• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.71-74
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• 2003

The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided composites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced composite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained fer two volume fractions.

• 대한산업공학회지
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• 제23권1호
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• pp.215-222
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• 1997

This paper deals with the problem of generating a uniform tetrahedral mesh which fills a 3-D space with the tetrahedra which are close to the equilateral tetrahedra as possible. This problem is particularly interesting in finite element modeling where a fat triangulation minimizes the error of an analysis. Fat triangulation is defined as a scheme for generating an equilateral triangulation as possible in a given dimension. In finite element modeling, there are many algorithms for generating a mesh in 2-D and 3-D. One of the difficulties in generating a mesh in 3-D is that a 3-D object can not be filled with uniform equilateral tetrahedra only regardless of the shape of the boundary. Fat triangulation in 3-D has been proved to be the one which fills a 3-D space with the tetrahedra which are close to the equilateral as possible. Topological and geometrical properties of the fat triangulation and its application to meshing algorithm are investigated.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권3호
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• pp.122-127
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• 2003

This paper presents a new time-stepping 3-D analysis method coupled with an external circuit with motion equation for dynamic transient analysis of induction machines. In this method, the magneto-motive force (MMF) generated by induced current is modeled as a passive source in the magnetic equivalent network. So, by using only scalar potential at each node, the method is able to analyze induction machines with faster computation time and less memory requirement than conventional numerical methods. Also, this method is capable of modeling the movement of the mover without the need for re-meshing and analyzing the time harmonics for dynamic characteristics. From comparisons between the results of the analysis and the experiments, it is verified that the proposed method is capable of estimating the torque, harmonic field, etc. as a function of time with superior accuracy.

• Fibers and Polymers
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• 제4권2호
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• pp.77-83
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• 2003

The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided com-posites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced com-posite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained for two volume fractions.

• Structural Engineering and Mechanics
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• 제72권2호
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• pp.191-201
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• 2019

Finite element analysis is one of the most used tools for studying femoral neck fracture. Nerveless, consensus concerning either the choice of material characteristics, damage law and /or geometric models (linear on nonlinear) remains unreached. In this work, we propose a numerical quasi-brittle damage model to describe the behavior of the proximal femur associated with two methods to evaluate the Young modulus. Eight proximal femur finite elements models were constructed from CT scan data (4 donors: 3 women; 1 man). The numerical computations showed a good agreement between the numerical curves (load - displacement) and the experimental ones. A very encouraging result is obtained when a comparison is made between the computed fracture loads and the experimental ones ($R^2=0.825$, Relative error =6.49%). All specific numerical computation provided very fair qualitative matches with the fracture patterns for the sideway fall simulation. Finally, the comparative study based on 32 simulations adopting linear and nonlinear meshing led to the conclusion that the quantitatively results are improved when a nonlinear mesh is used.

• 한국인터넷방송통신학회논문지
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• 제12권4호
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• pp.153-159
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• 2012

안전하고 쾌적한 도시 환경을 조성하기 위해 폐기물 매립 시설은 필요하며 폐기물 부피 관리의 신뢰성 및 용량 정보의 정확성을 파악하는 것이 필요하다. 이 논문에서는 쓰레기 매립의 표준화를 위한 일환으로 쓰레기 체적을 주기적으로 계산하는 알고리즘을 제시하였다. 스테레오 카메라 캘리브레이션 이후에 대상체의 표면에 대한 포인트 클라우드(point cloud)를 얻을 수 있었으며 이것을 물체의 체적 계산 알고리즘의 입력으로 선택하였다, 비균일 삼각 격자 기반 메싱(non-uniform triangular meshing) 방법에 기초한 두 개의 체적 계산 알고리즘을 제안하였으며 알고리즘의 타당성을 시뮬레이션과 실제 실험을 통해 입증하였다. 제시된 알고리즘은 쓰레기 매립의 체적 계산 뿐 만이 아니라 삼차원 객체의 일반적인 체적 계산을 위한 알고리즘으로도 사용될 수 있다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.184-191
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• 2003

In this paper, a mathematical framework based on a homogenisation technique to simulate 'umbrella arch reinforcement system' (UARS) and its implementation into a 3D Finite Element program that can consider stage construction situations are presented. The constitutive model developed allows considering the main design parameters of the problem and only requires geometrical and mechanical properties of the constituents. Additionally, the use of a homogenisation approach implies that the generation of the Finite Element mesh can be easily produced and that re-meshing is not required as basic geometrical parameters such as the orientation of the pipes are changed. The model developed is used to simulate tunnelling with the UARS. From the analyses, the effects of the main design parameters on the elastic and the elastoplastic analyses are considered.

• 방송공학회논문지
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• 제27권2호
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• pp.207-215
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• 2022

최신 볼류메트릭 기술이 제공하는 높은 기하학적 정확도와 사실성은 실제 객체와 캡춰된 3D 모델 간 높은 일치도를 보장한다. 그럼에도 불구하고 이렇게 획득된 3D 모델은 프레임 간 완전히 독립적인 3D모델로 시퀀스를 구성하고 있다는 측면에서, 매 프레임 모델 표면 구조(Geometry)의 일관성이 보장 되지 않으며, 정점(Vertex)의 밀도가 매우 높고 정점 간 연결 노드(Edge)가 매우 복잡해지는 특징을 확인 할 수 있다. 이 기술을 통해 생성된 3D 모델은 영화나 비디오 게임 제작 파이프라인에서 제작된 모델과는 본질적으로 다르며, 실시간 렌더링, 애니메이션 및 시뮬레이션, 압축과 같은 응용 분야에서 직접 사용하기에 적합하지 않다. 이와는 대조적으로 우리의 방법은 프레임 간 3D 모델 표면 구조의 높은 일관성을 확보하는 리메싱(Remeshing)과 비강체 표면(Non-rigid Shape)의 대응(Correspondences) 및 매칭(Matching)을 통한 점진적 변형(Deformation) 과정 및 텍스쳐 전달(Texture Transfer) 과정을 연결함으로서 볼류메트릭 3D 모델 시퀀스 품질의 일관성을 유지하며, 후 처리 과정의 자동화를 제공한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.365-368
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• 2006

RBSN Method, Rigid-Body-Spring Network Method, is a structural analysis method that overcomes the problems faced in FEM analysis of concrete or crack forming structures. In RBSN, irregular lattices are used to model structural components consisting of bulk material, curvilinear reinforcements, and their interfaces. Because reinforcements and their interfaces in the bulk material are freely positioned, meshing is irrespective of the geometry of the representing bulk material. In this paper, RBSN method of 3D is applied in simulating the pull-out test of FRP (Fiber Reinforced Polymer) embedded in concrete. The comparison of analysis results to experimental results shows that RBSN method simulates the shear-slip behavior very precisely. From the analysis results, 3D RBSN method is proven to be an effective and accurate analysis method for concrete structural analysis. Also, the results show that RBSN method can be a potential analysis method for concrete structures that can replace the current FEM analysis.

• 한국전산구조공학회논문집
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• 제22권4호
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• pp.335-341
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• 2009

본 논문에서는 MLS기반 유한요소에 대한 현재 개발상황에 대한 개관과 향후 예상할 수 있는 응용분야에 대한 제안을 하였다. 이동최소제곱근사를 이용하여 형상함수를 생성하는 MLS기반 유한요소는, 요소의 경계에서 기존 유한요소의 성질-크로네커 델타 조건-을 가지면서도 기존 요소가 갖지 못했던 임의의 절점 추가가 자유롭다는 장점이 있어 다양한 변절점 요소로의 개발이 이루어져 왔다. 선형 또는 이차형상함수를 갖는 2차원 변절점요소 뿐 아니라, 균열선단과 균열면을 포함하고 있는 2차원 균열요소와 3차원에서의 제한적인 변절점요소 등이 개발되어 다양한 불연속성 문제에 적용 가능함이 입증되었다. 이러한 MLS기반 유한요소는 향후 2차원 변절점 3각요소, 2차원 삼각균열요소, 변절점 쉘요소, 균열 쉘요소, 마칭큐브알고리즘에 적합한 3차원 다면체요소로의 개발이 가능할 것으로 예상되며, 본 논문에서는 그 일례로 3차원 다면체요소를 이용한 대퇴골의 요소망 생성을 보였다.