• 제목/요약/키워드: Dynamic models

검색결과 2,871건 처리시간 0.029초

Analysis of the Static and Dynamic Stability Properties of the Unmaned Airship

  • Lee, Hae Chang
    • International Journal of Aeronautical and Space Sciences
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    • 제2권2호
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    • pp.82-94
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    • 2001
  • The purpose of this paper is to analyze the static and dynamic stability-of the unmanned airship under development ; the target airship's over-all length of hull is 50m and the maximum diameter is 12.5m. For the analysis, the dynamic model of an airship was defined and both the nonlinear and linear dynamic equations of motion were derived. Two different configuration models (KA002Y and KA003Y) of the airship were used for the target model of the static stability analysis and the dynamic stability analysis. From the result of analyses, though the airship is unstable in static stability, dynamic characteristics of the airship can provide the stable dynamic stability. All of the results, airship models and dynamic flight equations will be an important basement and basic information for the next step of developing the automatic flight control system(AFCS) and the stability augmentation system(SAS) for the unmanned airship as well as for the stratospheric airship in the future.

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Dynamic Heterogeneity in Spin Facilitated Model of Supercooled Liquid: Crossover from Fragile to Strong Liquid Behavior

  • Choi, Seo Woo;Kim, Soree;Jung, YounJoon
    • EDISON SW 활용 경진대회 논문집
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    • 제3회(2014년)
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    • pp.183-195
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    • 2014
  • Kinetically constrained models (KCM) have attracted interest as models that assign dynamic origins to the interesting dynamic properties of supercooled liquid. Signs of dynamic heterogeneity in the crossover model that linearly interpolates between the FA-like symmetric constraint and the East model constraint by asymmetric parameter b were investigated using Monte Carlo technique. When the asymmetry parameter was decreased sufficiently, smooth fragile-to-strong dynamic transition was observed in terms of the relaxation time, diffusion constant, Stokes-Einstein violation, and dynamic length scale. Competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism is behind such transition.

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구조물과 부계통간의 연계방법에 따른 지진응답 분석 (Analysis of Seismic Response due to the Dynamic Coupling Between a Primary Structure and Secondary System)

  • 정광섭;곽신영;최인길;임승현
    • 한국지진공학회논문집
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    • 제24권2호
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    • pp.87-93
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    • 2020
  • Seismic responses due to the dynamic coupling between a primary structure and secondary system connected to a structure are analyzed in this study. The seismic responses are compared based on dynamic coupling criteria and according to the error level in the natural frequency, with the recent criteria being reliant on the error level in the spectral displacement response. The acceleration responses and relative displacement responses of a primary structure and a secondary system for a coupled model and two different decoupled models of two degrees-of-freedom system are calculated by means of the time integration method. Errors in seismic responses of the uncoupled models are reduced with the recent criteria. As the natural frequency of the secondary system increases, error in the natural frequency decreases, but seismic responses of uncoupled models can be underestimated compared to that of coupled model. Results in this paper can help determine dynamic coupling and predict uncoupled models' response conservatism.

자동차 $CO_2$ 냉방시스템의 동적모델과 지능제어알고리즘 (Dynamic Models and Intelligent Control Algorithms for a $CO_2$ Automotive Air Conditioning System)

  • 한도영;장경창
    • 한국자동차공학회논문집
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    • 제14권4호
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    • pp.49-58
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    • 2006
  • In the respect of the environmental protection viewpoint, $CO_2$ may be one of the most attractive alternative refrigerants for an automotive air-conditioning system. For the development of control algorithm of a $CO_2$ automotive air-conditioning system, characteristics of a $CO_2$ refrigerant should be considered. The high-side pressure of a $CO_2$ system should be controlled in order to improve the system efficiency. In this study, dynamic physical models of a $CO_2$ system were developed and dynamic behaviors of the system were predicted by using these models. Control algorithms of a $CO_2$ system were also developed and the effectiveness of these algorithm was verified by using dynamic models.

선박 조종 시뮬레이션을 위한 단순 기동 모델 개발 (Development of Simple Dynamic Models for Ship Manoeuvring Simulation)

  • 김동진;여동진;이기표
    • 한국시뮬레이션학회논문지
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    • 제19권3호
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    • pp.17-25
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    • 2010
  • 선박 조종 시뮬레이션을 구성하는 기동 모델은 대상 선박의 동역학적인 특성을 현실에 가깝게 구현해야 하며, 신속한 계산 및 결과 처리가 가능하여야 한다. 다중 선박을 대상으로 하는 실시간 조종 시뮬레이션에서는 계산 시간 단축을 위해 일반적으로 선회각이나 선회율, 또는 전진 속도에 대한 1차 미분방정식 모델을 사용하여 선박의 움직임을 구현하게 된다. 본 논문에서는 대상 선박의 선회 시험 정보가 주어져 있을 경우 이를 이용한 선박의 단순 기동 모델링 및 계수 추정법을 제안하였다. 전진속도가 일정한 모델과 전진 속도의 변화를 고려한 모델의 계수 추정법을 수학적으로 전개하였으며, 실선 선회 시험 자료를 이용하여 제안된 모델의 유용성을 검증하였다.

Flutter analysis by refined 1D dynamic stiffness elements and doublet lattice method

  • Pagani, Alfonso;Petrolo, Marco;Carrera, Erasmo
    • Advances in aircraft and spacecraft science
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    • 제1권3호
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    • pp.291-310
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    • 2014
  • An advanced model for the linear flutter analysis is introduced in this paper. Higher-order beam structural models are developed by using the Carrera Unified Formulation, which allows for the straightforward implementation of arbitrarily rich displacement fields without the need of a-priori kinematic assumptions. The strong form of the principle of virtual displacements is used to obtain the equations of motion and the natural boundary conditions for beams in free vibration. An exact dynamic stiffness matrix is then developed by relating the amplitudes of harmonically varying loads to those of the responses. The resulting dynamic stiffness matrix is used with particular reference to the Wittrick-Williams algorithm to carry out free vibration analyses. According to the doublet lattice method, the natural mode shapes are subsequently used as generalized motions for the generation of the unsteady aerodynamic generalized forces. Finally, the g-method is used to conduct flutter analyses of both isotropic and laminated composite lifting surfaces. The obtained results perfectly match those from 1D and 2D finite elements and those from experimental analyses. It can be stated that refined beam models are compulsory to deal with the flutter analysis of wing models whereas classical and lower-order models (up to the second-order) are not able to detect those flutter conditions that are characterized by bending-torsion couplings.

Dynamic analysis of frames with viscoelastic dampers: a comparison of damper models

  • Lewandowski, R.;Bartkowiak, A.;Maciejewski, H.
    • Structural Engineering and Mechanics
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    • 제41권1호
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    • pp.113-137
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    • 2012
  • Frame structures with viscoelastic (VE) dampers mounted on them are considered in this paper. It is the aim of this paper to compare the dynamic characteristics of frame structures with VE dampers when the dampers are modelled by means of different models. The classical rheological models, the model with the fractional order derivative, and the complex modulus model are used. A relatively large structure with VE dampers is considered in order to make the results of comparison more representative. The formulae for dissipation energy are derived. The finite element method is used to derive the equations of motion of the structure with dampers and such equations are written in terms of both physical and state-space variables. The solution to motion equations in the frequency domain is given and the dynamic properties of the structure with VE dampers are determined as a solution to the appropriately defined eigenvalue problem. Several conclusions concerning the applicability of a family of models of VE dampers are formulated on the basis of results of an extensive numerical analysis.

착석자세 인체의 상하/전후/피치 가진 시험 (Experiment for Seated Human Body to Vertical/Fore-and-aft/Pitch Excitation)

  • 김종완;김기선;김광준
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2009년도 추계학술대회 논문집
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    • pp.656-660
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    • 2009
  • Various dynamic models of seated posture human body have been developed because the importance about the ride comfort assessment of vehicles is highly emphasized from day to day. The dynamic models of human body make possible the simulation of ride comfort assessment by applied to the vehicle dynamic model. Recently, the importance of ride comfort is also regarded to working vehicles such as excavators and the research of the ride comfort assessment for working vehicle is required. Only vertical vibration dominantly occurs on the seat of the private car driving with constant velocity. In contrast, vertical/fore-and-aft/pitch vibration seriously occurs on the seat of the working excavator. So, the dynamic models of seated human body applied to working vehicles should describe the dynamic characteristics for vertical/fore-and-aft/pitch direction. In this paper, the dynamic characteristics of seated human body are represented as apparent inertia matrix. The apparent inertia matrix is obtained by the vertical/fore-and-aft/pitch excitation of seated human body. 6 resonance frequencies are observed in apparent inertia matrix. This result can be applied to develop the dynamic model for seated posture human body.

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자기부상열차 모듈의 동특성 시뮬레이션 (Dynamic Simulation for Modules of a Magnetically-Levitated Vehicle)

  • 김종문
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제55권12호
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    • pp.653-660
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    • 2006
  • In this paper, dynamic simulation results for modules of a magnetically-levitated(Maglev) vehicle are presented. The mathematical dynamic models for the Maglev vehicle are firstly derived. The Maglev system consists of one vehicle, two half-bogies, one guideway, four secondary suspensions, eight electromagnets and levitation control systems. Also, the dynamic characteristics are analysed by using the derived models. Finally, two simulations such as reference airgap step change of 1mm and rail step change of 1mm, are carried out. The dynamic simulation results are shown to testify the developed dynamic simulation program. From the results, we can see the possibility of the dynamic simulation program to develop a new Maglev vehicle system.

차량 모델의 복잡성이 차량동력학 해석에 미치는 영향 : 모델의 비교 및 검증 (An Effect of the Complexity in Vehicle Dynamic Models on the Analysis of Vehicle Dynamic Behaviors: Model Comparison and Validation)

  • 배상우;윤중락;이장무;탁태오
    • 한국자동차공학회논문집
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    • 제8권6호
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    • pp.267-278
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    • 2000
  • Vehicle dynamic models in handing and stability analysis are divided into three groups: bicycle model, roll axis model and full vehicle model. Bicycle model is a simple linear model, which hag two wheels with load transfer being ignored. Roll axis model treats left and right wheels independently. In this model, load transfer has a great effect on nonlinearity of tire model. Effects of suspension system can be analyzed by using full vehicle model, which is included suspension stroke motions. In this paper, these models are validated and compared through comparison with road test, and the effects of suspension kinematics and compliance characteristics on vehicle motion are analyzed. In handling and stability analysis, roll axis model can simulate the real vehicle motion more accurately than full vehicle model. Compliance steer has a significant effect, but the effect of suspension kinematics is negligible.

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