• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.96-103
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• 2003

This study was conducted to evaluate the tensile properties of metal plate connector for the domestic major softwoods, such as Korean red pine, Korean white pine, and Japanese larch. The maximum tensile load of Korean red pine was 3,612kgf in AA type, it was 1.2 and 1.7 times higher load than that of Japanese larch and Korean white pine. In EA type, it was 2,704kgf, and 1.1 and 1.5 times higher than the loads of Japanese larch and Korean white pine. The failure modes of metal plate connector were metal plate withdrawal, plate tensile failure, and wood shear block failure. The failure mode of Korean red pine connector was tensile failure of plate, that is reason of the high tensile load resistance for metal plate connections in Korean red pine. The mechanical properties of metal plate connector could be predicted by the Foschi model parameter. In the initial stage, the Korean red pine connector was stiffer than the other species. The design values for metal plate connector per tooth was 25, 22, and 15kgf for Korean red pine, Japanese larch, and Korean white pine in AA type and 19, 17, and 13kgf in EA type.

• 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.

• Korean Journal of Environment and Ecology
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• v.16 no.2
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• pp.141-148
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• 2002

This study was carried out to estimate the effect of forest fire on herb layer development and chemical properties of soil. The forest fire was in April 2000 in Pinus rigida(softwood) and Robinia pseudoacacia(hardwood) dominant forests at Gaejoksan, Daejeon. Vegetation studies were in the two communities and herb layer development study was in July using dominance of Dierssen. The coverage of herb layer was higher in the burned area than in the unburned area in the two study communities. There was no different herb layer species number between the burned and unburned areas, but there was different herb layer species number between the two communities. Soil samples were collected at 0～10cm and 10～20cm soil depths from the unburned and burned sites after 3 days and 8 months of forest fire. There was no forest floor in burned site, but unburned site has the forest floor of 1.5cm thick. There were no significant differences in soil organic matter, total N, available P, exchangeable K, Ca, Na, and Mg, and CEC, pH in all soil depth, between unburned and burned sites after 3 days of forest fire and between burned site after 3 days and 8 months of forest fire, except in organic matter in 10～20cm soil depth in hardwood sites and in exchangeable Ca in the 10～20cm soil depth, and in Mg in the two soil depths in hardwood sites. It seems to be that forest fire had not changed the chemical soil properties in this study.

• Journal of Forest and Environmental Science
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• v.14 no.1
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• pp.1-13
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• 1998

In this paper, it has been discussed on the relation between the anatomical features of woods and the penetration of methyl methacrylate monomer system into major Korean tree species, especially the Pinus koraiensis, Larix leptolepis, Quercus mongolica and Tilia amurensis. 1. There was some differences in penetration of polymers among different tree species, but generally the penetration of ring porous woods seems to be larger than that of diffuse porous woods and it was very difficult to penetrate to Larix leptolepis, especially to the that of heart wood. 2. The penetration on transeverse surface was relatively easy but radial and tangential impregnation were somewhat hard and differences between them were negligible. 3. The penetration of sapwood was larger than that of heartwood and its differences varied according to the existence of tyloses or contents in vessel. 4. Generally the polymer penetration of earlywood was larger than that of latewood in ring porous woods, but on the contrary, penetration of earlywood was small than that of latewood on diffuse porous woods. 5. Vessel diameter of wood had nearly no relation to polymers penetration. This seems to come from the reason that effective vessel diameter varies with the existence of tyloses or contents in vessel. 6. The penetration of ray tracheids was larger than that of ray parenchyma cells in softwoods, but penetration of hardwood rays seems to be small in comparison with softwood ray parenchyma cells. 7. Specific gravity and annual ring width had no relation to the penetration of polymer.

• The Korean Journal of Mycology
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• v.26 no.2 s.85
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• pp.144-152
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• 1998

To obtain white rot fungi which have selective delignification capacity and can be used in biopulping processes, 94 different wood rotting fungi were screened and the capabilities of selected species were evaluated on deciduous and coniferous wood blocks. White rot fungi, first of all, were selected by simple enzyme tests, i.e., cellulase activity test; phenol oxidase activity test; laccase and peroxidase activity test. Most organisms that gave a positive Bavendamm gave a strongly positive laccase test with syringaldazine whereas most of those that gave a negative Bavendamm test also negative test for laccase and peroxidase, even if some exceptions were noted. Wood decay experiement were carried out to select fungal species with selective lignin-degrading ability by inoculating selected fungi to both wood blocks of Populus tomentiglandulosa and Larix leptolepis. After 12 weeks of incubation, weight losses, lignin losses, and morphological characteristics of the decayed wood were investigated. Almost all fungi tested caused 2 or more times of weight losses in P. tomentiglandulosa than in L. leptolepis, while no weight losses were detected from the un-inoculated wood blocks. Ceriporiopsis subvermispora and Phanerochaete chrysosporium were the best delignifiers for both hardwood and softwood. P. chrysosporium, however, was less effective than C. subvermispora. Bjerkandera adusta and two unidentified spp. caused delignification for only P. tomentiglandulosa. B. adusta caused simultaneous rot of all cell wall components, resulted in thinning of the secondary cell wall layers. Other fungi caused selective delignification resulting in the removal of lignin from middle lamella and separation of cells from each other.

• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.45-52
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• 1993

Surveyed results on the slope of grain and the twist of sawn lumber of Pinus koraiensis, Larix leptolepis, and Pinus densiflora were summarized as follows: 1. The slope of grain of Pinus koraiensis has a Z-grain in the stem axis. The slope of grain was found to be the lowest at near to the pith and then constantly increased. At the height of 0.2m from the base of stem. a cross section of 35 annual rings was found to have a repeatedly increasing and decreasing slope of grain and then constantly decreased. At the height of 1.2m to 7.2m from the base of stem, the slope of grain increased conspicuously until the 10th annual ring, after which it increased near to the bark with repeatedly increasing and decreasing trends. 2. Pinus densiflora has a S-grain in the stem axis. The lowest slope of grain was found at near to the pith, and the highest in the 10 to 35 annual rings from the pith. 3. Larix leptolepis has a S-grain. At the height of 3.2m from the base of stem, the big fluctuation of the slope of grain was found without any particular trend. 4. The slope of grain and the twist between natural and reforested timber of Pinus koraiensis were found to be almost the same trend in viewpoint of the annual ring. The maximum slope of grain of imported Siberian timber of Pinus koraiensis was found at the 10 annual rings, which was quite similar to that of native species in Korea, but the big difference of the twist was found at 140 annual rings. 5. The twist was little at the mature wood of reforested Pinus koraiensis and Siberians and the duplicated part of mature and juvenile woods of those. On the contrary, the twist was great at the duplicated part of mature and juvenile woods of Pinus koraiensis. 6. The twist of Larix leptolepis showed the S-direction which coincided with that of slope of grain. The twist was greatest at the part of juvenile wood and little at the duplicated part of mature and juvenile woods, and little difference of twist was found between mature and juvenile woods. 7. Siberian larix having a minimum slope of grain showed the lowest twist, and the twist at the duplicated part of mature and juvenile woods showed a middle level of both mature and juvenile woods' portions.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.531-536
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• 2009

Radial variations of ray spacing and frequency of biseriate ray were examined in the woods of most commercially important Korean softwood species of Pinus koraiensis and Larix kaempferi. Ray spacing, or ray number per mm in cross section, averaged 4.6 and 9.0 in Pinus koraiensis and Larix kaempferi, respectively. Thus, rays of Larix kaempferi appeared to be more closely arranged than those of Pinus koraiensis. Ray spacing was the densest around pith, and then slowly decreased toward bark. In tangential section, biseriate ray frequency of Larix kaempferi was higher than that of Pinus koraiensis. Biseriate ray was designated, based on the number of cells of biseriate portion in vertical extent, as the type of B+1 (one cell high), B+2 (two cells high), and so on. The dominated type was B+1 in Pinus koraiensis but B+2 in Larix kaempferi. The biseriate ray types of B+3, B+4, and B+5 were occasionally found in earlywood. Interestingly, even B+6 and B+7 types were observed in Larix kaempferi. In conclusion, it was considered that ray spacing could be used for separating juvenile wood from adult wood. Also, characteristics of ray spacing and biseriate ray might be used for identifying these two species.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.12-20
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• 2008

Radial and vertical variations of relative crystallinity and crystallite width of cellulose within stems of three softwoods (Pinus densiflora S. et Z., P. koraiensis S. et Z, P. rigida Mill.) grown in Korea were examined by an X-ray diffraction method. The mean of relative crystallinity was 61.7% in P. koraiensis, 60.6% in P. densiflora and 49.4% in P. rigida. The degree of crystallinity in earlywood and latewood increased with the age from pith to about 10~15 years, and then remained almost constant value. The relative crystallinitiy of latewood was slightly higher than that of earlywood. The relative crystallinity in P. densiflora was a little lower at the base of stem, but no significant difference by height was shown in P. koraiensis and P. rigida. The crystallite widths in the stems were 2.8 to 3.0 nm, but were not significantly different in earlywood and latewood by height. In conclusion, the relative crystallinity appeared to be a useful index for separating juvenile wood from adult wood in the softwoods of P. densiflora, P. koraiensis, and P. rigida grown in Korea.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.383-392
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• 1992

The objective of this study is to evaluate the impacts on the domestic timber supply potential of forest resources management policies such as the extention of forest management infrastruture and setting aside more forest lands for the provision of environmental goods. To this end, the domestic timber supply functions were estimated using time series data for the period 1970-1990 and were used to predict the future trends in timber production in the Republic of Korea. For this purpose, a set of scenarios based on the forest road density and forest inventory growth were designed for the next 40 years. The timber supply behavior in Korea was found to be different by species group : domestic supply of softwood roundwood is inelastic with respect to its ovum price while that of hardwood elastic. The effect of forest road construction on the domestic timber production seems to be insignificant yet. The model simulation aided by policy scenarios revealed that the future timber supply potential will be largely restricted if the policy option with emphasis on the provision of environmental goods from the forest resources were adopted.

• Journal of the Korean Wood Science and Technology
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• v.4 no.1
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• pp.15-20
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• 1976

This is the abstract of the study on the check by static driving nail in Pinus koraiensis Sieb. et Zucc., Abies holophylla Maximowicz, and Larix leptolepis Gordon Pinet. which are commercial woods and main forestation species in Korea. The static driving resistance of nail is decresed straightly and the surface and back check's length and width were increased in proportion to increase of the moisture content, but the surface check length and width were over twice as large as the back check, also the check were happened in order of Pinus koraiensis Sieb. et Zucc., Abies holophylla Maximowicz., and Larix leptolepis Gordon Pinet. As the driving nail speed was increased, surface check length and width were increased and the back check was over twice as large as the surface check.