• Journal of Power Electronics
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• 제7권4호
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• pp.310-317
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• 2007

In this paper, an analysis and hysteretic controller design of a $3^{rd}$ order buck converter is presented. The proposed hysteretic controller consists of an inner current-loop, just like the conventional cascade control scheme, and an outer voltage-loop for load voltage regulation. Although it is possible to include an inner current loop from different branches of the converter, from the feasibility and operational point of view, the load side capacitor current would be the better choice. The addition of an inner current-loop improves the dynamic performance of the converter while preserving the robustness of the hysteretic control. The controller formulation and closed-loop converter performance analysis are validated through computer simulations. Few experimental results of the proposed converter are given and compared with the buck converter.

• 한국공간구조학회논문집
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• 제20권1호
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• pp.79-86
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• 2020

The performance enhancement of various damping systems from natural hazards has become an highly important issue in engineering field. In this paper, ENTA hysteretic dampers were tested under cyclic loadings to evaluate their performance in terms of ductility and energy dissipation. The test results showed that the hysteretic dampers are effective damping systems to enhance the buildings performance for remodeling and retrofit of buildings. Also, the hysteretic dampers were modeled in FEM(Finite Element Method) structural analysis program. As comparing the computer modeling and the experiment, this study model reflects the nonlinear behavior of steel and derives the hysteresis loop.

• Structural Engineering and Mechanics
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• 제76권1호
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• pp.101-114
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• 2020

In this paper, an improved experience-based learning algorithm (EBL), termed as IEBL, is proposed to solve the nonlinear hysteretic parameter identification problem with Bouc-Wen model. A quasi-opposition-based learning mechanism and new updating equations are introduced to improve both the exploration and exploitation abilities of the algorithm. Numerical studies on a single-degree-of-freedom system without/with viscous damping are conducted to investigate the efficiency and robustness of the proposed algorithm. A laboratory test of seven lead-filled steel tube dampers is presented and their hysteretic parameters are also successfully identified with normalized mean square error values less than 2.97%. Both numerical and laboratory results confirm that, in comparison with EBL, CMFOA, SSA, and Jaya, the IEBL is superior in nonlinear hysteretic parameter identification in terms of convergence and accuracy even under measurement noise.

• Journal of Advanced Marine Engineering and Technology
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• 제27권3호
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• pp.421-428
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• 2003

The aerodynamic characteristics of the Wells turbine for wave energy conversion have been investigated by the numerical simulation to reproduce hysteretic behaviors. The pressure distributions on the suction surface of the blade were investigated to find out the cause of the hysteretic mechanism. The results have shown that the hysteretic behavior is associated with streamwise vertical flow appearing near the suction surface and become more obvious. as the tip clearance and solidity change. Also it has shown that such phenomena occur due to different behaviors of wakes in the accelerating and decelerating flow process. The CFD analysis shows a good agreement with experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.257-262
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• 2003

Base isolation bearings are known as an effective system to Protect bridges from the earthquake damage. There are many types of base isolation bearings in the market. Among them, steel hysteretic damper, made of mild steel and one of the oldest ones, has some good features. Since steel hysteretic damper is made of steel and has simple structure, it is cheeper and easier to maintain than other types. Despite the advantages, steel hysteretic damper with pin-type elements has no application in Korea. The steel hysteretic damper with pin-type elements are tested to examin the basic characteristics and to evaluate antiseismic performance. In this paper, the results of the test are presented.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.331-345
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• 2011

In this paper, a visco-hysteretic vibration absorber (VA) is proposed to increase the flutter speed of an airfoil and enhance damping in the pre- and post-flutter regimes. The passive system consists of a parallel arrangement of a dashpot and a rateindependent hysteretic element, represented by the Bouc-Wen differential model. The equations of motion are obtained and various tools of linear and nonlinear dynamics are employed to study the effects of the visco-hysteretic VA in the pre- and postflutter ranges.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.19-26
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• 1999

This paper describes an analytical study on nonlinear hysteretic behavior of hybrid steel beam with reinforced concrete ends. Two types of analytical model, Polygonal Model[PM] and Hybrid Model[HM], were used to represent the nonlinear hysteretic behavior PM used three parameters, HM used an additional parameter to consider the initial stiffness reduction. The parameters calibrated comparing the hysteretic performance obtained from experiments. The purpose of this study is to develop an analytical model which can take into account the initial stiffness reduction of the hybrid members and to represent exactly the hysteretic performance for the hybrid structures with RC and steel. The analytical study showed PM tends to overestimate initial stiffness and strength. However, HM which is capable to consider the initial stiffness reduction gave good prediction on initial stiffness, post-yielding performance, strength, pinching response and so on.

• 전산구조공학
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• 제4권1호
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• pp.133-142
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• 1991

지진하중과 유사한 반복하중에 의한 철근 콘크리트 부재의 실제 거동을 재생키 위한 해석적인 이력모델을 제시하였다. 특히 RC부재의 동적거동의 중요한 현상들인 강성저하, 강도저하 그리고 전단영향등의 해석 모델을 소개하였으며 제안된 이력모델의 정확성 및 사용성등의 평가를 위하여 실험결과의 하중-변위 곡선들과 비교 분석하였다.

• Structural Engineering and Mechanics
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• 제55권1호
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• pp.205-228
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• 2015

The results of a numerical investigation pertaining to the hysteretic behaviour of concrete filled steel tubular (CFT) column to I-beam connections are discussed in detail. Following the verification of the numerical results against the available experimental tests, the nonlinear finite element (FE) analysis was implemented to evaluate the effects of different parameters including the column axial load, beam lateral support, shape and arrangement of stiffeners, stiffness of T-stiffeners, and the number of shear stiffeners. Pursuing this objective, an external CFT column to beam connection, tested previously, was selected as the case-study. The lateral forces on the structure were simulated, albeit approximately, using an incremental cyclic loading reversal applied at the beam tip. The results were compared in terms of hysteretic load-displacement curves, stress distributions in connection, strength, rotation, and energy dissipation capacity. It was shown that external T-stiffeners combined with internal shear stiffeners play an important role in the hysteretic performance of CFT columns to I-beam connections.

• Structural Engineering and Mechanics
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• 제23권2호
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• pp.177-193
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• 2006

Determining the hysteretic energy demand and dissipation capacity and level of damage of the structure to a predefined earthquake ground motion is a highly non-linear problem and is one of the questions involved in predicting the structure's response for low-performance levels (life safe, near collapse, collapse) in performance-based earthquake resistant design. Neural Network (NN) analysis offers an alternative approach for investigation of non-linear relationships in engineering problems. The results of NN yield a more realistic and accurate prediction. A NN model can help the engineer to predict the seismic performance of the structure and to design the structural elements, even when there is not adequate information at the early stages of the design process. The principal aim of this study is to develop and test multi-layered feedforward NNs trained with the back-propagation algorithm to model the non-linear relationship between the structural and ground motion parameters and the hysteretic energy demand in steel moment resisting frames. The approach adapted in this study was shown to be capable of providing accurate estimates of hysteretic energy demand by using the six design parameters.