• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.401-408
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• 2021

Supplies of wood chips for fuel tend to increase owing to energy decentralization and new renewable energy policies. This study suggests a technical method that is necessary in order to supply heating energy to rural regions by using wood chips for fuel. Therefore, this study investigates the effects of natural drying methods for eight months by installing a drying facility with natural ventilation capable of loading 10 tons of wood chips, and which derive a natural drying method based on this to meet the quality standards of wood chips for fuel. The study results confirm that it is possible to produce wood chips for high-quality fuel with water content at 20% or less after around 90 days of drying, provided that a drying facility with natural ventilation is equipped with materials that can be procured easily in rural regions. It is also possible to block the proliferation and fermentation of molds that affect the quality of wood chips, provided that intake and exhaust systems adhering to standards are equipped.

• Journal of the Korean Wood Science and Technology
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• v.32 no.1
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• pp.45-51
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• 2004

Combined microwave-convective drying of 2.4mm-thick radiata pine veneer grown in New Zealand was conducted to investigate drying characteristics. The veneers could be dried from 160% to 0% moisture content in 7.5 min by microwave drying combined with hot-air of 100℃. This drying rate is about three times higher than that of conventional convective drying with only hot air of 100℃. However there remained charred spots when too high microwave power was applied. Therefore investigations of the microwave-drying characteristics of veneer of various sizes and species are needed to determine the optimal drying conditions.

• Fire Science and Engineering
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• v.29 no.4
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• pp.49-56
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• 2015

Toxic gases from five types of interior building materials were investigated according to Naval Engineering Standard (NES) 713. The materials were plywood, indoor wall coverings (wood wall plate members and pine wood), reinforced Styrofoam insulation, laminate flooring, and PVC. Specimens were measured using an NES 713 toxicity test apparatus to analyze the hazardous substances in combustion gas from the materials. We used the US Department of Defense standard (MIL-DTL, Military Standard) to calculate the toxicity index of the combustion gas. Emissions of $CO_2$ from all specimens did not exceed the NES 713 limit of 100,000 ppm. The amount of CO gas emissions from reinforced Styrofoam insulation was 6,098 ppm. 25 ppm and 49 ppm of formaldehyde were released from the reinforced Styrofoam insulation and PVC flooring, respectively. These values were less than the limit of 400 ppm. The highest emissions were from $NO_X$ emitted by plywood and were above the limit of 250 ppm. The toxicity index of the specimens were calculated as 5.19 for plywood, 4.13 for PVC flooring, 2.35 for reinforced Styrofoam insulation, 2.34 for laminate flooring, and 1.22 for indoor wall coverings (pine wood). Our research helps us to understand the properties of these five interior materials by analyzing the combustion gas and explaining the toxicity of constituents and the toxicity index. Also, it would be useful for giving fundamentals to guide the safe use of interior materials for applications.

• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.337-345
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• 2013

Log grading rules are essential tools to ensure the quality of logs in distribution structure. The rules should reflect the long experience and accepted usage practice in the market. A gap between the rules and market should be improved based on analysis of log qualities that produced and market demand. In this study more than ten millions logs which were produced by 5 Regional Forest Services in 2010~2011 period, were analyzed in their qualities including diameters and lengths by species. A proposal was driven to improve the current log grading rules in terms of log diameter classes and length. The followings are the summary of this study. Most of domestic softwood logs are belong to small diameter class of 100~160 mm, which imply the diameter classes of current log grading rules are immoderate. Distributions of log diameter shows distinctive patterns by species, which indicate a necessity of differentiated diameter classes by species in an improved rules. Lengths of logs in productions do not corresponding to the demands and preferences in sawmills. Therefore it is highly recommended to include log length term in an improved log grading system. Based on these findings, 6 log grading systems for 3 species groups of softwood are newly proposed to improve current log grading rules. Limits of log diameter and log length are also proposed for each log grading system.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.544-558
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• 2017

The objective of this research is to investigate preservative efficacy for refractory species in field tests. The field tests were set up to evaluate the preservative performance of western hemlock and white spruce preservative-treated to the residential products group C and D of Canadian standard (CSA O80 Series-08) that have been developed for residential use in above-ground and ground-contact conditions, respectively. They were incised and pressure-treated with alkaline copper quaternary (ACQ) or copper azole (CA). Treated samples for the ground contact stake test and ground proximity test were installed in Jinju, Korea on November 2010 according to AWPA E7-09 and AWPA E18-06, respectively. Each sample has been annually assigned ratings for decay and termite attack, based on AWPA E7 grading system. After six years and five months of exposure, the untreated samples showed decay and particularly severe damage by termite attack but all the preservative-treated samples showed no decay. The results showed that the 5-mm penetration depths may be applicable for the treatment of refractory species. This paper discusses what to consider for the use of refractory species in Korean wood preservation industry from the penetration and retention points of view.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.746-756
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• 2015

The goal of this study was to review the wood shrinkage published in Journal of The Korean Wood Science and Technology from 1976 to 2015. Previous studies reported that shrinkage from Larix kaempferi in the tangential, radial, longitudinal directions ranged from 4.21%-9.79%, 2.09%-4.67%, 0.17%-0.33%, respectively. When different drying methods including closed cylinder drying, oven drying, and room temperature drying were used, volumetric shrinkage of Dipterocarpus grandiflorus was different, ranging from 31.6% to 21.0%. With an increment of the drying temperature of $115^{\circ}C$, $120^{\circ}C$, $125^{\circ}C$, the shrinkage of Larix kaempferi did not show a consistent trend. When sample size of Pinus densiflora was increased from $20{\times}20{\times}20mm$ to $100{\times}100{\times}100mm$, the tangential, radial and volumetric shrinkage decreased 2.61%, 1.32%, 0.80%, respectively. When a caliper having a sensitivity of 0.01 mm was used to measure $20mm^3$ specimen from Cryptomeria japonica, the measurement error occurred 1.97% in the radial direction and 35.7% in the longitudinal direction. From the previous studies, wood shrinkage could be influenced by sample size, drying method and measurement technique.

• Journal of the Korean Wood Science and Technology
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• v.41 no.6
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• pp.475-489
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• 2013

This work was conducted to investigate the effect of the addition of binders, such as rapeseed flour, coffee waste, bark, pine cone and lignin powder, on the fuel characteristics of the pellets fabricated with larch and tulip tree sawdust. Moisture content, bulk density and higher heating value of most pellets fabricated with the binders exceeded the 1st-grade pellet standard designated by Korea Forest Research Institute, but ash content of the pellets fabricated with rapeseed flour or bark of 10 wt% on the dry weight basis of sawdust was satisfied with just the 2nd- or 3rd-grade standard. The durability of tulip tree-pellets was positively influenced by the addition of rapeseed flour, coffee waste or lignin powder and increased with increasing the amount of the binders. For larch-pellets, the increase of binders did not greatly affect the durability, and even the durability reduced with the increase of bark or pine cone. From the microscopic observation, the obvious feature of pellet surfaces was not identified by the type of binder but by the addition amount of the binder. In summary, the addition of binders contributed to the fuel characteristics of wood pellets, and particularly the characteristics of wood pellets fabricated with coffee waste improved greatly. Therefore, if the binders are secured sufficiently with a reasonable cost, it might be possible to commercialize wood/binder pellets, which have better fuel characteristics than conventional wood pellets.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.757-767
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• 2015

This study was conducted to investigate the effects of moisture content and particle size of sawdust on the fuel characteristics of wood pellets produced with Mongolian oak (Quercus mongolica, QUM), red pine (Pinus densiflora, PID) and larch (Larix kaempferi, LAK) sawdust using a flat-die pelletizer. Prior to produce wood pellets, the sawdust was controlled to the moisture content of 8, 11, 12% and was screened to the particle size of 2 and 4 mesh. In the analysis of its chemical composition, QUM had a high ash content, and PID and LAK contained large amount of lignin. In case of the fuel characteristics, PID pellets had the lowest moisture content of pellets (P-MC), and LAR pellets was found to have the highest bilk density (BD) and durability (DU). With the increase of moisture content of sawdust (S-MC), P-MC and DU of QUM, PID and LAK pellets increased, but BD of QUM and LAK pellets decreased. When size of sawdust used for the production of wood pellets decreased, P-MC and BD of LAK pellets and BD of QUM pellets increased. Decrease of particle size contributed to the increase of DU of QUM, PID and LAK pellets. In addition, BD and DU of QUM pellets produced with 12% S-MC sawdust increased as its particle size reduced. For LAK pellets, DU was not influence by particle size in the S-MCs of 10% and 12%, but increased with the decrease of particle size in the S-MC of 8%. Based on the results and economical aspects, 10% MC and 2 mesh paricle size for QUM sawdust and 12% MC and 2 mesh particle size for PID sawdust might be optimal conditions for pellets production, and fuel characteristics of wood pellets produced by the conditions greatly exceeded the minimum requirements for the $1^{st}$-grade wood pellets of the standard designated by Korea Forest Research Institute.

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.373-380
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• 2022

In this study, Chung's equations 1, 2, and 3 were extended to standardize smoke safety rating evaluation in case of fire, and Chung's equations-V, smoke performance index-V, and smoke growth index-V were calculated. Five types of wood were selected and their smoke indices were measured using the cone calorimeter method according to ISO 5660-1. The smoke risk was graded by the smoke risk index-VI according to Chung's equation-VI. Smoke risk index-VI increased in the order of PMMA (1) ≈ maple (1.01) < ash (1.57) < needle fir (4.98) < paulownia (46.15) < western red cedar (106.26). It was predicted that maple and ash had the lowest smoke risk, and paulownia and western red cedar had the highest. The five samples' CO mean production rate (COP_mean) was 0.0009~0.0024 g/s, indicating that these woods were incompletely burned than the polymethyl methacrylate (PMMA) reference material. Regarding the smoke properties of the chosen woods, the smoke performance index-V (SPI-V) increased as the bulk density increased, and the smoke risk index-VI (SRI-VI) decreased.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.258-267
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• 2017

In this study, pitch pine (Pinus rigida, PIR) and Mongolian oak (Quercus mongolica, QUM) pellets were fabricated with bark or/and drying waste liquor (DWL) of larch (Larix kaempferi, LAK) as an additive. Based on the results of fuel characteristics of the pellets, optimal conditions for producing the high-quality pellets were provided. In the analysis of chemical composition, bark contained holocelluose and lignin of 90% and over. DWL had 0.1% solid assumed to sugars which are generated from the oven-drying of LAK logs. QUM showed high ash content (2.2%) by containing of bark in the sawdust. Bark and DWL of LAK had high ash content of 4% and over. Calorific values of all specimens and additives were higher than that of the $1^{st}$-grade standard of wood pellets designated by NIFOS (18.0 MJ/kg). PIR and QUM pellets were fabricated with additive of 2 wt% based on the solid weight of oven-dried sawdust using a piston-type flat-die pelletizer, and thus ash content and calorific value of the pellets did not affect by the use of additive. Durability of the pellets increased with the use of additive. Durabilties of pellets, which were fabricated with bark as an additive and DWL as a controller of moisture content for sawdust, did not differ from those of pellets without additives and were lower than those of pellets either with bark or DWL. However, use of both bark and DWL for the production of wood pellets might be favorable because it can make a profit from the collection process of DWL. Based on the results of fuel characteristics of the pellets, QUM and PIR pellets were produced by a flat-die pelletizer. Moisture content (MC), bulk density and durability of the pellets improved with the use of additive. Particularly, sawdust MC of 10% and the addition of bark or DWL for PIR as well as sawdust MC of 12% and the addition of bark for QUM might be optimal conditions for the production of high-quality pellets. Except for the ash content of QUM pellets, other properties of PIR and QUM pellets exceeded the $1^{st}$-grade wood pellets standards of NIFOS.