• 국제초고층학회논문집
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• 제5권3호
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• pp.167-176
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• 2016

This paper describes a large tuned mass damper (TMD) developed as an effective seismic control device for an existing highrise building. To realize this system, two challenges needed to be overcome. One was how to support a huge mass that has to move in any direction, and the second was how to control mass displacement that reaches up to two meters. A simple pendulum mechanism with strong wires was adopted to solve the first problem. As a solution to the important latter problem, we developed a high-function oil damper with a unique hydraulic circuit. When the mass velocity reaches a certain value, which was predetermined by considering the permissible displacement, the damper automatically and drastically increases its damping coefficient and limits the mass velocity. This velocity limit function can effectively and stably control the mass displacement without any external power. This paper first examines the requirements of the TMD using a simple model and clarifies the constitution of the actual TMD system. Then the seismic upgrading project of an existing high-rise building is outlined, and the developed TMD system and the results of performance tests are described. Finally, control effects for design earthquakes are demonstrated through response analyses and construction progress is introduced.

• Tribology and Lubricants
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• 제40권2호
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• pp.54-60
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• 2024

This study experimentally identifies the effects of end shape, clearance, total damper length, journal eccentricity ratio, oil supply pressure, and oil flow rate on the damping coefficient of a squeeze film damper (SFD) with piston ring seal ends and a central groove. The SFD is composed of a lubricating fluid flowing between the outer race of a rolling element bearing and cartridge, along with an anti-rotation pin to prevent the rotation of the outer race. The device provides additional viscous damping to a rotating system. Additionally, piston ring seals attached at both ends of the damper increase the damping coefficient of the rotating system by reducing oil leakage. Because these different design conditions affect the damping coefficient of an SFD, we perform experiments including different conditions. Tests show that the damping coefficient increases significantly in the SFD with piston ring seal ends compared with the SFD with open ends. The damping coefficient also increases with increasing total damper length and journal eccentricity ratio, and decreases with increasing clearance. Additionally, in contrast to the trend observed for the SFD with open ends, the damping coefficient for the SFD with piston ring seal ends increases with increasing supply pressure and flow rate as the frequency decreases but shows consistent results as the frequency increases.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.124-126
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• 2008

In this Paper, the modeling of the electromagnetic damper for automobile suspension is presented and the validation of the model is demonstrated by experiments. An electromagnetic damper, composed of a rotary DC motor, and a ball screw and nut. The damper then operates as a linear electric actuator. The damper then operate as a linear electric actuator. The results indicate the proposed system is feasible and it is proved that the electromagnetic damper has better than oil damper of passive control system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.525-528
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• 2008

The dynamic range of MR damper is the most important characteristics for the usage of semi-active control system. The damping force can be increased by simply decresing the orifice gap in the traditional oil damper, but it deteriorate the dynamic range in MR damper. In this paper, the multi-stage electro-magnetic core is suggested to maintain the performance of MR damper with a large damping force. The MR damper with 3 stage core is designed and manufactured for testing and analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.744-749
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• 2011

Silicon oil in viscous fluid damper has a viscoelastic feature that show stiffness besides damping. These properties depend on frequency and are non-linear. A lot of research has been conducted in order to identify viscoelastic damper with mathematical model. Fractional Derivative Maxwell Model has been widely used, but this model did not explain the effect of damper size change on the damper performance. In this paper, the experimental study was conducted to validate damper's dynamic behaviors when total damper's size is changed while maintaining same aspect ratio and orifice size.

• 드라이브 ㆍ 컨트롤
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• 제14권2호
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• pp.45-51
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• 2017

Semi-submersible drilling rigs are offshore plants that perform functions such as ocean exploration for oil and gas acquisition, drilling and production, and storage and unloading of crude oil and gas. Semi-submersible drilling rigs use watertight dampers as emergency buoyancy holders. Since the watertight damper is an emergency shutoff device, it is mainly driven by a pneumatic driving system that can operate without a power supply. The pneumatic driving system has highly non-linear characteristics due to compressibility of air and external disturbance such as static and Coulomb friction. In this paper, a new control algorithm is proposed for a watertight damper driving system based on the sliding mode control with a disturbance observer. To evaluate control performance and robust stability of the designed controller, the control results were compared with the results obtained using the state feedback controller. As a result, it was confirmed that the pneumatic driving system for driving the watertight damper using the sliding mode controller with a disturbance observer can obtain excellent control performance against the parameter changes and the disturbance input.

• Tribology and Lubricants
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• 제16권3호
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• pp.157-165
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• 2000

A discharge free Electro-Rheological Squeeze Film Damper (ER-SFD) with predetermined-clearances at leakage ends can inherently eliminate electric discharge problems while still supplying stable leakage control. Test results show that the damping force of the slotted-ring ER-SFD is mainly affected by electric voltage, oil supply pressure, position of the damper and ratio of effective surface area of slotted-rings. As the supply voltage is larger, the amplitudes of both slotted ER-SFD and rotor are decreased at first and second critical speeds. The influence of the oil supply pressure and the effective surface area ratio was shown mainly near the first critical speed. The effective surface area ratio of slotted-rings influences the reduction of flexible rotor vibration. As a result, experimental results confirm that the slotted-ring ER-SFD satisfactorily controls the flexible rotor vibration, while eliminates the inherent electric discharge problems in conventional ER-SFDs.

• 한국지진공학회논문집
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• 제11권3호
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• pp.53-62
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• 2007

이 연구에서는 작용하는 하중특성에 따라 적절한 감쇠력을 발휘할 수 있는 복합감쇠기(complex damper)를 제안하고 그 유용성을 장대교량의 지진응답해석을 통하여 검토하였다. 제안한 복합감쇠기는 두개 이상의 탄소성감쇠기(elasto-plastic damper)와 오일 감쇠기(oil damper)의 조합에 의하여 구성되며, 탄소성감쇠기의 변위의존적인 특성과 오일감쇠기의 속도의존적인 특성을 적절히 결합함으로서 효율적인 감쇠시스템의 구성이 가능하게 하였다. 중소형의 지진이나 작은 진폭의 진동에서는 오일감쇠기가 주로 진동을 흡수하며, 발생 빈도가 낮으나 규모가 큰 지진 등에 대해서는 탄소성 감쇠기가 진동에너지를 흡수한다. 이와 같이 복합감쇠기는 두 가지 종류의 감쇠기 역할을 잘 구분시켜 경제적이고 제진효율성이 뛰어난 설계를 가능하게 한다. 복합감쇠장치의 수학적 모델을 정립하였고, 수치모사를 통하여 응답특성과 효율성을 평가하였다. 수치모사 결과, 복합감쇠기는 단일의 수동형감쇠기를 이용하는 경우보다 뛰어난 감쇠효과를 더욱 경제적으로 구현할 수 있으며 내진성능을 크게 향상시킬 수 있는 것으로 나타났다.

• Tribology and Lubricants
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• 제24권3호
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• pp.147-153
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• 2008

The effect of oil supply pressure on the performance of vapor cavitated short squeeze film dampers is examined. Vapor cavitation is characterized by film rupture occurring as a result of evaporating oils. The pressure of vapor cavity in the film is almost zero in absolute pressure and nearly constant. Pan's model about the shape of vapor cavity is utilized for studying the effect of vapor cavitation on the damping capability of a short squeeze film damper. As the level of oil supply pressure is increasing, vapor cavitation is suppressed so that the direct damping coefficient increases and the cross coupled damping coefficient decreases. Futhermore, the analysis of the unbalance responses of a rigid rotor supported on cavitated squeeze film dampers shows that a significant reduction in rotor amplitude and force transmissibility is possible by controlling the oil supply pressure into short squeeze film dampers.

• 동력기계공학회지
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• 제1권1호
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• pp.98-105
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• 1997

In general, crankshafts which are used in internal combustion reciprocating engines are subjects to high torsional vibration. Therefore, a damper is often used to minimize the torsional vibration in reciprocating engines. In this paper, in order to investigate damping performance of viscous damper, the real effective viscosity and complex damping coefficient of silicone oil, and the effective inertia moment of inertia ring are calculated considering the relative motion between damper casing and inertia ring. Based on these results multi-cylinder shaft is modeled into equivalent 2-degree of freedom system and optimum condition is estimated by calculating the amplification factor of viscous damper. Also the test damper was manufactured according to the result of theoretical investigation, the performance and durability was ascertained through experimental examination.