• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제17권3호
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• pp.139-170
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• 2013

We extend a p-hierarchical decomposition of the second degree finite element space of N$\acute{e}$d$\acute{e}$lec for tetrahedral meshes in three dimensions given in [1] to meshes with hexahedral elements, and derive p-hierarchical decompositions of the second degree finite element space of Raviart-Thomas in two dimensions for triangular and quadrilateral meshes. After having proved stability of these subspace decompositions and requiring certain saturation assumptions to hold, we construct a local a posteriori error estimator for fem and bem coupling of a time-harmonic electromagnetic eddy current problem in $\mathbb{R}^3$. We perform some numerical tests to underline reliability and efficiency of the estimator and test its usefulness in an adaptive refinement scheme.

• 대한기계학회논문집A
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• 제35권9호
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• pp.1091-1097
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• 2011

SGBEM-FEM 교호법은 유한 물체 내에 존재하는 삼차원 균열을 해석하는 유용한 방법으로 알려져 있다. 이 방법으로 일반적인 평면 혹은 비평면 삼차원 균열에 대한 정확한 응력강도계수를 구할 수 있다. 기존의 방법에서는 균열을 모델화 하는데 8 절점 사각형 경계요소를 사용한다. 그러나 임의 형상의 균열의 경우는 3 절점 삼각형 요소를 사용하여 균열을 모델화 하는 것이 더 편리하다. 따라서 본 논문에서는 3 절점 삼각형 요소와 7 절점 사각형 요소를 사용하여 전진 프런트 법으로 균열을 모델링 하였다. 사용된 균열 모델의 정확성을 검토하기 위하여 몇 가지 형상의 균열에 대하여 응력강도계수를 구하여 기존의 해와 비교하였다.

• Computers and Concrete
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• 제11권5호
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• pp.475-492
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• 2013

Since the beginning of the 90 s, depending on the growth of the industrial sector in Turkey, factory constructions have been increased. The cost of precast concrete buildings is lower than the steel ones for this reason the precast structural systems are used more. Precast concrete structural elements are mostly as strong as not to have damage in the earthquake but weakness of connections between elements causes unexpected damages of structure during earthquake. When looking at the previous researches, it can be seen that there is a lack of studies about socket type base connections although there were many experimental and analytical studies about the connections of precast structural elements. The aim of this study is to investigate the stress transfer mechanism between column and the socket base wall with finite element method. For the finite element analysis ANSYS software was used. A finite element model was created which is the simulation of experimental research executed by Canha et al. (2009) under vertical and horizontal forces. Results of experimental research and finite element analysis were compared to create a successful simulation of experimental program. After determining the acceptable parameters, models of socket bases were created. Model dimensions were chosen according to square section column sizes 400, 450, 500, 550 and 600 mm which were mostly used in industrial buildings. As a result of this study, stress distribution at center section of the socket base models were observed and it is found that stress distribution affects triangular at the half of socket bottom and top.

• 한국재료학회지
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• 제31권8호
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• pp.433-438
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• 2021

In this study, microstructural characteristics and constituent elements of fiberglass splint and cast are examined using a scanning electron microscope and an energy dispersive X-ray spectrometer. As observed by the scanning electron microscope, fiberglass splint and cast had a porous structure with many bundles of fiberglass textures well assembled. Spaces between bundles of the fiberglass splint are triangular or elliptical shaped and the long-axis diameter is measured at about 1 mm. The thickness of fiber bundles covered with plaster is measured at 600 ㎛ and the diameter of a single strand of fiberglass is up to 10 ㎛. The thickness of the fiberglass bundle of the fiberglass splint is measured at about 700 ㎛. Spaces between bundles are formed in the shape of triangles with gentle edges and long-axis diameter of up to 1.4 mm, which is larger than that of the splint. The thickness of a single strand of fiberglass of the plaster-coated cast is 11.5 ㎛, which is thicker than that of fiberglass of the splint. As a result of analyzing constituent elements of the fiberglass cast and the splint with an energy dispersive X-ray spectrometer, Ca, Si, and Al components are identically detected. This result shows that the fiberglass cast has a smoother surface with hardened plaster than the fiberglass splint. The thickness of the fiberglass bundle and the thickness of a single strand of the fiberglass are also larger than those of the fiberglass splint.

• 한국항공우주학회지
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• 제46권3호
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• pp.210-218
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• 2018

항공기와 같은 복잡한 구조물의 유한요소해석을 위해 자동요소망을 생성하면 일반적으로 삼각형 요소가 많이 생성되게 된다. 하지만 삼각형 요소는 사각형 요소에 비해 정확도가 떨어지므로 신뢰성 있는 해를 도출하기 어렵다. 이와 같은 문제는 배경셀 적분을 이용한 무요소법(Meshfree Method)을 통해 개선할 수 있으나 이 또한 적분점의 과다사용, 적분영역의 비효율성 등의 문제가 발생하게 된다. 이를 개선하기 위해 절점 기준으로 적분영역을 설정하여 적분을 수행하는 방법이 제안되었지만 비압축성 문제의 경우 해의 진동현상이 일어나는 등 수치 정확도가 떨어지게 된다. 따라서 본 연구에서는 적분영역을 절점영역이 아닌 요소영역으로 설정하는 수정된 무요소법을 통해 요소의 형태에 따른 정확도 저하가 발생되지 않고 기존의 무요소법에서 발생되는 수치 불안정성 등을 개선하였다. 2차원 예제를 통해 수정된 무요소법의 효용성을 검증하였다.

• 대한지구과학교육학회지
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• 제9권2호
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• pp.186-198
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• 2016

연구의 목적은 예비 지구과학 교사들이 이해하고 있는 암석 순환의 구성요소와 과정에 대해 밝히는 것이다. 남부 지역에 소재한 사범대학교 2학년에 재학하면서 지구과학 수업을 수강하는 25명의 예비교사들이 연구대상으로 선정되었다. 암석 순환의 구성요소들을 구조적으로 배열하고, 순환 방향을 화살표로 표시하고, 순환 과정에 대해 서술하는 방법을 적용하였다. 예비교사들이 이해하는 암석순환의 구성요소는 마그마, 화성암, 변성암, 퇴적물, 퇴적암의 5가지로, 순환의 과정은 20가지로 표현되었다. 순환의 유형은 선형, 삼각형, 원형, 복합형의 4가지 기준으로 분석되었으며, 일부 예비교사들은 순환의 고리를 완성하지 못하거나 한 방향의 단순한 순환 구조로 시스템적이지 못한 이해를 표출하였다. 암석 순환은 역동성과 복잡성으로 특징되는 지구계 교육의 주제로서 중요한 의미가 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.289-294
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• 2002

In this study, performance, flow characteristics and noise of a cross-flow-fan system, used in indoor unit of the split-type air conditioner, were predicted by computational simulation. Triangular elements were used to mesh the calculation domain and quadrilateral elements were attached to the blade surfaces and walls to enhance the simulation quality. The unsteady incompressible Wavier-Stokes equations were solved using a sliding mesh technique on the interface between rotating fan region and the outside. Two stripes of velocity stream inside the cross-flow-fan were shown - the one was due to the eccentric vortex and the other was due to the normal entrance flow. As the flow rate increased, the center of the eccentric vortex moved toward the inner blade tip and rear-guide, and the exiting flow still had velocity variation along the stabilizer, which can increase the noise level. The acoustic pressure was calculated by using Lowson's equation. From the calculated acoustic pressure, it was found that the trailing edge is a dominant of acoustic generation.

• Journal of Applied and Pure Mathematics
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• 제5권3_4호
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• pp.237-253
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• 2023

Let a graph G = (V, E) be a (p, q) graph. Define $${\rho}=\{\array{{\frac{p}{2}} & \;\;p\text{ is even} \\ {\frac{p-1}{2}} & \;\;p\text{ is odd,}$$ and M = {±1, ±2, … ± ρ} called the set of labels. Consider a mapping λ : V → M by assigning different labels in M to the different elements of V when p is even and different labels in M to p - 1 elements of V and repeating a label for the remaining one vertex when p is odd. The labeling as defined above is said to be a pair mean cordial labeling if for each edge uv of G, there exists a labeling ${\frac{{\lambda}(u)+{\lambda}(v)}{2}}$ if λ(u) + λ(v) is even and ${\frac{{\lambda}(u)+{\lambda}(v)+1}{2}}$ if λ(u) + λ(v) is odd such that ${\mid}{\bar{{\mathbb{S}}}}_{\lambda}{_1}-{\bar{{\mathbb{S}}}}_{{\lambda}^c_1}{\mid}{\leq}1$ where ${\bar{{\mathbb{S}}}}_{\lambda}{_1}$ and ${\bar{{\mathbb{S}}}}_{{\lambda}^c_1}$ respectively denote the number of edges labeled with 1 and the number of edges not labeled with 1. A graph G for which there exists a pair mean cordial labeling is called a pair mean cordial graph. In this paper, we investigate the pair mean cordial labeling behavior of few graphs including the closed helm graph, web graph, jewel graph, sunflower graph, flower graph, tadpole graph, dumbbell graph, umbrella graph, butterfly graph, jelly fish, triangular book graph, quadrilateral book graph.

• 전자공학회논문지A
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• 제32A권2호
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• pp.96-110
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• 1995

Traveling-wave electrodes for the high-speed Ti:LiNbO$_{3}$ modulators are designed. For a solution to the problems of 1) phase-velocity mismatching between the optical wave and the Modulating M/W, 2) M/W electrode characteristic impedance mismateching, we assume devices with 1$\mu$m thick SiO$_{2}$ buffer layer between the electrode and the Ti:LiNbO$_{3}$ substrate. The electrode analyses are performed by the FEM using the second-order triangular elements. The optimum design parameters to satisfy the phase-velocity matching and the characteristic impedance matching are sought for. By use of the analyses' results, a Mach-Zehnder optical modulator with a CPW electrode is designed as an example. the band-width estimation is also illustrated.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.568-572
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• 1998

This paper defines Fuzzy Logic Units(FLUs) which are piece wise finite elements in multidimension Euclidean space, and redefines triangular membership functions which are different from those defined in traditional literature. By analyzing FLUs, this paper gives a constructive method of fuzzy rules in fuzzy logic systems based on finite element method. The simulation results of single machine to infinite bus system show the effectiveness of the proposed method in this paper.