• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.23-35
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• 2012

This paper presents a 3-D pose (position and orientation) estimation method for an elliptic object in 3-D space. It is difficult to resolve the problem of determining 3-D pose parameters with respect to an elliptic feature in 3-D space by interpretation of its projected feature onto an image plane. As an alternative, we propose a two points-based pose estimation algorithm to seek the 3-D information of an elliptic feature. The proposed algorithm determines a homogeneous transformation uniquely for a given correspondence set of an ellipse and two coplanar points that are defined on model and image plane, respectively. For each plane, two triangular features are extracted from an ellipse and two points based on the polarity in 2-D projection space. A planar homography is first estimated by the triangular feature correspondences, then decomposed into 3-D pose parameters. The proposed method is evaluated through a series of experiments for analyzing the errors of 3-D pose estimation and the sensitivity with respect to point locations.

• Communications of Mathematical Education
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• v.24 no.3
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• pp.731-744
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• 2010

Nowadays in school mathematics, the skill and method for solving problems are often emphasized in preference to the theoretical principles of mathematics. Students pay attention to how to make an equation mechanically before even understanding the meaning of the given problem. Furthermore they do not get to really know about the principle or theorem that were used to solve the problem, or the meaning of the answer that they have obtained. In contemporary textbooks the conic section such as circle, ellipse, parabola and hyperbola are introduced as the cross section of a cone. But they do not mention how conic section are connected with the quadratic equation or how these curves are related mutually. Students learn the quadratic equations of the conic sections introduced geometrically and are used to manipulating it algebraically through finding a focal point, vertex, and directrix of the cross section of a cone. But they are not familiar with relating these equations with the cross section of a cone. In this paper, we try to understand the quadratic curves better through the analysis of the discussion made in the process of the discovery and eventual development of the conic section and then seek for way to improve the teaching and learning methods of quadratic curves.

• Journal of Veterinary Clinics
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• v.36 no.6
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• pp.297-300
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• 2019

Wii^® balance board (WBB) is a device that can measure and record body sway. This study was conducted to evaluate the reliability of WBB in small sized dog as inexpensive, portable and convenient tool. The center of pressure path length (CPPL) and 95% confidence ellipse area (Area 95) were evaluated with only two plates of WBB. The parameters were evaluated between no load (0 kg) and mass group (0.25-4 kg on each one plate). 23 dogs (2.3-7.3 kg) were evaluated for with hindlimb standing for 10 seconds. The mass group showed a significant value in comparison to the no load during the measurement. And intra-class correlation coefficients (ICCs) between CPPL and Area 95 revealed very high both mass and dog group. In the evaluation of medial patellar luxation (MPL) as a diagnostic tool, 80 dogs with MPL and 23 non-affected dogs were used. In studies of CPPL and Area 95, significant differences were found between non-affected and MPL groups for 10 and 30 seconds, respectively. The WBB can be used as a valid tool for evaluating hind limb standing balance and can be useful as an objective tool to present clinical results in small sized dog with MPL.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.32.1-32.1
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• 2016

Early-type galaxies (ETGs) are supposed to follow the virial relation M ~ sigma^2 * R_e, with M being the galaxy mass, sigma being the stellar velocity dispersion, and R_e being the (2D) effective radius. I apply this relation to (a) the ATLAS3D sample and (b) the sample of Saglia et al. (2016). The two datasets reveal a statistically significant tilt of the empirical relation relative to the theoretical virial relation such that M ~ (sigma^2 * R_e)^0.92 with zero intrinsic scatter. This tilt disappears when replacing R_e with the semi-major axis of the projected half-light ellipse, a. Accordingly, a, not R_e, is the correct proxy for the scale radius of ETGs. By geometry, this implies that early-type galaxies are axisymmetric and oblate in general, in agreement with recent results from modeling based on kinematics and light distributions.

• Korean Journal of Hazardous Materials
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• v.6 no.2
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• pp.62-67
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• 2018

It is very important to classify explosion hazardous area in order to prevent an accident explosion. In order to prevent such a explosion, the Industrial Safety and Health Standards Rules stipulates the establishment and management of explosion hazards in accordance with the criteria set by the Korean Industrial Standards. This study has investigated the range of the explosion hazardous area according to various hole sizes, pressures, vapor densities, and wind velocities in the outdoor flammable liquid tank using KS C IEC-60079-10-1 $2^{nd}$ Ed.(=IEC CODE) and PHAST. The results show that the explosion hazardous areas by IEC CODE have circle shapes. However, the areas by PHAST show ellipse shapes. The different of the explosion hazardous areas increases with the increase of wind velocity.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.1-6
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• 2007

This study investigated the magnetic properties of $Ni_{80}Fe_{20}/SiO_2$ laminates with shape-induced magnetic anisotropy. The multilayer films were deposited on Si or upilex substrates, from separate $Ni_{80}Fe_{20}$ and $SiO_2$ (at %) alloy targets using a rf diode sputtering system. $Ni_{80}Fe_{20}/SiO_2$ laminates with a various number of bilayers (N) were prepared. The laminates with ellipse array patterns were prepared using photolithographic technique. The magnetic properties were measured at room temperature using a B-H hysteresisgraph and a high frequency permeameter. The several steps during domain wall reversal were observed in multilayer films, attributing to inter-magnetic layer coupling. Intrinsic uniaxial anisotropy field increases with N. The experimental values of the total anisotropy field are found to be in good agreement with the calculated values. This study utilized the shape anisotropy of the laminated film objects with small ellipse array patterns to induce a larger uniaxial anisotropy so as to maximize their operating frequency.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.2
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• pp.37-48
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• 2006

HF radar-derived current data obtained in 2002 and 2004 are analyzed to examine the effects of the completion of the Saemangeum 4th tidal dyke in June 2003, connecting Gogunsan-Gundo and Bieung-Do, on the coastal surface $M_2$ current pattern. Comparison between the currents by HF radar and current meter mooring showed good agreements. Counterclockwise rotation of the $M_2$ current in the observed area did not change with the dyke construction. Strong westward ebb jet from the gap of the dyke was observed in 2002 but disappeared in 2004. The complete closing of the dyke gap caused the current speed increase around the mouth of the Kem River estuary, decrease around Gogunsan-Gundo and the dyke, the changes in the direction of maximum current to north-ward from eastward and the delay of the maximum flood current occurrence around Gogunsan-Gundo and the dyke. Around Yeon-Do, the maximum flood current directed more clockwise and occurred rather earlier. These changes of the $M_2$ current ellipse characteristics imply that the effects of the dyke construction reached the area connecting Mal-Do and Yeun-Do.

• Journal of Biosystems Engineering
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• v.19 no.1
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• pp.9-16
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• 1994

135 and 136 pine cones were sampled from age class of II to VI Korean pine trees for the study of their physical properties in 1991 and 1992, respectively. The length, width, weight, volume, and the largest projected area of cones were measured, and the specific gravity, apparent volume ratio sphericity, and roundness were calculated. Regression analysis were performed for the weight, volume, and projected area to the cone length and width. The length, and major and minor diameters of the cone stalks were measured and analyzed. 1. The range of the length of cone stalks was 0 to 47.3mm. The average length of stalks were 9mm ('91) and 10mm('92), respectively. Cross section of the stalks was ellipse with average major and minor diameters of 9.1mm and 10.1mm, and 8.6 and 8.7mm in 91 and 92, respectively. 2. The length of pine cones distributed from 8cm to 17cm and the average length were about 13cm('91, '92). The width varied from 5cm to 9.5cm and the average width were 6.7cm('91) and 6.9cm('92). The ratios of the length to the width were 0.56('91) and 0.65('91) and the shape of the cones were found to be ellipse with minor diameter of 1/2 to 2/3 of the major diameter. 3. The roundnesses and sphericity of cones were 0.74 and 0.75('91), 0.63 and 0.67('92), respectively. The average of the largest projected area of cones were $85.3cm^2$('91) and $93.1cm^2$('92) and the criterion areas were $71.0cm^2$ and $74.5cm^2$, respectively. 4. Cone weights were from 83g to 467g('91 and '92) and averages were 186g('91) and 220g('92). The average specific gravities were 0.89 and 0.96('91 and '92). The true volumes were $212cm^2$('91) and $230cm^2$('92), and the average bulk volume was $321cm^2$('91, '92). The average apparent volume ratios of cones were 35% ('91) and 28% ('92), respectively. 5. The weight and the volume were proportional to the length of the cone multiplied by the width squred and the largest projected area was proportional to the length multiplied by the width of cones.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.444-450
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• 1998

In the present investigation, it is attempted to derive a yield function and associated flow rules of loose metal powders to predict plastic deformation and density change during compaction. The loose metal powders yield by shear stress as well as hydrostatic stress and the yield strength is much smaller in tension than compression. Therefore, a yield function for the powders is expressed as a shifted ellipse toward the negative direction in the hydrostatic stress axis in the space defined by the two stresses. Each of parameters A, B and .delta. used in the yield function is expressed as a function of relative density and it is determined by uniaxial strain and hydrostatic compressions using Cu powder. Flow rules obtained by imposing the normality rule to the yield function are applied to the analyses of unidirectional, bidirectional and hydrostatic compressions, resulting in an excellent agreement with experiments. The yield function is further examined by checking volume changes in plane stain, uniaxial strain and shear deformations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.408-415
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• 1998

The analysis model is the power law creep material containing an elliptical rigid inclusion subjected to the arbitrarily directional stress on infinite boudary. The stress analysis is performed using the conformal mapping function and complex pseudo-stress function. The stress distributions near an elliptical rigid inclusion are obtained with various ellipse shapes, strain hardening exponents and directions of applied stress.