• Journal of Information Processing Systems
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• 제14권5호
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• pp.1068-1074
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• 2018

In this paper, we consider the delay partial differential equation of three dimensions with constant coefficients. We established the alternating direction difference scheme by the standard finite difference method, gave the order of convergence of the format and the expression of the difference scheme truncation errors.

• Steel and Composite Structures
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• 제39권1호
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• pp.109-123
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• 2021

This research endeavor intends to use the implicit finite element method to investigate the structural response of steel shear walls with partial plate-column connection. To this end, comprehensive verification studies are initially performed by comparing the numerical predictions with several reported experimental results in order to demonstrate the reliability and accuracy of the implicit analysis method. Comparison is made between the hysteresis curves, failure modes, and base shear capacities predicted numerically using ABAQUS software and obtained/observed experimentally. Following the validation of the finite element analysis approach, the effects of partial plate-column connection on the strength and stiffness performances of steel shear wall systems with different web-plate slenderness and aspect ratios under monotonic loading are investigated through a parametric study. While removal of the connection between the web-plate and columns can be beneficial by decreasing the overall system demand on the vertical boundary members, based on the results and findings of this study such detachment can lower the stiffness and strength capacities of steel shear walls by about 25%, on average.

• 한국항공우주학회지
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• 제38권12호
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• pp.1153-1161
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• 2010

본 연구에서는 주기적 비정상 유동 해석을 위해 푸리에 변환을 이용하는 조화 균형법의 효율적인 해법을 제안한다. 내재적으로 유속항을 처리하고 외재적으로 조화 원천항을 처리하였다. 외재적 조화 균형법 보다 더 빠르게 수렴 시킬 수 있으며 내재적 조화 균형법을 적용할 때 추가되는 자코비안 행렬을 처리할 필요가 없다. 또한 완전 내재적 기법에 상응하는 수준의 수렴안정성을 확인할 수 있었다. 2차원 비정상 유동 문제로 피칭하는 NACA0012 익형에 적용하였으며 이중 시간 적분법 및 외재적 Runge-Kutta기법의 해와 매우 일치하는 결과를 얻었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.219-230
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• 1999

The Equations of Chemical kinetics are very stiff, which forces the use of an implicit scheme. The problem of implicit scheme, however, is that the jacobian must be solved at each time step. In this paper, we examined the methodology that can be stable without full chemical jacobian, This method is derived by applying the different time steps to the chemical source term. And the lower triangular chemical jacobian is derived. This is called the preconditioned time differencing method and represents partial implicit method. We show that this method is more stable in chemical kinetics than the full implicit method and that this is more efficient in supersonic combustion problem than the full jacobian method with same accuracy.

• 한국연소학회지
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• 제13권1호
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• pp.17-22
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• 2008

A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.

• 호남수학학술지
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• 제37권4호
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• pp.441-455
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• 2015

In this paper, we perform a comparison study of explicit and implicit numerical methods for the equity-linked securities (ELS). The option prices of the two-asset ELS are typically computed using an implicit finite diffrence method because an explicit finite diffrence scheme has a restriction for time steps. Nowadays, the three-asset ELS is getting popularity in the real world financial market. In practical applications of the finite diffrence methods in computational finance, we typically use relatively large space steps and small time steps. Therefore, we can use an accurate and effient explicit finite diffrence method because the implementation is simple and the computation is fast. The computational results demonstrate that if we use a large space step, then the explicit scheme is better than the implicit one. On the other hand, if the space step size is small, then the implicit scheme is more effient than the explicit one.

• 대한수학회논문집
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• 제11권2호
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• pp.495-501
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• 1996

There is currently a regain of interest in ADI (Alternating Direction Implicit) method as a preconditioner for iterative Method for solving large sparse linear systems, because of its suitability for parallel computation. However the classical ADI is not applicable to FE(Finite Element) matrices. In this paper wer propose a Block-ADI method, which is applicable to Finite Element metrices. The new approach is a combination of classical ADI method and domain decompositi on. Also, we provide a partial proof of the convergence based on the results from the regular splittings, in case the discretization metrix is symmetric positive definite.

• 한국정보통신학회논문지
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• 제8권3호
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• pp.702-707
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• 2004

본 논문은 CCD 카메라와 거리 센서를 사용하여 컨테이너의 자세 측정에 관하여 연구하였다. 특히 특징점을 추출하고 영상의 잡음을 줄이는 방법에 대하여 중점적으로 기술하였다. 가우시안 및 랜덤 노이즈를 제거하기 위하여 Euler-Lagrange 방정식을 소개하였으며 PDE(Partial Differential Equation)를 기초로 한 Euler-Lagrange 방정식을 풀기 위하여 ADI(Alternating Direction Implicit)방법을 적용하였다. 그리고 스프레더와 컨테이너의 특징점을 추출하기 위해서 기존의 황금 분할법과 이분 분할법을 이용한 방법은 지역적 최대 및 최소 값의 경우 정확한 해를 구할 수 없어서 k차 곡률 알고리즘을 이용하였다. 제안된 알고리즘은 영상의 전처리과정에서 잡음제거에 효과적이며 카메라와 거리센서를 이용한 제안 시스템은 기존시스템의 구조적 변경 없이 사용가능하기 때문에 비용이 저렴한 장점이 있다.

• 한국항공우주학회지
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• 제31권7호
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• pp.1-8
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• 2003

본 논문은 극초음속 유동과 공력가열 해석에서 나타나는 공기 반응의 수치해석적 특징을 다루고 공기반응을 효율적으로 해석하는 부분 내재적 적분법을 공기반응에 적용하였다. 안정적 계산을 위해 화학반응 자코비안이 필수적임을 밝혔으며 자코비안의 양의 실수 특성치로 인한 수치기법의 경직성은 일반적인 연소반응에 비하여 미약하였다. 공기반응에서 부분 내재적 적분법은 화학종 순서의 종속성이 없었으며 완전 내재적 적분법과 동일한 수렴율과 계산 결과를 보였다. 극초음속 유동해석에 부분 내재적 적분법을 적용하면 전체 연산 시간이 감소되었다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제25권4호
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• pp.173-195
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• 2021

A new implicit discontinuous Galerkin spectral element method (DGSEM) based on the first order hyperbolic system(FOHS) is presented for solving elliptic type partial different equations, such as the Poisson problems. By utilizing the idea of hyperbolic formulation of Nishikawa[1], the original Poisson equation was reformulated in the first-order hyperbolic system. Such hyperbolic system is solved implicitly by the collocation type DGSEM. The steady state solution in pseudo-time, which is the solution of the original Poisson problem, was obtained by the implicit solution of the global linear system. The optimal polynomial orders of 𝒪(𝒽^𝑝+1)) are obtained for both the solution and gradient variables from the test cases in 1D and 2D regular grids. Spectral accuracy of the solution and gradient variables are confirmed from all test cases of using the uniform grids in 2D.