Papers by Author: Seung Hee Park

Abstract: This paper presents novel structural health monitoring techniques for critical members of civil structures using electro-mechanical impedance sensors. The basic concept of this technique is to monitor critical locations of a structure for changes in structural impedance that would indicate imminent damage. In this paper, principal hardware and software issues on this topic are reviewed. An active sensing node incorporating on-board microprocessor and radio frequency telemetry is introduced in a sense of tailoring wireless sensing technology to the impedance method. A data compression algorithm using a principal component analysis is embedded into the on-board chip of the active sensing node. Finally, a method for compensating the temperature effects on the impedance measurements using cross-correlation analysis with effective frequency shifts is presented.

Abstract: This paper presents a feasibility study of an impedance-based damage detection technique using PZT (Lead-Zirconate-Titanate) patches for real-time health monitoring of concrete structures. The PZT patches are used to detect progressive surface damage on a plain concrete beam. Both experimental and analytical studies are carried out. For damage quantification, root-mean square deviations (RMSD) before and after damage are used as a damage indicator.

Abstract: This paper presents a non-destructive evaluation (NDE) technique for detecting damages on a jointed steel plate on the basis of the time of flight and wavelet coefficient, obtained from wavelet transforms of Lamb wave signals. Probabilistic neural networks (PNNs) and support vector machines (SVMs) were applied for pattern classification. In this study, the applicability of the PNNs and SVMs was investigated for the damages in and out of the Lamb wave path. It has been found that the present methods are very efficient in detecting the damages simulated by the loose bolts on the jointed steel plate.