• Honam Mathematical Journal
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• v.36 no.4
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• pp.787-794
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• 2014

We prove three convex hull theorems on triangles and circles. Given a triangle ${\triangle}$ and a point p, let ${\triangle}^{\prime}$ be the triangle each of whose vertices is the intersection of the orthogonal line from p to an extended edge of ${\triangle}$. Let ${\triangle}^{{\prime}{\prime}}$ be the triangle whose vertices are the centers of three circles, each passing through p and two other vertices of ${\triangle}$. The first theorem characterizes when $p{\in}{\triangle}$ via a distance duality. The triangle algorithm in [1] utilizes a general version of this theorem to solve the convex hull membership problem in any dimension. The second theorem proves $p{\in}{\triangle}$ if and only if $p{\in}{\triangle}^{\prime}$. These are used to prove the third: Suppose p be does not lie on any extended edge of ${\triangle}$. Then $p{\in}{\triangle}$ if and only if $p{\in}{\triangle}^{{\prime{\prime}}$.

• International Journal of Highway Engineering
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• v.19 no.3
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• pp.71-81
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• 2017

PURPOSES : In this study, the effects of installation of diagonal crosswalks on traffic flow depending on the types of intersections are analyzed. METHODS : Scrambled crosswalks have advantages in the traffic safety. Therefore, a comparative analysis of the overall average delay before and after installation of the scrambled crosswalk was conducted using VISSIM. RESULTS : The overall average delay for the scrambled crosswalk decreased when the traffic volume ratio of the major to the minor street is 1: 6 in 2-by-1 and 3-by-1 types of intersections. The scrambled crosswalk improved efficiency of traffic operation in intersections: higher traffic volume for a major street, lower traffic volume for a minor street, and longer cross-distance for a major street. CONCLUSIONS:This study can be used to determine when a scrambled crosswalk should be installed to improve operational efficiency.

• Journal of information and communication convergence engineering
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• v.14 no.4
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• pp.215-221
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• 2016

We consider a design of a combined quantizer and estimator for distributed systems wherein each node quantizes its measurement without any communication among the nodes and transmits it to a fusion node for estimation. Noting that the quantization partitions minimizing the estimation error are not independently encoded at nodes, we focus on the parameter regions created by the partitions and propose a cluster-based quantization algorithm that iteratively finds a given number of clusters of parameter regions with each region being closer to the corresponding codeword than to the other codewords. We introduce a new metric to determine the distance between codewords and parameter regions. We also discuss that the fusion node can perform an efficient estimation by finding the intersection of the clusters sent from the nodes. We demonstrate through experiments that the proposed design achieves a significant performance gain with a low complexity as compared to the previous designs.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.55-59
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• 1990

This study presents new algorithm for generating octree by volume intersection with pseudo-octrees which are constructed for each orthogonal face views in order to represent 3D objects exactly. In this algorithm, optimal quadtree is constructed for depth images in which distance information is represented in gray level, and then pseudo-octrees are constructed by using optimal quadtree in each orthogonal face view. It is shown that 3D object with concave parts can be reconstructed exactly by our suggested algorithm, and that memory space and tree construction time are also reduced compared with other algorithms.

• Journal of KIISE:Software and Applications
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• v.26 no.1
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• pp.150-150
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• 1999

In this paper, a content-based image retrieval scheme based on scale-space theory is proposed. The existing methods using scale-space theory consider all scales for image retrieval,thereby requiring a lot of computation. To overcome this problem, the proposed algorithm utilizes amodified histogram intersection method to select candidate images from database. The relative scalebetween a query image and a candidate image is calculated by the ratio of histograms. Feature pointsare extracted from the candidates using a corner detection algorithm. The feature vector for eachfeature point is composed of RGB color components and differential invariants. For computing thesimilarity between a query image and a candidate image, the euclidean distance measure is used. Theproposed image retrieval method has been applied to various images and the performance improvementover the existing methods has been verified.

• Proceedings of the ESK Conference
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• 1996.04a
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• pp.36-47
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• 1996

By integrating the eye head-position monitioring devices, the present authors developed an eye-controlled human/computer interface based on the line-of-sight and an intentional blink to invoke commands. Also modified was an existing calibration method to reduce the visual angle between the target center and the intersection point of the derived line-of-sight. This modified calibration method allowed 108 or more command blocks to be displayed on the 14 inch monitor with the target acquisition probability(hit rate) of 98% when viewed at the distance of 500 mm apart. An active triggering method using an intentional blink was proposed and was shown to be a feasible and efficient alternative to invoke commands with total triggering time of 0.8 sec or less. The system could be used by the normal people as well as the handicapped individuals as a new human/computer interface.

• Smart Structures and Systems
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• v.32 no.2
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• pp.111-121
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• 2023

This study proposes an automated assembly performance evaluation method for prefabricated steel structures (PSSs) using machine learning methods. Assembly component images were segmented using a modified version of the receptive field pyramid. By factorizing channel modulation and the receptive field exploration layers of the convolution pyramid, highly accurate segmentation results were obtained. After completing segmentation, the positions of the bolt holes were calculated using various image processing techniques, such as fuzzy-based edge detection, Hough's line detection, and image perspective transformation. By calculating the distance ratio between bolt holes, the assembly performance of the PSS was estimated using the k-nearest neighbors (kNN) algorithm. The effectiveness of the proposed framework was validated using a 3D PSS printing model and a field test. The results indicated that this approach could recognize assembly components with an intersection over union (IoU) of 95% and evaluate assembly performance with an error of less than 5%.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.67-74
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• 2008

Even though the efficiency of a point based black spot improvement project has been low, none of solid methodology, which is based on section not point, and is considered as one of the promising substitute, has not been come up with yet. Thus, this research aims at proposing the adequate length of a hazardous section and a method to set segment length over which the project needs to be performed on rural highways by analyzing the distances from project-conducted sites to new black spots in the following year and distances between project needed but not conducted sites and new black spots in the following year. According to the analysis, the probability of being a new black spot near the project conducted intersection is higher than that of a non-conducted intersection within 2km, however, no strong relationships between project types and distance distribution have been found. Based on those findings, a method to determine the target segment including adjacent black spots within 2 kilometers-range was proposed.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.228-237
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• 2007

displacement mapping enables us to add realistic details to polygonal meshes without changing geometry. We present a real-time artifacts-free inverse displacement mapping method. In each pixel, we construct a ray and trace the ray through the displacement map to find an intersection. To skip empty regions safely, we traverse the image pyramid of displacement map in top-down order. Furthermore, when the displacement map is enlarged, intersection with bilinear interpolated displacement map can be found. When the displacement map is at distance, our method supports mipmap-like prefiltering to enhance image quality and speed. Experimental results show that our method can produce correct images even at grazing view angles. Rendering speed of a test scene is over hundreds of frames per second and the influence of resolution of displacement map to rendering speed is little. Our method is simple enough to be added to existing virtual reality systems easily.

• Journal of Korean Foot and Ankle Society
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• v.21 no.4
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• pp.128-134
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• 2017

Purpose: To introduce reliable and newly developed radiographic measures based on a lateral ankle radiograph to assess a syndesmotic reduction after screw fixation and to compare with the radiographic measures based on the anteroposterior (AP) and mortise radiographs. Materials and Methods: The postoperative ankle radiographs of 34 ankle fracture cases after screw fixation for concurrent syndesmosis injury were reviewed. Two radiographic parameters were measured on each AP and mortise radiograph; tibiofibular clear space (TFCS) and tibiofibular overlap (TFO). Five radiographic parameters were measured on the true lateral radiographs; the anteroposterior tibiofibular (APTF) ratio, anterior tibiofibular ratio (ATFR), posterior tibiofibular ratio (PTFR), distances of intersection of the anterior fibular border and the tibial plafond to anterior cortex of the tibia (AA'), and the intersection of posterior fibular border and tibial plafond to the tip of the posterior malleolus (BB'). In addition, the distance (XP) between the fibular posterior margin (X) crossing tibial plafond or the posterior malleolus and posterior articular margin (P) of the tibial plafond was measured on the lateral view. Results: Using TFCS and TFO in the AP and mortise radiographs, malreductions of syndesmosis were estimated in 17 of 34 cases (50.0%). Using the introduced and developed radiographic measures in the lateral radiographs, syndesmotic malreductions were estimated in 16 out of 34 cases (47.1%). Seventeen cases (50.0%) showed no evidence of postoperative diastasis using the radiographic criteria on the AP and mortise view, 10 cases (58.8%) of whom showed evidence of a malreduction on the lateral radiograph. The newly developed measurements, XP, were measured 0 in 11 out of 34 cases (32.4%). Conclusion: The reduction of syndemosis after screw fixation can be accurately assessed intraoperatively with a combination of several reliable radiographic measurements of the lateral radiograph and traditional radiographic measurements of the AP and mortise radiograph.