation using edge detection. The boundary features were extracted using a chain code algorithm and Fourier descriptors (CH-FD), which were used to train an artificial neural network (ANN) to perform the recognition. The new counting approach, based on the geometry of the fish, was applied to determine the number of fish and was found to be suitable for counting fish of any size and handling overlap. The accuracies of the segmentation algorithm, boundary pixel and Fourier descriptors (BD-FD), and the proposed CH-FD method were 90.34%, 96.6%, and 100% respectively. The proposed counting algorithm demonstrated 100% accuracy.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1025-1034
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• 2022

In this paper, we propose a post-processing method through interpolation of hole regions that occur when extracting point clouds. When image matching is performed on stereo image data, holes occur due to occlusion and building façade area. This area may become an obstacle to the creation of additional products based on the point cloud in the future, so an effective processing technique is required. First, an initial point cloud is extracted based on the disparity map generated by applying stereo image matching. We transform the point cloud into a grid. Then a hole area is extracted due to occlusion and building façade area. By repeating the process of creating Triangulated Irregular Network (TIN) triangle in the hall area and processing the inner value of the triangle as the minimum height value of the area, it is possible to perform interpolation without awkwardness between the building and the ground surface around the building. A new point cloud is created by adding the location information corresponding to the interpolated area from the grid data as a point. To minimize the addition of unnecessary points during the interpolation process, the interpolated data to an area outside the initial point cloud area was not processed. The RGB brightness value applied to the interpolated point cloud was processed by setting the image with the closest pixel distance to the shooting center among the stereo images used for matching. It was confirmed that the shielded area generated after generating the point cloud of the target area was effectively processed through the proposed technique.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.3
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• pp.173-178
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• 2024

This study presents a technique for assessing the dimensional quality of assembly parts in Prefabricated Steel Structures (PSS) using a stereo vision sensor. The stereo vision system captures images and point cloud data of the assembly area, followed by applying image processing algorithms such as fuzzy-based edge detection and Hough transform-based circular bolt hole detection to identify bolt hole locations. The 3D center positions of each bolt hole are determined by correlating 3D real-world position information from depth images with the extracted bolt hole positions. Principal Component Analysis (PCA) is then employed to calculate coordinate axes for precise measurement of distances between bolt holes, even when the sensor and structure orientations differ. Bolt holes are sorted based on their 2D positions, and the distances between sorted bolt holes are calculated to assess the assembly part's dimensional quality. Comparison with actual drawing data confirms measurement accuracy with an absolute error of 1mm and a relative error within 4% based on median criteria.

• Journal of Veterinary Clinics
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• v.8 no.2
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• pp.183-190
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• 1991

Pellet and straw methods in canine semen freezing are compared with respect to motility, viability and acrosome demage of sperm during each of the two major processing steps, to prior-freezing and to frozen-thawing. Senen was extended with a tris-buffered egg yolk contained 4% glycero1 Pellet freezing in the hole of dry ice and straw freezing on the surface of liquid nitrogen were carried out, respectively. The frozen semen 10 days after storage in liquid nitrogen container. wao thawed. In the comparison of two freezing methods, the straw freezing method with 42.7% in motility. 49.2% in viability and 0.186 acrosome score after thawing seems to be superior to the pellet freezing method with 31.2%, 34.5% and 0.314%, respectively. Sperm motility of processing step to frozen-thawing against decrease rate 12.67% to Prior freezing appeared of 33.84% and 49.37% in straw and pellet freezing and increase of 0.02 in acrsomal score to prior freezing appeared of 0.08 and 0.21 in straw and pellet freezing method to frozen-thawing

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.5
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• pp.471-477
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• 2015

In this study, the property of crack propagation and growth at high tension steel plate existed with center crack is investigated. The behaviors of fracture mechanics due to existence or not of hole near the center crack in specimen and the length of crack length are investigated when the load is applied at the one side end of specimen. Stress, deformation and deformation of this specimen are evaluated through simulation analysis. By the analysis results at this study, stress intensity factors are obtained. The damage happened at machine or structure with crack or defect can be estimated on the basis of study results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.784-795
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• 1995

This paper represents the results of the experiments of the three-dimensional flow and the aerodynamic loss caused by the three-dimensional flow within the plane bucket blades. To research the secondary flow and the aerodynamic loss, the large-scale plane bucket blade of lst-stage in the low pressure steam turbine is made of FRP. The detailed investigation of the secondary flow and the aerodynamic loss using 5-hole pressure probe within turbine cascade has been carried out in the low speed wind tunnel. The limiting streamlines of the suction and endwall surface have been visualized by the oil film method. The flow visualization of the secondary flow has been performed by the laser light sheet technique and image processing system. By using the method mentioned above, it is possible to observe the evolution of the pitchwise mass-averaged flow deviation angle and total pressure loss coefficient, the secondary flow, and the aerodynamic loss through the cascade.