• International Journal of Fuzzy Logic and Intelligent Systems
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• v.11 no.3
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• pp.149-152
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• 2011

In this paper, we obtain common fixed point theorem for common property(E.A.) and weakly compatible functions in intuitionistic fuzzy metric space.

• Korean Journal of Computational Design and Engineering
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• v.12 no.3
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• pp.220-232
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• 2007

Current geometric modeling and analysis are commonly based on B-Rep modeling and a finite elements method respectively. Furthermore, it is difficult to represent an object whose material property is heterogeneous using the B-Rep method because the B-Rep is basically used for homogeneous models. In addition, meshes are required to analyze a property of a model when the finite elements method is applied. However, the process of generating meshes from B-Rep is cumbersome and sometimes difficult especially when the model is deformed as time goes by because the topology of deforming meshes are changed. To overcome those problems in modeling and analysis including homogeneous and heterogeneous materials, we suggest a unified modeling and analysis method based on implicit representation of the model using R-function which is suggested by Rvachev. For implicit modeling of an object a distance field is approximated and blended for a complex object. Using the implicit function mesh-free analysis is possible where meshes are not necessary. Generally mesh-free analysis requires heavy computational cost compared to a finite elements method. To improve the computing time of function evaluation, we utilize GPU programming. Finally, we give an example of a simple pipe design problem and show modeling and analysis process using our unified modeling and analysis method.

• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.795-812
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• 2013

The merit function arises from the development of the solution methods for the complementarity problems defined over the cone of non negative real vectors and has been well extended to the complementarity problems defined over the symmetric cones. In this paper, we focus on the extension of the merit functions including the gap function, the regularized gap function, the implicit Lagrangian and others to the complementarity problems defined over the nonsymmetric matrix cone. These theoretical results of this paper suggest new solution methods based on unconstrained and/or simply constrained methods to solve the matrix cone complementarity problems (MCCP).

• Communications of the Korean Mathematical Society
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• v.24 no.1
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• pp.41-55
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• 2009

A general common fixed point theorem for two pairs of weakly compatible mappings using an implicit function is proved without any continuity requirement which generalizes the result due to Popa [20, Theorem 3]. In process, several previously known results due to Fisher, Kannan, Jeong and Rhoades, Imdad and Ali, Imdad and Khan, Khan, Shahzad and others are derived as special cases. Some related results and illustrative examples are also discussed. As an application of our main result, we prove an existence theorem for the solution of simultaneous Hammerstein type integral equations.

• Knowledge Management Research
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• v.2 no.1
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• pp.65-81
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• 2001

The aim of this study is classify knowledge work style management for knowledge management. It is based on the knowledge creation model of Nonaka by subdividing types of knowledge workers. It was designed to create a model for application to the actual environment of management. Nonaka suggested the process of socialization, externalization, combination, internalization that the knowledge of a person creates new knowledge through the interaction of implicit knowledge and explicit knowledge. This research demonstrated that knowledge worker of 16 forms by applying SECI model to the main function and the subordinate functions again. This study aims at achieving a higher outcome by applying the ability of existing knowledge worker to subdivided expert field efficiently. Suggested styles of knowledge worker in this research are classified into craftsman style, pragmatic style, combination style, developed style knowledge worker who creates knowledge by selecting socialization as the function and again by selecting externalization combination, internalization as subordinate functions. And they were classified into creation style, insight style, strategy style according to practical application worker and function which is selecting externalization as the main function and socialization as the subordinate functions. They were classified into future style, innovation style, analysis style, judgement style knowledge worker who are selecting combination as the main function and experiment style, intuition style, research style, learning style worker who are selecting internalization as the main function. They suggested the characteristics and cases of each type.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.369-379
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• 2023

Reliability-Based Design Optimization (RBDO) is an appropriate framework for obtaining optimal designs by taking uncertainties into account. Large-scale problems with implicit limit state functions and problems with discrete design variables are two significant challenges to traditional RBDO methods. To overcome these challenges, this paper proposes a hybrid method to perform RBDO of structures that links Firefly Algorithm (FA) as an optimization tool to advanced (finite element) reliability methods. Furthermore, the Genetic Algorithm (GA) and the FA are compared based on the design cost (objective function) they achieve. In the proposed method, Weighted Simulation Method (WSM) is utilized to assess reliability constraints in the RBDO problems with explicit limit state functions. WSM is selected to reduce computational costs. To performing RBDO of structures with finite element modeling and implicit limit state functions, a First-Order Reliability Method (FORM) based on the Direct Differentiation Method (DDM) is utilized. Four numerical examples are considered to assess the effectiveness of the proposed method. The findings illustrate that the proposed RBDO method is applicable and efficient for RBDO problems with discrete and continuous design variables and finite element modeling.

• Steel and Composite Structures
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• v.47 no.5
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• pp.569-585
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• 2023

This paper proposes an efficient approach for the structural topology optimization of bi-directional functionally graded structures by incorporating popular radial basis functions (RBFs) into an implicit level set (ILS) method. Compared to traditional element density-based methods, a level set (LS) description of material boundaries produces a smoother boundary description of the design. The paper develops RBF implicit modeling with multiquadric (MQ) splines, thin-plate spline (TPS), exponential spline (ES), and Gaussians (GS) to define the ILS function with high accuracy and smoothness. The optimization problem is formulated by considering RBF-based nodal densities as design variables and minimizing the compliance objective function. A LS-RBF optimization method is proposed to transform a Hamilton-Jacobi partial differential equation (PDE) into a system of coupled non-linear ordinary differential equations (ODEs) over the entire design domain using a collocation formulation of the method of lines design variables. The paper presents detailed mathematical expressions for BiDFG beams topology optimization with two different material models: continuum functionally graded (CFG) and mechanical functionally graded (MFG). Several numerical examples are presented to verify the method's efficiency, reliability, and success in accuracy, convergence speed, and insensitivity to initial designs in the topology optimization of two-dimensional (2D) structures. Overall, the paper presents a novel and efficient approach to topology optimization that can handle bi-directional functionally graded structures with complex geometries.

• Korean Journal of Culture and Social Issue
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• v.18 no.4
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• pp.463-479
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• 2012

The implicit association test (IAT) measures implicit attitudes of participants and is regarded as an effective method for expecting future behaviors. Based on the IAT, this study aimed to answer the question, whether implicit attitudes of an individual about creativity have any kinds of impact on global perception, which might be important for a creative process. In the experiment, participants were presented words, which were associated with one of four categories, while one attitude category (creativity /practicality) and one evaluative category (good/bad) were always paired together either on the left side or on the right side of the computer screen. After completing the IAT test, participants were led to fill out a questionnaire to assess explicit attitudes toward creativity and practicality. Then they conducted the navon task, in which they had to find one of two letters, 'F' or 'H', which were presented either as a local form or as a global form. Finally, the participants had to write down as many untypical functions of an object as possible. The results showed that not the scores of explicit attitude scores but the IAT scores correlated with the reaction time of global perception. The global perception was faster in the participants with the low IAT scores than the local perception. Compared to this, the global perception benefits disappeared in the participants with the high IAT scores. Additionally, more creative ideas about the functions of the object were listed in the group with the lower IAT scores. Implications of the role of implicit attitudes about creative processes are discussed.

• Journal of the Korea Computer Graphics Society
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• v.2 no.1
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• pp.31-38
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• 1996

Many efforts for finding smooth curves and surfaces satisfying given constraints have been made, and interpolation and approximation theories with the help of computers have played an important role in this endeavour. Most research in curve and surface modeling has been largely dominated by the theory of parametric representations. While they have been successfully used in representing physical objects, parametric surfaces are confronted with some problems when objects are represented and manipulated in geometric modeling systems. In recent year, increasing attention has been paid to implicit algebraic surfaces since they are often more effective than parametric surfaces are. In this paper, we summarize the geometric properties and computational processes of objects represented using implicit algebraic functions and explain of the implementation of design tools which can design curves and surfaces of revolution. These surfaces of revolution are played an importance role in effective areas such as CAD and CAM.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.05a
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• pp.247-250
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• 2003

Due to the increasing use of very large databases, mining useful information and implicit knowledge from databases is evolving. However, most conventional data mining algorithms identify the relationship among features using binary values (TRUE/FALSE or 0/1) and find simple If-THEN rules at a single concept level. Therefore, implicit knowledge and causal relationships among features are commonly seen in real-world database and applications. In this paper, we thus introduce the mechanism of mining fuzzy association rules and constructing causal knowledge base form database. Acausal knowledge base construction algorithm based on Fuzzy Cognitive Map(FCM) and Srikant and Agrawal's association rule extraction method were proposed for extracting implicit causal knowledge from database. Fuzzy association rules are well suited for the thinking of human subjects and will help to increase the flexibility for supporting users in making decisions or designing the fuzzy systems. It integrates fuzzy set concept and causal knowledge-based data mining technologies to achieve this purpose. The proposed mechanism consists of three phases: First, adaptation of the fuzzy membership function to the database. Second, extraction of the fuzzy association rules using fuzzy input values. Third, building the causal knowledge base. A credit example is presented to illustrate a detailed process for finding the fuzzy association rules from a specified database, demonstration the effectiveness of the proposed algorithm.