• Structural Engineering and Mechanics
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• 제28권2호
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• pp.129-152
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• 2008

This paper considers the solution of the stochastic differential equations (SDEs) with random operator and/or random excitation using the spectral SFEM. The random system parameters (involved in the operator) and the random excitations are modeled as second order stochastic processes defined only by their means and covariance functions. All random fields dealt with in this paper are continuous and do not have known explicit forms dependent on the spatial dimension. This fact makes the usage of the finite element (FE) analysis be difficult. Relying on the spectral properties of the covariance function, the Karhunen-Loeve expansion is used to represent these processes to overcome this difficulty. Then, a spectral approximation for the stochastic response (solution) of the SDE is obtained based on the implementation of the concept of generalized inverse defined by the Neumann expansion. This leads to an explicit expression for the solution process as a multivariate polynomial functional of a set of uncorrelated random variables that enables us to compute the statistical moments of the solution vector. To check the validity of this method, two applications are introduced which are, randomly loaded simply supported reinforced concrete beam and reinforced concrete cantilever beam with random bending rigidity. Finally, a more general application, randomly loaded simply supported reinforced concrete beam with random bending rigidity, is presented to illustrate the method.

• East Asian mathematical journal
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• 제27권1호
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• pp.11-21
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• 2011

In this paper, we try to extend the viscosity approximation technique to find a particular common zero of a finite family of accretive mappings in a Banach space which is strictly convex reflexive and has a weakly sequentially continuous duality mapping. The explicit viscosity approximation scheme is proposed and its strong convergence to a solution of a variational inequality is proved.

• Industrial Engineering and Management Systems
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• 제4권2호
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• pp.123-128
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• 2005

The author derives a general explicit formula and presents an heuristic algorithm for solving Baker’s model. The examples show that this new approximate solution procedure for determining near optimum inspection intervals is more accurate than the ones suggested by Chung (1993) and Vaurio (1994), and is more efficient computationally than the one suggested by Hariga (1996). The construction and solution of the simplest profit model for an exponential failure distribution were presented in Baker (1990), and approximate analytical results were obtained by Chung (1993) and Vaurio (1994). The author will therefore mainly devote the following discussion to the problem of further approximating optimum inspection intervals.

• Structural Engineering and Mechanics
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• 제10권3호
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• pp.289-298
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• 2000

Based on the two-dimensional constitutive relationship of the piezoelastic material, this paper derived an analytic solution to the elastic beam with the piezoelectric layer under the electric field, presented the explicit expressions of its displacement and stress. It is helpful for understanding the electrical and mechanical behavior of piezoelectric materials as actuators and the validation of the numerical methods such as FEM.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.113-117
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• 1995

Viscous analysis on incompressible flows is performed using unstructured triangular meshes. A two-dimensional and axisymmetric incompressible Navier-Stokes equations are solved in time-marching form by artificial compressibility method. The governing equations are discretized by a cell-centered based finite-volume method. and a centered scheme is used for inviscid and viscous fluxes with fourth order artificial dissipation. An explicit multi-stage Runge-Kutta method is used for the time integration with local time stepping and implicit residual smoothing. Convergence properties are examined and solution accuracies are also validated with benchmark solution and experiment.

• Industrial Engineering and Management Systems
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• 제7권1호
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• pp.1-8
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• 2008

Having previously presented an article entitled "Further approximate optimum inspection intervals" in this Journal, here the author derives an alternative set of general explicit formulae using Cardan's solution to a cubic equation and presents a modified heuristic algorithm for solving Baker's model. The examples show that this new alternative approximate solution procedure for determining near optimum inspection intervals is as accurate and computationally efficient as the one suggested in the previous article. Through the examples, the author also indicates the relative merits and demerits of the two algorithms.

• 벤처창업연구
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• 제11권2호
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• pp.157-165
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• 2016

이 논문은 미시(微視)기반레벨에서 (at Micro-Foundations level) PBR(등급에 의한 가격책정)도구를 개발하여 PBR이 어느 상황에서든 가격책정(Pricing)의 기준과 비즈니스모델평가에 대한 일반적인 기준으로 사용될 수 있음을 주장하고 있다. 본 논문은 우선 구매력과 지불/구매의향 (Willingness to Pay/Purchase: WTP)을 동시에 지니고 있는 현시니즈(Explicit Needs)로부터 WTP모델을 유도하여 WTP수준과 WTS(willingness to supply/sell: 공급/판매의향) 수준간의 간격에 대한 서열척도(ordinal scale)를 취하여 PBR방법을 개발하였다. 구체적으로 고객이 기대하는 이상적 마케팅믹스인 최선의 SPEC (Solution, Price Indicator by WTP, Encouragement, Channel)과 기업이 제공하는 실제 마케팅믹스 (Marketing Mix) 4P에 대하여 우선 각 구성요소 마다마다를 상호 개별적으로 비교할 뿐만 아니라 전체를 하나로 인식하여 상호 비교함으로써 PBR방법을 개발한 후 이를 적용한 몇 가지 예시를 통해서 PBR방법이 실제로 비즈니스모델을 평가하는데 사용될 수 있음을 보여 준다. 결론적으로 본 논문은 어떤 상황에서든 PBR이 가격책정과 비즈니스모델의 평가도구로서 유용하게 사용될 수 있다고 주장한다.

• 한국컴퓨터그래픽스학회논문지
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• 제23권1호
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• pp.39-48
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• 2017

본 논문에서는 3차원상의 두 강체 사이의 침투깊이 (penetration depth)를 명시적으로 민코우스키 합 (explicit Minkowski sum)을 생성하는 방법 ($PD_e$)과 암시적으로 민코우스키 합 (implicit Minkowski sum)을 생성 하는 방법 ($PD_i$)을 이용하여 계산하는 알고리즘을 제안하고 이들의 성능을 비교한다. 3차원 강체들 간의 침투깊이를 구하는데 성능상에 큰 장애가 되는 것이 민코우스키 합의 생성이다. 본 논문의 알고리즘들은 우선 물체의 중심 차 (centroid difference)와 운동 일관성 (motion coherence)기법을 이용하여 침투깊이를 예측한다. 특히 $PD_e$는 추측된 침투깊이에 부분 민코우스키 합을 명시적으로 생성 혹은 갱신하여 침투깊이를 빠르게 구한다. 반면에 $PD_i$는 민코우스키 합을 명시적으로 생성하기보다는 민코우스키 합에 접하는 접평면만을 반복적으로 생성하여 국소적으로 최적화된 침투깊이를 계산한다. 본 연구의 알고리즘들을 수천 개의 삼각형으로 이루어진 강체를 이용해 실험한 결과 수 밀리초 (millisecond) 이내의 빠른 속도로 침투깊이를 계산할 수 있다는 것을 실험적으로 보인다.

• Computers and Concrete
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• 제25권1호
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• pp.67-73
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• 2020

Traditionally used analytical approach to predict the fatigue failure of reinforced concrete (RC) structure is generally conservative and has certain limitations. The nonlinear finite element method (FEM) offers less expensive solution for fatigue analysis with sufficient accuracy. However, the conventional implicit dynamic analysis is very expensive for high level computation. Whereas, an explicit dynamic analysis approach offers a computationally operative modelling to predict true responses of a structural element under periodic loading and might be perfectly matched to accomplish long life fatigue computations. Hence, this study simulates the fatigue behaviour of RC beams with finite element (FE) assemblage presenting a simplified explicit dynamic numerical solution to show computer aided fatigue behaviour of RC beam. A commercial FEM package, ABAQUS has been chosen for this complex modelling. The concrete has been modelled as a 8-node solid element providing competent compression hardening and tension stiffening. The steel reinforcements are simulated as two-node truss elements comprising elasto-plastic stress-strain behaviour. All the possible nonlinearities are duly incorporated. Time domain analysis has been adopted through an automatic Newmark-β time incremental technique. The program consists of twelve RC beams to visualize the real behaviour during fatigue process and to obtain the reliability of the study. Both the numerical and experimental results indicate a redistribution of stresses along the time and damage accumulation of beam which severely affect the serviceability and ultimate capacity of RC beam. The output of the FEM analysis demonstrates good match with the experimental consequences which affirm the efficacy of the computer aided model. The controlled fatigue damage evolution at service fatigue load limits makes the FE model an efficient tool in predicting high cycle fatigue behaviour of RC structures.

• 논리연구
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• 제16권1호
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• pp.17-43
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• 2013

최근에 이병욱 교수는 집단인과개념을 이용함으로써 선행결과역설에 대한 새로운 해결방식을 제시하고자 했다. 이 논문에서 필자는 이병욱 교수의 해결방식이 우리 인과개념에 대한 지평을 확장시켜 주는 기여를 하지만 선행결과역설에 대한 만족스런 해결이 되지 못함을 보이고자 한다. 필자는 우선 선행결과역설에 우리가 직면하고 있는 수수께끼의 두 가지 원천을 밝히고, 이 역설을 해결하기 위해 반드시 만족시켜야 할 두 가지 조건을 제시할 것이다. 그리고 이병욱 교수의 해결방식은 그 두 가지 조건을 동시에 충족시킬 수 없음을 논증할 것이다.