• Journal of Korean Association for Spatial Structures
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• v.14 no.3
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• pp.57-65
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• 2014

In order to improve the wind performance of buckling-restrained braces (BRBs), Hybrid buckling-restrained braces (H-BRBs) have been studied in Korea. The seismic performance of H-BRBs is different according to the action of VE damper. In this study, the nonlinear time history analyses have been performed on the parameters such as brace types and input earthquakes. The results of the study suggest that H-BRBs meet the BRB's requirement of ANSI/AISC 341-10 only if VE damper is not working during an earthquake.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.740-745
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• 2002

To control vibration of real-size steel structure, a hybrid-type linear motor damper was designed and applied to 30m steel structure at UNISON. The LMD was tuned to the first mode natural frequency of the building. In order to use for simulation data and control parameters, dynamic response characteristics of building and damper were tested. The response of building was reduced by 10 dB with LMD and H$\infty$ algorithm. This value was similar to the result of simulation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.541-548
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• 2003

The design and performance of HTMD(hybrid tuned mass dampers) are evaluated for the response control of a md excited 76-story benchmark building. When a HTMD utilizes active control forces, the optimally designed TMD (Tuned Mass Damper) generates the modal separation at the first natural frequency resulting in difficulties for applying active control forces additionally. Whereas, the modal separation does no occur if the un is designed with the non-optimally designed TMD is used. Therefore, the response control performance of the HTMD with a non-optimally designed TMD is better that one with an optimally designed TMD. Further, the non-optimally designed TMD has an advantage of smaller stroke than the optimally designed TMD relieving the difficulty of limited strokes.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.1-9
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• 2018

In this study, a hybrid control method that adjusts for the existing force control technique has been presented for consideration. The proposed hybrid control technique does away with the chattering phenomenon occurring in existing force control technique and provides high shock absorption efficiency. In order to design the controller for the landing gear with MR damper, the equation of motion of the landing gear was derived. The hybrid controller was designed after constructing a simulation model using Recur-Dyne, multi-body dynamic analysis software. The hybrid controller can reduce the maximum strut force and displacement based on the skyhook controller, and is able to get the high efficiency by making it work for the additional force control technique. In addition, an effective switching control technique and input shaping technique was applied to prevent the chattering in the drop simulation. Finally, the performance of the landing characteristics was evaluated throughout the various drop simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.805-809
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• 2001

This paper is presented to determine the optimal parameters of squeeze film damper using an enhanced genetic algorithm (EGA). The damper design parameters are the radius, length and radial clearance of the damper. The objective function is minimization of a transmitted load between bearing and foundation at the operating and critical speeds of a flexible rotor. The present algorithm was the synthesis of a genetic algorithm with simplex method for a local concentrate search. This hybrid algorithm is not only faster than the standard genetic algorithm, but also gives a more accurate solution and can find both the global and local optimum solution. The numerical example is presented that illustrated the effectiveness of enhanced genetic algorithm for the optimal design of the squeeze film damper for reducing transmitted load.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.1-8
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• 2001

In this paper, a hybrid mass damper using AC-servomotor was designed and developed in order to reduce vibration levels of a 5-story test structure under base excitation. Control performances of the HMD under random and earthquakes excitations are compared with those of TMD through experimental test. It is confirmed that the HMD is more effective to reduce the vibration levels of the test structure especially for the earthquake excitation which excites more than 2 vibration modes of the structure simultaneously.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.256-263
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• 2006

In this paper, an experimental hybrid method, which implements the earthquake response control of a building structure with a TLD(Tuned Liquid Damper) by using only a TLD as an experimental part, is proposed and is experimentally verified through a shaking table test. In the proposed methodology, the whole building structure with a TLD is divided into the upper TLD and the lower structural parts as experimental and numerical substructures, respectively. At the moment, the control force acting between their interface is measured from the experimental TLD with shear-type load-cell which is mounted on shaking table. Shaking table vibrates the upper experimental TLD with the response calculated from the numerical substructure, which is subjected to the excitations of the measured interface control force at its top story and an earthquake input at its base. The experimental results show that the conventional method, in which both a TLD and a building structure model are physically manufactured and are tested, can be replaced by the proposed methodology with a simple experimental installation and a good accuracy for evaluating the control performance of a TLD.

• Structural Engineering and Mechanics
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• v.17 no.3_4
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• pp.573-591
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• 2004

A hybrid control system is presented for seismic-resistant building structures with and without soil-structure interaction (SSI). The hybrid control is a damper-actuator-bracing control system composed of passive and active controllers. An intelligent algorithm is developed for the hybrid system, in which the passive damper is designed for minor and moderate earthquakes and the active control is designed to activate when the structural response is greater than a given threshold quantity. Thus, the external energy for active controller can be optimally utilized. In the control of a multistory building, the controller placement is determined by evaluating the optimal location index (OLI) calculated from six earthquake sources. In the study, the soil-structure interaction is considered both in frequency domain and time domain analyses. It is found that the interaction can significantly affect the control effectiveness. In the hybrid control algorithm with intelligent strategy, the working stages of passive and active controllers can be different for a building with and without considering SSI. Thus SSI is essential to be included in predicting the response history of a controlled structure.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.3
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• pp.236-246
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• 2014

This paper presents a hybrid rubber mount with magnet to isolate effectively the vibration in vehicle, forklift, and so on. The hybrid mount does not have any controller of the magnetic force. Dynamic stiffness of the mount is reduced by only magnetic suction according to the applied magnetic field and damping coefficient increased. Performance of conventional rubber mount with using electromagnet has been investigated by MTS Tester. The governing equation of the hybrid mount was derived and verified by comparison with experimental and theoretical results. The equation can be used practically and usefully in the design of the mount and analysis of the mounting system. The hybrid mount provides excellent performance in vibration isolation and its structure is very simpler than active with controller and a semi-active mount with a functional fluid. Furthermore, production cost of the mount using permanent magnets is very lower than that of the active mount with electromagnets. Therefore, commercial potential of the mount is very high.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.81-86
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• 2012

The shock absorber is very important in various mechanical field. Without the shock absorber, the structure might be broken. For lunar lander, honeycomb shock absorber to absorber the shock by using plastic deformation of honeycomb has been used. It is cheap and simple to use but impossible using again without changing the honeycomb. The oleo-pneumatic type shock absorber is not able to use in the cosmos because it is vacuum and its temperature. This study suggests the hybrid shock absorber combined spring-ratchet mechanical shock absorber and eddy current electromagnetic damper. The ratchet restricts rebound of lunar lander and the spring converts the impact energy to the potential energy of the spring. The eddy current damper dissipates the impact energy by eddy current force without contact between the parts. This hybrid shock absorber is reusable while the honeycomb shock absorber isn't. The impact absorbing test of the hybrid shock absorber was carried out. This paper shows that the compared results the hybrid shock absorber with ratchet and without ratchet and evaluates the possibility of using for lunar lander.