• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.519-532
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• 2019

The objectives of this study were to evaluate the effects of shelling ratio and resin content on the properties of bamboo oriented strand board (BOSB) from betung (Dendrocalamus asper) and to determine the correlation between the results of dynamic and static bending tests. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure and followed by washing with 1% NaOH solution. Three-layer BOSB with the core layer perpendicular to the surface was formed with shelling ratios (face:core ratio) of 30:70; 40:60; 50:50; 60:40 and binded with 7% and 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of BOSB was conducted in accordance with the JIS A 5908:2003 standard and the results were compared with CSA 0437.0 standard for commercial OSB (Grade O-1). Non-destructive testing was conducted using Metriguard Model 239A Stress Wave Timer which has a wave propagation time from 1 to $9,999{\mu}s$ and a resolution of $1{\mu}s$. BOSB with 8% resin content showed better physical and mechanical properties than those with 7% resin content. The increase of the face layer ratio improved the strength of BOSB in parallel direction to the grain. The results suggested that shelling ratio of 50:50 could be used as a simple way to reduce PF resin requirements from 8% to 7% and to meet the requirements of CSA 0437.0 standard. The results of non-destructive and destructive tests showed a strong correlation, suggesting that non-destructive test can be used to estimate the bending properties of BOSB.

• 임산에너지
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• 제18권2호
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• pp.78-83
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• 1999

본 연구에서는 소나무 소경재를 이용한 적층재의 강도 및 구조재로서의 가능성을 검토하였다. 적층재의 조합은 최외각층에 양질의 라미나를 배치하고, 저질의 라미나를 내층에 배치하여 강도 향상을 꾀하였다. 소경재로부터 제작된 적층재와 비교하기위하여 같은 단면의 소재도 휨강도 실험을 실시하였다. 적층재에 사용된 라미나의 영계수를 이용한 적층재의 영계수 추정은 실측치가 추정치보다 약간 높은 경향을 보였다. 제작된 적층재의 휨강도는 673 kgf/㎠, 영계수 98,200 kgf/㎠였다. 저질 소경재의 라미나의 적절한 조합에 의해 적층재는 같은 단면의 소재에 버금가는 강도를 나타냈다.

• Journal of the Korean Wood Science and Technology
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• 제12권3호
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• pp.15-24
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• 1984

The $3{\times}3{\times}30\;cm^3$ sized specimens of Douglas-fir(Pseudotsuga menziesii) and western hemlock(Tsuga heterophylla) in this study were soaked in four fire-retardant solutions of ammonium sulfate, monoammonium phosphate, diammonium phosphate, and aluminium chloride for 1, 24, 72, 168, and 336 hours. Subsequently they were air-dried and burned at high temperature of ca. $1,800^{\circ}C$ and for short time of 5 minutes. This study estimated the relationship between the adsorbed chemicals and the residual weight ratio or residual bending strength of these partly burned lumbers. The results were as follows; 1) In average amount of chemical adsorption, diammonium phosphate showed the largest and aluminium chloride the smallest regardless of species but monoammonium phosphate was larger in Douglas-fir than that of western hemlock. 2) The amount of chemical adsorption was larger in western hemlock than Douglas-fir on the whole. 3) The amount of chemical adsorption was increased with the increase of soaking time but the rate of increase began to decrease at 200hrs. 4) Residual weight ratios showed no difference between species but showed differences among the chemicals treated i.e. monoammonium phosphate, diammonium phosphate, ammonium sulfate and aluminium chloride in turn from the largest to the smallest. 5) MOR values showed linear increase with the increase of residual weight ratios but showed no difference in species and chemicals respectively. 6) In the relationship between amount of chemical adsorption and MOR, only diammonium phosphate showed the curve of secondary degree with significance in Douglas-fir. 7) The MOE value of burned Douglas-fir lumber increased and showed significance of 99% as the adsorbed chemical amount increased, but among the chemicals only monoammonium phosphate showed significance. The MOE value of burned western hemlock lumber didn't show significance. 8) In only Douglas-fir, the correlation between adsorbed chemical amount and work to proportional limit showed significance in only monoammonium phosphate. And in both Douglas-fir and western hemlock, the correlation between adsorbed chemicals and work to maximum load showed significance in monoammonium phosphate.

• Journal of the Korean Wood Science and Technology
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• 제44권5호
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• pp.664-676
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• 2016

최근 여러 사회적인 변화에 따라 한옥에 대한 수요가 증가하고 있다. 하지만 한옥은 수가공으로 인한 가격 상승의 큰 문제점을 가지고 있다. 따라서 한옥 접합부의 모듈화를 위해 기계가공과 수가공과의 성능비교를 하였다. 더글라스퍼를 이용하여 두 가공법으로 실대재 주먹장을 제작하였다. 두 가공법에 대해 휨 성능을 평가하였다. 평균 최대하중은 같은 치수의 그룹을 비교했을 때 기계가공이 수가공에 비해 약 1.5배 더 높았다. 유의성 검증결과 두 가공법 모두 각 요소의 크기변화는 강도에 큰 영향을 미치는 것으로 나타났다. 다중회귀분석을 통해 목길이와 목두께는 최대하중과 비례 관계였으나 목너비는 반비례관계인 것을 알 수 있었다. 본 연구는 한옥 접합부를 모듈화 함에 있어 기초자료로 사용할 수 있을 것이다.

• Journal of the Korean Wood Science and Technology
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• 제45권3호
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• pp.360-367
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• 2017

본 연구에서는 단열성능 및 물리적 성질이 우수한 친환경 목섬유 단열재의 제조 기술을 확립하기 위하여 멜라민 요소 폼알데하이드(MUF), 페놀 폼알데하이드(PF), emulsified MDI (eMDI) 및 라텍스계 수지 등 서로 다른 접착제로 제조한 저밀도섬유판의 특성을 비교하였다. 그 결과 MUF, PF, eMDI 수지 접착제로부터는 경질(硬質) 저밀도섬유판이, 라텍스계 수지 접착제로부터는 연질(軟質)의 저밀도섬유판이 각각 제조되었다. 모든 저밀도섬유판은 일반 중밀도섬유판에 비해 현저히 낮은 열전도율을 나타냈으며, 압출 발포 폴리스티렌과 유사한 단열 성능을 나타내는 것으로 조사되었다. 한편 본 연구에서 제조한 저밀도섬유판 중 eMDI를 사용한 것은 흡수 두께/길이 팽창률 및 휨 강도 등 물리적 성질이 가장 우수하였다.

• Journal of the Korean Wood Science and Technology
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• 제19권3호
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• pp.62-71
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• 1991

An evaluation of bending test of composite I and Box beams for determining the ultimate strength limit design criteria was presented. Maxium loads of composite I beams were found in beams composed of thicker upper flanges and/or vertical LVL flanges. These loads of plywood web beams were greater than those of PB web beams. Maximum loads of unsymmetrical box beams were less than those of symmetrical box beams. Thus, it took on different phase in box type beams. Ultimate loads of composite beams were greater than those of solid. The failure of composite beams were abrupt and failure mode was classified into following categories; Edgewise shear failure in web, delamination in flange-web joint, tension failure and tearing in LVL flanges, and web delamination. These failures of composite beams were appeared at the mixed mode. The influence factor affecting the performance of tested composite beams was shear strength of PB-web composite beams and compressive strength in plywood-web composite beams. It was also assumed that the influence factors on structural performance on composite beams were flange quality, web material and geometry of cross section. As one of the design methods resisting to compressive stress that was required in the case of small span to depth ratio and deep beams. composite I-beams composed of thicker upper flanges comparing to lower flanges were very effective in structural performance.

• Journal of the Korean Wood Science and Technology
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• 제33권3호통권131호
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• pp.30-37
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• 2005

톱밥과 왕겨를 혼합하여 보드를 제조한 후 페놀수지에 함침율 40~70%로 함침한 후 소성온도 $600{\sim}1200^{\circ}C$에서 소성하여 혼합세라믹을 제조한 다음 수지함침율과 소성온도에 따른 혼합세라믹의 밀도변화, 중량 및 치수감소율과 휨강도를 조사하였다. 수지함침율이 증가함에 따라 소성 후 두께 및 중량 감소율은 감소하였고 밀도와 휨강도는 증가하였다. 소성온도가 증가함에 따라 소성 후 길이, 두께 및 중량 감소율은 증가하였고 밀도는 소성온도 $800^{\circ}C$까지는 증가하다가 $1200^{\circ}C$ 에서는 약간 감소하였다.

• Journal of the Korean Wood Science and Technology
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• 제35권5호
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• pp.7-15
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• 2007

To evaluate the durability of finger-jointed woods according to change of humidity conditions, four types of finger-jointed woods glued with different kinds of adhesives and finger pitches were made with Sitka spruce, and the effect of humidity conditions on creep performances was investigated. The shape of creep curves differed among humidity conditions, and the inclination of creep curves was greatest in 85%RH, and lowest in 65%RH. Their creep curves showed a linear behavior beyond approximately one hour, regardless of humidity conditions. The A values of the creep curves fitted to power law increased with increasing relative humidity, whereas the A' values were in order of 30 > 85 > 65%RH unlike the A values. The initial deformation increased with increasing relative humidity, whereas the creep deformation unlike the initial deformation was in order of 85 > 30 > 65%RH, and it was found that the creep deformation of finger-jointed woods indicated the smaller amount in air-dry moisture content rather than in a low moisture content less than 30%RH. Finger-jointed woods with 6.8 mm (L) pitch had the greater creep amount than in those with 4.4 mm (S) pitch in all humidity conditions. The difference of creep amount between both adhesives in all humidity conditions was small. Relative creep at 240 hr was greatest as 62.2~71.9% in 85%RH, and the values indicated 2.1~2.6 times that of 30%RH and 3.0~3.6 times that of 65%RH and were equal or slightly greater than that of solid spruce.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.872-882
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• 2017

The objective of this study was to evaluate the properties of bamboo oriented strand board (B-OSB) from andong (Gigantochloa psedoarundinacea) and betung (Dendrocalamus asper) with and without steam treatment. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure. The extractive content of bamboo strands before and after steam treatment were determined according to a standard (TAPPI T 204 om-88). Three-layer B-OSB with the core layer perpendicular to the surface and back layers were formed and binded with 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of the boards were conducted in accordance with the JIS A 5908:2003 standard. The results showed that steam treatment of bamboo strands significantly reduced the extractive content. Steam treatment tended to increase the dimensional stability and mechanical properties of B-OSB from andong and betung. The results showed that the dimensional stability and bending strength of B-OSB from betung was higher than those of andong. The internal bond strength of B-OSB from andong was higher than betung owing to a greater amount of extractives dissolved during the steam treatment.

• Journal of the Korean Wood Science and Technology
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• 제31권1호
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• pp.52-60
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• 2003

액체암모니아 처리 침·활엽수 소시편의 물리적 성질을 무처리와 비교하였다. 처리시간은 4와 8시간으로 하였다. 동일한 환경에서 처리재의 평형함수율은 무처리재보다 항상 높았으나 전건 후에는 차이를 나타내지 않았다. 암모니아 처리를 오래할수록 방사방향과 접선방향으로 수축이 일어났으나 섬유방향에는 변화가 없었다. 또 처리시간이 길수록 초음파 전달속도는 감소하고 밀도는 증가하였다. 따라서 동탄성계수는 감소함을 보였다. 밤나무의 가소화는 증기처리가 액체 암모니아 처리보다 효과 있음과 인사이징이 침·활엽수 모두 액체 암모니아 침투성을 높이지 못했음이 밝혀졌다. 액체 암모니아 처리는 5mm두께 침엽수 시편에서 제일 좋은 가소화 효과를 보였다. 상대유전율과 열전달계수도 측정하여 처리재와 무처리재를 비교하였다.