• Journal of Power System Engineering
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• v.6 no.2
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• pp.33-39
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• 2002

Commercial vehicles are mostly subjected to relatively rougher ground environment than passenger vehicles. Many driver's seats of commercial vehicles have suspension system with spring and dampers. Then, impact or vibrative forces transmitted from the vehicle to the driver can be attenuated. This study deals with a ride evaluation method using sky-hook control algorithm for the suspension dampers. Vibration amplitude transmissibilities were compared between passive dampers and semi-active dampers with sky-hook control method.

• Journal of Power System Engineering
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• v.6 no.2
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• pp.82-87
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• 2002

For the dynamic behavior evaluation of a semi-active vibration control system, it is very important to use an accurate mathematical model for the hydraulic damper applied to the control system. In this study, a mathematical model for a symmetric type hydraulic damper was suggested. In this model, the effects of gas volume and oil temperature variation on the bulk modulus of oil were considered. The dynamic behavior of the damper was investigated by experiments and simulations. It was confirmed that the pressure variation, damping force, and mean pressure variation could be estimated with comparatively good precision by the suggested mathematical model. Moreover, it was shown that excessive pressure rise can be generated by the oil expansion due to the heat energy transformed from the exciting energy of the damper for a short period of the damper operation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1048-1053
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• 2003

This paper proposed a MR(Magneto-rheological) seat damper for a commercial vehicle. After formulating the governing equation of motion, an appropriate size of damper is designed and manufactured. Following the equation of fie d-dependent damping force characteristics, a semi-active seat suspension installed with the proposed MR-damper is constructed and its dynamic model id established, Subsequently, vibration isolation performance of the semi-active suspension system is demonstrated by incorporating with a MRAC(Model referenced adaptive control) fer the MR Seat Damper

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.969-974
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• 2008

As the railway becomes higher, the reliable stability and riding comfort of higher railway are required. To improve the riding comfort of high-speed trains, it is very helpful to use active suspension system for railway. In Japan, the high-speed train, Shinkansen has adopted semi-active suspension system and now it is running in the main trunk. In this paper, the authors introduce several technical trends of vibration control methods of Japanese Shinkansen. And the installation of semi-active suspension to HSR 350x and the test result of test run on the Kyoung-Bu high speed ling are also explained. After development of HSR 350x, new R&D national project of high speed train is progressed by Ministry of Land, Transport, and Maritime Affairs. This project is the development of Electric Multiple Unit of high speed train with 400km/h of maximum test speed. These result would be helpful to progress next generation high speed project.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.674-675
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• 2012

• Coupled systems mechanics
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• v.6 no.2
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• pp.175-187
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• 2017

This paper deals with a uniform cantilever Euler-Bernoulli beam subjected to follower and transversal force at its free end as a model for a pipe conveying fluid under electromagnetic damper force. The electromagnetic damper is composed of a permanent-magnet DC motor, a ball screw and a nut. The main objective of the current work is to reduce the pipe vibration resulting from the fluid velocity and allow it to transform into electric energy. To pursue this goal, the stability and vibration of the beam model was studied using Ritz and Newmark methods. It was observed that increasing the fluid velocity results in a decrease in the motion of the free end of the pipe. The results of simulation showed that the designed semiactive electromagnetic damper controlled by on-off damping control strategy decreased the vibration amplitude of the pipe about 5.9% and regenerated energy nearly 1.9 (mJ/s). It was also revealed that the designed semi-active electromagnetic damper has better performance and more energy regeneration than the passive electromagnetic damper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.219-224
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• 2016

The vibration control performance of a semi-active damper connected to adjacent buildings subjected to seismic loads was investigated. The MR damper was used as a semi-active control device. A fuzzy logic control algorithm was used for effective control of the adjacent buildings connected to the MR damper. In the buildings control coupled with a MR damper, the response reduction of one building results in an increase in the response in another building. Because of these conflict characteristics, multi-objective optimization is required. Therefore, a fuzzy logic control algorithm for the control of a MR damper was optimized using a multi-objective genetic algorithm. Based on numerical analyses, the semi-active fuzzy control of MR damper for adjacent coupled buildings can provide good control performance.

• Structural Engineering and Mechanics
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• v.33 no.1
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• pp.79-93
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• 2009

This paper investigates the possibility of controlling the response of typical portal frame structures to blast loading using a combination of semi-active and passive control devices. A one storey reinforced concrete portal frame is modelled using non-linear finite elements with each column discretised into multiple elements to capture the higher frequency modes of column vibration response that are typical features of blast responses. The model structure is subjected to blast loads of varying duration, magnitude and shape, and the critical aspects of the response are investigated over a range of structural periods in the form of blast load response spectra. It is found that the shape or length of the blast load is not a factor in the response, as long as the period is less than 25% of the fundamental structural period. Thus, blast load response can be expressed strictly as a function of the momentum applied to the structure by a blast load. The optimal device arrangements are found to be those that reduce the first peak of the structural displacement and also reduce the subsequent free vibration of the structure. Semi-active devices that do not increase base shear demands on the foundations in combination with a passive yielding tendon are found to provide the most effective control, particularly if base shear demand is an important consideration, as with older structures. The overall results are summarised as response spectra for eventual potential use within standard structural design paradigms.

• Smart Structures and Systems
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• v.4 no.5
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• pp.697-710
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• 2008

Long steel stay cables, which are mainly used in cable-stayed bridges, are easy to vibrate because of their low inherent damping characteristics. A lot of methods for vibration reduction of stay cables have been developed, and several techniques of them have been implemented to real structures, though each has its limitations. Recently, it was reported that smart (i.e. semi-active) dampers can potentially achieve performance levels nearly the same as comparable active devices with few of the detractions. Some numerical and experimental studies on the application of smart damping systems employing an MR fluid damper, which is one of the most promising smart dampers, to a stay cable were carried out; however, most of the previous studies considered only one specific control algorithm in which they are interested. In this study, the performance verification of MR fluid damper-based smart damping systems for mitigating vibration of stay cables by considering the four commonly used semi-active control algorithms, such as the control algorithm based on Lyapunov stability theory, the maximum energy dissipation algorithm, the modulated homogeneous friction algorithm and the clipped-optimal control algorithm, is systematically carried out to find the most appropriate control strategy for the cable-damper system.

• Smart Structures and Systems
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• v.10 no.3
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• pp.193-207
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• 2012

New insights into our previously proposed hybrid-type method for vibration control are highlighted in terms of energy analysis, such as the assessment of energy efficiency and system stability. The hybrid method improves the bang-bang active method by combining it with an energy-recycling approach. Its simple configuration and low energy-consumption property are quite suitable especially for isolated structures whose energy sources are strictly limited. The harmful influence of the external voltage is assessed, as well as its beneficial performance. We show a new chattering prevention approach that both harvests electrical energy from piezoelectric actuators and eliminates the displacement-offset of the equilibrium point of structures. The amount of energy consumption of the hybrid system is assessed qualitatively and is compared with other control systems. Experiments and numerical simulations conducted on a 10-bay truss can provide a thorough energy-efficiency evaluation of the hybrid suppression system having our energy-harvesting system.