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리기다소나무 원목형질 조사 및 구조용집성재 제조 수율 평가
심상로,여환명 한국목재공학회 2004 목재공학 Vol.32 No.2
우리나라 전역에 사방 및 연료림으로 대량 식재되어 소기의 목적을 달성함과 동시에 치산녹화 성공을 이루는데 크게 기여한 수종인 리기다소나무 제재목의 구조용집성재 라미나로서의 이용가능성을 고찰하였다. 건전한 임분 내에서 평균 흉고직경 32 ㎝인 리기다소나무를 벌채하여 말구직경 15 ㎝ 이상으로 조재하였을 경우 80% 이상이 2등급 또는 3등급의 원목형질로 구분되어 리기다소나무의 제재목으로서의 이용가능성이 높다고 판단되었다. 구조용집성재 라미나용 주제품의 제재수율은 39.9%. 벽판재 수율은 7.2%, 부제품 수율은 8.1%로 총 원목의 55.2%가 판재로 제재되었다. 옹이를 제거하여 핑거가공한 후 제조한 구조용집성재의 제조수율은 15.3%로 평가되어 옹이를 제거하지 않은 판재의 라미나로의 이용을 위한 옹이채의 휨강도와 압축강도 등의 강도적 성능 평가와 더불어 최적의 라미나 배열을 통한 구조용집성재의 강도 감소 최소화를 위한 연구가 앞으로 필요하다고 판단된다. 본 연구에서 조사된 제재수율과 기타 가공수율 평가는 현재까지 목재산업현장에서 제재목으로의 이용이 거의 이루어지지 않고 있는 리기다소나무의 효율적인 생산계획을 수립하는데 사용되어질 수 있으리라 기대된다. Pitch pine(Pinus rigida) has been planted in Korean forests for several decades, primarily for erosion control and use as a fuel supply. To enhance its value, and especially potential use as lamina for structural glued laminated timber (glulam), log quality and lumber yield of pitch pine were evaluated in this study. Threes from pure pitch pine stands with an average diameter at trreast hight of 32㎝ were felled and bucked into 3.6m long 15㎝ minimum butt-end diameter logs. Over 80% of the logs were classified to No. 2 or No. 3 visual grade group. Upon sawing total lumber yield was 55.2% 39.9% for structural glulam lamina, 7.2% for louver, and 8.1% for miscellaneous use. The final lumber yield for manutacturing structural glulam, after cross-cutting to eliminate knots and finger jointing, was only 15.3%. To enhance this manutacturing yield requires that the rate of knot-included lumber used as lamina be raised. However arrangement of the knot-inclucled lamina, whose mechanical properties need to he accurately evaluated, must be optimized to minimize any reduction to the structural glulam strength. The log quality and lumber yield of pitch pine evaluated in this study are expected to facilitate proper planning for wood product manufacture in the Korean lumbering and glulam industrial field, which has not previously dealt with this species.
심상로(Sang Ro Shim),서진석(Jin Suk Suh) 한국가구학회 1994 한국가구학회지 Vol.5 No.1
This study was carried out under the assembly conditions at company and laboratory, for the purpose of acquiring the available adhesion-joint performance of wooden dowels which are being commonly used in jointing the furniture members.<br/> In laboratory assembly test, Polyvinyl acetate emulsion resin adhesive(room temperature curing type), urethane resin adhesive and MDI resin were applied to the dowels-joint of members of lumber, PB and MDF in a separate use or a mixed use condition, and then their withdrawal strengths were evaluated.<br/> Also, the withdrawal strengths were Investigated according to the elapsed time after gluing and assembly of dowels.<br/> There suits were summarized as follows:<br/> 1. The withdrawal strength was highest at the lowest diameter 6mm of dowel of tested 6, 8 and 10mm at each member in the company assembly condition.<br/> 2. In the laboratory assembly condition, the lumber showed the highest withdrawal strengths, which were subordinated with those at PB and MDF, resulting in th ε almost same withdrawal strengths between two members.<br/> 3. According to the types of adhesive and their formulations, th ε withdrawal strengths by urea resin and urethane resin at both separate use and mixed use condition were higher, comparing to that by a single use of poly vinyl acetate resin adhesive.<br/> 4. In terms of the developing speed of withdrawal strength by the elapsed time after gluing and assembly of dowels, there was a nearly proportional increase until 24 hrs. after assembly at lumber. On the contrary to this, there was a mild increase until about 6hrs. after assembly at PB and MDF, and there after no difference until 24 hrs.<br/> 5. From the above results, it was suggested that th ε handling and conveying of dowels-assembled furniture to other processing or finishing line , if at least 6 hrs. elapse after assembly of dowels at members, can not affect much the withdrawal strengths. Particularly, a good joint strength in this case was obtained with<br/> application of urethane resin mixed- urea resin a adhesive.