• 한국공간구조학회지
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• 제7권5호
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• pp.5-9
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• 2007

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.28-31
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• 1996

A bag is a set-like entity which can contain repeated elements. Fuzzy bags have been studied by Yager, who defined their basic relations and operations. However, his definitions of the basic relations and operations are inconsistent with the corresponding relations and operations for ordinary fuzzy sets. The present paper presents new basic relations and operations of fuzzy bags using a grade sequence for each element of the universal set. Moreover the .alpha.-cut, t-norms, the extension principle, and the composition of fuzzy bag relations are described.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 가을 학술발표회 논문집
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• pp.215-222
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• 1995

The objective of this paper is to develop a finite element structural analysis program using VB(Visual Basic) which has been recently getting popular as development tools of application program for Windows. VB provides several functions to develop an application program easily by supporting event-driven programming method and graphic object as control data type. This system is an integrated processor including preprocessor, solver and postprocessor. Automatic mesh generation is available at preprocess stage, and graphic presentation of deformation and stress is also represented at postprocess one.

• 한국군사과학기술학회지
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• 제9권4호
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• pp.137-144
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• 2006

단일요소 분사기(35kgf급)의 성능시험을 통해서 입증된 recess 2mm의 축소 모사된 로켓엔진(지상추력 250kgf급 다중요소 스월 동축형 분사기)을 설계, 해석, 제작, 시험하고, 이를 통하여 주요한 설계변수에 대한 검증과정을 수행하였다. 단일요소 및 다중요소 인젝터의 분무현상을 수치 해석적으로 모사하여 중첩에 의한 분무의 변화를 해석적으로 고찰하고 적용성 및 타당성을 확인하였다. 그리고 다중요소 분사기에 대한 연소성능시험을 통하여 엔진의 정상 연소성능을 평가하고 이를 단일요소 인젝터의 연소성능과 비교하여, 대형 로켓개발에 앞서 필요한 각 축소모델에 대한 특정 스케일에서의 다중요소 인젝터에 의한 연소성능을 평가하고 설계 자료를 확보, 합리적인 분사기 설계 변수자료를 확립하였다.

• 복합신소재구조학회 논문집
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• 제4권1호
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• pp.1-8
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• 2013

The finite element analysis (FEA) is a numerical technique to find solutions of field problems. A field problem is approximated by differential equations or integral expressions. In a finite element, the field quantity is allowed to have a simple spatial variation in terms of linear or polynomial functions. This paper represents a review and an accuracy-study of the finite element method comparing the FEA results with the exact solution. The exact solutions were calculated by solid mechanics and FEA using matrix stiffness method. For this study, simple bar and cantilever models were considered to evaluate four types of basic elements - constant strain triangle (CST), linear strain triangle (LST), bi-linear-rectangle(Q4),and quadratic-rectangle(Q8). The bar model was subjected to uniaxial loading whereas in case of the cantilever model moment loading was used. In the uniaxial loading case, all basic element results of the displacement and stress in x-direction agreed well with the exact solutions. In the moment loading case, the displacement in y-direction using LST and Q8 elements were acceptable compared to the exact solution, but CST and Q4 elements had to be improved by the mesh refinement.

• International Journal of Safety
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• 제2권1호
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• pp.39-44
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• 2003

The present study deals with an approximate integral equation approach to finite deflection of elastic plates with arbitrary plane form. An integral formulation leads to a system of boundary integral equations involving values of deflection, slope, bending moment and transverse shear force along the edge. The basic principles of the development of boundary element technique are reviewed. A computer program for solving for stresses and deflections in a isotropic, homogeneous, linear and elastic bending plate is developed. The fundamental solution of deflection and moment is employed in this program. The deflections and moments are assumed constant within the quadrilateral element. Numerical solutions for sample problems, obtained by the direct boundary element method, are presented and results are compared with known solutions.

• Advances in Computational Design
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• 제5권2호
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• pp.147-175
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• 2020

To achieve appropriate stresses, two new rectangular elements are presented in this study. For reaching this aim, a complementary energy functional is used within an element for the analysis of plane problems. In this energy form, the Airy stress function will be used as a functional variable. Besides, some basic analytical solutions are found for the stress functions. These trial functions are matched with each element number of degrees of freedom, which leads to a number of equations with the anonymous constants. Subsequently, according to the principle of minimum complementary energy, the unknown constants can be expressed in terms of displacements. This system can be rewritten in terms of the nodal displacement. In this way, two new hybrid-rectangular triangular elements are formulated, which have 16 and 40 degrees of freedom. To validate the outcomes, extensive numerical studies are performed. All findings clearly demonstrate accuracies of structural displacements, as well as, stresses.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.824-829
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• 2002

Since many reciprocating and rotating components are attached to jet loom structure. it is exposed to a more vibration and moise problems than the other textile machinery. Thus the design of the jet loom frame is very important to characterize the dynamic response. In this study, a finite element model of jet loom main frame was developed to investigate the dynamic characteristics of jet loom. Two different finite element models of different main frames were constructed and these models were validated by the experimental results. Dynamic characteristics such natural frequencies and mode shapes were in good agreement between the finite element analysis and experimental results within 10% error range. It is expected that the result from this study can be used as the basic information of jet loom dynamic analysis and be extended for further analysis of forced response case.

• 오토저널
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• 제10권6호
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• pp.54-60
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• 1988

During recent years, a great deal of interest has emerged on the use of adaptive approaches and a posteriori estimates in finite element method. The results are intended to be used to improve the quality of finite element solution by changing the location of the nodes within a fixed number of degrees of freedom-so called r method-, and by increasing the order of polynomial approximation with the new degrees of freedom-p method. This paper deals with error analysis that contains the basic theory and method of deriving error estimates and adaptive processes applied to finite element solutions underlying the rpm method that is the combination of r and p method of finite element. It is shown that we can obtain more accurate solution by applying the method to the 2-dimensional heat transfer problem.

• Structural Engineering and Mechanics
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• 제25권4호
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• pp.467-480
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• 2007

Two methods were developed for analyzing problems with two adjacent sub-domains modeled by different kinds of elements in finite element method. Each sub-domain can be defined independently without the consideration of equivalent division with common nodes used for the interface. These two methods employ an individual interface to accomplish the compatibility. The MLSA method uses the moving least square approximation which is the basic formulation for Element Free Galerkin Method to formulate the interface. The displacement field assumed by this method does not pass through nodes on the common boundary. Therefore, nodes can be chosen freely for this method. The results show that the MLSA method has better approximation than traditional methods.