• Korean Journal of Human Ecology
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• v.21 no.3
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• pp.539-550
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• 2012

In-depth knowledge of fabric microstructure is essential for understanding clothing comfort since it plays a significant role in heat and mass transfer between the human body and clothing. In this study, a novel method was employed for investigating 3D surfaces and solid construction characteristics of specific fabrics by using a reverse engineering technique. The surface construction data were obtained by a confocal laser scanning microscope and then manipulated by a 3D analysis program. Triangle mesh was used for connecting each 3D point, with clouds and fabric surface characteristics created by rendering techniques. For generating a 3D solid model, determinants of radius of curvature was used. According to the proposed method, actual surface expression of the real fabric was achieved successfully. The results from this methodology can be applied to the detailed analysis of clothing comfort that is highly influenced by the microstructure of the fabric.

• The Journal of Advanced Prosthodontics
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• v.15 no.3
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• pp.145-154
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• 2023

PURPOSE. The objective of this study was to investigate how internal structures influence the overall and marginal accuracy of full arch preparations fabricated through additive manufacturing in different printing systems. MATERIALS AND METHODS. A full-arch preparation digital model was set up with three internal designs, including solid, hollow, and grid. These were printed using three different resin printers with nine models in each group. After scanning, each data was imported into the 3D data processing software together with the master cast, aligned and trimmed, and then put into the 3D data analysis software again to compare the overall and marginal deviation whose results are expressed using root mean square values and color maps. To evaluate the trueness of the resin model, the test data and reference data were compared, and the precision was evaluated by comparing the test data sets. Color maps were observed for qualitative analysis. Data were statistically analyzed by one-way analysis of variance and Bonferroni method was used for post hoc comparison (α = .05). RESULTS. The influence of different internal structures on the accuracy of 3D printed resin models varied significantly (P < .05). Solid and grid models showed better accuracy, while the hollow model exhibited poor accuracy. The color maps show that the resin models have a tendency to shrink inwards. CONCLUSION. The internal structure design influences the accuracy of the 3D printing model, and the effect varies in different printing systems. Irrespective of the kind of printing system, the printing accuracy of hollow model was observed to be worse than those of solid and grid models.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.387-392
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• 2001

This paper is to model a 30-shape product applying mathematically the data acquired from a 3D scanner and using an Automatic Design Program. The research studied in th reverse engineering up to now has been developed continuously and surprisingly. However, forming 3D-shape solid models in CAE and CAM, based on the research, the study leaves much to be desired. Especially, analyses and studies reverse-designing automatically using measured data after manufacturing. Consequently, we are going to acquire geometric data using an 3D scanner in this study with which we will open a new field of reverse engineering by a program which can design a 3D-shape solid model in a CAD-based program automatically.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.1
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• pp.47-56
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• 2015

In this paper, we present an implicit method for reconstructing a 3D solid model from two 2D cross section images. The proposed method is based on the Cahn-Hilliard model for the image inpainting. Image inpainting is the process of reconstructing lost parts of images based on information from neighboring areas. We treat the empty region between the two cross sections as inpainting region and use two cross sections as neighboring information. We initialize the empty region by the linear interpolation. We perform numerical experiments demonstrating that our proposed method can generate a smooth 3D solid model from two cross section data.

• Interaction and multiscale mechanics
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• v.3 no.2
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• pp.192-211
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• 2010

In most framed structures the nonlinearities and the damages are localized, extending over a limited length of the structural member. In order to capture the details of the local damage, the segments of a member that have entered the nonlinear range may need to be analyzed using the three-dimensional element (3D) model whereas the rest of the member can be analyzed using the simpler one-dimensional (1D) element model with fewer degrees of freedom. An Element-Coupling model was proposed to couple the small scale solid 3D elements with the large scale 1D beam elements. The mixed dimensional coupling is performed imposing the kinematic coupling hypothesis of the 1D model on the interfaces of the 3D model. The analysis results are compared with test results of a reinforced concrete pipe column and a structure consisting of reinforced concrete columns and a steel space truss subjected to static and dynamic loading. This structure is a reduced scale model of a direct air-cooled condenser support platform built in a thermal power plant. The reduction scale for the column as well as for the structure was 1:8. The same structures are also analyzed using 3D solid elements for the entire structure to demonstrate the validity of the Element-Coupling model. A comparison of the accuracy and the computational effort indicates that by the proposed Element-Coupling method the accuracy is almost the same but the computational effort is significantly reduced.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.3
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• pp.255-260
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• 2002

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-coded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete finite element(FE) model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, semi-elliptical surface cracks in a inhomogeneous plate subjected to uniform tension are solved.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.91.1-91
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• 2002

1. Introduction Present study presents the basic concept of a Solid Freeform Fabrication System using a rapid prototyping procedure and optimal control for a transferring and accumulating system. And it developed a novel rapid prototyping process that can use ceramic or metal as well as polymer as a basic material. 2. Solid Freeform Fabrication System 2.1 Basic Theory A 3D CAD data of the model is converted to the 2D cross-section data of the slides. A ceramic or metal tape of thickness 0.5-1.5mm is cut by a laser beam with the cross-section data of the slide. A 3D model was obtained by transferring and accumulating the slides. The final product is manufactured by sin...

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.367-372
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• 2001

Feature restoration is that restore feature to 3D solid model using the feature information in STEP AP224. Feature is very important in CAPP, but feature information is defined very complicated in STEP AP224. This paper recommends the algorithm of extraction the feature information in physical STEP AP224file. This program import STEP AP224 file, parse the geometric and topological information, the tolerance data, and feature information line-by-line. After importation and parsing, store data into database. Feature restoration module analyze database including feature information, extract feature information, e.g. feature type, feature's parameter, etc., analyze the relationship and then restore feature to 3D solid model.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.17-18
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• 2015

In manufacturing industry, image scanning technique has made enormous progress in past decades. 3D models have been also very important to continuously monitor the related spatial information for freeform buildings. The process of shape making of 3D scanning is as follows: mesh surface segmentation, NURBS surface generation, and parametric solid model generation. We will review the process and applying process. Especially in the construction industry, 3D data collection by laser scanning has become an high quality 3D models. Therefore, in this research, we have an effort to review construction of reverse design process for freeform envelope using 3D scanning. The technology enables many 3D shape engineering and design parameterization of reverse engineering in the construction site.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.8-11
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• 2002

In this study, Automatic design program creates 3D solid models and constructs them. The method of making assembly model is two. One assembles the element made in automatic design program with hand, the other develops the automatic design program for creating assembly model. Automatic design program improves the convenience of user. In creating gears, involute ewe and Trochoidal fillet curve are made by mathematical development.