• 대한치과보철학회지
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• 제36권1호
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• pp.133-149
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• 1998

Clinical application of composite resin recently draw great concerns in dentistry. Especially due to advantages such as esthetics, adhesiveness, simple clinical procedures, various shapes and kinds of composite resins are widely being applied to prosthodontics, conservative dentistry, and orthodontics. But, clinical problems attributable to the polymerization shrinkage of composite resin have been proposed, and we have to regard clinical problems such as secondary caries, loss of restoration, fracture of the surrounding tooth structure, marginal discoloration, and tooth sensitivity, and many portions are remained to be overcome. Therefore, this study attempts to analyze stress distribution between resin and tooth structure which is generated during polymerization shrinkage of composite resin using three dimensional finite element method. Three dimensional finite element models with conventional box-shape cavity and erosion/abrasion type V-shape lesion cavity in upper central incisor were developed. These cavities were filled with four different types of placement techniques. (bulk filling, horizontal increment filling, oblique occlusal increment filling, oblique gingival increment filling) The stresses generated by polymerization shrinkage of composite resin were calculated. The results analyzed with three dimensional finite element method were as follows : 1. The increment filling technique showed the highest maximum normal stress in both conventional box-shape and V-shape cavities and showed a tendency to decrease after complete polymerization. 2. The bulk filling technique resulted in increased stresses during the curing process in both conventional box-shape and V-shape cavities and the highest maximum normal stress occurred after complete polymerization. 3. The bulk filling resulted in the lowest maximum normal stress in both box-shape and V-shape cavities 4. Regardless of placement method, in conventional box-shape cavity, the maximum normal stress increased in dentin floor, enamel, dentin sequence and in V-shape cavity, the maximum normal stress increased in enamel, dentin sequence.

• 한국정밀공학회지
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• 제14권9호
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• pp.101-107
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• 1997

A sectional analysis of auto-body panel stamping is carried out by using the rigid-plastic FEM based on the membrane theory. The auto-body panel material is assumed to possess normal anisotropy and to obey Hill's new yield criterion and its associated flow rule. A method of contact treatment is proposed in which the skew boundary condition for arbitarily shaped tools is successively used during iteration. Deformation of each section of trunk-lid panel is simulated and composed to get the three-dimensional shape by using CAD technique. It was shown that the composition of the two-dimensional section analysis gives almost the same results as the full three-dimensional analysis.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.615-626
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• 2010

The discrete-layer model is proposed to analyze the edge-effect problem of laminates under extension and flexure. Based on three-dimensional elasticity theory, the displacement fields of each layer in a laminate have been treated discretely in terms of three displacement components across the thickness. The displacement fields at bottom and top surfaces within a layer are approximated by two-dimensional shape functions. Then two surfaces are connected by one-dimensional high order shape functions. Thus the p-convergent refinement on approximated one- and two-dimensional shape functions can be implemented independently of each other. The quality of present model is mostly determined by polynomial degrees of shape functions for given displacement fields. For nodal modes with physical meaning, the linear Lagrangian polynomials are considered. Additional modes without physical meaning, which are created by increasing nodeless degrees of shape functions, are derived from integrals of Legendre polynomials which have an orthogonality property. Also, it is assumed that mapping functions are linear in the light of shape of laminated plates. The results obtained by this proposed model are compared with those available in literatures. Especially, three-dimensional out-of-plane stresses in the interior and near the free edges are evaluated and convergence performance of the present model is established with the stress results.

• 복식
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• 제58권6호
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• pp.35-41
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• 2008

The purposes of this study lied in the analysis and classification of neck-base circumference shapes of the women in their twenties, by the application of three-dimensional automatic measurement data of human body, and thereby in the understanding of neck-base circumference shapes by the classified type. The findings are as follows: 1. The comparison of three-dimensional human body measurement items relating to the neck-base circumference part of the women in their twenties indicated that the largest individual difference was found in cervicale-center-anterior neck radius than in other items. 2. The factor analysis, which was conducted to extract the factors constituting the neck-base circumference, showed the shape of cervicale(factor 1), the shape of section neck(factor 2), the thickness of neck(factor 3), the shape of anterior neck(factor 4), and the shape of side neck(factor 5). 3. The classification of the neck-base circumference shapes resulted in three types. Type 1 was the shape of a reverse triangle hanging forward, Type 2 was that of a circle, and Type 3 was that of an oval open to the sides.

• 한국디지털건축인테리어학회논문집
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• 제11권2호
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• pp.61-70
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• 2011

This study aims to establish the concept about a new approaching method dor remodeling in the planning step. also, this study sets up the way how to approach in a dimensional way by classifying the conceptual composition of the target housing as a method. The dimensional definition is as below. The one dimensional approach: the spot. the two dimensional approach: the line, the three dimensional approach: the apatial mass, the four dimensional approach: space + time, the n dimensional (multi-dimensional) approach: the space + time + emotion. The research findings are as follows : For the purpose of remodeling, the old housing should be viewed in the three dimensional shape and space. It is defined as multi-dimensional module method to design the shape and space of the target housing in a multi-dimensional point, considering the three dimensional space composition, the emotion of the user, the housing itself. and the time of the user.

• Journal of Biosystems Engineering
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• 제17권1호
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• pp.37-44
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• 1992

This study was intended to develop the design program of the working surface of moldboard-plow by use of the computer-aided design. The mathematical model of the working surfaces of moldboard-plows by use of computer graphics was developed and plotted in two dimension on three major planes. The surfaces of moldboard-plows were represented with "B-spline surface fitting" by selecting the twenty-five three-dimensional data that could well describe the working surface of moldboard-plow. The shape of moldboard-plow on three major planes was drawn for varied design parameters. The representation of the mathematical model for the working surfaces of various types of moldboard-plows was manipulated by translation, rotation and scaling about arbitrary axes in space. By using three-dimensional graphics techique to describe moldboard-plows, it was capable of plotting the three-dimensional shape of moldboard-plow easily and quickly in comparison with the existing design methods that were difficult to grasp the shape of moldboard-plow as a whole. The design theories of moldboard plow and three-dimensional computer graphic technique were applied to find out the improved reversible Jaenggi bottom. It was resulted in the newly developed shape of Jaenggi which may be used for improving the performance compared to existing ones.

• 소성∙가공
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• 제11권4호
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• pp.323-331
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• 2002

The combination of rapid prototyping(RP) and rapid tooling(RT) has a potential for rapid manufacturing of three-dimensional parts. In the present study, a new RP system transfer type Variable Lamination Manufacturing using Expandable Polystyrene Foam (VLM-ST), is proposed to fabricate net shapes of three-dimensional prototypes. Various three-dimensional parts, such as a knob shape and a human head shape, are manufactured by the VLM-ST apparatus. In addition, a new rapid tooling technology, which utilizes a room temperature vulcanizing (RTV) molding technique and a triple reverse process technique, is proposed to manufacture net shapes of three-dimensional plastic parts using the prototypes of VLM-ST. A plastic part of the knob shape is produced by the proposed RT technology. The combination of the proposed RP and RT enables the manufacture of a plastic knob within two days.

• Fibers and Polymers
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• 제7권1호
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• pp.57-61
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• 2006

A study has been made on the quantification and evaluation of fabric pilling using two-dimensional and three-dimensional hybrid imaging methods. Two-dimensional imaging method was good for some samples while three-dimensional measurement method for others, according to the properties of their base fabric. Various image processing techniques as well as three-dimensional data processing algorithms were applied for the extraction of pills from measured data and a series of shape parameters have been defined for the objective evaluation of fabric pilling. An evaluation criterion that is compatible with the conventional evaluation method has been proposed by applying the new evaluation method to the current photographic standards.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.127.4-127
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• 2001

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. A number of visual or optical technologies have been successfully applied to measure three dimensional surfaces. Especially, the shape measurement using an interferometric principle becomes a successful methodology. However, those conventional interferometric methods to measure surface profile have an inherent shortcoming, namely 2∏ ambiguity problem. The problem inevitably happens when the object to be measured has discontinuous shape due to the repetition of interferometric signal with phase period of 2∏. Therefore, in this paper, we choose as a shape measuring method, ...

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.461-464
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• 2003

A new control volume finite element method is proposed for three dimensional analysis of polymer flow. Tetrahedral finite element is employed and co-located interpolation procedure for pressure and velocity is implemented. Inclusion of pressure gradient term in the velocity shape functions prevents the checkerboard pressure field from being developed. Vectorial nature of pressure gradient is considered in the velocity shape function so that velocity profile in the limit of very small Reynolds number becomes physically meaningful. The proposed method was verified through three dimensional simulation of pipe flow problem for Newtonian and power-law fluid. Calculated pressure and velocity field showed an excellent agreement with analytic solutions for pressure and velocity. Driven-cavity problem, which is reported to yield checkerboard pressure filed when conventional finite element method is applied, could be solved without yielding checkerboard pressure field when the proposed control volume finite element method was applied. The proposed method could be successfully applied to the three dimensional mold filling problem.