• Title/Summary/Keyword: ratio-dependent

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Amplitude dependent damping ratio of domestic tall building by RD method (국내 고층건물의 RD법에 의한 감쇠율의 진폭의존성)

  • Yoon, Sung-Won
    • 한국공간정보시스템학회:학술대회논문집
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    • 2004.05a
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    • pp.89-95
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    • 2004
  • The measured damping ratio was analysed to obtain amplitude dependence. Wind-induced vibration of 20 story steel-framed building was measured to investigate amplitude dependence by RD method. Micro-tremo vibrations of 20 RC bearing wall typed buildings were performed to analysis the amplitude dependence by formula proposed by Tamua and ESDU. Amplitude dependent damping in 17 story steel-framed building was showed clearly in the increasing rate of 9%. But Amplitude dependent damping of 17 RC bearing wall typed buildings was very low in the increasing rate of 2.5%. The tendency of dynamic properties of building obtained here are useful for the validation of dynamic properties of buildings in the evaluation of serviceability.

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DYNAMICS OF A DISCRETE RATIO-DEPENDENT PREDATOR-PREY SYSTEM INCORPORATING HARVESTING

  • BAEK, HUNKI;HA, JUNSOO;HYUN, DAGYEONG;LEE, SANGMIN;PARK, SUNGJIN;SUH, JEONGWOOK
    • East Asian mathematical journal
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    • v.31 no.5
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    • pp.743-751
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    • 2015
  • In this paper, we consider a discrete ratio-dependent predator-prey system with harvesting effect. In order to investigate dynamical behaviors of this system, first we find out all fixed points of the system and then classify their stabilities by using their Jacobian matrices and local stability method. Next, we display some numerical examples to substantiate theoretical results and finally, we show numerically, by means of a bifurcation diagram, that various dynamical behaviors including cycles, periodic doubling bifurcation and chaotic bands can be existed.

Effects of frequency ratio on bridge aerodynamics determined by free-decay sectional model tests

  • Qin, X.R.;Kwok, K.C.S.;Fok, C.H.;Hitchcock, P.A.
    • Wind and Structures
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    • v.12 no.5
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    • pp.413-424
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    • 2009
  • A series of wind tunnel free-decay sectional model dynamic tests were conducted to examine the effects of torsional-to-vertical natural frequency ratio of 2DOF bridge dynamic systems on the aerodynamic and dynamic properties of bridge decks. The natural frequency ratios tested were around 2.2:1 and 1.2:1 respectively, with the fundamental vertical natural frequency of the system held constant for all the tests. Three 2.9 m long twin-deck bridge sectional models, with a zero, 16% (intermediate gap) and 35% (large gap) gap-to-width ratio, respectively, were tested to determine whether the effects of frequency ratio are dependent on bridge deck cross-section shapes. The results of wind tunnel tests suggest that for the model with a zero gap-width, a model to approximate a thin flat plate, the flutter derivatives, and consequently the aerodynamic forces, are relatively independent of the torsional-to-vertical frequency ratio for a relatively large range of reduced wind velocities, while for the models with an intermediate gap-width (around 16%) and a large gap-width (around 35%), some of the flutter derivatives, and therefore the aerodynamic forces, are evidently dependent on the frequency ratio for most of the tested reduced velocities. A comparison of the modal damping ratios also suggests that the torsional damping ratio is much more sensitive to the frequency ratio, especially for the two models with nonzero gap (16% and 35% gap-width). The test results clearly show that the effects of the frequency ratio on the flutter derivatives and the aerodynamic forces were dependent on the aerodynamic cross-section shape of the bridge deck.

An Experimental Study on Performance Evaluation of Hysteretic Steel Slit Damper (슬릿형 강재이력 감쇠장치의 성능평가를 위한 실험연구)

  • Choi, Ki-Sun;Lee, Hyun-Jee;Kim, Min-Sun;You, Young-Chan
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.1
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    • pp.33-39
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    • 2018
  • This study performed experimental validation of the hysteretic steel slit damper's basic and dependent characteristics, which should be considered for the design. The basic characteristic of the steel slit damper is used for determining design properties of non-linear analysis, such as yielding strength, yielding displacement, elastic stiffness and post-yielding stiffness. In order to evaluate dependent characteristics of the hysteretic steel slit damper, repeated deformation capacity with respect to the displacement, velocity and aspect ratio of the damper was evaluated. In this study, steel slit damper, which is widely used in Korea, was considered. The slit dampers with 55kN and 240kN of yielding strength were produced and tested. It was concluded that the slit damper's hysteresis behavior was affected by the dependent characteristics: displacement, velocity and aspect ratio. In other words, the steel slit damper's behavior was stable within limit displacement, and aspect ratio of the strut affected repeated deformation capacity of the damper subjected to large deformation. In addition, it was observed that the repeated deformation capacity abruptly decreased at the high speed range (${\geq}60mm/sec$). Furthermore, the experimental results were evaluated with the criterion of the damping device specified in ASCE7-10.

Effect of Stress-Dependent Modulus and Poisson's Ratio on Rutting Prediction in Unbound Pavement Foundations (도로기초의 Rutting 예측에 미치는 응력의존 탄성계수와 포와송비의 영향)

  • Park, Seong-Wan
    • Journal of the Korean Geotechnical Society
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    • v.23 no.3
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    • pp.15-24
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    • 2007
  • This paper will present a simple approach (or predicting layer deformation of unbound pavement materials with stress-dependent material properties. The approach is based on an uncoupled formulation in which the resilient and deformation response of unbound materials are considered separately. As a result, an uncoupled approach incorporating a resilient stiffness and Poisson's ratio model is able to simulate field measured deformation in pavement foundations. In addition, a sensitivity analysis is conducted to identify the significant factors in the stress-dependent modulus and Poison's ratio model. The predicted trends of deformation from this analysis are presented and discussed.

DYNAMIC ANALYSIS OF A MODIFIED STOCHASTIC PREDATOR-PREY SYSTEM WITH GENERAL RATIO-DEPENDENT FUNCTIONAL RESPONSE

  • Yang, Yu;Zhang, Tonghua
    • Bulletin of the Korean Mathematical Society
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    • v.53 no.1
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    • pp.103-117
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    • 2016
  • Abstract. In this paper, we study a modified stochastic predator-prey system with general ratio-dependent functional response. We prove that the system has a unique positive solution for given positive initial value. Then we investigate the persistence and extinction of this stochastic system. At the end, we give some numerical simulations, which support our theoretical conclusions well.

DYNAMICS OF A RATIO-DEPENDENT PREY-PREDATOR SYSTEM WITH SELECTIVE HARVESTING OF PREDATOR SPECIES

  • Kar Tapan Kumar
    • Journal of applied mathematics & informatics
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    • v.23 no.1_2
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    • pp.385-395
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    • 2007
  • The dynamics of a prey-predator system, where predator population has two stages, juvenile and adult with harvesting are modelled by a system of delay differential equation. Our analysis shows that, both the delay and harvesting effort may play a significant role on the stability of the system. Numerical simulations are given to illustrate the results.

ASYMPTOTICAL BEHAVIORS OF A DIFFUSIVE PREDATOR-PREY SYSTEM WITH RATIO-DEPENDENT FUNCTIONAL RESPONSE AND MATURATION DELAY

  • Wonlyul Ko
    • Journal of the Chungcheong Mathematical Society
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    • v.36 no.1
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    • pp.39-53
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    • 2023
  • In this paper, we consider a delayed ratio-dependent predator-prey reaction-diffusion system with homogenous Neumann boundary conditions. We study the existence of nonnegative solutions and the stability of the nonnegative equilibria to the system. In particular, we provide a sufficient condition for the positive equilibrium to be globally asymptotically stable.

A Study on Transition From Cycle-dependent to Time-dependent Crack Growth in SUS304 Stainless Steel (SUS304강의 사이클의존형에서 시간의존형균열성장으로의 천이에 관한 연구)

  • 주원식;조석수
    • Journal of Welding and Joining
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    • v.14 no.1
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    • pp.38-46
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    • 1996
  • High temperature low cycle fatigue crack growth behavior is investigated over a range of two temperatures and various frequencies in SUS 304 stainless steel. It is found that low frequency and temperature can enhance time-dependent crack growth. With high temperature, low frequency and long crack length, ${\Delta}J_c/{\Delta}J_ f$, the ratio of creep J integral range to fatigue J integral range is increased and time-dependent crack growth is accelerated. Interaction between ${\Delta}J_f$ and ${\Delta}J_c$ is occured at high frequency and low temparature and ${\Delta}J_c$, creep J integral range is fracture mechanical parameter on transition from cycle-dependent to time dependent crack growth in creep temperature region.

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Removal of Aspect-Ratio-Dependent Etching by Low-Angle Forward Reflected Neutral-Beam Etching (Low-Angle Forward Reflected Neutral Beam Etching을 이용한 Aspect-Ratio-Dependent Etching 현상의 제거)

  • Min Kyung-Seok;Park Byoung-Jae;Yeom Geun-Young;Kim Sung-Jin;Lee Jae-Koo
    • Journal of the Korean Vacuum Society
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    • v.15 no.4
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    • pp.387-394
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    • 2006
  • In this study, the effect of using a neutral beam formed by low-angle forward reflection of a reactive ion beam on aspect-ratio-dependent etching (ARDE) has been investigated. When a SF6 Inductively Coupled Plasma and $SF_6$ ion beam etching are used to etch poly-Si, ARDE is observed and the etching of poly-Si on $SiO_2$ shows a higher ARDE effect than the etching of poly-Si on Si. However, by using neutral beam etching with neutral beam directionality higher than 70 %, ARDE during poly-Si etching by $SF_6$ can be effectively removed, regardless of the sample conditions. The mechanism for the removal of ARDE via a directional neutral beam has been demonstrated through a computer simulation of different nanoscale features by using the two-dimensional XOOPIC code and the TRIM code.