• Smart Structures and Systems
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• 제4권1호
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• pp.85-98
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• 2008

In this paper, excitation systems using a linear mass shaker (LMS) and an active tuned mass damper (ATMD) are presented to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop functions are used to prevent the actuator from exciting unexpected modal responses and an initial transient response and thus, to minimize the error between the wind and actuator induced responses. The analyses results from a 76-story benchmark building problem for which the wind load obtained by a wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately reproduce the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.

• Smart Structures and Systems
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• 제14권3호
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• pp.347-365
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• 2014

The main objective of this paper is to develop an innovative methodology for the vibration suppression control of the multiple degrees-of-freedom (MDOF) flexible structure. The proposed structure represented in this research as a clamped-free-free-free truss type plate is rotated by motors. The controller has two loops for tracking and vibration suppression. In addition to stabilizing the actual system, the proposed feedback control is based on a genetic algorithm (GA) to seek the primary optimal control gain for tracking and stabilization purposes. Moreover, input shaping is introduced for the control scheme that limits motion-induced elastic vibration by shaping the reference command. Experimental results are presented, demonstrating that, in the control loop, roll and yaw angles track control and elastic mode stabilization. It was also demonstrated that combining the input shaper with the proportional-integral-derivative (PID) feedback method has been shown to yield improved performance in controlling the flexible structure system. The broad range of problems discussed in this research is valuable in civil, mechanical, and aerospace engineering for flexible structures with MDOM motion.

• Smart Structures and Systems
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• 제4권2호
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• pp.183-194
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• 2008

An important historical monument of Cyprus is an aqueduct that was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the case-study monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). Detailed drawings of the aqueduct obtained from the Department of Antiquities of Cyprus have been used for the development of a computational model. The model was fine-tuned through the measurement of the dynamic characteristics of the aqueduct using forced and ambient vibrations. It should be noted that measurement of the dynamic characteristics of the structure were performed twice in a period of three years (June of 2004 and May of 2007). Significant differences were noted and they are attributed to soil structure interaction effects due to seasonal variations of the water-level in a nearby salt-lake. The system identification results for both cases are presented here. This monument was used to test the effectiveness of shape memory alloy (SMA) pre-stressed devices, which were developed during the course of the project, in protecting it without spoiling its monumental value.

• Smart Structures and Systems
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• 제26권5호
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• pp.545-558
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• 2020

A design method of a Multiple Tuned Mass Damper (MTMD) system is presented for wind induced vibration control of a cable-supported roof structure. Modal contribution analysis is carried out to determine the dominating modes of the structure for the MTMD design. Two MTMD systems are developed for two most dominating modes. Each MTMD system is composed of multiple TMDs with small masses spread at multiple locations with large responses in the corresponding mode. Frequencies of TMDs are distributed uniformly within a range around the dominating frequencies of the roof structure to enhance the robustness of the MTMD system against uncertainties of structural frequencies. Parameter optimizations are carried out by minimizing objective functions regarding the structural responses, TMD strokes, robustness and mass cost. Two optimization approaches are used: Single Objective Approach (SOA) using Sequential Quadratic Programming (SQP) with multi-start method and Multi-Objective Approach (MOA) using Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The computation efficiency of the MOA is found to be superior to the SOA with consistent optimization results. A Pareto optimal front is obtained regarding the control performance and the total weight of the TMDs, from which several specific design options are proposed. The final design may be selected based on the Pareto optimal front and other engineering factors.

• Advances in Computational Design
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• 제2권3호
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• pp.211-223
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• 2017

This research presented a numerical and experimental study on the seismic performance of first-generation base-isolated and fixed-base nuclear power plants (NPP). Three types of the base isolation system were applied to rehabilitate the first-generation nuclear power plants: frictional pendulum (FP), high-damping rubber (HDR) and lead-rubber (LR) base isolation. Also, an Excel program was proposed for the design of the abovementioned base isolators in accordance with UBC 97 and the Japan Society of Base Isolation Regulation. The seismic assessment was performed using the pushover and nonlinear time history analysis methods in accordance with the FEMA 356 regulation. To validate the adequacy of the proposed design procedure, two small-scale NPPs were constructed at Universiti Teknologi Malaysia's structural laboratory and subjected to a pushover test for two different base conditions, fixed and HDR-isolated base. The results showed that base-isolated structures achieved adequate seismic performance compared with the fixed-base one, and all three isolators led to a significant reduction in the containment's tension, overturning moment and base shear.

• Composites Research
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• 제19권3호
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• pp.43-49
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• 2006

In this paper, a long gauge Fiber Bragg Grating (FBG) sensor system is described and long gauge FBGs are well-suited for measuring the upper parts of the bridge piers under the extremely severe movement conditions. In the experiments, we used more than 30m long FBG sensors to measure the movement of top part of the bridge piers which are separated from the main bridge by cutting the decks. With the actuator, the deck and girders were pushed and released. We checked the movement of the top of the pier while releasing the pressure of the actuator with the long gauge fiber sensor. In order to measure the movement of the upper part of the pier, the reference point must be outside of the pier. Using the optical fiber sensors, one end of the sensor is attached to the top of the pier and the other end is attached to the bottom of the next pier. The fiber sensors showed good response to the release loading and we could calculate the movement of the top part of the pear.

• Smart Structures and Systems
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• 제19권5호
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• pp.523-538
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• 2017

A series of field vibration tests are conducted on the Runyang Suspension Bridge during both the construction and operational stages. The purpose of this study is devoted to the analysis of the dynamic characteristics of the suspension tower. After the tower was erected, an array of accelerometers was deployed to study the evolution of its modal parameters during the construction process. Dynamic tests were first performed under the freestanding tower condition and then under the tower-cable condition after the superstructure was installed. Based on the identified modal parameters, the effect of the pile-soil-structure interaction on dynamic characteristics of the suspension tower is investigated. Moreover, the stiffness of the pile foundation is successfully identified using a probabilistic finite model updating method. Furthermore, challenges of identifying the dynamic properties of the tower from the coupled responses of the tower-cable system are discussed in detail. It's found that compared with the identified results from the freestanding tower, the longitudinal and torsional natural frequencies of the tower in the tower-cable system have changed significantly, while the lateral mode frequencies change slightly. The identified modal results from measurements by the structural health monitoring system further confirmed that the vibrations of the bridge subsystems (i.e., the tower, the suspended deck and the main cable) are strongly coupled with one another.

• 한국전자통신학회논문지
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• 제12권5호
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• pp.865-872
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• 2017

최근 사물인터넷시대를 맞이하여 센서와 컨트롤 기술, 모바일 어플리케이션, 네트워크 트래픽, 빅 데이터의 관리와 분석, 클라우드 컴퓨팅의 성장에 따라 새롭게 급성장하고 있는 스마트 홈 분야를 중심으로 하드웨어 장치에 대한 요구가 갈수록 높아지고 있다. 하드웨어 시스템의 지속 가능한 발전을 유지하기 위해서는 시스템의 업데이트를 필요 하고, 또한 하드웨어장치는 데이터 수집할 뿐만 아니라 복잡한 데이터(음성, 이미지 등)의 실시간 처리 시에 절대적으로 필요하기 때문이다. 본 논문에서는 각기 다른 운영체제하에 있는 하드웨어의 동시 제어 및 통신방식을 해결하고자 브리지방식으로 두 가지 운영체제내의 하드웨어 장치를 일체식 구조로 합치면서 제어 및 통신방식이 간단하게 되는 방법을 제시한다. 이를 위하여 제안된 일체형 하드웨어와 클라우드 서버 연결되는 클라우드 제어 시스템에 대한 성능평가 수행결과와 앞으로 사물인터넷 스마트 홈 분야에서 연구되어야 할 주요 방향에 대하여 기술하였다.

• 한국멀티미디어학회논문지
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• 제15권3호
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• pp.388-397
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• 2012

최근 웹 기반 서비스에서 각광받는 분야 중 하나는 SNS로 불려지는 "인적 관계 서비스"이다. 이들의 관계를 표현하는 관계 지도 서비스는 오프라인 현실과 연동된 직관적인 자료이기 때문에 사용자에게 정보를 더 쉽고 시각적으로 전달해 줄 수 있다. 과거의 지도 서비스가 주로 물리적 현실 정보를 담고 표현하는 것이었다면 오늘날 지도는 실제 세계를 담는 단순한 검색 플랫폼을 넘어 사회관계를 표현하고 커뮤니케이션하는 새로운 플랫폼으로 진화하고 있다. 본 논문에서는 온라인 지도 서비스의 구조를 기반으로 스케치맵을 활용한 스마트 소셜 그리드 시스템을 제안한다. 본 시스템은 다양한 SNS를 위한 표준 인터페이스 제공, 확대된 소셜 그리드를 통한 인맥 네트워크 구성 시 거버넌스 허브 툴로의 활용, 여타 SNS와 연계한 매쉬업 소프트웨어와의 브리지 역할, 소셜 그리드 데이터를 재생산하도록 하는 사용자 환경 구축, 향상된 탐색 기술을 통한 보다 빠른 서비스 구축 등의 특징을 갖는다.

• 한국항행학회논문지
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• 제21권1호
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• pp.126-131
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• 2017

본 논문은 오래된 옹벽과 같은 건축물이나 잠재적 위험을 내재한 건설 및 토목 구조물 등에 부착 가능한 블루투스 비콘 센서 노드를 활용하여 위험감지 및 대피/대처 서비스를 제공해줄 수 있는 스마트 안전 계측 시스템을 설계한다. 제안한 시스템은 블루투스 비콘을 활용하여 비콘이 설치된 지점의 가속도, 자이로, 지자계, 압력/고도, 온도/습도 등의 다양한 센서 데이터를 전송할 수 있으며 이러한 데이터를 활용하여 위험 감지, 예측, 경고 등의 다양한 서비스에 활용할 수 있다. 제안한 시스템의 실효성을 검증하기 위해 필드 테스트를 수행하였으며 옹벽의 변위값이 허용변위 38.5 mm 내에 존재한다는 것을 확인하였다.