• Smart Structures and Systems
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• 제24권1호
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• pp.37-52
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• 2019

Despite its success and wide application, base isolation system has been challenged for its passive nature, i.e., incapable of working with versatile external loadings. This is particularly exaggerated during near-source earthquakes and earthquakes with dominate low-frequency components. To address this issue, many efforts have been explored, including active base isolation system and hybrid base isolation system (with added controllable damping). Active base isolation system requires extra energy input which is not economical and the power supply may not be available during earthquakes. Although with tunable energy dissipation ability, hybrid base isolation systems are not able to alter its fundamental natural frequency to cope with varying external loadings. This paper reports an overview of new adventure with aim to develop adaptive base isolation system with controllable stiffness (thus adaptive natural frequency). With assistance of the feedback control system and the use of smart material technology, the proposed smart base isolation system is able to realize real-time decoupling of external loading and hence provides effective seismic protection against different types of earthquakes.

• Earthquakes and Structures
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• 제11권6호
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• pp.1077-1099
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• 2016

One of the main shortcomings in the current passive base isolation system is lack of adaptability. The recent research and development of a novel adaptive seismic isolator based on magnetorheological elastomer (MRE) material has created an opportunity to add adaptability to base isolation systems for civil structures. The new MRE based base isolator is able to significantly alter its shear modulus or lateral stiffness with the applied magnetic field or electric current, which makes it a competitive candidate to develop an adaptive base isolation system. This paper aims at exploring suitable control algorithms for such adaptive base isolation system by developing a close-loop semi-active control system for a building structure equipped with MRE base isolators. The MRE base isolator is simulated by a numerical model derived from experimental characterization based on the Bouc-Wen Model, which is able to describe the force-displacement response of the device accurately. The parameters of Bouc-Wen Model such as the stiffness and the damping coefficients are described as functions of the applied current. The state-space model is built by analyzing the dynamic property of the structure embedded with MRE base isolators. A Lyapunov-based controller is designed to adaptively vary the current applied to MRE base isolator to suppress the quake-induced vibrations. The proposed control method is applied to a widely used benchmark base-isolated structure by numerical simulation. The performance of the adaptive base isolation system was evaluated through comparison with optimal passive base isolation system and a passive base isolation system with optimized base shear. It is concluded that the adaptive base isolation system with proposed Lyapunov-based semi-active control surpasses the performance of other two passive systems in protecting the civil structures under seismic events.

• 한국전산구조공학회논문집
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• 제24권2호
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• pp.157-165
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• 2011

지진하중이 가해지는 구조물의 동적응답을 줄이기 위해서 면진장치가 널리 사용되고 있다. 근래에 들어서는 면진층의 변위를 증가시키지 않으면서도 면진된 구조물의 동적응답을 효과적으로 줄일 수 있는 스마트 면진시스템에 대한 연구가 활발히 이루어지고 있다. 이에 본 연구에서는 지진하중을 받는 아치구조물의 동적응답을 저감시키기 위하여 스마트 면진시스템을 적용하였고 제어성능을 검토하였다. 스마트 면진시스템을 구성하기 위하여 4kN 용량의 MR 감쇠기와 저감쇠 탄성 고무베어링을 사용하였다. 제안된 스마트 면진시스템의 제어성능을 검토하기 위하여 최적설계된 LRB와 지진응답 제어성능을 비교하였다. 이를 위하여 KBC2009 설계응답스펙트럼에 맞추어 생성한 인공지진파를 지진하중으로 사용하였다. 스마트 면진시스템의 MR 감쇠기를 제어하기 위하여 퍼지제어기를 사용하였으며, 다목적 유전자알고리즘을 이용하여 최적화하였다. 수치해석결과 스마트 면진시스템을 사용하면 LRB를 사용한 경우와 비교하여 면진층 변위와 아치구조물의 지진응답을 크게 줄일 수 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제31권6호
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• pp.586-594
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• 1999

To limit both the large displacement and acceleration response of the structure efficiently, the relationships between acceleration and displacement responses of the structure under several earthquakes are investigated for various horizontal stiffness of the base isolation system to determine the effective stiffness of the base isolation system in this paper. An example structure is a five-storey steel frame building as the primary structure and the secondary structures are assumed to be located on the fifth floor of the primary structure. Input motions used in the structural analysis are El Centre 1940, Taft 1952, Mexico 1985, San Fernando 1971 Pacoima Dam, and artificially generated earthquakes. The relationships of the absolute peak acceleration and the displacement at the top of the structure are calculated for various natural periods of base isolators under various earthquakes. The peak acceleration response of the fifth floor in the base isolated structure is significantly reduced by a factor of 2.1 through 6.25. Also, the relative displacement response of the floor to the base of the superstructure is very small. The results of this study can be utilized to determine the effective stiffness of the base isolation system.

• 한국지진공학회논문집
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• 제19권3호
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• pp.85-92
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• 2015

Response spectra of a building are made with a SDOF system taking into account a first mode shape, even though higher modes may affect on the dynamic responses of a high-rise building. A soft soil layer under a building also affects on the responses of a building. In this study, seismic responses of a MDOF system were investigated to examine the effects of higher modes on the response of a tall building by comparing them with those of a SDOF system including the kinematic interaction effect. Study was performed using a pseudo 3D finite element program with seven bedrock earthquake records downloaded from the PEER database. Effects of higher modes on the seismic responses of a tall building were investigated for base shear force and base moment of a MDOF system including story shear forces and story moments. Study results show that higher modes of a MDOF system contribute to a reduction of base shear force up to 1/4-1/5 of KBC and base moment. The effect of higher modes is more significant on the base shear force than on the base moment. Maximum story shear force and moment occurred at the top part of a building rather than at a base in the cases of tall buildings differently from short buildings, and higher modes of a tall building affected on the base forces making them almost constant at the base. A soft soil layer also affects some on the base shear force of a high-rise building independently on the soft soil type, but a soft soil effect is prominent on the base moment.

• 한국군사과학기술학회지
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• 제15권3호
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• pp.306-314
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• 2012

This paper proposes a new system to maximize efficiency of Air Base Protection Operations through the development of location identification software. The Wibro-based location identification system for Air Base Protection Force offers Blue Ground Force digitalized character message which is not exposed to enemy. Also, it is possible to automatically provide the location of Blue Ground Force to Air Base Ground Operations Center. The test result proves that this system is very helpful when Air Base Protection Force executes Air Base Protection Operations.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.89-94
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• 2010

The most important of rule-base system is the knowledge base that determines the power of rule-base system. The important form of this knowledge is how to descript kinds of rules. The Rule-Base System (RBS) has been using in many field that need reflect quickly change of business rules in management system. As far, when develop the Rule-Based System, we must make a rule engine with a general language. There are three disadvantage of in this developed method. First, while there are many data that must be processed in the system, the speed of processing data will become very slow so that we cannot accept it. Second, we cannot change the current system to make it adaptive to changes of business rules as quickly as possible. Third, large data make the rule engine become very complex. Therefore, in this paper, we propose the two important methods of raising efficiency of Rule-Base System. The first method refers to using the Relational database technology to process the rules of the Rule-Base System, the second method refers to a algorithm of according to Quine McCluskey formula compress the rows of rule table. Because the expressive languages of rule are still remaining many problems, we will introduce a new expressive language, which is Rule-Base Data Model short as RBDM in this paper.

• 한국정밀공학회지
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• 제18권10호
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• pp.45-52
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• 2001

This paper presents a study on the position tracking control of a robot system on the uncertain elastic base. The elastic bathe is a nonholonomic system but it can be changed into holonomic system, which is much easier to analyze, by modeling an elastic base as a virtual robot that has passive joints. Also, Jacobian operators, which represent the overall robot system including base movement, are defined and applied to the changed model. However, because base movements are not known, the exact Jacobian operators can＇t be estimated. The control algorithm proposed is that uses only Jacobians of a real robot as approximate Jacobian operators. Therefore the approximate Jacobian operators compensate the measured errors from external sensors. The proposed control strategy is evaluated by the simulation and experiment of a single-axis robot system on the elastic base.

• 전산구조공학
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• 제3권1호
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• pp.71-81
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• 1990

Base isolation system은 구조물의 기초하부에 설치되며 지진에 의한 구조물의 피해를 감소시켜 준다. 지금까지 많은 공학들에 의해 여러가지 base isolation system이 개발되었으나 실용화된 것은 1970년대에 laminated rubber bearing(LR type)이 개발되고서부터 였다. 최근에는 laminated rubber bearing밑에 미끄럼판을 둔 새로운 base isolation system(SR type)이 개발되었다. 본 연구에서는 isolation system과 구조물의 여러가지 성질에 따른 isolation효과에 대한 연구를 수행하였다. 이 연구의 결과, isolaion system은 지진하중이 작용할 때 건물에 발생하는 피해를 상당히 감소시킴을 알 수 있으며, isolaion system의 주기가 길어짐에 따라 isolation효과는 증가함을 알 수 있다. 그리고 건물의 높이가 증가함에 따라 isolation효과는 줄어든다는 것을 알 수 있다. SR type isolation system이 있는 건물에 지진하중이 작용할 때, 건물내부에서 발생하는 가속도와 층간변위, 그리고 전체변위는 LR type의 경우보다 작으므로 보다 효율적이라는 것을 알 수 있다.

• 제어로봇시스템학회논문지
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• 제5권1호
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• pp.54-61
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• 1999

Objective of the research is to put the vast and complex fault tracking knowledge of human experts in semiconductor production line into the knowledge base of computer system. We mined the fault tracking knowledge of domain experts(engineers of production line) for the construction of knowledge base of the expert system. Object oriented fact models which increase the extensibility and reusability have been built. The rules are designed to perform the fault diagnosis of the items in production device. We have exploited the evidence accumulation method to assign check priority in rules. The major contribution is in the overall design and implementation of the nile base and related facts of the expert system in object oriented paradigm for the application of the system in fault diagnosis in semiconductor production line.