• Journal of the Korean Wood Science and Technology
• /
• 제32권6호
• /
• pp.50-56
• /
• 2004

This study was conducted to investigate the performance of sound absorption type-noise barriers manufactured with a combination of wood particles used for particleboard, recycled waste newspaper, and cement. An average density of wood-combined cement board was in the range from 0.83 to 0.96 g/cm³, showing relatively low-density board. Regardless of types of cement bonded board or wooden board, the board with concave holes(凹)-formed surfaces showed greater sound absorption coefficient compared to those of flat surface boards. The board density was not related with those coefficients. Accordingly, it was concluded that concave or deep corrugated surface structure has played an important role in sound absorption for the application of sound absorption type-noise barrier.

• Journal of the Korean Wood Science and Technology
• /
• 제47권1호
• /
• pp.21-32
• /
• 2019

In order to investigate the decay process of wood treated with preservative, waterproofing agent and their compound systems, a full-cell process was applied to impregnate the sapwood of poplar (Populus cathay) at paraffin wax emulsion concentrations of 0.5% and 2.0%, Copper Azole (CA) concentrations of 0.3% and 0.5%, and their four compound systems, respectively. Leaching tests and laboratory decay resistance against the white-rot fungus Corious versicolor (L.) Murrill for treated wood were carried out according to the America Standard E11-06 and China Standard GB/T 13942.1-2009. At certain time intervals during the decay test, samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction technique (XRD) to investigate the time-dependent changes of chemical components and crystalline structure, thus clarifying the decay mechanisms. The results suggested that white-rot fungi degrade hemicellulose and lignin in the wood cell wall first, followed by a simultaneous degradation of polysaccharides and lignin. Besides, CA could not only slower the decomposition of both hemicellulose and lignin, but also reduce the degradation amount of hemicellulose. However, paraffin wax emulsion at high concentration had a negative effect on the impregnation of CA for the compound system treated wood.

• Journal of the Korean Wood Science and Technology
• /
• 제26권1호
• /
• pp.63-69
• /
• 1998

This study was carried out to get some basic information on mechanical properties of Korea Lepidobalanus for rational utilization of wood. Five species of Quercus variabilis, Q. aliena, Q. serrata, Q. mongolica, Q. acutissima belong to Lepidobalanus were investigated in this research. Relationship of anatomical characteristics to compression strength parallel to grain was analyzed using stepwise regression technique. All possible combination of 21 independent variables were regressed on compression strength parallel to grain. The summarized results in this study were as follows: I. In the proportion of wood structural elements, the factors that had the greatest influence on compression strength parallel to grain appeared to be proportion of ray in earlywood in Q. variabilis and Q. acutissima, proportion of wood fiber in latewood in Q. aliena and Q. serrata and proportion of vessel in earlywood in Q. mongolica respectively. 2. In the size of wood element and its structure, the factors that had the greatest influence on compression strength parallel to grain were microfibril angle in Q. variabilis, Q. serrata and Q. mongolica and length of wood fiber in Q. aliena and Q. acutissima.

• Journal of the Korean Wood Science and Technology
• /
• 제30권3호
• /
• pp.1-11
• /
• 2002

This study was conducted to investigate the effects of reaction pH conditions and hardener types on the reactivity, chemical structure and adhesion performance of UF resins. Three different reaction pH conditions, such as traditional alkaline-acid (7.5 → 4.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins which were cured by adding three different hardeners (ammonium chloride, ammonium citrate, and zinc nitrate) to measure adhesion strength. Fourier transform infrared (FT-IR) and carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopies were employed to study chemical structure of the resin prepared under three different reaction pH conditions. Adhesion strength of the resins cured with three different hardeners was determined with lap shear specimens in tension. The gel time of UF resins decreased with an increasing in the amount of both ammonium chloride and ammonium citrate added in the resins. However, the gel time increased for zinc nitrate. Both FT-IR and ¹³C-NMR spectroscopies showed that the strong reaction pH condition produce uronic structures in UF resin, while both alkaline-acid and weak acid conditions produce quite similar chemical species in the resins. The maximum adhesion strength was occurred with the resin prepared under strong acid pH condition. However, this study indicated that the weak acid reaction condition provide a balance between increasing resin reactivity and improving adhesion strength of UF resin. The measurement of formaldehyde emission from the panels bonded with the UF resins prepared is planned for future work.

• Journal of the Korean Wood Science and Technology
• /
• 제49권6호
• /
• pp.658-666
• /
• 2021

A novel flame retardant and antibacterial composite membrane coating for wood surfaces was prepared by adding POSS-based phosphorous nitrogen flame retardant (later referred to as NH₂-POSS) and silver nanoparticles (Ag NPs) to chitosan (CS). The effects of NH₂-POSS content (mass fractions of CS 0%, 0.5%, 1%, 3%, 5%, and 7%) on the structure and properties of the composite membrane coating on wood were investigated. The composite film was prepared by the method of blending and ducting. Contact angle, tensile property and antibacterial effects of the composite film were measured, and infrared spectroscopy was used. The results show that the addition of NH₂-POSS can not only improve the toughness of the membrane, but also the flame retardancy of the membrane, which improves the application of the membrane in wood products. However, with the addition of NH₂-POSS, the transparency of the composite membrane was weakened. The inhibitory effect of the composite membrane on the growth of Escherichia coli was enhanced with the increase in Ag NPs. This research provides a foundation for the application of functional wood.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.1038-1042
• /
• 2007

The factors influencing the floor impact sound insulation include floor finishing materials, shock absorbing floors (slabs included), and ceiling structures. The ceilings of the apartment houses, currently built in Korea, are set up with lower parts of slabs and paper finishing, or with double floors for protecting against floor impact sounds in order to improve the sound insulating performance. The most common the method of ceiling structure construction consists of 'wood boarded frames + Gypsum boards + ceiling papers', which is called the wood boarded frame method. This study aimed to measures and evaluates floor impact sound insulation by which the ceiling space are widened according to suppression system is added in apartment house ceiling structure.

• Journal of the Korean Wood Science and Technology
• /
• 제29권3호
• /
• pp.73-82
• /
• 2001

The ESEM could be used in investigating the fibrous networks developed during handsheet-forming processes with the exception of the stages relating to the actual dispersion of the fibers and the drying of formed sheets. Also the cross-sectional images of swollen fibers were generated with the ESEM but the information given by the images was rarely fresh compared to the CLSM images. The LTSEM was extremely useful in generating images of the microfibrillar structure of a wet fiber with great resolution. However, pretreatment required in the LTSEM chamber was somewhat tedious due to the time consumed in sublimation of ice and sputter coating. For observation of lamellar structure of a hydrated fiber, the LTSEM exhibited greatly detailed structure with high resolution. Finally ESEM and LTSEM should be used in a finite field such as observation of surface morphology in detail.

• Journal of the Korean Wood Science and Technology
• /
• 제42권2호
• /
• pp.183-192
• /
• 2014

For the structure determination of D-(+)-sucrose, which consists of ${\alpha}$-D-(+)-glucose and ${\beta}$-D-(+)-fructose, it was acetylated with acetic anhydride and triethyl amine, pyridine, zinc chloride, and sodium acetate as catalysts. The acetylated D-(+)-sucrose was acid-hydrolyzed using sulfuric acid and sodium chloride in methanolic solution. The structures of the reaction products were determined by $^1H$-NMR and $^{13}C$-NMR spectra. The yield of the acetylation indicated the high value in zinc chloride as 70% in zinc chloride catalyst. The acid-hydrolyzed product of the acetylated D-(+)-sucrose, 2,3,4,6,1',3',4',6'-octa-O-acetyl-D-(+)-sucrose, gave 2,3,4,6-tetra-O-acetyl-${\beta}$-D-(+)-glucose and it suggests that the acetylated D-(+)-sucrose was rearranged through the formation of oxonium ion by mutarotation in the 2,3,4,6-tetra-O-acetyl-${\alpha}$-D-(+)-glucose moiety and through the ring opening in the 1',3',4',6'-tetra-O-acetyl-${\beta}$-D-(+)-fructose moiety.

• Journal of the Korean Wood Science and Technology
• /
• 제45권6호
• /
• pp.746-752
• /
• 2017

Cross-laminated timber (CLT) is a relatively new engineered wood for timber construction. It is a great shear wall material. It was known that the shear performance of the CLT wall depends on the performance of connections. In connection, nail or screw has to be installed with a certain distance from the end of the timber. Current building code specifies the distance on the name of end distance. The end distance was decided as a minimum distance not to make splitting or tearing out in lumber or glued laminated timber. As a relatively new engineered wood, the end distance of CLT connection need to be identified because CLT is cross-wisely glued lumber products like plywood. Different from glued laminated timber or lumber, cross layer of CLT may prevent wood from splitting or tearing-out. As a result, the end distance of CLT was expected to be reduced than glued laminated timber. The shorter end distance may let more versatile connector design possible. In this study, prior to developing novel connection for CLT, the end distance of CLT connection was experimentally investigated to identify the end distance limitation. The experiments showed that the end distance can be reduced from 7D to 6D, in case of the tested CLT combination and screw in this study.

• Journal of the Korean Wood Science and Technology
• /
• 제35권6호
• /
• pp.31-42
• /
• 2007

국산 침 활엽수재의 열분해 및 해부학적 특성에 관해 조사하기 위해 침엽수재 3종(소나무, 리기다소나무, 낙엽송) 및 활엽수재 3종(단풍나무, 물푸레나무, 굴참나무)의 화학적 성분분석, TG-DTA (Thermogravimetric Analysis & Differential Thermal Analysis), 메틸렌블루 흡착성능(MBA) 및 SEM 관찰을 하였다. TG-DTA에서 시료는 $1{\ell}/min$로 $N_2$ 가스가 유입되는 조건하에 $10^{\circ}C$/min의 숭온속도로 최대 $10^{\circ}C$까지 탄화되었다. 화학적 성분분석 결과 모든 시료에서 전형적인 목재 주성분의 함량을 나타냈다. TG-DTA 결과, 침엽수재의 탄화수율이 활엽수보다 높았으며 목재 주성분 중 리그닌의 탄화수율이 가장 높았다. 모든 시료가 전형적인 목재 열분해의 TGA, DTG, DTA 곡선을 나타냈지만, 침 활엽수재 간에 몇 가지 차이점이 나타났다. 리그닌의 함량이 열분해에 큰 영향을 미쳤으며, 리그닌의 분자구조에 따라 중량감소와 탄화수율이 크게 달라졌다. 메틸렌블루 흡착성능 시험 결과 침엽수재의 MBA가 활엽수재보다 높았으며 소나무의 MBA가 가장 높았지만, 활성탄이나 백탄보다는 약 23배, 4씩 낮았다. SEM 관찰 결과 탄화 과정에서 전체적인 목재의 구조와 목재 섬유의 섬유구조가 그대로 유지됨을 확인하였다.