• Structural Engineering and Mechanics
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• v.10 no.2
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• pp.93-110
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• 2000

An alternative interpretation of the completeness requirements for the higher order elements is presented. Apart from the familiar condition, $\sum_iN_i=1$, some additional conditions to be satisfied by the shape functions of higher order elements are identified. Elements with their geometry in the natural form, i.e., without any geometrical distortion, satisfy most of these additional conditions inherently. However, the geometrically distorted elements satisfy only fewer conditions. The practical implications of the satisfaction or non-satisfaction of these additional conditions are investigated with respect to a 3-node bar element, and 8- and 9-node quadrilateral elements. The results suggest that non-satisfaction of these additional conditions results in poorer performance of the element when the element is geometrically distorted. Based on the new interpretation of completeness requirements, a 3-node element and an 8-node rectangular element that are insensitive to mid-node distortion under a quadratic displacement field have been developed.

• Journal of Digital Contents Society
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• v.3 no.2
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• pp.197-209
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• 2002

If we reduce the number of vertexes to decrease bit rate in polygon-based shape coding, the distortion of approximated contour increases rapidly. On the other hand, if we reduce the distortion, the number of vertexes increases rapidly and many bits are required to encode the vertexes. To improve this problem, in this paper we propose the approximation vertex search method. The encoder in the proposed method searches the type of distortion patterns that is the most similar to the shape which polygon edge and contour segment form and then encodes it. And then, the decoder mathematically finds the approximated vertexes from decoded distortion pattern information. Therefore, the proposed algorithm results in encoding many vertexes at a low bit rate and having the smoother shape than conventional method. As shown in computer simulation, the proposed method has less distortion than conventional method. It costs less bit rate by $10{\sim}20%$ than conventional algorithm in same distortion.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.153-160
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• 2019

Welding often results in welding distortion during the assembly process. The welding distortion of thin-plate structures such as the living quarters of ships and offshore installations is a more significant problem than in the case of thick-plate structures. Pre-stressing/heating and fairing, which are additional works to mitigate and control welding distortion, are inevitable, and the construction planning is accordingly delayed. In order to prevent welding distortion and minimize the additional work during the assembly process, increasing the plate thickness and/or the number of stiffeners may be a simple solution, but it may give rise to problems related to cost and weight. In this study, the welding distortion control effect of the type of stiffeners on the door openings of various living quarter structures was investigated using an experimental method and a finite element method. The results showed the feasibility of mitigating and controlling the welding distortion, and the optimum selection of the type of stiffeners was confirmed.

• Korean Journal of Computational Design and Engineering
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• v.13 no.1
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• pp.1-7
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• 2008

Data compression becomes increasingly an important issue for reducing data storage spaces as well as transmis-sion time in network environments. In 3D geometric models, the normal vectors of faces or meshes take a major portion of the data so that the compression of the vectors, which involves the trade off between the distortion of the images and compression ratios, plays a key role in reducing the size of the models. So, raising the compression ratio when the normal vector is compressed and minimizing the visual distortion of shape model's shading after compression are important. According to the recent papers, normal vector compression is useful to heighten com-pression ratio and to improve memory efficiency. But, the study about distortion of shading when the normal vector is compressed is rare relatively. In this paper, new normal vector compression method which is clustering normal vectors and assigning Representative Normal Vector (RNV) to each cluster and using the angular deviation from actual normal vector is proposed. And, using this new method, Visually Undistinguishable Lossy Compression (VULC) algorithm which distortion of shape model's shading by angular deviation of normal vector cannot be identified visually has been developed. And, being applied to the complicated shape models, this algorithm gave a good effectiveness.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.2
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• pp.59-70
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• 1996

Given the flow matrix, plant size (rectangle shape) and department sizes, the algorithm in this paper provides the plant layout with rectilinear distance measure. To construct automated facility design, eigenvector approach is employed. A branch and bound computer code developed by Tillinghast is modified to find the feasible fits of departments without shape distortion (see [1])in the plant rectangle. The computational results compared with CRAFT are shown.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.903-909
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• 2012

In elliptical vibration cutting(EVC) where the cutting tool traces a micro-scale 2-dimensional elliptical trajectory, the kinematical and vibrational characteristics of the EVC device greatly affect cutting performance. In this study, kinematical and vibrational characteristics of an EVC device constructed with two orthogonally-arranged stacked piezoelectric actuators were investigated both analytically and experimentally. The step voltage was applied to the orthogonal EVC device and the associated displacements of the cutting tool were measured to assess kinematical characteristics of the orthogonal EVC device. To investigate the vibrational characteristic of the orthogonal EVC, sinusoidal voltage was applied to the EVC device and the resulting displacements were measured. It was found from experiments that coupling of displacements in the thrust and cutting directions and the tilt of the major axis of the elliptical trajectory exists. In addition, as the excitation frequency is in vicinity of resonant frequencies the distortion in the shape of the elliptical trajectory becomes greater and change in the rotation direction occurs. To correct the shape distortion of the elliptical trajectory, the shape correcting procedure developed for the parallel EVC device was applied for the orthogonal EVC device and it was shown that the shape correcting method successfully corrects distortion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.46-50
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• 2012

Stainless steel and titanium used for orthopedic prosthetic metal, magnetic resonance imaging was measured quantitatively the extent of distortion. Based on reading tests at varying metal magnetic resonance imaging (MRI) were investigated. To two image acquisition conditions for having three metal bodies mutually quantitative it compared analyzed the image of cross direction and the image of lengthwise. As for the distortion of the magnetic resonance image, as for the distortion of image it became small in the order of Clip, Strainless and Titanium. In addition, with T1WI and T2WI which are image acquisition condition T2WI the distortion of image became small. As for the distortion of the image by the metal, you could see the distortion of image in elliptical shape, the metal a bigger image distortion appeared in many parts. If clinical doctor has the condition of the same operation, use the Titanium material, it can, raising the diagnostic value of magnetic resonance image inspection after the operating from Stainless.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.97-100
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• 2000

This paper presents a new approach to the vertex based shape coding technique. The conventional approaches encode objects using a spline method with the same distortion coefficients. The proposed approach, however, classifies the objects based on the object's features, and then applies different distortion values depending on the classified object types. Using this pre-classifying technique, this paper reduces the bit rate and the computational complexity necessary for the encoding process. The performance of the proposed method has been proved by experiments on the various sample Images.

• Structural Engineering and Mechanics
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• v.38 no.3
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• pp.261-281
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• 2011

A new method of formulation of a class of elements that are immune to mesh distortion effects is proposed here. The simple three-noded bar element with an offset of the internal node from the element center is employed here to demonstrate the method and the principles on which it is founded upon. Using the function space approach, the modified formulation is shown here to be superior to the conventional isoparametric version of the element since it satisfies the completeness requirement as the metric formulation, and yet it is in agreement with the best-fit paradigm in both the metric and the parametric domains. Furthermore, the element error is limited to only those that are permissible by the classical projection theorem of strains and stresses. Unlike its conventional counterpart, the modified element is thus not prone to any errors from mesh distortion. The element formulation is symmetric and thus satisfies the requirement of the conservative nature of problems associated with all self-adjoint differential operators. The present paper indicates that a proper mapping set for distortion immune elements constitutes geometric and displacement interpolations through parametric and metric shape functions respectively, with the metric components in the displacement/strain replaced by the equivalent geometric interpolation in parametric co-ordinates.

• Journal of Integrative Natural Science
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• v.12 no.2
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• pp.35-43
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• 2019

In the content-based image search properties, form information is simple because only the contours of objects are available, and although it can effectively extract the characteristics of the objects, it is sensitive to external noise. The radial distortion, one of these noises, is most prominent in the eyewear and, due to the structural characteristics of the imaging equipment, radiative distortion occurs in almost all imaging equipment. It is very important to determine the similarity of the objects in the images in which these distortions occurred to the actual objects. In order to improve this problem, we propose a strong image search technique for formative noise and radiative distortion using regularization phase angles and moments. Through simulation using Wang DB, the proposed algorithm proved excellent performance for radiation distortion that occurs in general. In addition, a system optimized for database can be implemented by making appropriate changes to the threshold values, enabling image retrieval with the desired level of confidence in various systems. The algorithm proposed in this paper is expected to be utilized as an optimal imaging system by extracting morphological form information of multimedia data.