• Journal of the Korean Wood Science and Technology
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• 제38권3호
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• pp.178-184
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• 2010

인피섬유로 한지를 제조하고 남은 닥나무 목질부를 고부가가치화 하기 위하여 닥나무 목질부로 파티클 보드를 제조하고 페놀수지 함침율 변화에 따른 닥나무재료 우드세라믹을 제조하여 물성을 검토하였다. 밀도, 휨강도성능, Brinell 경도, 압축강도 등은 수지함침량이 증가할수록 증가하였으며 밀도와 휨강도성능, 경도, 압축강도간 및 휨탄성계수와 강도간에는 유의성이 인정되는 밀접한 상관관계를 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제50권4호
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• pp.237-245
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• 2022

This study examined the structural performance of experimental parallel strand lumber (PSL) from a Larch veneer strand. The prototype of PSL from a Larch veneer strand was manufactured in the experimental laboratory and tested. The bending and dowel bearing strength were determined from the modulus of elasticity (MOE), modulus of rupture (MOR), and dowel bearing strength based on a 5% offset yield load. The test results indicated that the average MOR of PSL was higher than that of 2 × 4 dimension lumber, and the average MOE of PSL was lower than that of 2 × 4 dimension lumber. A linear relationship was observed between the MOR and MOE. The allowable bending stress of PSL was derived as specified in ASTM D2915 and compared with other research. The dowel bearing strength of PSL in parallel to the grain was approximately double that perpendicular to the grain of PSL. A comparison of several theoretical calculations based on each national code for the dowel bearing strength was conducted, and some theoretical equations produced results closer to the experimental results when it was parallel to the grain, but the difference was higher in the case perpendicular to the grain. The test results showed that PSL made with Japanese larch veneer strands appeared to be suitable for a raw material of structural composite lumber (SCL) appeared to be used as a raw material for SCL.

• Journal of the Korean Wood Science and Technology
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• 제52권4호
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• pp.383-392
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• 2024

Laminated bamboo is an engineered bamboo technology to maintain its mechanical durability for both construction and furniture materials. This study was conducted to assess the properties of laminated bamboo made from Betung bamboo at different culm positions and laminate orientations. The materials used in this study were 4-year Betung bamboo (Dendrocalamus asper) obtained from a community forest in Yogyakarta and polyvinyl acetate resin as adhesive. Two factors were applied for this study, i.e., culm position (lower, middle, and upper) and laminate orientations (vertical and horizontal direction). To examine the mechanical properties, a static bending test and the hardness test were performed in accordance with ASTM D1037-99. Moisture content and density were determined in accordance with BS 373-1957. The results indicated that there was no interaction between the culm position and laminate orientation on the moisture content, density, static bending properties and hardness. The culm position affected the static bending and hardness, with the higher position of the culm resulting a greater strength. The laminate orientation also affected the strength of laminated bamboo, with the vertical direction resulting in higher strength than the horizontal.

• 한국가구학회지
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• 제10권1호
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• pp.65-71
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• 1999

The bending performance of sloped finger-jointed Rhus verniciflua were tested in order to improve the strength properties of finger-joint. Sloped finger-cut pieces were jointed with three kinds of adhesives (polyvinyl acetate, polyvinyl-acryl acetate and oilic resin). The slope ratios of finger joints were 0, 1.0, 1.5, and 2.0. The MOE, MOR and deflection to maximum load in bending of sloped finger-joints and solid wood specimen were measured. The results were : 1) The efficiencies of MOE to finger and sloped finger-joints to the solid wood were almost same in the three kinds of adhesives(polyvinyl acetate, polyvinyl-acryl acetate and oilic urethane resin) and there were some effect of slope on the MOE in a sloped finger-joint for three kinds of resin adhesives. 2) There was the effect of slope on the MOR in sloped finger-joints in every kind of adhesive. The efficiencies of MOR in slope ratios of 0 and 2.0 ranged 65-79%, respectively. There was also a slight effect of the kinds of adhesives on the MOR. However, the efficiencies of deflection to the urethane resin adhesive were much less than those of polyvinyl acetate, polyvinyl-acryl acetate resin adhesives except the slope ratio of 0. 3) It might be impossible to estimate the bending stregth of sloped finger-jointed Rhus verniciflua by using MOE. The correlation coefficient(0.192) between MOE was very low and not significant at 5% level.

• 한국가구학회지
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• 제12권2호
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• pp.1-10
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• 2001

As finger joint method has a high rate of yield and high strength and ease in working, it has been widely used as an end joint method for solid wood and wood based-material. Therefore, we end-joined the material of Pinus densiflora, Quercus variabilis and populus euramericana with polyvinyl acetate adhesive and resorcinol phenol resin adhesive. The effect of difference (0, 0.15, 0.3, 0.45mm) between the dimensions of tip width and root width of the finger (DTRW) on bending strength properties was as follows: 1. In the case of polyvinyl acetate adhesive, DTRW had no effect on bending modulus of elasticity(MOE) and modulus of rupture(MOR) of the three kinds of species, because their bonding layers were destroyed by slippage, not their woody parts. 2. In the case of resorcinol phenol resin adhesive, the material of Quercus variabilis showed an optimal result at 0.15 or 0.3 of DTRW, while the poplar did at 0 of DTRW 3. The differences in efficiency ratio of bending MOR of populus euramericana, Pinus densiflora and Quercus variabilis species according to the kind of adhesive were 13-29%, 23-30% and 45-53%, respectively.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.32-36
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• 1995

A study was conducted to evaluate the dynamic mechanical properties (modulus of elasticity, resonant frequency and interanal friction) of compression wood in Pinus densiflora. Vibration method was used for estimation of dynamic modulus of elasticity and the values were compared to those of static bending modulus of elasticity. The results obtained are as follows: 1. The dynamic modulus of elasticity of compression wood decreased, whereas that of normal wood increased, with increasing specific gravity. 2. The resonant frequency of compression wood decreased, whereas that of normal wood increased, with increasing specific gravity. 3. The internal friction of compression wood increased with increasing specific gravity. 4. The correlation coefficients between dynamic and static moduli of elasticity in compression and normal woods were high.

• Journal of the Korean Wood Science and Technology
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• 제35권5호
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• pp.38-45
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• 2007

Flakeboards made from ring- and drum-cut flakes of Douglas-fir, hemlock, red lauan and kapur using two kinds of resin levels were evaluated for the selected properties according to flake thickness. The pH and buffering capacity of four species were determined. Those of kapur were extremely different from the other three species. These pH and buffering capacity values result in the poor internal bond strength of kapur flakeboard. The internal bond strength was affected significantly by flake thickness, resin content and species. MOR and MOE in bending strength were maximized at medium drum-cut flake thickness. Screw holding strength was not consistent for flake thickness, but it was influenced by species. Thickness swelling and water absorption of Douglas-fir and hemlock flakeboard were minimized at medium drum-cut flake thickness.

• Journal of the Korean Wood Science and Technology
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• 제44권1호
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• pp.57-66
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• 2016

이 연구에서는 환경부하가 적은 산림훼손지 생태복원재료의 개발을 목적으로, 콘크리트와 국내산 침엽수 4종, 국내산 활엽수 3종의 제재라미나를 복합적층하여, 휨 크리프 성능에 미치는 수종의 밀도의 영향을 조사하였다. 목재-콘크리트 복합적층재의 휨 크리프곡선은 수종에 관계없이 시간에 따라 크리프곡선의 우측상변이 현저히 증가하는 형태를 나타내었고, 하중부하 후 약 30분 - 1시간 이후에서는 목재 및 목질재료와 같이 거의 직선적인 거동을 나타내는 것이 확인되었다. 목재-콘크리트 복합적층재의 초기변형은 수종의 밀도의 증가에 비례하여 변형이 감소하였고, 이 값은 콘크리트의 0.9 - 1.2배의 값을 나타내었다. 목재-콘크리트 복합적층재의 크리프변형은 콘크리트의 0.4 - 0.8배의 낮은 값을 나타내어 복합적층에 의한 콘크리트의 크리프변형의 현저한 감소가 확인되었다. 목재-콘크리트 복합적층재의 상대 크리프는 8.2 - 17.0%의 범위로 복합적층에 의해 콘크리트의 그것보다 0.3 - 0.7배의 매우 낮은 값을 나타내는 것이 확인되었다. 이 결과는 목재와 콘크리트의 복합적층에 의해 기존 콘크리트재료의 크리프변형을 감소시킨 산림훼손지 생태복원재료로 응용가능성을 나타낸다.

• Journal of the Korean Wood Science and Technology
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• 제42권4호
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• pp.385-392
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• 2014

우리나라의 중요한 조림 수종 중에서 낙엽송을 대상으로 하여, 간벌실시에 따른 물리 역학적 성질을 비교 평가함으로써 간벌 실시가 목재의 재질에 미치는 영향과 양질재 생산 및 목재의 효율적 이용을 위한 연구결과는 다음과 같다. 간벌정도에 따른 시료는 무간벌, 약도간벌, 강도간벌을 실시한 광릉시험림에서 벌채하여 사용하였다. 간벌 정도에 따른 평균 만재율은 무간벌 < 약도간벌 < 강도간벌의 경향이었고 평균 연륜폭은 무간벌 < 약도간벌 또는 강도간벌의 경향이었다. 간벌 정도에 따른 평균 휨강도는 무간벌 > 약도간벌 >강도간벌의 경향이었고 간벌 정도에 따른 평균 압축강도는 무간벌 > 약도간벌 >강도간벌의 경향이었다. 이러한 결과로 낙엽송은 간벌에 의하여 휨 및 종압축강도가 감소하는 경향이었다.

• Journal of the Korean Wood Science and Technology
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• 제12권2호
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• pp.10-19
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• 1984

The $3{\times}3{\times}30$ ($cm^3$) sized lumbers of Populus alba-grandulosa L. were treated with four fire-retardant solutions of ammonium sulfate, monoammonium phosphate, diammonium phosphate and aluminium chloride for 1, 15, 30, and 60 minutes and 1, 3, and 7 days. Thereafter they were air-dried and burned at high temperature about $1,800^{\circ}C$ and for short time of five minutes. This study estimated the relationship between absorbed chemical amounts and rate of weight loss or residual bending strength of these burned lumbers. The results were as follows: 1) In absorption amount of fire-retardant chemicals, diammonium phosphate showed the largest, aluminium chloride the smallest, but monoammonium phosphate and ammonium sulfate showed similar level. 2) The absorption amount of chemicals was decreased with the increase of specific gravity in the same species except aluminium chloride. 3) The rate of weight loss was decreased as the absorption amount of chemicals increased, especially monoammonium phosphate was most effective. 4) The MOR value of the residual bending strength was increased as the absorption amount of chemicals increased and especially monoammonium phosphate showed the most efficient effect. 5) Aluminium chloride showed more striking increase of MOR value of residual bending strength with the increase of absorption amount than any other chemical, therefore its MOR value was similar to the maximum MOR value of the most effective monoammonium phosphate. 6) The correlation between weight loss and MOR value of the residual bending strength was negative and aluminium chloride showed the most striking negative relation, but the others showed similar trends. 7) The correlation between work to proportional limit and absorption amount of chemicals was positive and the degree of increase in work to proportional limit was most in aluminium chloride, and the next, in monoammonium phosphate and diammonium phosphate in turn. 8) The correlation between work to maximum load and absorption amount of chemicals showed positive and diammonium phosphate revealed the best result and aluminium chloride showed better results than other two chemicals.