An AE method is an effective technique that can inspect corrosion damage of tank bottom plates to prevent leakage accidents of oil storage tanks. However, a correlation between AE signals and the corrosion behavior for bottom plates is not fully clarified. In this study, the authors considered that the corrosion regions in bottom plates become a strong acid environment by chloride ions as shown our previous work. The correlation between the AE signals and the corrosion behavior with a potentiostat for test pieces was examined in the environment. The polarization resistance was measured with an AC impedance method using a frequency response analyzer. It was clear that the polarization resistance indicated the corrosion rate for a test pieces in the experiments. While measuring the AE signals, the corrosion rate was monitored with a test piece. As a result, the AE signal showed the good correlation with the corrosion rates of the test pieces.
As interest in overall safety issues including natural disasters and living safety accidents is rising, preparing countermeasures against these problems has emerged as an important issue. Up to the present, mostly the government-initiated safety measures have been established and the system is such that safety service or safety information is provided unilaterally for the people. However, as questions as to its effectiveness are raised, demand for preparation of diverse forms of alternatives is increasing. Recently, breaking away from the government-led forms, the resident participation types of policies and safety improvement projects are attempted as part of the vitalization of citizen participation. Accordingly, the necessity to objectively and statistically investigate and analyze the residents'feeling effects such as feeling degree about the safety against disasters in the residential regions, the necessity of and the participation in the projects has been raised. In this research, through the questionnaire survey on 1,277 residents living in 20 places of the 2015 safety community projects, the effects of the projects such as the safety feeling degree of the residents of the applicable regions, the necessity of the detailed projects and participation intention, resident communities'disaster prevention capabilities (disaster risk awareness state, evacuation guidance abilities, the degree of autonomous preparation for evacuation, disaster and safety community activities, the degree of residents'participation, surveillance and security readiness, information delivery readiness) were analyzed. Through this, the items and the system of the analysis of the effectiveness of the safe community building projects were proposed and it is expected that this will be utilized not only in these projects but also similar projects.
Structural health monitoring (SHM) is a new technology that has been increasingly evaluated by the industry as a potential approach to improve the cost and ease of structural inspection. Piezoelectric smart active layer (SAL) sensor was fabricated to verify the applicability of finding cracks and conducting source location in a various materials. A crack detection and source location works were done in three kinds of test condition such as aluminum plates with crack for patch type SAL sensor, a smart airplane with embedding SAL sensor, and a concrete beam with real crack for practical application. From this experimental study, the evaluation algorithm for the arrival time delay and decrease of signal amplitude was suggested in this paper. Consequently, it was found that the SAL sensor and detection algorithm developed in this study can be effectively used to detect and monitor damages in the both existing structures and new designed smart structures.
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