Development of high temperature drying system supported by AE for boxed heart heavy timber without check

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In wood drying, the sensing technology of the surface checks has not been established. Though the use of the AE method is experimentally tried in the wood drying, the research example in the heavy timbers does not especially include the testing example because the attenuation of the AE wave in wood is remarkable.In this research, proof of monitoring checks by AE was tried under assumption that the first check position was able to be specified by damaging by nailing. The center of the flat grain of the boxed-heart square timber was nailed, and AE of the nail was measured during drying. AE was generated regardless of the checks during steaming. But it was thought that the surface checks were able to be monitored because the surface checks were caused in the one that an increase in the AE generation for a short time was seen during drying afterwards.In monitoring internal checks of the boxed-heart square timber, the nail deeply drove at the position of 3cm from the edge of face and AE of the nail was measured because there was a feature had often generated like the diagonal from pith. AE was recognized as well as the measurement of the surface check during steaming though no internal check was generated. In the condition that internal checks occurred, increases in the AE generation were comparatively seen for a long term since a day after steaming. That is, it was guessed that internal checks would not occur in a short time at a time but progress little by little comparatively for a long time since middle term of drying.