• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.739-744
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• 2001

In order to investigate the stability of magneto-rheological fluid based squeeze film damper (MR-SFD), its negative stiffness effect, which arises from magnetization of MR-SFD, is identified theoretically and experimentally. The analytical model of MR-SFD includes the magnetic circuit as well as the displacement stiffness associated with the squeeze mode of MRF. Extensive experiments are carried out to measure the magnetic attraction forces generated in the MR-SFD, with the excitation frequency and the eccentricity of the journal varied, which are controlled by an active magnetic bearing. The simulation and experimental results are found to be in good agreement. It is concluded that the negative stiffness effect dominates only in the low frequency region because its effect diminishes in the high frequency region due to the eddy-current loss.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4747-4752
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• 2013

Physical characteristics of a magneto-rheological(MR) fluid can be influenced by a magnetic field. MR fluid is a suspension of micrometer-sized magnetic particles in a base liquid such as oil. Therefore, the key issue is dispersion stability because density of micrometer-sized magnetic particles are different from that of oil. In the present study, dispersion stability and physical characteristics along chemical compositions of MR fluid are investigated. 216 kinds of MR fluids are made by using magnetic powder(#2), surfactant(#2), base oil(#2), functional additive(#3), density(#3) and viscosity(#3). From experimental results, SEM photograph, magnetic flux density, supernatant and sediment of 216 kinds of MR fluids are obtained.

• Journal of KSNVE
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• v.16 no.6 s.84
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• pp.4-10
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• 2006

• Journal of KSNVE
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• v.16 no.6 s.84
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• pp.11-15
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• 2006

• Journal of KSNVE
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• v.16 no.6 s.84
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• pp.22-26
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• 2006

• Proceedings of the KAIS Fall Conference
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• 2000.04a
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• pp.8-8
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• 2000

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.73-81
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• 1999

The intention of this research is to give criteria of designing devices using ER fluids and MR fluids. The Properties of commercial ER fluids and MR fluids are compared using a rotational viscometer. The yield strength is compared upon changes of shear rate, temperature and applied fields. MR fluids seem less sensitive to temperature change than ER fluids. In cases of MR and ER fluid dampers, the time delay and damping force are measured in tension and compression mode when the applied field changes.

• Fire Science and Engineering
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• v.23 no.6
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• pp.16-23
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• 2009

The performance characteristics of a smoke damper, which aims to suppress the penetration of smoke to a safe area, have been tested under the regulation of the FIS 001. However, the improvement of the test methods and the regulation has consecutively been requested. From a view-point of fluid mechanical theory, a pressure control damper, that is installed at the end of the flow control system, is important and it dominates flow characteristics in all designed flow systems. In this study, the weak points of the regulation of the FIS 001 concerned with the pressure control damper was visited and the some important characteristics of the damper was examined. Based on these results, it was confirmed that the effects of flow disturbance in the air supplying duct on the performance of the damper are not significant. This results gives some information for the modification of the experimental regulation concerned to the pressure control damper.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.832-834
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• 2010

본 논문에서는 권선형 엘리베이터 시스템의 종방향의 운동을 표현할 수 있는 운동방정식을 도출한다. 기존의 권선형 엘리베이터 시스템의 종진동을 억제하기 위하여 MR유체를 특징으로 하는 댐퍼를 적용하고, MR댐퍼가 적용된 시스템의 운동방정식을 도출한다. 부하하는 자기장에 따른 엘리베이터 시스템의 종진동 저감의 변화를 관찰하였다.

• Tribology and Lubricants
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• v.2 no.1
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• pp.46-52
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• 1986

얇은 유막위의 타이어 변형해석이나, 압착막댐퍼 설계등의 해석에 응용되는 변동 하중하의 탄성 경계상 유체 압착막의 해석을 Newton-Raphson 반복법을 사용하여 하였다. 유막두께의 계산은 등계수 요소를 사용하여 정확한 계산을 하였고 슬라이더의 궤적은 강쇄진동의 응답곡선과 유사함을 알 수 있었다. 특히 본 연구에서는 미끄럼 속도의 영향을 고려하였으며 유체가 베어링내에 생긴 포켓에 정체하고 있어서 미끄럼의 영향은 속도가 클때를 제외하고는 큰 영향을 미치지 못함을 알 수 있었다.