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Vol.46 No.5 September 2018
46(5) 1-1, 2018
DOI: JANT Vol.46(No.5) 1-1, 2018
Aims and Scope
46(5) 2-2, 2018
DOI: JANT Vol.46(No.5) 2-2, 2018
Planar (Rolling) Shear Strength of Structural Panels Using 5-point Bending Test
Sei Chang Oh
46(5) 425-436, 2018
DOI: JANT Vol.46(No.5) 425-436, 2018
This study was conducted to evaluate the planar (rolling) shear strength of OSB (oriented strand board) panels and domestic plywood through 5 point bending test method in ASTM D2718 standard. The test specimens were prepared in parallel and perpendicular direction to major axis (along the length of panels) and tested up to failure, and failure modes were also examined. From the test results, rolling shear strength were found to be 1.32 ~ 1.94N/mm2 in parallel to major axis, and 1.46 ~ 1.99N/mm2 in perpendicular to major axis respectively. Little difference was found between parallel and perpendicular direction of rolling shear strength. There were no statistically significant differences in rolling shear strength between Canadian OSB and domestic plywood in the parallel direction, and between Chilean OSB and domestic plywood in the perpendicular direction. The shear failure was observed in all tested OSB panels, whereas shear failure, glue line delamination, and bending combined with shear failure were observed in the domestic plywood.
Physical Characteristics of Korean Red Pines According to Provinces (Goseong, Hongcheon and Bonghwa-gun)
Min-ji Kim , Byung-ro Kim
46(5) 437-448, 2018
DOI: JANT Vol.46(No.5) 437-448, 2018
Physical characteristics of Korean red pine (Pinus densiflora) were investigated with different cultivation locations in Taebaek Mountains as Goseong-gun, Hongcheon-gun and Bonghwa-gun as experimental sites. Moisture content based on air-dried or green (artificial) wood was no significant differences with different cultivation places. Specific gravities of both sapwood and heartwood of red pine from Bonghwa-gun were higher than those from other two sites (Hongcheon-gun or Goseong-gun). Specific gravity of heartwood of red pine from Goseong-gun was higher than it from Hongcheon-gun, but this trend was opposite in case of sapwood. Higher specific gravity of red pine heartwood from Goseong-gun maybe resulted in higher strength than those of other sites. In shrinkage ratio, there was no significant difference among different cultivation places in radial directions, but red pine from Bonghwa-gun was higher than those of other sites in tangential directions. Hygroscopicity was no significant differences with different cultivation places. These results will be helpful information for efficient use of pinewood and good quality of pinewood production for genetical breeding improved.
Current Researches on the Protection of Exterior Wood from Weathering
46(5) 449-470, 2018
DOI: JANT Vol.46(No.5) 449-470, 2018
A review of research trends on wood surface protection for exterior use obtained the following conclusions: It has been reported that inorganic compounds such as chrome and copper used as wood preservatives can protect wood from weathering. It has been shown that precoating with hydrophobic substances such as wax and oil, UV absorbers, and HALS (Hindered Amine Light Stabilizers) enhances weathering resistance on the surface of ACQ-treated wood. Opaque coatings of paint/stains and semitransparent stains on the surface of preservative treated wood can increase the synergistic effects on prevention of weathering deterioration. Also the need for repainting periodically for the protection of the preservative treated wood surface has also been suggested. ZnO or TiO2 of fine particles, metal ions such as Co, Cr, Fe, Mn, Ni and Ti, and UV absorbers such as tris-resorcinol triazine derivatives, triazine and benzotriazole were introduced as additives for preventing UV in the transparent coating on wood. Several reports showed that chemical modification such as methylation, acetylation, or alkylations have made some increases the effects of preventing weathering with the increasing weight gain of chemical formulas. In heat-treated wood, there were various contradictory reports on the resistance of weathering, and there were some other reports emphasizing the necessity of painting with UV resistance, which leads to the necessity of more advanced studies.
Dimensional Stabilization through Heat Treatment of Thermally Compressed Wood of Korean Pine
Jeong Min Lee , Won Hee Lee
46(5) 471-485, 2018
DOI: JANT Vol.46(No.5) 471-485, 2018
Post-heat treatment experiments were carried out for complete dimensional stabilization of thermally compressed wood (Pinus koraiensis). An absorption test was carried out to evaluate the dimensional stability. The specific gravity increased from 0.43 to 0.79 by thermal compression at a compression ratio of 50% thickness. Through the post-heat treatment of compressed wood, the water absorption and thickness swelling decreased with increasing the heat treatment temperature and time. In the case of the thickness recovery rate, when the heat treatment was performed for 24 hours at 120 °C, 140 °C and 160 °C, the thickness recovery was less than 1%. Therefore, it can be confirmed that the method of dimensional stabilization method of the thermal compression wood can be carried out very effectively through post heat treatment process.
Change of Bending Properties of 2×4 Larch Lumber According to Span Length in the Four Point Bending Test
Chul-ki Kim , Kwang-mo Kim , Sang-joon Lee , Moon-jae Park
46(5) 486-496, 2018
DOI: JANT Vol.46(No.5) 486-496, 2018
This study was conducted to confirm an effect of span length on bending properties of larch dimensional lumber in the four point bending test. The size of specimen in this study was 38 (width) × 89 (depth) × 3,600 (length) mm3, and average air-dry density and moisture content of the specimens was 543.5 kg/m3 and 10.5%, respectively. Visually graded No. 1 dimensional lumbers of 248 were divided by two groups to compare modulus of rupture (MOR) and modulus of elasticity (MOE). One group was tested in the four point bending test with span length of 1,650 mm, and other was tested with span length of 3,000 mm. While MOE was not different according to span length in 5% significance level, MOR was different in accordance with span lengths and was in inverse proportion to change of span length. Fifth percentiles of MOR in span length of 1,650 and 3,000 mm were 28.65 and 25.70 MPa, respectively. It was confirmed that the difference between MORs in each case increased as normalized rank increased. This is because of size effect in Weibull weakest link failure theory. Therefore, KS F 2150, in which there is only regulation about span to depth ratio of 15 or more, is needed to be revised to contain a method considering size effect for MOR. From the method, various results of bending test with different size of lumber could be used to determine design value of lumber.
Evaluation of Deterioration of Larix kaempferi Wood Heat-treated by Superheated Steam through Field Decay Test for 12 Months
Yonggun Park , Yeonjung Han , Jun-ho Park , Hyunwoo Chung , Hyunbin Kim , Sang-yun Yang , Yoon-seong Chang , Hwanmyeong Yeo
46(5) 497-510, 2018
DOI: JANT Vol.46(No.5) 497-510, 2018
In this study, the decay resistance of larch wood, which was heat treated by superheated steam, was evaluated by the field decay test. During the field decay test of 12 months, non-treated wood has been severely damaged by termite, however, no visible damage has occurred in the preservative-treated wood and superheated steam heat-treated wood. Results of field decay test showed approximately 5% mass loss of the non-treated wood and the preservative-treated wood, and approximately 1% mass loss of the superheated steam heat-treated wood. After the field decay test for 12 months, the residual amount of preservatives remaining in the preservative-treated wood was lower than that before the field decay test. It was considered that the preservative was partially eluted during the field decay test, and the mass loss of the preservative-treated wood was thought to be similar to that of the non-treated wood. Through this study and additional long-term monitoring test, superheated steam heat treatment can be considered to be an environmental-friendly method to enhance the decay resistance of wood against rot fungi and/or insect without chemical treatment such as preservative injection.
Effects of Heat Treatment on the Characteristics of Royal Paulownia (Paulownia tomentosa (Thunb.) Steud.) Wood Grown in Korea
Yun Ki Kim , Gu Joong Kwon , Ah Ran Kim , Hee Soo Lee
46(5) 511-526, 2018
DOI: JANT Vol.46(No.5) 511-526, 2018
Effects of heat treatment on the characteristics of Royal paulownia (Paulownia tometosa) wood were investigated. The results were compared with those of Suwon silver poplar (Populus tementiglandulosa) and Korean red pine (Pinus densiflora) woods. The wood samples of the three species were treated at 160°C, 180°C, 200°C and 220°C in an electric furnace for 2 hours. The changes of color, density, mass loss, and relative crystallinity were investigated before and after heat treatment. The lightness (L*) decreased rapidly from 200℃ in all species. There were no change in red-green chromaticity(a*) and yellow-blue chromaticity(b*) of Royal paulownia and poplar woods with increasing temperature. Whereas, yellow-blue chromaticity(b*) of Korean red pine wood decreased sharply from 200℃. Royal paulownia wood showed appreciable color change(ΔE*) after heat treatment above 180°C. Poplar and pine woods, however, presented significant color change from 160℃. Color change of the three wood species increased rapidly with increasing temperature. Mass loss of the three wood species by heat treatment was the highest in the Royal paulownia wood and the lowest in the pine wood. Mass loss and relative crystallinity increased and density decreased slightly with increasing temperature. Consequently, it is revealed that Royal paulownia wood showed considerable differences in the temperature of color change, weight loss and change of relative crystallinity compared to the other wood species.
Characteristics of White Charcoal Produced from the Charcoal Kiln for Thermotherapy
Gu Joong Kwon , Ah Ran Kim , Hee Soo Lee , Seung Hwan Lee
46(5) 527-540, 2018
DOI: JANT Vol.46(No.5) 527-540, 2018
In this study, the characteristics of the white charcoal from charcoal kilns made for both charcoal production and thermotherapy and from the traditional charcoal kiln were compared and examined. A charcoal kiln for thermotherapy as a secondary purpose was made to minimize environmental problems such as fine dust and harmful gas generated from sealed charcoal kiln in consideration of comfort and safety. White Charcoal produced from the charcoal kiln for both charcoal production and thermotherapy had higher ash and volatile matter and lower fixed carbon than that from the traditional charcoal kiln. The density of the white charcoal produced from the charcoal kiln for both charcoal production and thermotherapy was slightly higher than that of the traditional one, but the equilibrium moisture content and pH were not significantly different. The calorific value, refinement degree, hardness and anatomical structure were not different between the two. It was concluded that the white charcoal produced from the advanced charcoal kiln for thermotherapy as a secondary purpose meets the quality certification standards of Korea Forest Research Institute.
Journal of the Korean Wood Science and Technology
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