• Title/Summary/Keyword: matrix problems

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Leveraging and Fostering Diversity in the IS Discipline: Intradisciplinary Knowledge Building via the IT View-IS Phenomenon (VP) Matrix

  • Inchan Kim;Jama Summers
    • Asia pacific journal of information systems
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    • v.34 no.1
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    • pp.49-90
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    • 2024
  • Intradisciplinary research refers to research that integrates ideas often associated with different research domains in a discipline. Such cross-fertilization leverages abundant diversity present in the IS discipline to tackle increasingly complex IS problems and grand challenges. Despite its importance and recent attention, a concerted, sustained effort toward intradisciplinary research is lagging. A fundamental issue we see is a lack of an elaborate IS research map that effectively shows similarities and differences among research domains and demonstrates types of ideas that may travel and integrate into different domains. We thus aim to propose an elaborate IS research map and compile research elements that can be tried and combined across research domains. To do so, we utilize two IS classics (i.e., IT views and IS phenomena), identify their complementarity, and interweave the two disparate ways of portraying the IS research field. The resultant view-phenomenon (VP) matrix specifies research domains based on two consistent, comprehensive criteria and helps researchers discern similarities and differences among research domains more effectively. The VP matrix also sheds light on a variety of research elements that can flow across research domains. The VP matrix along with the research elements together facilitate intradisciplinary efforts and, more broadly, help the IS discipline to prosper. The VP matrix is particularly helpful for doctoral students and young scholars.

Fabrication of PP/Carbon Fiber Composites by Introducing Reactive Interphase and its Properties (반응성 고분자 계면상을 도입한 PP/탄소섬유 복합재료의 제조와 물성)

  • 김민영;김지홍;김원호;최영선;황병선
    • Polymer(Korea)
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    • v.24 no.4
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    • pp.556-563
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    • 2000
  • In general, the development of thermoplastic composites has been confronted with difficult problems such as the weak bonding strength between fibers and matrix. However, now, such problems are being surmounted by the development of resins, the improvement of processes, and introduction of interphase. Especially, the introduction of interphase between fiber and matrix can help a dissipation of the impact energy and provide a good adhesion between fibers and matrix. In this study, polymeric interphase was introduced by electrodeposition, modified polypropylene was added to improve the weak bonding strength between interphase and polypropylene matrix. By evaluation of interlaminar shear strength and impact strength of the composites, it was found that composites with introduced composites showed higher mechanical properties than those of composites without interphase. Reactive polymers which have either anhydride or free acid functional group were used as interphase materials, and these polymers also behave as charge carrier in aqueous solution during the electrodeposition process. Weight gain on the carbon fibers was evaluated by changing process parameters such as concentration of solution, current density, and electrodeposition time.

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Effects of Anisotropic Fiber Packing on Stresses in Composites (이방성 섬유의 배열이 복합재료의 응력에 미치는 영향)

  • Lee, Jung-Ki;Lee, Hyeong-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.9
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    • pp.1284-1296
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    • 2004
  • In order to investigate effects of anisotropic fiber packing on stresses in composites, a Volume Integral Equation Method is applied to calculate the elastostatic field in an unbounded isotropic elastic medium containing multiple orthotropic inclusions subject to remote loading, and a Mixed Volume and Boundary Integral Equation Method is introduced for the solution of elastostatic problems in unbounded isotropic materials containing multiple anisotropic inclusions as well as one void under uniform remote loading. A detailed analysis of stress fields at the interface between the isotropic matrix and the central orthotropic inclusion is carried out for square, hexagonal and random packing of orthotropic cylindrical inclusions, respectively. Also, an analysis of stress fields at the interface between the isotropic matrix and the central orthotropic inclusion is carried out, when it is assumed that a void is replaced with one inclusion adjacent to the central inclusion of square, hexagonal and random packing of orthotropic cylindrical inclusions, respectively, due to manufacturing and/or service induced defects. The effects of random orthotropic fiber packing on stresses at the interface between the isotropic matrix and the central orthotropic inclusion are compared with the influences of square and hexagonal orthotropic fiber packing on stresses. Through the analysis of plane elastostatic problems in unbounded isotropic matrix with multiple orthotropic inclusions and one void, it will be established that these new methods are very accurate and effective for investigating effects of general anisotropic fiber packing on stresses in composites.

(Robust Non-fragile $H^\infty$ Controller Design for Parameter Uncertain Systems) (파라미터 불확실성 시스템에 대한 견실 비약성 $H^\infty$ 제어기 설계)

  • Jo, Sang-Hyeon;Kim, Gi-Tae;Park, Hong-Bae
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.39 no.3
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    • pp.183-190
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    • 2002
  • This paper describes the synthesis of robust and non-fragile H$\infty$ state feedback controllers for linear varying systems with affine parameter uncertainties, and static state feedback controller with structured uncertainty. The sufficient condition of controller existence, the design method of robust and non-fragile H$\infty$ static state feedback controller, and the set of controllers which satisfies non-fragility are presented. The obtained condition can be rewritten as parameterized Linear Matrix Inequalities(PLMls), that is, LMIs whose coefficients are functions of a parameter confined to a compact set. However, in contrast to LMIs, PLMIs feasibility problems involve infinitely many LMIs hence are inherently difficult to solve numerically. Therefore PLMls are transformed into standard LMI problems using relaxation techniques relying on separated convexity concepts. We show that the resulting controller guarantees the asymptotic stability and disturbance attenuation of the closed loop system in spite of controller gain variations within a degree.

A Study on the Robust Stability and Stabilization Problem for Marine Vessel (수상 및 수중 운동체의 강인 안정성 해석 및 안정화에 관한 연구)

  • Kim, Young-Bok;Cho, Kwang-Hwan
    • Journal of Navigation and Port Research
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    • v.36 no.5
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    • pp.379-385
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    • 2012
  • In this paper, the stability and stabilization problems for marine vessels including surface and underwater vehicles are described. In the marine vessels, there are many and strong nonlinear parameters. These give hard design process and difficulties to us. In this article, at first we make a descriptor system representation as a controlled system to preserve the physical parameters of the system as it is. And we propose a new stability and stabilizability conditions based on the quadratic stabilization approach which gives a solution for the unreasonable problems produced by added mass. That is, the proposed conditions are not interfered with the nonsymmetric matrix constraint. And the stability condition is given by an matrix inequality such that it makes us to obtain a solution easily for something.

TS Fuzzy Classifier Using A Linear Matrix Inequality (선형 행렬 부등식을 이용한 TS 퍼지 분류기 설계)

  • Kim, Moon-Hwan;Joo, Young-Hoon;Park, Jin-Bae
    • Journal of the Korean Institute of Intelligent Systems
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    • v.14 no.1
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    • pp.46-51
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    • 2004
  • his paper presents a novel design technique for the TS fuzzy classifier via linear matrix inequalities(LMI). To design the TS fuzzy classifier built by the TS fuzzy model, the consequent parameters are determined to maximize the classifier's performance. Differ from the conventional fuzzy classifier design techniques, convex optimization technique is used to resolve the determination problem. Consequent parameter identification problems are first reformulated to the convex optimization problem. The convex optimization problem is then efficiently solved by converting linear matrix inequality problems. The TS fuzzy classifier has the optimal consequent parameter via the proposed design procedure in sense of the minimum classification error. Simulations are given to evaluate the proposed fuzzy classifier; Iris data classification and Wisconsin Breast Cancer Database data classification. Finally, simulation results show the utility of the integrated linear matrix inequalities approach to design of the TS fuzzy classifier.

A Study on the Problems and Improvement Solutions for the Ambulance Stretcher (119구급대 주들것의 문제점과 그 개선방안에 관한 연구)

  • Ham, Seung Hee;Song, Woo Seung;Yoon, Myung O
    • Fire Science and Engineering
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    • v.28 no.3
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    • pp.72-79
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    • 2014
  • The purpose of this study is to draw the improvement plan through the analysis of problems of main stretchers that are being used by the 119 EMS. In order to find out the problems, we used the literature review and analysis, survey questionnaire and we also made full use of KJ method (Kawakita Jiro method, affinity diagram), graph method, and priority matrix method to produce the improvement indicators. The problems of main stretchers are summarized as follows. they are being recognized as part of the emergency vehicle, they have the imperfection of performance verification criteria, and they cause the injuries of paramedics and patients accidents in operation. The indicators such as the ease of operation, the high performance, the multi-function, the driving performance, the durability and the lightweight, was produced to improve the problems. The results of the interconnection analysis and the applying priority matrix method on the indicators are the ease of operation ${\rightarrow}$ the multi-function ${\rightarrow}$ the driving performance ${\rightarrow}$ the high performance ${\rightarrow}$ the durability and the lightweight in order of importance.

Numerical Modeling of Elastic Wave Scattering in an Isotropic Medium Containing an Orthotropic Inclusion (직교이방성 함유체를 포함하는 등방성 기지에서의 탄성파 산란 수치해석 모델)

  • Lee, Jung-Ki
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.1
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    • pp.69-79
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    • 2001
  • A volume integral equation method(VIEM) is applied for the effective analysis of elastic wave scattering problems in unbounded solids containing general anisotropic inclusions. It should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only the Green's function for the unbounded isotropic matrix is Involved In their formulation for the analysis. nis new method can also be applied to general two-dimensional elastodynamic problems with arbitrary shapes and number of anisotropic inclusions. Through the analysis of plane elastodynamic problems in unbounded isotropic matrix with an orthotropic inclusion, it is established that this new method is very accurate and effective for solving plane elastic problems in unbounded solids containing general anisotropic inclusions.

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An Empirical Data Driven Optimization Approach By Simulating Human Learning Processes (인간의 학습과정 시뮬레이션에 의한 경험적 데이터를 이용한 최적화 방법)

  • Kim Jinhwa
    • Journal of the Korean Operations Research and Management Science Society
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    • v.29 no.4
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    • pp.117-134
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    • 2004
  • This study suggests a data driven optimization approach, which simulates the models of human learning processes from cognitive sciences. It shows how the human learning processes can be simulated and applied to solving combinatorial optimization problems. The main advantage of using this method is in applying it into problems, which are very difficult to simulate. 'Undecidable' problems are considered as best possible application areas for this suggested approach. The concept of an 'undecidable' problem is redefined. The learning models in human learning and decision-making related to combinatorial optimization in cognitive and neural sciences are designed, simulated, and implemented to solve an optimization problem. We call this approach 'SLO : simulated learning for optimization.' Two different versions of SLO have been designed: SLO with position & link matrix, and SLO with decomposition algorithm. The methods are tested for traveling salespersons problems to show how these approaches derive new solution empirically. The tests show that simulated learning for optimization produces new solutions with better performance empirically. Its performance, compared to other hill-climbing type methods, is relatively good.

A Structural Relationship Among the Related Variables of Children's Internalizing and Externalizing Problems (아동의 내면화·외현화문제행동 관련변인들 간의 인과적 구조분석)

  • Moon, Dae-Geun;Moon, Soo-Back
    • Korean Journal of Child Studies
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    • v.32 no.5
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    • pp.49-65
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    • 2011
  • The purpose of this study was to investigate the structural relationship between the related variables of children's internalization and externalization of problems. A total of 709 elementary school students residing in Daegu City and Kyungpook province completed questionnaires which assessed family interaction functions, emotional regulation, self-control, and internalization and externalization of problems. The sample variance-covariance matrix was analyzed using AMOS 19.0, and a maximum likelihood minimization function. Goodness of fit was evaluated using the SRMS, RMSEA, and its 90% confidence interval, CFI, and TLI. The results were as follows : First, the function of family interaction, and emotional regulation had a significant direct effect on the internalization of problems. Moreover, emotional regulation, self-control and internalization of problems had a statistically substantial direct effect on the externalization of problems. Second, family interaction functions did not have a statistically significant direct on children's externalization of problems, although it may well have an indirect effect on children's externalization of problems through emotional regulation and self-control. Finally, self-control did not enjoy a direct effect on children's internalization of problems.