In this study, an electrophoresis test was carried out to measure the diffusion coefficient of chloride ions in a short period of time for the purpose of improving the durability of precast concrete. In addition, similar experiments were conducted to verify the applicability to the repair material of the concrete cross-sectional defect and the fixing part for connection. As a result, we were able to confirm the effect of suppressing the permeation of chloride ions by adding a salt damage-resistant admixture to concrete and repair materials. The salt damage resistant admixture can be expected to improve the salt damage resistance performance of not only concrete but also repair materials. However, the addition of expansive materials makes the internal structure of concrete looser and reduces resistance to salt damage. In addition, it was found that electrophoresis inspection is useful in shortening the inspection time compared to the conventional sodium chloride solution immersion inspection.

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The 2016 Kumamoto earthquake caused extensive damage to road bridges in mountainous areas, it needs to be restored quickly and temporarily, and it is necessary to take measures to prevent the main structure from sustaining serious damage. In this study, it proposes a structure that absorbs energy when the abutment moved and pushed the main girder. It is set at the tip end of main girder. In this paper, the method is to avoid damage to the main structure by causing partial damage at girder ends. The method was to reduce the stiffness in a certain location to cause local buckling, and a nonlinear analysis was performed using the stiffness reduction as a parameter. The results of an analysis to confirm the effectiveness of the method are shown.

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A questionnaire survey on indirect speech requests conducted by Hirakawa was analyzed using Item Response Theory (IRT) applying Bayesian statistical modeling. From the knowledge of both the characteristics of the respondents and the characteristics of the question items, it is found that the characteristics of the question items are the cause of the bimodal distribution of respondents’ tendency to interpret the “interpretation of the request”. Also Bayesian IRT appears to offer benefits for scale design.

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As the working-age population continues to decline in Japan, there is a demand for labor-saving operations. Furthermore, recent developments in data communication and AI technology are making it possible to do things that were previously impossible. Therefore, DXNP, one of the Kumamoto National College of Technology research groups, is conducting research and educational activities using AI, IoT, and DX. This paper reports on the activities carried out from 2021 to 2022.

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