• 한국농공학회지
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• 제34권4호
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• pp.97-105
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• 1992

The main purpose of this paper is to present the buckling loads of tapered columns due to dynamic concept. The ordinary differential equation governing the bucking loads for tapered columns is derived on the basis of dynamic concept. Three kinds of cross sectional shape are considered in the governing equation. The Improved Euler method and Determinant Search method are used to perform the integration of the differential equation and to determine the buckling loads, respectively. The hinged-hinged, hinged-clamped, clamped-clamped and free-clamped end constraints are applied in numerical examples. The buckling loads are reported as the function of section ratio, and the effects of cross-sectional shapes are investigated. The buckling load equation, which are fitted by numerical data, are proposed as a function of section ratio. It is expected that these equations can be utilized in structural engineering field.

• 컴퓨터교육학회논문지
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• 제21권5호
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• pp.1-10
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• 2018

2015 개정교육과정에 따라 개정된 정보 교과는 2018년부터 중학교 학생들에게 필수 교과로 도입되었다. 정보 교육과정에 나타난 추상화의 개념은 일반적인 추상화와 공통점과 차이점이 있는데, 현재 정보 교과서에는 이런 개념이 혼재되어 있다. 컴퓨팅 사고력의 추상화는 자동화와의 연결이 반드시 필요하며, 지금처럼 혼재된 사례로는 제대로 된 추상화 개념을 가르치기 어렵다. 따라서, 본 연구에서는 개정 교육과정에 따라 개발된 정보 교과서를 조사하여 추상화의 개념과 예시내용을 분석하였다. 분석결과 여러 정보 교과서의 추상화 내용이 자동화와 연결되지 않고 있으며, 일반적인 추상화의 개념과 혼재되어 사용되고 있었다. 이를 개선하기 위해 컴퓨팅 사고력 증진을 위한 명확한 추상화의 개념과 교육활동을 예시로 제시하였다. 본 연구의 결과는 컴퓨팅 사고력을 증진하기 위한 추상화 수업 재구성의 기초자료로 활용할 수 있다.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.933-945
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• 2004

In this paper, S (stochastic)-eigenvalue concept and its S-eigenvector for linear continuous-time systems with probabilistic uncertainties is proposed. The proposed concept is concerned with the perturbation of eigenvalues due to the probabilistic variable parameters in the dynamic model of a plant. S-eigenstructure assignment scheme via the Sylvester equation approach based on the S-eigenvalue concept is also proposed. The proposed design schemes are illustrated by numerical examples, and applied to the longitudinal dynamics of open-loop-unstable aircraft with possible uncertainties in aerodynamic and thrust effects as well as separate dynamic pressure. These results explicitly characterize how S-eigenvalues in the complex plane may impose stability on S-eigenstructure assignment.

• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.145-156
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• 1996

Although knowledge discovery is increasingly important in databases, the discovered knowledge sets may not be effectively used for application domains. It is partly because knowledge discovery does not take user's interests into account, and too many knowledge sets are discovered to handle efficiently. We believe that user's interests are conveyed by a query and if a nested query is concerned it may include a user's thought process. This paper describes a novel concept for discovering knowledge sets based on query processing. Knowledge discovery process is performed by: extracting features from databases, spanning features to generate range features, and constituting a knowledge set. The contributions of this paper include the following: (1) not only simple queries but also nested queries are considered to discover knowledge sets regarding user's interests and user's thought process, (2) not only positive examples (answer to a query) but also negative examples are considered to discover knowledge sets regarding database abstraction and database exceptions, and (3) finally, the discovered knowledge sets are quantified.

• Journal of Theoretical and Applied Mechanics
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• 제2권1호
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• pp.31-50
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• 1996

In this paper, a finite element analysis based on the local approach concept to fracture in the continuum damage mechanics is performed to analyze ductile fracture in two dimensional quasi-static state. First an isotropic damage model based on the generalized concept of effective stress is proposed for structural materials in the context of large deformation. In this model, the stiffness degradation is taken as a measure of damage and so, the fracture phenomenon can be explained as the critical deterioration of stiffness at a material point. The modified Riks' continuation technique is used to solve incremental iterative equations. Crack propagation is achieved by removing critically damaged elements. The mesh size sensitivity analysis and the simulation of the well known shearing mode failure in plane strain state are carried out to verify the present formulation. As numerical examples, an edge cracked plate and the specimen with a circular hole under plane stress are taken. Load-displacement curves and successively fractured shapes are shown. From the results, it can be concluded that the proposed model based on the local approach concept in the continuum damage mechanics may be stated as a reasonable tool to explain ductile fracture initiation and crack propagation.

• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.146-146
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• 1996

Although knowledge discovery is increasingly important in databases, the discovered knowledge sets may not be effectively used for application domains. It is partly because knowledge discovery does not take user's interests into account, and too many knowledge sets are discovered to handle efficiently. We believe that user's interests are conveyed by a query and if a nested query is concerned it may include a user's thought process. This paper describes a novel concept for discovering knowledge sets based on query processing. Knowledge discovery process is performed by: extracting features from databases, spanning features to generate range features, and constituting a knowledge set. The contributions of this paper include the following: (1) not only simple queries but also nested queries are considered to discover knowledge sets regarding user's interests and user's thought process, (2) not only positive examples (answer to a query) but also negative examples are considered to discover knowledge sets regarding database abstraction and database exceptions, and (3) finally, the discovered knowledge sets are quantified.

• 대한조선학회지
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• 제22권3호
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• pp.19-26
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• 1985

This paper deals with the representation and fairing of ship hull using a B-spline surface which is known as a 3-D model in computer aided free-form design. The first part of this paper is devoted to the fundamental concepts of B-spline theory and its geometrical characteristics. In its second part are described the facillities for efficient application, fast rendering of B-spline surface, and intersection of B-spline surfaces. The examples are presented with actual application to a real ship in the last part. And also a new concept of evaluating the surface fairness by the Gaussian curvature isolines is briefly discussed and its examples are presented.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권3호
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• pp.311-328
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• 2018

In school mathematics, the concept of an average is not a concept that is limited to a unit of statistics. In particular, high school students will learn about arithmetic mean and geometric mean in the process of learning absolute inequality. In calculus learning, the concept of average is involved when learning the concept of average speed. The arithmetic mean is the same as the procedure used when students mean the test scores. However, the procedure for obtaining the geometric mean differs from the procedure for the arithmetic mean. In addition, if the arithmetic mean and the geometric mean are the discrete quantity, then the mean rate of change or the average speed is different in that it considers continuous quantities. The average concept that students learn in school mathematics differs in the quantitative nature of procedures and objects. Nevertheless, it is not uncommon to find out how students construct various mathematical concepts into mathematical knowledge. This study focuses on this point and conducted the interviews of the students(three) in the second grade of high school. And the expression of students in the process of average concept formation in arithmetic mean, geometric mean, average speed. This study can be meaningful because it suggests practical examples to students about the assertion that various scholars should experience various properties possessed by the average. It is also meaningful that students are able to think about how to construct the mean conceptual properties inherent in terms such as geometric mean and mean speed in arithmetic mean concept through interview data.

• Structural Engineering and Mechanics
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• 제41권6호
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• pp.735-750
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• 2012

This paper presents a comparison between two different procedures to deal with the geometric nonlinear analysis of space trusses, considering its structural stability aspects. The first nonlinear formulation, called positional, uses nodal positions rather than nodal displacements to describe the finite elements kinematics. The strains are computed directly from the proposed position concept, using a Cartesian coordinate system fixed in space. The second formulation, called corotational, is based on the explicit separation between rigid body motion and deformed motion. The numerical examples demonstrate the performances and the convergence of the responses for both analyzed formulations. Two numerical examples were compared, including a lattice beam with postcritical behavior. Despite the two completely different approaches to deal with the geometrical nonlinear problem, the results present good agreement.

• 한국가구학회지
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• 제19권4호
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• pp.260-272
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• 2008

The recent concept of kitchen is likely defined as "Kitchen Culture" including the function of living room where all families make a conversation as well as a dinner, and it is becoming another type of the residential environment, deviating from the stereotype as only cooking area. Particularly the comfortableness of living room is closely associated with a receipt function of kitchen, and the sort & dimension & size of furniture and diversity of shapes playa more meaningful role for improving our life standard & comfortableness compared with the past, nevertheless this receipt study is carelessly handled in the first phase of construction. This Study is focusing on understanding the modern concept of kitchen where the open space concept is being introduced as more reasonable space concept, and on suggesting a solution for receipt-function of the modern kitchen concept connected with "L-D-K (Living room - Dining room- Kitchen)" space idea. In the Chapter 2 the concept of receipt and function of kitchen, the wide variety of kitchen utensils was checked up, and in the Chapter 3 the change of trends of kitchen area & receipt space was considered, and finally in the Chapter 4 the modern concept of kitchen was presented, by instancing overseas examples with receipt planning. As a consequence, the alternative of the receipt in the modern kitchen is to install an Ireland table or another type of receipt-available table (lower furniture) in the dead space between kitchen & living room for motivating smooth communication and convenient receipt, and that is the trend nowadays. Kitchen desires a rapid change. Through this kind of study it should be more researched that kitchen is not an independent space any more and lies in the mutual connection of L-D-K.