• 제목/요약/키워드: small-diameter logs

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낙엽송 소경재(小徑材)의 제재이용구조(製材利用構造)에 관(關)한 연구(硏究) (A Study on Sawing and Utilization Structure of Lumber from Small - diameter Logs of Larix leptolepis)

  • 이춘택;김수창
    • Journal of the Korean Wood Science and Technology
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    • 제18권3호
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    • pp.53-68
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    • 1990
  • This research has been executed for maximization of lumber yield and more efficient use of small diameter logs. Sample logs from thinnings carne from densed artificial stands at the Kwangnung Experimental Forests situated in the central region of Korean peninsula. Species of sample logs were obtained to execute sawing and strength test for larch, and lumber strength test in full size for pitch pine and Korean pine. A survey on sawmills consuming domestic logs was carried out to know sawmill production, costs and utilization structure of lumber as a guide to business analysis. Results showed that sawing pattern from small logs less than 15cm in diameter was necessary to cut 9cm by 9cm square per one log in order to obtain high lumber recovery and provide for wide market needs. The total lumber yield of squares plus side boards was 56 percent to 58 percent from small logs and the yield for log sweep in 30 percent decreased by 24.5 percent in sawing production, compared to yield for straight logs. In sawing efficiency, production of lumber by twin band saw could be improved 238 percent higher than lumber of the same species produced by conventional sawmilling methods, and sawing accuracy with twin band saw was much higher at the lumber production than band saw. Lumber from the small larch logs has shown 70 knots per $m^2$ on its faces and also lumber showed lots of face checkings by air drying on the yard, compared to other species. MOR in bending of lumber in full size from small logs of larch was found ranging from 380kg/$cm^2$ to 460kg/$cm^2$, resulting in 40 percent less than the strength from clear small specimens. In lumber containing knots, cross grain, etc, longitudinal stress wave speed was delayed about 48 percent by defects in lumber from both larch and pitch pine logs. The surveyed sample sawmills consumed the domestic logs at the rate of 54 percent to 84 percent in the total timber consumption, showing high consumption at mills located in the mountains.

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비파괴 시험방법을 이용한 낙엽송재 원목의 휨강도 특성 평가 (Bending strength assessment of Larix logs by nondestructive evaluation techniques)

  • 박준철;홍순일
    • 임산에너지
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    • 제22권2호
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    • pp.60-68
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    • 2003
  • 목재의 기계적 특성을 평가하기 위하여 여러 가지 비파괴 측정 기술이 도입되고 있다. 본 실험은 낙엽송(Larix kaempferi Carr.) 소경재 원목을 초음파의 통과 속도와 종진동의 고유진동수를 이용한 비파괴 측정 기술로 영계수를 측정하여 휨강도 실험을 통해 얻은 실측 영계수와 휨파괴계수의 상관관계를 검토하였다. 실험에는 50본의 소경재 원목이 사용되었다. 종진동의 고유진동수를 이용한 영계수와 실측 영계수는 비교적 높은 상관관계를 나타내었다. 초음파를 이용한 비파괴 영계수 측정은 옹이의 출현빈도가 높은 원목의 선별에 효과적이었으며 종진동의 고유진동수를 이용한 측정은 할렬의 출현빈도가 높은 원목의 선별에 효과적임을 확인하였다.

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국산 간벌 소경재를 이용한 다중접착접합 기둥부재의 압축강도성능 (Compression strength performance of multi-layer glued columns by using square lumbers produced from domestic small diameter logs)

  • 신일중;김윤희;장상식
    • 농업과학연구
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    • 제38권3호
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    • pp.533-540
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    • 2011
  • This study is to develop a mulit-layer glued columns for construction of Korean-style houses by using domestic small diameter logs. Dried small square lumber glued each other to develop a multi-layer glued columns and evaluated its performance of strength. Then, predicted the design load of multi-layer glued columns and make a comparison between actual load and design load of multi-layer glued columns. In the results, allowable load by allowable stress of multi-layer glued columns was measured one-third of actual columns load and prediction load was measured less than 10~30% of the actual load. Therefore, muilt-layer glued member has a standard allowable stress of compressive of 13 MPa (Larix leptolepis) and 19 MPa (Chamaecyparis obtusa) when used as columns. Also, using compression strength of small diameter square logs could calculate maximum loads of multi-layer glued member as column.

잣나무 소경재의 재질평가를 통한 실내장식용재 개발 (A Development of Interior Decoration Timber with Pinus koraiensis Small Diameter Logs)

  • 박병호;김남훈
    • Journal of Forest and Environmental Science
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    • 제28권4호
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    • pp.268-277
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    • 2012
  • Among the domestic softwoods, technical value of Pinus koraiensis small diameter logs which have comparatively low applicability was evaluated and sensitive characteristics and physical characteristics were investigated and analyzed for examining if it can be utilized as the interior decoration material. For the sensitive characteristics of Pinus koraiensis, wood figure, wood grain, wood color and odor were evaluated and for the physical characteristics, growth-ring width and latewood percentage, abrasion, density, shrinkage, swelling, absorption, roughness and hardness were evaluated. Then, the possibility to be developed as the interior decoration material was found. As the result of evaluating sensitive characteristics and physical characteristics of domestic Pinus koraiensis, wood figure, wood grain, color and scent clearly were judged to have excellent visual factor as the interior decoration material. And, physical characteristics were also judged to be excellent, so it is judged to be developed as the interior decoration material. Therefore, as the result of various forms of design pattern with domestic Pinus koraiensis small diameter logs, several patterns of interior decoration can be developed by characteristics of each side and colors of heartwood and sapwood. And, in the future, it can be applied to furniture design or interior decoration material for the proper use. Especially, it is considered to contribute to wood applying industry through the study on the quality of domestic small diameter logs which have low applicability.

소경재를 이용한 통직집성재의 휨강도 특성 (Bending Strength Properties of glulam made from small diameter logs.)

  • 박준철;홍순일
    • 한국가구학회지
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    • 제13권2호
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    • pp.11-18
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    • 2002
  • This study was carried out to investigate the strength and technical feasibility of glulam from small diameter Pinus densiflora and Larix kaempferi. Small diameter logs are currently not used in structural laminated beam construction, but it is suggested that its properties may be feasible for this purpose. The glulam combinations were designed with high grade laminae located at outer laminations (face) and low grade laminae located at center laminations. Important problems of finger jointed glulam as a structural beam are the small modulus of rupture (MOR). One solution for this problem Mi to use veneer and solid wood as the face laminae. The MOE values were predicted for each beam from laminae. The results showed that actual beam MOE values exceeded slightly the predicted values. Based on the evaluation and analysis of Pinus and Larix glulam, the maximum load of Larix kaempferi glulam indicated large values. The bending properties of A and E types glulam were superior to others. It is suggested that this small diameter log can be a candidate for structural glulam construction, providing the proper combinations of face laminae.

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Log Production of Major Commercial Species for Sawtimber in Hongcheon Region of South Korea

  • Lee, Ilsub;Lee, Daesung;Seo, Yeongwan;Choi, Jungkee
    • Journal of Forest and Environmental Science
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    • 제33권3호
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    • pp.233-238
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    • 2017
  • This study was carried out to figure out the number of logs for sawtimber by DBH and height class and to compare merchantable volume ratio by categorizing into sawtimber, lagging board and pulpwood, and others for Pinus densiflora, Pinus koraiensis, and Larix kaempferi. Logs for sawtimber were hardly produced in small DBH class of three species, but produced evidently from medium DBH class. In large DBH class, the number of logs for sawtimber were noticeably different among species: 4.3 logs for L. kaempferi, 2.6 logs for P. densiflora, and 1.0 logs for P. koraiensis on average. Similarly, merchantable volume ratio for sawtimber were largely different among species in large DBH class with higher than 15 m: 82% logs for L. kaempferi, 60% logs for P. densiflora, and 44% logs for P. koraiensis. When compared to the upper diameter and upper height by species with regard to the last log of a tree produced for sawtimber, upper diameter was smallest with 14.1 cm and upper height was highest with 12.2 m in L. kaempferi. Overall, L. kaempferi was considered as the more commercial species for sawtimber production than P. densiflora and P. koraiensis.

Evaluation of Strength Properties for Bolted Connections with Lumber from Small Diameter Logs

  • Park, Joo-Saeng;Park, Chun-Young;Chun, Su-Kyoung;Lee, Jun-Jae
    • Journal of the Korean Wood Science and Technology
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    • 제30권3호
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    • pp.59-65
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    • 2002
  • EYM (European Yield Model), which was adopted in NDS (National Design Specification for wood construction), has been used in Korea without any verification of the analysis of bolted wood connections. In the case of applying lumber from domestic small diameter logs, however, there are some problems with the direct application of EYM ; 1) relatively low dowel bearing strength and dimensional stability due to a large amount of immature wood, 2) effect of MC (moisture contents) on the dowel bearing strength of wood and the yield load of a bolted connection. To evaluate the strength properties of bolted connections with lumber from domestic small diameter logs, effect of MC on the dowel bearing strength of wood was investigated and double shear bolted connection tests were performed. As the MC of wood increased, the dowel bearing strength was linearly reduced, even under 19% MC, which showed that adjustment, not considered in NDS, was required. Double shear bolted connection tests indicated that effect of MC on yield load should be considered in order to determine design value.

Computing the Bucking Rate of Japanese Larch Logs for Timber Harvesting

  • Daesung Lee;Yonghee Lee;Ilsub Lee;Jungkee Choi
    • Journal of Forest and Environmental Science
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    • 제40권1호
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    • pp.35-42
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    • 2024
  • The Japanese larch (Larix kaempferi [Lamb.] Carriere) is a major timber species in Korea. However, studies on bucking rates and merchantable logs of this species are insufficient in South Korea. To bridge these gaps, in this study, the bucking rate of Japanese larch (Larix kaempferi [Lamb.] Carriere) was computed and the number of long logs and merchantable log volumes were analyzed. Sample trees were bucked according to the log grade for trading, and collected from a forest field in Gangwon Province. The bucking rate of all Japanese larch logs was >89%. The highly profitable 2-4 logs of 3.6 m length from trees with ≤30 cm diameter at breast height (DBH) and 5-6 logs with ≥34 cm DBH were produced. The bucking rate of long logs was >84%; thus, Japanese larch was found to be suitable for the supply of high-grade timber. Additionally, to follow reasonable wood supply plans, merchantable volume tables were offered based on 3.6 m-long number of logs and small-end diameter classes. Understanding the proportion of merchantable log volumes, bucking rates, and the number of long and short logs has large-scale applications in practical forestry.

Nail Withdrawal Behavior for Domestic Small Diameter Logs

  • Cha, Jae-Kyung
    • Journal of the Korean Wood Science and Technology
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    • 제30권3호
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    • pp.104-108
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    • 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.

수간부위 형상 시뮬레이션을 이용한 임목 이용재적 및 목재수율 추정 (Estimation of Merchantable Volume and Yield Using A Stem Shape Simulation)

  • 권순덕;김형호;정주상
    • 한국산림과학회지
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    • 제96권3호
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    • pp.362-368
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    • 2007
  • 본 연구는 잣나무와 낙엽송을 대상으로 흉고직경급에 따른 임목의 용도별 이용재적 및 목재수율을 산출하기 위해 수행되었다. 먼저 기존에 개발된 수간곡선, 수고 추정식을 이용하여 입목의 형상에 따른 수간 재적량을 산출하였다. 그리고 일반용재와 펄프재의 이용재적 및 조재수율, 일반용재를 판재 및 각재로 가공했을 때 제재목의 이용재적 및 조재수율을 직경급별로 산출하였다. 연구결과에 따르면 수간재적에 있어서 낙엽송의 재적이 잣나무보다 동일한 흉고직경급에 있어서 23~38% 높게 나타났다. 일반용재 생산은 2개 수종 모두 흉고 직경급 18 cm부터 가능하였다. 또한 일반용재와 펄프재용 원목의 조재수율 합계는 흉고직경이 커지는 초기에 급격하게 증가하였고 잣나무의 경우 흉고직경 26 cm에서 90%, 낙엽송의 경우 흉고직경 38 cm에서 88%로 최대로 나타났다. 한편 판재의 조재수율은 23~56%, 각재는 그 생산크기가 커질수록 조재수율이 떨어지는 것으로 나타났다. 이 연구의 결과는 산림의 이용재적 산출 및 임목평가 그리고 제재목의 결정에 활용될 수 있을 것이다.