• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문초록집
• /
• pp.309.2-309
• /
• 2002

This paper is concerned with the development of the vibration isolation system using piezoelectric actuators and sensors. The active vibration absorber system consists of 4 pairs of PZT actuators bonded on aluminum plates making s- shaped device. Hence, the active system is directly connected to the passive system. The rubber attached to the end of the beam is connected to the upper base as a structural member. It allows bending thus maximizing the vertical movement generated by the piezoceramic actuators. (omitted)

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 춘계학술대회 논문집
• /
• pp.324-329
• /
• 2012

Isolation tables are widely used for precision equipments and their isolation performances have been usually expressed and evaluated by transsmissibility. However, transmissibility is a concept for 1-degree of freedom(DOF) system. In practice, isolation tables are supproted by more than 4 springs. Each spring is subjected to vertical and horizontal ground vibrations, and also the table has more than 1-DOF. Therefore, isolation tables should be treated as multi-input/multi-output(MIMO) system of which isolation performance is expressed by transmissibility matrix. However, the matrix is too complicated to be an index for a system. In this paper, maximum singular value of transmissibility matrx is suggested as a simple performance index of a MIMO isolation system. Physical meaning of singular value is explained using a simple a 2-DOF isolation table. Furthermore, maximum singular values of passive, 3-DOF active and 6-DOF active isolation tables are obtained through experiments, and their meaning are explained and compared with each other.

• 한국소음진동공학회논문집
• /
• 제16권3호
• /
• pp.307-312
• /
• 2006

In this study a vibration isolation system with the cradle-type support was designed so as to reduce the transient vibration due to positioning motion of the moving mass on worktable as well as to achieve the desired isolation efficiency on the floor vibration. The design procedure was performed in the two steps. The first step to select appropriate isolators to meet the isolation efficiency, and the second step is to reduce the transient vibration of the worktable by adopting the cradle-type support. After the application of the selected isolators with the cradle-type support to the system it was shown that the required vibration criterion(VC-D) was easily satisfied and that the undesirable transient vibration was reduced remarkably.

• 한국공간구조학회논문집
• /
• 제19권3호
• /
• pp.33-40
• /
• 2019

A seismic isolation system is one of the most effective control devices used for mitigating the structural responses due to earthquake loads. This system is generally used as a type of base isolation system for low- and mid-rise building structures. If the base isolation technique is applied to high-rise buildings, a lot of problems may be induced such as the movement of isolation bearings during severe wind loads, the stability problem of bearings under large compression forces. Therefore, a mid-story isolation system was proposed for seismic protection of high-rise buildings. Residence-commerce complex buildings in Korea have vertical irregularity because shear wall type and frame type structures are vertically connected. This problem can be also solved by the mid-story isolation system. An effective analytical method using super elements and substructures was proposed in this study. This method was used to investigate control performance of mid-story isolation system for residence-commerce complex buildings subjected to seismic loads. Based on numerical analyses, it was shown that the mid-story isolation system can effectively reduce seismic responses of residence-commerce complex tall buildings.

• 한국ITS학회 논문지
• /
• 제4권3호
• /
• pp.45-50
• /
• 2005

본 논문에서는 vertical coupling이라는 새로운 구조를 통해 구현한 광대역 rat race ring을 이용하여 광대역 단일 평형 다이오드 혼합기를 설계 및 구현하였다. RF주파수 범위는 $1.5{\sim}3$ GHz, LO의 주파수 범위는 $1.64{\sim}3.14$ GHz의 광대역 주파수 범위에서 140 MHz의 IF 주파수를 선택하였다. 입력되는 LO 신호가 2.74 GHz에서 6 dBm, RF의 입력 신호가 2.6 GHz에서 40 dBm일 때의 출력 포트(IF)에서의 변환손실은 7.5 dB와 30 dB의 RF와 LO의 우수한 격리도를 측정 결과에서 각각 나타내었다. $1.5{\sim}3$ GHz의 광대역 RF주파수 범위 내에서 평균 10 dB의 변환손실과 30 dB의 높은 RF와 LO 격리도, 45 dB의 LO와 IF 격리도를 측정결과에서 각각 나타내었다.

• 한국지진공학회논문집
• /
• 제8권5호통권39호
• /
• pp.79-89
• /
• 2004

본 연구에서는 원전기기의 내진안전성을 증가시키기 위해 면진장치를 적용한 기기의 진동대 실험을 수행하였다. 원전구조물과 유사한 진동수 특성을 가지는 실험모형을 제작하여 실험에 사용하였으며 구조물 내부의 기기를 모형화 하기 위하여 400kg의 강체를 사용하였다. 탁월주파수 특성이 상이한 3종류 지진파를 이용하여 진동대 실험을 수행하였다. 면진장치로는 마찰진자형 베어링(FPS)을 사용하였다. 입력지진의 최대가속도를 0.1g, 0.2g, 0.25g의 3단계로 변화시키면서 실험을 수행하였고 또한 1방향, 2방향 및 3방향 가진에 의한 거동을 분석하였다. 실험결과 지진파의 연직성분이 FPS의 면진성능에 영향을 미치는 것을 알 수 있었으며 펄스타입의 속도성분이 큰 근거리 지진인 경우 면진효과가 감소하는 것을 알 수 있었다.

• 한국공간구조학회논문집
• /
• 제8권6호
• /
• pp.49-57
• /
• 2008

지진에 의한 구조물의 응답을 저감시키기 위하여 다양한 면진장치가 사용되고 있으며 면진장치가 설치된 구조물은 고유주기가 길어져서 지진파의 탁월 주기를 벗어나게 된다. 대공간 구조물의 상부(지붕)구조인 트러스 아치는 하부구조인 기둥에 의하여 지지되는 경우가 있을 수 있다. 본 연구에서는 하부 기둥에 따른 면진 트러스 아치구조물의 거동을 분석하고자 한다. 면진장치를 대공간 구조물에 적용할 경우에 수평지진하중에 의하여 수평방향 지진응답이 저감되는 것은 물론 면진장치의 수직강성으로 인하여 수직응답도 현저하게 저감되는 것을 알 수 있었다. 하부의 기둥 강성이 큰 경우에 트러스 아치의 거동은 기둥 없이 트러스 아치가 지반에 직접 지지되는 트러스 아치의 거동과 유사하게 나타나고 있다. 또한 하부구조의 강성이 비교적 작은 대공간구조물에 면진장치를 적용할 경우에는 지진응답에 대한 우수한 제어 성능을 얻을 수 있을 것이다.

• Smart Structures and Systems
• /
• 제25권3호
• /
• pp.323-335
• /
• 2020

Magnetorheological elastomer (MRE), a smart material, is an innovative material for base isolation system. It has magnetorheological (MR) effect that can control the stiffness in real-time. In this paper, a new hybrid base isolation system combining two electromagnetic closed circuits and the roller bearing is proposed. In the proposed system, the roller part can support the vertical load. Thus, the MRE part is free from the vertical load and can exhibit the maximum MR effect. The MRE magnetic loop is constructed in the free space of the roller bearing and forms a strong magnetic field. To demonstrate the performance of the proposed hybrid base isolation system, dynamic characteristic tests and performance evaluation were carried out. Dynamic characteristic tests were performed under the extensive range of strain of the MRE and the change of the applied current. Performance evaluation was carried out using the hybrid simulation under five earthquakes (i.e., El Centro, Kobe, Hachinohe, Northridge, and Loma Prieta). Especially, semi-active fuzzy control algorithm was applied and compared with passive type. From the performance evaluation, the comparison shows that the new hybrid base isolation system using fuzzy control algorithm is superior to passive type in reducing the acceleration and displacement responses of a target structure.

• Steel and Composite Structures
• /
• 제52권1호
• /
• pp.1-14
• /
• 2024

This paper introduces a system allows for seismic isolation of the pallet from the rack in the down-aisle direction, occupies minimal vertical space (5 cm) and ±7.5 cm of deformation range. A conceptual model of the isolation system is presented, leading to a constitutive equation governing its behavior. A first experimental campaign studying the response of the isolation system's components was conducted to calibrate the parameters of its constitutive equation. A second experimental campaign evaluated the response of the isolation system with mass placed on it, subjected to cyclic loading. The results of this second campaign were compared with the numerical predictions using the pre-calibrated constitutive equation, allowing a double-blind validation of the constitutive equation of the isolation system. Finally, a numerical evaluation of the isolation system subjected to a synthetic earthquake of one component. This evaluation allowed verifying attributes of the proposed isolation system, such as its self-centering capacity and its effectiveness in reducing the absolute acceleration of the isolated mass and the shear load transmitted to the supporting beams of the rack.

• Earthquakes and Structures
• /
• 제27권1호
• /
• pp.57-67
• /
• 2024

To assess the seismic performance of Plate-Shell Integrated Concrete Liquid-Storage Structure (PSICLSS), a scaled test model was constructed. This model incorporated a hybrid isolation system, which combined shape memory alloy (SMA), lead-cored rubber isolation bearing (LRB) and sliding isolation bearing (SB). By conducting shaking table test, the dynamic responses of both non-isolated and hybrid-isolated PSICLSS were analyzed. The results show that the hybrid isolation system can effectively reduce the acceleration and displacement responses of the structure. However, it also results in an increase in local hydrodynamic pressure and liquid sloshing height. Under extreme earthquake action, the displacement of isolation layer is small. When vertical ground motion is taken into account, the shock absorption rate of horizontal acceleration decreases. The peak hydrodynamic pressure increases significantly, and the peak hydrodynamic pressure position also changes. The maximum displacement of isolation layer increases, the residual displacement decreases.