정형조 교수

Bridge inspection using unmanned aerial vehicles (UAV) with high performance vision sensors has received considerable attention due to its safety and reliability. As bridges become obsolete, the number of bridges that need to be inspected increases, and they require much maintenance cost. Therefore, a bridge inspection method based on UAV with vision sensors is proposed as one of the promising strategies to maintain bridges. In this paper, a crack identification method by using a commercial UAV

In this paper, a new energy harvesting system based on wind energy is investigated. To this end, the characteristics and mechanisms of various aerodynamic instability phenomena are first examined and the most appropriate one (i.e. wake galloping) is selected. Then, a wind tunnel test is carried out in order to understand the occurrence conditions of the wake galloping phenomenon more clearly. Based on the test results, a prototype electromagnetic energy harvesting device is designed and manufact

This paper examines the ASCE first generation benchmark problem for a seismically excited cable-stayed bridge, and proposes a new semiactive control strategy focusing on inclusion of effects of control-structure interaction. The subject of the ASCE benchmark problem is a cable-stayed bridge in Cape Girardeau, Missouri, for which construction is expected to be completed in 2003. The goal of the benchmark study is to provide a testbed structure on which researchers can systematically compare and e

Semiactive control systems have received considerable attention for protecting structures against natural hazards such as strong earthquakes and high winds, because they not only offer the reliability of passive control systems but also maintain the versatility and adaptability of fully active control systems. Among the many semiactive control devices, magnetorheological (MR) fluid dampers comprise one particularly promising class. In the field of civil engineering, much research and development

This paper proposes an innovative building-integrated wind turbine (BIWT) system by directly utilizing the building skin, which is an unused and unavailable area in all conventional BIWT systems. The proposed system has been developed by combining a guide vane that is able to effectively collect the incoming wind and increase its speed and a rotor with an appropriate shape for specific conditions. To this end, several important design issues for the guide vane as well as the rotor were thoroughl

This paper investigates the effectiveness of the MR damper-based control systems for seismic protection of base-isolated building structures employing some semi-active control algorithms, such as the modified clipped-optimal control, the maximum energy dissipation, the modulated homogeneous friction, and fuzzy logic-based control algorithms, by examining the Phase I smart base-isolated benchmark building problem. The results of the numerical simulations showed that most of the control systems co

This article investigates a smart base-isolation system using magnetorheological (MR) elastomers, which are a new class of smart materials whose elastic modulus or stiffness can be adjusted depending on the magnitude of the applied magnetic field. The primary goals of this study are to develop a smart base-isolation model that represents the field-dependent dynamic behaviors of MR elastomers, to design and construct a scaled smart isolation system and a scaled building structure for a proof of c

This paper proposes an electromagnetic energy harvesting system, which utilizes the wind-induced vibration of a stay cable, and investigates its feasibility for powering a wireless sensor node on the cable through numerical simulations as well as experimental tests. To this end, the ambient acceleration responses of a stay cable installed in an in-service cable-stayed bridge are measured, and then they are used as input excitations in cases of both numerical simulations and experimental tests to

Energy harvesting systems convert ambient energy from environment such as vibration, sunlight, wind, temperature gradient, etc. into electrical energy. Among several ambient energy sources, wind energy can be considered as one of the most promising sources because of its attractive features such as efficiency and economic merit. However, if an ordinary type of wind turbine is used for providing the electricity to low-power equipments (e.g., light poles, wireless sensors for structural health mon

Accurate displacement sensing or estimation is an important task for reliably assessing the condition of civil infrastructure such as bridges and buildings, because the structural displacement describes the behavior of a structure and indicates structural safety according to the design limit. However, it is difficult to directly measure the displacement of a bridge structure due to the inaccessibility of a reference point especially when bridges are built over a highway, a river or the sea. As a

In this study, the feasibility of using micro-wind turbines to power wireless sensors on a cable-stayed bridge is comprehensively investigated. To this end, the wind environment around a bridge onto which a turbine is installed is examined, as is the power consumption of a wireless sensor. Feasible alternators and rotors are then carefully selected to make an effective small wind generator (known as a micro-wind turbine). Using the three specially selected micro-wind turbines, a series of experi