• Journal of Information Processing Systems
• /
• 제4권4호
• /
• pp.153-158
• /
• 2008

This paper deals with the geometric fitting algorithms for parametric curves and surfaces in 2-D/3-D space, which estimate the curve/surface parameters by minimizing the square sum of the shortest distances between the curve/surface and the given points. We identify three algorithmic approaches for solving the nonlinear problem of geometric fitting. As their general implementation we describe a new algorithm for geometric fitting of parametric curves and surfaces. The curve/surface parameters are estimated in terms of form, position, and rotation parameters. We test and evaluate the performances of the algorithms with fitting examples.

• 대한조선학회논문집
• /
• 제46권1호
• /
• pp.87-95
• /
• 2009

The applicability of optimization techniques for hull surface fitting has been important in the ship design process. In this research, the Genetic Algorithm has been used as a searching technique for solving surface fitting problem and minimizing errors between B-spline surface and the ship's offset data. The encoded design variables are the location of the vertex points and parametric values. The sufficient accuracy in surface fitting implies not only various techniques for computer-aided design, but also the future production design.

• 한국멀티미디어학회논문지
• /
• 제12권1호
• /
• pp.50-57
• /
• 2009

본 논문은 3차원 다각형 모델에서 특징 선을 추출하기 위한 방법에 대해 제안한다. 이산 곡면으로 이루어진 다각형 모델에서 특징 선을 추출하기 위하여 기존 방법에서는 전역적인 음함수 곡면 맞춤 기법(Implicit Surface Fitting)을 이용하여 모델의 꼭지점에서 곡률과 곡률 미분 값을 측정하였다. 이러한 방법은 다각형 모델의 꼭지점에서 음함수 곡면으로 정확하게 투영할 수 있도록 사용자의 정의 파라미타를 찾아야 하며, 특징 추출을 위한 많은 계산 시간을 요구한다. 그러나 제안 방법은 지역적 음함수 곡면 맞춤 기법을 이용하여 모델의 꼭지점에 근사된 곡면을 통해 미분 정보를 측정한다. 측정된 미분 정보를 통해 쉽게 각각의 모서리에서 제로-클로싱을 통해 특징 점을 추출하고, 곡률 방향을 따라 추출된 점들을 연결하여 특징 선을 생성한다. 여러 가지 다각형 모델에서 실험을 하였고 기존 방법보다 빠르며 높은 품질의 특징 선을 추출한다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제53권9호
• /
• pp.532-537
• /
• 2004

Shrink fitting is often a conventional mechanical fasteners and fastening methods with temperature difference. Localized heating of the material surface provides temporary expansion and allows slip fit assembly. The resulting interference fit exhibits exceptional strength without surface deformation at ambient temperatures. We studied an analysing method to find out a deformation of motor axis as variation of constrained method with shrink fitting.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1997년도 추계학술대회 논문집
• /
• pp.230-234
• /
• 1997

Reverse engineering involves digitizing a three-dimensional model or part converting the data to a CAD database description and manufacturing by CNC. Currently, the digitization is done through measurements taken manually by a CMM or touch probe mounted on a CNC machinetool. Some reverse engineering techniques require close integration between the data collection method and the surface-fitting algorithms. Accurate surface data are collected by input to the surface fitting method. This study has been found that both the smoothness of surfaces and accuracy of surface fitting are related with the degree of the interpolated surfaces.

• 한국CDE학회논문집
• /
• 제4권1호
• /
• pp.32-42
• /
• 1999

Approximate lofting or skinning is one of practical surface modeling techniques well used in CAD and reverse engineering applications. Presented in this paper is a method for approximately lofting a given set of curves wihin a specified tolereance. It is based on refitting input curves simultaneously on a common knot vector and interpolating them to get a resultant NURBS surface. A concept of reducing the number of interior knots of the common knot vector is well adopted to acquire more compact representation for the resultant surface. Energy minimization is newly introduced in curve refitting process to stabilize the solution of the fitting problem and get more fair curve. The proposed approximate lofting provides more smooth surface models and realizes more efficient data reduction expecially when the parameterization and compatibility of input curves are not good enough. The method has been successfully implemented in a new CAD/CAM product VX Vision? of Varimetrix Corporation.

• 한국CDE학회논문집
• /
• 제14권1호
• /
• pp.10-17
• /
• 2009

Surface detection and parameter estimation in point cloud is a relevant subject in CAD/CAM, reverse engineering, computer vision, coordinate metrology and digital factory. In this paper we present a software for a fully automatic surface detection and parameter estimation in unordered, incomplete and error-contaminated point cloud with a large number of data points. The software consists of three algorithmic modules each for object identification, point segmentation, and model fitting, which work interactively. Our newly developed algorithms for orthogonal distance fitting(ODF) play a fundamental role in each of the three modules. The ODF algorithms estimate the model parameters by minimizing the square sum of the shortest distances between the model feature and the measurement points. We demonstrate the performance of the software on a variety of point clouds generated by laser radar, computer tomography, and stripe-projection method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 C
• /
• pp.1451-1453
• /
• 2003

Shrink fitting is often used to replace conventional mechanical fasteners and fastening methods. Localized heating of the mating surface provides temporary expansion and allows slip fit assembly. The resulting interference fit exhibits exceptional strength without surface deformation at ambient temperatures. We studied an analysing method to find out a deformation of motor axis with shrink fitting of thermal expansion.

• 소성∙가공
• /
• 제27권1호
• /
• pp.54-59
• /
• 2018

In connecting parts of a hydrogen fuel cell vehicle, since the rubber ring is permeable to hydrogen, it is necessary to use a metal sealing structure which ensures leakage stability. Finite element analysis was performed to verify the fitting characteristics of the metal sealing structure, which is used to connect the pipe to a high pressure hydrogen FCEV tank. Deformation shape, contact distance and axial load were compared experimentally and these values were in agreement with each other. In the contact surface, between the pipe and the fitting body, the stress at the edge of the contact surface was higher than the center point, which was considered to be a good characteristic in view point of the leakage. The location of the contact points has almost no change in the upper part of the fitting, but that of the lower parts move downward as the fastening amount increases. The contact pressure at the lower part is maintained at the same constant level.

• 한국임상보건과학회지
• /
• 제9권1호
• /
• pp.1462-1468
• /
• 2021

Purpose; The purpose of this study is to objectively identify and quantify the wearer's feelings of wearing glasses. Methods: The temperature of the skin on the nose ridges and ear, and the area where the glasses were seated, was measured using a thermal imaging camera. Results: Before wearing the glasses, the temperature of the skin surface on the nasal ridge was 34.908 ± 0.875 ℃ and the temperature of the ear region was determined as 31.981 ± 0.549 ℃. The changed temperature measured at 5 minutes later after taking off the glasses showed that the nasal ridge was determined as 35.467 ± 0.342 ℃ and the ear area was determined as 32.994 ± 0.412 ℃ (p<0.05). Conclusions: In this experiment, it was revealed that the glasses cause discomfort and heat in the fitting area. It was the first attempt to study objectively and scientifically. Analysis of frame fitting points by using thermal camera is expected to be helpful when consulting a sensitive person about changes in the fit of glasses.