• 한국안전학회지
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• 제8권1호
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• pp.80-87
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• 1993

본 논문은 에너지 분산 장치의 일종인 점탄성 감쇠기를 설치한 건물의 거동에 관한 실험 및 해석적 연구를 다루고자 한다. 지진 모형 실험 장치를 이용하여 감쇠기를 설치한 건물의 구조응답을 구하고. 이를 감쇠기를 설치하지 않은 건물에 대하여 행해진 비탄성 해석 결과와 비교한다. 결론적으로 말하면. 점탄성 감쇠기는 강지진 하중에 의하여 건물에 발생한 과도한 진동을 감소시키는데 효과적이다 일반적으로 점탄성 감쇠기를 건물에 설치함으로써 감쇠비와 함께 강성도가 증가하여 지진 응답을 감소시키는데 기여하나, 대부분은 감쇠기의 역할에 의해 증가된 감쇠비의 영향인 것으로 밝혀졌다. 모드 변형에너지법을 이용하여 감쇠기에 의해 증가된 등가구조 감쇠를 성공적으로 예측할 수 있으며 따라서 점탄성 감쇠기를 설치한 건물의 지진 응답이 일반적인 모드 해석 기법을 이용한 수치모형해석에 의해 정확히 예측된다.

• Journal of Mechanical Science and Technology
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• 제15권2호
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• pp.199-209
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• 2001

Modal analysis method (MAM) is introduced for the fully coupled structural dynamic problems. In this paper, the beam with active constrained layered damping (ACLD) treatment is considered as a representative problem. The ACLD beam consists of a viscoelastic layer that is sandwiched between the base beam structure and an active piezoelectric layer. The exact damped natural modes are spectrally formulated from a set of fully coupled dynamic equations of motion. The orthogonality property of the exact damped natural modes is then derived in a closed form to complete the modal analysis method. The accuracy of the present MAM is evaluated through some illustrative examples: the dynamic characteristics obtained by the present MAM are compared with the results by spectral element method (SEM) and finite element method (FEM). It is numerically proved that MAM solutions become identical to the accurate SEM solutions as the number of exact natural used in MAM is increased.

• 한국생산제조학회지
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• 제25권1호
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• pp.75-82
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• 2016

In this study, a cross-damped low vibration controller was developed to reduce vibration in ultra-precision dual stage driven by master/slave principle. In master-slave structure, the master stage leads the driving motion and the slave stage follows it so as to maintain a constant gap between two stages. In this structure, a small perturbation of master stage makes big oscillations in slave servoing stage, so a low damped master stage composed of voice coil motor makes a long vibration in settling area after driving motion profile. In this research, an effective feedback damping algorithm for increase the damping characteristics of the dual stage was developed. The designed velocity damping algorithm improves the system stability and reduces the settling time of the whole system. Simulation and experimental results show that the developed algorithm reduces settling time and improves the regulating performance.

• 대한토목학회논문집
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• 제13권2호
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• pp.111-120
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• 1993

본 논문은 에너지 분산 장치의 일종인 점탄성 감쇠기를 설치한 건물의 거동에 관한 실험 및 해석적 연구이다. 점탄성 감쇠기는 강지진 하중에 의하여 건물에 발생한 과도한 진동을 감소시키는데 효과적이다, 모드 변형에너지법을 이용하여 감쇠기에 의해 증가된 등가구조감쇠를 성공적으로 예측할 수 있으며, 따라서 점탄성 감쇠기를 설치한 건물의 지진 응답이 일반적인 모드 해석기법을 이용한 수치 모형 해석에 의해 정확히 예측된다. 이러한 결과를 토대로, 점탄성 감쇠기를 설치한 건물에 대한 설계 방법을 제시한다. 이 설계 방법은 일반적인 건물의 설계에 감쇠비라는 설계 요소를 추가함으로써 가능해진다.

• Structural Engineering and Mechanics
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• 제75권6호
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• pp.713-722
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• 2020

This article aims to illustrate the damped dynamic responses of layered functionally graded (FG) thick 2D beam under dynamic pulse sinusoidal load by using finite element method, for the first time. To investigate the response of thick beam accurately, two-dimensional plane stress problem is assumed to describe the constitutive behavior of thick beam structure. The material is distributed gradually through the thickness of each layer by generalized power law function. The Kelvin-Voigt viscoelastic constitutive model is exploited to include the material internal damping effect. The governing equations are obtained by using Lagrange's equations and solved by using finite element method with twelve -node 2D plane element. The dynamic equation of motion is solved numerically by Newmark implicit time integration procedure. Numerical studies are presented to illustrate stacking sequence and material gradation index on the displacement-time response of cantilever beam structure. It is found that, the number of waves increases by increasing the graduation distribution parameter. The presented mathematical model is useful in analysis and design of nuclear, marine, vehicle and aerospace structures those manufactured from functionally graded materials (FGM).

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.127-132
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• 2003

Through advance in construction techniques, engineering progress, availability of new materials, and economic considerations, buildings are becoming taller, lighter, and more flexible. In addition, today/s buildings are largely of regular geometric shape with smooth glass metal exteriors, which increase the likelihood of vortex shedding. The wind induced oscillation of the building, if not properly damped, could cause occupant discomfort and other problem. This paper will deal with residual building structure equipped with viscoelastic dampers. And the dampers are installed on the 42th story according to the maximum relative deformation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.808-812
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• 2002

The feasibility of using elastic dampers to mitigate earthquake-induced structural response is studied in this paper. The properties of elastic dampers are briefly described. A procedure for evaulating the elastic damping effect when added to a structure is proposed in which the damping effect of elastic dampers is incorporated into modal damping ratios through an energy approach. Computer simulation of the damped response of a multi-storey steel frame structure shows significant reduction in floor displacement levels.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.687-692
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• 2002

In order to verify the effectiveness of adding visooelastic dampers to full-scale steel frame structure on the reduction of their seismic and wind response a experimental work was carried out. First, The test was conducted on the VE dampers subjected to sinusoidal excitations under a variety of ambient temperatures, frequency, and the damper strain. Results from these tests showed that the viscoelastic dampers have high energy dissipation capacity. Second, The vibration tests was conducted of the full-scale steel frame structure with md without added VE dampers at different temperatures. Viscoelastically damped full-scale structure test result on the effect of ambient temperature show that viscoelastic dampers are very effective in reducing excessive vibration of the structure due to sinusoidal excitation over a wide ringe of ambient temperature.

• Smart Structures and Systems
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• 제8권3호
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• pp.239-252
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• 2011

In this study, the performances of a passive tuned mass damper (TMD) and a semi-active TMD (STMD) were evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for damped structures with a passive TMD and with a STMD proposed in this study. The displacement spectra confirmed that the STMD provided much better control performance than passive TMD and the STMD had less stroke requirement. Also, the robustness of the TMD was evaluated by off-tuning the frequency of the TMD to that of the structure. Finally, numerical analyses were conducted for an inelastic structure of hysteresis described by the Bouc-Wen model. The results indicated that the performance of the passive TMD whose design parameters were optimized for an elastic structure considerably deteriorated when the hysteretic portion of the structural responses increased, and that the STMD showed about 15-40% more response reduction than the TMD.

• Journal of Advanced Marine Engineering and Technology
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• 제27권1호
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• pp.24-32
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• 2003

The PID controller has been widely used in industrial applications due to its simple structure and robustness. Even if it is initially well tuned, the PID controller must be retuned to maintain acceptable performance when there are system parameter changes due to the change of operation conditions. In this paper, a self-tuning control scheme which comprises a parameter estimator, a NN-based rule emulator and a PID controller is proposed, which can cope with changing environments. This method involves combining neural networks and real-coded genetic algorithms(RCGAs) with conventional approaches to provide a stable and satisfactory response. A RCGA-based parameter estimation method is first described to obtain the first-order with time delay model from over-damped high-order systems. Then, a set of optimum PID parameters are calculated based on the estimated model such that they cover the entire spectrum of system operations and an optimum tuning rule is trained with a BP-based neural network. A set of simulation works on systems with time delay are carried out to demonstrate the effectiveness of the proposed method.