• Journal of the Korean Wood Science and Technology
• /
• 제42권4호
• /
• pp.477-482
• /
• 2014

최근 목재이용에 대한 소비자의 요구가 다양화 되면서 목조 주택뿐만 아니라 공공건물 및 놀이시설 등에 고내구성 집성재에 대한 시장수요가 증가할 것으로 예상된다. 본 연구는 국산 낙엽송으로 제조한 구조용 집성재에 적합한 난연처리 기술개발 및 기준을 정립하기 위한 목적으로 수행되었다. 난연처리된 국산 낙엽송 제재목을 이용하여 구조용 집성재를 제조하고 제조 후 집성재에 미치는 영향을 조사하였다. 낙엽송 난연처리재의 경우 구조용 집성재의 강도조건에는 만족하였으나 난연제 처리에 의한 강도적인 감소와 박리 발생 등은 개선될 필요가 있었다. 집성재의 제조 후 주입식 난연처리 혹은 도포식 난연처리 기술 개발이 요구되었다.

• 한국토양비료학회지
• /
• 제32권2호
• /
• pp.115-122
• /
• 1999

본 연구는 인공조림된 잣나무임분과 일본잎갈나무임분을 대상으로 1997년 6월에 요소 (N: $150kg\;ha^{-1}$)를 시용하고 1년간의 토양 및 토양수중 양분함량 변화를 조사하였다. 토양 pH는 시용 후 잣나무임분에서는 급격한 감소경향을, 일본잎갈나무임분에서는 완만한 증가경향을 보였으나 시간이 경과함에 따라 시용 전 농도수준으로 회복되고 있었으며, 전탄소, 전질소는 시용 후 증가 경향을 보이다. 일정한 값을 나타내고 있었다. 치환성 Ca, Mg는 시용 후 감소하는 경향을 보였으나 치환성 K는 증가하는 경향을 보였다. 일본잎갈나무의 토양수의 pH를 제외하고는 양임분 모두 토양수의 pH와 시용 후 감소하는 양이온중 Ca, $NH_4-N$, 음이온중 $NO_3-N$, $SO_4-S$, Cl 농도는 초기간계에서 증가하였으나, K, Mg, 농도는 시용 후 1~2개월 후부터 증가하기 시작하여 4개월 후에 최고 농도치를 나타내고 있었다. 시용 후 급격히 증가한 토양수중 각 용존원소 농도가시용 전과 같은 수준의 농도로 회복되는데에는 Ca, $NH_4-N$, $SO_4-S$, Cl에서 약 1개월, $NO_3-N$, K, Mg에서는 6~12개월로 용존원소에 따라 그 경향을 달리하고 있다.

• Journal of the Korean Wood Science and Technology
• /
• 제36권6호
• /
• pp.88-95
• /
• 2008

내구성과 관련하여 구조부재의 수축문제가 목구조에서는 커다란 관심사가 되고 있다. 특히, 목재 소재를 적극 활용하는 전통공법에서는 짜맞춤 부위, 부재와 벽 등에서 발생하는 건조수축에 의한 갈라짐 등의 결함이 더욱 문제시되고 있다. 또한, 최근 기둥-보 공법에서 많이 사용되고 있는 국내산 낙엽송 집성재의 이용에 있어서도 함수율변화로 인한 수축과 팽윤에 대한 검토를 행할 필요성이 제기되고 있다. 낙엽송 소재와 접착층수를 달리한 낙엽송 집성재의 시험편에 대해 다양한 함수율상태에서의 치수변화율을 살펴보았다. 건조수축에 의한 치수변화 억제효과는 3층 이상의 접착층을 가지는 시험편에서 그 효과가 현저함을 알 수 있었다. 그리하여, 소재를 사용할 경우 최종사용조건에 맞추어 건조를 충분히 행하거나, 구조부재로 집성재를 이용함으로써 건조수축 문제를 어느 정도 해결할 수 있는 것으로 판명되었다.

• Journal of the Korean Wood Science and Technology
• /
• 제18권3호
• /
• pp.42-52
• /
• 1990

In this study, thick 24mm glulams were composed of thick. 3, 4, 6, 8mm Larch laminas to study that the theoretical analysis and the experimental analysis regarding the location of neutral axis of the glulams were compared, and to study on the effect of location of neutral axis on mechanical properties of glulam. The variation of location of neutral axis after proportional limit(or elastical limit) was studied to offer basic data to make the better composition method of glulam. The result obtained can be summarized as follows: 1. The theoretical neutral axis was 0.547 in solid wood, and also 0.547 in glulams because glulams were composed of only Larch laminas. 2. In solid wood, the deviation of the theoretical and the experimental neutral axis location was 0.1%, But in glulams, the deviation from-12.2% to + 7.8% showed nonuniform pattern but no large deviation. Because laminas was only of Larch and so the mechanical properties of laminas were monotonous. 3. The neutral axis exerted no influance on the elasticity of glulam, which meaned that the maximum shear strength in the neutral axis showed no influance on elasticity limit. 4. The only minutely lower elasticities of glulam than that of solid wood were shown. This was because of influance of glue lines of glulam on the elasticlties. 5. The failure type of glulam was wholly simple tension failure and the horizontal shear failure near neutral axis was not taken place, which was that glue line was complete in bonding and the strength of the lamina was not various but uniform. 6. The ratio of tension strain($^{\varepsilon}t$) I compression strain($^{\varepsilon}c$) initially showed uniform level After the elasticity limit. the ratio was increased with the flow of time and so the tension strain was more increased than compression strain. So this proved tension lamination technique, which is that the mechanical properties of glulam could be improved, if the lamina of more superior strength would he added on the bottom side of the glulam.

• Journal of the Korean Wood Science and Technology
• /
• 제46권1호
• /
• pp.93-99
• /
• 2018

국내산 낙엽송 소경각재의 휨 강도 성능을 예측하기 위하여 비파괴적인 지표의 검토가 필요하다. 본 연구에서는 낙엽송 소경각재(단면 $89{\times}120mm$)를 초음파법, 종진동법, 소하중법의 비파괴 방법으로 탄성계수를 측정하였다. 실측 탄성계수와 유의성이 높은 비파괴 측정 방법을 결정 후 휨 파괴계수 예측 지표로 적용하였다. 종진동법으로 측정된 탄성계수가 실측 탄성계수와 가장 높은 유의성을 나타냈다. 휨 파괴계수와 실측 탄성계수의 유의성도 매우 밀접하게 측정되었으므로 종진동법에 의한 비파괴 탄성계수로 소경각재의 휨 파괴계수를 예측하였다.

• Journal of the Korean Wood Science and Technology
• /
• 제25권1호
• /
• pp.15-22
• /
• 1997

The effectiveness of presteaming for improving CCA treatability on refractory Japanese larch heartwood was investigated in this study. Presteaming was effective on improving treatability, and the extent of improvement was dependent on moisture contents of wood specimen and steaming conditions. Green wood showed higher average value in both preservative retention and penetration than dry wood, and steaming under pressure conditions also had higher treatability than steaming at atmospheric conditions. The degree of improvement for treatability was increased with the extension of steaming period. Treatability of dry wood pres teamed under pressure conditions more than 6 hours and green wood for 3 hours was similar to that enhanced by conventional incising. Presteaming green wood under pressure conditions more than 6 hours was more effective than conventional incising in improvement of CCA treatability, and resultant treatability satisfied a minimum value required for CCA-treated wood for being used at the regions of hazard class H3 and H4. In addition, an improvement of treatability by presteaming was due to an increase in permeability resulted from the degradation of hemicelluloses within aspirated pit membrane and cell wall, not the removal of extractives from pit membrane. The reduction in strength, measured as longitudinal compressive strength, due to pres teaming was related with the degradation of hemicelluloses, and was increased as steaming conditions were severe. The degree of strength reduction associated with presteaming treatment to obtain required treatability could be quantified from the relatively good relation between the increase in treatability and the decrease in strength.

• Journal of the Korean Wood Science and Technology
• /
• 제44권4호
• /
• pp.607-615
• /
• 2016

The delamination along the annual ring on the cross-section of laminae and the bonding strength according to the tangential angle between laminae were evaluated for the production of 3-ply cross-laminated timber (CLT) using domestic larch. Since there is no standard for CLT in Korea, the production and test of specimens for bonding strength followed the standard procedure of "Structural glued laminated timber" (KS F 3021). The standard specifies to exclude any measurement from the cracks of timbers resulted from drying or knots during delamination test of the glued laminated timbers. However, the failure of cross-sectional tissues along the annual rings was observed near the glue-line of all specimens during the delamination test. Because this phenomenon can generate defects in the CLT that may be exposed to various temperatures and relative humidities after the actual construction, the delamination percentage was measured by including this wood failure. As a result, the delamination percentage of the CLT which had been combined in such a way that the annual rings of outer lamina were directed inward was the lowest, which was around 13%, regardless of the annual ring direction of the middle lamina. On the other hand, the delamination percentage of the CLT which had been combined in such a way that the annual rings of outer lamina were directed outward was the highest, which was around 26%. Furthermore, end-split occurred in the outer lamina during the drying process of the boiling delamination test, which affected the delamination percentage. Therefore, the soaking delamination test was found to be more appropriate for evaluating the delamination strength of CLT. The block shear strength of larch CLT was $3.9{\pm}0.9$ MPa on average, which was 46% lower than the block shear strength requirement (7.1 MPa) of the standard, but satisfied the criteria of the block shear strength (3.5 MPa) of the European Standard (prEN 16351: 2013).

• Journal of the Korean Wood Science and Technology
• /
• 제21권3호
• /
• pp.30-36
• /
• 1993

Wood chips of oak (Quercus mongolica) and larch (Larix leptolepis) were treated with a relatively low pressure steam(10~20 kg/$cm^2$) for 10~20 min (first-stage),and then increased pressure up to 30kg/$cm^2$ for 30 second (second-stage), and steam pressure was released intentionally to air. Main components of exploded wood were separated with 1% NaOH and hot water-methanol. In this work, the more effective low pressure explosion condition and separation method of wood main component were investigated. The results can be summarized as follows; 1. The yields of exploded wood were generally decreased with increasing steam pressure and reaction time. 2. The proper condition of steam explosion in low pressure for the separation of wood main components was 15kg/$cm^2$-10 min, in oak wood and 20kg/$cm^2$-10 min., then 30kg/$cm^2$-0.5 min, in larch wood. 3. The 23% of elude hemicellulose was obtained from the exploded oak wood which was treated with optimal condition. 4. In the case of hot water-methanol extraction, the ratio of delignification was 14~23% in the exploded larch wood and 42~55% in the exploded oak wood. 5. The methanol was more effective than 1% sodium hydroxide solution for extraction of lignin from exploded wood.

• Journal of the Korean Wood Science and Technology
• /
• 제47권5호
• /
• pp.547-556
• /
• 2019

Thinned, small larch logs have small diameters and no value-added final use, except as wood chips, pallets, or fuel wood, which are products with very low economic value; however, their mechanical strength is suitable for structural applications. In this study, small larch logs were sawed, dried, and cut into square timbers (with a $90mm{\times}90mm$ cross section) that were laterally glued to form core panels used to manufacture cross-laminated timber (CLT) wall panels. The surface and back of these core panels were covered with 12-mm-thick structural plywood panels, used as cross bands to obtain three-ply CLT wall panels. This attachment procedure was conducted in two different ways: gluing and pressing (CGCLT) or gluing and nailing (NGCLT). The size of the as-manufactured CLT panels was $1,220mm{\times}2,440mm$, the same as that of the plywood panels. The final wall panels were tested under lateral shear force in accordance with KS F 2154. As the lateral load resistance test required $2,440mm{\times}2,440mm$ specimens, two CLT wall panels had to be attached in parallel. In addition, the final CLT panels had tongued and grooved edges to allow parallel joints between adjacent pieces. For comparison, conventional light-frame timber shear walls and midply wall systems were also tested under the same conditions. Shear walls with edge nail spacing of 150 mm and 100 mm, the midply wall system, and the fabricated CGCLT and NGCLT wall panels exhibited maximum lateral resistances of 6.1 kN/m (100%), 9.7 kN/m (158%), 16.9 kN/m (274%), 29.6 kN/m (482%), and 35.8 kN/m (582%), respectively.

• Journal of the Korean Wood Science and Technology
• /
• 제30권2호
• /
• pp.102-107
• /
• 2002

본 연구는 낙엽송(Larix Kaemferi Carr.)재를 이용하여 100℃부터 180℃까지의 고온영역에서 20℃ 간격으로 처리시간을 10분, 30분, 60분, 90분간으로 하여 처리조는 봄베를 사용하였다. 1) 고온수증기처리의 처리시간이 길고, 처리온도가 높을수록 밀도의 감소도 커졌다. 2) 밀도의 감소에도 불구하고 고온수증기처리재의 수축율이 control재와 비교하여 비슷하거나 높게 나타나는 것은 수증기처리에 의하여 세포벽 내부의 구성성분 및 구조변화에 의하여 야기된 것으로 판단된다. 3) 고온수증기처리에 의하여 추정목재의 틀어짐은 감소되었다.