• Title/Summary/Keyword: Systems Analysis and Design

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Robust Guaranteed Performance Control of Uncertain Linear Systems (불확정성 선형 시스템의 강인 성능 보장 제어)

  • Kim, Jin-Hoon
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.5
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    • pp.553-559
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    • 1999
  • The robust control problem of the linear systems with uncertainty is classified as the robust stability problem guaranteeing the stability and the robust performance problem guaranteeing the disired performance. In this paper, we considered the robust performance analysis problem, which find the upper buund of the quadratic performance of the uncertain linear system, and the robust guaranteed performance controller design problem which design a controller guaranteeing the desired quadratic performance. At first, we treated the analysis problem and presented the two results; one is dependent on the performance of the nominal system and another is independent on this. And we treated the design method guaranteeing the desired performance for the uncertain linear systems, Finally, we show the usefulness of our results by numerical examples.

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A Study on the Philosophical Analysis Model and its Methodological Application of Information Systems Research.Evaluation - A Critical Realist Approach - (정보체계 탐구.평가의 철학적 분석 모델과 그 방법론적 활용: 비판 실재론적 접근)

  • Ko, Chang-Taek
    • The Journal of Information Systems
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    • v.16 no.4
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    • pp.131-155
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    • 2007
  • The purpose of this thesis is to study on the philosophical analysis model and its methodological application of information systems research evaluation from critical realist perspective. Fist of all, I examine ontological epistemological methodological assertions of critical realism. Because the philosophy of critical realism is an opportunity for information systems study. I examine Dobson and Mutch's critical realist perspective on actors-structure model. I suggest a critical realist actors-praxis-structure model. This model provides the potential for a new approach to social investigations in its provision of an ontology for the analytical separation of structure and agency. Of most importance might be the incorporation of non-humans into the analysis of social interaction and of technology into the elaboration of structures. I also examine Tsoukas's critical realistic meta-theory of management. I suggest a critical realist IS management model. This model elucidate the nature of management and delineate the scope of applicability of various perspectives on management. The causal powers of management reside in the real domain and, taken together, their logics are contradictory, the effects of their contradictory composition are contingent upon prevailing contingencies. I analyze Carlsson's theory of design knowledge. His framework builds on that the aim of IS design science research is to develop practical knowledge for the design and realization of different classes of IS initiatives, where IS are viewed as socio-technical systems and not just IT artefacts. The framework proposes that the output of IS design science research is practical IS design knowledge in the form of field-tested and grounded technological rules. The IS design knowledge is developed through an IS design science research cycle. In conclusion, I think that IS actors-praxis-structure model, meta-theoretical IS management model, and IS design knowledge model according to critical realistic approach are very useful for IS research evaluation. Nevertheless, important problems are left not resolved.

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Advanced Design Synthesis Process for Rapid Aircraft Development (신속한 항공기 개발을 위한 통합 개념설계 프로세스에 대한 연구)

  • Park, Seung Bin;Park, Jin Hwan;Jeon, Kwon-Su;Kim, Sangho;Lee, Jae-Woo
    • Journal of the Korean Society of Systems Engineering
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    • v.9 no.2
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    • pp.83-90
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    • 2013
  • Integrated aircraft synthesis process for rapid analysis and design is described in this paper. Data flow between different analysis fields is described in details. All the data are divided into several groups according to importance and source of the data. Analysis of design requirements and certification regulations is carried out to determine baseline configuration of an aircraft. Overall design process can be divided into initial sizing, conceptual and preliminary design phases. Basic data for conceptual design are obtained from initial sizing, CAD and geometry analysis. Basic data are required input for weight, aerodynamics and propulsion analyses. Results of this analysis are used for stability and control, performance, mission, and load analysis. Feasibility of design is verified based on analysis results of each discipline. Design optimization that involves integrated process for aircraft analysis is performed to determine optimum configuration of an aircraft on a conceptual design stage. The process presented in this paper was verified to be used for light aircraft design.

Feature-Based Non-manifold Geometric Modeling System to Provide Integrated Environment for Design and Analysis of Injection Molding Products (사출 성형 제품의 설계 및 해석의 통합 환경을 제공하기 위한 특징 형상 기반 비다양체 모델링 시스템의 개발)

  • 이상헌;이건우
    • Korean Journal of Computational Design and Engineering
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    • v.1 no.2
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    • pp.133-149
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    • 1996
  • In order to reduce the trial-and-errors in design and production of injection molded plastic parts, there has been much research effort not only on CAE systems which simulate the injection molding process, but also on CAD systems which support initial design and re-design of plastic parts and their molds. The CAD systems and CAE systems have been developed independently with being built on different basis. That is, CAD systems manipulate the part shapes and the design features in a complete solid model, while CAE systems work on shell meshes generated on the abstract sheet model or medial surface of the part. Therefore, it is required to support the two types of geometric models and feature information in one environment to integrate CAD and CAE systems for accelerating the design speed. A feature-based non-manifold geometric modeling system has been developed to provide an integrated environment for design and analysis of injection molding products. In this system, the geometric models for CAD and CAE systems are represented by a non-manifold boundary representation and they are merged into a single geometric model. The suitable form of geometric model for any application can be extracted from this model. In addition, the feature deletion and interaction problem of the feature-based design system has been solved clearly by introducing the non-manifold Boolean operation based on 'merge and selection' algorithm. The sheet modeling capabilities were also developed for easy modeling of thin plastic parts.

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Kinematic Design Sensitivity Analysis of Vehicle Suspension Systems using a Numerical Differentiation Method (수치미분에 의한 차량 현가장치의 기구학적 민감도 해석)

  • 탁태오
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.5
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    • pp.128-137
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    • 1998
  • A numerical approach for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. Compared with the conventional analytical methods, which require explicit derivation of sensitivity equations, the proposed numerical method can be applied to any type of suspension systems without obtaining sensitivity equations, once any kinematic analysis procedure is established. To obtain sensitivity equations, a numerical differentiation algorithm that uses the third order Lagrange polynomial is developed. The algorithm efficiently and accurately computes the sensitivity of various vehicle static design factors with respect to kinematic design variables. Through a suspension design problem, the validity and usefulness of the method is demonstrated.

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Efficient non-linear analysis and optimal design of biomechanical systems

  • Shojaei, I.;Kaveh, A.;Rahami, H.;Bazrgari, B.
    • Biomaterials and Biomechanics in Bioengineering
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    • v.2 no.4
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    • pp.207-223
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    • 2015
  • In this paper a method for simultaneous swift non-linear analysis and optimal design/posture of mechanical/biomechanical systems is presented. The method is developed to get advantages of iterations in non-linear analysis and/or generations in genetic algorithm (GA) for the purpose of efficient analysis within the optimal design/posture. The method is applicable for both size and geometry optimizations wherein material and geometry non-linearity are present. In addition to established mechanical systems, the method can solve biomechanical models of human musculoskeletal system. Optimization-based procedures are popular methods for resolving the redundancy at joints wherein the number of unknown muscle forces is far more than the number of equilibrium equations. These procedures involve optimization of a cost function(s) which is assumed to be consistent with the central nervous system's strategy when activating muscles to assure equilibrium. However, because of the complexity of biomechanical problems (i.e., due to non-linear biomaterial, large deformation, redundancy of the problem and so on) efficient analysis are required within optimization procedures as suggested in this paper.

Development of Water-Cooled Heat Sink for High-Power IGBT Inverter

  • Han, Min-Sub;Lee, Su-Dong;Hong, Chan-Ook;Yang, Chun-Suk;Kim, Kyung-Seo
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.349-353
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    • 2008
  • We present the development of a water-cooled heat sink that provides reliable thermal performance for high-power IGBT inverter. The development process comprises three stages. In the concept design, the thermal performances of two design proposals are considered. The thermal system of each design is particularly analyzed using the compact model. In the detailed design stage, specific dimensions of the heat sink are determined considering the design options under given external restrictions and the results from three-dimensional heat transfer analysis. The prototype of the resultant design is made and tested on the rig for final confirmation. We emphasize the relevant use of the thermal analysis on each stage and also discuss various practical issues involved.

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Knowledge Modeling of Reliability Analysis and Safety Design for Offshore Safety Instrument System with MBSE (Model-Based Systems Engineering) (모델기반 시스템엔지니어링을 활용한 해양플랜트 안전시스템(SIS, Safety Instrumented System)의 신뢰도 분석 및 안전설계 지식 모델링)

  • Bae, Jeong-hoon;Jung, Min-jae;Shin, Sung-chul
    • Journal of the Society of Naval Architects of Korea
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    • v.55 no.3
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    • pp.222-235
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    • 2018
  • The hydrocarbon gas leak in the offshore plant can cause large accidents and lead to significant damages to human, property and environment. For prevention of fire or explosion accidents from gas leak, a SIS(Safety Instrumented System) should be installed. In the early stage of the offshore design, required SIL(Safety Integrated Level) is determined and reliability analysis is performed to verify the design in reliability aspects. This study collected data, information related to reliability analysis and created knowledge model of safety design for the offshore system with MBSE(Model-Based Systems Engineering) concept. Knowledge model could support safety engineer's design tasks as the guidance of reliability analysis procedure of safety design and make good conversation with other engineers in yard, class, company, etc.

An Adjoint Variable Method for Eigenproblem Design Sensitivity Analysis of Damped Systems (감쇠계 고유치문제의 설계민감도해석을 위한 보조변수법)

  • Lee, Tae Hee;Lee, Jin Min;Yoo, Jung Hoon;Lee, Min Uk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.11 s.242
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    • pp.1527-1533
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    • 2005
  • Three methods for design sensitivity analysis such as finite difference method(FDM), direct differentiation method(DDM) and adjoint variable method(AVM) are well known. FDM and DDM for design sensitivity analysis cost too much when the number of design variables is too large. An AVM is required to compute adjoint variables from the simultaneous linear system equation, the so-called adjoint equation. Because the adjoint equation is independent of the number of design variables, an AVM is efficient for when number of design variables is too large. In this study, AVM has been extended to the eigenproblem of damped systems whose eigenvlaues and eigenvectors are complex numbers. Moreover, this method is implemented into a commercial finite element analysis program by means of the semi-analytical method to show applicability of the developed method into practical structural problems. The proposed_method is compared with FDM and verified its accuracy for analytical and practical cases.

Development of An Optimal Design Program for Open-Chain Dynamic Systems (불구속연쇄 동적시스템을 위한 최적설계 프로그램 개발)

  • 최동훈;한창수;이동수;서문석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.1
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    • pp.12-23
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    • 1994
  • This paper proposes an optimal design software for the open-chain dynamic systems whose governing equations are expressed as differential equation. In this software, an input module and an automatic creation module of the equation of motion are developed to contrive the user's convenience. To analyze the equation of motion of the dynamic systems, variable-order and variable-stepsize Adams-Bashforth-Moulton predictor-corrector method is used to improve the efficiency. For the optimization and the design sensitivity analysis, ALM(augmented lagrange multiplier)method and adjoint variable method are adopted respectively. An output module with which the user can compare and investigate the analysis and the optimization results through tables and graphs is also provided. The developed software is applied to three typical dynamic response optimization problems, and the results compare very well with those available in the literature, demonstrating its effectiveness.