• Journal of the Korean Wood Science and Technology
• /
• 제27권4호
• /
• pp.38-42
• /
• 1999

Average moisture content of 30mm-thick Korean red pine(Pinus densiflora) was estimated nondestructively and continuously using surface temperature rise by radiation heating and moisture gradient profile in wood. The surface temperature rises increased as surface moisture contents decreased and good relationships were found between surface moisture contents and surface temperature rises at three different feed speeds of 10, 20 and 30 m/min. Average moisture content could be described as a function of surface moisture content and wood thickness.

• Journal of the Korean Wood Science and Technology
• /
• 제30권3호
• /
• pp.104-108
• /
• 2002

Nail withdrawal tests were conducted on clear wood of domestic small diameter logs. Nails were driven into the cross and longitudinal sections of each specimen, then nail withdrawal tests were performed. Nail withdrawal loads are strongly dependent on the direction of nail positions. The average load values for the nail withdrawal both in cross section and longitudinal section are higher in high specific gravity (SG) wood of sawtooth oak (Quercus acutissima Carr.) than those in low SG wood of Korean red pine (Pinus densiflora Sieb. et Zucc.) and pitch pine (Pinus rigida Mill.). The average ratio of the nail withdrawal loads for side-grain and end-grain are higher in the low SG wood than that in the high SG of wood. Both linear and non-linear regression analyses were conducted on nail withdrawal load with SG, good correlations were obtained between nail withdrawal load and SG.

• Journal of the Korean Wood Science and Technology
• /
• 제34권3호
• /
• pp.15-21
• /
• 2006

목질펠릿을 탄화하여 탄화물의 이용가능성을 알아보기 위하여 밀도, 수율, 원소조성, 발열량, 메틸렌블루흡착량 등의 특성을 분석하였다. 목질펠릿은 현사시, 일본잎갈나무, 잣나무, 소나무, 졸참나무의 수피를 포함한 톱밥을 이용하여 제조하였다. 목질펠릿으로부터 $0.5{\sim}0.7g/cm^3$의 고밀도 탄화물을 얻을 수 있었으며, 탄화온도가 증가하면 탄화물의 탄소함량과 발열량이 증가하였다. 목질펠릿으로부터 얻어진 탄화물의 메틸렌블루 흡착 특성은 목재의 것과 거의 유사하였다.

• Journal of the Korean Wood Science and Technology
• /
• 제33권1호통권129호
• /
• pp.17-20
• /
• 2005

원적외선의 상업적 이용을 위한 가열분야의 연구자들이 재료간의 비교 관능치로 상온에서 측정불가능했던 80년대에 발표한 일반 목재의 원적외선 방사율에 관한 데이터는 구체적으로 어떤 수종이 어떤 온도에서 어떤 방법으로 측정하였는지에 대한 정확한 근거가 없다. 따라서 목재의 장점으로 주거환경에 사용되는 목재의 원적외선 방사에 관한 성질을 상온에서 측정하여 인체친화적 자료를 구체적으로 구하였다. 한국산 5개 수종의 $5{\sim}20{\mu}m$ 범위에서의 측정된 원적외선 방사율은 $40^{\circ}C$에서 90~91%를 나타내어 우수한 원적외선 물질임이 밝혀졌고 침 활엽수재 간이나 산공재와 환공재, 또한 밀도가 높은 수종이나 낮은 수종 간에도 원적외선 방사율과 방사에너지의 차이가 전혀 없었다.

• Journal of the Korean Wood Science and Technology
• /
• 제33권5호통권133호
• /
• pp.13-20
• /
• 2005

This paper deals with flexural vibration techniques as a means of predicting bending strength properties for quarter-sawn and flat-sawn planes of red pine containing knots. Dynamic modulus of elasticity $(MOE_d)$ was calculated from resonance frequency obtained from the flexural vibration induced by a magnetic driver in quarter-sawn and flat-sawn planes of red pine containing knots. The dynamic MOE were well correlated to bending strength properties. Their correlation coefficients ranged from 0.866 to 0.800 for the regression between dynamic MOE and static bending MOE or MOR. The difference of the values between quarter-sawn and flat-sawn was very small. These values were higher than correlation between percentage of total knot diameter to total width of red pine specimen $(K_T(%))$ as well as $K_O(%)$ base upon ASTM D 3737 and static bending strength properties (correlation coefficient r = 0.448~0.704), and were similar to those between static bending MOE and bending MOR (r = 0.850). These results indicate that dynamic MOE obtained from resonance frequency induced by flexural vibration of magnetic driver is able to effectively use for predicting of static bending strength of red pine containing knots as well as static MOE.

• Journal of the Korean Wood Science and Technology
• /
• 제39권6호
• /
• pp.481-489
• /
• 2011

본 연구에서는 소나무와 낙엽송 스킨팀버의 ACQ-2, CUAZ-2, CuHDO-1 가압처리 특성을 평가하기 위해 소나무 변재부와 낙엽송 심재부 시험편을 대상으로 처리용 목재의 함수율이 방부제 처리도에 미치는 영향과 방부제 유효성분인 구리의 처리목재 내 정착 특성을 조사하였다. 본 연구 결과에 의하면 소나무 변재부는 방부제 종류에 관계없이 함수율 30%부터 사용환경 범주 H3용 처리목재의 침윤도와 흡수량 기준을 모두 만족하였다. 완벽한 방부제 침투가 가능한 소나무 변재부에서 깊이에 따른 방부제 흡수량 경사를 조사한 결과, 방부제 종류에 따른 차이가 관찰되었다. CuHDO-1 처리 시험편에서 발생한 경사가 ACQ-2와 CUAZ-2 처리 시험편에서의 경사보다 심했는데, 특히 고함수율(25, 30%) 시험편에서 경사가 저함수율(15, 20%) 시험편에서보다 심함을 알 수 있었다. 그러나 난주입성인 낙엽송 심재부는 처리용 목재의 함수율 조건 및 방부제 종류에 관계없이 처리도 가 매우 불량하였다. 낙엽송 심재부의 처리도 개선을 위해 증기 전처리($121^{\circ}C$의 포화수증기 조건에서 12시간 처리)를 실시한 결과, 낙엽송 심재부의 침윤도와 흡수량 모두 사용환경 범주 H3용 처리목재 기준에 부합하게 처리도가 개선됨을 확인할 수 있었다. 소나무 변재부와 낙엽송 심재부 시험편에서 공히 방부제 유효성분인 구리의 정착이 비건조 양생에 비하여 건조 양생에서 빨리 진행되었다. 소나무 변재부는 양생 초기 3~6일, 낙엽송 심재부는 양생 1일 이내에 3주간 정착된 구리 양의 95% 이상이 정착되었다. 양생 3주 후 처리목재 내에 미정착 상태로 남아있는 구리의 양은 ACQ-2, CuHDO-1, CUAZ-2 순으로 많았는데, 이는 처리용 작업액에 존재하는 구리의 양과 비례하였다.

• Journal of the Korean Wood Science and Technology
• /
• 제37권5호
• /
• pp.465-473
• /
• 2009

Three failure theories were studied to evaluate the wood strength variation with grain slope. Maximum stress theory, Tsai-Hill theory and Hankinson formula were presented to hypothesize the failure of wood according to grain slope to loading direction. Red pine and Japanese larch were used as materials to simulate failure strength prediction with grain slope. Calculation of strength results was that the strength of wood drops rapidly between parallel to grain orientation (0 degree) and 15 degree grain orientation. The strength of wood with grain orientation were somewhat different at small grain angles among failure theories, and this tendency was due to tension and compression distinction, and shear accounting in each theories. For the above 45 degree grain orientation, the predicted failure strength of wood with grain variation were very close in each failure theories and were useful in assessing failure strength of wood. The applicable these theories should be considered that the wood has different behavior in tension and compression, and this lead to different strength at small grain angles in each theories. Furthermore, reconsideration is needed to assess the failure strength of wood at small grain angles in Hankinson formula and further studies are necessary to accounting for shear behavior at small grain angles.

• Journal of the Korean Wood Science and Technology
• /
• 제21권1호
• /
• pp.39-50
• /
• 1993

The purpose of this study was to describe the micromorphological changes in Korean red pine (Pinus densiflora S. et Z.) wood decayed by a major brown-rot fungus, Lentinus lepideus, using scanning electron microscope and transmission electron microscope. At the end of the 12-week exposure to the fungus in soil block procedure(ASTM 1971), test blocks sustained 5.02% weight loss. The formation of bore hole by hyphae and penetration of hyphae through bordered pit were not observed. Instead, fungal hyphae appeared to penetrate axially tracheid luminar from the the ray cells via cross field pits. Hyphae were mainly found in lignin rich cell corner regions of tracheids, and also extensive degradation of tracheid wall occurred in this region. Extensive degradation of $S_2$ layer occurred without noticeable alteration of the $S_3$ layer, but warty layer and compound middle lamella remained relatively intact. Localized erosion, the characteristic of white rot, was observed in some cell wall and wall components including lignin were found to be decomposed.

• Journal of the Korean Wood Science and Technology
• /
• 제14권2호
• /
• pp.36-42
• /
• 1986

Both the control and heated specimen of oak, hornbean, alder, poplar, red pine and pitch pine among domestic commercial species and taun imported were used for radial and tangential shrinkage and movement that occurred on changing the relative humidity of the atmosphere from 90 percent to 60 percent at $25^{\circ}C$. The results of this study were as follows. 1. The radial and tangential shrinkage of the control and heated hornbean and oak wood, except alder, of high specific gravity showed greater than species with low specific gravity. The ratio of tangential to radial shrinkage was 1.46 for taun to 2.70 for alder. Green volume specific gravity of the heated and soaked specimen of all species except poplar decreased 1.5 to 3.1 percent. Shrinkage of the heated specimen increased more than that of the control specimen, and antishrink efficiency of all timbers except alder had negative value. Shrinkage from green to air dry of treated specimens increased more than case of total shrinkage, and radial shrinkage of those specimen increased greater than tangential shrinkage. 3. The movement of the heating specimen for 120 hours decreased than those of the control and the heating specimen for 240 hours. The movement of heating oak, poplar, red pine and pitch pine (or 240 hours increased rather than those of the control specimen.

• Journal of the Korean Wood Science and Technology
• /
• 제9권3호
• /
• pp.24-30
• /
• 1981

This experiment was carried out to determine the drying time from green to oven dry and estimate the moisture content of wood, such as red lauan (Shorea Spp.), Douglas fir (Pseudotsuga menziesii), Birch (Betula platyphylla), and oak (Quercus aliena), at various thickness, paralleled to fiber, of specimen for M.C. by oven dry method (100-105$^{\circ}C$). The results obtained are summarized as follows: 1. The drying time from green to oven dry decreases as the thickness of specimen for M.C. becomes to be thined, and that time at 10mm thickness are 14 hrs, for birch wood and 24 hrs, for oak wood. 2. The relative formulae between thickness (X) of specimen for M.C. and drying lime (Y) from 12% to oven dry are showed in Fig. 3. 3. The M.C. based on the weight of specimen for M.C. at t% can be obtained from the formula (2), and the drying time to 1% are shorter than that time to oven dry by approximately three times.