• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.23-30
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• 2007

Round piles of Korean larch were excavated from the foundation of ex-Chosunchongdokbu (ex-Chosun Governer-General Building), which was constructed in 1916 and dismantled later in 1996. By the record (Huh, 1996), the Korean larch logs were logged from the Yalu river area near Mt. Baekdu in North Korea. At present, however, Korean larch is not so popular in South Korea. The latewood ratio profiles and strength properties (longitudinal compression, shear, longitudinal tensile, and bending) were obtained. The ratio of latewood from pith to bark increased up to 25 years, and then it showed constant tendency at 40% with some variances. From the microscopic observation, however, the latewood ratio decreased from the heartwood to the sapwood. Compression strength was greater and bending strength was a little lower than the previous reports (references 13~15), which might be attributed to the strength reduction of old structural members by aging or damage in the compression specimens than the bending ones. The flat-grained specimens for the shear and tension test showed higher coefficient of variation (COV) than the edge-grained ones. For the better comparison of results, in case of shear and tensile strength tests, the strength values of the edge-grained specimens were thought to be adopted rather than those of flat-grained ones.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.513-526
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• 2020

The existing preservation methods are difficult to be applied to a large dimension log which is needed for making traditional wooden ship 'Jalur' in Riau Province. Novel techniques to provide the use of readily available species to replace traditional species alternative were investigated. These included infusion and a combination of injection and bandage-wrapping methods for preserving living trees of Balam (Macaranga conifera (Rchb.f. & Zoll.) Müll.Arg.) and Bintangor (Calophyllum soulattri Burm.f.). Water-based boron compounds were applied as wood preservatives. In total, 18 discs from the bottom, middle, and top of four trees and two controls were used. Trees undergoing treatment were also used to see how wood anatomical structure might affect the boron penetration. The overall aim was to identify the best method for use in Jalur manufacturing. The results showed that in infused Balam tree where the hose position for the preservative intake was deep (10-15 cm from the bark), no boron compound was observed in the outer sapwood. Combination of injection and bandage-wrapping method gave higher percentage of boron penetration at bottom and middle of Balam tree. However, infused Bintangor showed 100% boron penetration. The larger vessel diameter, the absence of tyloses, and the simple perforation plates in Bintangor wood were likely to have contributed to the higher penetration of boron. The combination of bandage-wrapping and infusion, or alternatively by infusing the living trees close to the bark, and at as low as position in the stem gives better protection when treatments are applied to living trees.

• Journal of the Korean Wood Science and Technology
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• v.14 no.1
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• pp.45-54
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• 1986

A study was conducted to determine the physical properties related to drying characteristics, the seasonal air drying curves and the kiln drying schedule for taun lumber imported and utilized. This kiln drying schedule was found by oven drying and developed by pilot testing of green lumber and partially air dried lumber. The results of this study were as follows; 1. Average green specific gravity and standard deviation of heartwood lumber were 0.60${\pm}$0.03 and those of sapwood lumber were 0.64${\pm}$0.02. 2. Radial shrinkage from green to air dry and from green to oven dry were 3.05 percent and 5.96 percent respectively, and tangential shrinkage from green to air dry and to oven dry were 5.49 percent and 8.74 percent respectively. 3. Drying time for 25mm thick green lumber (50 percent moisture content) air dried to 30 percent moisture content were 14 days in springtime. 6 days in summertime, and 12 days in autumntime, whereas for 50mm thick lumber in 36 days in springtime, 18 days in summertime, 38 days in autumntime. 4. Kiln drying schedules developed by oven drying were T8-B3 for 25mm thick lumber and T5-B2 for 50mm thick lumber. 5. Kiln drying curves of green 25mm and 50mm thick lumber were similar to those of partially air dried lumber from the level of 30 percent average moisture content. Green 25mm thick lumber (55.7 percent moisture content) was dried to 9.3 percent moisture content in 101.5 hours and green 50mm thick lumber (65.6 percent moisture content) was dried to 11.5 percent moisture content in 526 hours. 6. End checking for green 25mm thick lumber occured in 49.6 percent moisture content and reached maximum amount in 27.6 percent moisture content and closed in 15.8 percent moisture content. 7. End checking for green 50mm thick lumber and partially air dried lumber developed and reached maximum amount earlier then for 25mm thick lumber. 8. Final moisture content of surface layer for 50mm thick lumber was one half of that of core, and moisture content equalized in the lumber after nine days of room conditioning. 9. Casehardening for 50mm thick lumber was slight and was conditioned after nine days of room stroage. 10. Drying defects, such as end checking and surface checking, were not observed and the quality of dry lumber was first.

• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.330-339
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• 2009

The material properties of Cedar (Cryptomeria japonica) were evaluated according to heat treatment conditions. The special focus was made on the color control of cedar wood by heat treatment. The difference of color between sapwood and heartwood could be reduced by heat treatment at a temperature above $170^{\circ}C$. Long heating time was more effective in reducing the difference. The Equilibrium Moisture Content (EMC) of heat-treated wood was as low as 50 percent. The result obviously indicates that heat-treated wood is more dimensionally stable in the change of moisture condition than the control. The heat-treated wood was also effective in increasing the durability against wood rotting fungi. However, more study is required to develop heat treatment as an environmentally-friendly technology for wood preservation without chemical. The mechanical properties of heat-treated wood showed relatively higher performance than the control in general. Meanwhile the dramatic decrease in impact bending stress due to the loss of ductility may limit uses of heat-treated wood in certain cases. There were no significant changes in microscopic structure which may cause changes in mechanical properties. Further study on the chemical analysis of heat-treated wood is needed to scrutinize the causes of changes of material properties.

• Research in Plant Disease
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• v.18 no.2
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• pp.101-108
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• 2012

In 2006, pinewood nematode, Bursaphelenchus xylophilus, was isolated from about 50 years old trees of Pinus densiflora and P. koraiensis showing leaf-wilt and -drying symptoms in Gwangju, Gyeonggi-do and Chuncheon, Gangwon-do. Isolation of pinewood nematodes from sapwood of infected pine trees showed no difference in population density between tree species and among the sampling heights on the main stem. Migration of pinewood nematodes in the host tree were investigated by inoculation of red pine (P. densiflora, 3 years old) seedlings with B. xylophilus. The nematodes seemed to move in red pine seedlings prior to multiplication and it might have taken about 20 days to start multiplication and expression of symptoms including wilt and dieback. In initial time after inoculation, nematodes started migration through the cortical resin canal from inoculated site and further showed upward and downward movements. More nematodes were observed in cortical resin canal during early period of inoculation and later in resin canal of xylem and tracheid also while, the pith still remained free from nematode. The density of B. xylophilus was higher in seedlings of low-vigor with poor root growth than in seedlings of normal root growth. Seedlings showing high density of B. xylophilus exhibited stem discoloration and secondary infection by fungus at the inoculation site.

• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.234-253
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• 2021

The Quercus mongolica has a high utilization value in industrial economic sector. The species is distributed throughout Korea, however, the damage caused by deterioration such as discoloration and decay is severe. For this reason, the deterioration of Q. mongolica is an obstacle to its use as wood, but research on deterioration factors is insufficient. In this study, we focused on fungi as a factor influencing the deterioration of Q. mongolica, and isolated and identified the fungi from the deteriorated Q. mongolica. In additions, in order to confirm whether the identified fungi actually affects wood deterioration, enzyme activities of the identified fungi were evaluated and related mass loss of wood treated with the fungi was measured by wood decay test. As a result of sequencing analysis using the ITS region of the genomic DNA of the fungi isolated from Q. mongolica, Mucor circinelloides, Cunninghamella elegans, and Umbelopsis isabellina 3 species belonging to Mucoromycota phylum, and Ophiostoma piceae and Aureobasidium melanogenum 2 species belonging to Ascomycota phylum were identified. These five fungi had enzyme (i.e. cellulase, laccase) activities related to wood decay and reduced the mass of heartwood and sapwood of Q. mongolica in practice. In particular, O. piceae and A. melanogenum, which have both cellulase and laccase activities, showed 6.9% and 1.5% mass loss, respectively. These results indicated that five fungi identified in this study influence the deterioration of Q. mongolica and are wood decaying fungi for Q. mongolica potentially.

• Journal of the Korean Wood Science and Technology
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• v.30 no.4
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• pp.27-32
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• 2002

We investigated the effect of polyethylene glycol(PEG) treatment of preservative treated green japanese cedar(Cryptomeria japonica) round posts on their preservative penetration and check formation during the air drying. The round rods were dip-treated in 10% preservative solution of Basilit CFK for 1 day, followed by application(3, 5, and 10 times) with 50% PEG-400 solution, and then dried for 30 days under natural conditions. The rate of preservative penetration into sapwood was a low by 23.2% without PEG treatment, whereas that was a high by about 51.2~64.5% with PEG treatment. From these results, it was assumed that PEG played an affirmative role in the penetration of preservative components loaded onto the surface of round rods by dipping. During the air drying, the formation of drying checks decreased significantly with increasing application times of PEG. Even though some drying checks in PEG treated rods were developed, the number and size of checks was reduced remarkably by PEG treatment. After 2 months of outdoor exposure, PEG treatment failed to reduce checking in preservative-treated rods whereas finishing of polyurethane resin lacquer after PEG treatment was significantly effective in preventing check development.

• Journal of the Korean Wood Science and Technology
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• v.10 no.3
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• pp.13-44
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• 1982

1. Since long time ago, it has been talked about that soaking wood into water for a long time would be profitable for the decreasing of defects such as checking, cupping and bow due to the undue-shrinking and swelling. There are, however, no any actual data providing this fact definitly, although there are some guesses that water soluble extractives might effect on this problem. On the other hand, this is a few work which has been done about the effect of water soluble extractives upon the some physical properties of wood and that it might be related to the above mentioned problem. If man does account for that whether soaking wood into water for a long time would be profitable for the decreasing of defects due to the undue-shrinking and swelling in comparison with unsoaking wood or not, it may bring a great contribution on the reasonable uses of wood. To account for the effect of water soluble extractives upon physical properties of wood, this study has been made at the wood technology laboratory, School of Forestry, Yale university, under competent guidance of Dr. F. F. Wangaard, with the following three different species which had been provided at the same laboratory. 1. Pinus strobus 2. Quercus borealis 3. Hymenaea courbaril 2. The physical properties investigated in this study are as follows. a. Equilibrium moisture content at different relative humidity conditions. b. Shrinkage value from gre condition to different relative humidity conditions and oven dry condition. c. Swelling value from oven dry condition to different relative humidity conditions. d. Specific gravity 3. In order to investigate the effect of water soluble extractives upon physical properties of wood, the experiment has been carried out with two differently treated specimens, that is, one has been treated into water and the other into sugar solution, and with controlled specimens. 4. The quantity of water soluble extractives of each species and the group of chemical compounds in the extracted liquid from each species have shown in Table 36. Between species, there is some difference in quantity of extractives and group of chemical compounds. 5. In the case of equilibrium moisture contents at different relative humidity condition, (a) Except the desorption case at 80% R. H. C. (Relative Humidity Condition), there is a definite line between untreated specimens and treated specimens that is, untreated specimens hold water more than treated specimens at the same R.H.C. (b) The specimens treated into sugar solution have shown almost the same tendency in results compared with the untreated specimens. (c) Between species, there is no any definite relation in equilibrium moisture content each other, however E. M. C. in heartwood of pine is lesser than in sapwood. This might cause from the difference of wood anatomical structure. 6. In the case of shrinkage, (a) The shrinkage value of the treated specimen into water is more than that of the untreated specimens, except anyone case of heartwood of pine at 80% R. H. C. (b) The shrinkage value of treated specimens in the sugar solution is less than that of the others and has almost the same tendency to the untreated specimens. It would mean that the penetration of some sugar into the wood can decrease the shrinkage value of wood. (c) Between species, the shrinkage value of heartwood of pine is less than sapwood of the same, shrinkage value of oak is the largest, Hymenaea is lesser than oak and more than pine. (d) Directional difference of shrinkage value through all species can also see as other all kind of species previously tested. (e) There is a definite relation in between the difference of shrinkage value of treated and untreated specimens and amount of extractives, that is, increasing extractives gives increasing the difference of shrinkage value between treated and untreated specimens. 7. In the case of swelling, (a) The swelling value of treated specimens is greater than that of the untreated specimens through all cases. (b) In comparison with the tangential direction and radial direction, the swelling value of tangential direction is larger than that of radial direction in the same species. (c) Between species, the largest one in swelling values is oak and the smallest pine heartwood, there are also a tendency that species which shrink more swell also more and, on the contrary, species which shrink lesser swell also lesser than the others. 8. In the case of specific gravity, (a) The specific gravity of the treated specimens is larger than that of untreated specimens. This reversed value between treated and untreated specimens has been resulted from the volume of specimen of oven dry condition. (b) Between species, there are differences, that is, the specific gravity of Hymenaea is the largest one and the sapwood of pine is the smallest. 9. Through this investigation, it has been concluded that soaking wood into plain water before use without any special consideration may bring more hastful results than unsoaking for use of wood. However soaking wood into the some specially provided solutions such as salt water or inorganic matter may be dissolved in it, can be profitable for the decreasing shrinkage and swelling, checking, shaking and bow etc. if soaking wood into plain water might bring the decreasing defects, it might come from even shrinking and swelling through all dimension.

• Journal of the Korean Wood Science and Technology
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• v.7 no.2
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• pp.3-30
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• 1979

Larch ($\underline{Larix}$ $\underline{leptolepis}$ GORDON), one of the major afforestation species in Korea in view of its growing stock and rate of growth, is not favored as a raw material for pulp due to its low yield of pulp and difficulties with bleaching arising from the high content of extractives in wood, and the high heartwood ratio and the active phenolics, respectively. The purpose of this study is to investigate the characteristics of firstly pulping with various additives of cellulose protector for the yield of pulp, and secondly bleaching with oxygen for chlotination-alkali extraction of five stage-sequence to reduce chlorine compounds in bleaching effluents. The kraft cooking liquor for five age groups of larchwood was 18 percent active alkali with 25 percent sulfidity and 5 : 1 liquor-to-wood ratio, and each soda liquor for sap-and heart-wood of the 15-year-old larchwood was 18 percent alkali having one of the following cellulose protectors as the additive; magnesium sulfate ($MgSO_4$, 2.5%), zinc sulfate ($ZnSO_4$, 2.5%), aluminium sulfate ($Al_2(SO_4)_3$, 2.5%), potasium iodide (KI, 2.5%), hydroquinone (HQ, 2.5%), anthraquinone (AQ, 0.1%) and ethylene diamine (EDA, 2.5%). Then each anthraquinone-soda liquor for the determination of suitable cooking condition was the active alkali level of 15, 17 and 19 percent with 1.0, 0.5 and 0.1 percent anthraquinone, respectively. The cooking procedure for the pulps was scheduled to heat to 170$^{\circ}C$ in 90 minutes and to cook 90 minutes at the maximum temperature. The anthraquinone-soda pulps from both heartwood and sapwood of 15-year-old larchwood prepared with 0.5 percent anthraquinone and 18 percent active alkali were bleached in a four-stage sequency of OCED. (O: oxygen bleaching, D: chlorine dioxide bleaching and E: alkali extraction). In the first stage oxygen in atmospheric pressure was applied to a 30 percent consistency of pulp with 0.1 percent magnesium oxide (MgO) and 3, 6, and 9 percent sodium hydroxide on oven dry base, and the bleached results were compared pulps bleached under the conventional CEDED (C: chlorination). The results in the study were summarized as follows: 1. The screened yield of larch kraft pulp did not differ from particular ages to age group, but heartwood ratio, basic density, fiber length and water-extractives contents of wood and the tear factor of the pulp increased with increasing the tree age. The total yield of the pulp decreased. 2. The yield of soda pulp with various chemicals for cellulose protection of the 15-year-old larchwood increased slightly more than that of pure soda pulp and was slightly lower than that of kraft pulp. The influence of cellulose protectors was similar to the yield of pulps from both sapwood and heartwood. The effective protectors among seven additives were KI, $MgSO_4$ and AQ, for which the yields of screened pulp was as high as that of kraft pulp. Considering the additive level of protector, the AQ was the most effective in improving the yield and the quality of pulp. 3. When the amount of AQ increased in soda cooking, the yield and the quality of the pulp increased but rejects in total yield increased with decreasing the amount of active alkali from 19 to 15 percent. The best proportion of the AQ seemed to be 0.5 percent at 17 percent active alkali in anthraquinone-soda pulping. 4. On the bleaching of the AQ-soda pulp at 30 percent consistency with oxygen of atomospheric pressure in the first stage of the ODED sequence, the more caustic soda added, the brighter bleached pulp was obtained, but more lignin-selective bleaching reagent in proportion to the oxygen was necessary to maintain the increased yield with the addition of anthraquinone. 5. In conclusion, the suitable pulping condition for larchwood to improve the yield and quality of the chemical pulp to the level for kraft pulp from conventional process seemed to be. A) the selection of young larchwood to prevent decreasing in yield and quality due to the accumulation extractives in old wood, B) the application of 0.5 percent anthraquinone to the conventional soda cooking of 18 percent active alkali, and followed, C) the bleaching of oxygen in atmospheric pressure on high consistency (30%) with 0.1 percent magnesium oxide in the first stage of the ODED sequence to reduce the content of chlorine compounds in effluent.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.23-32
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• 2008

Anatomical and physical characteristics of seven cultivars of chestnut wood (Castanea crenata Sieb. et Zucc.), Tanzawa, Ibuki, Mansung, Arima, Ginyose, Tsukuba, and Riheiguri, were investigated to obtain some valuable information for their possibilities to be used for high quality furnitures and woodcrafts. Solitary pore and figured-porous or ring-porous wood types were observed in wide growth rings, and ring-porous in narrow growth rings. Procumbent type was prevalent in ray cells although upright and square types were scarcely existed. Uniseriate, biseriate, and multiseriate rays were observed in tangential section. Uniseriate ray was abundant near the pith, and biseriate and multiseriate rays were frequently existed near the bark. The occurrence rate of biseriate and multiseriate rays was significantly high in Tanzawa, Ibuki, Mansung and Tsukuba, but was somewhat low in Arima, Ginyose and Riheiguri. The inner region showed larger vessel diameter, more vessel number, fewer ray number and higher ray height than the outer region. Growth-ring width in inner region was larger than that in outer region. Growth-rings in inner region of Mansung and Arima were wide while that of Ibuki was narrow. Outer region in all cultivars showed higher latewood percentage than inner region. Especially, Mansung and Tsukuba showed significantly high latewood percentage in their outer region. Green moisture content and density of heartwood were higher than those of sapwood. Tsukuba and Riheiguri had higher green moisture content, and Ibuki and Riheiguri had higher green density than the other chestnut cultivars.