• Composites Research
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• v.37 no.4
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• pp.301-309
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• 2024

Shape memory stents are used for treating vascular conditions like myocardial infarction, angina, and arteriosclerosis through their shape memory behavior. These stents are inserted into blood vessels to expand them, and their performance in terms of flexibility, elastic recovery, and deformation is influenced by their design. In this study, parameters affecting stent structural design were analyzed using Taguchi method, aiming to design structures that consider flexibility, elastic recovery, and deformation. Reflecting the actual conditions faced by stents, ISO standards were incorporated, and finite element analysis was conducted, considering shape memory composite material properties obtained from tensile tests, specifically hyperealstic properties. Ultimately, statistical significance of stent structural design was evaluated through ANOVA (Analysis of Variance), and an improved optimal design model compared to the existing one was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.61-70
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• 1985

In this paper, the analysis of plates resting on Winkler's springs and on an isotropic elastic half space is made by the finite element method using an isoparametric element. A new technique is introduced to calculate the numerical values of influence area for the soil element. A computer program NMAT has been developed and checked through demonstrating examples.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.115-121
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• 2006

Geometries, boundary renditions, loading renditions and mechanical properties are essential for finite element analysis. However it is a very difficult task to obtain In-vivo geometry and mechanical properties of human body. In this study totally 38 kinds of inner organs are segmented using MRI of young male with Korean standard body shape to make a finite element model. And RUS has been used to acquire anisotropic elasticity matrix of the femoral head.

• Restorative Dentistry and Endodontics
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• v.34 no.5
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• pp.442-449
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• 2009

The aim of this study was to examine that thick dentin bonding agent application or low modulus composite restoration could reduce stresses on dentin bonding agent layer. A mandibular first premolar with abfraction lesion was modeled by finite element method. The lesion was restored by different composite resins with variable dentin bonding agent thickness ($50{\mu}m$, $100{\mu}m$, $150{\mu}m$). 170N of occlusal loading was applied buccally or lingually. Von Mises stress on dentin bonding agent layer were measured. When thickness of dentin bonding agent was increased von Mises stresses at dentin bonding agent were decreased in both composites. Lower elastic modulus composite restoration showed decreased von Mises stresses. On root dentin margin more stresses were generated than enamel margin. For occlusal stress relief at dentin boning agent layer to applicate thick dentin bonding agent or to choose low elastic modulus composite is recommended.

• Computational Structural Engineering
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• v.10 no.1
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• pp.201-211
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• 1997

A clearly consistent finite element formulation for geometrically non-linear analysis of space frames is presented by applying incremental equilibrium equations based on the updated Lagrangian formulation and introducing Vlasov's assumption. The improved displacement field for symmetric cross sections is introduced based on inclusion of second order terms of finite rotations, and the potential energy corresponding to the semitangential rotations and moments is consistently derived. For finite element analysis, elastic and geometric stiffness matrices of the space frame element are derived by using the Hermitian polynomials as shape functions. A co-rotational formulation in order to evaluate the unbalanced loads is presented by separating the rigid body rotations and pure deformations from incremental displacements and evaluating the updated direction cosines of the frame element due to rigid body rotations and incremental member forces from pure deformaions. Finite element solutions for the spatial buckling and post-buckling analysis of space frames are compared with available solutions and other researcher's results.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.145-157
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• 2008

Load transfer efficiency (LTE) reflects the structural performance of doweled and undoweled joints of Jointed Concrete Pavement (JCP). A 3-dimensional (3-D) model of JCP was built using ABAQUS software in this study. Three concrete slabs were placed on bonded sublayers composed of a base and subgrade. Spring elements were used to connect the adjacent slabs at joints. Different spring constants were input to the model to simulate different joint stiffness of the concrete pavement. The LTE of the joint increased with an increase of the spring constant. The effects of material properties and geometric shape on the behavior of JCP were analyzed using different elastic modulus and thickness of the slab and base in the modeling. The results showed the elastic modulus of the subgrade affected the behavior of the slab and LTE more than that of the base and the thickness of the slab and base. The effects of a negative temperature gradient on the behavior of the slab and LTE were more than that of positive and zero temperature gradients. Joints with low stiffness were more sensitive to the temperature gradient of the slab.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.197-207
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• 2000

A transient heat transfer analysis and thermo-elastic analysis have been performed for the residual stress distribution on the fillet weldment used by finite element method. Specimen is fabricated single-pass fillet welding. This computation was performed for conditions including surface heat flux and temperature dependent thermo-physical properties using by heat input as parameter. Also, cut-off temperature of residual stress estimation by thermo-elastic analysis is determined. The fillet weldment were measured to determined their residual stress distributions for using hole-drilling method. As result, it was found that large tensile residual stress is about material yield strength, and the numerical simulation results for finite element method similar to residual stresses by hole-drilling method and other exiting research. Also, cut-off temperature is effectively determined by temperature which calculated maximum thermal stress equal to material yield strength.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.113-124
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• 2001

이 연구는 철근콘크리트 구조물의 비탄성 거동을 파악하고 합리적이면서 경제적인 내진설계기준의 개발을 위한 자료를 제공하는데 그 목적이 있다. 정학하고 올바른 내진성능의 파악을 위하여 비탄선 해석프로그램을 사용하였다. 사용된 프로그램은 철근콘크리트 구조물의 해석을 위해서 유한요소법을 이용하여 개발된 RCAHEST이다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축 전단모델과 콘크리트 소에 있는 철근모델을 조합하여 고려하였다. 이에 대한 콘크리트 균열모델로서는 분산균열모델을 사용하였다. 또한, 횡방향 구속철근으로 인한 강도의 증가 효과를 고려하였다.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.634-637
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• 2010

본 논문은 미세구조의 마이크로 액추에이터의 구동해석을 위한 결과로써 3차원 유한요소해석(Finite Element Analysis, FEA)을 이용하여 수행하였다. 마이크로머신과 같은 미소구조물을 해석하는 경우, 컴퓨터의 메인 프로세스에 비해 프리프로세서(pre-processor)의 비중이 높아지고 있어 그 효율화가 가장 중요하다. 수작업에 의존해야 했던 지난날의 요소분할법 기술은 최근에 들어 여러 연구자들에 의해 개발되고 있다. 특히, 복합현상을 다루는 정전 액추에이터에 직접적인 적용에 다소 어려움이 있는데 3차원적인 수치 및 실험평가는 실용적인 문제에서 비추어 볼 때 매우 중요하다. 따라서 본 논문에서는 센서로서의 역할을 하는 마이크로 정전 액추에이터의 기본설계를 위한 토대를 구축하고자 3차원적인 FEA 시뮬레이션을 수행하여 미세 회전운동을 분석하였다. 그 결과 설계된 모델에서 먼저 자중해석과 Mode 해석에서 기준치를 모두 만족하였다. 또한 설계된 액추에이터의 형상에 따른 회전자의 변형해석을 수행하여 시작토오크와 탄성한계까지의 위치제어에 필요한 회전각을 구하였으며, 정전장 해석을 통하여 시작토오크는 전압 $V^2$에 비례함을 알 수 있었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.709-717
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• 2007

This paper discussed on the effect of an intermediate support on the stability of a beam resting on elastic foundation subjected to follower force. The stability and dynamic responses of a beam resting on elastic foundation subjected to follower force are analyzed based on the finite element method. The dynamic responses of the system are studied by the mode superposition method to observe the damping rate of the motion. The beam resting on elastic foundation subjected to follower force loses its stability by flutter type or divergence type, depending on the location of the intermediate support.