• Clinics in Shoulder and Elbow
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• v.18 no.4
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• pp.211-216
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• 2015

Background: Few studies have investigated magnetic resonance (MR) characteristics of traumatic posterosuperior rotator cuff tears involving the supraspinatus and infraspinatus. We hypothesized that traumatic rotator cuff tears may have MR characteristics distinguishable from those of non-traumatic tears. Methods: Preoperative MR arthrography and intraoperative tear size measurements were compared in 302 patients who underwent MR arthrography and subsequent arthroscopic rotator cuff repairs for traumatic (group T, 61 patients) or non-traumatic (group NT, 241 patients) tears. The inclusion criteria for both groups were posterosuperior full-thickness rotator cuff tear and age between 40 and 60 years. For group T, traumas were limited to accidental falls or slips, or sports injuries, motor vehicle accidents; injuries were associated with acute onset of pain followed by functional shoulder impairment; and time between injury and magnetic resonance imaging (MRI) was 6 weeks or less. Results: In group T, 72.1% of shoulders (44 patients) had tendon tears with blunt edges while 27.9% of shoulders (17 patients) had tears with tapering edges. In contrast, 21.2% of patients in group NT (51 patients) had blunt-edge tears, while 78.8% (190 patients) of tears had tapering edges. These results were statistically significant (p<0.001) and estimated odds ratio was 9.6. The size of tear did not vary significantly between groups. Conclusions: We found no exclusive MR characteristic to define traumatic tears. However, oblique coronal MRI of traumatic tears showed a significant tendency for abrupt and rough torn tendon edges and relatively consistent tendon thicknesses (without lateral tapering) compared to non-traumatic cuff tears.

• Journal of the Korea Computer Graphics Society
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• v.12 no.4
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• pp.7-15
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• 2006

The ultimate objective of painterly rendering is to express an inputted image as if it is hand drawn. The factors to express this painterly effect are thickness of the brush, direction, texture and the establishment of criteria judging if the produced brush will be drawn on to the canvas. In this paper, the algorithm using density of the edges in determining the criteria whether the brush will be drawn onto the canvas is proposed. Density of edges refers to the quantity of edge in the specific area. And uses the method of finding the location of the brush to be drawn as a unit of dynamic grid as well as expressing consistent directional through direction interpolation. Also, the texture is expressed using various textured brushes. Considering density of edges,We can express detailed area and abstract area. And it result in more human effect of oil painting.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.83-86
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• 1996

In this paper we study the problem of augmenting a physical network to improve the topology for new survivable network architectures. We are given a graph G=(V,E,F), where V is a set of nodes that represents transmission systems which be interconnected by physical links, and E is a collection of edges that represent the possible pairs of nodes between which a direct transmission link can be placed. F, a subset of E is defined as a set of the existing direct links, and E/F is defined as a set of edges for the possible new connection. The cost of establishing network $N_{H}$=(V,H,F) is defined by the sum of the costs of the individual links contained in new link set H. We call that $N_{H}$=(V,H,F) is feasible if certain connectivity constrints can be satisfied in $N_{H}$=(V,H,F). The computational goal for the suggested model is to find a minimum cost network among the feasible solutions. For a k edge (node) connected component S .subeq. F, we charactrize some optimality conditions with respect to S. By this characterization we can find part of the network that formed by only F-edges. We do not need to augment E/F edges for these components in an optimal solution. Hence we shrink the related component into a node. We study some good primal heuristics by considering construction and exchange ideas. For the construction heuristics, we use some greedy methods and relaxation methods. For the improvement heuristics we generalize known exchange heuristics such as two-optimal cycle, three-optimal cycle, pretzel, quezel and one-optimal heuristics. Some computational experiments show that our heuristic is more efficient than some well known heuristics.stics.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.123-131
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• 2005

Among the digital halftoning, the error diffusion halftoning gives better subjective quality than other halftoning techniques. But it also makes edges of objects blurred. To overcome the defect, this paper proposes the modified error diffusion halftoning algorithm to enhance the edges using the spatial perceptual properties of the human visual system. Using the properties that the human eyes perceive not the pixel's luminance itself but the local average luminance and the information that human eyes perceive spatial variation, the proposed method computes information of edge enhancement(IEE). The IEE is added to the quantizer's input pixel and feeds into the halftoning quantizer. The quantizer produces the halftone image having the enhanced edge. Also this paper proposes the technique that the coefficients of the error diffusion filter are adapted according to the correlation among color components. The computer simulation results show that the proposed method produces finer halftoning images than conventional methods due to the enhanced edges. And the proposed method also preserves similar in edges to original image and reduces some defects such as color impulse and false contours.

• Journal of the Korean Mathematical Society
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• v.48 no.1
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• pp.105-115
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• 2011

Let f be a function which assigns a positive integer f(v) to each vertex v $\in$ V (G), let r, s and t be non-negative integers. An f-coloring of G is an edge-coloring of G such that each vertex v $\in$ V (G) has at most f(v) incident edges colored with the same color. The minimum number of colors needed to f-color G is called the f-chromatic index of G and denoted by ${\chi}'_f$(G). An [r, s, t; f]-coloring of a graph G is a mapping c from V(G) $\bigcup$ E(G) to the color set C = {0, 1, $\ldots$; k - 1} such that |c($v_i$) - c($v_j$ )| $\geq$ r for every two adjacent vertices $v_i$ and $v_j$, |c($e_i$ - c($e_j$)| $\geq$ s and ${\alpha}(v_i)$ $\leq$ f($v_i$) for all $v_i$ $\in$ V (G), ${\alpha}$ $\in$ C where ${\alpha}(v_i)$ denotes the number of ${\alpha}$-edges incident with the vertex $v_i$ and $e_i$, $e_j$ are edges which are incident with $v_i$ but colored with different colors, |c($e_i$)-c($v_j$)| $\geq$ t for all pairs of incident vertices and edges. The minimum k such that G has an [r, s, t; f]-coloring with k colors is defined as the [r, s, t; f]-chromatic number and denoted by ${\chi}_{r,s,t;f}$ (G). In this paper, we present some general bounds for [r, s, t; f]-coloring firstly. After that, we obtain some important properties under the restriction min{r, s, t} = 0 or min{r, s, t} = 1. Finally, we present some problems for further research.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.63-69
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• 2012

Given art gallery P with n vertices, the maximum (sufficient) number of mobile guards is${\lfloor}n/4{\rfloor}$ for simple polygon and${\lfloor}(3n+4)/16{\rfloor}$ for simple orthogonal polygon. However, there is no polynomial time algorithm for minimum number of mobile guards. This paper suggests polynomial time algorithm for the minimum number of mobile guards. Firstly, we obtain the visibility graph which is connected all edges if two vertices can be visible each other. Secondly, we select vertex u with ${\Delta}(G)$ and v with ${\Delta}(G)$ in $N_G(u)$ and delete visible edges from u,v and incident edges. Thirdly, we select $w_i$ in partial graphs and select edges that is the position of mobile guards. This algorithm applies various art galley problems with simple polygons and orthogonal polygons art gallery. As a results, the running time of proposed algorithm is linear time complexity and can be obtain the minimum number of mobile guards.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.709-713
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• 2005

A new algorithm is proposed for the extraction of line segments to construct 3D wire-frame models of building from the high-resolution aerial images. The purpose of this study Is the accurate and effective extraction of line segments, considering the problems such as discordance of lines and blurred edges existing in the conventional methods. Using the edge map extracted from aerial images, chain code tracking of edges was performed. Then, we extract the line segments considering the strength of edges and the direction of them. SUSAN (Smallest Uni-value Segment Assimilating Nucleus) algorithm proposed by Smith was used to extract an edge map. The proposed algorithm consists of 4 steps: removal of the horizontal, vertical and diagonal components of edges to reduce non-candidate point of line segments based on the chain code tracking of the edge map, removal of contiguous points, removal of the same angle points, and the extraction of the start and end points to be line segments. By comparing the proposed algorithm with Boldt algorithm, better results were obtained regarding the extraction of the representative line segments of buildings, having relatively less extraction of unnecessary line segments.

• Tunnel and Underground Space
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• v.27 no.2
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• pp.109-119
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• 2017

A lot of twin tunnels were modelled with different pillar widths, rock mass classes and stress ratios in order to consider various site conditions, and the stabilities of the pillars were estimated by numerical analyses and scaled model tests. The strength-stress ratios of the pillar were obtained from three different methods which were using the stresses appeared at the middle point, the whole average and the left/right edges of the pillar. The strength-stress ratio of the pillar edges showed relatively conservative values among them, and it was also practically consistent with the tunnel excavating steps comprising the construction sequence analyses which included the partial excavation and the support system. Scaled model tests were also performed to investigate the tunnel stability, where it was found that cracks were progressively generated from the pillar edges toward the middle point of the pillar. Therefore, in order to both prevent the local damage of pillar and conservatively estimate the tunnel stability, it was thought to be an appropriate method using the strength-stress ratio obtained from the left/right edges of the pillar.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.645-650
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• 2010

In this paper, we present the effect of binocular cues which plays crucial role for the visualization of a stereoscopic or 3D image. This study is useful in extracting depth and disparity information by image processing technique. A linear relation between the object distance and the image distance is presented to discuss the cause of cybersickness. In the experimental results, three dimensional view of the depth map between the 2D images is shown. A median filter is used to reduce the noises available in the disparity map image. After the median filter, two filter algorithms such as 'Gabor' filter and 'Canny' filter are tested for disparity visualization between two images. The 'Gabor' filter is to estimate the disparity by texture extraction and discrimination methods of the two images, and the 'Canny' filter is used to visualize the disparity by edge detection of the two color images obtained from stereoscopic cameras. The 'Canny' filter is better choice for estimating the disparity rather than the 'Gabor' filter because the 'Canny' filter is much more efficient than 'Gabor' filter in terms of detecting the edges. 'Canny' filter changes the color images directly into color edges without converting them into the grayscale. As a result, more clear edges of the stereo images as compared to the edge detection by 'Gabor' filter can be obtained. Since the main goal of the research is to estimate the horizontal disparity of all possible regions or edges of the images, thus the 'Canny' filter is proposed for decipherable visualization of the disparity.

• Journal of KIISE:Information Networking
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• v.31 no.3
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• pp.298-304
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• 2004

In transmitting a compressed video bit-stream over Internet, a packet loss causes an error propagation in both spatial and temporal domain, which in turn leads to a severe degradation in image quality. In this paper, a new error concealment algorithm is proposed to repair damaged portions of the video frames in the receiver. Conventional BMA(Boundary Matching Algorithm) assumes that the pixels on the boundary of the missing block and its neighboring blocks are very similar, but has no consideration of edges t)r discontinuity across the boundary. In our approach, the edges are detected across the boundary of the lost or erroneous block. Once the edges are detected and the orientation of each edge is found, only the pixel difference along the expected edges across the boundary is measured instead of calculating differences between all adjacent pixels on the boundary. Therefore, the proposed approach needs very few computations and the experiment shows an improvement of the performance over the conventional BMA in terms of both subjective and objective quality of video sequences.