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The interdigital transducer–based scanning laser Doppler vibrometer has recently been introduced to efficiently generate the symmetric mode for damage detection of shallow defects in thick plates. To measure shallow defects in a carbon steel plate, the excitation frequency is optimized based on the analysis of wavenumber sensitivity and degree of separation between modes. Even though the interdigital transducer–based scanning laser Doppler vibrometer method using continuous excitation is a promising method for visualizing defects in plate-like structures, the interdigital transducer has to be coupled to media, such as oil or water, to minimize the variation in acoustic impedance between the lead zirconium titanate and the plate-like structures. In this study, we develop a dry-coupled interdigital transducer–based scanning laser Doppler vibrometer system for the detection of shallow defects in a plate to facilitate easy mounting and demounting from the plate. To verify the proposed dry-coupled interdigital transducer–based scanning laser Doppler vibrometer, plates with four and eight different depth defects are introduced, and it is demonstrated that the defects in thick plates measured by dry-coupled interdigital transducer–based scanning laser Doppler vibrometer are visualized compared to those measured by interdigital transducer–based scanning laser Doppler vibrometer.

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This study was conducted to investigate the effects of walking in the healing forests for short breaks on mood state, quality of life and stress reduction of hospital workers. For the study, 56 employees from Chungbuk University Hospital participated in the forest walks connected to the hospital using a short break three times a week for 20 minutes each for three weeks. The Korean Version of Profile of Mood States (K-POMS) and the Korean Occupational Stress Scale (KOSS-SF) were used as validated measurement tools to evaluate changes in mood state and job stress. A 5-point Likert scale was used for assessment of quality of life among employees. The results of the questionnaire were analyzed by paired t-test. As a result, tension, anger, confusion, and fatigue in mood state categories were decreased significantly and vigor was significantly increased after forest walks. Total mood disturbance was also decreased significantly. Quality of life for hospital workers was significantly improved after forest walks. In terms of job stress, average score of stress was significantly decreased after forest walks and especially stresses from the organizational system and improper reward were significantly decreased. The results of this study proved talking a short walk in the healing forests during breaks in daily work hours has a positive effect on mood state and life quality improvements and job stress reduction in hospital workers.