• International Journal of CAD/CAM
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• v.6 no.1
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• pp.105-115
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• 2006

Thickness is a commonly used parameter in product design and manufacture. Its intuitive definition as the smallest dimension of a cross-section or the minimum distance between two opposite surfaces is ambiguous for intricate solids, and there is very little reported work in automatic computation of thickness. We present three generic definitions of thickness: interior thickness of points inside an object, exterior thickness for points on the object surface, and radiographic thickness along a view direction. Methods for computing and displaying the respective thickness values are also presented. The internal thickness distribution is obtained by peeling or successive skin removal, eventually revealing the object skeleton (similar to medial axis transformation). Another method involves radiographic scanning along a viewing direction, with minimum, maximum and total thickness options, displayed on the surface of the object. The algorithms have been implemented using an efficient voxel based representation that can handle up to one billion voxels (1000 per axis), coupled with a near-real time display scheme that uses a look-up table based on voxel neighborhood configurations. Three different types of intricate objects: industrial (press cylinder casting), sculpture (Ganesha idol), and medical (pelvic bone) were used for successfully testing the algorithms. The results are found to be useful for early evaluation of manufacturability and other lifecycle considerations.

• Journal of the Korean Society of Visualization
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• v.7 no.2
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• pp.42-46
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• 2010

In this paper we report the method of visualizing and measuring the fluid flow within a small droplet of millimeter size. We use a vertical laser sheet in visualization of the micrometer size and special attention is given to the arrangement of microscope to obtain clear images. Then we use a PIV technique to measure the velocity of the internal flow from the images taken. Since the droplet is of spherical shape, the images represent highly deteriorated picture of the real objects due to the refraction phenomenon. In order to compensate the refraction, we in this study developed two kinds of methods for the real velocity. In the first method, the refracted images are directly used to obtain the velocity in the image space, and then the velocity is transformed to the real space. In the second method the images are first transformed to the real-space objects, and then the PIV is used to measure the velocity field. We compared the two results to prove the usefulness of the compensation technique.

• Journal of KIISE:Software and Applications
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• v.29 no.5
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• pp.336-344
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• 2002

In concurrent object-oriented languages, inheritance and concurrence are the primary features. But concurrent objects and inheritance have conflicting characteristics thereby simultaneously use of them causes the problem, so called inheritance anomaly, which requires code redefinition of inherited methods to maintain integrity of objects. In this paper, to solve this inheritance anomaly without broken of encapsulation, we introduce the state abstraction concept and map internal states of the encapsulated object into abstract slates. And also, we design the inheritance interface for efficient inheritance. Through the inheritance interface containing abstract state set, though redefinition of the method is incurred, we can remove the influence of other classes in inheritance hierarchy. And also, we can solve the inheritance anomaly problems.

• The Journal of Internal Korean Medicine
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• v.28 no.4
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• pp.863-871
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• 2007

Objects : To gain better insights of East-west integrated treatment of ischemic stroke. We analyzed 89 patients with severe acute ischemic stroke who were admitted to the East-west integrated intensive care unit. Methods : Subjects enrollment was from the East-west integrated intensive care unit of Kyung Hee Medical Center from March 2006 to February 2007. Patients were admitted within 14 days after the onset of ischemic stroke. We assessed the subjects' general characteristics, risk factors, admitting routes and periods, diagnostic imaging, process of western treatment and Korean traditional treatment, complication and consequence. Results : The proportion of males was 50.6%, of females 49.4%, average age was male 66.0$\pm$10.3 and female 71.1$\pm$10.5. Average length of hospital stays was 19.5 days. Monthly admissions were highest in November and December. The admission route was through emergency room (61.8%) or ward (34.8%). Mean Glasgow coma scale score was 10.0$\pm$2.5, average time from symptom of onset to hospital admission was 2.3$\pm$2.2 days. Dominant ischemic vascular territory was middle cerebral artery (66.3%). Initial western treatment was argatroban (22.5%), urokinase (28.1%), and heparinization (38.2%). Distribution of Sasang constitution of So-yang to Tae-eum to So-eum was equal to 5.4 to 2.9 to 1.5. Major complications were observed in 40 (42.7%) patients. In hospital mortality was 12.4% (11 deaths), all of them caused by aggravation of neurological deficit and only 3 of them with major complications. There appears to be a significant positive relationship between length of hospital stay and occurrence of complications (P<0.05). After discharge from the ICU, 64 (71.9%) patients were improved, 11 (12.4%) patients had expired, and 14 (15.8%) patients were transferred. Conclusions : From this study, we suggest that patients with severe acute ischemic stroke should be treated with East-west integrated therapy for more favorable consequences and decreased mortality.

• Journal of Digital Convergence
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• v.10 no.3
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• pp.167-172
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• 2012

This paper presents the technique separating objects on the single frame image from the background using region segmentation technique based on active contour. Active contour is to extract contours of objects from the image, which is set to have multi-search starting point to extract each objects contours for multi-object segmentation. Initial rough object segments are generated from binary-coded image using object specific contour information, and then the hole filling is performed to compensate internal segmentation caused by the change of inner object hole area and pixels. This procedure complements the problems caused by the noise from the region segmentation and the errors of segmentation near by the contour. The proposed method and conventional method is compared to verify the superiority of the proposed method.

• Journal of Korea Multimedia Society
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• v.9 no.4
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• pp.421-433
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• 2006

This paper proposes a method to insert virtual objects into a real video stream based on feature tracking and camera pose estimation from a set of single-camera video frames. To insert or modify 3D shapes to target video frames, the transformation from the 3D objects to the projection of the objects onto the video frames should be revealed. It is shown that, without a camera calibration process, the 3D reconstruction is possible using multiple images from a single camera under the fixed internal camera parameters. The proposed approach is based on the simplification of the camera matrix of intrinsic parameters and the use of projective geometry. The method is particularly useful for augmented reality applications to insert or modify models to a real video stream. The proposed method is based on a linear parameter estimation approach for the auto-calibration step and it enhances the stability and reduces the execution time. Several experimental results are presented on real-world video streams, demonstrating the usefulness of our method for the augmented reality applications.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.21-27
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• 2002

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. A number of visual or optical technologies have been successfully applied to measure three-dimensional surfaces. However, those conventional visual or optical methods have inherent shortcomings such as occlusion and variant surface reflection. X-ray vision system can be a good solution to these conventional problems, since we can extract the volume information including both the surface geometry and the inner structure of any objects. In the x-ray system, the surface condition of an object, whether it is lambertian or specular, does not affect the inherent characteristics of its x-ray images. In this paper, we propose a three-dimensional x-ray imaging method to reconstruct a three dimensional structure of an object out of two dimensional x-ray image sets. To achieve this by the proposed method, two or more x-ray images projected from different views are needed. Once these images are acquired, the simultaneous algebraic reconstruction technique(SART) is usually utilized. Since the existing SART algorithms have several shortcomings such as low performance in convergence and different convergence within the reconstruction volume of interest, an advanced SART algorithm named as USART(uniform SART) is proposed to avoid such shortcomings and improve the reconstruction performance. Because, each voxel within the volume is equally weighted to update instantaneous value of its internal density, it can achieve uniform convergence property of the reconstructed volume. The algorithm is simulated on various shapes of objects such as a pyramid, a hemisphere and a BGA model. Based on simulation results the performance of the proposed method is compared with that of the conventional SART method.

• Journal of KIISE:Databases
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• v.31 no.6
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• pp.624-640
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• 2004

Recently, with the rapid development of location-based techniques, index structures to efficiently manage moving objects have been required. In this paper, we propose a new spatio-temporal index structure that supports a future position retrieval and minimizes a update cost. The proposed index structure combines an assistant index structure that directly accesses current positions of moving objects with KDB-tree that is a space partitioning access method. The internal node in our proposed index structure keeps time parameters in order to support the future position retrieval and to minimize a update cost. Moreover, we propose new update and split methods to maximize the space utilization and the search performance. We perform various experiments to show that our proposed index structure outperforms the existing index structure.

• The Journal of Advanced Prosthodontics
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• v.16 no.2
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• pp.91-104
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• 2024

PURPOSE. The objectives of the current study were to estimate the influence of self-reinforced hollow structures with a graded density on the dimensional accuracy, weight, and mechanical properties of Co-Cr objects printed with the direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS. Sixty-five dog-bone samples were manufactured to evaluate the dimensional accuracy of printing, weight, and tensile properties of DMLS printed Co-Cr. They were divided into Group 1 (control) (n = 5), Group 2, 3, and 4 with incorporated hollow structures based on (spherical, elliptical, and diamond) shapes; they were subdivided into subgroups (n = 5) according to the volumetric reduction (10%, 15%, 20% and 25%). Radiographic imaging and microscopic analysis of the fractographs were conducted to validate the created geometries; the dimensional accuracy, weight, yield tensile strength, and modulus of elasticity were calculated. The data were estimated by one-way ANOVA and Duncan's tests at P < .05. RESULTS. The accuracy test showed an insignificant difference in the x, y, z directions in all printed groups. The weight was significantly reduced proportionally to the reduced volume fraction. The yield strength and elastic modulus of the control group and Group 2 at 10% volume reduction were comparable and significantly higher than the other subgroups. CONCLUSION. The printing accuracy was not affected by the presence or type of the hollow geometry. The weight of Group 2 at 10% reduction was significantly lower than that of the control group. The yield strength and elastic modulus of the Group 2 at a 10% reduction showed means equivalent to the compact objects and were significantly higher than other subgroups.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 1996.06a
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• pp.79-109
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• 1996

In order to transform the underground utility data into the 3-D spatial objects, this thesis defined the type of the 3-D spatial objects and the storage structure of objects, and developed the spatial data transformation system that transforms the 2-D underground utility data into the pre-defined 3-D spatial objects through the Booch Method, an object-oriented development method. For this sake, the relational data model of ARC/INFO and the storage structure are analyzed, as well as the pre-requisites, required for the 3-D visualization of the underground utilities. Also, the 2-D underground utility data, saved in ARC/INFO, were transformed into the ASCII files through the internal pre-processing procedure, then used as the input data of the transformation system. In addition, to develop the transformation system, the object-oriented development methods are studied first and, then, applied to the system analysis and the design procedure with the Booch Method as a development method. Finally, the results of analysis and design procesure are implemented through AML, a ARC/INFO macro language, and C++, an object-oriented programing language. As a result of this study, the 3-D spatial objects that can visualize the 2-D utilities in 3-D, are acquired, and the adaptation of object-oriented development method to the system development procedure enabled an effective development prodedure.