• 한국지반신소재학회논문집
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• 제20권3호
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• pp.11-20
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• 2021

본 논문에서는 유한요소법과 경계요소법을 결합하여 기하학적으로 급변 부위가 있는 이차원 탄성 정적 문제에 대하여 효율적이고 정확한 해석 결과를 얻기 위한 유한요소법과 경계요소법의 근사 결합 방법을 제시한다. 이차원 문제의 유한요소로서는 3절점, 4절점 평면응력 요소를 적용하고, 이차원 문제의 경계요소로는 3절점 경계요소를 적용한다. 모델링 단계에서는 우선 전체 해석 대상을 유한요소로 모델링한 후에 기학학적 급변 부위를 경계요소로 모델링 하는데, 유한요소의 모델링을 위하여 정의된 절점을 이용하여 경계요소를 정의한다. 해석 단계에서는 전체 해석 대상에 대하여 유한요소 해석을 우선적으로 수행하고, 이후에 경계요소 해석을 자동으로 수행하는데, 경계부에서의 경계조건은 유한요소 해석 결과인 변위 조건과 응력 조건을 적용한다. 수치예제로서 이차원 탄성 정적 문제인 균열이 있는 평판에 대한 해석 결과를 제시하고 고찰한다.

• 말소리와 음성과학
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• 제8권1호
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• pp.53-62
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• 2016

In this study, we examined whether Chinese learners of Korean can correctly produce the phonological process on the lexical and post-lexical level. For this purpose 4 Korean native speakers and 10 advanced and 10 intermediate Chinese learners of Korean participated in the production test. The materials analyzed constituted 10 Korean sentences in which nasalization can be applied on the syllable boundary, word boundary(w-boundary) as well as accentual phrase boundary(AP-boundary). The results show that for Korean speakers, nasalization was applied 100% at all level whereas for Chinese speakers, the rate of application of nasalization is different according to prosodic constituents and Korean proficiency. Nasalization was more frequently applied at the lexical level than the post-lexical level, and it is more frequent in the w-boundary conditions than in the AP-boundary conditions. However, the rate of nasalization in the w-boundary is close to the lexical level. The pronunciation errors were committed either as non application of nasalization or coda obstruent ommission. In the case of non application of nasalization, Chinese learners of Korean produced the target syllables as underling forms, which were not transformed as surface forms. In addition, we can observe the ommission of coda obstruents in 'lenis obstruents+nasal sound' sequences. As a result, nasalization is blocked by this omission.

• 대한수학회지
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• 제43권4호
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• pp.733-763
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• 2006

We study quasi-stationary Stokes flow in a dihedral domain arising from a study of a free boundary problem of viscous fluid in a container. We construct an exact solution of quasi-stationary Stokes equations and derive its estimates with norm in a weighted Sobolev spaces.

• 대한수학회지
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• 제40권4호
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• pp.681-693
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• 2003

In this paper, we first prove that there are no automorphism orbits accumulating at a boundary point of the largest isolated finite type. We also present a generalization of the results of Isaev and Krantz on the structure of the orbit accumulation points.

• 한국구조물진단유지관리공학회 논문집
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• 제24권5호
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• pp.77-85
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• 2020

본 연구에서는 2주탑 콘크리트 사장교를 대상으로 경계조건에 따른 지진 취약도 곡선을 작성하고, 경계조건이 교량의 지진 취약도에 미치는 영향을 평가하고자 한다. 대상교량에 대한 해석모델이 Midas Civil을 사용하여 구축되었고 Fiber요소와 콘크리트, 철근의 재료모델을 적용하여 비선형 시간이력해석을 수행하였다. 주탑과 보강형 사이의 경계조건을 강결, 비구속, 포트받침, 면진받침의 총 4가지로 구분하여 각각의 경계조건에 대해 지진 취약도 곡선을 작성하였다. 주탑의 소성힌지구간과 연결부, 케이블을 취약부재로 선정하고 이 부재들에 대해 지진 취약도 곡선을 작성하였다. 분석결과 주탑의 소성힌지구간과 연결부에서는 면진받침모델이 가장 낮은 손상확률을 나타내고, 케이블의 지진 취약도는 경계조건에 의한 영향이 다른 부재에 비해 크지 않은 것을 알 수 있다.

• Coupled systems mechanics
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• 제4권1호
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• pp.1-18
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• 2015

The state-based peridynamics is considered a nonlocal method in which the equations of motion utilize integral form as opposed to the partial differential equations in the classical continuum mechanics. As a result, the enforcement of boundary conditions in solid mechanics analyses cannot follow the standard way as in a classical continuum theory. In this paper, a new approach for the boundary condition enforcement in the state-based peridynamic formulation is presented. The new method is first formulated based on a convex kernel approximation to restore the Kronecker-delta property on the boundary in 1-D case. The convex kernel approximation is further localized near the boundary to meet the condition that recovers the correct boundary particle forces. The new formulation is extended to the two-dimensional problem and is shown to reserve the conservation of linear momentum and angular momentum. Three numerical benchmarks are provided to demonstrate the effectiveness and accuracy of the proposed approach.

• Journal of applied mathematics & informatics
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• 제40권3_4호
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• pp.675-694
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• 2022

In this article, we investigate the solution of the inverse problem for one dimensional heat equation with Neumann and Robin boundary conditions, that is, we determine the temperature and source term with given initial and boundary conditions. Three radial basis functions(RBFs) have been used for numerical solution, and Homotopy perturbation method for analytic solution. Numerical solutions which are obtained by considering each of the three RBFs are compared to the exact solution. For appropriate value of shape parameter c, numerical solutions best approximates exact solutions. Furthermore, we have shown the impact of noisy data on the numerical solution of u and f.

• Advances in materials Research
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• 제5권4호
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• pp.279-298
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• 2016

Present disquisition proposes an analytical solution method for exploring the buckling characteristics of porous magneto-electro-elastic functionally graded (MEE-FG) plates with various boundary conditions for the first time. Magneto electro mechanical properties of FGM plate are supposed to change through the thickness direction of plate. The rule of power-law is modified to consider influence of porosity according to two types of distribution namely even and uneven. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM plate under magneto-electrical field via Hamilton's principle. An analytical solution procedure is exploited to achieve the non-dimensional buckling load of porous FG plate exposed to magneto-electrical field with various boundary condition. A parametric study is led to assess the efficacy of material graduation exponent, coefficient of porosity, porosity distribution, magnetic potential, electric voltage, boundary conditions, aspect ratio and side-to-thickness ratio on the non-dimensional buckling load of the plate made of magneto electro elastic FG materials with porosities. It is concluded that these parameters play remarkable roles on the dynamic behavior of porous MEE-FG plates. The results for simpler states are confirmed with known data in the literature. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

• Kyungpook Mathematical Journal
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• 제48권4호
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• pp.637-650
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• 2008

New sufficient conditions for the existence of at least one solution of Neumann type boundary value problems for second order nonlinear differential equations $$\array{\{{p(t)\phi(x'(t)))'=f(t,x(t),\;x(\tau_1(t)),\;{\cdots},\;x(\tau_m(t))),\;t\in[0,T],\\x'(0)=0,\;x'(T)=0,}\,}$$, are established.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.763-774
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• 2014

A simple and efficient vibration analysis procedure for stiffened panels with openings and arbitrary boundary conditions based on the assumed mode method is presented. Natural frequencies and modes are determined by solving an eigenvalue problem of a multi-degree-of-freedom system matrix equation derived by using Lagrange's equations of motion, where Mindlin theory is applied for plate and Timoshenko beam theory for stiffeners. The effect of stiffeners on vibration response is taken into account by adding their strain and kinetic energies to the corresponding plate energies whereas the strain and kinetic energies of openings are subtracted from the plate energies. Different stiffened panels with various opening shapes and dispositions for several combinations of boundary conditions are analyzed and the results show good agreement with those obtained by the finite element analysis. Hence, the proposed procedure is especially appropriate for use in the preliminary design stage of stiffened panels with openings.