• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1728-1729
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• 2007

This paper presents an adaptive neural dynamic surface control (DSC) approach with $H_{\infty}$ tracking performance for a full dynamics of a nonlinear flight system. It is assumed in this paper that model uncertainties such as structured and unstrutured uncertainties and external disturbances influence the nonlinear aircraft model. In our control system, self recurrent wavelet neural networks (SRWNNs) are used to compensate model uncertainties of the nonlinear flight system, and an adaptive DSC technique is extended for disturbance attenuation of the nonlinear flight system. From Lyapunov stability theorem, it is shown that $H_{\infty}$ performance from external disturbances can be obtained. Finally, we perform the simulation for the nonlinear six-degree-of-freedom F-16 aircraft model to confirm the effectiveness of the proposed control system.

• Journal of Navigation and Port Research
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• v.32 no.2
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• pp.141-148
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• 2008

This paper is structured into three main parts and a conclusion. The main section provide definitions of efficiency, effectiveness and performance in terms of the distribution channel, followed by a review of related performance measurement, before discussing difficulties of measurement. According to the theoretical approach, it appears that key theroretical issues are centered around customer service, logistics excellence, time compression, the use of IT, and a move towards integrated logistics. The empirical approach shows that in the past, various financial performance indicators were regarded as relevant management information. However, today, management needs additional performance indicators. Therefore, external assessments of effectiveness must be performed to measure customers' satisfaction with the physical flow of product through the distribution channel network. So, what is needed is to take previous normative and explorative research and progress through a framework by developing valid measures of distribution channel's effectiveness and efficiency, and identifying research methodologies suited to the data collection requirements.

• Educational Technology International
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• v.20 no.1
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• pp.83-107
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• 2019

The aim of this study is to provide the values and descriptive implications of the Design Thinking (DT) method into the context of educational problems of practice in an undergraduate course. To achieve the research objective, both quantitative and qualitative studies were conducted. For the qualitative study, the student's productions and reflections on the experience of the application of the DT into educational problems were analyzed. For the quantitative research, one-group pre and post-test were designed to validate the effectiveness of the DT method into educational contexts in terms of creativity level to measure the student's Creativity Potential and Practiced Creativity, Academic Self-Efficacy Scale, and Problem-Solving Inventory. This study validated that the DT method had a statistically significant influence on those three competencies and also illustrated the detailed process from a qualitative viewpoint. The results and implications reflect the potential of the DT approach with the educational problem of practice, especially, in the ill-structured problem-solving contexts for student-centered instructional setting.

• Journal of the Korean Society of Visualization
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• v.21 no.3
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• pp.15-22
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• 2023

This research introduces an innovative approach for fabricating microstructure surfaces using spray-coating deposition. The resulting surface, referred to as Magnetically Responsive Microstructures (MRM), exhibits hierarchically structured micro-pillar arrays with remarkably high aspect ratios. The fabrication process involves precisely mixing PDMS and hexane with Carbonyl iron powders, followed by ultrasonication and spray-coating on the top of a PDMS substrate placed on the neodymium magnet. The MRM surface shows hydrophobic properties, characterized by a contact angle surpassing 150° and an aspect ratio exceeding 10. Through a comprehensive exploration of critical parameters, including spray amount, magnet-substrate distance, and solution ratio enhanced dynamic tunability and exceptional hydrophobic characteristics are attained. This novel approach holds significant potential for diverse applications in the realm of dynamically tunable microstructures and magnetically responsive surfaces.

• Journal of The Korean Association For Science Education
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• v.28 no.3
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• pp.211-226
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• 2008

The purpose of this study was to investigate science teachers' understandings about scientific argumentation in the classroom. Seven structured interview protocols were developed, asking the definition of scientific inquiry, the differentiation between scientific inquiry and hands-on activity, the opportunity of student argumentation, explicit teaching strategies for scientific argumentation, the critical example of argumentation, the criteria of successful argumentation, and the barrier of developing argumentation. The results indicate that there are differences and similarities in understandings about scientific argumentation between two groups of middle school teachers and upper elementary. Basically, teachers at middle school define scientific inquiry as the opportunity of practicing reasoning skills through argumentation, while teachers at upper elementary define it as the more opportunities of practicing procedural skills through experiments rather than of developing argumentation. Teachers in both groups have implemented a teaching strategy called "Claim-Evidence Approach," for the purpose of providing students with more opportunities to develop arguments. Students' misconception, limited scientific knowledge and perception about inquiry as a cycle without the opportunity of using reasoning skills were considered as barriers for implementing authentic scientific inquiry in the classroom.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.11-18
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• 2023

This study explores a new energy partitioning approach to determine the fracture toughness of 3-D printed pristine/recycled high density polyethylene (HDPE) blends employing the essential work of fracture (EWF) concept. The traditional EWF approach conducts a uniaxial tensile test with double-edge notched tensile (DENT) specimens and measures the total energy defined by the area under a load-displacement curve until failure. The approach assumes that the entire total energy contributes to the fracture process only. This assumption is generally true for extruded polymers that fracture occurs in a material body. In contrast to the traditional extrusion manufacturing process, the current 3-D printing technique employs fused deposition modeling (FDM) that produces layer-by-layer structured specimens. This type of specimen tends to include separation energy even after the complete failure of specimens when the fracture test is conducted. The separation is not relevant to the fracture process, and the raw experimental data are likely to possess random variation or noise during fracture testing. Therefore, the current EWF approach may not be suitable for the fracture characterization of 3-D printed specimens. This paper proposed a new energy partitioning approach to exclude the irrelevant energy of the specimens caused by their intrinsic structural issues. The approach determined the energy partitioning location based on experimental data and observations. Results prove that the new approach provided more consistent results with a higher coefficient of correlation.

• The KIPS Transactions:PartB
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• v.8B no.6
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• pp.657-668
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• 2001

It is difficult that web documents are classified with exact user intention because existing document classification systems are based on word frequency number using single keyword. To improve this defect, first, we use keyword, a query, domain knowledge. Like explanation based learning, first, query is analyzed with knowledge based information and then structured user intention information is extracted. We use this intention tree in the course of existing word frequency number based document classification as user information and constraints. Thus, we can classify web documents with more exact user intention. In classifying document, structured user intention information is helpful to keep more documents and information which can be lost in the system using single keyword information. Our hybrid approach integrating user intention information with existing statistics and probability method is more efficient to decide direction and range of document category than existing word frequency approach.

• Journal of KIISE:Software and Applications
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• v.31 no.7
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• pp.869-882
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• 2004

This paper proposes an effective method to create logically consistent and structured requirement model by applying consistency control approach of the formal method to the use-case modeling. This method integrates the multi-perspective scattered requirement segments that may overlap and conflict each other into a structured requirement model. The model structure can be analyzed based on context goal and concerned area overlap analysis. The model consistency can be achieved by using specification overlap-based consistency checking method as an integration vehicle. An experimental application to case study shows that the Proposed method can successfully identify requirement overlaps and inconsistency. It can also transfer multi-viewpoint requirement segments into a consistently integrated use-case model to clarify software behaviors and functionality This method helps users to enhance capability to identify specification inconsistency in the use-case modeling at the early stage of software engineering development. The proposed approach can also facilitate communication between users and developers to ensure customer satisfaction.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.95-98
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• 2005

This paper presents intelligent digital redesign method of global approach for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated linear operators to be matched. Also by using the power series, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete -time system have proper reason. Sufficiently conditions for the global state -matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMls). Finally, we prove the effectiveness and stabilization of the proposed intelligent digital redesign method by applying the chaotic Lorentz system.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.3
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• pp.197-214
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• 1996

Financial analysis of stock data usually involves extensive computation of large amount of time series data sets. To handle the large size of the data sets and complexity of the analyses, database management systems have been increasingly adaopted for efficient management of stock data. Specially, relational database management system is employed more widely due to its simplistic data management approach. However, the normalized two-dimensional tables and the structured query language of the relational system turn out to be less effective than expected in accommodating time series stock data as well as the various computational operations. This paper explores a new data management approach to stock data management on the basis of an object-oriented database management system (ODBMS), and proposes a data model supporting times series data storage and incorporating a set of financial analysis functions. In terms of functional stock data analysis, it specially focuses on a primitive set of operations such as variance of stock data. In accomplishing this, we first point out the problems of a relational approach to the management of stock data and show the strength of the ODBMS. We secondly propose an object model delineating the structural relationships among objects used in the stock data management and behavioral operations involved in the financial analysis. A prototype system is developed using a commercial ODBMS.