• Journal of the Korean Wood Science and Technology
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• 제20권1호
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• pp.5-14
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• 1992

Experimental external collector type solar lumber dryer of $1m^3$ of maximum capacity with $1.6m^3$ of collector area was designed and constructed. The seasonal performance of solar dryer, including air-conditions, energy efficiency, and drying characteristics of 3cm-thick red pine and douglas-fir lumber was investigated. Also, the economic analysis was carried out. Annual average solar drying rate was about 2 times faster than air-drying rate with no significant difference in the amount of drying defects. But in initial drying stage air-drying rate in winter was much faster and those in spring and autumn were slightly slower than solar drying rate in each season. Annual average energy efficiency of solar-dryer and-collector was 25% and 57%, respectively. Fuel savings were over 50% at 15% of energy inflation rate and the payback period was estimated as 6.10 years at 30% of energy inflation rate.

• Journal of the Korean Wood Science and Technology
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• 제31권6호
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• pp.22-30
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• 2003

This study was performed to obtain the basic data for high quality timber production and efficient utilization by investigating the effect of pruning on timber quality of domestic plantation-grown Korean pine (Pinus koraiensis Sieb. et Zucc.). The results were summarized as follows:Dead knots (unsound knots) in the pruned logs occurred more at upper parts when compared with in non-pruned ones. The numbers of knots on surface in heavily pruned trees were less than those in non-pruned trees, but there was no significant difference in moderately pruned trees. The required period to reveal clear timber surface without defects after pruning increased proportionally with the increase of knot diameter. The yield of clear lumber production increased by about 10% after 14 years from moderate pruning. The quality grade of log improved with more pruning practices. Knots appeared the most important factor in lowering the log grades.

• 한국가구학회지
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• 제21권6호
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• pp.499-504
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• 2010

한국의 전통가옥인 한옥은 대각재와 원형목으로 만든다. 이들은 열기건조하면 심각한 결함이 발생하기 때문에 보통 수개월에서 1년까지 천연건조하는데 그래도 사용중 결함이 생긴다. 열처리기술을 이용하여 이들을 $170^{\circ}C$이상에서 건조하면서 건조결함을 조사하였다. 온도곡선은 모두 하나 또는 두개의 변곡점을 나타냈다. 표면에서 37.5mm 깊이지점이 $100^{\circ}C$에 도달하는데 걸리는 시간은 열처리온도 $170^{\circ}C$ 과 $190^{\circ}C$가 두 배의 차이를 나타냈다. 열처리 후에 $148mm{\Phi}$ 원형목에 내부할렬이 많이 발생한 것이 발견되었으나, 이에 빈해 표면할렬은 거의 닫혀 있었다. 이러한 표면할렬의 변화를 $300{\times}300mm$ 대각재의 사진을 통해 관찰하였다. 중공재와 무중공재의 건조시간을 비교하였더니 두 배의 차이를 나타냈다.

• Journal of the Korean Wood Science and Technology
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• 제2권1호
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• pp.3-18
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• 1974

The exports of plywood are increasing annually and it has ranked first in the world market because of the high quality product and manufactured using mordern 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. 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 oak, ramin and meranti which are used in large quantity for manufacturing exporting wood products have been studied. The results of the research are summarized as follows. (1) The end checks and the time for drying from initial moisture content of about 40 percent to 5 percent moisture content in ovendry were investigated as follows: (2) The kiln dried results, for 30mm stock, which are presented by using kiln schedule table 3 are as follows: (3) The kiln schedules for ramin, meranti and oak are given respectively as follows: Ramin kiln schedule: Table 17 and Table 18. Meranti schedule : Table 12. Oak schedule : Table 15.

• Journal of the Korean Wood Science and Technology
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• 제21권3호
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• pp.61-66
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• 1993

24mm-thick specimens from three species of plantation-grown softwood were press dried under two platen pressures of 1.75kgf/$cm^2$ and 3.50kgf/$cm^2$ to obtain drying information regarding to drying rate, thickness shrinkage and drying defects. The influence of platen pressure on drying fare in range of moisture content (30 to 10 percent) increased for pitch pine and larch, but reduced for korean white pine at higher pressure. Thickness shrinkage was increased at the higher pressure, and estimated thickness shrinkage at final MC of 10 percent became unrealistically greater for specimens containing higher final moisture content under the great influence of compressive strain. The effects of pressure on the amount of surface checks and honeycombing were different from species used. These species should have applied lower temperature than 177$^{\circ}C$ in this study to reduce surface checks and honeycombing.

• Journal of the Korean Wood Science and Technology
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• 제13권2호
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• pp.3-13
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• 1985

본(本) 연구(硏究)는 증기전처리(蒸氣前處理)가 두께 3 cm인 상수리나무 (Quercus acutissima)의 건조속도(乾燥速度)와 건조결함(乾燥缺陷)에 미치는 영향을 알고자 하였다. 생재상태(生材狀態)의 전처리용(前處理用) 판재(板材)를 $100^{\circ}C$의 온도(溫度)에서 4시간동안 증기전처리(蒸氣前處理)한 후 무처리판재(無處理板材)와 함께 Rasmusse이 제시한 건조(乾燥)스케쥴 ($T_4-C_2$)을 사용하여 합수율(合水率) 10%까지 열기건조(熱氣乾燥)하였다. 그 결과(結果)는 다음과 같았다. 평균(平均) 건조속도(乾燥速度)는 무처리판재(無處理板材)의 경우 2.51%/일(日)이고 증기전처리판재(蒸氣前處理板材)의 경우 3.08%/일(日)였으며, 증기전처리(蒸氣前處理)로 함수율(含水率) 70%에서 10%까지의 건조시간(乾燥時間)을 약 18% 감소(減少)시켰다. 표면할열(表面割裂)에 대한 증기전처리(蒸氣前處理)의 효과(效果)는 거의 없었으나 횡단면할열(橫斷面割裂)에 있어서는 증기전처리판재(蒸氣前處理板材)가 무처리판재(無處理板材)에 비해 감소(減少)되었다. 증기전처리판재(蒸氣前處理板材)의 내부할열(內部割裂), 너비굽음 및 찌그러짐의 발생율(發生率)이 무처리판재(無處理板材)보다 약간씩 낮았다. 건조재(乾燥材)의 품등(品等)도 증기전처리판재(蒸氣前處理板材)가 무처리판재(無處理板材)보다 양호(良好)하여 1등급(等級)의 출현율(出現率)이 20% 높았으며, 2등급(等級)은 15%, 3등급(等級)은 5%씩 그 출현율(出現率)이 낮았다.

• Journal of the Korean Wood Science and Technology
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• 제31권5호
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• pp.72-79
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• 2003

신뢰성 설계에서 재료강도의 분포 특성은 기본적인 입력 변수로 사용된다. 따라서 강도특성의 분포형태 및 그에 따른 인자들을 정확하게 결정하는 것은 신뢰성 설계를 위한 필수적인 작업이다. 지금까지 강도성능 평가는 주로 무결점 소시편에 대한 실험결과가 사용되어 왔다. 그러나 이러한 방법은 부재가 실재 사용되는 조건을 제대로 반영하지 못함에 따른 오차를 포함하게 된다. 본 연구에서는 구조재로 많이 사용되는 2×6부재(38 mm×140 mm, 길이 3.0 m) 498본에 대하여 육안검사를 통해 등급을 구분하고, 휨시험을 실시하였다. 신뢰성 설계로 전환을 위해 각 등급의 강도특성에 대한 분포형태 및 인자를 결정하였다. 분포형태의 결정을 위해 정규분포, 대수정규분포, 웨이블분포의 세가지 분포형태에 대한 square error를 비교하고, KS test를 통하여 결정된 분포형태의 적합성을 확인하였다. 모든 등급에서 휨강도(MOR)의 가장 적합한 분포형태는 웨이블분포로 나타났으며, 휨탄성계수의 경우는 정규분포가 가장 적합한 것으로 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제2권2호
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• pp.22-24
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• 1974

1. 연구의 목적 및 중요성. 우리나라 합판 공업은 우수한 제조 기술을 개발하므로서 합판 수출액은 매년 증가하여 드디어 세계 제1위의 합판수출국으로 등장하게 되었으나, 합판 이외의 각종 목재가공품의 수출은 극히 부진한 실정에 있음은 주로 목재가공기술 부족에 기인하는 것으로 분석되고 있다. 따라서 본 연주에 있어서는 수출용 목재 제품의 품질을 개선하므로서 수출 증대 촉진하기 위하여 목재 가공상 가장 기초적 부문에 속하는 목재 건조법을 규명한 것이다. 2. 연구의 내용 및 범위 습재(wet wood)를 사용하면 가공후 건조 수축하여 변형하고 또는 절삭(切削), 접착 및 도장(塗裝) 등에 있어서 각종의 피해를 유발하므로 이들의 피해를 방지하기 위하여 습재를 사용전에 반드시 건조하여야 한다. 따라서 수출용재로 그 사용량이 많은 감나무, 참나무, 라왕 및 라민등에 대한 건조법 및 그 건조결함을 규명하는 동시에, 우리나라의 목재건조공업 실태도 아울러 조사하였다. 3. 연구 결과 및 활용에 대한 건의 3.1 연구 결과 3.1.1 $100^{\circ}C$ ovendry에 있어시 목구활열형성 및 함수율 5%까지 건조하는데 소요되는 시간은 표 1과 같다. 3.1.2 두께 30mm 공시목을 표 2의 건조스케줄을 적용하여 건조한 결과는 표 3과 같다. 3.1.3 감나무 건조 스케줄은, 건조 특성이 정상인 공시목에 대하여는 표4 스케줄이 적합하고 활열성이 강한 것은 상온 아래 그 관계습도를 85% 이상으로 유지하면서 서서히 기건하여 그 함수율을 25%까지 감소한 후 인공건조하는 것이 안전하다. 3.1.4 각 수종에 대하여 규면된 건조 스케줄은 다음과 같다. 라만 건조 스케줄 표 5 및 표 6 라왕(메란티) 표 7 참나무 표 8. 3.2 활용에 대한 검의 본 연구 결과는 목재가공 관계업체에 널리 보급하여, 목재건조기술 개선 특히 건조결함 방지와 건조 시간 단축에 활용되기를 바란다.

• Journal of the Korean Wood Science and Technology
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• 제2권3호
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• pp.3-16
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• 1974

One of the disadvantages of. wood and wood products is their hydroscopicity or dimensional instability. This is responsible for the loss of green volume of lumber as seasoning degrade. Dimensional stabilization is needed to substantially reduce seasoning defects and degrades and for increasing the serviceability of wood products. Recently, considerable world-wide attention has been drawn to the so-called Wood-Plastic Composites by irradiation-and heat-catalyst-polymerization methods and many research and developmental works have been reported. Wood-Plastic Composites are the new products having the superior mechanical and physical properties and the combinated characteristics of wood and plastic. The purpose of this experiment was to obtain the basic data for the improvement of wooden materials by manufacturing WPC. The species examined were Mulpurae-Namoo (Fraxinus, rhynchophylla), Sea-Namoo (Carpinus laxiflora), Cheungcheung-Namoo (Cornus controversa), Gorosae-Namoo (Acermono), Karae-Namoo(Juglans mandshurica) and Sanbud-Namoo (Prunus sargentii), used as blocks of type A ($3{\times}3{\times}40cm$) and type B ($5{\times}5{\times}60cm$), and were conditioned to about 10~11% moisture content before impregnation in materials humidity control room. Methyl methacrylate (MMA) as monomer and benzoyl peroxide (BPO) as initiator are used. The monomer containing BPO was impregnated into wood pieces in the vacuum system. After impregnation, the treated samples were polymerized with heat-catalyst methods. The immersed weights of monomer in woods are directly proportionated to the impregnation times. Monomer impregnation properties of Cheungcheung-Namoo, Mulpurae-Namoo and Seo-Namoo are relatively good, but in Karae-Namoo, it is very difficult to impregnate the monomer MMA. Fig. 3 shows the linear relation between polymer retentions in wood and polymerization times; that is, the polymer loadings are increasing with polymerization times. Furthermore species, moisture content, specific gravity and anatomical or conductible structure of wood, bulking solvents and monomers etc have effects on both of impregnation of monomer and polymer retention. Physical properties of treated materials are shown in table 3. Increasing rates of specific gravity are ranged 3 to 24% and volume swelling 3 to 10%. ASE is 20 to 46%, AE 14 to 50% and RWA 18 to 40%. Especially, the ASE in relation to absorption of liquid water increases approximately with increase of polymer content, although the bulking effect of the polymerization of monomer may also be influential. WPCs from Mulpurae-Namoo and Cheungcheung-Namoo have high dimensional stability, while its of Karae-Namoo and Seo-Namoo are-very low. Table 4 shows the mechanical properties of WPCs from 6 species. With its specific gravity and polymer loading increase, all mechanical properties are on the increase. Increasing rate of bending strength is 10 to 40%, compression strength 25 to 70%, ;impact bending absorbed energy 4 to 74% and tensile strength 18 to 56%. Mulpurae-Namoo and Cheungcheung-Namoo with high polymer content have considerable high increasing rate of strengths. But incase of Karae-Namoo with inferior monomer impregnation it is very low. Polymer retention in cell wall is 0.32 to 0.70%. Most of the polymer is accumulated in cell lumen. Effective. of polymer retention is 58.59% for Mulpurae-Namoo, 26.27% for Seo-Namoo, 47.98% for Cheungcheung-Namoo, 25.64% for Korosae-Namoo, 9.96% for Karae-Namoo and 25.84% for Sanbud-Namoo.