• Journal of the Korean Wood Science and Technology
• /
• v.24 no.3
• /
• pp.18-27
• /
• 1996

The feasibility of using stress-wave technique in the transverse direction for the assessment of early stages of decay was investigated using compression test specimens having different annual ring orientations subjected to decay by Tyromyces palustris for various time intervals. Decay detection, quantitative assessment of decay, and the prediction of residual strength of decayed wood with less than five percent weight loss can be feasible using stress-wave parameters (wave velocity, wave impedance, and stress-wave elasticity) and their percent reduction due to decay, measured by stress-wave technique in the transverse direction. The use of stress-wave technique in the transverse direction for the application of this technique to structural members in service is desirable, when considering the easiness of attachment of accelerometers of stress-wave measuring device on the surface of members and also accurate detection of localized decayed areas. In stress-wave technique in the transverse direction, stress-wave parameters measured were different according to the angles between wave propagation path and annual ring, due to the anisotropy of wood structure. Therefore, it is recommended to use percent reduction in stress-wave parameters instead of stress-wave parameters. This evaluation method using percent reduction in stress-wave parameters is ideal when it is impossible to observe annual ring orientation on the transverse surface of wood.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.35 no.12
• /
• pp.1477-1485
• /
• 2011

Dyeability and colorfastness of the blended knits of cotton/rayon (40/60; C/R) and wool/tencel (10/90; W/T) are examined using the natural dyestuff ($Pinux^{TM}$) manufactured from Pinus radiata pine bark extract. In addition, pre-treatments (such as bleaching, mercerization and cationization) are performed to improve dyeability and colorfastness. The $Pinux^{TM}$ powder dyestuffs produced by Pinux Co., Ltd. are used as dyestuffs and their properties are examined for dyeing concentration (0.5-2% (owb)), dyeing time (30-120 minutes) and dyeing temperature (30-$90^{\circ}C$). Dyeability is evaluated with K/S value at 400nm, which is the maximum absorption wavelength for $Pinux^{TM}$. The results show the dyeability of W/T sample containing protein fiber with $Pinux^{TM}$ is superior to all cellulose fiber C/R. A concentration of dyestuff greater than 1.5% (owb), dyeing time 120 minutes and dyeing temperature of $90^{\circ}C$ are the most optimized conditions. It shows that the dyeability of C/R and W/T samples are high in the condition of an acid-dyeing bath and that dyeability highly declined in alkaline bath due to the instability of the proanthocyanidin pigment. After analyzing the effect of bleaching, mercerizing and cationizing (as pre-treatments on dyeability) it was concluded that the dyeability of the C/R sample was enhanced by mercerization but no significant effect by cationization. However, the simultaneous treatment of cationizing and dyeing resulted in far improved dyeability compared to dyeing after cationizing pre-treatment. As for the W/T sample, the effect of cationization was more prominent than the C/R sample. Colorfastness to color changes in the control W/T sample was higher than that of C/R's level 1-2, and it increased to Level 2 when bleaching pre-treatment was given and when a simultaneous cationizing treatment was adopted to the dyeing process. Colorfastness to light in W/T control sample resulted in Level 3 and further increased to an excellent Level of 4 with bleaching and simultaneous cationizing during dyeing process.

• Journal of the Korean Wood Science and Technology
• /
• v.32 no.4
• /
• pp.36-45
• /
• 2004

The plywood for concrete form is regarded as a laminate plate composed of orthotropic materials and the flexural analysis is conducted by applying the laminate plate theory, in which the four edges of the plate is assumed to be simply supported and the concentric point lateral load is applied. The results of flexural experiment are compared with the theoretical ones. Theoretically predicted results coincide with experimental ones up to the point of deflection less than 1/4 of plate thickness. In addition, when the plywood is regarded as an isotropic plate for simple analysis, the geometric average of the elastic modulus measured in the direction parallel to the face grain (E₁₁) and perpendicular to the face grain (E₂₂) could be used for the elastic modulus of isotropic plate.

• Journal of the Korean Wood Science and Technology
• /
• v.23 no.3
• /
• pp.16-22
• /
• 1995

The profiles of the heating temperature in three water vat temperatures (55, 66 and 77$^{\circ}C$) and the cooling temperature under the average ambient temperature of 3$^{\circ}C$ in 4 and 10cm depths from surface at the center of veneer bolts length showed similar patterns for Japanese larch (Larix leptolepis). Dahurian larch (Larix gmelinei) and Radiata pine (Pinus radiata). The difference of these core temperatures of 10cm depth from surface varied proportionally with the increase of vat temperatures. The average heating time based on final core temperature of 6$^{\circ}C$ lower than vat temperature required about 14.5 hours in vat temperature of 55$^{\circ}C$ and 13.5 hours in vat temperature of 66and 77$^{\circ}C$. Each internal temperature of 4 and 10cm depths from surface started to decrease from the beginning of cooling and after about two hours.

• Journal of the Korean Wood Science and Technology
• /
• v.25 no.1
• /
• pp.28-36
• /
• 1997

Several thick board and dimension lumbers of Japanese larch(Larix leptolepis), Dahurian larch(Larix gmelini) and radiata pine(Pinus radiata) air-dried in four different seasons to compare air-drying process. Patterns of air-drying curves were influenced by climatological conditions and limber thickness. The initial drying rates of summer were the highest, followed those of fall, spring and winter. The drying times to equilibrium moisture contents for four seasons were nearly the same except for winter. However, the drying time for winter required twice more time than the other seasons. The drying time of dimension lumbers required 1.3 times more than boards. The final moisture contents were lowest during spring, highest during winter and similar between summer and fall.

• Journal of the Korean Wood Science and Technology
• /
• v.37 no.5
• /
• pp.421-425
• /
• 2009

This research investigates the effect of copper retention on copper leaching in wood treated with copper-based preservatives. Radiata pine (Pinus radiata D. Don) sapwood samples were ground in a Wiley mill equipped with a 20-mesh screen. The ground wood was vacuum-treated with various concentrations of alkaline copper quat (ACQ), bis-(N-cyclohexyl-diazeniumdioxy)-copper (CB-HDO), and copper azole (CUAZ). The treated samples were conditioned at $70^{\circ}C$ and 100% RH for 72 hours. The samples were leached by using the distilled water for four weeks, and the copper contents in each sample were measured by X-ray spectroscopy. As expected, the copper leaching was increased with increasing of copper retention. The copper leaching from the ACQ and CB-HDO treated samples were gradually decreased with increasing copper retention: however, the copper losses from the CUAZ treated samples appeared to be proportionally increased with the increase in copper retention in all retention levels tested. The results indicate that at the conditions of the same copper retention ACQ and CB-HDO treated wood have a better leaching resistance compared to CUAZ treated wood.

• Journal of the Korean Wood Science and Technology
• /
• v.25 no.3
• /
• pp.16-23
• /
• 1997

This study was carried out to discuss feasibility of high density polyethylene(HDPE) as a new substitute for the conventional adhesives in plywood manufacture. Plywood was composed of radiata pine(Pinus radiata) and Malas(Homallium feotidium) veneers and bonded by HDPE. Adhesion characteristics and anatomical scanning has been examined through tensile-shear strength test and scanning electron microscopy(SEM). The results are as follows; 1. Optimum loading quantity was 15g/$(30.3{\times}30.3)cm^2$, and tensile-shear strength increased with the increase of loading quantity. 2. Even at the hot pressing time of 1 minute, tensile-shear strength met the value of KS(over the 7.5kgf/$cm^2$), and tensile-shear strength increased with the increase of hot pressing time. 3. Plywood composed of veneer at moisture content of 19.6% showed similar tensile-shear strength to that at air conditioned moisture content of 11.4%. 4. Under the same condition of hot pressing time, tensile-shear strength of plywood bonded by HDPE met the KS value of boil and wet test and proved the same group as phenol formaldehyde adhesive. 5. HDPE films showed mechanical adhesion through penetration into the lathe check and ray of veneer.

• Journal of the Korean Wood Science and Technology
• /
• v.31 no.3
• /
• pp.24-29
• /
• 2003

This research was performed to investigate the diffusivity of borate rods in radiata pine (Pinus radiata D. Don) conditioned to 40 percent moisture content (MC). The deepest penetration of boron were observed in the longitudinal direction, followed by the radial and the tangential directions. The boron loading on the wood face adjacent to the borate rod tended to increase with diffusion time in all directions. To mathematically quantify boron diffusion, the diffusion coefficient of boron was determined using Boltzmann's transformation by assuming that it was a function of concentration only. The values of the longitudinal diffusion coefficients were between 1.3×10^-8 cm²/sec and 9.2×10^-8 cm²/sec. The radial diffusion coefficients were between 1.4×10^-8 cm²/sec and 9.5×10^-8 cm²/sec, and the tangential diffusion coefficients were between 5.2×10^-9 cm²/sec and 1.3×10^-8 cm²/sec. The differences of diffusion coefficients between the longitudinal direction and the radial direction were slight, although their concentration profiles were markedly different. This indicates that the amount of boron loading on the wood face adjacent the borate rod is one of the most important factor for boron penetration in wood with low MC.

• Journal of the Korean Wood Science and Technology
• /
• v.39 no.3
• /
• pp.206-212
• /
• 2011

It was investigated the hardness and dimensional stability of heat-compressed wood by compression temperature and time. The surface hardness of heat-compressed wood increased with increasing compression temperature. The lowest hardness value (5.0 N/$mm^2$) was observed in the temperature $70^{\circ}C$ while the highest value (15.6 N/$mm^2$) was obtained in compression temperature $220^{\circ}C$. Dimensional recovery test results showed that fixation of compression set improved with increasing compression temperature. However, the fixation effects were negligible by press time. Contact angle increased with increasing press temperature and time.

• Journal of the Korean Wood Science and Technology
• /
• v.39 no.3
• /
• pp.238-243
• /
• 2011

This study was estimated the change of color of compressed wood by compression temperature and time. Wood color was measured using a colorimeter and evaluated by the NBS (National Bureau of Standards) unit. As a result, the whiteness decreased with increasing compression temperature. In contrast, redness and yellowness was increased with increasing compression temperature. All of the color difference showed the 'Very Much' by NBS unit. The whiteness decreased with increasing compression time. The redness and yellowness were insignificant effect on compression temperature. In other words, the effect of compression temperature was much greater than compression time in the change of wood color.