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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 39, Issue 6 - Nov 2011
Volume 39, Issue 5 - Sep 2011
Volume 39, Issue 4 - Jul 2011
Volume 39, Issue 3 - May 2011
Volume 39, Issue 2 - Mar 2011
Volume 39, Issue 1 - Jan 2011
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The Characteristics of Ultrasonic Wave Transmitted Through Drying Wood
Kang, Ho-Yang ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 117~124
DOI : 10.5658/WOOD.2011.39.2.117
The possibility of using the properties of an ultrasonic wave as a means for monitoring the moisture content of a board during drying was investigated. The ultrasonic wave signals are influenced by moisture content and other factors such as temperature, moisture gradient and coupling area. The effect of temperature was examined by measuring the transit times, amplitudes and velocities of ultrasonic waves transmitted through air, a metal bar and a board at various temperatures. The effect of a moisture gradient was studied using a model specimen composing five wood pieces of various moisture contents. The velocity and amplitude of the ultrasonic waves transmitted through air increase with temperature, while those through a metal bar and a board decrease. It was confirmed that the temperature effect is partially attributed to the change of transducer's properties. The effect of a moisture gradient on the velocity of an ultrasonic wave varies with the average moisture content of a board. As the dimension of the end face of a board increases the velocity of an ultrasonic wave increases and low frequency components more dominates than high frequency components. The transit times of ultrasonic waves transmitted through a board during kiln drying reflect the temperature steps in the drying schedule and the transducer temperatures.
Characteristics of the Radio-Frequency/Vacuum Drying of Heavy Timbers for Post and Beam of Korean Style Housings Part I : For Japanese larch round logs with 150 mm and 210 mm in diameter and 2,500 mm in length
Lee, Nam-Ho ; Zhao, Xue-Feng ; Shin, Ik-Hyun ; Park, Moon-Jae ; Park, Jung-Hwan ; Park, Joo-Saeng ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 125~131
DOI : 10.5658/WOOD.2011.39.2.125
The characteristics of radio-frequency/vacuum drying Japanese larch boxed heart round logs with 150 mm and 210 mm in diameter and 2,500 mm in length, subjected to compressive loading, after the pretreatment of kerf were investigated. The results of this study were as the follows: The drying time of about 120 hours~130 hours was needed from green to about 15 percent of moisture content. The gradient of final moisture content for all specimens was very gentle in both longitudinal and transverse directions owing to dielectric heating. The surface checks seriously occurred although the occurrence extent of surface check for the kerfed specimens was slight compared with that for the control specimens because drying stress was relieved by kerf. The occurrence of surface checks for the L-specimen was more serious than that for the S-specimen.
Characteristics of the Radio-Frequency/Vacuum Drying of Heavy Timbers for Post and Beam of Korean Style Housings Part II : For Korean red pine heavy timbers with 250 × 250 mm, 300 × 300 mm in cross section and 300 mm in diameter, and 3,600 mm in length
Lee, Nam-Ho ; Zhao, Xue-Feng ; Shin, Ik-Hyun ; Park, Moon-Jae ; Park, Jung-Hwan ; Park, Joo-Saeng ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 132~139
DOI : 10.5658/WOOD.2011.39.2.132
This study examined the characteristics of radio-frequency/vacuum dried Korean red pine (
) heavy timbers with 250
250 mm (S), 300
300 mm (L) in cross section and 300 mm in diameter, and 3,600 mm in length, which were subjected to compressive loading after a kerf pretreatment. The following results were obtained : The drying time was short and the drying rate was high in spite of the large cross section of specimens. The moisture gradient inall specimens was gentle in both longitudinal and transverse directions owing to dielectric heating. The shrinkage of the width in the direction perpendicular to was 21 percent ~ 76 percent of that of the thickness of square timbers in the direction parallel to the mechanical pressure. The casehardening for all specimens was very slight because of significantly reduced ratio of the tangential to radial shrinkage of specimens and kerfing. The surface checks somewhat severely occurred although the occurrence extent of the surface checks on the kerfed specimens was slight compared withthat on the control specimen.
Strength Properties of Wooden Retaining Walls Manufactured with Pinus rigida Miller
Park, Jun-Chul ; Kim, Keon-Ho ; Lee, Dong-Heub ; Son, Dong-Won ; Hong, Soon-Il ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 140~147
DOI : 10.5658/WOOD.2011.39.2.140
The strength properties of wooden retaining wall which was made with pitch pine were evaluated. Wooden retaining wall was made with diameter 90 mm of pitch pine round posts treated with CUAZ-2 (Copper Azole). The length of the front stretcher of the retaining wall was 3,000 mm. The distance between the headers (the notched member) is 1,000 mm in center and is 900 mm in side. There were connections every 2,000 mm because actually the length of stretcher is limited in the retaining wall. The strength test was carried out according to connection type because the section between stretchers can act as a defect. A result of the strength test according to connection type confirms that connection does not act as defect because the strength of retaining wall in single stretcher is similar to that in the section between stretchers. The strength test of the wooden retaining wall was carried out in 5 types according to the condition of the base section. When the upper soil pressure was 9.8 kN/
, the maximum load of the retaining wall fixing the front foundation shows higher values than those of others. But the total deformation is lower in the retaining wall not to fix a base section than in that to fix a base section. It is thought that the retaining wall not to fix a base section shows low value because the deformation is distributed throughout the retaining wall and it is confirmed that the soil pressure affects supporting the structure because the deformation of the retaining wall under low pressure is 3~4 fold higher than those of others. The failure mode of the retaining wall is the overturning type because the high section is deformed. Mostly, the failure mode is the separation of the header in the notched section.
Effect of Thermal Compression Treatment on the Surface Hardness, Vertical Density Propile and Thickness Swelling of Eucalyptus Wood Boards by Hot-pressing
Unsal, Oner ; Candan, Zeki ; Buyuksari, Umit ; Korkut, Suleyman ; Chang, Yoon-Seong ; Yeo, Hwan-Myeong ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 148~155
DOI : 10.5658/WOOD.2011.39.2.148
Thermal treatment techniques are used for modifying wood and wood-based materials to improve dimensional stability and hygroscopicity. This study investigated the effects of press pressure and temperature on density, vertical density profile, thickness swelling and surface hardness of eucalyptus wood boards. The experimental wood boards were prepared from Turkish River Gum (
Dehn.). The surface hardness value increased with increasing press pressure in the treated groups. The application of a higher pressure at the same temperature level increased the amount of swelling of wood. It means that it is not needed for application of higher pressure to enhance the dimensional stability of wood. It is expected that it is possible to produce increased hardness, dimensional stability and durability by application of hot pressing treatment. This research showed that different press pressure and temperature values should be used to improve the performance properties of eucalyptus wood so that the end-use of the wood materials could be expanded.
Bonding Performance of Glulam Reinforced with Textile Type of Glass- and Aramid-Fiber, GFRP and CFRP
Kim, Keon-Ho ; Hong, Soon-Il ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 156~162
DOI : 10.5658/WOOD.2011.39.2.156
To evaluate the bonding performance of reinforced glulam, the textile type of glass fiber and aramid fiber, and the sheet type of glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) were used as reinforcements. The reinforced glulam was manufactured by inserting reinforcement between the outmost and middle lamination of 5ply glulam. The types of adhesives used in this study were polyvinyl acetate resins (MPU500H, and MPU600H), polyurethane resin and resorcinol resin. The block shear strengths of the textile type in glass fiber reinforced glulam using MPU500H and resorcinol resin were higher than 7.1 N/
, and these glulams passed the wood failure requirement of Korean standards (KS). In case of the sheet types, GFRP reinforced glulams using MPU500H, polyurethane resin and resorcinol resin, and CFRP reinforced glulams using MPU500H and polyurethane resin passed the requirement of KS. The textile type of glass fiber reinforced glulam using resorcinol resin after water and boiling water soaking passed the delamination requirement of KS. The only GFRP reinforced glulam using MPU500H after water soaking passed the delamination requirement of KS. We conclude that the bonding properties of adhesive according to reinforcements are one of the prime factors to determine the bonding performance of the reinforced glulam.
Feasibility of Ultrasonic Log Sorting in Manufacturing Structural Lamination from Japanese Cedar Logs
Oh, Jung-Kwon ; Yeo, Hwan-Myeong ; Choi, In-Gyu ; Lee, Jun-Jae ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 163~171
DOI : 10.5658/WOOD.2011.39.2.163
Because Japanese cedar shows lower mechanical performance, glued-laminated timber (glulam) can be a better way to utilize Japanese cedar for structural purpose. However, low yield of higher grade lamination from log makes it difficult to design structural glulam. This study was aimed to increase the yield of higher grade lamination and provide higher efficiency of manufacturing structural lamination by ultrasonic log sorting technology. Logs were sorted by an existing log grading rule regulated by Korea Forest Research Institute (KFRI). It was found that the KFRI log grading rule contributed to finding better logs in viewpoint of the volumetric yield and it can reduce the number of rejected lumber by visual grading. However, it could not identify better logs to produce higher-grade products. To find an appropriate log-sorting-method for structural products, log diameter and ultrasonic time of flight (TOF) for the log were considered as factors to affect mechanical performance of resulting products. However, it was found that influence of log diameter on mechanical performance of resulting products was very small. The TOF showed a possibility to sort logs by mechanical performance of resulting products even though a coefficient of correlation was not strong (R = 0.6). In a case study, the log selection based on the ultrasonic TOF of the log increased the yield of the outermost tension lamination (E8 or better grade, KS F 3021) from 2.6% to 12.5% and reduced LTE5 (lower than E5 grade) lamination from 43.6% to 10.3%, compared with the existing KFRI log grading rule.
Structural Performance of Finger-Jointed Lumber with Different Joint Configurations
Lee, Sang-Joon ; Eom, Chang-Deuk ; Kim, Kwang-Mo ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 172~178
DOI : 10.5658/WOOD.2011.39.2.172
Three different finger-jointed lumbers which have different geometric features and adhesives were manufactured and studied in this study. Larch and pitch pine lumbers with and without preservative treatment were used. Bending MOE was measured as the preliminary investigation for grouping the specimen. After the finger, bending MOE of two wood species without preservative treatment shows over 97% property of the control group. The tensile modulus also shows almost same property after the finger joint. And it is found out that the preservative treatment induce little effect on bending and tensile MOE. Based on this result, high performance of examined finger-jointed lumber can be found out. However, tensile strength decreased around 20% which would be induced by the crack along the root of the finger which is formed near the edge during manufacturing stage. And finger-jointed lumber with preservative treatment even shows higher decrement of the tensile strength with higher wooden part failure mode.
Influence of Hydrolytic Degradation on the Morphology of Cured Urea-Formaldehyde Resins of Different Formaldehyde/Urea Mole Ratios
Park, Byung-Dae ; Jeong, Ho-Won ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 179~186
DOI : 10.5658/WOOD.2011.39.2.179
In an effort to understand the hydrolytic degradation process of cured urea-formaldehyde (UF) resins responsible for the formaldehyde emission of wood-based composite panels, this study analyzed the influence of acid hydrolysis on the morphology of cured UF resins with different formaldehyde/urea (F/U) mole ratios such as 1.6, 1.4, 1.2 and 1.0. Field emission-scanning electron microscopy (FE-SEM) was employed to observe both exterior and fracture surfaces on thin films of cured UF resins before and after the etching with hydrochloric acid as a simulation of the hydrolytic degradation process. FE-SEM images showed that the exterior surface of cured UF resin with the F/U mole ratio of 1.0 had spherical structures after the acid hydrolysis while the other cured UF resins were not the case. However, the fracture surface observation showed that all the samples possessed spherical structures in the cured state of UF resins although their occurrence and size decreased as the F/U mole ratio increased. For the first time, we found the spherical structures in cured UF resins of higher F/U mole ratio of 1.4. After the acid hydrolysis, the spherical structures became a much predominant at the fracture surface. These results indicated that the spherical structures in cured UF resinswere much more resistant to the hydrolytic degradation by the acid than amorphous region.
Effects of Dilute Acid Pretreatment on Enzyme Adsorption and Surface Morphology of Liriodendron tulipifera
Min, Byeong-Cheol ; Koo, Bon-Wook ; Gwak, Ki-Seob ; Yeo, Hwan-Myeong ; Choi, Joon-Weon ; Choi, In-Gyu ;
Journal of the Korean Wood Science and Technology, volume 39, issue 2, 2011, Pages 187~195
DOI : 10.5658/WOOD.2011.39.2.187
In this study, dilute acid pretreatment of
was performed for enzymatic hydrolysis. As the pretreatment temperature was increased, enzymatic hydrolysis and enzyme adsorption yield also increased. The highest enzymatic hydrolysis yield was 57% (g/g) and enzyme adsorption was 44% (g/g). Enzymatic hydrolysis yield was determined with weight loss of pretreated biomass by enzyme, and enzyme adsorption was a percentage of enzyme weight attaching on pretreated biomass compared with input enzyme weight. When
was pretreated with 1% sulfuric acid at
for 5 min., hemicellulose was significantly removed in pretreatment, but the lignin contents were constant. Other changes in surface morphology were detected on biomass pretreated at
by a field emission scanning electron microscope (FESEM). A large number of spherical shapes known as lignin droplets were observed over the entire biomass surface after pretreatment. Hemicellulose removal and morphological changes improved enzyme accessibility to cellulose by increasing cellulose exposure to enzyme. It is thus evidence that enzyme adsorption is a significant factor to understand pretreatment effectiveness.