Mokuzai Gakkaishi
Online ISSN : 1880-7577
Print ISSN : 0021-4795
ISSN-L : 0021-4795
Volume 68, Issue 1
Displaying 1-6 of 6 articles from this issue
Mini review
  • Atsushi Yamada
    2022 Volume 68 Issue 1 Pages 1-7
    Published: January 25, 2022
    Released on J-STAGE: January 29, 2022
    JOURNAL FREE ACCESS

    In Hokkaido, 1.38 million m3 of woody biomass is annually used as energy at 2019. More than half (0.72 million m3) is used in large-scale woody biomass power plants by FIT (Feed-in Tariff), but carbon-neutral woody biomass energy use is expected to continue to grow in demand. In this review, I introduced the status of efforts in Hokkaido on moisture content reduction, pellet fuel, and torrefaction to improve the fuel quality of woody biomass fuel, and research on the construction of new supply chains and biorefinery.

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CategoryI
  • Influence on the bearing strength and stiffness of wood
    Shinya Tsubata, Shunsuke Sakai, Soichi Tanaka, Takeshi Morita, Takayuk ...
    2022 Volume 68 Issue 1 Pages 8-16
    Published: January 25, 2022
    Released on J-STAGE: January 29, 2022
    JOURNAL FREE ACCESS

    This study deals with the thermo-softening behavior of wood under the combined stresses in the drift pin joints of timber buildings. The purpose of this paper was to clarify the influence of thermal softening of wood on the bearing strength and stiffness, which was required to estimate the performance of the joints. The relations of bearing strength and stiffness to moisture content (MC) and temperature of wood samples were evaluated. The bearing test was conducted for the MC-conditioned sample by using the testing machine with the thermo-hygrostat. Both bearing strength and stiffness decreased with increasing MC and temperature, or with the promotion of the thermal softening. The decrease in both the strength and the stiffness in the longitudinal direction was larger than that in the transverse direction.

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  • Miho Shinozaki, Yuko Fujiwara, Yoshiyuki Yanase, The late Tsuyoshi Yos ...
    2022 Volume 68 Issue 1 Pages 17-25
    Published: January 25, 2022
    Released on J-STAGE: January 29, 2022
    JOURNAL FREE ACCESS

    This study describes a new parameter that can show the degree of decay of a sample, although its mass and/or density when it was sound are unknown. Small blocks of Japanese cedar (Cryptomeria japonica) were exposed to Fomitopsis palustris for an increasing time period ranging from one to seven weeks. A microfocus X-ray computed tomography (CT) system was used to observe the cross-section of the dried samples. The tracheids were arranged in linear radial files for sound or minor decayed (less than 5% mass loss) wood, and for decayed wood (more than 5% mass loss) the arrangement was curved. The degree of curvature increased with increasing mass loss of specimens. A two-dimensional fast Fourier transform was performed on each CT image and an amplitude spectrum image was obtained. The spectrum peak width in the R-direction of the decayed samples was wider than that in the sound and minor decayed samples. This main feature was quantified as a new parameter that corresponds to the mass loss (r = 0.82) and shear strength (r = -0.75).

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  • Tomonori Sato, Kenji Uehara, Shinji Kudo, Ikuko Sakaki, Jun-ichiro Hay ...
    2022 Volume 68 Issue 1 Pages 26-35
    Published: January 25, 2022
    Released on J-STAGE: January 29, 2022
    JOURNAL FREE ACCESS

    Disposition of the waste sawdust substrate from sawdust-based cultivation of shiitake mushrooms (Lentinula edodes) is an important issue. In this study, we evaluated the physiological activity in the water extracts of waste sawdust substrate which had been extracted by the two-step hot/hot-compressed water percolation. The 180°C water extract of waste sawdust substrate contained some isoprenoid and high amounts of polyphenol. Additionally, high antioxidant activity was found in the 180°C water extract of the waste sawdust substrate in in vitro experiment (DPPH scavenging activity) and the human keratinocyte, HaCaT. This study suggested that the two-step hot/hot-compressed water percolation elutes the antioxidant components in the 180°C fraction from the waste sawdust substrate.

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CategoryII
  • Influence of species and moisture content
    Wataru Ishihara, Yasuhiro Kawaai, Ryuya Takanashi, Junko Miyazaki, Yos ...
    2022 Volume 68 Issue 1 Pages 36-42
    Published: January 25, 2022
    Released on J-STAGE: January 29, 2022
    JOURNAL FREE ACCESS

    In order to investigate the rolling shear strength of CLT with Japanese softwood species, we carried out the rolling shear test by compression method with four major Japanese softwood species (Japanese cypress (Chamaecyparis obtusa), Japanese larch (Larix Kaempferi), Japanese cedar (Cryptomeria japonica) and Sakhalin fir (Abies sachalinensis)). In addition, in order to determine the effect of moisture content on rolling shear strength, the test specimens were humidity-controlled under three different humidity environments (40% RH, 65% RH, and 80% RH at 20°C). Results from the tests were as follows: (1) the rolling sheer strength was higher in the order of Japanese cypress, Japanese larch, Japanese cedar and Sakhalin fir, (2). There was no significant difference in the rolling shear strength due to the difference in moisture content. (3) There were correlations between the rolling shear strength and the air-dried density of laminae in Japanese cypress and Japanese cedar. However, there were no correlations between the rolling shear strength and the air-dried density of laminae in Japanese larch and Sakhalin fir.

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  • Kojiro Nishimiya, Takeshi Teruya, Tatsushi Haneji, Shingo Taniguchi
    2022 Volume 68 Issue 1 Pages 43-52
    Published: January 25, 2022
    Released on J-STAGE: January 29, 2022
    JOURNAL FREE ACCESS

    Sanshin is a traditional Okinawan musical instrument and it has been thought that the sao (neck) is the most important part for the timbre by the craftsman and the players. However, scientific research for the woods which are used for sao has not been conducted very often. Furthermore, the woods for sanshin are gradually nearing depletion and the demand of alternate woods has increased. The scientific evaluation of the acoustical performance of the woods would enable the appropriate material selection of the woods for sanshin, and would also be useful for the selection of alternate woods. In this research, Ryukyu kokutan (Diosphyrosferrea), isunoki (Distylium racemosum), and mokumaou (Casuarina equisetifolia, as a candidate for alternate woods) were selected. Samples were tested by conducting the free deflection vibration method at both ends. After the tests, sao were manufactured by the craftsman using these woods and the acoustical characteristics were evaluated as an actual sanshin. As a result, the trend of the attenuation depending on the types of the woods was consistent with the vibration tests of the raw wood and the acoustical evaluation by sanshin. This result suggests that the performance as the sao of sanshin could be evaluated in a state of raw wood. Also, the feasibility of mokumaou as an alternate wood of sao was confirmed.

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