Today, commercialized Hinoki cypress cubes are used for fragrance, humidification, and pillows in Korea. In this study, the sound absorption ability of Hinoki cypress (Chamaecyparis obtusa) cubes was examined. The three groups of Hinoki cypress cubes were prepared depending on their dimension (L: 9 × 9 × 9, M: 7 × 7 × 7, S: 4 × 4 × 4 mm). Their sound absorption coefficient was examined after filling 6, 8, 10, and 12 cm height in impedance tubes, respectively. Overall, the sound absorption ability depending on dimension was superior in the M group compared to the L and S groups. Also, as the filling height increased, the sound absorption capacity increased. In sum, noise reduction coefficients (NRC) of all Hinoki cypress cubes were 0.41-0.59. Thus, this research found that Hinoki cypress cubes have a sound-absorbing function.
Background: Due to coronavirus disease 2019 (COVID-19), world-wide face mask use is increasing exponentially. These face masks are difficult to recycle, and their accumulation contributes to enormous environmental threats. In this study, we hypothesize that the face mask can be reused as long as it retains its original structure, which will slow the environmental impacts. Materials and Methods: We selected common disposable surgical masks for this study and classified test conditions based on wear time and reuse method. After wearing the mask for 10 hours, we let it dry naturally in the shade for 14 hours. The specimens were measured by scanning electron microscope and capillary flow porometer. Results: The pore structure of the mask did not change when worn 4 times for 10 hours each time, and there was no significant pore structure change when impregnated with ethyl alcohol (purity 95%), treated with UV or steam, or run through a washing machine.
Conclusion:The pore structure of the surgical mask was not changed significantly after 40 hours of use. Surgical mask pore structure did not change significantly after treatment with ethyl alcohol, UV light, steam, or a washing machine.
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