• Advances in concrete construction
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• 제8권2호
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• pp.77-90
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• 2019

This paper aims to investigate vibration frequency decrease (vibration period elongation) of reinforced concrete (RC) structure with unreinforced infill wall and reinforced infill wall exposed to progressively increased artificial earthquake load on shaking table. For this purpose, two shaking table experiments were selected as a case study. Shaking table experiments were carried on 1:1 scaled prototype one bay one storey RC structure with infill walls. The purpose of this shaking table experiment sequence is to assess local behavior and progressive collapse mechanism. Frequency decrease and eigen-vector evolution are directly related to in-plane and out-of-plane bearing capacities of infill wall enclosure with reinforced concrete frame. Firstly, frequency decrease-damage relationship was evaluated on the base of experiment results. Then, frequency decrease and stiffness degradation were evaluated with applied Peak Ground Acceleration (PGA) by considering strength deterioration. Lastly, eigenvector evolution-local damage and eigenvector evolution-frequency decrease relationship was investigated. Five modes were considered while evaluating damage and frequency decrease of the tested specimens. The relationship between frequency decrease, stiffness degradation and damage level were presented while comparing with Unreinforced Brick Infill (URB) and Reinforced Infill wall with Bed Joint Reinforcement (BJR) on the base of natural vibration frequency.

• 대한기계학회논문집
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• 제18권7호
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• pp.1605-1617
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• 1994

Air-spring is widely used in vibration isolation to reduce the table vibration. When a disturbance is applied to a table, however, it starts virbrating with a low frequency, but has a large displacement due to the reacting force of air-spring. In this study, to solve the table vibration problem, an active vibration control device based on state feedback control using air-spring and proportional control valves was designed. This device can suppress the displacement of the isolation table within allowable range, even any kind of disturbances are applied to the table. Firstly, theoretical analysis of an air-spring isolator was done. Secondly, characteristics of the isolator was investigated via computer simulation and experiment. Finally, active control of air-spring isolator was tested using optimal(LQG) and fuzzy control algorithms was performed to show the effectiveness of the control schems.

• 한국소음진동공학회논문집
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• 제17권7호
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• pp.565-571
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• 2007

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by using experiment and simulation. Optimal design for a passive air spring can be obtained by tuning the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the active vibration isolation table with the better isolation performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.831-836
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• 2006

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by using experiment and simulation. Optimal design for a passive air spring can be obtained by tuning the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the active vibration isolation table with the better isolation performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.329-334
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• 2001

Recently, the high precision technology can not be developed continuously if we don't have anti vibration technology. Vibration isolation technology using an air spring and laminated robber bearing is widely used because it has excellent vibration isolation characteristics. We developed high precision vibration table with two good element(air spring and LRB) for semiconductor factory. Air Spring is used for isolating the vertical vibration and LRB is used for isolating the horizontal Vibration. As a result, It has D-Class degree in BBR-Criteria. In this paper, we talk about orifice characteristics in the self-damped air spring and design flow of the laminated robber bearing. The orifice characteristics is delicate shade of length and diameter. When we do experimentation to find orifice characteristics, length is fixed and diameter is changed. The orifice diameter is the wider and the air spring stiffness is the softer.

• 한국소음진동공학회논문집
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• 제21권9호
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• pp.858-867
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• 2011

As applying an active control technique to a pneumatic vibration isolation system, the settling time for the payload excitation could be remarkably reduced as well as the improvement of isolation performance for the ground vibration. Some previous researches were dealt with the settling time through the simulation or experiment but, the discussion on the simulation or experimental results including moving parts, such as a XY-stage, on the isolation table rarely exists. As considering the moving part, the dynamic model could be time varying system and in such a case the force imposed on pneumatic vibration isolation table could be described by inertial forces of moving parts according to Newton's 3rd law, the action and reaction law. In this paper, the simulation procedure of the 3-DOF active pneumatic vibration isolation system including moving parts by TDC(time delay control) technique is proposed and the effectiveness through simulation results are also shown.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.184-189
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• 2006

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by rising experiment and simulation. Optimal design for a passive air spring can be obtained by fluting the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the act ive vibration isolation table wi th the bet ter isolation performance.

• 한국지진공학회논문집
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• 제5권4호
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• pp.67-74
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• 2001

지진에 대한 구조물의 건전도는 내진설계에 의하여 많이 개선된 반면, 구조물 내부의 설비 및 중요 장비등에 대한 안정성은 최근에 관심을 가지게 되었다. 특히 국보급 문화재나 소장품은 그 가치에 비하여 지진에 대한 안전성이 고려되지 않은 것은 사실이다. 본 연구에서는 지진에 의하여 발생할 수 있는 내부 기기 및 문화재의 전도, 낙하를 방지하기 위한 면진 시스템을 개발하여, 본 장치에 대한 면진성능을 진동대 실험을 통하여 검증하였다. 본 면진 테이블은 전시물의 하부에 설치되어, 바닥판의 진동이 전시대에 전달되는 것을 차단하는 격리시스템이다. 면진성능시험 결과, 면진성능이 80-90%이며 면진테이블의 최대 스트로트내에서 안정적으로 거동하는 것으로 나타났다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.227-232
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• 2003

As the most precision equipment requiring very strict vibration environment are vulnerable to the surrounding vibration condition, they adapt the passive or active vibration isolation system. When it comes to the passive isolation system, the resonance of the isolation system causes excessive resonance response, and finally results in the degrade the equipment performance. This paper deals with the active control method to control this resonance induced response, and includes the experiment on the active control for controlling the resonance response on the table against the excitation of the same frequency with the natural frequency of the isolation system. The electromagnetic actuator was designed and the control effect was verified by the experiment. The experiment showed that the electromagnetic actuator is effective for controlling the low frequency isolation resonance response of the precision equipment.

• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.795-805
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• 2006

Tuned Liquid damper and Tuned Liquid Column are kind of passive mechanical damper which relies on the sloshing of liquid in a rigid tank for suppressing structural vibrations. TLD and TLCD are attributable to several potential advantages - low costs ; easy to install in existing structures : effective even for small-amplitude vibrations. In this paper, the shaking table experiments were conducted to investigate the characteristics of water sloshing motion in TLD (rectangular, circular) and TLCD. The parameter obtained from the experiments were wave height, base shear force and energy dissipation. The shaking table experiments show that the liquid sloshing relies on amplitude of shaking table and frequency of tank. The TLCD was more effective control vibration than TLD.