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전처리된 켤레구배법의 전체-국부 확장함수를 지닌 일반유한요소해석에의 응용
최원정,김민숙,김대진,이영학,김희철,Choi, Won-Jeong,Kim, Min-Sook,Kim, Dae-Jin,Lee, Young-Hak,Kim, Hee-Cheul 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.4
This paper introduces the generalized finite element method with global-local enrichment functions using the preconditioned conjugate gradient method. The proposed methodology is able to generate enrichment functions for problems where limited a-priori knowledge on the solution is available and to utilize a preconditioner and initial guess of good quality with only small addition of computational cost. Thus, it is very effective to analyze problems where a complex behavior is locally exhibited. Several numerical experiments are performed to confirm its effectiveness and show that it is computationally more efficient than the analysis utilizing direct solvers such as Gauss elimination method. 본 논문에서는 켤레구배법을 이용해 전체-국부 확장함수를 지닌 일반유한요소법을 해석하는 방식을 제안한다. 이 기법은 편미분방정식의 해에 대한 정보가 충분하지 않은 경우에도 수치해석적인 방법으로 일반유한요소법의 확장함수를 구성할 수 있으며, 해석과정 중 약간의 추가적인 연산만으로 좋은 성능을 지닌 전처리행렬 및 초기 추측치를 구성할 수 있어 국부적으로 복잡한 거동을 보이는 문제의 해석에 효과적이다. 본 논문에 포함된 수치해석 예제의 결과는 제안된 기법이 가우스 소거법과 같은 직접 솔버를 이용하는 경우보다 수치해석적으로 더 효율적임을 보여준다.
박준,박현일,이승래,지성현 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.6
In this paper, a method is presented for estimating the bearing capacity of shallow foundations based on the Discrete Element Method (DEM). By applying Winkler-springs for accounting for the compatibility between soil blocks, the proposed method can estimate the state of stress at failure surface and the ultimate bearing capacity. For the investigation of the application of the method, example problems about shallow foundations on the single layer and two layers soil are analyzed.
장윤석,석창성,김영진 대한기계학회 1995 대한기계학회논문집 Vol.19 No.4
In order perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain (.sigma. - .epsilon.) curves and fracture resistance (J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. The objective of this paper is to develop two methods for J-R curve prediction. In the first method, elastic-plastic finite element analyses for a series of crack length / specimen width ratio were performed. Accordingly the load versus load line displacement (P .delta.) curve corresponding to the fracture strain is obtained and the J-R curve based on the generalized locus method is obtained. In the second method, the correlation between .sigma.-.epsilon. curves and J-R curves was statistically analyzed and an empirical equation to predict the J-R curve from the .sigma.-.epsilon. test result is proposed. A good correlation between the predicted results based on the proposed methods and the experimental ones is obtained.
안형택(Hyung Taek),이은택(Euntaek Lee) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
Variational multiscale method (VMS) is a new framework of stabilized finite element method that can be applied to the various regimes of fluid flow problems, namely laminar or turbulent flows, without any a prior knowledge of flow field. It is also based on the scale separation, for fully resolved and unresolved sub-grid scales which is being used in large-eddy simulation of turbulent flows. In this paper the VMS technique is applied to the free-surface flows. In order to simulate two phase flow of air-water mixture, the governing equation is expressed in dimensional form, and the VMS formulation is presented for the air-water mixture. Fully-filled and half-filled water tank is calculated under hydrostatic condition in order to check the validity of the current formulation. Dam-break problem with an obstacle is to be tested for the validity of the current approach.