• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.25-30
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• 2005

This experiment was carried out for the improvement of drying schedules for 50 mm-thick Japanese red pine (Pinus densiflora Sieb. et Zucc.) lumber. Drying rates were analyzed comparatively after drying to 15% of final moisture content through the applications of conventional kiln drying schedule, time schedule, continuously rising temperature schedule, and drying rate schedule. As results drying rate of 50 mm-thick red pine lumber was 0.53%/hr with conventional kiln drying schedule, 0.9%/hr with time schedule, 2.29%/hr with continuously rising temperature schedule, and 1.52%/hr with drying rate schedule, respectively.

• Journal of the Korean Wood Science and Technology
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• v.18 no.1
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• pp.39-51
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• 1990

This research was carried out to offer the basis data for development of optimum drying schedule for a domestic oak species (Quercus grosseserrata B1.) by investigating drying rate. stress, defect, and moisuture gradient with board thicknesses and drying schedules (code number T4-C2 and T3-B1). The results were obtained as follows: 1. Average drying rate and total drying time from 52.2% to 5.8% were 0.105%/hr and 486 hours for drying schedule T4-C2 and those from 62.1% to 8.3% were 0.070%/hr. and 811 hours for drying schedule T3-B1. 2. Drying rates for 28mm- and 31mm-thick boards showed similar tendency, but were significantly different from 25mm- thick board in drying schedule T4-C2 and those for 22mm-, 25mm- 28mm- and 31mm-thick boards showed similar tendency but were significantly different from 19mm- thick boards in drying schedule T3-B1. 3. The moisture gradients for drying schedule T4-C2 were steeper than those for drying schedule T3-B1 during drying period. and especially in early drying stage slow slope of moisture gradients of drying schedule T3-B1 was effective in preventing serious problem of surface checks. 4. Drying stresses were lower in drying schedule T3-B1 than in drying schedule T4-C2 during drying period. 5. Drying schedule T4-C2 was appropriate for 25mm-thick board but not for 28mm- and 31mm-thick board because of strong drying condition. Drying schedule T3-B1 was appropriate for 28mm- and 31 mm-thick board but not for 19mm-, 22mm-, and 25mm-thick board because of weak drying condition.

• 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 Forest and Environmental Science
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• v.10 no.1
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• pp.38-48
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• 1994

This study was carried out to estimate drying schedule of Fagaceae four species grown in Kangwon-Do by oven-drying at $100^{\circ}C$ which aimed to elucidate the characteristics such as current moisture content, drying process, initial check, collapse and internal check during drying. The results were summerized as follows ; Current moisture content of each board showed a rapid drying curve with the hight initial moisture content of board and species with the high initial moisture content took long to do drying. Appearance of checks for Quercus variabilis were extremely severe and estimated schedule was $T_5-C_2$. The shrinkage rate of grain direction was in the order of tangential direction > radial direction > longitudial direction and the shrinkage rate of oven-drying at $100^{\circ}C$ was bigger than normal shrinkage rate.

• Journal of the Korean Wood Science and Technology
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• v.15 no.2
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• pp.113-119
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• 1987

A study was conducted to determine the kiln drying schedule for hydrid aspen, This kiln drying schedule was found by oven drying method and developed by pilot testing of 2.0cm, 2.5cm, 3.0cm-thick green lumber. The results of this study were as follows: 1. Kiln drying schedule developed by oven-drying method was $T_{12}-E_5$ for 2.5cm-thick green lumber. 2. Drying times for 2.0cm-thick green lumber(127.0 percent moisture content) to 7.3 percent moisture content, for 2.5cm-thick green lumber(95.0 percent moisture content) to 9.7 percent moisture content, and for 3.0cm-thick green lumber(118.5 percent moisture content) to 10.0 percent moisture content were 45 hours, 45 hours, and 54 hours, respectively. 3. Drying rate from 90 to 10 percent moisture content of 2.5cm-thick lumber was about 0.7 times faster than that of 2.0cm-thick lumber and about 1.1 times faster than that of 3.0em-thick lumber. 4. End checks for 2.0cm-, 2.5cm-, and 3.0cm-thick green lumber occurred 95, 74 and 100 percent moisture content, respectively and reached maximum amount in 53, 41, and 60 percent moisture content, respectively. 5. No surface check and no honeycomb occurred. 6. Cupping and collapse slightly occurred and the quality of dry lumber was first.

• Journal of the Korean Wood Science and Technology
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• v.15 no.2
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• pp.53-66
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• 1987

Korean red pine (Pinus densiflora S. et. Z.) and pitch pine(Pinus rigida Mill) $5{\times}10cm$ dimension lumber were dried in a kiln providing a cross-circulation velocity of 5 m/sec at dry-and wet-bulb temperatures of 116 and $71^{\circ}C$, followed by 3 hours at 91 and $85^{\circ}C$. Compared to dimension lumber dried lumber were as follows. 1. To dry to 10 percent moisture content, the high-temperatures schedule of Korean red pine and pitch pine lumber took less than one seventh the time required by the conventional kiln drying schedule. 2. High-temperature drying rate and conventional drying rate to 10 percent moisture content of Korean red pine lumber were 2.75 and 0.35%/hr, and those of pitch pine lumber were 3.38 and 0.46%/hr respectively. 3. Compared to lumber of both species on conventional schedule, moisture gradient of high-temperature lumber was greater. 4. Compared to lumber on conventional schedule, maximum surface checking of high-temperature lumber of both species was severer, and maximum end checking of high-temperature lumber of both species was similar to that of lumber on conventional schedule. 5. Compard to lumber on conventional schedule, Korean red pine lumber dried at high temperature showed more honeycombing, but pitch pine lumber dried at high-temperature showed significantly slighter honeycombing. 6. Compared to lumber on conventional schedule, the high-temperature lumber showed less warping lumber of both species. 7. Collapse and casehardening of Korean red pine and pitch pine lumber on both scheules were slight.

• 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.21 no.2
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• pp.39-48
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• 1993

End-matched disks of 7.7cm thickness were part-time dried in vacuum press dryer to investigate the drying characteristics by using drying schedules and end treatments. The ginkgo disks could be dried faster with severer end checks and ring failures by C schedule than by S schedule. There were no significant differences in drying rates and amounts of end checks, ring failures and V-shaped checks occurred between ginkgo disks end-taped with Korean traditional paper (KTP) and those untreated. The drying time of walnut disks was slightly reduced by end-taping with KTP. And the length of end checks and V-shaped checks and the frequency of defected disk were decreased more effectively than those untreated. The tangential strains and tangential drying stresses near bark sides of ginkgo and walnut disk untreated were developed in the early stage of drying and incresed slightly curvi-linearly above fiber saturation point (fsp) and more curvi-linearly below fsp. The influence of end-taping with KTP on the drying rate for impermeable walnut disk was stronger than that for permeable ginkgo disk.

• Journal of Forest and Environmental Science
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• v.12 no.1
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• pp.1-12
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• 1996

This study was carried out to estimate drying schedule of Fagaceae four species grown in Kangwon-Do by oven-drying at $100^{\circ}C$ which aimed to elucidate the characteristics such as current moisture content, drying process, initial check, collapse and internal check during drying following each board thickness (1.5cm, 2.5cm, 3.5cm, 4.5cm). The results were as follows; Current moisture content of each board showed a rapid drying curve with the high initial moisture content of board. With the high initial moisture content, the incease of board thickness and the slowness of changing rate of moisture content, species took long to do drying. Also, the initial conditions of drying had to be mild condition with the increase of board thickness.

• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.11-16
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• 2007

This study was carried out to investigate the effect of Vapor-dam treatment on drying drying rates, prevention of checks and V-shaped split during air circulating oven drying bamboo (Phyllostachys pubescens Mazel et Z) tube. It was shown that the drying time from green to around 7~8 % of moisture content was required less as drying schedule was more severe, and distinctly dominated by the drying rate during the initial drying stage. Area shrinkages in cross section and thickness shrinkages measured during air circulating oven drying test were very large. Surface checks and V-shaped splits were occurred in untreated samples just after the beginning of drying, while sixty seven percentages of all the Vapor-dam treated samples could be produced without drying defects. The V-shaped splits occurred in the Vapor-dam treated samples were influenced more by the sealing of the vapor evaporation through the cross section than drying schedule.