The major change in wood adhesion during the past decade was developing the adhesives for countermeasure against emission of formaldehyde and VOC. The emission of formaldehyde from wood-based materials has cleared the reference level of Ministry of Land, Infrastructure, Transport and Tourism by using above adhesives. It is considered that future adhesives will be more environment-conscious, such as sick-house countermeasure adhesives, adhesives from nonfossil resources, and dismantlable adhesives, which were described and commented on from the authors' standpoint. Here some of the current and author's concept are described. The concept of gecko's foot is good for developing new adhesives, and has great potential to lead us to new future adhesives.

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The material properties of compressed wood were investigated according to the compression ratio, considering its use as mechanical fasteners. Compressed wood made of Japanese cedar in various compression ratios was provided for material tests such as tension, compression, bending, shearing and bearing. The relationship between stiffness or strength and density were investigated. In order to clarify the influence of the improvement of material properties, test results were standardized by using density and material properties of non-compressed wood. As a result, it was made clear that tension and compression properties parallel to the grain and bending properties improved in proportion to the increment of density regardless of the deformation of the cell wall. Shear elastic modulus and strength on the LT plane increased almost in proportion to the density, but no such improvement was observed in those on the LR plane. Shear elastic modulus on the LT plane and strength on the LR plane showed rather higher values than the ideal relationship with density, and elastic modulus on the LR plane and strength on the LT plane showed rather lower values at low density and then became higher than the ideal relationship. Those tendencies were qualitatively explained by a model of cell wall deformation. MOE and strength on bearing in the T direction increased following a power function with index of 2 and 1.8, respectively. On the other hand, their changes in the R direction were relatively small until the cells of early wood fully turned into compressed cells, and then they increased very drastically. This tendency was very similar to the stress-strain relationship in R-compression of normal softwood, and was explained well by the honeycomb cell model of the deformed compressed cell.

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The relationship between internal checks in high temperature dried timber and vibrational properties was investigated. Vibration tests were carried out on 45 high temperature dried sugi boxed heart square sawn timbers (11.4×11.4×304 cm) and 20 timbers dried at intermediate temperature. Longitudinal Young's modulus E_l, flexural Young's modulus E_g, torsional shear modulus G_t, and flexural shear modulus G_g were obtatined by vibration tests. After the vibration tests, internal check length in 5 cross sections of timber was measured. Flexural shear modulus showed lower values in the presence of internal checks, and its ratio to flexural Young's modulus, G_g/E_g, became smaller. Internal checks could be evaluated by measuring the dynamic shear modulus.

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In the present study the sound insulation of three-layered walls composed of cedar timber and plywood was measured and evaluated in accordance with JIS A 1416 and JIS A 1419-1, and compared with that of conventionally constructed walls. The results were as follows : (1) The three-layered walls have higher sound insulation over all frequency ranges than conventionally constructed walls ; (2) They have no clear coincidence effect in the range from 2000 to 4000 Hz ; (3) The center board is efficient in that there was no sound insulation reduction by the outlet holes which are usually found in two-layered walls ; (4) Though three-layered walls which bond plasterboards to both sides of reinforced concrete walls have sound insulation reduction in the frequency range from 200 to 400 Hz by lower frequency resonance, the developed three-layered walls have little insulation reduction by that resonance.

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In the present study the floor impact sound insulations of three-layered floors composed of cedar timber and plywood was measured and evaluated in accordance with JIS A 1418-1, JIS A 1418-2, and JIS A 1419-2, and compared with that of conventionally constructed floors. The results were summarized as follows : (1) The light and heavy floor impact sound insulations of the three-layered floors was better than that of conventionally constructed floor ; (2) The light floor impact sound insulation of the three-layered floors with rubber supporting the upper air layer was much better than of the others ; (3) When the joist interval is changed from 433.5 mm to 289 mm, the heavy floor impact sound insulation was improved by the increase of the stiffness ; (4) When the CFRP plate was bonded to the floor with the joist interval of 433.5 mm, the heavy floor impact sound insulation was improved. However, the CFRP plate had no effect in the case of the floor with the joist interval of 289 mm, because bonding the CFRP plate to the wooden floor was not enough to increase the stiffness.

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The ratio of working stress to allowable stress of beams in three wooden houses, which were build in a heavy snow area, was investigated. Their load-bearing ratio of the maximum flexure to the flexure limit was also surveyed. Then the condition of the stress or the maximum flexure at each duration of load at the maximum load-bearing ratio was examined. The results of investigation suggest that sufficient safety margins were possessed because the load-bearing ratio was less than 20% on average in more than 70% of all beams. However some exceptions exceeding more than 80% of the maximum load-bearing ratio were also existed. Concerning short-span 2nd floor beams, the design placing a shear wall at the middle span was the main reason for possessing less safety margin. For 2nd floor beams which spans of more than 4P (P=910 mm) and roof beams which span is more than 3P, the flexure limit was the dominant factor to determine the maximum load-bearing ratio.

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Breeding and screening of strains suitable for sugi wood culture were performed to establish the cultivation technique for sawdust-based cultivation using sugi wood for Lentinula edodes. As a result, HS807 was selected as a strain suitable for sugi (Cryptomeria japonica) wood sawdust-based cultivation. HS807 gave about 6 times higher yield than that Hokken No. 600 which is suitable for hardwood sawdust-based cultivation. However, the yield was about one half compared with that of hardwood sawdust-based cultivation. Physical and chemical analyses of mycelial blocks were performed to evaluate incubation properties of the HS807 strain suitable for sugi wood. As a result, mycelium in sugi wood medium is found to be of lower quantity as compared to konara wood medium. Therefore, it was suggested that the increase in the quantity of mycelium during incubation is an important factor for evaluation of fruit body flushing.

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