• Journal of the Korean Wood Science and Technology
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• v.23 no.3
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• pp.1-7
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• 1995

The crystal transformation from cellulose I to cellulose II during alkaline swelling of waste wood, which has been used for cultivating oak mushroom(Cortinellus edodes (Berk.) Ito et Imai), was investigated and compared to that of normal wood by a series of X-ray diffraction analysis. When the sapwood of cultivated wood was treated with 20% NaOH solution for 2 hours, the cellulose I can be easily transformed into Na-cellulose I than normal wood or heartwood of cultivated wood. Certainly the formation of Na-cellulose in wood is proportional to alkali swelling duration, and the formation of cultivated sapwood was faster than that of the other woods. Cellulose I in the sapwood of cultivated wood was easily transformed into cellulose II during mercerization, but the sapwood of normal wood and the heartwood of cultivated wood hardly converted to cellulose II. Namely, most of Na-cellulose I in normal wood can be reconverted to cellulose I in the process of washing and drying. Therefore, it can be concluded from this study that in cell wall lignin and hemicellulose can prevent the alkaline swelling of cellulose in wood and the transformation from cellulose I to cellulose II as well.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.17-26
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• 2007

This study was conducted to investigate the effects of End-coating (CO) treatment and Vapor-dam (V) treatment on the air circulating oven drying characteristics of green stock (Paulownia tomentosa) for drum. The reduction of the weight of specimens was greatly displayed in order of control (C-NC) treatment, End-coating (C-CO) treatment, Vapor-dam (V-NC) treatment and Vapor-dam/End-coating (V-CO) treatment after the beginning of drying. The V-CO treated specimen showed smoother temperature gradient compared with the V-NC treated specimen throughout whole drying stage and there was little temperature gradient between the inner and outer part of the cylindrical stock. The C-CO treated specimen showed higher value of vapor pressure in both the inner and outer part of the cylindrical stock until the middle stage of drying, while after the middle stage of drying only the inner part of the cylindrical stock presented higher value compared with the C-NC treated specimen. The distribution of the absolute vapor pressure of the V-CO treated specimen was similar to that of the V-NC treated specimen during the initial stage of drying. However, the former showed a large distribution in order of the hollow, the outer part, the inner part of the cylindrical stock after the initial stage of drying, which was entirely different model of distribution from that of the V-NC treated specimen. Surface checks and ring failures were not observed for all of the specimens, while end checks were severely occurred for the C-NC treated specimen and the V-NC treated specimen.

• Journal of Conservation Science
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• v.28 no.2
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• pp.95-99
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• 2012

The compressive strength of PEG along processing concentration and solvent is willing to be measured and proper processing condition for exhibition and storage is also willing to be measured by comparing with dimensional stability. In the advanced research of setting PEG-preprocessing concentration & solvent for freeze drying of waterlogged archaeological wood of high water content, vacuum freeze drying showed the highest dimension stability after 40% PEG-preprocessing of aqueous solution. In this study, the compressive strength increased in proportion of processing concentration and water showed the relatively-higher compressive strength than t-butanol regarding solvent. Especially, it showed that there is no big strength difference between PEG 40% and PEG 50% in aqueous solution by 6.6%(16kgf/$cm^2$). According to the above results, it was recognized that it is most effective to implement freeze drying after 40% PEG-preprocessing when want to dimensional stability and compressive strength simultaneously.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.50-57
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• 2004

This study attempted to evaluate the water repellency and drying effectiveness of linseed oil treated-solid wood at high temperature by immersion. The moisture content of green wood (Pinus densiflora) sample (above 90%) was reduced about 10% after 6 hours treatment at 150℃. When the treated samples were cut into cross section along the length, it was observed that the linseed oil penetrated into up to 20% of the sample cross section area in all locations. However, a strength loss of the specimen was not detected. The pre-drilling before linseed oil treatment was effective in reducing the defects such as checks and splits, and improved the linseed oil penetration into all samples from the surfaces. The result of water absorption test of treated-wood showed that the water repellent efficacy of treated-wood was greater than that of the control. The anti-fungal activity of treated samples using five sap stains and thee decay fungi was not detected in broad-spectrum toxic mechanism. However, decay test using white rot fungi (Tyromyces palustris) and brown rot fungi (Trametes versicolor) showed that the treated sample has a decay resistance to these two fungi.

• Journal of the Korea Furniture Society
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• v.19 no.2
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• pp.116-123
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• 2008

Kiln schedule development was based on two schedule phases, the first being to determine the maximum safe kiln temperature during the check prone initial stage of drying, with the second stage determining how to accelerate drying once the danger of checking had passed. This was achieved by using 38 mm thick boards which were pre-screened for susceptibility to internal checking, and then drying matched sample boards over a range of kiln temperatures. Research has shown that below 50% MC there is no further risk of internal checking. However, difference in drying rate due to board width and the increased occurrence of wet patches in wide boards means that it is essential to modify the basic schedule according to the maximum board width. A condition of 52/40 $^{\circ}C$ was selected for the checking-free initial kiln drying step and a 5-step kiln-schedule dried the boards from 109% to 8% MC for 72.5 hours without internal checking.

• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.10-39
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• 1988

This study investigated the temperatures and relative humidities in the semi-greenhouse type solar dryer with a black rock-bed heat storage and without heat storage and outdoor temperature and relative humidity at 9 a.m. and 2 p.m.. A comparison was made of the drying rates, final moisture contents, moisture content distributions, casehardening stresses, drying defects, volumetric shrinkage of dried lumber for solar- and air-drying from the green condition of mixtures of Douglas-fir, lauan, taun, oak and sycamore 25mm- and 50 mm-thick lumber during the same period for four seasons, and heat efficiencies for solar dryer with and without the heat storage for saving of heat energy and the cost of lumber drying using the solar energy. The results from this study were summarized as follows: I. The mean weekly temperatures in the solar dryers were 3 to $6^{\circ}C$ at 9 a.m. and 9 to $13^{\circ}C$ at 2 p.m. higher than mean outdoor temperature during all the drying period. 2. The mean weekly relative humidities in the solar dryers were about 1 to 19% at 9 a.m. higher than the outdoor relative humidity. and the difference between indoor and outdoor relative humidity in the morning was greater than in the afternoon. 3. The temperatures and relative humidities in the solar dryer with and without the heat storage were nearly same. 4. The overall solar insolation during the spring months was highest and then was greater in the order of summer, atumm, and winter month. S. The initial rate of solar drying was more rapid than that of air drying. As moisture content decreased, solar drying rate became more rapid than that of air drying. The rates of solar drying with and without heat storage were nearly same. The drying rate of Douglas-fir was fastest and then faster in the order of sycamore, lauan, taun and oak. and the faster drying rate of species, the smaller differences of drying rates between thicknesses of lumber. The drying rates were fastest in the summer and slowest in the winter. The rates of solar drying during the spring were more slowly in the early stage and faster in the later stage than those during the autumn. 6. The final moisture contents were above 15% for 25mm-thick air dried and about 10% for solar dried lumber, but the mean final MCs for 50mm-thick lumber were much higher than those of thin lumber. The differences of final MC between upper and lower course of pile for solar drying were greater than those of pile for air drying. The differences of moisture content between the shell and the core of air dried lumbers were greater than those of solar dried lumber, smallest in the drying during summer and greatest in the drying during winter among seasons. 7. Casehardening stresses of 25mm- and 50mm-thick dried lumber were slight, casehardening stress of solar dried lumber was severer than that of air dried lumber and was similar between solar dried lumber with and without heat storage, Casehardening stresses of lumber dried during spring were slightest and then slighter in the order of summer, autumn, and winter. Casehardening stresses of Douglas -fir, sycamore and lauan were slight, comparing with those of taun and oak. 8. Maximum initial checks of 25mm-thick lumber occurred above and below fiber saturation point and those of 50mm-thick lumber occurred in the higher moisture content than thin lumber. As the moisture content decreased, most of checks were closed and didn't show distinct difference of the degree of checks among drying methods. The degree of checks were very slight in case of Douglas-fir and lauan, and severe in case of taun and oak. The degree of checks for 50mm-thick lumber were severer than those for 25mm-thick lumber. 9. The degree of warpage showed severe in case of oak and sycamore lumber, but no warping was found in case of Douglas-fir, lauan and taun. 10. The volumetric shrinkages of taun and oak were large and medium in case of Douglas-fir, lauan and sycamore. 11. Heat efficiencies of solar dryer with heat storage were 6.9% during spring, 7.7% during summer, 12.1% during autumn and 4.1% during winter season. Heat efficiency of solar dryer with heat storage was slightly greater than that of without heat storage. As moisture content of lumber decreased, heat efficiency decreased.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.67-81
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• 1989

This experiment was carried out to know the mothod of changing the step of moisture content schedule with time in conventional kiln drying. For the purpose of this object. we made drying model by applying the moisture diffusion model by J.FSiau(1984) to average moisture content equation by J.Crank(1956) derived it from Fick's second law. And to verify this method of drying model. 2.5cm-thick boards and 5.0cm-thick dimension lumbers of Pinus densiflora were kiln-dried with the schedule of T11-C3 and T10-C4, respectively. And then the drying rates were investigated and compared with those calculated from drying model. The results obtained were as follows 1. Average drying rate and total drying time of board to dry to 6.5% moisture content were 0.64%/hr and 109hr., and those of dimension lumber to dry to 8.3% moisture content were 0.4%/hr. and 162hr., respectively. 2. The moisture content of shell and core decreased by equalizing treatment and increased by conditioning treatment both on board and dimension lumber. But the moisture gradient was lower after conditioning than after equalizing. 3. As the drying was proceeded, the transverse bound water diffusion coefficient all but linearly decreased, the water vapor diffusion coefficient abruptly curvilinearly increased, while the transverse diffusion coefficient curvilinearly decreased both on board and dimension lumber. But each of diffusion coefficients on board was larger than that on dimension lumber. 4. Compared to experimential drying rate of board. theoretical drying rate was larger at 30.0%-21.8% moisture content range and was similiar at 21.8%-5.4% moisture content. And in case of dimension lumber, the drying rate was similiar at 30.0%-16.1% moisture content range but theoretical drying rate was much lower at 16.1%-8.3% moisture content range. 5. The possibility of adapting this drying model to changing the moisture content schedule step with time was in the range of 21.8%-5.4% moisture content on board. And in the case of dimension lumber that was in the range of 30.0%-16.1% moisture content.

• 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 Korean Society of Forest Science
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• v.97 no.6
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• pp.570-575
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• 2008

This study was carried out to provide basic information on physiological changes of 4-year-old seedlings of Pinus thunbergii inoculated with pine wood nematodes by analyzing changes of symptom development, stem and needle water content and nematode populations in stem. Twenty days after inoculation, needles were discolored as an external symptom, and xylem drying and pith browning occurred at the above and below of the inoculation sites as an internal symptom. However, xylem drying began to occur 10 days after inoculation, which was determined by the difference in drying status of xylem and cortex between control and inoculated seedlings. Although population of pine wood nematode increased from 5 to 10 days after inoculation, it has increased dramatically from 10 to 20 days after inoculation when both internal and external symptoms appeared. As the time passed by after inoculation with pine wood nematodes, water content of stem and relative water content in current needles and branch gradually decreased. As the number of nematodes increases, water content of stem and relative water content of current needles and branches decreased significantly. There was a positive relationship between the number of nematodes and xylem drying and/or disease development, but the number of nematodes rapidly decreased as seedlings become severely diseased.

• Journal of the Korean Wood Science and Technology
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• v.29 no.1
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• pp.52-59
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• 2001

The fixation characteristics of CCA and CCFZ in Japanese red pine, Japanese larch, and ezo spruce sapwood were compared at various temperatures and fixation conditions (drying and nondrying fixation). Fixation was monitored by the rates of reduction of hexavalent chromium to trivalent one, and optimal fixation time was estimated based on the results. The rate of fixation was highly temperature dependent, and the fixation rate of treated wood conditioned under nondrying conditions was much more faster than that under drying conditions, especially when the moisture content of treated wood was below fiber saturation point. Preservative types affected fixation; CCA-Type B had the highest fixation rate, followed by CCA-Type C and then CCFZ. The differences in fixation rates of preservative components were also observed among wood species; Japanese red pine fixed the fastest, followed by Japanese larch and then ezo spruce. Time required to complete fixation according to the fixation temperature could be predicted successfully using the regression equations between the temperatures and fixation time, regardless of conditioning methods, preservative types, and wood species.