• Title/Summary/Keyword: Multi parameter

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Identification of Dynamic Joint Characteristics Using a Multi-domain FRF-based Substructuring Method (다중 전달함수합성법을 이용한 진동시스템의 결합부 특성 값 동정)

  • 이두호;황우석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.501-509
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    • 2003
  • A method of identifying structural parameters such as stiffness and damping coefficients at interfacial points of vibro-acoustic systems is suggested using an optimization technique. To identify the parameters using a numerical optimization algorithm, cost functions are defined. The cost function should be zero at the correct parameter values. To minimize the cost functions using an optimization technique, a design sensitivity analysis procedure is developed in the framework of the multi-domain FRF-based substructuring method. As a numerical example, a ladder-like structure problem is introduced. With known parameter values and different initial guesses of the parameters, convergence characteristics to the exact value are compared for the three cost functions. Investigating the contours of the cost functions, we find the first cost function has the largest convergent region to the correct value. As another practical problem, stiffnesses of engine mounts and bushings in a passenger car are identified. The numerical examples show that the proposed method is efficient and accurate even when applied to realistic problems.

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Prediction of Solvent Effects on Rate Constant of [2+2] Cycloaddition Reaction of Diethyl Azodicarboxylate with Ethyl Vinyl Ether Using Artificial Neural Networks

  • Habibi-Yangjeh, Aziz;Nooshyar, Mahdi
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.139-145
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    • 2005
  • Artificial neural networks (ANNs), for a first time, were successfully developed for the modeling and prediction of solvent effects on rate constant of [2+2] cycloaddition reaction of diethyl azodicarboxylate with ethyl vinyl ether in various solvents with diverse chemical structures using quantitative structure-activity relationship. The most positive charge of hydrogen atom (q$^+$), dipole moment ($\mu$), the Hildebrand solubility parameter (${\delta}_H^2$) and total charges in molecule (q$_t$) are inputs and output of ANN is log k$_2$ . For evaluation of the predictive power of the generated ANN, the optimized network with 68 various solvents as training set was used to predict log k$_2$ of the reaction in 16 solvents in the prediction set. The results obtained using ANN was compared with the experimental values as well as with those obtained using multi-parameter linear regression (MLR) model and showed superiority of the ANN model over the regression model. Mean square error (MSE) of 0.0806 for the prediction set by MLR model should be compared with the value of 0.0275 for ANN model. These improvements are due to the fact that the reaction rate constant shows non-linear correlations with the descriptors.

Enhancement of On-Resistance Characteristics Using Charge Balance Analysis Modulation in a Trench Filling Super Junction MOSFET

  • Geum, Jongmin;Jung, Eun Sik;Kim, Yong Tae;Kang, Ey Goo;Sung, Man Young
    • Journal of Electrical Engineering and Technology
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    • v.9 no.3
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    • pp.843-847
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    • 2014
  • In Super Junction (SJ) MOSFETs, charge balance is the most important issue of the SJ fabrication process. In order to achieve the best electrical characteristics, such as breakdown voltage and on-resistance, the N-type and P-type drift regions must be fully depleted when the drain bias approaches the breakdown voltage, which is known as the charge balance condition. In conventional charge balance analysis, based on multi-epi process SJ MOSFETs, analytical model has only N, P pillar width and doping concentration parameter. But applying a conventional charge balance principle to trench filling process, easier than Multi-epi process, is impossible due to the missing of the trench angle parameter. To achieve much more superior characteristics of on-resistance in trench filling SJ MOFET, the appropriate trench angle is necessary. So in this paper, modulated charge balance analysis is proposed, in which a trench angle parameter is added. The proposed method is validated using the TCAD simulation tool.

Probabilistic analysis of seismically isolated elevated liquid storage tank using multi-phase friction bearing

  • Moeindarbari, Hesamaldin;Malekzadeh, Masoud;Taghikhany, Touraj
    • Earthquakes and Structures
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    • v.6 no.1
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    • pp.111-125
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    • 2014
  • Multiple level performance of seismically isolated elevated storage tank isolated with multi-phase friction pendulum bearing is investigated under totally 60 records developed for multiple level seismic hazard analysis (SLE, DBE and MCE). Mathematical formulations involving complex time history analysis have been proposed for analysis of typical storage tank by multi-phase friction pendulum bearing. Multi-phase friction pendulum bearing represent a new generation of adaptive friction isolation system to control super-structure demand in different hazard levels. This isolator incorporates four concave surfaces and three independent pendulum mechanisms. Pendulum stages can be set to address specific response criteria for moderate, severe and very severe events. The advantages of a Triple Pendulum Bearing for seismic isolation of elevated storage tanks are explored. To study seismic performance of isolated elevated storage tank with multi-phase friction pendulum, analytical simulations were performed with different friction coefficients, pendulum radii and slider displacement capacities.

Design and Implementation of Image Encryption Method for Multi-Parameter Chaotic System (다중변수 혼돈계를 이용한 이미지 암호화 방법의 설계 및 구현)

  • Yim, Geo-Su
    • Convergence Security Journal
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    • v.8 no.3
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    • pp.57-64
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    • 2008
  • The Security of digital images has become increasingly more important in highly computerized and interconnected world. Therefore, The chaos-based encryption algorithms have suggested some new and efficient ways to develop secure image encryption method. This paper is described for the point at issue in all chaos-based encryption method for distribution of a chaotic signals. It has a method for generation of uniformly distributed chaotic signals that we designed secure algorithm of multi-parameter chaotic systems. So we are present validity of the theoretical models for results of image encryption and decryption for proposed method.

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Modal Analysis of Human Leg with Respect to Hip Joint Position by Using Multibody Modeling (다물체 모델링을 통한 Hip Joint 위치에 따른 인체 Leg부의 고유진동특성 분석)

  • NamGoong, Hong;Yoo, Hong-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.8
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    • pp.761-766
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    • 2010
  • The goal of this study is to analysis natural frequency for different static postures of human leg. To perform this research human leg is modeled by multi-body modeling for the musculoskeletal system. This leg model has biarticular muscles which acting on two joints and the muscles represents some of the major muscles, such as hamstring, of the upper and lower limbs. To obtain each static equilibrium position energy method is employed and to analysis natural frequency linearization method for constrained mechanical system is employed. Static equilibrium position depends on some parameter or condition such as hamstring stiffness or external force. Making a change these parameter the aim of this research can be performed.

A Study on the Adaptive Model-Following Control Systems by Slide Mode (슬라이드 모우드를 이용한 모델추종 적응제어에 관한 연구)

  • 천희영;박귀태;권성하;이창훈
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.34 no.10
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    • pp.407-417
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    • 1985
  • This paper describes a new method for the design of adaptive model-following control systems. This design concept is developed using the theory of slide mode. Authors present new results on the sliding control methodology to achieve accurate tracking for a class of multi-input multi-output, time-varying systems in the presence of parameter variations and disturbances. This algorithm can be easily applied to the multivariable control systems and obtained a smoother control signal in comparison to variable structure model following control systems. The design technique is easy and the control structure is simple. The design requires little computational effort. The control system is less sensitive to plant parameter variations and noise disturbances.

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Vibration Suppression Control of Constrained Spatial Flexible Manipulators (구속받는 3차원 유연 매니퓨레이터의 진동억제 제어)

  • 김진수;우찌야마마사루
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.7
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    • pp.189-195
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    • 2000
  • For free motions, vibration suppression of flexible manipulators has been one of the hottest research topics. However, for constrained motions, a little effort has been devoted for vibration suppression control. Using the dependency of elastic deflections of links on contact force under static conditions, vibrations for constrained planar two-link flexible manipulators have been suppressed successfully by controlling the contact force. However, for constrained spatial multi-link flexible manipulators, the vibrations cannot be suppressed by only controlling the contact force. So, the aim of this paper is to clarify the vibration mechanism of a constrained, multi-DOF, flexible manipulator and to devise the suppression method. We apply a concise hybrid position/force control scheme to control a flexible manipulator modeled by lumped-parameter modeling method. Finally, a comparison between simulation and experimental results is presented to show the performance of our method.

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Exact analyses for two kinds of piezoelectric hollow cylinders with graded properties

  • Zhang, Taotao;Shi, Zhifei
    • Smart Structures and Systems
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    • v.6 no.8
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    • pp.975-989
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    • 2010
  • Based on the theory of piezo-elasticity, the paper obtains the exact solutions of functionally graded piezoelectric hollow cylinders with different piezoelectric parameter $g_{31}$. Two kinds of piezoelectric hollow cylinders are considered herein. One is a multi-layered cylinder with different parameter $g_{31}$ in different layers; the other is a continuously graded cylinder with arbitrarily variable $g_{31}$. By using the Airy stress function method with plane strain assumptions, the exact solutions of the mechanic and electrical components of both cylinders are obtained when they are subjected to external voltage (actuator) and pressure (sensor), simultaneously. Furthermore, good agreement is achieved between the theoretical and numerical results, and useful conclusions are given.

Development of an Expert System for Nondestructive Evaluation of Tunnel Lining (터널 라이닝의 비파괴 평가를 위한 전문가시스템 개발)

  • 김문겸;허택녕;이재영;김도훈
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1998.10a
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    • pp.413-420
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    • 1998
  • In this study, an expert system is developed to evaluate a safety of tunnel structures. Using a dynamic finite element analysis module, this expert system predicts dynamic responses of a concrete lining surface which a transient force is applied on and estimates the condition between the concrete lining and surrounding ground. The evaluation parameter values of the module are multi-reflected wave frequency and amplitude of the dynamic responses. The multi-reflected wave frequency represents the depth of concrete lining, and the other parameter, the amplitude of the frequency, is utilized for detecting the internal flaws. A comparison of the dynamic responses between numerical and experimental model test verifies an effectiveness of this system. By this expert system, the safety of tunnel structures and the detection of internal flaws of concrete linings are estimated quantitatively.

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