• Journal of the Korean Wood Science and Technology
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• v.12 no.1
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• pp.31-37
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• 1984

For the modification of kiln drying schedule, relations between resistance to drying Rd and the moisture content or drying times were found for 4/4, 6/4 and 8/4 green Douglas fir heartwood by the mild drying schedule and the severe drying schedule until the average moisture content was about 10 percent. The results of this study were as follows. 1. Resistance to drying of thicker lumber was higher than that of thinner lumber and resistance to drying of three different thicknesses were negligible between the mild-and the severe drying schedule. The relationships between resistance to drying and two schedules or three thicknesses of lumber were $Rd_1=1.830{\times}10^5\;M^{-2.24}$ for 4/4 lumber by the mild drying schedule, $Rd_2=1.822{\times}10^5\;M^{-2.25}$ for 4/4 lumber by the severe drying schedule, $Rd_3=2.352{\times}10^5\;M^{-2.14}$ for 6/4 lumber by the mild drying schedule, $Rd_4=3.457{\times}10^5\;M^{-2.27}$ for 6/4 lumber by the severe drying schedule, $Rd_5=1.317{\times}10^6\;M^{-2.56}$ for 8/4 lumber by the mild drying schedule, $Rd_6=8.267{\times}10^5\;M^{-2.40}$ for 8/4 lumber by the severe drying schedule. 2. Thinner lumber exhibited lower level of moisture content and shorter drying time required at intersection point between the moisture content and resistance to drying as a function of drying time than those of thicker lumber. Drying time of mild drying was longer than that of severe drying and similar to the level of moisture content at intersection point.

• Journal of the Korean Wood Science and Technology
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• v.29 no.1
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• pp.1-8
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• 2001

Red pine (Pinus densiflora), white pine (Pinus koraiensis), larch (Larix leptolepis) and Western hemlock (Tsuga heterophylla) lumber were vacuum-press dried under three drying schedules to investigate current moisture contents (MC), drying rates and drying time factors related to five lumber thicknesses of 3, 5, 7, 9 and 11cm. Current MC could be estimated by drying factors such as lumber thickness, initial Me and drying time. Average drying rate from 30% to 15% Me was the highest for Western hemlock below fiber satuartion point, red pine, white pine and larch in the order of their magnitude. Drying rate curvilinearly decreased as lumber thickness increased. Drying time factor curvilinearly increased as lumber thickness increased.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.67-74
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• 1997

A relationship between drying resistance and moisture content was found for 24, 27 and 30mm thick boards, and 45, 51 and 57mm thick dimensions of Japanese larch. Dahurian larch and radiata pine in order to modify the kiln schedule by using time schedules. The amount of drying resistance for Dahurian larch lumber was the highest, and radiata pine lumber was the lowest, on the basis of the same moisture content range. Drying resistance increased curvilinearly as moisture content decreased, and was higher for thicker lumber than for thinner lumber, at a given moisture content. Combined drying resistance for the three board thicknesses and the three dimension thicknesses showed a comparatively strong for radiata pine and a Japanese larch, while a weak correlation for Dahurian larch as a function of two independent variables, thickness and moisture content of lumber, respectively.

• Journal of the Korean Wood Science and Technology
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• v.47 no.5
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• pp.557-566
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• 2019

Radial and tangential water diffusion in Eucalyptus globulus wood was investigated using three mature trees from a forest in Khemis Sahel (North Morocco). Absorption and desorption kinetics experiments were conducted at ambient temperature ($25^{\circ}C$) and $30^{\circ}C$, respectively, and a relative humidity of 60%. The diffusion coefficients in the two directions were determined under imposed hygrothermal conditions; they were greater in the radial direction for the absorption as well as desorption processes. Convective drying under load, preceded by reconditioning and followed up by balancing, revealed the drying conditions that corresponded to the appropriate drying schedules for E. globulus wood. This was verified by measuring the cracks and bowsbefore and after drying of boards.

• 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 the Korean Wood Science and Technology
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• v.29 no.4
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• pp.25-32
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• 2001

A microwave vacuum (MW/V) dryer was developed for drying short roundwoods, from which woodcraft souvenirs in Korean market are mostly made, and which were hardly dried without defects in a conventional kiln. It consisted of three 1.5 kW magnetrons of 2,450 MHz, a vacuum pump, a load cell of 100 kg and a cavity of $580{\times}580{\times}1,360\;mm^3$. A computer program was developed to switch on or off the magnetrons according to drying schedules, those were based on microwave injection time or the average of wood temperatures. To evaluate the new MW/V dryer the roundwood specimens of rigida pine, poplar and birch were dried. Their log diameters and lengths ranged from 125 to 25 em and from 25 to 50 cm, respectively. In spite of the presence of minor drying defects, the MW/V drying is found to be an effective method for drying short roundwoods. Wooden turneries made of red alder and ash logs were also MW/V dried from green to 4%MC without any degradation. The rates of the MW/V drying were examined for three different lengths of poplar logs.

• 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.19 no.2
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• pp.65-71
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• 1991

본 연구는 CCA 처리재의 재건조(再乾燥)시 적용된 건조 스케쥴 (통상(通常) 열기건조(熱氣乾燥)와 고온건조(高溫乾燥) 스케쥴)이 처리재의 휨강도(强度) 성질에 미치는 영향을 고찰하고자 수행되었다. 탄성계수(彈性係數)(MOE), 그리고 비파괴시험(非破壞試驗)에 의해 얻어진 동적(動的) 탄성계수 (Dynamic MOE) 및 대수감쇠율(對數減衰率)(Logarithmic decrement) 은 처리후 재건조에 의해 큰 영향을 받지 않았다. 반면에 적용된 건조 스케쥴에 관계없이 재건조시 심각한 파괴계수(破壞係數)(MOR)의 감소가 파괴계수 분포의 모든 영역에서 초래되었다. 그러나 통상 열기건조(최대 건구온도=$71^{\circ}C$)와 고온건조(건구온도=$110^{\circ}C$) 서로간에는 감소의 정도에 큰 차이가 없었다. 따라서, 처리재의 재건조사 심각한 파괴계수의 감소가 용인(容認)되지 않는다면 CCA로 처리된 Lodgepole pine 각재의 재건조는 미국 연방 임산물 시험장의 Lodgepole pine의 통상 열기건조 스케쥴 (T9-C3) 보다 온화(溫和)한 조건으로 실시되어야 할 것이다.

• Journal of the Korean Wood Science and Technology
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• v.2 no.2
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• pp.22-24
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• 1974

1. Object and importance of the research. The exports of plywood are increasing annually and it has ranked first in the world market because of the high quality product developed and manufactured using modern techniques. However, it is known that the exports of the other wood products, except plywood, is inactive because of their low quality. Accordingly, to increase the exports of various wood products investigations were carried out on kiln drying techniques to improve the quality of the wood. 2. The details and scope of the research Wet wood should be kiln dried before use to prevent various drying defects such as distortion, shrinkage etc, which would develop after processing, and also wet wood is not suitable for cutting, gluing and finishing. Therefore, the kiln drying properties of lumber from such species as Persimmon, Oak, Ramin and Meranti which are used in large quantity for manufacturing exporting wood products have been studied. Also the real state of kiln drying industry in Korea was investigated. 3. Results and proposal for practical use of the research 3. 1 Results of the research 3.1.1 The end checks and the time for drying from intial moisture content of about 40 percent to 5 percent moisture content in ovendry were investigated as Table 1. 3.1.2 The kiln dried results, for 30mm stock, which are presented by using kiln schedule Table 2 are as Table 3. 3.1.3 The kiln schedule for Persimmon which has a normal drying properties is given in Table 4. However, the persimmon which has easy checking properties should be air dried under a relative humidity of above 85% until reaching about 25 percent moisture content. 3.1.4 The kiln schedules for ramin, meranti and oak are given respectively as follows. Ramin kiln schedule ............ Table 5 and Table 6 Meranti kiln schedule ............ Table 7 Oak kiln schedule ............ Table 8 3.2 Proposal for practical use of the research Firms using the above species should be informed the results of the research so they can be used to preventing drying defects and shortening drying time.