• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.47-51
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• 2015

In this paper, feasibility of dynamic characteristics recovery of delaminated composite structure is numerically studied by using active control algorithm and piezoelectric actuator. Macro-fiber composite(MFC), which has great flexibility and high actuating force, is considered as an actuator in this work. After construction of finite element model for delaminated composite structure based on improved layerwise theory, modal characteristics are investigated and changes of natural frequencies and mode shapes, caused by delamination, are observed. Then, active control algorithm is realized and implemented to system model and control performances are numerically evaluated. Dynamic characteristics of delaminated composite structure are effectively recovered to those of healthy composite structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.42-45
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• 2008

다목적 공간 및 공연장은 공연 또는 강연을 위한 공간뿐만 아니라 상점, 식당 및 체육 공간 등 다양한 용도의 공간이 인접되고 있다. 다양한 공간이 인접할 경우 기존의 다목적 공연장에서는 발생하지 않았던 다양한 소음 진동 문제들이 발생한다. 본 연구는 강연 및 공연을 위한 다목적 공간 상부에 식당 및 체육 시설로 활용되는 공간이 배치되어 바닥충격음 문제가 발생할 가능성이 있었다. 바닥충격음의 강당으로의 전달을 차단하기 위하여 기본 구조체에 대한 바닥충격음 차단성능을 측정하여 적절한 저감 대책을 수립하였다. 저감대책으로는 상층부 철골 슬래브와 강당의 철골 구조의 구조적 분리, 유연한 마감재 적용, 슬래브로의 충격진동 차단을 위한 제진재 적용, 이중천장 구조 및 천장내부 흡음구조 형성 등의 종합적인 대책을 수립하였다. 이를 통해 경량충격음 및 중량충격음을 효율적으로 차단하였다. 또한 강당 공간은 강연 및 집회의 공간으로 활용될 수 있도록 하기 위하여 적절한 잔향시간 및 음성 명료도 확보가 필요하다. 플러터 에코, 과도한 잔향시간, 음의 사각지대 등을 최소화하기 위하여 측벽 형태 개선, 천장 반사판 형태를 개선하였다. 또한 측벽에서 진동 등의 영향으로 발생되는 떨림현상을 억제하기 위하여 측벽 내부를 흡음재로 충전하는 등의 대책을 수립하여 적용하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.108-118
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• 2006

The purpose of this study is to investigate the effectiveness of a LQG Hybrid controller to suppress the earthquake disturbance for the building structure. The ground acceleration of N-S component of El-Centro earthquake was scaled to confirm that the building behaved within the elastic range. The tuned mass damper(TMD) on the top floor regulated by LQG algorithm was designed to control the floor displacements. The displacement responses of the hybrid control were compared with those obtained from an active control along with a passive control. The results showed that the LQG hybrid control used approximately 50% less input forces than an active control to satisfy the performance criteria.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.5 s.45
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• pp.21-28
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• 2005

This paper proposes a shaking table test considering the dynamic soil strcuture interaction (SSI) by using the accelerations measured from superstructure and shaking table. The proposed method based on the substructure method is that only superstructure is used as an experimental model and dynamic soil stiffness is reflected on the controller of shaking table for soil model. At the moment, an experimental superstructure is excited by a shaking table with the motion required to emulate the dynamic behavior of total SSI system. First, the validity of the proposed method is verified by the verification model of numerical simulation, which is derived from the equation of motion of SSI system under consideration. Also, the applicability of the proposed method to shaking table test is numerically verified from the simulation model incorporating the transfer function of shaking table.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.569-577
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• 2012

In this study, a theoretical investigation of optimized sleeper spacing which can suppress resonances of a railway track is attempted. To achieve this, we introduced a minimization problem in which the objective function is given by the wave transmittance and the design variable is defined by sleeper distribution. In the analysis the rail is modeled by a Timoshenko beam and the sleeper is represented by a mass. The infinite track analysis is realized by attaching the transmitting boundaries at both ends of the finite optimization region. Through numerical analyses the sleeper spacing effective in reduction of the transmittance is discussed. Furthermore, the feasibility of the proposed method is validated in the aspect of vibration reduction through response analyses for a harmonic load.

• Journal of KSNVE
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• v.4 no.1
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• pp.6-11
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• 1994

국내 반도체 산업계의 현재 발전속도에 비추어 보아, 현재의 4M DRAM의 개발 성공과 더불어 가까운 시일내에 16M DRAM의 양산단계에 와 있고 더 나아가 64M DRAM 의 개발을 예상할 수 있다. 이와 같은 초고집적회로의 출현에 따라 이를 생샨하기 위한 장비는 물론이고, 이를 설치하여 운용하는 반도체 제조공장에 대한 대책이 시급 한 실정이다. 따라서 본 연구에서는 향후 선진국에서 기술도입이 불가능할 것으로 예상되는 미진동 제어시스템 개발의 기초 계획안을 수립하고, 이를 통하여 반도체 공장의 수율을 높이는 궁극적 목적을 가지며, 반도체 생산공장의 구조설계 및 방진 시공을 목표로 하여 관련 이론정립 및 미진동 제어시스템을 개발하는데 그 목적이 있다.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.9-15
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• 2003

This paper describes a vibration control by using tuned mass damper(i.e., TMD) for an existing footbridge. The footbridge is the simple steel box girder bridge with main span length of 47.7m. This bridge has light weight, low damping and the 1st bending frequency of 1.84㎐. Its frequency is close to a walking cycle, which is 2㎐. Therefore the uncomfortable resonant vibrations due to a pedestrian walking have occurred frequently. The vibration control by means of TMD for suppressing the pedestrian induced vibration was conducted. Taking into account economical benefits and the easiness of installation, a compact TMD installed within a handrail was designed. From field tests of the TMD, it was confirmed that the structural damping of the bridge via. the compact TMD was enhanced by 13 times and the resonant vibration due to pedestrian walking was suppressed.

• Ingenium
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• v.12 no.2
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• pp.70-77
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• 2005

• Electrical & Electronic Materials
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• v.32 no.3
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• pp.24-31
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• 2019

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.764-765
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• 2009