• Geomechanics and Engineering
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• 제24권3호
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• pp.227-235
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• 2021

A criterion and a method for solving a problem on the prevention of mine working fracture under the action of tectonic and gravitational forces are offered. Based on minimal criterion, theoretical analysis of the definition of the optimal shape of working in the rock mass weakened by arbitrarily located rectilinear cracks was carried out. A closed system of algebraic equations allowing to minimize the stress state and stress intensity factors depending on mechanical and geometrical characteristics of the rock, is constructed. The relation between the shape of the working and the stress intensity factors and also location and sizes of the cracks is obtained. The found optimal shape of working increases load-bearing capacity of the rock.

• Communications for Statistical Applications and Methods
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• 제30권1호
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• pp.37-48
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• 2023

Shape analysis is a method for measuring, describing and comparing the shape of objects in geometric space. An important aspect is to obtain Procrustes distance based on least square method. We note that the shape is all the geometrical information that remains when location, scale and rotational effects are filtered out from an object. However, and unfortunately, when we cannot measure some landmarks which are some biologically or geometrically meaningful points of any object, it is not possible to measure the variation of all shapes of an object, including that of the incomplete object. Hence, we need to replace the missing landmarks. In particular, Albers and Gower (2010) studied the missing rows of configurations in Procrustes analysis. They noted that the convergence of their approach can be quite slow. In this study, alternatively, we derive an algorithm for estimating the missing landmarks based on the pre-shapes. The pre-shape is invariant under the location and scaling of the original configuration with the centroid size of the pre-shape being one. Therefore we expect that we can reduce the amount of total computing time for obtaining the estimate of the missing landmarks.

• Advances in aircraft and spacecraft science
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• 제4권4호
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• pp.487-501
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• 2017

The main purpose of the paper is to analyze effect of geometrical parameters of the reentry capsules such as radius of the spherical cap, shoulder radius, back shell inclination angle and overall length on the flow field characteristics. The numerical simulation with viscous flow past ARD (Atmospheric Reentry Demonstrator), Soyuz (Russian) and OREX (Orbital Reentry EXperimental) reentry capsules for freestream Mach numbers range of 2.0-5.0 is carried out by solving time-dependent, axisymmetric, compressible laminar Navier-Stokes equations. These reentry capsules appear as bell, head light and saucer in shape. The flow field features around the reentry capsules such as bow shock wave, sonic line, expansion fan and recirculating flow region are well captured by the present numerical simulations. A low pressure is observed immediately downstream of the base region of the capsule which can be attributed to fill-up in the growing space between the shock wave and the reentry module. The back shell angle and the radius of the shoulder over the capsule are having a significant effect on the wall pressure distribution. The effects of geometrical parameters of the reentry capsules will useful input for the calculation of ballistic coefficient of the reentry module.

• 대한전자공학회논문지TE
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• 제37권2호
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• pp.33-40
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• 2000

본 연구에서는 패턴인식과 영상압축을 목적으로 2-D 영상내에 포함되어 있는 물체들의 복잡한 형상을 형태론적 연산을 이용하여 단순한 원시형상 요소들로 분해하는 방법에 관해 연구하였다. 기존의 형태론적 형상분해 알고리즘에서 가장 큰 문제점은 형상을 표현하고 기술하는데 필요한 원시형상 요소의 수가 너무 많이 생성된다는 것이다. 본 논문에서는 이러한 문제점을 개선하기 위하여 형상의 기하학적인 특징과 가장 유사한 원시형상 요소와 4개의 스캔모드를 사용하는 형상 분해법을 새롭게 제안하였다. 제안된 알고리즘은 4개의 스 캔모드를 사용해서 원판, 정사각형, 마름모 꼴 등으로 구성되는 원시형상 요소를 추출하는 방법이다. 이와 같은 알고리즘은 기술 오차를 줄이면서 원시형상 요소의 수를 줄여 기술효율을 높일 수 있는 방법으로 최소의 중복성을 보장할 수 있으며, 알고리즘이 단순하고 계산 시간이 감소한다는 특징이 있다.

• 전자공학회논문지S
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• 제36S권9호
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• pp.67-75
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• 1999

본 논문에서는 패턴인식과 영상압축을 목적으로 2-D 영상내에 포함되어 있는 물체들의 복잡한 형상을 형태론적 연산을 이용하여 단순한 원시형상 요소들로 분해하는 방법에 관해 연구하였다. 기존의 형태론적 형상분해 알고리즘에서 가장 큰 문제점은 형상을 표현하고 기술하는데 필요한 원시형상 요소의 수가 너무 많이 생성된다는 것이다. 본 연구에서는 이러한 문제점을 개선하기 위하여 형상의 기하학적인 특징과 가장 유사한 원시형상 요소와 4개의 스캔모드를 사용하는 형상분해법을 새롭게 제안하였다. 제안된 알고리즘은 4개의 스캔모드를 사용해서 원판, 정사각형, 마름모 꼴 등으로 구성되는 원시형상 요소를 추출하는 방법이다. 이와 같은 알고리즘은 기술 오차를 줄이면서 원시형상 요소의 수를 줄여 기술효율을 높일 수 있는 방법으로 최소의 중복성을 보장할 수 있으며, 알고리즘이 단순하고 계산시간이 감소한다는 특징이 있다.

• 한국지능시스템학회논문지
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• 제20권4호
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• pp.548-553
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• 2010

본 논문에서는 4차원의 히스토그램 기반 상관성을 이용한 효과적인 모양영상의 인식방법을 제안하였다. 여기서 히스토그램 기반 상관성은 4개 방향을 고려한 계산으로 얻어지며, 이는 영상 사이에 대응하는 차원의 위치를 비교함으로써 유사성을 좀 더 정확하게 반영하기 위함이다. 또한 상관성 척도로 정규화된 상호상관계수를 이용함으로써 모양, 위치, 크기, 회전과 같은 기하학적 변화에 강건한 인식성능을 얻기 위함이다. 제안된 방법을 8개의 $64\times64$ 픽셀의 모양영상과 30개의 $256\times256$ 픽셀의 모양영상을 대상으로 실험한 결과, 영상의 속성을 잘 반영하는 우수한 인식성능이 있음을 확인하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.155-159
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• 2007

We conduct intelligent simulation of three-dimensional forging processes in this paper. A new remeshing technique is employed for this purpose. Not only the state variables including strain and strain-rate but also the geometrical features including die-material contact conditions and the characteristic lines or surfaces are taken into account during remeshing. The presented approach is applied to the Baden-Baden benchmark test example and its influence on the simulated results is discussed particularly in terms of the deformed shape with emphasis on the characteristic line.

• Journal of Biosystems Engineering
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• 제21권3호
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• pp.315-324
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• 1996

This study was one of a series of studies on application of machine vision and image processing to extract the geometrical features of plants and to analyze plant growth. Several algorithms were developed to measure morphological properties of plants and describing the growth development of in-situ lettuce(Lactuca sativa L.). Canopy, centroid, leaf density and fractal dimension of plant were measured from a top viewed binary image. It was capable of identifying plants by a thinning top viewed image. Overlapping the thinning side viewed image with a side viewed binary image of plant was very effective to auto-detect meaningful nodes associated with canopy components such as stem, branch, petiole and leaf. And, plant height, stem diameter, number and angle of branches, and internode length and so on were analyzed by using meaningful nodes extracted from overlapped side viewed images. Canopy, leaf density and fractal dimension showed high relation with fresh weight or growth pattern of in-situ lettuces. It was concluded that machine vision system and image processing techniques are very useful in extracting geometrical features and monitoring plant growth, although interactive methods, for some applications, were required.

• Journal of Computational Design and Engineering
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• 제2권1호
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• pp.47-54
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• 2015

In recent years, 3D printers have become popular as a means of outputting geometries designed on CAD or 3D graphics systems. However, the complex user interfaces of standard 3D software can make it difficult for ordinary consumers to design their own objects. Furthermore, models designed on 3D graphics software often have geometrical problems that make them impossible to output on a 3D printer. We propose a novel AR (augmented reality) 3D modeling system with an air-spray like interface. We also propose a new data structure (octet voxel) for representing designed models in such a way that the model is guaranteed to be a complete solid. The target shape is based on a regular polyhedron, and the octet voxel representation is suitable for designing geometrical objects having the same symmetries as the base regular polyhedron. Finally, we conducted a user test and confirmed that users can intuitively design their own ornaments in a short time with a simple user interface.

• 한국공작기계학회논문집
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• 제13권6호
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• pp.17-22
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• 2004

A study for investigating the effects of the cutting conditions (radial depth of cut feed per tooth) and the number of tooth on the side wall of prismatically milled workpiece is described. This study is available not only for understanding the geometrical characteristics of the end milled side wall but also for finding the optimal cutting conditions. In this work, the side wall geometry was characterized by the straightness and the location of maximum peak point. Through this study, it was revealed that the geometrical characteristics of the end milled side wall are strongly related to the material removal per tooth and the number of tooth.