As researchers continue to explore wireless sensors for use in structural monitoring systems, validation of field performance must be done using actual civil structures. In this study, a network low-cost was installed the Geumdang Bridge, Korea monitor bridge response truck loading. Such installations allow quantify accuracy and robustness systems within complex environment encountered field. total, 14 were concrete box girder span Bridge record acceleration responses forced vibrations...

Tidal current energy is a renewable that has the advantage of being predictable by generating power using periodic tidal movements. Because converter system installed underwater, maintenance costs are high, and systematic review various factors must be performed in advance. In this study, an integrated load analysis was to blade pitch control problem system. The impact on performance analyzed situations where angle adjustment not possible. It confirmed when fixed, fluctuation range increases...

In this paper, several modal identification techniques for output-only structural systems are extensively investigated. The methods considered the power spectral method, frequency domain decomposition Ibrahim time eigensystem realization algorithm, and stochastic subspace method. Generally, method is most widely used in practical area, however, other may give better estimates particularly cases with closed modes and/or large measurement noise. Example analyses were carried out on typical...

In recent years, the wind energy has played an increasingly important role in national sector of many countries. To harvest more electric power, turbine (WT) tower structure becomes physically larger, which may cause risks during long-term operation. Associated with great development WT projects, number accidents related to large-scaled also been increased. Therefore, a structural health monitoring (SHM) system for structures is needed ensure their safety and serviceability operational time....

The coating is applied to prevent corrosion on the surface of ships or marine structures, and thickness affects its anti-corrosion effect. As a result, non-destructive testing (NDT) required measure thickness, ultrasonic NDT convenient quick way underwater coatings. However, offshore coating’s energy attenuation absorption rates are high, pulse echo test difficult, environment harsh. Because high attenuation, distance optimal water delay line designed based reflection coefficient vertically...

A baseline model is essential for long-term structural performance monitoring and evaluation. This study represents the first effort in applying a neural network-based system identification technique to establish update finite element of an instrumented highway bridge based on measurement its traffic-induced vibrations. The network approach particularly effective dealing with large-scale structure by limited number sensors. In this study, sensor systems were installed two bridges extensive...

A vibration-impedance-based monitoring method is proposed to predict the loss of prestress forces in prestressed concrete (PSC) girder bridges. Firstly, a global damage alarming algorithm using change frequency responses formulated detect occurrence PSC girders. Secondly, local detection electro-mechanical impedance features selected identify prestress-loss tendon and anchoring members. Thirdly, prediction natural frequencies estimate extent Finally, feasibility experimentally evaluated on...

To study the wet natural frequency (in water) and dry air) of a tidal current turbine, we conducted two-year measurement campaign by deploying full-scale prototype system. In this article, theoretical model is developed validated with measurements. It reveals measured system could approach half that one. The measurements also show inflow turbulence very important in excitation resonances can lead to failure. We briefly discuss how varies over long period.

As global energy consumption continues to increase, the negative impact of warming also grows. Therefore, eco-friendly policy is being established all over world. Korea’s problems are further complicated by country’s high dependence on sourced overseas. Korean evolving rapidly address these problems. Korea has begun phase out nuclear power and focusing developing new sources renewable energy. So there been substantial interest in development ocean Of technologies, tidal current closest...

Coatings play a crucial role in protecting ships and marine structures from corrosion extending their service life. The reliability of these coatings depends on proper maintenance, which turn, relies the application reliable diagnostic techniques. Non-destructive testing (NDT) techniques are useful material diagnostics, such as detecting debonded zone water. However, challenging access environment ocean, high attenuation characteristics itself add too many technical challenges. In this...

Interfacial bond properties of six different epoxy resins used to coat submerged concrete structures were investigated. Test variables included coating type, equipment, and underwater curing time. Coating thickness pull-off strength measured using commercially available test equipment. varied greatly depending on the manufacturer. The standard (control) equipment positively influenced compared other effect time was not significant within range 24 72 h. Lastly, some important considerations...

There is a large risk of damage, triggered by harsh ocean environments, associated with offshore structures, so structural health monitoring plays an important role in preventing the occurrence critical and global failure from such damage. However, obstacles, as applicability field increasing calculation costs complexity, remain for real-time structure offshore. Therefore, this study proposes comparison cosine similarity sensor data to overcome challenges. As target, method uses rate changes...

Ultrasonic non-destructive analysis is a promising and effective method for the inspection of protective coating materials. Offshore exhibits high attenuation rate ultrasonic energy due to absorption pulse echo testing becomes difficult small amplitude second from back wall layer. In order address these problems, an advanced signal has been proposed. An delay line was applied A short-time Fourier transform (STFT) waveform implemented measure thickness state bonding The material estimated by...

Monopiles have been most widely used for supporting offshore wind turbines (OWTs) in shallow water areas. However, multi-member lattice-type structures such as jackets and tripods are also considered good alternatives to monopile foundations relatively deep areas with depth ranging from 25-50 m owing their technical economic feasibility. Moreover, jacket popular the oil gas industry a long time. several unsolved issues still persist utilization of OWTs; these problems include...

A thin layer of protective coating material is applied on the surface offshore concrete structures to prevent its degradation, thereby extending useful life structures. The main reasons for reduction in capability layers are loss adhesion and flattening wall. Usually, state monitored setting water immersion using ultrasonic inspection methods, method still needs improvement terms speed accuracy. In this study, pulse echo was used a test coated specimens, continuous wavelet transform (CWT)...