• 한국CDE학회논문집
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• 제1권1호
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• pp.65-75
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• 1996

This paper describes an automatic finite element(FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid and shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid and shell structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권3호
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• pp.228-240
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• 2012

Morphing is a geometric interpolation technique that is often used by the animation industry to transform one form into another seemingly seamlessly. It does this by producing a large number of 'intermediate' forms between the two 'extreme' or 'parent' forms. It has already been shown that morphing technique can be a powerful tool for form design and as such can be a useful addition to the armoury of product designers. Morphing procedure itself is simple and consists of straightforward linear interpolation. However, establishing the correspondence between vertices of the parent models is one of the most difficult and important tasks during a morphing process. This paper discusses the mesh-merging method employed for this process as against the already established mesh-regularising method. It has been found that the merging method minimises the need for manual manipulation, allowing automation to a large extent.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.411-419
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• 2017

The Wireless Mesh Network (WMN) is a multi-hop wireless network consisting of mesh routers and clients, where the mesh routers have minimal mobility and form the backbone. The WMN is primarily designed to access outer network to mesh clients through backhaul gateways. As traffic converges on the gateways, traffic hotspots are likely to form in the neighborhood of the gateways. In this paper, we propose Congestion Aware Multi-path Routing (CAMR) protocol to tackle this problem. Upon congestion, CAMR divides the clients under a mesh STA into two groups and returns a different path for each group. The CAMR protocol triggers multi-path routing in such a manner that the packet reordering problem is avoided. Through simulations, we show that CAMR improves the performance of the WMN in terms of throughput, delay and packet drop ratio.

• 대한소아치과학회지
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• 제32권1호
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• pp.132-135
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• 2005

본 연구의 목적은 유전치 심미수복의 새로운 방법으로 glass fiber를 이용한 강화형 strip crown의 사용을 제시하고자 하는 것이다. Strip crown의 제작을 위하여 celluloid crown form(3M, USA)과 복합레진은 Z100(P shade, 3M, USA)을, 유동성 복합레진은 Aeliteflo(Bisco Inc., USA)를 사용하였다. 상아질 결합제는 Clearfil SE Bond(Kuraray Medical Inc., Japan)를 사용하였고 강화를 위하여 그물형 glass fiber(TESCERA Fiber Mesh, Bisco Inc, USA)를 사용하였다. 적절한 크기의 celluloid crown form을 성형하여 삭제된 치아에 시적한 후 레진 접착제와 유동성 복합레진으로 처리한 그물형 glass fiber를 설측 내면에 삽입하고 광중합하였다. 잔여 공간에 복합레진을 채우고 치아에 끼운 다음 광중합하였다. 복합레진의 심미성은 유지하면서 glass fiber로부터 기계적 장점을 얻을 수 있을 것으로 사료된다. 새로운 강화형 strip crown의 물성에 대한 후속연구가 필요하다.

• Structural Engineering and Mechanics
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• 제45권3호
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• pp.411-422
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• 2013

A well-designed mesh shape of the cable net is of essential significance to achieve high performance of cable-network antenna reflectors. This paper is concerned with the mesh design problem for such antenna reflector structure. Two new methods for creating the topological forms of the cable net are first presented. Among those, the cyclosymmetry method is useful to generate different polygon-faceted meshes, while the topological mapping method is suitable for acquiring triangle-faceted meshes with different mesh grid densities. Then, the desired spatial paraboloidal mesh geometrical configuration in the state of static equilibrium is formed by applying a simple mesh generation approach based on the force density method. The main contribution of this study is that a general technical guide for how to create the connectivities between the nodes and members in the cable net is provided from the topological point of view. With the new idea presented in this paper, multitudes of mesh configurations with different net patterns can be sought by a certain rule rather than by empiricism, which consequently gives a valuable technical reference for the mesh design of this type of cable-network structures in the engineering.

• 한국공간구조학회논문집
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• 제10권2호
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• pp.77-86
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• 2010

본 연구에서는 프리폼(free form)을 가지는 공간구조물의 유한요소망을 자동으로 생성하는 기법을 개발하고 그 배경이론과 수치실험 결과 그리고 이용방안에 대하여 기술하였다. 본 연구를 통하여 제시한 유한요소망 생성기법은 공간구조물의 해석을 위해 전통적으로 이용하던 형태별 자동생성기법의 한계를 극복하기 위하여 개발 되었다. 개발된 자동 생성기법은 최근 연속체 쉘 구조물의 형태를 정확히 구현하기 위해 활발히 이용되고 있는 CAGD기법을 도입하였다. 본 연구에서 제시된 자동생성기법은 두 단계의 생성과정을 거치는데 첫 번째가 구조물의 형태를 기하학적인 모델로 표현하는 단계이며 두 번째가 표현된 기하학적인 모델에 이산화된 공간구조물을 생성하는 단계이다. 수치실험을 통하여 본 연구에서 개발된 자동생성기법이 임의의 형상을 가지는 이산화된 공간구조물을 표현하기 용이할 뿐만이 아니라 기존의 자동생성기법을 수정 이용할 수 있는 장점이 있으며 특히 이산화된 공간구조물의 형상최적화에도 효과적으로 이용될 수 있을 것으로 나타났다.

• 한국정밀공학회지
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• 제12권2호
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• pp.162-172
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• 1995

In this paper new mesh generation method is proposed for crack propagation analysis based on the finite element method. The main tool of the method is the Delaunay Triangulation, Transfinete element mapping, and it allows the setting of the arbitrary crack-growth increment and the arbitrary crack direction. It has the form of a subroutine, and it is easily introduced as a subroutine for any mesh generation method which is based on the blocking method.

• International Journal of CAD/CAM
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• 제1권1호
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• pp.11-21
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• 2002

This paper presents a triangular-to-quadrilateral mesh conversion method that can control the directionality of the output quadrilateral mesh according to a user-specified vector field. Given a triangular mesh and a vector field, the method first scores all possible quadrilaterals that can be formed by pairs of adjacent triangles, according to their shape and directionality. It then converts the pairs into quadrilateral elements in order of the scores to form a quadrilateral mesh. Engineering analyses with finite element methods occasionally require a quadrilateral mesh well aligned along the boundary geometry or the directionality of some physical phenomena, such as in the directions of a streamline, shock boundary, or force propagation vectors. The mesh conversion method can control the mesh directionality according to any desired vector fields, and the method can be used with any existing triangular mesh generators.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.688-692
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• 2008

3차원 아바타 시스템에서 아이템들은 아비타의 체형마다 맞춰서 제작하여야 한다. 이러한 제작방식은 사업적인 측면에서 불리한점이 클 뿐만 아니라, 서비스하는 아바타의 체형, 종류와 같은 다양성 측면에서도 소비자의 욕구를 만족하기 어렵다. 다양한 체형의 아비타를 서비스하기 위해 제작해야 할 작업량은 기하급수적으로 늘어날 수밖에 없다. 본 연구는 아바타의 제형을 최소한의 데이터 제작으로 표현가능 하도록 메쉬모핑(mesh morphing) 기법을 활용한 3D 아바타 체형변형방법에 관한 것이다. 아바타의 기본제형과 변형될 체형을 토대로 실시간으로 표현할 수 있는 중간체형을 생성하는 방법과 기본체형에 맞게 제작된 의상, 헤어스타일, 신발 등 아바타 아이템 들을 중간체형에 맞도록 자동으로 변형하는 방법을 소개한다. 제시한 방법을 이용하면, 새로운 체형의 아바타를 도입하더라도 기 제작된 아이템들의 추가 제작 없이 새로운 체형에 맞는 아이템을 서비스할 수 있음을 보여준다. 또한 새로운 체형의 표현 방법이 실시간으로 적용할 수 있는 방직임을 보여준다.

• 디지털산업정보학회논문지
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• 제5권3호
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• pp.117-126
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• 2009

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., This paper presents a secure and efficient authentication mechanism for Wireless mesh network. The validity of proposed mechanism is provided by BAN logic and the efficiency of suggested mechanism is showed through the performance evaluation.