• 정보저장시스템학회논문집
• /
• 제11권2호
• /
• pp.36-40
• /
• 2015

The demand for flexible devices including solar cells, memories and batteries has increased rapidly over the past decades. In most flexible devices, polymer-based materials are used to enable the mechanical deformations such as bending or folding. Shape Memory Polymers (SMPs) is a high molecular compound polymer with flexibility and shape recovery characteristics. In this work, flexible shape memory device was fabricated by simply coating the conducting material, carbon nano-tube (CNT), on a shape memory polymer. Furthermore, durability of the device under various type of mechanical deformations was assessed. It is believed that the result of this work will aid in realization of a stretchable and wearable electronic device for practical applications.

• 대한조선학회논문집
• /
• 제49권1호
• /
• pp.93-98
• /
• 2012

In this study, we introduced image processing technic to measure shape variations of general bodies and applied it to the flexible yacht sail. Shape measurements of simple bodies sails were carried out and results showed that technic can be a reliable method to measure shape variations of the flexible yacht sail. The sail shape variation of 30ft sloop type yacht sail is measured on different sailing conditions. As velocity and direction of wind are increased, trailing edges in the upper part of the sail become more open than the lower part of the sail which are not changed. So it is confirmed that the shape measurement of a sail shape depending on a sailing condition is possible to use image processing scheme.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
• /
• pp.151-160
• /
• 2004

Genetic algorithm is the theory of grafting the principle of survival of the fittest in genetics on to the computer algorithm and it is used to solve the optimization problems, especially the shape and size optimization of the structure in Architectural problems. In the size optimization problem discrete variables are used, but series variables have to be used in the shape optimization problem because of the incongruenty. The purpose of this study is to obtain the optimum shape of cable domes by using the real coding genetic algorithm. Generally, the structural performance of the cable domes is influenced very sensitively by pre-stress, geometry and length of the mast because of its flexible characteristic. So, it is very important to decide the optimum shape to get maximum stiffness of cable domes. We use the model to verify the usefulness of this algorithm for shape optimization and analyze the roof system of Seoul Olympic Gymnastic Arena as analytical model of a practical structures. It is confirmed lastly that the optimum shape domes have more stiffness than initial shape ones.

• 한국CDE학회논문집
• /
• 제9권4호
• /
• pp.306-314
• /
• 2004

This paper explains the qualitative shape representation scheme and general shape analysis procedure based on shape feature categories. It takes two different groups of architectural drawings as examples and comparer them so as to confirm that the procedure is capable of comparing one group with another. In order to verify the validity of qualitative shape representation scheme, we used statistical methods as well as symbolic representation and analysis techniques. This paper concludes that two different groups of architectural drawings of similar kind are analyzed to be distinguished and specifically characterized. 11 drawings of Kahn and 13 drawings of Aalto are taken into considerations. Linear regressions are used in characterizing the shape featural relationships.

• 한국정밀공학회지
• /
• 제25권1호
• /
• pp.160-170
• /
• 2008

Shape morphing is the process of transforming a source shape, through intermediate shapes, into a target shape. Two main problems to be considered in three dimensional shape morphing are vertex correspondence and path interpolation. In this paper, an approach which uses the linear interpolation of the Laplacian coordinates of the source and target meshes is introduced for the determination of more plausible path when two topologically identical shapes are morphed. When two shapes to be morphed are different in shape and topology, a new method which combines shape deformation theory based on Laplacian coordinate and mean value coordinate with distance field theory is proposed for the efficient treatment of vertex correspondence and path interpolation problems. The validity and effectiveness of the suggested method was demonstrated by using it to morph large and complex polygon models including male and female whole body models.

• 한국세라믹학회지
• /
• 제43권11호
• /
• pp.728-733
• /
• 2006

The equilibrium or growth shape of ceramic materials is classified largely into two categories according to the thermodynamic conditions imposed. One is a polyhedral shape where the surface free energy is anisotropic, and the other a spherical shape where the surface free energy is isotropic. In the case of grains with a polyhedral shape of anisotropic surface free energy, socalled abnormal grain growth usually takes place due to a significant energy barrier for a growth unit to be attached to the crystal surface. In the case of grains with a spherical shape of isotropic surface free energy, however, normal grain growth with a uniform size distribution takes place. In this contribution, the state-of-the-art of our current understanding of the relationship between the crystal shape and the microstructure evolution during the sintering of ceramic materials in the presence of a liquid phase was discussed.

• 한국정밀공학회지
• /
• 제13권9호
• /
• pp.54-61
• /
• 1996

Because of its high energy density, the use of shape memory alloys(SMA) in designing microactuatiors is gaining much attention in recent years. Shape memory alloys can undergo a shape change at a low temperature with a small applied deformation force, and retain this deformation until they are heated, at which point they return to the original shape. This is called the shape memory effect(SME), and a plethora of alloys show this effect. Among them, TiNi-based alloys have relatively high electrical resistivity, which to develope helical-shape memory springs. These springs are used to develop fast protatonist/antagonist configuration actuators. The developed actuator has an actuation speed of 1 mm per 15 .approx. 20 ms and a minimum operating period of 2 sec.

• Ecology and Resilient Infrastructure
• /
• 제8권4호
• /
• pp.204-211
• /
• 2021

본 연구에서는 3차원 지상 라이다 스캐너를 통해 수집되는 포인트 클라우드를 활용하여 식생의 정보를 수집하였으며, 수집된 데이터를 기반으로 객체를 재구현하여 물리적 형상을 분석하였다. 이를 위해 원시 데이터의 필터링 단계별 최적의 데이터를 구축하였으며, 구축된 데이터를 활용하여 실제 부피와 Alpha Shape 및 Voxel 기법을 활용한 부피 산정 결과를 산정한 후 각각 비교하였다. 분석 결과, Alpha Shape를 적용하여 부피를 산정한 경우 데이터 필터링과 관계없이 실제 부피보다 과다 산정되는 것으로 나타났다. 또한 Voxel 기법을 활용할 경우 8차 필터링 후 실제 부피와 가장 유사한 것으로 나타났으며, 이후 필터링이 진행될수록 실제 부피에 비해 과소 산정되는 것을 알 수 있었다. 따라서 포인트 클라우드를 활용하여 객체를 재구현 할 경우, 대상이 되는 객체의 복잡한 형상으로 인한 내부 공극을 고려해야 하며, 필터링 과정에서 최적의 데이터 구축을 위한 필터링 과정에 반드시 주의할 필요가 있다.

• 대한기계학회논문집A
• /
• 제38권4호
• /
• pp.363-370
• /
• 2014

본 연구에서는 NURBS(Non-Uniform Rational B-spline)를 이용한 형상최적화 방법을 제안한다. 대부분 NURBS 기반 형상 최적화 방법은 NURBS의 제어점 위치 좌표 값만을 설계변수로 택하고 있다. 이러한 경우, 형상최적화 과정에서 종종 제어점들이 서로 가까워져 메쉬 품질을 악화시키고 수렴이 되지 않는 등의 문제를 야기시킨다. 본 연구에서는 형상최적화에서 NURBS 제어점의 좌표뿐 아니라 가중치를 추가적으로 설계 변수로 고려하여 세밀한 형상 변화를 가능하게 하고, 제어점 위치 좌표 최적화 과정과 제어점 가중치 최적화 과정을 분리하여 단계적으로 효율적인 형상 최적화를 수행하였다. 제안한 형상최적화 방법을 예제에 적용하여 제안된 방법의 효율성을 검증하였다.

• Journal of Mechanical Science and Technology
• /
• 제14권8호
• /
• pp.861-866
• /
• 2000

Flow induced shape change is important for spatial interpretation of vascular response and for understanding of mechanotransduction in a single cell. We investigated the possible shapes of endothelial cell (EC) in a mathematical model and compared these with experimental results. The linearized analytic solution from the sinusoidal wavy wall and Stokes flow was applied with the constraint of EC volume. The three dimensional structure of the human umbilical vein endothelial cell was visualized in static culture or after various durations of shear stress (20 $dyne/cm^2$ for 5, 10, 20, 40, 60, 120min). The shape ratio (width: length: height) of model agreed with that of the experimental result, which represented the drag force minimizing shape of stream-lining. EC would be streamlined in order to accommodate to the shear flow environmented by active reconstruction of cytoskeletons and membranes through a drag force the sensing mechanism.