• Journal of the Korean Wood Science and Technology
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• v.26 no.2
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• pp.1-5
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• 1998

Nail withdrawal tests were conducted on clear wood of radiata pine. Nails were driven into the earlywood and latewood zones of each specimen, and nail withdrawal tests were then performed. Nail withdrawal loads were strongly dependent on earlywood and latewood and on nail position. The average load values for nail withdrawal in both the tangential and longitudinal directions were higher for latewood than for earlywood. Linear and nonlinear regression analyses of nail withdrawal load with specific gravity showed no discernible differences. Good correlations were obtained between nail withdrawal load and specific gravity.

• Journal of the Korean Wood Science and Technology
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• v.29 no.2
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• pp.76-83
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• 2001

This study was carried out to clarify the mechanical behaviour of the earlywood and the latewood to the compressive load applied parallel to the grain. The results from the analysis of Japanese cedar wood (Cryptomeria japonica) were used to introduce a concept on stress-strain behaviour of the earlywood and the latewood. There was a significant differences in the mechanical behaviour of the earlyWood and the latewood. In the earlywood, the rate of cell wall upon annual ring was almost similar and the strain increased linearly with the stress increased. However, the rate of cell wall upon annual ring varied in the latewood and the strain of that increased curve-linearly with the stress increased. The longitudinal compression modulus of elasticity (MOE) variation by loading speed on latewood specimens and earlywood specimens shows no significant difference. The modulus of rupture (MOR) and MOE of latewood were about 4 times higher than those of earlywood.

• Journal of the Korea Furniture Society
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• v.17 no.4
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• pp.49-57
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• 2006

Larix kaemferi is now a major economic kind of trees and is produced in large quantity every year. Thus, the study of Larix kaemferiis conducted to acquire the basic date of measures for the reasonable use, clarifying the relation with the compression strength parallel to grain according to anatomical properties by heartwood and sapwood, and earlywood and latewood. As the length of an earlywood tracheid and the radial wall thickness of earlywood and latewood tracheids increased, the compression strength rose, and as the height of uniseriate ray in cell number increased, the compression strength parallel to grain fell. The major anatomical factors effecting on the compression strength parallel to grain of heart wood were the radial wall thickness of a latewood tracheid and the length of a latewood tracheid, while in sapwood, the length of an earlywood tracheid and the radial wall thickness of earlywood and latewood tracheids were the major factor on it.

• Journal of the Korea Furniture Society
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• v.19 no.2
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• pp.111-115
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• 2008

An experiment was conducted to know ultra-pure distilled water penetration depth through large vessel, small vessel, latewood fiber and earlywood fiber in longitudinal direction of Castanea crenata. In heartwood, latewood fiber transported water more than large and small vessel. While in sapwood, small vessel conduction depth was found the highest. Penetration depth of water after 15.0 seconds, no significant difference was observed among earlywood fiber, latewood fiber and earlywood vessel. Whilst in heartwood, no statistical difference was observed among earlywood fiber, latewood fiber and earlywood vessel. At the beginning, the speed of water penetration was high and then gradually decreased.

• Journal of the Korean Wood Science and Technology
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• v.20 no.2
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• pp.51-60
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• 1992

This study was performed to investigate the effect of green sorting before drying on the high-temperature drying characteristics of southern yellow pine dimension lumber(2"${\times}$6"${\times}$12'). To test the advantages of weight sorting, green lumber was seperated into heavy(above 55 1b), medium(50-55 1b), and light(below 50 1b)weight classes. Pieces in each weight class were subgrouped into high(above 35%) and low(below 30%) latewood groups. Groups were dried and seperated by a standard commercial high-temperature schedule; dry bulb temperature $245^{\circ}$ F, wet bulb temperature $180^{\circ}$ F, and air velocity 1200fpm. The results obtained were as follows; 1. There was a highly significant correlation between annual rings per inch(X) and percent-latewood(Y). The regression equation was Y=24, 5047+1.3272X. 2. There were highly significant correlations between either annual rings per inch($X_1$) or percent-latewood($X_2$) a.d specific gravity in green wood(Y). Their regression equations were Y=0.4260+0.0081$X_1$ and Y=0.3749+0.0029$X_2$, respectively. 3. Heavier weight charges dried more slowly than lighter weight charges. 4. Board-to-board variation in green or dry moisture content was less for all seperate weight classes than for unseperated control charges. 5. Lower latewood pieces had higher initial moisture content than higher latewood pieces, and then drying time for lower late wood pieces was longer than higher latewood pieces.

• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.61-70
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• 2003

The size distribution of the free water paths between earlywood and latewood for six species in the heartwood of softwoods was estimated from the amount of dehydrated free water under various centrifugal fields, such as 2,200, 3,300, 4,800 and 6,900 rpm. The centrifugal method is based on the concept that water movement occurs by the balance of centrifugal force and water potential by meniscus. Water stops where the pressure differential is zero. In the centrifugal field, only two factors affect water movement in wood, that is, centrifugal force and water potential. Also, the water permeability was evaluated from the relationship between the water saturation ratio after the centrifugal treatment and the measure of water potential in specimen. The results showed that Cryptpmeria japonica had clear peaks at 0.70 ㎛ in earlywood and at 0.50 ㎛ in latewood. Tsuga sieboldii and Larix kaemferi had peaks at 0.50 and 0.30 ㎛ in both earlywood and latewood, respectively. Abies firma showed peaks at 0.70 ㎛ in earlywood and at 0.30 ㎛ in latewood. The water permeability of earlywood was higer than that of latewood for all softwoods except Pseudotsuga menziesii.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.1-7
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• 2005

This study was carried out to investigate on the formation of resin canal, tylosis and latewood of the major species growing in Chuncheon. Two species of softwoods (Pinus densiflora and Pinus koraiensis) and two species of hardwoods (Quercus mongolica and Robinia pseudoacacia) were used in this experiment. The resin canals of P. densiflora and P. koraiensis were formed from the beginning through the middle of July and in the beginning of May, respectively. It is clear that the resin canal of P. koraiensis was formed much earlier than that of P. densiflora. The tylosis in vessel of Q. mongolica was formed in the middle of May, and the formation in R. pseudoacacia was in the end of May. The latewood in P. densiflora was formed in the middle of August. The latewood in P. koraiensis was formed from the end of September through the beginning of October. While latewood vessels in Q. mongolica were formed in the end of May, and those in R. pseudoacacia from the beginning of June through the middle of June. Consequently, the period of resin canals, tyloses and latewood formation was different among the sample trees, even though the trees were grown under the same conditions.

• Journal of the Korean Wood Science and Technology
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• v.21 no.2
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• pp.73-80
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• 1993

Pinus koraiensis is one of the most important reforestation species which had widely been planted around the country. Therefore, there are great research needs on the fundamental properties of wood to extend the frequency of uses and adequate availabilities. Research results on the characteristics of anatomical wood properties and changes are summarized as follows: 1. At a horizontal direction of tree trunk, the tracheid length at outer wood gradually becomes shorter as it reaches to pith. The tracheid length having between 32 and 42 annual rings showed over 2.5 times longer than that of pith, and also its length increases from the bottom to the top of the stem. 2. The tracheid diameters in latewood showed a little fluctuations, and the shortest near to the pith in earlywood. The tracheid diameters in earlywood are more than 2 times those of latewood, and the differences between the mature and juvenile wood in earlywood are less than 10${\mu}m$. 3. The tracheid wall thickness in early wood showed a little fluctuations. On the contrary, tracheid wall thickness in latewood rapidly increases from the pith to the bark. The tracheid wall of mature wood showed 10 to 20% thicker than that of juvenile wood. 4. The fibril angle at the secondary walls of tracheid within an annual ring showed higher degree in earlywood than that of latewood. The highest tracheid fibril angle was observed at around the pith of both earlywood and latewood. Then, fibril angle slowly decreased toward outer wood, and was stabilized after 15 years. 5. Structural boundaries between mature and juvenile wood from Pinus koraiensis are divided by 13 to 19 annual ring and distance of 5 to 8cm from the pith.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.34-36
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• 2003

In boreal conifers in China's Northeast area, maximum latewood density (MXD) of tree-ring varies in response to growing season temperature. Forest net productivity can be estimated using the Normalized-difference Vegetation Index (NDVI) calculated from satellite sensor data. MXD from the Mohe site in this area was compared with estimates of NPP for 1982-1999 produced by the NDVI model, which was established based on the relationship of leaf area index (LAI) and NDVI. The result shows that the MXD series correlated significantly with the NDVI model estimates series, suggesting that MXD appeared to be an appropriate index for productivity or canopy growth in region where forest productivity is strongly temperature-related.

• Journal of the Korean Wood Science and Technology
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• v.24 no.3
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• pp.12-17
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• 1996

This study was carried out to investigate some mechanical properties for wood rational utilization of heartwood and sapwood in radiata pine according to basic density, ring width and proportion of latewood which were grown in New Zealand. This result were summarized as follow: Heartwood showed 35.78(MPa) of the compression strength parallel to the grain while sapwood showed 42.08(MPa). The modulus of rupture in static bending was higher in sapwood showing 86.12(MPa) than in heartwood 72.99(MPa) Heartwood had 7.38(GPa) for the modulus of elasticity in static bending and sapwood 8.17(GPa). As the basic density and proportion of latewood increased: compression strength parallel to the grain, MOR and MOE in static bending had a tendency to increase. As ring width increased, the mechanical properties decreased.