• Title/Summary/Keyword: wood grain

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Lateral Compression and Dowel Bearing Property of Japanese Larch Grown in Korea (국산 낙엽송재의 횡압축과 다우얼 지압 성능)

  • Hwang, Kweonhwan;Park, Byung-Su
    • Journal of the Korean Wood Science and Technology
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    • v.36 no.3
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    • pp.61-69
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    • 2008
  • To examine the compression properties of structural members, the compression and bearing tests were conducted in parallel- and perpendicular-to-grain loading using domestic Japanese larch (Larix kaempferi (Lamb.) Carriere). Compression (bearing) properties with the length of a specimen and the contact length of the bearing plate were investigated, and deformations at each specimen length from the point of bearing force were measured to evaluate the effective end distance tabulated in the present practice (Korean Building Code). Compression (bearing) properties varied with the size of the bearing plate, and the end distance for dowel-type fastener taken into consideration of the specimen's deformation, for the safe design, should be applied with over 7 D.

Evaluation of Physical Properties of Korean Pine (Pinus koraiensis Siebold & Zucc.) Lumber Heat-Treated by Superheated Steam (과열증기 열처리 잣나무재의 물성 평가)

  • Park, Yong-Gun;Eom, Chang-Deuk;Park, Jun-Ho;Chang, Yoon-Seong;Kim, Kwang-Mo;Kang, Chun-Won;Yeo, Hwan-Myeong
    • Journal of the Korean Wood Science and Technology
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    • v.40 no.4
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    • pp.257-267
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    • 2012
  • In this study, the method for heat treating wood using superheated steam (SHS) was designed and applied. The physical and mechanical properties of Korean Pine (Pinus koraiensis Siebold & Zucc.) lumber heat-treated by SHS at $170^{\circ}C$ and 0.4 MPa for 10 hours were compared with those of non-treated and normal heat-treated wood. The amount of adsorbed water and equilibrium moisture content of the SHS treated wood were lower than non-treated wood. On the other hand the compressive strength parallel to grain and the bending strength of SHS treated wood were higher than those of non-treated wood. The hygroscopicity of SHS treated wood was similar to normal heat treated wood at $220^{\circ}C$. Internal checks that often occur during normal heat treatment were not developed at SHS treatment. Also, SHS treatment are effective in control of internal checks occurrence and resin exudation.

A Study on the Block Shear Strength according to the Layer Composition of and Adhesive Type of Ply-Lam CLT (Ply-Lam CLT의 층재 구성 및 접착제 종류에 따른 블록전단강도에 관한 연구)

  • CHOI, Gyu Woong;YANG, Seung Min;LEE, Hyun Jae;KIM, Jun Ho;CHOI, Kwang Hyeon;KANG, Seog Goo
    • Journal of the Korean Wood Science and Technology
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    • v.48 no.6
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    • pp.791-806
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    • 2020
  • In this study, a block shear strength test was conducted to compare and analyze the strength and failure mode on the glued laminated timber, CLT, and Ply-lam CLT, which are mainly used for the construction of wood construction as engineering wood. Through this, the Ply-lam CLT manufacturing conditions for optimum production, such as the type of lamina, plywood, adhesive, and layer composition, were investigated. The results are as follow. Through block shear strength test, it showed high strength in the order of glued laminated timber, Ply-lam CLT and CLT. In particular, the shear strength of Ply-lam CLT, which is made of a composite structure of larch plywood and larch lamina, passed 7.1 N/㎟, which is a Korean industrial standards for block shear strength of structural glued laminated timber. In addition, in this study, there was no different in shear strength according to the adhesive type used for glulam, CLT, and Ply-lam CLT adhesion. However, in the case of Ply-lam CLT, the difference in shear strength of Ply-lam CLT was shown according to the type of lamina and plywood. The results showed high strength in the order of Larix kaempferi > Mixed light hardwood ≒ Pinus densiflora, sieb, et, Zucc plywood. The optimal configuration of Ply-lam CLT is when larch plywood and larch lamina are used, and it is decided that the adhesive can be used by selecting PRF and PUR according to the application. The results of block shear strength failure mode by type of wood based materials were analyzed. The failure mode showed shear parallel-to-grain for glulam, rolling shear for CLT, and shear parallel-to-grain and rolling for ply-lam CLT. This is closely related to shear strength results and is decided to indicate higher shear strength in Ply-lam CLT than in CLT due to rolling shear.

Effect of Kerfing and Incising Pretreatments on High-Temperature Drying Characteristics of Cedar and Larch Boxed-Heart Timbers with Less than 150 mm in Cross Section Size (배할 및 인사이징 전처리가 횡단면 크기 150 mm 이하 삼나무와 낙엽송 수심재의 고온건조특성에 미치는 영향)

  • LEE, Chang-Jin
    • Journal of the Korean Wood Science and Technology
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    • v.48 no.3
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    • pp.345-363
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    • 2020
  • This study was conducted to identify the effect of kerfing and incising pretreatments on high-temperature drying characteristics of cedar and larch boxed-heart timbers with a cross section of less than 150 mm. The result showed that the pretreatments have made a significant difference regarding surface check and shrinkage. Although the kerfing was suitable as a pretreatment to reduce the occurrence of surface check, the incising was not suitable as a pretreatment since the knives of timber joined together, causing the conversion to the surface checks. The shrinkage showed a significant result that the final moisture content was reduced in the order of incising, kerfing, and kerfing-incising after the drying process based on the pretreatment condition. Twist was more affected by the grain angle than the anisotropy of the juvenile wood, and there was no effect of pretreatments.

The Verification of Image Merging for Lumber Scanning System (제재목 화상입력시스템의 화상병합 성능 검증)

  • Kim, Byung Nam;Kim, Kwang Mo;Shim, Kug-Bo;Lee, Hyoung Woo;Shim, Sang-Ro
    • Journal of the Korean Wood Science and Technology
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    • v.37 no.6
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    • pp.556-565
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    • 2009
  • Automated visual grading system of lumber needs correct input image. In order to create a correct image of domestic red pine lumber 3.6 m long feeding on a conveyer, part images were captured using area sensor and template matching algorithm was applied to merge part images. Two kinds of template matching algorithms and six kinds of template sizes were adopted in this operation. Feature extracted method appeared to have more excellent image merging performance than fixed template method. Error length was attributed to a decline of similarity related by difference of partial brightness on a part image, specific pattern and template size. The mismatch part was repetitively generated at the long grain. The best size of template for image merging was $100{\times}100$ pixels. In a further study, assignment of exact template size, preprocessing of image merging for reduction of brightness difference will be needed to improve image merging.

Evaluation of Physico-mechanical Properties and Durability of Larix kaempferi Wood Heat-treated by Superheated Steam (과열증기 열처리 낙엽송재의 물리·역학적 성능 및 내후성능 평가)

  • Park, Yonggun;Park, Jun-Ho;Yang, Sang-Yun;Chung, Hyunwoo;Kim, Hyunbin;Han, Yeonjung;Chang, Yoon-Seong;Kim, Kyoungjung;Yeo, Hwanmyeong
    • Journal of the Korean Wood Science and Technology
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    • v.44 no.5
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    • pp.776-784
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    • 2016
  • In this study, green Larix kaempferi lumber was heat-treated by using superheated steam (SHS) at a pilot scale and then various physico-mechanical properties of the heat-treated wood were evaluated and compared with the properties of conventional hot air (HA) heat-treated wood. Decay resistance of brown rot fungi and compressive strength parallel to the grain of the SHS heat-treated wood without occurrence of drying check from green lumber were increased. On the other hand, density, equilibrium moisture content, shrinkage, and bending strength of the SHS heat-treated wood were lower than those of the conventional HA heat-treated wood. Because heat transfer and thermal hydrolysis of SHS heat treatment was accelerated by a large amount of water, the effect of SHS heat treatment on the physico-mechanical properties was higher than that of HA heat treatment at the similar conditions of temperature and time. From the results of this study, because green lumber can be heat-treated without occurrence of cracks or checks by using SHS and similar heat treatment effect on the physico-mechanical properties of wood can be produced despite a low temperature or short time of heat treatment, it is expected that heat time and energy consumption could be reduced by using SHS.

Studies on the Fundamental Properties of the Wood of Gumgangsong(Pinus densoflora for. erecta Uyeki) (Part 1) (강송의 기초적 재질에 관한 연구(제1보))

  • 김정환;이원희;홍선천
    • Journal of the Korea Furniture Society
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    • v.10 no.2
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    • pp.55-61
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    • 1999
  • This research was carried out to investigate the fundamental properties such as the structure of annual ring, density distribution, compressive strength with parallel to grain, relative crystallinity, and microfibril angle of Gumgangsong(Pinus densoflora for. erecta Uyeki). The wood specimens, Gumgangsong and Sonamu(Pinus densiflora S. et Z.), for this experiment were prepared at Ulijingoon Sokwangri and Kyungpook university's forest in Kyungpook province, respectively. Average annual ring width is $2.0mm{\pm}0.3$ in heartwood of Gumgangsong. The respectively of heart wood was over 60 percent in Gumgangsong and 20~50 percent in Sonamu. Heartwood density were ranged from 0.5 to $0.8{\;}g/cm^3$ in Gumgangsong and from 0.4 to $0.5{\;}g/cm^3$ in sonamu. Compressive strength in Gumgangsong and Sonamu was about $30{\pm}5MPa$ and $25{\pm}5MPa$, resepectively. But the relative crystallinity and microfibril angle of two species were not different clearly. From these results of Gumgangsong and Sonamu, therefore, it was considered the main difference factors for both species were annual ring width and heartwood percentage.

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Physical and Mechanical Properties of Local Styrax Woods from North Tapanuli in Indonesia

  • Iswanto, Apri Heri;Susilowati, Arida;Azhar, Irawati;Riswan, Riswan;Supriyanto, Supriyanto;Tarigan, Joel Elpinta;Fatriasari, Widya
    • Journal of the Korean Wood Science and Technology
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    • v.44 no.4
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    • pp.539-550
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    • 2016
  • The objective of this research was to evaluate physical and mechanical properties of three species of Styrax woods from North Tapanuli in Indonesia. The woods were more than 15 years old. Physical properties such as specific gravity, green moisture content, and volume shrinkage were determined by the procedures based on BS-373 standard for small clear specimen. Furthermore, mechanical properties, including modulus of rupture, modulus of elasticity, compression parallel to grain and hardness were also tested according to the standard. Along the stem direction, the edge section had better properties compared with those near the pith section. And the base section had also better properties than upper section. Based on the specific gravity, all of the Styrax woods in this research were classified into III-IV strength classes. A good dimensional stability was demonstrated by the value of the tangential and radial ratio which reached one. With the consideration of the mechanical properties, Styrax woods were suitable use for raw materials of light construction, furniture and handy craft.

Screening and Evaluation of Streptomyces Species as a Potential Biocontrol Agent against a Wood Decay Fungus, Gloeophyllum trabeum

  • Jung, Su Jung;Kim, Nam Kyu;Lee, Dong-Hyeon;Hong, Soon Il;Lee, Jong Kyu
    • Mycobiology
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    • v.46 no.2
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    • pp.138-146
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    • 2018
  • Two-hundred and fifty-five strains of actinomycetes isolated from soil samples were screened for their antagonistic activities against four well-known wood decay fungi (WDF), including a brown rot fungus, Gloeophyllum trabeum and three white rot fungi Donkioporia expansa, Trametes versicolor, and Schizophyllum commune. A dual culture assay using culture media supplemented with heated or unheated culture filtrates of selected bacterial strains was used for the detection of their antimicrobial activity against four WDF. It was shown that Streptomyces atratus, S. tsukiyonensis, and Streptomyces sp. greatly inhibited the mycelial growth of the WDF tested compared with the control. To evaluate the biocontrol efficacy of S. atratus, S. tsukiyonensis, and Streptomyces sp., wood blocks of Pinus densiflora inoculated with three selected Streptomyces isolates were tested for weight loss, compression strength (perpendicular or parallel to the grain), bending strength, and chemical component changes. Of these three isolates used, Streptomyces sp. exhibited higher inhibitory activity against WDF, especially G. trabeum, as observed in mechanical and chemical change analyses. Scanning electron microscopy showed that cell walls of the wood block treated with Streptomyces strains were thicker and collapsed to a lesser extent than those of the non-treated control. Taken together, our findings indicate that Streptomyces sp. exhibits the potential to be used as a biocontrol agent for wood decay brown rot fungus that causes severe damage to coniferous woods.

Hazard Assessment of Explosion in Suspended Dust of Wood (목재 부유분진의 폭발 위험성 평가)

  • Lee, Keun Won;Lee, Su-Hee;Han, Ou-Sup
    • Journal of the Korean Institute of Gas
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    • v.17 no.5
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    • pp.81-86
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    • 2013
  • Accidents of dust explosion has been occurred in various industries as a plastics, pharmaceuticals, timber, grain storage, solid fuels and chemicals. In this study, the silo dust, hammer mill dust and Nyusong dust in the manufacturing process of the particle board to utilize west wood, which were selected for this experiment and were evaluated the characteristics of dust explosion. The explosion characteristics such as a maximum explosion pressure, explosion index, lower explosive limit, and minimum ignition energy in suspended dust of the wood by Siwek 20 L apparatus were measured and evaluated for the experiment. The results of this study can be used the process safety measures to prevent accidents of fire and explosion in the suspended dust of wood.