• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6C
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• pp.572-578
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• 2007

To establish eye contact in video teleconferencing, it is necessary to synthesize a front view image by viewpoint interpolation. We can find the viewing direction of a user, and interpolate an image seen from that viewpoint, which will result in a face image observed from the front. There are two categories of previous research: image based method and model based method. The former is simple to calculate, however, it shows limited performance for complex objects. And the latter is robust to noise while it is computationally expensive. We propose to approximate face images as ellipses and match them to build an ellipsoid and then synthesize a new image from a given virtual camera position. We show that it is simple and robust from various experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.305-308
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• 2003

This paper proposed Ellipsoid Fuzzy-ART (Fuzzy-Adaptive Resonance Theory) for recognition performance improvement to use Mahalanobis distance. The suggested method uses Mahalanobis distance to decide pattern boundary region at vector space. In order to confirm the validity of proposed method, comparison of the performance has made between existing method and the proposed method through simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.89-90
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• 2011

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1054-1064
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• 2002

Numerical prediction of welding-induced residual stresses using the finite element method has been a common practice in the development or refinement of welded product designs. Various researchers have studied several thermal models associated with the welding process. Among these thermal models, ramp heat input and double-ellipsoid moving source have been investigated. These heat-source models predict the temperature fields and history with or without accuracy. However, these models can predict the thermal characteristics of the welding process that influence the formation of the inherent plastic strains, which ultimately determines the final state of residual stresses in the weldment. The magnitude and distribution of residual stresses are compared. Although the two models predict similar magnitude of the longitudinal stress, the double-ellipsoid moving source model predicts wider tensile stress zones than the other one. And, both the ramp heating and moving source models predict the stress results in reasonable agreement with the experimental data.

• Progress in Medical Physics
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• v.19 no.4
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• pp.227-230
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• 2008

The purpose of this study was to design and construct an ultrasound phantom for volume calibration and evaluate the volume measurement accuracy of a 2 dimensional ultrasonic system. Ultrasound phantom was designed, constructed and tested. The phantom consisted of a background material and a target. The background was made by mixing agarose gel with water. A target, made with an elastic material, was filled with water to vary its volume and shape and inserted into background material. To evaluate accuracy of a 2 dimensional ultrasonic system (128XP, ACUSON), three different shapes of targets (a sphere, 2 ellipsoids and a triangular prism) were constructed. In case of ellipsoid shape, two targets, one with same size length and width (ellipsoid 1) and another with the length 2 times longer than width (ellipsoid 2) were examined. The target volumes of each shape were varied from 94cc to 450cc and measurement accuracy was examined. The volume difference between the real and measured target of the sphere shape ranged between 6.7 and 11%. For the ellipsoid targets, the differences ranged from 9.2 to 10.5% with ellipsoid 1 and 25.7% with ellipsoid 2. The volume difference of the triangular prism target ranged between 20.8 and 35%. An easy and simple method of constructing an ultrasound phantom was introduced and it was possible to check the volume measurement accuracy of an ultrasound system.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.1 s.39
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• pp.47-53
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• 2007

Astronomic surveying has been regarded as an important method for absolute positioning of geodetic datum in each countries under the local geodetic reference system. The purposes of this study are to determine astrogeodetic geoidal heights referred to Bessel ellipsoid and to determine deflection of the vertical and geoidal heights referred to GRS80 of World Geodetic System by astronomic surveying data which have been surveyed after 1970 in Korea. The results show that $\xi$ component of the deflection of the vertical distribute from -5.725" to 8.005" and $\eta$ component distribute from -14.917" to 6.2" and astrogeodrtic geoidal heights distribute from 23 m to 27 m in the study area. Also, we could see that GRS80 was more optimal ellipsoid than Bessel 1841 ellipsoid to Korea through comparing both astrogeotic geoidal heights referred to GRS80 and Bessel 1841 ellipsoid.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.45
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• pp.93-100
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• 1998

The researches of Linear Programming are Khachiyan Method, which uses Ellipsoid Method, and Karmarkar, Affine, Path-Following and Interior Point Method which have Polynomial-Time complexity. In this study, Karmarkar Method is more quickly solved as 50 times then Simplex Method for optimal solution. but some special problem is not solved by Karmarkar Method. As a result, the algorithm by APL Language is proved time efficiency and optimal solution in the Primal-Dual interior point algorithm. Furthermore Karmarkar Method and Primal-Dual interior point Method is compared in some examples.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.1
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• pp.13-23
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• 2020

In this paper, we propose a quantization parameter determination method for face depth image encoding in order to minimize an impact on a face recognition accuracy. When a face depth image is compressed through quantization in H.264/AVC, differential quantization parameters are assigned according to an accuracy of ellipsoid modeling prediction and an importance degree of a unit block in extracting facial features. The simulation results show that the face recognition success rates are improved by up to 6% at the same compression rates through the proposed compression rate determination method.

• Tunnel and Underground Space
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• v.30 no.6
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• pp.551-558
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• 2020

This note presents the calculation of nominal area for rock core specimen under direct shear testing condition. The initial nominal area was assumed as ellipsoid, and the equations for calculating the nominal area are derived. The normalized shear displacement and normalized nominal area have an identical relationship regardless of the ellipsoid shape. New testing constants and the generalized method were suggested to calculate the decrease of the nominal area. The method was applied to calculate the direct shear testing data and the changes of result were discussed.

• Interaction and multiscale mechanics
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• v.1 no.1
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• pp.103-121
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• 2008

This paper presents an optimization-based method for computing a minimal bounding ellipsoid that contains the set of static responses of an uncertain braced frame. Based on a non-stochastic modeling of uncertainty, we assume that the parameters both of brace stiffnesses and external forces are uncertain but bounded. A brace member represents the sum of the stiffness of the actual brace and the contributions of some non-structural elements, and hence we assume that the axial stiffness of each brace is uncertain. By using the $\mathcal{S}$-lemma, we formulate a semidefinite programming (SDP) problem which provides an outer approximation of the minimal bounding ellipsoid. The minimum bounding ellipsoids are computed for a braced frame under several uncertain circumstances.