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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Wood Science and Technology
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Journal DOI :
The Korean Society of Wood Science Technology
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Volume & Issues
Volume 34, Issue 6 - 00 2006
Volume 34, Issue 5 - 00 2006
Volume 34, Issue 4 - 00 2006
Volume 34, Issue 3 - 00 2006
Volume 34, Issue 2 - 00 2006
Volume 34, Issue 1 - 00 2006
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Microscopic Patterns of Decay caused by Tyromyces palustris and Gloeophyllum trabeum in Korean Red Pine and Radiata Pine Woods
Kim, Hwa-Sung ; Eom, Yeong-Geun ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 1~10
The objective of this study was to elucidate the microscopic patterns of decay caused by brown-rot fungi of Tyvomyces palustvi and Gloeophyllum trabeun~ in Korean red pine (Pinus densiflova) and radiata pine (Pinus vadiata) woods through light and electron microscopies. The ultrastructural changes of cell walls attacked by the two brown-rot fungi were compared in this respect. Macroscopically, radiata pine showed more ring and radial checks than Korean red pine. Microscopically, with the progress of decay, spiral checks associated with cross-field pits and bore holes in the cell wall were more remarkably numerous in the radiata pine than in the Korean red pine. In the radiata pine, G. trabeun~ produced more spiral checks in the cell wall than T. palushis. In the advanced stages of decay by G. trabeun~, the erosions of ray cell walls were identified both in the Korean red pine and radiata pine but Sj layers of tracheid walls were eroded only in the Korean red pine.
Studies on Evaluation for Long-Term Structural Performance of Pinus densiflora Sieb. et Zucc. (Ⅰ)-Shear Creep and Mechano-Sorptive Behavior of Drift Pin Jointed Lumber-
Hong, Sun-Il ; Park, Jun-Cheol ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 11~18
This study was carried out to evaluate the mechano-sorptive deflection of shear creep of drift pin jointed solid wood. Specimens were the solid wood of Pinus densiflova. The joint was composed with steel plate and drift pin, 85mm in length and lOmm in diameter. The creep tests were conducted under the constant loads in an variable environment. Five different shearing loads were applied parallel to the grain of specimens. The shearing loads applied were 170, 340, 510, 680 and 850 kgf. The stress levels were 10, 20, and 30, 40 and 50% of the bearing strength obtained from the tension-type lateral strength test. The creep tests for specimens were carried out for 10300 hours. A few general conclusions could be drawn fiom this study: The mechano-sorptive deflection ( 6 ms) is defined as 6 ms = 6 t - ( 6 c + 6 sh) - 6 o, where 6't is the total deflection, 6 c is the pure creep, 6 sh is shrinkage-swelling behavior, and 6' o is the initial deflection. Changes of relative humidity may cause more severe creep deflection than those of constant humidity, especially during the drying process. The mechano-sorptive behaviors of specimens, except the effects of shrinkage and swelling, gradually increased with increasing time. The deflection is increased in desorption process and recovered in adsorption process. The deflections of drift pin jointed solid wood under different loads showed almost same tendency in all specimens. Although the creep deflection tendencies of each series are very similar, the specimens subjected to a large shearing load exhibit large creep deflections in the desorption process than do those to the small shearing load specimens.
Compression Behavior of Wood Stud in Light Framed Wall as Functions of Moisture, Stress and Temperature
Park, Ju-Saeng ; Lee, Jeon-Je ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 19~28
There has been considerable research in recent tlmes in I~ght-t~mbefra med structures in fires. These structures have included horizontal (floor-like) panels in bending and walls under eccentric and approximately concentric vertical loading. It has been shown that compression properties are the most dominant mechanical properties in affecting structural response of these structures in fire. Compression properties have been obtained by various means as functions of one variable only, temperature. It has always been expected that compression properties would be significantly affected by moisture and stress, as well. However, these variables have been largely ignored to simplifjr the complex problem of predicting the response of light-timber framed structures in fire. Full-scale experiments on both the panels and walls have demonstrated the high level of significance of moisture and stress for a limited range of conditions. Described in this paper is an overview of these conditions and experiments undertaken to obtain compression properties as a functions of moisture, stress and temperature. The experiments limited temperatures to 20- 100~CA. t higher temperatures moisture vaporizes and moisture and stress are less significant. Described also is a creep model for wood at high temperatures.
Reduction of Formaldehyde Emission from Particleboardsby Bio-Scavengers
Eom, Yeong-Geun ; Kim, Hyeon-Jung ; Kim, Jong-Sung ; Kim, Su-Min ; Kim, Jin-A ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 29~41
This study was to investigate the effect of addlng addltive as tannin, rlce husk and charcoal, for reducing the formaldehyde emission level, on the adhesion properties of urea-formaldehyde (UF) resin for particleboard. We controlled the hot-pressing time, temperature and pressure to determine the bonding strength and formaldehyde emission. Blends of various UF resinladditives (tannin, rice husk and charcoal) compositions were prepared. To determine and compare the effect of additives (tannin, rice husk and charcoal) content, 0, 5, 10 and 15%, by weight of UF resin, were used. NH4Cl as hardener added. To determine the level of formaldehyde emission, we used the desiccator, perforator and 20 L-small chamber method. The formaldehyde emission level decreased with increased additions of additive (except rice husk). Also, increased hot-pressing time decreased formaldehyde emission level. At a charcoal replacement ratio of only 1596, the formaldehyde emission level is under F& & & & grade (emit < 0.3 mgl 1 ). Curing of the high tannin additive content in this adhesive system indicated that the bonding strength increased. But, in the case of rice husk and charcoal, the bonding strength was much lower due to the inorganic substance. Furthermore, rice husk was poor in bonding strength as well as formaldehyde emission than tannin and charcoal.
Comparison of Formaldehyde Emission Rate and Formaldehyde Content from Rice Husk Flour Filled Particleboard Bonded with Urea-Formaldehyde Resin
Lee, Yeong-Gyu ; Lee, Hwa-Hyeong ; Kim, Hyeon-Jung ; Yun, Dong-Won ; Kim, Su-Min ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 42~51
The this study, the effect of rice husk flour (RHF) as scavenger on formaldehyde emission rate and formaldehyde content from urea-formaldehyde (UF) resin bonded RHF content wood particleboards (PB). Two type of particle size (30 pm and 300 pm) of RHF was premixed with the UF resin at 5% and 15% by weight. The performance of UF resins is greatly influenced by the curing characteristics in their curing processing. The curing behavior was monitored activation energy (E,) by DSC and pH variation according to RHF contents. PB with dimensions of 27 cm X 27 cm X 0.7 cm was prepared at a specific gravity of 0.75 using El and E2 class UF resins. Formaldehyde emission and formaldehyde content from RHF filled PB bonded with UF resin was measured by 24 h desiccator and perforator method, respectively. RHF causes an increased pH of UF resin. E, of the modified UF resin decreased independently of RHF particle size. As the pH and the E, variation of the UF resin containing RHF increased, the amount of formaldehyde content decreased. The formaldehyde emission and formaldehyde content levels of the PB bonded with 15 wt% of 30 pm RHF and E2 type UF resin were low and satisfied grade El, as measured by 24 h desiccator and perforator method. The result of a comparison between 24 h desiccator and perforator test using PB showed that the linear regression analyses show a good correlation between the results for the 24 h desiccator and the perforator tests. The linear regression of a correlation between the dcsiccator and thc pcrforator was Y=4.842X-0.064 (~~=0.989)R. HF was cffcctivc at rcducing formaldehyde emission and formaldehyde content in urea-formaldehyde adhesives when used as scavenger.
Dimensional Stability of Cement ？ Bonded Boards Manufactured with Coffee Chaff
AJAYI, Babatunde ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 52~58
Coffee chaff for manufacturing of the 6 mm thick cement-bonded boards was obtained from a coffee processing industry at Omuo-Ekiti, in Ekiti State, Nigeria. Boards were produced with three levels of cement to coffee chaff ratio of 1.5: 1, 2.5: 1 and 3.5: 1; and at three levels of mixing curing reagent of 2.0%, 2.5% and 3.0%. Three dimensional properties of thickness swelling (TS), water absorption (WA) and linear expansion (LE) were investigated after 48 hours immersion in water. The mean values obtained for TS, WA and LE ranged from 0.46% to 1.47%, from 11.52% to 24.00%, from 0.19% to 0.35%, respectively. The most dimensionally stable boards were produced at the highest mixing levels of curing reagent and cement to coffee chaff ratio of 3.0% and 3.5:1, respectively. The coffee chaff is suitable as raw material for the manufacture of cement-bonded composites and it would be able to stimulate and activate the use of other agro-byproducts for the manufacture of value-added panels.
Thermal Behavior of Hwangto and Wood Flour Reinforced High Density Polyethylene (HDPE) Composites
Lee, Seon-Yeong ; Do, Geum-Hyeon ; Gang, In-Aeh ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 59~66
The thermal properties of wood flour, Hwangto, and maleated polyethylene (MAPE) reinforced HDPE composites were investigated in this study. The thermal behavior of reinforced wood polymer composites was characterized by means of thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. Hwangto and MAPE were used as an inorganic filler and a coupling agent, respectively. According to TGA analysis, the increase of wood flour level increased the thermal degradation of composites in the early stage, but decreased in the late stage. On the other hand, Hwangto reinforced composites showed the higher thermal stability than virgin HDPE, from the determination of differential peak temperature (DTp). Decomposition temperature of wood flour and/or Hwangto reinforced composites increased with increase of heating rate. From DSC analysis, melting temperature of reinforced composites little bit increased with the addition of wood flour or Hwangto. As the loading of wood flour or Hwangto to HDPE increased, overall enthalpy decreased. It showed that wood flour and Hwangto absorbed more heat energy for melting the reinforced composites. Hwangto reinforced composites required more heat energy than wood flour reinforced composites and virgin HDPE. Coupling agent gave no significant effect on the thermal properties of composites. Thermal analyses indicate that composites with Hwangto are more thermally stable than those without Hwangto.
Characterization and Properties of Composites of Woodflour and Polylactic Acid
Febrianto, Fauzi ; Yoshioka, Mariko ; Nagai, Yuko ; Syafii, Wasrin ; Shiraishi, Nobuo ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 67~78
Modification of polylactic acid (PLA) and 10% maleic anhydride (MAH) with 15% dicumyl peroxide (DCP) based on MAH weight was conducted in the kneader at 160°C and 30-70 rpm, for 15 min. The resulting MAH-modified PLA (PLA-MA) was then evaluated as a compatibilizer for PLA- wood flour (WF) composites. The FTIR and 'H-NMR analysis gave evidence of PLA-MA formation. After kneading and reacting with MAH and DCP, the number (Mn) and the weight average (Mw) molecular weights of PLA decreased as compared to the original PLA. The presence of WF in the composites decreased the tensile strength and several other physical properties. The higher the WF loading resulted in the greater the reduction of tensile strength. An addition of 10% PLA-MA as a compatibilizer to the composites improved the tensile strength and several other physical properties, increased the flow temperature, and decreased the melt viscosity. The improved composite revealed 1.42 times increased in tensile strength but not over PLA alone, and absorbed considerably less water compared to those of the composites free-compatibilizer.
Feasibility of Value-added Utilization of Ash Trees Infested with Emerald Ash Borer
Kim, Jae-U ; Matuana, Laurent M ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 79~87
Value-added utilization of the disposed ash trees due to the infestation by Emerald Ash Borer (EAB) was explored by converting them into particleboards (PBs) and wood-plastic composites (WPCs). The experimental result showed that PB panels could be successfully manufactured from the ash wood but compaction ratio need to be higher than 1.3 in order to meet the standard requirements listed by American National Standards Institute (ANSI). Ash wood plastic composites with high density polyethylene (HDPE) and polypropylene (PP) were also prepared with additives by extrusion. Physical and mechanical properties of ash wood plastic composite compared favorably to those made of pine and maple.
Weathering and Termite Resistance of Woodflour-Recycled Polypropylene Composites in Tropical Region
Febrianto, Fauzi ; , Indonesia ; Sulaeman, Rudianda ; Karina, Myrtha ; Ashaari, Zaidon ; Had, Yusuf Sudo ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 88~97
Wood flour (WF)-recycled polypropylene (RPP) composites composed of 50% WF of Eucalyptus deglupta Blume species, 50% RPP, various contents of maleic anhydride (MAH) modifier (0; 1; 2; 5; 5; 7.5; and lo%), and 15% dicumyl peroxide (DCP) initiator (based on MAH weight) were subjected to weather for 1 year and subterranean termite (Coptotermes cuwignathus HOLMGREN) and dry wood termite (Cryptotermes cynocephalus LIGHT) for 3 and 4 weeks, respectively. WF-RPP composites with 2.5% MA modifier had tensile strength, breaking elongation and Young's modulus about 2.2, 2.3, and 1.2 times, respectively higher compared to MAH-free composites. The WF-RPP composites with or without MAH modifier had 5.5 times higher resistance to weather compared to RPP film alone. The color of the WF-RPP composites with or without MAH modifier became lighter after exposures to the weather. The WF-RPP composites with or without MAH modifier are resistant to subterranean termite Coptotermes curvignathus HOLMGREN and dry wood termite C~yptote~mecsy nocephalus LIGHT under the experimental condition adopted.
Evaluation of Diffusibility of Boron in Wood under Water Leaching Conditions
Na, Jong-Beom ; Kim, Gyu-Hyeok ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 98~103
Radial and tangential diffusion coefficients of boron in wood under water leachlng conditions were determined from the change of concentration profiles of boron. Ebmer's solution was used to obtain variable diffusion coefficients of boron because it has been known to be the only method to determine variable diffusion coefficients with no cumbersome assumption. The values of diffusion coefficients were between 0.18 X 10.~c m2/sec and 25.6 Y 10.~c m2/sec. They increased with the increase of sample thicknesses, and decreased with the increase of leaching times. There was a region where Egner' s method was not valid. However, Egner' s solution illustrates a convenient way to evaluate difhsion characteristics of boron from wood under water leaching conditions. The difhsion coefficients at wood surface may be regarded as leaching coefficients.
Why are Aspen Extractives More Resistant in Kraft Pulping Than Pine Extractives?
Sin, Su-Jeong ; An, Se-Hui ;
Journal of the Korean Wood Science and Technology, volume 34, issue 5, 2006, Pages 104~110
We investigated why aspen extractives are more resistant in kraft pulping than pine extractives. Residual extractives content in aspen kraft pulps were 0.5- 1.1% compared with 0.1 -0.2% in pine pulps. This different response arises fi-om the different composition of extractives in wood chips. Resin acids in pine were almost completely removed in kraft pulping but those are not existence in aspen. Slower saponification of aspen steryl esters resulted from different chemical structure of aspen steryl esters. Main sterols in aspen steryl esters were 24-methyl cyclolanostenol which was highly resistant to alkaline hydrolysis with its characteristic steric hindrance. Sterols in aspen were not well removed in kraft pulping. The relative composition of sterol in aspen kraft pulps was increased with increasing pulping time. The presence of fatty acids in aspen kraft pulps is considered to unusual. Fatty acids in alkaline are supposed to be well ionized and removed well in the washing stage. Nevertheless, there were significant amount of fatty acids remaining in aspen kraft pulps.