The Korean Society of Wood Science & Technology

DOI: JKWST Vol.47(No.4) 1-1, 2019

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The Korean Society of Wood Science & Technology

DOI: JKWST Vol.47(No.4) 2-2, 2019

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김현빈 Hyunbin Kim , 여환명 Hwanmyeong Yeo , Hyunwoo Chung , Yonggun Park , Hyunbin Kim , 양상윤 Sang-yun Yang , 박세영 Se-yeong Park , 권오경 Ohkyung Kwon , 이형구 Hyung Gu Lee

DOI:10.5658/WOOD.2019.47.4.385 JKWST Vol.47(No.4) 385-392, 2019

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In our previous study, we investigated the use of ensemble models based on LeNet and MiniVGGNet to classify the images of transverse and longitudinal surfaces of five Korean softwoods (cedar, cypress, Korean pine, Korean red pine, and larch). It had accomplished an average F1 score of more than 98%; the classification performance of the longitudinal surface image was still less than that of the transverse surface image. In this study, ensemble methods of two different convolutional neural network models (LeNet3 for smartphone camera images and NIRNet for NIR spectra) were applied to lumber species classification. Experimentally, the best classification performance was obtained by the averaging ensemble method of LeNet3 and NIRNet. The average F1 scores of the individual LeNet3 model and the individual NIRNet model were 91.98% and 85.94%, respectively. By the averaging ensemble method of LeNet3 and NIRNet, an average F1 score was increased to 95.31%.

Ji-su Kim , Ji Young Jung , Si Young Ha , Jae-kyung Yang

DOI:10.5658/WOOD.2019.47.4.393 JKWST Vol.47(No.4) 393-407, 2019

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In this study, we prepared lignocellulosic artificial soil that contains Bacillus subtilis (peat moss/perlite/ steam-exploded oak wood/microbial culture = 3:1:3:3, w/w/w/w) for use in the restoration of damaged soil areas. The prepared lignocellulosic artificial soil was mixed with soil at ratios of 0%, 25%, 50%, 75%, and 100%. These mixed soils were then applied to fields, and the resultant physicochemical properties and their effects on the plant growth of Lespedeza cyrtobotrya were observed. The mixture of the prepared artificial soils (mixed at ratios of 25%-100%) with soil had a bulk densities of < 0.04 g/cm³, porosities of >85%, pH values between 4.3 and 4.7, electrical conductivities of <0.5 dS/m, C/N ratios between 15.0 and 26.5, organic matter content between 23.6% and 43.2%, and bacterial densities between 157 × 10⁶ and 624 × 10⁶ CFU/g. In addition, the prepared artificial soils mixed with soil at ratios of 25%-50% exhibited higher plant growth rates for L. cyrtobotrya compared with the control. Overall, we identified positive correlations between the plant growth of L. cyrtobotrya and soil bulk density, porosity, water-holding capacity, C/N ratio, organic matter, and bacterial densities.

Cemal Zcan , Mustafa Korkmaz

DOI:10.5658/WOOD.2019.47.4.408 JKWST Vol.47(No.4) 408-417, 2019

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Non-destructive test techniques are becoming increasingly important for assessment and maintenance. These techniques are very useful for assessment of materials such as wood, whose performance can vary considerably depending on the conditions of use. It is possible to estimate some mechanical properties of a material by determining the movement of energy through the material with the help of these techniques. In this study, it was investigated whether the wood material could be tested nondestructively by the heat energy produced by a source. The correlations between the thermal conductivity and mechanical properties of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea L.) woods were investigated. The thermal conductivity (TC), density, modulus of rupture (MOR), compression strength (CS), and modulus of elasticity (MOE) values of samples were measured according to the related standards and these values were correlated with each other. The linear and multiple regression tests were employed to determine the correlation between thermal conductivity and mechanical properties. The results showed that there is a very strong correlation between thermal conductivity and both density and MOR values. However, the correlations between TC and both MOE and CS were moderate. The results of this study suggest that the thermal conductivity value can be used to estimate the density and some mechanical properties of wood.

Andi Detti Yunianti , Kidung Tirtayasa , Suhasman , Ira Taskirawati , Agussalim , Musrizal Muin

DOI:10.5658/WOOD.2019.47.4.418 JKWST Vol.47(No.4) 418-424, 2019

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Densification is a process for improving the strength properties of wood from the felling of young trees, which is a common harvest practice in community forests. A series of experiments was conducted to refine the process with particular regard to the determination of suitable pretreatment and treatment conditions. Samples of pine and gmelina measuring 23 cm (L) × 20 cm (W) × 2 cm (T) underwent pretreatment through immersion in a 1:1 CH₃COOH-H₂O₂ solution at concentrations of 15%, 20%, and 30%. Samples pretreated with the 20% solution showed the greatest improvement in strength; further experiments were conducted to determine the optimum treatment conditions in terms of temperature and duration following immersion. Test samples with the same dimensions as those in the pretreatment experiment were soaked in a 1:1 20% CH₃COOH-H₂O₂ solution and warmed in a water bath. The test samples were then individually hot pressed to the target thickness, which was 30% less than the original thickness and held at 150°C or 170°C for 15 or 30 minutes. The treated samples were cut for an analysis of their density, recovery of set, and bending strength. Pine and gmelina exhibited the best characteristics after treatment at 150°C for 30 and 15 minutes, respectively. The results suggest that the modified densification process had increased the bending strength of the wood, but the temperature and duration of treatment must be carefully considered for different wood species.

Chun-won Kang , Eun-suk Jang , Sang-sik Jang , Ho-yang Kang , Seog-goo Kang , Se-chang Oh

DOI:10.5658/WOOD.2019.47.4.425 JKWST Vol.47(No.4) 425-441, 2019

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In this study, sound absorption capability and sound transmission loss of several kinds of target densities and thickness for six species of wood bark particle were estimated by the transfer function and transfer matrix methods. Resultantly, the mean sound absorption coefficient of a 100-mm thick Hinoki wood bark particle mat was 0.90 in the frequency range of 100-6400 Hz, whereas the mean sound absorption rate of a 50-mm thick Hinoki wood bark particle mat was 0.84 in the same frequency range. Particularly, at a thickness of 100 mm, it reached almost up to 100% in the frequency range of 1 KHz. The sound transmission losses of 100-mm thick Hinoki wood bark particle mat with a target density of 0.16 at 500 and 1000 Hz were 15.30 and 15.73 dB, respectively. When a 10-mm thick plywood was attached to the back of the wood particle mat, the sound transmission losses was increased by 20-30 dB. Wood bark can be used as an acoustical material owing to its high sound absorption rate and transmission loss.

Kwang Ho Kim , Jae-young Kim , Chang Soo Kim , Joon Weon Choi

DOI:10.5658/WOOD.2019.47.4.442 JKWST Vol.47(No.4) 442-450, 2019

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Despite its potential as a renewable source for fuels and chemicals, lignin valorization still faces technical challenges in many aspects. Overcoming such challenges associated with the chemical recalcitrance of lignin can provide many opportunities to innovate existing and emerging biorefineries. In this work, we leveraged a biomass genetic engineering technology to produce phenolic aldehyde-rich lignin structure via downregulation of cinnamyl alcohol dehydrogenase (CAD). The structurally altered lignin obtained from the Arabidopsis thaliana CAD mutant was pyrolyzed to understand the effect of structural alteration on thermal behavior of lignin. The pyrolysis was conducted at 400 and 500 °C using an analytical pyrolyzer connected with GC/MS and the products were systematically analyzed. The results indicate that aldehyde-rich lignin undergoes fragmentation reaction during pyrolysis forming a considerable amount of C6 units. Also, it was speculated that highly reactive phenolic aldehydes facilitate secondary repolymerization reaction as described by the lower yield of overall phenolic compounds compared to wild type (WT) lignin. Quantum mechanical calculation clearly shows the higher electrophilicity of transgenic lignin than that of WT, which could promote both fragmentation and recondensation reactions. This work provides mechanistic insights toward biomass genetic engineering and its application to the pyrolysis allowing to establish sustainable biorefinery in the future.

Wa Ode Muliastuty Arsyad , Efrida Basri , Djeni Hendra , Deazy Rachmi Trisatya

DOI:10.5658/WOOD.2019.47.4.451 JKWST Vol.47(No.4) 451-458, 2019

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Jabon (Anthocephalus cadamba Miq.) is a fast-growing species that exhibits a lower natural resistance than that exhibited by the timber sourced from natural forests. Jabon’s resistance to termite attack can be improved by impregnating its wood structure with poisonous organic materials. This study examined jabon’s resistance to termite attack when impregnated with wood vinegar and an animal adhesive. The wood specimens were impregnated using sengon wood vinegar and an animal adhesive (8% and 10%, respectively) using a vacuum pressure machine. The specimens were tested for their resistance to subterranean and dry-wood termites according to Indonesian National Standard (SNI 7207-2014). The results denoted that jabon impregnated with wood vinegar and an animal adhesive concentration of at least 8% with the addition of 4% borate was effective to resist termite attacks. The impregnated jabon exhibited a lower weight loss and higher termite mortality when compared with those exhibited by the control specimens. Thus, the resistance class improved from class IV to class I.

Asep Hidayat , Maman Turjaman , Sarah Asih Faulina , Fadel Ridwan , Aryanto , Najmulah , Tun Tedja Irawadi , Apri Heri Iswanto

DOI:10.5658/WOOD.2019.47.4.459 JKWST Vol.47(No.4) 459-471, 2019

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Several species of Aquilaria and Gyrinops are native to Indonesia and well known as agarwood-producing trees with a high economic value. Their bioactive compounds have a wide spectrum of uses, such as in medicine and cosmetics. These genera have undergone extensive search for novel bioactive compounds. The purpose of this study was to isolate, identify, and characterize the endophytic fungi community associated with Aquilaria malaccensis, A. microcarpa, Gyrinops versteegii, and A. crassna trees and investigate their bioactive properties as antioxidant agents and antagonists. A total of 50 fungi were successfully isolated from different tissues of the four species of agarwood-producing trees. Two isolates exhibited strong antioxidant activity, namely, Apodus oryzae (R2MC3A, IC₅₀ 60.92 mg/mL) and Diaporthe sp. (P1DS1[C], IC₅₀ 76.65 mg/mL). Two isolates, Pestalotiopsis theae (P3BS3[B]) and Curvularia sp. (P2CD3A), showed >75% antifungal activity against pathogenic Fusarium solani. The results revealed that endophytic fungi associated with the studied agarwood-producing trees had potential antioxidant and antifungal activities for further applications in biotechnology.

Young-rok Seo , Birm-june Kim , Sun-young Lee

DOI:10.5658/WOOD.2019.47.4.472 JKWST Vol.47(No.4) 472-485, 2019

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When wood plastic composites (WPCs) have been used for a certain period of time, they become waste materials and should be recycled to reduce their environmental impact. Waste WPCs can be transformed into reinforced composites, in which fillers are used to improve their performance. In this study, recycled WPCs were prepared using different proportions of waste WPCs, nanoclay, and glass fiber. The effects of nanoclay and glass fiber on the microstructural, mechanical, thermal, and water absorption properties of the recycled WPCs were investigated. X-ray diffraction showed that the nanoclay intercalates in the WPCs. Additionally, scanning electron micrographs revealed that the glass fiber is adequately dispersed. According to the analysis of mechanical properties, the simultaneous incorporation of nanoclay and glass fiber improved both tensile and flexural strengths. However, as the amount of fillers increases, their dispersion becomes limited and the tensile and flexural modulus were not further improved. The synergistic effect of nanoclay and glass fiber in recycled WPCs enhanced the thermal stability and crystallinity (X_c). Also, the presence of nanoclay improved the water absorption properties. The results suggested that recycled WPCs reinforced with nanoclay and glass fiber improved the deteriorated performance, showing the potential of recycled waste WPCs.

Hyung Won Lee , Hanseob Jeong , Young-min Ju , Won-jae Youe , Jaejung Lee , Soo Min Lee

DOI:10.5658/WOOD.2019.47.4.486 JKWST Vol.47(No.4) 486-497, 2019

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The non-isothermal and isothermal pyrolysis properties of H lignin and P lignin extracted from different biorefinery processes (such as supercritical water hydrolysis and fast pyrolysis) were studied using thermogravimetry analysis (TGA) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). The lignins were characterized by ultimate/proximate analysis, FT-IR and GPC. Based on the thermogravimetry (TG) and derivative thermogravimetry (DTG) curves, the thermal decomposition stages were obtained and the pyrolysis products were analyzed at each thermal decomposition stage of non-isothermal pyrolysis. The isothermal pyrolysis of lignins was also carried out at 400, 500, and 600 °C to investigate the pyrolysis product distribution at each temperature. In non-isothermal pyrolysis, P lignin recovered from a fast pyrolysis process started to decompose and produced pyrolysis products at a lower temperature than H lignin recovered from a supercritical water hydrolysis process. In isothermal pyrolysis, guaiacyl and syringyl type were the major pyrolysis products at every temperature, while the amounts of p-hydroxyphenyl type and aromatic hydrocarbons increased with the pyrolysis temperature.

Hee-jeong Min , Eun-ji Kim , Seong-whan Shinn , Young-soo Bae

DOI:10.5658/WOOD.2019.47.4.498 JKWST Vol.47(No.4) 498-508, 2019

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This study was carried out to investigate the potential of Korean red pine (Pinus densiflora) inner bark extracts as an antidiabetic agent. The ethyl acetate soluble fraction of the bark extracts was chromatographed on a Sephadex LH-20 column to yield five compounds, which structures were elucidated by NMR spectroscopy. The isolated compounds were (+)-catehin, (-)-epicatechin, taxifolin, taxifolin-3’-O-β -D-(+)-glucose and ñ-courmaric acid. The antidiabetic activity of the different fractions, including the crude extracts and isolated compounds, was evaluated by β -cells insulin secretion and glucose uptake in skeletal muscle cells. The insulin secretion was 128% for taxifolin at 25 μg/mL. However, the other samples had no effect on this test. For the glucose uptake activity assay, 1 μM insulin and 2 mM metformin were used as controls. Both the crude extract and taxifolin showed relatively low activity values, but the other samples yielded glucose uptake values over 260%. ρ -courmaric acid showed the highest uptake (270%). The results confirmed that Korean red pine extracts may be used as a hypoglycemic agent.

Seungheon Yeon , Se-yeong Park , Jong-hwa Kim , Jong-chan Kim , Sang-yun Yang , Hwanmyeong Yeo , Ohkyung Kwon , In-gyu Cho

DOI:10.5658/WOOD.2019.47.4.509 JKWST Vol.47(No.4) 509-518, 2019

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This study analyzed the effect of organic solvent extractives on the classification of wood species via near-infrared spectroscopy (NIR). In our previous research, five species of Korean softwood were classified into three groups (i.e., Cryptomeria japonica (cedar)/Chamaecyparis obtuse (cypress), Pinus densiflora (red pine)/Pinus koraiensis (Korean pine), and Larix kaempferi (Larch)) using an NIR-based principal component analysis method. Similar tendencies of extractive distribution were observed among the three groups in that study. Therefore, in this study, we qualitatively analyzed extractives extracted by an organic solvent and analyzed the NIR spectra in terms of the extractives’ chemical structure and band assignment to determine their effect in more detail. Cedar/cypress showed a similar NIR spectra patterns by removing the extractives at 1695, 1724, and 2291 nm. D-pinitol, which was detected in cedar, contributed to that wavelength. Red pine/Korean pine showed spectra changes at 1616, 1695, 1681, 1705, 1724, 1731, 1765, 1780, and 2300 nm. Diterpenoids and fatty acid, which have a carboxylic group and an aliphatic double bond, contributed to that wavelength. Larch showed a catechin peak in gas chromatography and mass spectroscopy analysis, but it exhibited very small NIR spectra changes. The aromatic bond in larch seemed to have low sensitivity because of the 1st overtone of the O-H bond of the sawdust cellulose. The three groups sorted via NIR spectroscopy in the previous research showed quite different compositions of extractives, in accordance with the NIR band assignment. Thus, organic solvent extractives are expected to affect the classification of wood species using NIR spectroscopy.

Sena Maulana , Yuarsa Gumelar , Adesna Fatrawana , Muhammad Iqbal Maulana , Wahyu Hidayat , Ihak Sumardi , Nyoman Jaya Wistara , Seung Hwan Lee , Nam Hun Kim , Fauzi Febrianto

DOI:10.5658/WOOD.2019.47.4.519 JKWST Vol.47(No.4) 519-532, 2019

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The objectives of this study were to evaluate the effects of shelling ratio and resin content on the properties of bamboo oriented strand board (BOSB) from betung (Dendrocalamus asper) and to determine the correlation between the results of dynamic and static bending tests. Strands were steam-treated at 126 ºC for 1 h under 0.14 MPa pressure and followed by washing with 1% NaOH solution. Three-layer BOSB with the core layer perpendicular to the surface was formed with shelling ratios (face:core ratio) of 30:70; 40:60; 50:50; 60:40 and binded with 7% and 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of BOSB was conducted in accordance with the JIS A 5908:2003 standard and the results were compared with CSA 0437.0 standard for commercial OSB (Grade O-1). Non-destructive testing was conducted using Metriguard Model 239A Stress Wave Timer which has a wave propagation time from 1 to 9,999 μs and a resolution of 1 μs. BOSB with 8% resin content showed better physical and mechanical properties than those with 7% resin content. The increase of the face layer ratio improved the strength of BOSB in parallel direction to the grain. The results suggested that shelling ratio of 50:50 could be used as a simple way to reduce PF resin requirements from 8% to 7% and to meet the requirements of CSA 0437.0 standard. The results of non-destructive and destructive tests showed a strong correlation, suggesting that non-destructive test can be used to estimate the bending properties of BOSB.

Sang Sik Jang , Hyoung Woo Lee

DOI:10.5658/WOOD.2019.47.4.533 JKWST Vol.47(No.4) 533-542, 2019

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As energy costs increase, more people has become interested on energy efficiency and savings in residential buildings. The two main subjects related to energy in residential buildings are insulation and condensation. There are two approaches to prevent condensation; increasing air tightness and maintaining the temperature inside of the wall structure over the dew point, which is in turn related to insulation. Even though the Korean government has highlighted the importance of energy efficiency for residential housings, and in spite of the customers’ demands, the timber construction industry is still using conventional light-frame construction without even trying to improve energy efficiency. In this study, various types and combinations of wall structures were tested under cold outdoor and warm indoor temperatures to analyse the temperature gradients and to determine the possible sites of condensation in the wall structures. In addition to the experimental tests, three theoretical models were developed and their estimations of temperature change through the wall structure were compared with the actual measurements to evaluate accuracy of the models. The results of the three models agree relatively well with the experimental values, indicating that they can be used to estimate temperature changes in wall structures. The theoretical analysis of different insulation layers’ combinations show that condensation may occur within the mid-layer in the conventional light-frame wall structures for any combination of inner-, mid-, and outer-layers of insulation. Therefore, it can be concluded that the addition of an inner and outer insulation layer or increasing the thickness of insulation may not be adequate to prevent condensation in the wall structure without preventing penetration of warm moist air into the wall structure.

The Korean Society of Wood Science & Technology

DOI: JKWST Vol.47(No.4) 543-544, 2019

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The Korean Society of Wood Science & Technology

DOI: JKWST Vol.47(No.4) 545-545, 2019

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The Korean Society of Wood Science & Technology

DOI: JKWST Vol.47(No.4) 546-546, 2019

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