Mokuzai Gakkaishi
Online ISSN : 1880-7577
Print ISSN : 0021-4795
ISSN-L : 0021-4795
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Volume 60, Issue 1
Displaying 1-8 of 8 articles from this issue
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CategoryI
  • Dendrochronological Study on Tree Growth Responses to Climate in Okutama, Tokyo II.
    Relationships between climate and tree-ring information for seven tree species
    Takao Momoi, Hiroya Ohbayashi, Toshiro Tochigi, Jun Kobayashi, ...
    2014 Volume 60 Issue 1 Pages 1-8
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.1
    JOURNAL FREE ACCESS
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    The relationships between various climate parameters and previously constructed tree-ring indices (annual ring width index, IWar; annual ring density index, IDar) for seven tree species found in Okutama, Tokyo were examined. Significant correlations between tree-ring indices and climate parameters were observed. The four major correlations were: 1) a positive correlation between IWar and monthly mean temperature from January to March of the current year; 2) a positive correlation between IDar and monthly mean temperature from May to August of the current year; 3) a negative correlation between IDar and monthly mean temperature from May to July of the previous year; and 4) a negative correlation between IDar and number of days with precipitation from June to September of the current year. These four relationships also demonstrated the varying responses of different tree species to variations in climate. The significant correlation coefficients obtained from the relationships between the tree-ring indices and a) monthly maximum temperature were greater than those obtained from the relationships between the tree-ring indices and b) monthly mean temperature and c) monthly minimum temperature.
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  • A Simple Method for Estimating the Radioactive Contamination Level of a Standing Tree by Measuring its Surface Contamination Density
    Youki Suzuki, Katsushi Kuroda, Tsutomu Takano, Chunhua Zhang, Toshikaz ...
    2014 Volume 60 Issue 1 Pages 9-15
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.9
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    This paper outlines the development of a simple method for estimating the radioactive contamination level of individual trees, for the purpose of contributing to forest management. This has become a difficult problem owing to the Fukushima Dai-ichi nuclear accident triggered by the earthquake of March 11, 2011 in Japan. To develop a simple estimating method, the relationship between the surface contamination density and the radiocesium concentration of the trees collected at Fukushima forests was investigated. The surface contamination densities were measured using a commercial GM-tube survey meter combined with a shielding box, which was filled with water to improve the detection limit by reducing background influence. The surveyed trees were felled and divided into bark, sapwood, and heartwood, and then the radiocesium concentrations were measured by gamma-ray spectrometry after grinding and oven-drying. The relation between surface contamination density and radiocesium concentration could be expressed by the function, y = AxB, in all of the trees surveyed. This finding suggests that it might be possible to estimate the degree of radioactive contamination of a standing tree by only measuring its surface contamination density using a simple GM-tube survey meter, and consequently, it will be helpful for future forest management.
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CategoryII
  • Compressive Strength Properties Perpendicular to the Grain of Cross-Laminated Timber (CLT) Composed of Sugi Laminations
    Hirofumi Ido, Hirofumi Nagao, Sachiko Miura, Atsushi Miyatake
    2014 Volume 60 Issue 1 Pages 16-22
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.16
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    Compressive tests perpendicular to the grain of Cross-Laminated Timber (CLT) were conducted while changing the number of layers, lamina grade composition, loading plate direction against the outer lamina direction, and the loading direction to the specimen. This was done to clarify the compressive strength properties perpendicular to the grain under each conditions, and a simplified manner of evaluating the compressive strength properties perpendicular to the grain was proposed. Following compressive tests perpendicular to the grain, it was found that the factors dictating the compressive strength properties perpendicular to the grain were loading plate direction against outer lamina direction and loading direction, while the number of layers and lamina grade composition had less impact. The stress at the CLT proportional limit was estimated using the stress at the proportional limit of lamina, and the estimated and measured values corresponded.
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  • Effects of Laser Incising on Lumber Strength II.
    Bending strength of square lumber
    Keisuke Ando, Nobuaki Hattori
    2014 Volume 60 Issue 1 Pages 23-27
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.23
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    To evaluate the strength of laser incised lumber, sugi (Cryptomeria japonica D. Don) square lumber was used for bending strength tests. Specimens were incised by CO2 laser through the thickness with three kinds of incising densities ranging from 0 to 40000 holes per square meter. Bending strength tests with loading direction parallel to the incised holes were performed with all incising densities. Furthermore, specimens with 10000 holes per square meter were tested with the loading direction perpendicular to the incised holes. Results showed that bending strength of incised lumber declined significantly for incising densities of more than 10000 holes per square meter. The effect of loading direction on bending strength of square lumber incised with 10000 holes per square meter was not significant.
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  • Results of 10 Year Outdoor Exposure Tests for Sugi Glulam II.
    Distribution form and rate of decline of shear strength
    Yasuo Yanagawa, Kaori Mitsuna, Hiroshi Wada
    2014 Volume 60 Issue 1 Pages 28-34
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.28
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    We manufactured glulams with wood preservative (ACQ, AZP) treated and untreated laminae using two adhesive resins (PRF and API), and conducted aging treatments as follows.: (1) 10 years outdoor exposure of glulams, (2) 2 years outdoor exposure of block-shear-form pieces of 10mm and 25 mm width sawn from glulams, and (3) 1∼20 cycles of vacuum-pressure treatment of 25mm wide block-shear-form pieces. We conducted block-shear-tests after aging treatments, and goodness-of-fit tests of shear strength to distribution forms were performed. As a result for (3), no tendencies were recognized as to fits of distribution forms, and for (1) and (2), it was suggested that some specimens tend to fit the 2P or 3P Weibull distribution. We investigated the rate of decline of shear strength from the slope of the liner regression line obtained from a plot of square root of exposure month or cycles as x axis and ratio to initial average shear strength as y axis. For ACQ treated specimens, a difference of rate of decline was observed among (1)∼(3). For AZP treated and untreated specimens in (2), only slight differences between slope values were found due to width of specimen, and in (3), slope values obtained from the west side of glulams without exterior finish were nearly 0.
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CategoryIII
  • Nondestructive Evaluation of the Heartwood Color of Standing Sugi Trees by Using the Lateral Impact Vibration Method
    Hiroshi Suyama
    2014 Volume 60 Issue 1 Pages 35-40
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.35
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    The heartwood color of standing sugi (Cryptomeria japonica) trees was evaluated using the lateral impact vibration method. Evaluations were obtained using the diagnostic index (DFr), which is the product of the diameter D of a stem and the resonance frequency Fr obtained when the stem is laterally impacted. The heartwood color was evaluated on the basis of the following assumptions. A lower DFr implies a higher moisture content (Mc) in the heartwood, and a higher Mc implies lower brightness (L*) of the heartwood color. Therefore, a low DFr might imply a low L*. Seven hundred trees were measured using this method. Seventy of the 700 trees were cut to check the color of the heartwood. The increase or decrease rate R in the DFr of each tree against the regression line of D and DFr for all the cut trees was calculated as the index for evaluating L*. The calculations revealed a negative correlation between R and Mc (r = 0.71) and between Mc and L* (r = 0.70). Further, a positive correlation (r = 0.53) was observed between R and L*. The correlation coefficient between R and Mc was not high, but the brightness of the heartwood color (L*) of the standing sugi trees could be classified into three groups by using the index R. The use of heartwood color evaluation by this method in thinning is also discussed.
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  • Effects of Sawn Splits on Buckling, Bending, and Shearing Properties in Full-Size Squared Lumber of Hinoki (Chamaecyparis obtusa)
    Yuusaku Kameyama, Yasuhiro Andou, Hidekatsu Ohno, Yuusuke Anzai, Futos ...
    2014 Volume 60 Issue 1 Pages 41-47
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.41
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    Effects of depth (30 and 50% of lumber width) and inclination to the loaded face of sawn splits on buckling, bending, and shearing properties were investigated for full-size squared lumber (10.5 by 10.5 cm in cross section) of hinoki (Chamaecyparis obtusa Sieb. et Zucc.). No significant differences in buckling properties, and modulus of elasticity and proportional limit ratio in static bending were found between lumber without or with a sawn split. On the other hand, when load was applied to the side opposite to the sawn split, modulus of rupture in static bending was significantly decreased for all depths of sawn split. In addition, shearing strength determined by an asymmetric four-point loading method largely decreased when the load was applied to the side perpendicular to the sawn split. However, modulus of rupture in static bending and shearing strength of lumber with a sawn split with depth 50% of width exceeded the design strength requirement values of ungraded hinoki lumber listed in Bulletin No.1452 of the Ministry of Construction, Japan. The obtained values of buckling strength in all specimens tested here were higher than the buckling strength of ungraded hinoki lumber estimated by compression design strength based on “Standard for Structural Design of Timber Structures” of the Architectural Institute of Japan.
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  • Dyeing Properties for Fabrics of the Wood of Toxicodendron vernicifluum
    Koh Hashida, Masanobu Tabata, Yoshitaka Kubojima, Rei Makino, Satoshi ...
    2014 Volume 60 Issue 1 Pages 48-54
    Published: January 25, 2014
    Released on J-STAGE: January 28, 2014
    DOIhttps://doi.org/10.2488/jwrs.60.48
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    To utilize unused wood of Toxicodendron vernicifluum as a natural dye, dyeing properties for fabrics of the wood were investigated. To obtain the phenolic pigments, the wood was extracted with hot water under various conditions. It was revealed that a higher amount of phenolics was extracted by the addition of sodium carbonate. The extract solution was found to have a good dyeing affinity for nylon, wool and silk fabrics. Using the solution from the extraction with hot water containing sodium carbonate, deep dyeing could be attained by adding acetic acid. In addition, by mordanting with metal salt, deep dyed fabrics were colored more deeply than the fabrics dyed with the hot water extract. The washing fastness of the dyed cotton fabric was poor, but it was improved by mordanting with metal salt, especially with iron (II) acetate. Moreover, it was found that the dyed cotton fabrics exhibited definite antibacterial activity against Staphylococcus aureus and Escherichia coli.
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