• Journal of the Korean Wood Science and Technology
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• v.21 no.4
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• pp.73-78
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• 1993

Crystal structure of tension, opposite and lateral wood of Platanus orientalis L. were analysed in some aspects of crystallinity index, crystallite size, d-spacing of (200) and (004), and integrated intensity ratios with X-ray diffraction method. Crystallinity index and crystallite width in tension wood appeared somewhat larger than opposite or lateral wood. However, d-spacing and integrated intensity ratios were nearly identical irrespective of tension, opposite, and lateral wood.

• Journal of Applied Biological Chemistry
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• v.51 no.3
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• pp.83-87
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• 2008

Tension wood, a specialized tissue developed in the upper side of the leaning stem and drooping branches of angiosperm, is an attractive experimental system attractive for exploring the development and the biochemical pathways of the secondary cell wall formation, as well as the control mechanism of the carbon flux into lignin, cellulose, and hemicellulose. However, the mechanism underlying the induction and the development of the tension wood is largely unknown. Recently, several researchers suggested the possible roles of the plant growth hormones including auxin, gibberellin, and ethylene mainly based on the expression pattern of the genes in this specialized tissue. In addition, expressed sequence tag of Poplar and Eucalyptus provide global view of the genetic control underlying the tension wood formation. However, the roles of the majority of the identified genes have not yet been clearly elucidated. The present review summarized current knowledge on the biosynthesis of tension wood to provide a brief synopsis of the molecular mechanism underlying the development of the tension wood.

• Journal of the Korean Wood Science and Technology
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• v.25 no.3
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• pp.43-49
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• 1997

The lengths of fibers and vessel elements, vessel diameters, and ray spacings of tension and opposite woods in Quercus mongolica Fischer and their radial variations were examined. Crystallinity indices and crystallites orientations of tension, opposite and lateral woods were also investigated. The lengths of fibers and vessel elements, and ray spacings of tension wood were longer and denser than those of opposite wood, respectively. In the latewood, the vessels of tension wood had a little larger diameters than those of opposite wood. whereas the vessel diameters of earlywood were similar in both woods. With the exception of vessel diameters of earlywood, there were differences between tension and opposite woods in all anatomical characteristics examined. In the radial variation pattern, the fiber lengths of both woods increased markedly to about 15th annual ring and thereafter remained virtually constant. The vessel element lengths of earlywood in tension wood increased to certain annual ring and thereafter were stabilized, but opposite wood had a relatively constant trend from pith to bark. Those of late wood in both woods increased to certain annual ring and thereafter showed constant patterns. Vessel diameters appeared to show similar trend in both woods. Ray spacings decreased to about 15 annual ring and thereafter were stabilized in both woods. In the fine structures, tension wood had higher crystallinity index and better crystallites orientation than opposite and lateral woods.

• 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.

• Journal of the Korean Wood Science and Technology
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• v.17 no.2
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• pp.1-12
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• 1989

To study the structure of opposite wood in the angiosperms. samples were cut from stems and branchs of 10 spcies growing in Korea. The opposite side was defined as being along a line passing from the most wide annual ring of the tension wood on the upper side to the pith and extrapolated through the opposite side. lateral sides being on the right and left of this line. The stem woods growing almost horizontally were surveyed the structural features of the well-developed opposite wood for the tension wood. In the annual-ring of the well-developed opposite woods. an investigation was made on how the dimension of elements, microfibril angles. and cell wall layers change from tension side to opposite side. The structural characteristics of opposite wood in hardwoods realized in this study are as follows: 1. The vessel diameters increased continuously to ward the opposite side in which the values were maximum. The vessel length also increased toward opposite side. but the rates of increase were smaller than those in the vessel diameters. 2. The wood fiber length were decreased from tension toward opposite side. but the rates of decrement were f1actuated within the sampled species. 3. The microfibril angles had the minimum values on the tension side. then increased steeply toward the opposite side in which the values maximum. 4. In the percentage of elements the vessel elements increased continously at a relative rate from the tension to opposite side, whereas the values of the wood fibers were lower in the opposite than the tension side, but the' variation patterns of rays were not seem distinctly. 5. The component layers of the wood fiber in the opposite woods were very similar to the lateral woods.

• Journal of the Korean Wood Science and Technology
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• v.31 no.6
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• pp.1-7
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• 2003

The phase transformation from cellulose I into cellulose II in woods by way of Na-cellulose I was examined by x-ray diffraction analysis.The formation of Na-cellulose I in woods increased with the increase of treating time in alkali solution. When compression wood was treated with 20% NaOH solution at room temperature for 1 day, the x-ray diagram showed only Na-cellulose I. On the other hand, the x-ray diagram of tension wood showed a mixture of cellulose I and Na-cellulose I. Cellulose I of tension wood could not be transformed completely into Na-cellulose I even after 10-day treatment, but was transformed into Na-cellulose I after 30-day treatment. Na-cellulose I of compression and tension woods was converted to the cellulose I pattern and the mixture of cellulose I and cellulose II, respectively, after washing with water and drying at 20℃. Cellulose I regenerated from Na-cellulose I in wood could not be converted to cellulose II by delignification. Thus, it revealed that the delignification of the alkali-treated wood did not affect their cellulose structures. From the results, therefore, it can be concluded that lignin in woods prevents the formation of the stable Na-cellulose I and the conversion from cellulose I to cellulose II. This means that the conversion of chain polarity of wood cellulose hardly occurs during mercerization because cellulose microfibrils are fixed by lignin which not to be intermingled.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.20-27
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• 1989

This experiment was made to find the peripheral variations of annualring widths, the cell dimensions, microfibril angles and bulk densities within each annual-ring of horizontal-growing young tree of beech(Betul a platyphylla var. japonica) and Oak (Quercus variabilis) from the tension to the opposite side. Also a comparision between the features of the obnormal annual ring for horizontal-growing year and normal annual ring for the straight-growing years was made. The dimension of propotion of the element, the microfibril angles and the bulk density decreased or increased continuously toward opposite side which showed minimum or maximum value. The dimension of elements the microfibril angles and the bulk density decreased or increased continuously towards opposite side which showed minimum or maximum value. The dimension of elements. the microfibril angles and the bulk density in the normal annual rings were similar to those in the lateral woods. whereas were significantly more different in the tension wood than in the opposite wood. The features of typical opposite wood in the hardwoods were influenced by the locations within the inclined stems than effects of the decrease in the annual ring width. The oppostie woods in hardwoods did not conform to the tension wood and lateral wood. The abnormal annual ring included the opposite wood, lateral wood similar to normal wood and tension wood having specialized structure even in the same annual ring.

• Journal of the Korean Wood Science and Technology
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• v.42 no.5
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• pp.510-515
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• 2014

The anatomical and physical properties of tension wood (TW), opposite wood (OW) and lateral wood (LW) in the branches of Korean paulownia (Paulownia coreana) were compared. The diameter of TW vessels was larger than that of OW and LW vessels. The most distinctive feature of TW fibers was the presence of a gelatinous layer (G-fiber). The cell wall of TW fibers was nearly three times as thick as that of OW and LW. TW differed from OW and LW in density, X-ray diffraction pattern and shear and compressive strengths. The results obtained in this study showed clear differences in the anatomical and physical properties of TW, OW and LW of Paulownia coreana branch woods.

• Journal of the Korea Furniture Society
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• v.11 no.2
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• pp.7-12
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• 2000

This paper describes the bending strength properties of laminated woods which had three kinds of specimens according to finger length-12, 4.5 mm and butt joint and the acoustic emissions (AEs) generated during the test. 3-ply laminated wood beams were tension side layers (lower layers) composed of one middle lamina and two side-jointed laminae, with one butt joint ($_1BJ$), one finger joint (12mm, $_1FJ_{12}$) or one finger joint (4.5mm, $_1FJ_{4.5}$) in the middle lamina of tension side layer. And 3-ply laminated wood beams were tension side layers (lower layers) also composed of one lamina, with one butt joint (BJ), one finger joint (12mm, $FJ_{12}$) or one finger joint (4.5mm, $FJ_{4.5}$/) in tension side layer. Cryptomelia pieces were cut for butt and two finger types and glued with resorcinol-phenol resin adhesive. The results were as follows It was not effective in the bending modulus of elasicity (MOE) with IFJL type and had no difference from finger length. The bending modulus of rupture (MOR) of laminated wood beams including finger joint was the same values as that including butt feint and had no difference from finger length. It was effective in MOE with FJL type and had no difference from finger length. The effect of finger joint on MOR was much higher than that of butt joint but had no difference from finger length. The AE generation time of IFJL type was earlier than that of the control wood and the number of AE count was much more than that of the control wood. However, the AE generation time of FJL type was earlier than that of the control wood and the number of U count was much fewer than that of the control wood.

• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.6-12
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• 1998

Test results of domestic softwood lumber were presented to examine the notch effect of beams and compare to present AIJ(Architecture Institute of Japan) formula in notched wood member especially positioned in bottom side (tension side) of a beam. Notched lumber was tested under following condition : each specimen supported simply, and subjected to third-point loading at points of 1/3 of the span length. Notch was located opposite side to loading direction and notch depth were 1/6, 1/4, 1/3 of beam depth. Deflection and load were measured by digital dial guage each in 25kgf increment. Bending test results were as follows; Mpro/Mmax range (proportional and maxium bending moment ratio in notched beam) was 0.5 - 0.65. It was considered that maxium bending moment was about 1.5 times to proportional bending moment in notched beam and showed same tendency in the test result of ordinary wood specimens. AU standard formula for the tension side notch, Mmat = 0.6 ${\times}$ (Zo $\sigma$), the constant 0.6 was suitble for notch ratio(notch depth to beam depth) 1/6, but this ratio for 1/4, and 1/3 was not. So it is preferable to accept smaller value than 0.6 for notch ratio more than 1/3. These experiment results showed critical effect in tension side notched wood beam especially in greater than notch ratio 1.3 of wood beam. From the above results, it is recommened to revise design formula adoptable to domestic wood constructon member with tension side notched member.