• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.349.1-349
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• 2002

This paper presents investigation of damping characteristics of squeeze mode type MR mount experimently. The MR mount proposed in the study has variable damping characteristics according to the applied magnetic field strength. Impact and force excitation tests were performed. The dynamic property of the mount using MR fluid was compared with that of the mount using conventional oil. (omitted)

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.587-590
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• 2000

By using the information obtained from output of the MR(Magneto Resistive) sensor for an unmanned vehicle system which is used in the Local Position System. We develop an algorithm that decides the distance and directions between the guideline made by magnets and vehicle, and make an unmanned vehicle driving system that is steered by PD controller and MR sensor

• Wind and Structures
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• 제7권5호
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• pp.293-304
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• 2004

The Dongting Lake Bridge is a cable-stayed bridge crossing the Dongting Lake where it meets the Yangtze River in southern central China. Several intensive wind-rain induced vibrations had been observed since its open to traffic in 1999. To investigate the possibility of using MR damping systems to reduce cable vibration, a series of field tests were conducted. Based on the promising research results, MR damping system was installed on the longest 156 stay cables of Dongting Lake Bridge in June 2002, making it the worlds first application of MR dampers on cable-stayed bridge to suppress the wind-rain induced cable vibration. As a visible and permanent aspect of the bridge, the MR damping system must be aesthetically pleasing, reliable, durable, easy to maintain, as well as effective in vibration mitigation. Substantial work was done to meet these requirements. This paper describes field tests and the implementation of MR damping systems for cable vibration reduction. Three-years reliable service of this system proves its durability.

• 한국지진공학회논문집
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• 제10권6호
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• pp.47-56
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• 2006

지진응답 제어를 위하여 사장교 구조물에 장착된 준능동MR 댐퍼의 경제적 효율성 평가기법을 제안하였으며, 다양한 지반운동 특성에 대하여 비용효율성을 극대화하는 MR 댐퍼의 최적용량에 대한 분석을 수행하였다. MR 댐퍼의 비용효율성 평가를 위하여 생애주기비용 개념을 적용하였으며, 생애주기비용을 이루는 비용항목 중 손상비용의 기대값을 평가하기 위하여 지진재해로 인한 사장교의 파괴확률을 추정하였다. 사장교의 파괴로 인한 직 간접 손상비용의 규모를 매개변수로 하여 비용효율성을 평가하였다. 비용효율성 평가지수는 MR 댐퍼의 장착으로 인한 추가 투자비용과 사장교 구조물의 손상비용으로 이루어진 함수로서, 탄성받침이 사용된 기존의 설계에 대한 경제적 효율성을 나타내도록 정의하였다. 사장교의 지진응답 제어를 위하여 장착된 MR 댐퍼는 경제적으로 효율적인 대안인 것으로 나타났다. 지반운동의 특성과 손상비용 규모에 대한 MR 댐퍼의 최적 용량을 분석한 결과, 지진위험도 및 손상비용 규모가 커짐에 따라 가장 높은 비용효율성을 가지는 MR 댐퍼용량이 증가하는 것을 확인할 수 있었다.

• 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.

• 한국소음진동공학회논문집
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• 제26권4호
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• pp.443-448
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• 2016

A novel Permanent Magnet based Magneto Rheological (PM-MR) damper is proposed in this paper. The principle of proposed MR damper is achieved by designing a linearly varying magnetization area with-respect to the movable permanent magnetic based piston setup. Nowadays, commercially available MR damper uses electromagnetic coils for generating the variable magnetic fields corresponding to the variable damping force. The amount of magnetic field produced by the electromagnetic coils are depends on the biasing current of voltage source. The key enabling concept of the proposed MR damper is to replace the electromagnetic coils and the voltage sources by utilizing the variable area based permanent magnetic piston setup. The proposed unique design structure of PM-MR damper has an increasing shear mode damping force with the piston movement in both jounce and rebound motion. In this research, analytical model of the proposed structure is derived and the structural design of proposed concept is verified using numerical CAD tool. As a result, the damping force is increase when piston movement in both jounce and rebound motion.

• 한국소음진동공학회논문집
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• 제26권5호
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• pp.511-517
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• 2016

This paper presents dynamic characteristics of a new actuator using magneto-rheological(MR) fluid between two electrode type coils. The concept of the actuator is to strengthen the force due to the magnetic field produced by the electrode-coil for MR fluid. The amount and direction of current input to the electrode-coils decide the characteristics of contraction-mode and extension-mode. For achieving the required actuating displacement and actuating force, the yield stress of the MR fluid between two electrode-coils is precisely changed by the input current. In this work, the MR fluid is operated in squeeze mode. The experimental results shown in this paper depict that it can be applied in the micro-level displacement and vibration control system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.65-70
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• 2010

This paper presents experimental performance evaluation of a magnetorheological (MR) damper for integrated isolation mount for ultra-precision manufacturing system. The vibration sources of the ultra-precision manufacturing system can be classified as follows: the one is the environmental vibration from the floor and the other is the transient vibration occurred from stage moving. The transient vibration occurred from the stage moving has serious adverse effect to the process because the vibration scale is quite larger than other vibrations. Therefore in this research, a semi-active MR damper, which can control the transient vibration, is adopted. Also the stage needs to be isolated from tiny vibrations from the floor. For this purpose, a dry-frictionless MR damper is required. In order to achieve this goal, a novel type of MR damper is originally designed and manufactured in this work. Subsequently, the damping force characteristics of MR damper are evaluated by simulation and experiment. In addition, the vibration control performance of the MR damper associated with the stage mass is evaluated.

• 한국전산구조공학회논문집
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• 제19권3호
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• pp.239-245
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• 2006

본 연구에서는, 지진하중에 의해 구조물에 발생하는 진동을 제어하기 위하여 토글 시스템의 비선형성을 연구하고, 자기유변유체(MR) 감쇠기를 장착한 토글 가새시스템의 성능을 평가하였다. Bingham 모델로 표현되는 MR감쇠기의 제어력이 속도의 함수인 점을 고려하여, 토글 가새시스템에 의한 속도증폭계수를 계산하였고 토글 형태에 대한 증폭계수효과를 평가하였다. 특히 강한 지진하중에서 쉐브론과 대각가새 등의 전형적인 가새시스템에 장착된 MR감쇠기가 충분한 응답감소효과를 제공하지 못하는 경우에, 토글 가새시스템을 사용하여 제어성능을 크게 강화시키는 것을 수치해석 결과를 통하여 확인하였다.

• Smart Structures and Systems
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• 제16권6호
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• pp.1003-1021
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• 2015

MR dampers have been proposed for the control of cable vibration of cable-stayed bridge in recent years due to their high performance and low energy consumption. However, the highly nonlinear feature of MR dampers makes them difficult to be designed with efficient semi-active control algorithms. Simulation study has previously been carried out on the cable-MR damper system using a semi-active control algorithm derived based on the universal design curve of dampers and a bilinear mechanical model of the MR damper. This paper aims to verify the effectiveness of the MR damper for mitigating cable vibration through a full-scale experimental test, using the same semi-active control strategy as in the simulation study. A long stay cable fabricated for a real bridge was set-up with the MR damper installed. The cable was excited under both free and forced vibrations. Different test scenarios were considered where the MR damper was tuned as passive damper with minimum or maximum input current, or the input current of the damper was changed according to the proposed semi-active control algorithm. The effectiveness of the MR damper for controlling the cable vibration was assessed through computing the damping ratio of the cable for free vibration and the root mean square value of acceleration of the cable for forced vibration.