• Title, Summary, Keyword: dynamic response

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Dynamic reliability analysis of offshore wind turbine support structure under earthquake

  • Kim, Dong-Hyawn;Lee, Gee-Nam;Lee, Yongjei;Lee, Il-Keun
    • Wind and Structures
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    • v.21 no.6
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    • pp.609-623
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    • 2015
  • Seismic reliability analysis of a jacket-type support structure for an offshore wind turbine was performed. When defining the limit state function by using the dynamic response of the support structure, a number of dynamic calculations must be performed in a First-Order Reliability Method (FORM). That means analysis costs become too high. In this paper, a new reliability analysis approach using a static response is used. The dynamic effect of the response is considered by introducing a new parameter called the Peak Response Factor (PRF). The probability distribution of PRF can be estimated by using the peak value in the dynamic response. The probability distribution of the PRF was obtained by analyzing dynamic responses during a set of ground motions. A numerical example is presented to compare the proposed approach with the conventional static response-based approach.

Analysis of the Reduction of the Dynamic Response for the CNC 5 Axles Machining Center (CNC 5축 공작기계의 동응답 저감 해석)

  • KIM, Gi Man;CHOI, Seong Dae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.9 no.5
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    • pp.83-89
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    • 2010
  • In this paper, the dynamic response of a CNC 5 Axles machining center was analyzed and then controlled passively by using the dynamic absorber. For the simplification of the theoretical approach, the CNC 5 Axles machining center was modeled as a flexible beam(Bed) having a point mass(Column), two discrete systems(a Table-set and a dynamic absorber). Specifically by using the dynamic absorber, the dynamic response of a Table-set which be caused by the vibration of a flexible beam, was reduced down to the infinitesimal level. The optimal design factors of the dynamic absorber were obtained from the minimization of the cost function. It was found that the natural frequencies of a UT-380 machining center be varied due to the movement of the Table-set. In view of the dynamic response of a Table-set, the larger spring stiffness and mass of the dynamic absorber were found to give the greater reduction.

A Dynamic Calibration Technique for Piezoelectric Sensors Using Negative Going Dynamic Pressure (부방향 동압력을 이용한 압전형 압력센서의 교정기법)

  • Kim, Eung-Su
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.4
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    • pp.491-499
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    • 2009
  • The determination of response characteristics for pressure sensors is routinely limited to static calibration against a deadweight pressure standard. The strength of this method is that the deadweight device is a primary standard used to generate precise pressure. Its weakness lies in the assumption that the static and dynamic responses of the sensor in question are equivalent. Differences in sensor response to static and dynamic events, however, can lead to serious measurement errors. Dynamic techniques are required to calibrate pressure sensors measuring dynamic events in milliseconds. In this paper, a dynamic calibration using negative going dynamic pressure is proposed to determine dynamic pressure response for piezoelectric sensors. Sensitivity and linearity of sensor by the dynamic calibration were compared with those by the static calibration. The uncertainty of calibration results and the goodness of fit test of linear regression analysis were presented. The results show that the dynamic calibration is applicable to determine dynamic pressure response for piezoelectric sensors.

On the absolute maximum dynamic response of a beam subjected to a moving mass

  • Lotfollahi-Yaghin, Mohammad Ali;Kafshgarkolaei, Hassan Jafarian;Allahyari, Hamed;Ghazvini, Taher
    • Structural Engineering and Mechanics
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    • v.54 no.1
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    • pp.55-67
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    • 2015
  • Taking the mid-span/center-point of the structure as the reference point of capturing the maximum dynamic response is very customary in the available literature of the moving load problems. In this article, the absolute maximum dynamic response of an Euler-Bernoulli beam subjected to a moving mass is widely investigated for various boundary conditions of the base beam. The response of the beam is obtained by utilizing a robust numerical method so-called OPSEM (Orthonormal Polynomial Series Expansion Method). It is underlined that the absolute maximum dynamic response of the beam does not necessarily take place at the mid-span of the beam and thus the conventional analysis needs modifications. Therefore, a comprehensive parametric survey of the base beam absolute maximum dynamic response is represented in which the contribution of the velocity and weight of the moving inertial objects are scrutinized and compared to the conventional version (maximum at mid-span).

A new metric for LCD temporal response;Dynamic gamma

  • Pan, Hao;Feng, Xiaofan;Daly, Scott
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.419-422
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    • 2004
  • In this paper, we propose a new metric called "dynamic gamma" to quantitatively evaluate the dynamic temporal response of an LC display device. The widely-used response time and corresponding 3-D bar graphs cannot fully describe the dynamic characteristics of an LC panel [1], and using response time to compare different LC panels and assessing the dynamic features of LC panels is difficult. On the other hand, the new metric MPRT mixes an LC panel's slow temporal response with its hold-type display effect. The proposed new metric, dynamic gamma, and corresponding 2-D plots, are arguably more suitable for quantitatively characterizing the dynamic characteristics of an LC panel, so comparing two LC panels becomes easy. Furthermore, dynamic gamma has the unique property that it can be used to quantify the limitations/capabilities and to assess the effectiveness of an overdrive mechanism for a particular LCD. In the paper, two LC panels using different technology are analyzed and compared using this new metric.

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Dynamic bending response of SWCNT reinforced composite plates subjected to hygro-thermo-mechanical loading

  • Chavan, Shivaji G.;Lal, Achchhe
    • Computers and Concrete
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    • v.20 no.2
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    • pp.229-246
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    • 2017
  • The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

Study on Implementing Dynamic Pricing to Demand Response System (변동요금제 기반의 DR 프로그램 운영 방안 연구)

  • Yu, In-Hyeob
    • Proceedings of the KIEE Conference
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    • pp.541_542
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    • 2009
  • This paper reviews the definition and background of dynamic pricing which is the essential element of demand response system. Also, economic efficiency and related issues on dynamic pricing are studied. Several issues on design and operation of demand response system, which can implement the dynamic pricing, are described. Therefore the results will be helpful for developing the demand response system with dynamic pricing.

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Effect of vehicle flexibility on the vibratory response of bridge

  • Lalthlamuana, R.;Talukdar, Sudip
    • Coupled systems mechanics
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    • v.3 no.2
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    • pp.147-170
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    • 2014
  • In the recent times, dimensions of heavy load carrying vehicle have changed significantly incorporating structural flexibility in vehicle body. The present paper outlines a procedure for the estimation of bridge response statistics considering structural bending modes of the vehicle. Bridge deck roughness has been considered to be non homogeneous random process in space. Influence of pre cambering of bridge surface and settlement of approach slab on the dynamic behavior of the bridge has been studied. A parametric study considering vehicle axle spacing, mass, speed, vehicle flexibility, deck unevenness and eccentricity of vehicle path have been conducted. Dynamic amplification factor (DAF) of the bridge response has been obtained for several of combination of bridge-vehicle parameters. The present study reveals that flexible modes of vehicle can reduce dynamic response of the bridge to the extent of 30-37% of that caused by rigid vehicle model. However, sudden change in the bridge surface profile leads to significant amount of increment in the bridge dynamic response even if flexible bending modes remain active. The eccentricity of vehicle path and flexural/torsional rigidity ratios plays a significant role in dynamic amplification of bridge response.

Dynamic response Analysis of Rockfill Dam (필댐의 지진응답 해석)

  • 이종욱
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.113-120
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    • 1999
  • When we design the large rockfill dams the safety of dams against the quake must be considered. Generally pseudostatic analysis method has been used for slope stability and evaluation of safety but the case of dynamic response analysis of earthquake was not in general in Korea. Therefore we need to perform the dynamic response analysis of rockfill dams from these results we analyze the dynamic behavior of dam body such as response displacement and response acceleration. consequently we analyse the selected model of rockfill dam using the FLAC-2D (FDM) program.

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