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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Wood Science and Technology
Journal Basic Information
Journal DOI :
The Korean Society of Wood Science Technology
Editor in Chief :
Volume & Issues
Volume 27, Issue 4 - Dec 1999
Volume 27, Issue 3 - Sep 1999
Volume 27, Issue 2 - Jun 1999
Volume 27, Issue 1 - Mar 1999
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Effect of Superoxide Dismutase and Low Molecular Mediators on Lignin Degradation
Leonowicz, Andrzej ; Matuszewska, Anna ; Luterek, Jolanta ; Ziegenhagen, Dirk ; Wojtas-Wasilewska, Maria ; Hofrichter, Martin ; Rogalski, Jerzy ; Cho, Nam-Seok ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 1~14
As the biodegradation of wood constituents has been understood as a multi-basidiomycetes and enzymatic processes, this review will focus on the roles of low molecular compounds and radicals working in harmony with fungal enzymes. Wood rotting basidiomycete fungi penetrate wood, and lead to more easily metabolize carbohydrates of the wood complex. The white-rot fungi, having versatile enzymes, are able to attack directly the "lignin barrier". They also use a multi-enzyme system including so-called "feedback" type enzymes allowing for simultaneous degradation of lignin and carbohydrates. The multi-enzymes including laccase support the proposed route by explaining how the high molecular weight enzymes can function in the wood complex. These enzymes may function separately or cooperate each other. In addition, veratryl alcohol oxidase, cellobiose dehydrogenase, arylalcohol dehydrogenase, and particularly low molecular mediators and radicals have an important role in wood biodegradation. However, the possibility of other mechanism as well as other enzymes, as operating as feedback systems in the process of wood degradation, could not be excluded.
Species Identification of Wood Coffins in Chosun Dynasty Period Excavated in Andong Area
Eorn, Young-Geun ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 15~19
Three wood coffins of Chosun Dynasty period buried about 450 years ago were excavated in the sound condition in Andong area in the early 1998. The proprietors of wood coffins were grandparents, Mr. Myoung Jong Lee and Mrs. Mun, and their grandson, Mr. Eung Tae Lee, and the social standing of their family was known to belong to the nobility in those days by the clan genealogy. All the wood coffins investigated through light microscopy had same anatomical characteristics as follows: abrupt to somewhat abrupt tracheid transition from earlywood to latewood; normal longitudinal and horizontal resin canals with thin-walled epithelium; tylosoids in resin canals; bordered pits frequently in 1 row on radial walls of tracheids; 1 or 2 window-like pits per cross-field; uniseriate and fusiform rays; heterogeneous rays composed of body ray parenchyma cells and marginal ray tracheids or homgeneous rays composed of only ray tracheids; dentate ray tracheids; occasional trabeculae traversing tracheids in radial direction. Based on theses microscopic characteristics, all the wood coffins were identified to be Korean red pine (Pinus densiflora) or Korean black pine (Pinus thunbergii). Korean black pine growing naturally in coastal area might not be probable because the site of excavation, Andong area, was mountainous and inland area of Korea Thus, Korean red pine was thought to be the possible species for the wood coffins because of its natural distribution through the Korean Peninsula and the easy availability.
The Effect of Exposure in Elevated Temperatures on Bending Properties of Wood
Park, Joo-Saeng ; Lee, Jun-Jae ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 20~29
Temperature has important effect on mechanical properties of wood. These effect needs to be understood and taken into account in the structural use of wood. Furthermore, the effect of cooling after exposing to high temperature must be explained. In this study, the effect of temperature, exposure time, specific gravity, and cooling on bending properties were investigated. The boundary temperatures at which bending MOE and MOR reduced rapidly were approximately
, respectively. This boundary temperature was nearly constant with independence of species(specific gravity), exposure time, and cooling. Above the boundary temperature, the effect of exposure time was increased with temperature and the reduction of bending MOE and MOR for Japanese Larch with relatively higher specific gravity was smaller than that of Hem-fir. The recovery of bending MOE and MOR after cooling was also more significant above the boundary temperature than below. The degree of cooling effect was larger for MOR than MOE. Consequently, bending properties of wood in elevated temperatures should be considered in terms of the boundary temperature,
for bending MOE,
for MOR, and these boundary temperatures must be considered an important factor. Furthermore, to evaluate the safety of structure, the recovery after cooling should be considered.
Effect of Heat Treatment on the Dimensional Stability and the Bending Properties of Radiata Pine Sapwood
Yun, Ki-Eon ; Kim, Gyu-Hyeok ; Kim, Jae-Jin ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 30~37
The effects of heat treatment on the dimensional stability and bending properties of radiata pine sapwood were investigated. The dimensional stability was almost achieved by heat treatment though the loss of strength was accompanied as a negative effect. The improvement in dimensional stability of wood and the resultant reduction in bending properties were closely related to treatment temperature and duration. The optimum treatment conditions, which could be used to achieve a desired improvement in dimensional stability with resultant losses in modulus of rupture were proposed based on the results obtained in this study.
Nondestructive Estimation of Average Wood Moisture Content Using Surface Temperature Rise by Radiation Heating and Moisture Gradient
Lee, Hyoung-Woo ; Kim, Byung-Nam ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 38~42
Average moisture content of 30mm-thick Korean red pine(Pinus densiflora) was estimated nondestructively and continuously using surface temperature rise by radiation heating and moisture gradient profile in wood. The surface temperature rises increased as surface moisture contents decreased and good relationships were found between surface moisture contents and surface temperature rises at three different feed speeds of 10, 20 and 30 m/min. Average moisture content could be described as a function of surface moisture content and wood thickness.
Stress Wave Technique for Detecting Decay of Structural Members in Ancient Structures
Lee, Jun-Jae ; Oh, Jung-Kwon ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 43~50
The safety-evaluation of ancient wood structures has been executed with only visual inspection. The application of NDE(nondestructive evaluation) is required because the visual inspection has many restrictions. Among many NDE techniques, the stress wave technique was used in this research. This study focused on evaluating the extent of decay in members of ancient structures, using stress wave nondestructive technique. For application of stress wave technique to ancient structures, the threshold time which divides members into categories according to degree of decay should be determined in advance. Stress wave timer (Metriguard Model 239A) was used in this study, specimens used in this research were the members obtained from six ancient structures. All specimens were identified as Hard Pine(Pinus densiflora S. et Z. or Pinus thunbergii P.) by microscope. Each member was tested with stress wave passing radially through the pith. In this study, the stress wave time of
/cm could distinguish between sound and decayed specimens with accuracy of 77.5 percent. Also, decayed specimens could be separated into moderate and severe categories by stress wave time of
/cm. Among the three decay location groups (exterior, mixed, interior), the exterior group could be classified into sound, moderate and severe decay with the greatest accuracy. Stress wave transit time was not sensitive to small decay pockets located in interior of the member.
Criteria of Surface Check under Stepwise Loadings of Drying Stresses
Park, Jung-Hwan ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 51~56
Finite element method was utilized to analyze crack tip stress and displacement field under drying stress case as stepwise loading. Opening mode of single-edge-notched model was employed and analyzed by linear elastic fracture mechanics of plane stress case. The drying stresses were applied as stepwise loads at the boundary elements of the model with 10 steps of time serial. The stress intensity factor(
) for opening mode reached to its maximum just prior to the stress reversal. The
from the displacement fields revealed 1.7 times higher than those from stress fields. By comparing the two sets of
from displacement and stress fields, single parameter
showed its validity to characterize displacement fields around the crack tip front while stress field could not be characterized due to large variations between two sets of data.
Effects of Density, Resin and Particle Types on Properties of Composites from Wood Particle Mixed with Coating Paper
Lee, Phil-Woo ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 57~64
This research was carried out to investigate the effects of density, resin and particle types on the physical and mechanical properties of the composites made from various wood particles mixed with coating paper. The experiment was designed to apply with three particles (flake, chip, and fiber) and three resin types (urea, phenol and PMDI resin). The mixed ratio of coating paper to wood particle was fixed on 50 to 50% in each board making. And also it was designed to apply for four density levels (0.6, 0.7, 0.8 and 0.9 g/
) and four mixed formulations of coating paper to wood particle (10:90, 20:80, 30:70, and 40:60 %) to analyze clearly the effects of PMDI resin. Coating paper-wood particle composites have acceptable bending strength (MOR, MOE) though the mixed ratio of coating paper was increased, but have low internal bond strength and poor dimensional stability (WA, TS, LE). Composites with high density had higher mechanical properties but showed lower physical properties than composites with low density. In conclusion, at least up to 20% mixed ratios, coating paper-wood particle composites have acceptable physical and mechanical properties, and PMDI resin has possibility for coating paper-wood particle composite manufacture.
Bleaching of Hardwood Kraft Pulp by Xylanase Pretreatment
Cho, Nam-Seok ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 65~71
This study was carried out to investigate the effect of xylanase pretreatment of the unbleached hardwood kraft pulp during the conventional Chlorine-Extraction- Hypochlorite (CEH) bleaching on pulp property. Optimum bleaching condition was evaluated by using Novozym produced from the fungus Humicola insolens. Also the effect of chelating agent prior to enzyme treatment was analyzed. The kappa number of enzymatic bleached pulp at the enzyme charge 10 IU/ml was slightly similar to that of bleached pulp without enzyme. By enzyme treatment, the chlorine charge in conventional CEH bleaching process of hardwood KP could be reduced by 17%, while no adverse effect on pulp yield and strength was. The optimum condition for enzyme pretreatment was 10 IU/ml xylanase charge, 3 to 4 hrs treatment, and 2% pulp consistency. In sugar composition in the enzyme pretreated pulp, arabinose and mannose were not much different, but more xylose was retained. This high content of hemicellulose in pulp seems to play an important role in pulp properties. The pulp pretreatment by chelating agent prior to enzyme treatment could improve the enzyme activity and enhance the bleaching effect at 0.2% diethylenetriamine pentaacetic acid (DTPA) charges.
The Effects of Wood Rotting Fungi and Laccase on Destaining of Dyes and KP Bleaching Effluen
Cho, Nam-Seok ; Park, J.M. ; Choi, T.H. ; Matuszewska, A. ; Jaszek, M. ; Grzywnowicz, K. ; Malarczyk, E. ; Trojanowski, K. ; Leonowicz, A. ;
Journal of the Korean Wood Science and Technology, volume 27, issue 4, 1999, Pages 72~79
The ability of several wood rotting fungi for decolorization of two anthracene derivatives, Carminic acid (CA) and Remazol brilliant blue R (RBBR), and hardwood KP bleaching liquor (BL) as well as laccase activities in these fungi were studied. The enzyme activity appeared exclusively in fungi destaining RBBR and CA, but in the case of BL, such relationship was not observed. The laccase enzyme was released into the decolorization media and its inducible (but not constitutive) forms shown destaining activity. The purified inducible forms of Kuehneromyces mutabilis and Pleurotus ostreatus laccase destained CA. Thus the possible differentiation between specificity of particular LAC forms was confirmed. In addition the nitrogen starvation induced both laccase and CA destaining activities, but the increase was higher for decolorization of CA than LAC activity. Probably LAC would be only partly responsible for decolorization of this dye. This results suggested that purified LACs decolorize CA, however its destaining activities were considerably lower than the activities on syringaldazine.