• Journal of the Korea Furniture Society
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• v.10 no.1
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• pp.23-32
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• 1999

The ultrastructural characteristics of shear fracture surfaces of laminated wood prepared from major four Korea wood specimens were examined. Commercial urea and urethan resin were used as adhesives for laminated woods of both homospecies and heterospecies. The morphology of fracture surface was observed using an optical microscopy and scanning electron microscopy. Three anatomical failure types were recognized : intercell failure, intrawall failure and transwall failure. In dry specimen, failure occurred mainly in woods. Laminated woods of softwoods showed mostly intrawall failure and transwall failure of tracheids, and them of hardwoods indicated mainly intrawall failure and interwall failure. Laminated woods prepared with urethan resin showed coarse fracture surface, on the other hand, those prepared with an urea formaldehyde resin had clean surface. In wet specimen, failure occurred dominantly in glue line. Intrawall failure and flags were characterized in laminated wood prepared with urethan resin. In heterospecies laminated woods, failure was occurred mainly in softwood. Consequently, fracture morphology of laminated wood may be influenced by adhesives, moisture content, species and anatomical characteristics.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.351-358
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• 2011

This study has been carried out to understand the fracture characteristics of the tension wood of Quercus mongolica under the shear and bending stress. Macroscopically, the wood fluff in the shear surface appeared more frequently in tension wood than sound wood, and more coarse wood fluffs were observed in 30% than 10% moistured shear surface. In the fractured tension wood from bending stress, more thick and long wood fiber appeared than sound wood. The observation using scanning electron microscope indicated that both sound and tension wood samples from radial shear surface showed the intrawall dominated failure and the fracture surface of the ray parenchyma cell showed the transwall dominated failure. In tangential shear surface, wood fiber surface showed the intrawall failure and short and coarse wood fiber was observed in tension wood. Ray parenchyma cell of sound and tension wood samples showed the transwall failure. The surfaces of tension wood’s ray parenchyma cell were relatively clean. The fractured tension wood from bending stress showed unsharp and flat wood fiber compared with sound wood.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1A
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• pp.58-66
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• 2011

In this paper, we propose a self-organized frequency allocation scheme for femto-cell deployment to avoid intercell interference, thereby reducing cell-registration failure. The proposed scheme follows two steps which if necessary manipulate frequency-band reallocation of existing femto-cells to accomodate newly incoming femto-cells. In the first step named "initial frequency allocation", each femto-cell collects neighboring femto-cells' frequency usage state by listening the broadcasting channels, and then selects one of interference-free frequency-bands. If no inference-free band is available, the second step named "frequency adjustment" starts, where frequency-band reallocation is properly performed from the aspect of overall performance improvement. Numerical results shows that the proposed scheme outperforms the best SINR scheme, which has been practically applied to femto-cell deployment, in terms of cell-registration failure probability and system overhead.