• Journal of the Society of Disaster Information
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• v.17 no.4
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• pp.829-838
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• 2021

Purpose: The Air Spring Damper System (ASDS) is proposed when existing concrete structures that have not been seismic resistant for economic and technical reasons or low-rise concrete structures that are difficult to earthquake. Method: To conduct a study on the damping force antigen in the kinetic equation of free vibration, we analyze whether this device has damping ability as a damper experimentally and theoretically, and examine the possibility of field application. Result: The air damper system is considered to be more economical than steel hysteresis dampers even if the number of dampers increases due to its easy manufacture and construction and low restrictions on shape, size, material, etc. Conclusion: In an air spring damper system, it is essential to reduce the diameter of the air inlet/outlet hole to improve the damping ratio, and in this case, if the diameter exceeds a certain lower limit, consideration of the compressibility of air is required, so further research is needed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.286-292
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• 1993

The classical way to improve the control performance is studied on the aspects of gun/turret deive systens. Two ways are discussed comparadively ; electrical case and electro-hydraulic case. System parameters are analytically studied in terms of resonance frequencies, and damping and gear train ratio effects are checked in relation to resonance frequency increase. Benefit of the feedback is discussed to increase the damping of the natural frequency lending to bandwidth increase.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.688-693
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• 2009

The response characteristics of power system frequency are determined by generator droop characteristics and load damping properties. The characteristics of governor droops are termed by generators constant, while those of load damping by load constant. In this paper, the generator constant and the load constant are assessed by measured data at the event of generator trips.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.942-946
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• 1995

Using database obtained by means of experiments, or using the synamic behaviour analysis program of automotive shock absorber, database system is constructed within the limits of adequate reliability. Thus constructed data base can be used to find out corresponding specification of shock absorber design parameters to the required damping ability and tolerance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.227-231
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• 1995

This paper describes a basic programming and interfacing modele which can link DataBase form experiments and dynamic analysis program of chock absorber within the limit of adequate reliability. The system developed can provid a user specific Database of shock absorber within the required damping performance and endurable tolerance, thus show a good application possibilities in commercial vehicle design.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.8-13
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• 2011

A compact array system of small buoys is used for wave energy extraction. To evaluate the performance of this system, hydrodynamic analysis is carried out in regular waves using the higher order boundary element method. The motion response of each buoy is calculated considering hydrodynamic interactions caused by other buoys. The effect of energy extraction device is modeled as a linear damping load. The efficiencies of energy conversion are compared using the various sizes and arrangements of the array system and the damping coefficients for energy extraction. The increase in size or the packing ratio of the system gives better efficiency. However, the wave condition and the cost for the system should be considered to optimize performance from the perspective of engineering and economics. The proposed nondimensionalized damping coefficient for energy extraction is 0.1~0.5.

• Tribology and Lubricants
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• v.40 no.2
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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.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.27-36
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• 2014

This paper presents an adaptive wide-area damping controller (WADC) based on generalized predictive control (GPC) and model identification for damping the inter-area low frequency oscillations in large-scale inter-connected power system. A recursive least-squares algorithm (RLSA) with a varying forgetting factor is applied to identify online the reduced-order linearlized model which contains dominant inter-area low frequency oscillations. Based on this linearlized model, the generalized predictive control scheme considering control output constraints is employed to obtain the optimal control signal in each sampling interval. Case studies are undertaken on a two-area four-machine power system and the New England 10-machine 39-bus power system, respectively. Simulation results show that the proposed adaptive WADC not only can damp the inter-area oscillations effectively under a wide range of operation conditions and different disturbances, but also has better robustness against to the time delay existing in the remote signals. The comparison studies with the conventional lead-lag WADC are also provided.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.205-211
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• 2007

In this paper, foam-composite sandwich structures for EDM machine tool components such as column and column block designed by controlling stacking sequences and cross-sectional dimensions of the composite structures. The original column block is a box-shaped structure made of aluminum connecting a column and a Z-stage of the system. This research was focused on the design of efficient column block structure using a foam-composite sandwich structure which have good bending stiffness and damping characteristics to reduce the mass and increase damping ratio of the system. Vibration tests for getting damping ratio with respect to the stacking angle and thickness of the composites were carried out. Finite element analyses for static defection and vibration behaviour were also carried out to find out the appropriate stacking conditions; that is, stacking sequence and rib configuration. From the test and analysis results it was found that composite-foam sandwich structures for the microfactory system can be successful alternatives for high precision machining.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.70-75
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• 2015

The influence of reversed austenite on the damping capacity in austenitic stainless steel with two phase of martensite and reversed austenite was investigated. The two phases of deformation induced martensite and reversed austenite was obtained by an reverse annealing treatment at $500^{\circ}C{\sim}700^{\circ}C$ for various time after 70% cold rolling. With an increase of the reverse annealing treatment temperature and time, volume fraction of reversed austenite was rapidly increased. With an increase of volume fraction of reveresd austenite, damping capacity was rapidly increased. At same volume of reveresd austenite, damping capacity of reversed austenite obtained by reverse annealing treatment at $700^{\circ}C$ for various time was higher then reveresd austenite obtained by reverse annealing treatment at $500^{\circ}C{\sim}700^{\circ}C$ for 10min. Thus, the damping capacity was affected greatly by reversed austenite obtained by annealing treatment at $700^{\circ}C$ for various time.