• 한국정밀공학회지
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• 제20권7호
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• pp.128-137
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• 2003

Continuously variable damper can yield diverse damping forces for a single damping velocity. It is widely used in the semi-active suspension system since, with right control logics, it can enhance ride comfort compared to the passive damper while not degrading driving safety. A key to the successful design of the continuously variable damper is the knowledge of its complex and nonlinear characteristics. In this paper, research has been done for analyzing characteristics of the continuously variable damper. Various damper components have been investigated and their effects upon the force-velocity characteristics of the damper have been examined. The effects of the damper characteristics change upon ride comfort and driving safety have also been investigated by numerical simulations.

• 한국안전학회지
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• 제27권1호
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• pp.70-75
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• 2012

For the vibration control of earthquake-excited structures, a pivot-type displacement amplification damper system is proposed and its validity is investigated in this study. A rotational frame amplifies the stroke of the proposed damper system and it can absorb more vibrational energy compared to the conventional dampers of which strokes are not large. In order to prove the effectiveness of the system, time-history analyses are performed with a three story building modelled by a three dimensional frame and numerical results are compared with those for a conventional V-shape braced damper system. In addition, the seismic performances are investigated according to the changes of damper capacity and location.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.151-157
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• 2010

This paper presents the modelling of an MR damper system through extensive experimental studies. The hysteresis of the MR damper is modelled by using the improved Bouc-wen model. A test bed for experimental studies of measuring parameters of the MR damper is designed and implemented. Based on the experimental data, the Bouc-Wen Model is modified for the MR damper system. To check the modelling property, a vehicle suspension system is controlled using a PID controller for the verification of the MR damper model.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.453-460
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• 2006

Stay cables, such as used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Recently some studies have shown that active and semiactive control system using MR damper can potentially achieve both higher performance levels than passive control system and adaptability with few of the detractions. However, a control system including a power supply, controller, and sensors is required to maximize the performance of the MR damper and this complicated control system is not effective to most of large civil structures. This paper proposes a smart complex damping system which consists of toggle system and MR dampers by introducing electromagnetic induction(EMI) system as an external power source to MR damper. The performance of the proposed damping device has been compared with that of the passive-type control systems employing a MR damper, a linear viscous damper, and EMI system.

• Structural Engineering and Mechanics
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• 제63권4호
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• pp.537-549
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• 2017

One of the main concerns of civil engineering researchers is developing or modifying an energy dissipation system that can effectively control structural vibrations, and keep the structural response within tolerable limits during unpredictable events like earthquakes, wind and any kind of thrust load. This article proposes a new type of mass damper system for controlling wideband earthquake vibrations, called Multiple Wall Dampers (MWD). The basic principle of the Tuned Mass Damper (TMD) was used to design the proposed wall damper system. This passive energy dissipation system does not require additional mass for the damping system because the boundary wall mass of the building was used as a damper mass. The multi-mode approach was applied to determine the location and design parameters of the dampers. The dampers were installed based on the maximum amplitude of modes. To optimize the damper parameters, the multi-objective optimization Response Surface Methodology was used, with frequency response and maximum displacement as the objective functions. The obtained structural responses under different earthquake forces demonstrated that the MWD is one of the most capable tools for reducing the responses of multi-storied buildings, and this system can be practically used for new and existing building structures.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.95-104
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• 2016

Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. Use the El Centro seismic(1940, NS) analysis was performed. Analysis results, on the top floor displacement response to the earthquake response, did not have a big effect. However, acceleration response control effect was found to be excellent. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.

• Journal of Advanced Marine Engineering and Technology
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• 제24권6호
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• pp.7-14
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• 2000

Nowadays, the viscous damper using high viscosity oil was much to be used for engine shafting system to reduce the excessive additional stress by torsional vibration. In general, it was assumed that the viscous damper could be modelled having only damping coefficient, that is to say, whose stiffness be ignored. But it is found that there exists a jump phenomenon, as a kind of non-linear vibration, in the actual engine shafting system with a damper of high viscosity. Therefore the damper ring and the casing are modelled as two mass elastic system with a complex viscosity. Also, to analyze a non-linear phenomenon, it is assumed that the viscous damper has a linear stiffness coefficient in proportion to the angular amplitude and a non-linear stiffness coefficient in proportion to cube of the angular amplitude. For the analysis, Quasi-Newton method with BFGS(Broyden-Fletcher-Goldfarb-Shanno) formula is used. Both calculated and measured values are provided in this paper which confirm the possibility of applying non-linear theory to engine shafting system with viscous damper.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.139-145
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• 2018

아웃리거 시스템은 지진이나 풍하중에 의한 동적 응답을 줄이기 위하여 고층 건물의 횡방향 강성을 증가시키는데 널리 사용되고 있다. 풍하중과 지진하중의 동적 특성은 매우 다르기 때문에 스마트 진동 제어 시스템이 아웃리거 시스템과 함께 사용된다면 두 가지 동적 하중에 대해서 효과적으로 사용될 수 있을 것이다. 본 논문에서는 아웃리거 댐퍼 시스템 기반 멀티 해저드 적응형 스마트 구조 제어 시스템에 대한 연구를 수행하였다. 스마트 아웃리거 댐퍼 시스템을 개발하기 위하여 MR 댐퍼를 사용하였다. 수치 해석을 위해 미국에 있는 LA, 찰스턴, 앵커리지의 세 도시에 대한 멀티 해저드 지진하중과 풍하중을 생성하였다. 스마트 아웃리거 댐퍼 시스템의 최적 설계를 위하여 MR 댐퍼 용량에 대한 파라메터 연구를 수행하였다. 유전자 알고리즘으로 최적화된 퍼지 논리 제어기를 이용하여 스마트 제어 알고리즘을 개발하였다. 해석결과를 통하여 아웃리거 댐퍼 시스템 기반 적응형 스마트 구조제어 시스템이 풍하중과 지진하중의 멀티 해저드에 대해서 우수한 제어성능을 나타내는 것을 확인할 수 있었다.

• Steel and Composite Structures
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• 제45권2호
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• pp.249-261
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• 2022

This paper presents a numerical study to develop a guideline for estimating the plastic strength of elliptical steel slit damper with reasonable accuracy. The strut width increases from middle to end in elliptical steel slit damper and it is observed from the past studies that variation of the width is not considered for calculating the plastic strength of the damper. It is also noticed that the existing formulas for predicting plastic strength of this kind of damper may not be accurate and further refinement is warranted. Study is then carried on elliptical steel slit damper made of mild steel and having different geometry to find out equivalency of it with oblong steel slit damper having similar plastic strength. A few three-dimensional finite element models of seismic moment connection system with steel slit damper are developed and validated against past experiments for carrying the present study considering both the material nonlinearity as well as geometric nonlinearity. The results of the parametric studies have been compared with energy quantities and presented graphically to better understand the effects of different parameters on the system. Based on the pattern of parametric study results, closed-form semi-empirical algebraic expression of damper plastic strength is developed for elliptical steel slit damper which shows very good agreement with finite element analysis as well as experiments. This developed expression can now be used for elliptical steel slit damper in replacement with any type of damper in the design of moment connection.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.51-59
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• 2005

본 연구에서는 위의 어려움을 해결하기 위해, 스마트 수동제어 시스템을 제안하였다. 스마트 수동제어 시스템은 MR댐퍼와 EMI시스템으로 구성되며, EMI시스템은 영구자석과 솔레노이드 코일로 이루어진다. EMI시스템은 MR댐퍼의 왕복운동에너지를 전기에너지로 변환하므로, 스마트 수동제어 시스템은 외부 전원 없이 외부하중에 따라 댐퍼의 점성을 바꾸는 적응성을 갖는다. 따라서 간단하고 효율적인 장치로써, 대형토목구조물에 적용 가능하다. 이의 확인을 위해 예제를 통한 수치해석을 수행하였으며, 스마트 수동제어 시스템이 강진에 대해서는 기존의 반능동 제어 MR댐퍼 시스템 보다 우수한 성능을 보인다.