• Journal of the Korean Wood Science and Technology
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• 제33권6호통권134호
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• pp.25-30
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• 2005

두께 50 mm 국산 소나무(Pinus densiflora Sieb. et Zucc.) 판재의 건조스케줄 개량을 위해 일반 열기 건조스케줄, 시간 기준 건조스케줄, 연속 온도상승 건조스케줄, 그리고 습구온도 조절 건조스케줄을 적용하여 최종함수율 15% 정도까지 건조한 후 각각의 건조스케줄 적용에 의한 건조특성을 비교분석하였다. 두께 50 mm 국산 소나무의 일반 열기 건조스케줄 적용실험 결과 건조속도는 0.53%/hr, 시간 기준 건조스케줄 적용에 의한 건조속도는 0.9%/hr, 그리고 연속 온도상승 건조스케줄 적용에 의한 건조속도는 2.29%/hr였으며, 습구온도 조절 건조스케줄 적용에 의한 건조속도는 1.52%/hr였다.

• Journal of the Korean Wood Science and Technology
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• 제18권1호
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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.

• 한국가구학회지
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• 제19권2호
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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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• 제10권1호
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• pp.38-48
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• 1994

강원도산(江原道産) 참나무과(科) 4수종(樹種)의 건조특성(乾燥特性)을 파악코져 $100^{\circ}C$에서 급속건조(急速乾燥)를 실시하여 건조중(乾燥中) 함수율(含水率)과 건조경과(乾燥經過), 초기할렬(初期割裂)(목구할렬(목구할렬(木口割裂))과 표면할렬(表面割裂)), 찌그러짐, 내부할렬(內部割裂) 등의 건조결함(乾燥缺陷)을 조사(調査)하여 추정건조(推定乾燥)스케쥴을 작성(作成)한 결과(結果)는 다음과 같다. 건조시간별(乾燥時間別) 건조중(乾燥中) 함수율(含水率)은 초기함수율(初期含水率)이 높은 판재(板材)일수록 급속(急速)한 곡선적(曲線的) 감소(減少)를 나타내었고 건조소요시간(乾燥所要時間)이 길었으며 굴참나무가 건조중(乾燥中) 할렬(割裂)의 발생량(發生量)이 가장 크게 나타났으며 구해진 추정건조(推定乾燥)스케쥴은 $T_5-C_2$였다. 또한 모든 수종(樹種)의 목리방향별(木理方向別) 수축율(收縮率)은 접선방향(接線方向)(T) > 방사방향(放射方向)(R) > 섬유방향(纖維方向)(L)의 순위(順位)였으며 급속건조법(急速乾燥法)에 의한 수축율(收縮率)이 정상적인 수축율(收縮率)보다 크게 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제15권2호
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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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• 제15권2호
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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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• 제17권3호
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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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• 제21권2호
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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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• 제12권1호
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• pp.1-12
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• 1996

강원도산(江原道産) 참나무과(科) 4수종(樹種)의 건조특성(乾操特性)을 파악코져 $100^{\circ}C$에서 급속건조(急速乾操)를 실시하여 건조중(乾操中) 함수율(含水率)과 건조경과(乾操經過), 초기할열(初期割裂)(목구할열(木口割裂)과 표면할열(表面割裂)), 찌그러짐, 내부할열(內部割裂) 등의 건조결함(乾操缺陷)을 조사하여 추정건조(推定乾操)스케쥴을 작성한 결과(結果)는 다음과 같다. 건조시간별(乾操時間別) 건조중(乾操中) 함수율(含水率)은 초기함수율(初期含水率)이 높은 판재일수록 급속(急速)한 곡선적(曲線的) 감소(減少)를 나타내었고 건조소요시간(乾操所要時間)은 두께가 두꺼울수록, 초기함수율(初期含水率)이 높을수록, 건조중(乾操中) 함수율(含水率) 변화( 變化)가 느린 수종(樹種)일수록 길었다. 또한, 두께가 두꺼울수록 할열(割裂)의 발생량(發生量)이 증가하므로 건조초기(乾操初期)의 조건(條件)을 완화하게 해야 함을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제35권1호
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• pp.11-16
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• 2007

본 연구는 통죽의 송풍오븐 건조중 수증기댐 처리가 건조속도 및 할렬과 외주할 예방에 미치는 영향을 조사하였다. 생재에서 함수율 약 7~8%까지 건조되는데 소요되는 시간은 건조스케줄이 과격할수록 적었으며, 건조소요시간은 건조초기의 건조속도에 의해서 크게 좌우되는 것으로 나타났다. 건조중 횡단면적 수축율과 통피층의 두께수축율은 모두 비정상적일 정도로 매우 크게 나타났다. 무처리재의 경우 건조개시 직후 할렬과 외주할이 발생하였으며, 수증기댐 처리재에서는 약 67% 정도의 건조수율을 기대할 수 있었다. 수증기댐 처리재의 외주할은 건조조건 보다는 수증기댐 처리에 의한 횡단면을 통과하는 수분의 증발 차폐정도와 밀접한 관련이 있는 것으로 평가되었다.