• 대한수학회보
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• 제52권4호
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• pp.1149-1167
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• 2015

We get a theorem which shows the existence of at least four $2{\pi}$-periodic weak solutions for the bifurcation problem of the Hamiltonian system with the superquadratic nonlinearity. We obtain this result by using the variational method, the critical point theory induced from the limit relative category theory.

• Korean Journal of Mathematics
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• 제25권3호
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• pp.455-468
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• 2017

We prove the existence of multiple solutions for the fourth order nonlinear elliptic problem with fully nonlinear term. Our method is based on the critical point theory; the variation of linking method and category theory.

• 한국가정과교육학회지
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• 제31권1호
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• pp.169-192
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• 2019

본 연구는 미래 사회에 대한 조망하는 관점을 비판적 시각에서 검토하고, 이러한 변화를 이끌어갈 수 있는 가정교육학의 방향을 비판과학 관점에서 탐색하는 데 목적을 두었다. 이를 위하여 Habermas의 비판이론에 대한 이해를 도모하고, 가정교육학이 비판이론에 기초한 비판과학 관점을 취했을 때 어떤 장에서 미래 사회를 이끌어 나갈 수 있는 실천을 하여야 하는지 그 방향성을 탐색하였다. 방향성은 개인, 가족과 사회가 상호호혜적이고 상호작용을 통하여 지속해가는 것을 비판이론에 기초하여 생활세계의 사적 영역, 생활세계의 공적 영역과 체계의 영역에서 탐색하였다. 비판과학 관점에서 가정교육학의 실천은 IFHE의 옹호활동과 정책참여 활동의 사례를 통해 발견되었다. 결론적으로 비판과학으로서의 가정교육학이 가정생활의 비판적, 참여적 변화를 가져올 수 있도록 생활세계에서 뿐만 아니라 사회·정치·경제체계를 바람직한 조건으로 형성해 나가고 학문적 영역, 일상생활의 영역, 사회적 영역에서 전문활동을 실천해나가야 할 당위성을 지지하였다.

• Advances in aircraft and spacecraft science
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• 제5권6호
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• pp.671-689
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• 2018

Bending, buckling and free vibration responses of functionally graded (FG) higher-order beams resting on two parameter (Winkler-Pasternak) elastic foundation are studied using a new inverse hyperbolic beam theory. The material properties of the beam are graded along the thickness direction according to the power-law distribution. In the present theory, the axial displacement accounts for an inverse hyperbolic distribution, and the transverse shear stress satisfies the traction-free boundary conditions on the top and bottom surfaces of the beams. Hamilton's principle is employed to derive the governing equations of motion. Navier type analytical solutions are obtained for the bending, bucking and vibration problems. Numerical results are obtained to investigate the effects of power-law index, length-to-thickness ratio and foundation parameter on the displacements, stresses, critical buckling loads and frequencies. Numerical results by using parabolic beam theory of Reddy and first-order beam theory of Timoshenko are specially generated for comparison of present results and found in excellent agreement with each other.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제12권4호
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• pp.239-247
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• 2008

Let $I{\in}C^{1,1}$ be a strongly indefinite functional defined on a Hilbert space H. We investigate the number of the critical points of I when I satisfies two pairs of Torus-Sphere variational linking inequalities and when I satisfies m ($m{\geq}2$) pairs of Torus-Sphere variational linking inequalities. We show that I has at least four critical points when I satisfies two pairs of Torus-Sphere variational linking inequality with $(P.S.)^*_c$ condition. Moreover we show that I has at least 2m critical points when I satisfies m ($m{\geq}2$) pairs of Torus-Sphere variational linking inequalities with $(P.S.)^*_c$ condition. We prove these results by Theorem 2.2 (Theorem 1.1 in [1]) and the critical point theory on the manifold with boundary.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1095-1099
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• 2008

Critical state theory involves two state boundary surface. One is Roscoe surface and the other is Hvorslev surface. The shape of these boundary surface was changed because of several parameters : Critical state constant(M), spacing ratio (r) and critical state pore pressure coefficient($\wedge$). As these constants make difference to each model and the way of solution, they may affect the shape of state boundary surface. Specially, spacing ratio (r) is important. On this study, triaxial compression test was performed using remolded weathered mudstone soil and investigated variation of state boundary surface because of spacing ratio. In the results of prediction, critical state point was located highly and the shape of boundary surface was changed more tightly curve as decreasing spacing ratio.

• 한국경영과학회지
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• 제29권1호
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• pp.1-16
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• 2004

Critical success factors (CSFs) have been replicated and applied in a wide variety of settings for more than two decades. Most previous research on CSF have focused on identifying critical factors, based on the variance theory, in terms of the correlation between individual factor and Information system (IS) success. However, it is unknown how a set of critical factors Influence each other and lead to IS success, which means the process of IS implementation. in this research, we aim to understand how a set of critical factors influence each other and lead to IS success in the context of IS implementation for Customer Relationship Management based on the process theory. This research has implications In explaining a mechanism leading to CRM systems success based on the influencial relationships among the critical factors.

• Korean Journal of Mathematics
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• 제16권4호
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• pp.527-535
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• 2008

Let $I{\in}C^{1,1}$ be a strongly indefinite functional defined on a Hilbert space H. We investigate the number of the critical points of I when I satisfies one pair of Torus-Sphere variational linking inequality. We show that I has at least two critical points when I satisfies one pair of Torus-Sphere variational linking inequality with $(P.S.)^*_c$ condition. We prove this result by use of the limit relative category and critical point theory on the manifold with boundary.

• Korean Journal of Mathematics
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• 제23권4호
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• pp.537-555
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• 2015

This paper is concerned with the existence of solutions to the following fractional differential inclusion $$\{-{\frac{d}{dx}}\(p_0D^{-{\beta}}_x(u^{\prime}(x)))+q_xD^{-{\beta}}_1(u^{\prime}(x))\){\in}{\partial}F_u(x,u),\;x{\in}(0,1),\\u(0)=u(1)=0,$$ where $_0D^{-{\beta}}_x$ and $_xD^{-{\beta}}_1$ are left and right Riemann-Liouville fractional integrals of order ${\beta}{\in}(0,1)$ respectively, 0 < p = 1 - q < 1 and $F:[0,1]{\times}{\mathbb{R}}{\rightarrow}{\mathbb{R}}$ is locally Lipschitz with respect to the second variable. Due to the general assumption on the constants p and q, the problem does not have a variational structure. Despite that, here we study it combining with an iterative technique and nonsmooth critical point theory, we obtain an existence result for the above problem under suitable assumptions. The result extends some corresponding results in the literatures.

• Structural Engineering and Mechanics
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• 제76권1호
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• pp.27-56
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• 2020

In this paper, the deflection and buckling analyses of porous nano-composite piezoelectric plate reinforced by carbon nanotube (CNT) are studied. The equations of equilibrium using energy method are derived from principle of minimum total potential energy. In the research, the non-local strain gradient theory is employed to consider size dependent effect for porous nanocomposite piezoelectric plate. The effects of material length scale parameter, Eringen's nonlocal parameter, porosity coefficient and aspect ratio on the deflection and critical buckling load are investigated. The results indicate that the effect of porosity coefficient on the increase of the deflection and critical buckling load is greatly higher than the other parameters effect, and size effect including nonlocal parameter and the material length scale parameter have a lower effect on the deflection increase with respect to the porosity coefficient, respectively and vice versa for critical buckling load. Porous nanocomposites are used in various engineering fields such as aerospace, medical industries and water refinery.