• Structural Engineering and Mechanics
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• 제17권6호
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• pp.789-817
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• 2004

This paper deals with the modal analysis of rotational shell structures by means of the numerical solution technique known as the Generalized Differential Quadrature (G. D. Q.) method. The treatment is conducted within the Reissner first order shear deformation theory (F. S. D. T.) for linearly elastic isotropic shells. Starting from a non-linear formulation, the compatibility equations via Principle of Virtual Works are obtained, for the general shell structure, given the internal equilibrium equations in terms of stress resultants and couples. These equations are subsequently linearized and specialized for the rotational geometry, expanding all problem variables in a partial Fourier series, with respect to the longitudinal coordinate. The procedure leads to the fundamental system of dynamic equilibrium equations in terms of the reference surface kinematic harmonic components. Finally, a one-dimensional problem, by means of a set of five ordinary differential equations, in which the only spatial coordinate appearing is the one along meridians, is obtained. This can be conveniently solved using an appropriate G. D. Q. method in meridional direction, yielding accurate results with an extremely low computational cost and not using the so-called "delta-point" technique.

• Interaction and multiscale mechanics
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• 제5권4호
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• pp.317-345
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• 2012

Cable-stayed bridges are often used in modern bridge engineering for connecting two geographical points of long distance. A special load case to cable-stayed bridges is earthquake, which can produce horizontal as well as vertical movements on the pylons of the bridge. These movements may be transient in nature, i.e., only resulting in the transient vibration of the bridge, but causing no damage consequences. In some extreme cases, they may cause permanent subsidence on one or more pylons of the bridge. In this paper, the effect of pylons' subsidence on the dynamic deformations of the bridge and on the cables' strength is thoroughly studied. Conclusions useful to the design of cable-stayed bridges will be drawn from the numerical study.

• 성인간호학회지
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• 제15권4호
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• pp.639-649
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• 2003

Purpose: The purpose of this study was to identify the effect of dynamic imagery therapy on "anger-in" and immune function in patients with breast cancer. Method: Dynamic imagery therapy was given for 10 sessions with 2 times informative education. Data collection was from June, 24th to August, 12th 2002. The participants were experimental group 15, control group 15. This study was designed using a quasi-experimental approach with non-equivalent Pre test-Post test Design. The instruments used in this study include the anger scale developed by Spielberger(1972) and modified by Chon, Kyum Koo (1996), The data was analysed with $\chi^2$-test, t-test, ANOVA and ANCOVA. Result: 1) That the level of "Anger-in" in patients will be significantly lower than that of the control group was supported (p<.001). 2) That the level of T3 lymphocyte and NK Cells, IgG. Cortisol in patients will be significantly lower than that of the control group was supported (T3, IgG: p<.05, Cortisol p<.001). Conclusion: The dynamic imagery therapy is suggested as an effective nursing intervention to reduce anger level and increase immune function for patients with breast cancer.

• 대한수학회지
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• 제47권4호
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• pp.659-674
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• 2010

This paper is concerned with the asymptotic behavior of solutions of the second-order nonlinear perturbed dynamic equation $$(r(t)x^{\Delta}(t))^{\Delta}\;+\;F(t,\;x^{\sigma}))=G(t,\;x^{\sigma},\;(x^{\Delta})^{\sigma})$$ on a time scale $\mathbb{T}$. By using a new technique we establish some sufficient conditions which ensure that every solution oscillates or converges to zero. Our results improve the known oscillation results on the literature for the perturbed dynamic equations on time scales. Some examples illustrating our main results are given.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.201-202
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• 2007

• Computers and Concrete
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• 제20권2호
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• pp.229-246
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• 2017

The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

• 한국지반공학회논문집
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• 제32권3호
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• pp.39-47
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• 2016

본 연구에서는 말뚝 설치 방법에 따른 동적 p-y 곡선의 차이를 분석하기 위하여, 1g 상태에서 지반 조성 전 설치한 말뚝과 지반 조성이 완료된 후에 1g 상태에서 압입하여 설치한 말뚝, 그리고 40g의 원심 가속도 조건에서 압입시킨 말뚝에 대해 동적 원심모형 실험을 수행하였다. 실험 결과로부터 얻은 각 모형 말뚝의 동적 p-y 곡선의 최대지반반력을 이용하여 동적 p-y 중추곡선(Backbone curve)을 쌍곡선 함수로 나타내었다. 말뚝 설치 방법에 따른 동적 p-y 중추곡선 분석 결과, 40g 조건에서 압입한 말뚝이 1g 상태에서 압입한 말뚝 및 지반 조성 전 설치 말뚝에 비해 말뚝에 작용하는 지반반력이 크게 평가되었으며, 이러한 지반반력의 차이는 깊이가 깊어질수록 작아지는 것으로 나타났다. 일련의 p-y 곡선 결과를 바탕으로 기존에 제안된 현장타설말뚝에 대한 동적 p-y 중추곡선의 적용성을 평가하고, 이를 수정한 압입 및 항타 말뚝에 대한 동적 p-y 곡선 산정식을 개발하였다.

• Journal of applied mathematics & informatics
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• 제30권1_2호
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• pp.289-304
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• 2012

In this paper, we study asymptotic behaviour of solutions of the following higher order nonlinear dynamic equations $$S_n^{\Delta}(t,x)+{\delta}p(t)f(x(g(t)))=0$$ and $$S_n^{\Delta}(t,x)+{\delta}p(t)f(x(h(t)))=0$$ on an arbitrary time scale $\mathbb{T}$ with sup $\mathbb{T}={\infty}$, where n is a positive integer, ${\delta}=1$ or -1 and $$S_k(t,x)=\{\array x(t),\;if\;k=0,\\a_k(t)S_{{\kappa}-1}^{\Delta}(t),\;if\;1{\leq}k{\leq}n-1,\\a_n(t)[S_{{\kappa}-1}^{\Delta}(t)]^{\alpha},\;if\;k=n,$$ with ${\alpha}$ being a quotient of two odd positive integers and every $a_k$ ($1{\leq}k{\leq}n$) being positive rd-continuous function. We obtain some sufficient conditions for the equivalence of the oscillation of the above equations.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 학술발표집 지반진동 영향평가
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• pp.83-116
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• 1993

본 고는 쓰레기 매립장에서 동다짐을 시행할 시 발생하는 진동을 측정하고, 그 결과를 분석하여 쓰레기 매립지반의 동다짐 진동 특성을 고찰하였다. 진동특성은 크게 쓰레기 매립지반의 일반적 진동특성과 동다짐 조건 변화에 의한 진동특성의 2가지 측면으로 검토되었다. 그 결과 연구대상 쓰레기 매립지반의 기본적인 진동특성으로 충격지점 주위에서의 전단계수 G 행 17496~58320 t/m2, 감쇠비 D=14~58%, 탁월진동수 f=6~14 Hz 등으로 나타났다. 동다짐 조건 차이에 의한 진동특성으로는 타격회수가 증가될수록 cross hole시험에 의한 전단파 및 압축파의 속도가 중가하였으며, 타격지점으로 부터의 거리와 최대입자속도는 vPP = 5.08 [D/E]-1.4의 관계를 가지며, 쓰레기층 바닥에서는 반사파의 영향으로 진동의 진폭이 커지는 것으로 나타났다. 또한 진동에 의하여 지반이 개량되는 범위는 타격지점으로 부터 반경 약 6~10 m정도인 것으로 나타났다.

• Interaction and multiscale mechanics
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• 제3권1호
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• pp.39-54
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• 2010

In this paper, a simple approach is presented for studying the dynamic response of multi-span steel bridges supported by pylons of different heights, subjected to earthquake motions acting along the axis of the bridge with spatial variations. The analysis is carried out using the modal analysis technique, while the solution of the integral-differential equations derived is obtained using the successive approximations technique. It was found that the height of piers and the quality of the foundation soil can affect significantly the dynamical behavior of the bridges studied. Illustrative examples are presented to highlight the points of concern and useful conclusions are gathered.