• 한국산업보건학회지
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• 제9권2호
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• pp.145-157
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• 1999

Wood dust is created when machines are used to cut or shape wood materials. Industries of high risk of wood dust exposure are sawmills, dimension mills, furniture industries, and carpenters, etc. Health effects associated with wood dust exposure includes dermatitis, allergic respiratory effects and cancer. Health effects of wood dus t are mainly depend on the concentration, dust size and exposure time. This study were carried out to evaluate the concentration and particle size distribution of wood dust during working processes. The subjects of this study were 53 workers exposed to wood dust in 7 furniture factories and 5 musical instruments, and 5 sawmill factories. The average total wood dust concentrations measured by personal cascade impactor were $1.82{\pm}2.31mg/m^3$ in primary manufacture, $3.59{\pm}1.72mg/m^3$ in s econdary manufacture, $5.09{\pm}1.46mg/m^3$ in sanding operation. Mass median diameters of hardwoods dust were $3.36{\mu}m$ in primary manufacture, $4.25{\mu}m$ in secondary manufacture, $4.21{\mu}m$ in sanding operation. softwoods dust were $3.39{\mu}m$ in primary manufacture, $4.34{\mu}m$ in secondary manufacture. Particle size distributions showed a nearly the same pattern in each working processes. The sample concentration of all hardwood dust exceeded the Threshold Limit Value(TLV) and 20.8% of the softwood dust exceeded the Threshold Limit Value. The range of size distribution were $0.5-10{\mu}m$ in the soft and hardwood dust. The respirable dust of soft and hardwood took up 59% and above. Therefore new threshold limit value for wood dust should be needed in Korea. Also, it should be done for various studies on health effects related to occupational exposure of wood dust.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.373-379
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• 2006

Fiber characteristics and fiber distribution of thermomechanical pulp(TMP), bisulfite chemithermomechanical pulp(bisulfite CTMP), neutral sulfite chemithermomechanical pulp(neutral sulfite CTMP) from kenaf(Hibiscus cannabinus L., Malvaceae) cultivar Tainug-2 cultivated in the reclaimed land of Korea were examined to use effectively nonwood fibers as an alternative raw material sources for papermaking. Yields of TMP and CTMP from kenaf were lower than those of TMP from hardwoods and CTMP from softwoods and hardwoods. Bark fibers of kenaf cultivar Tainung-2 ranged 2.04 to 2.30 mm long and $18.7{\sim}19.7{\mu}m$ width. Core fibers averaged 0.63 to 0.80 mm long and $29.5{\sim}31.4{\mu}m$ wide. Coarseness of bark fiber was higher than that of core fiber, and fiber from TMP were higher than those from both bisulfite CTMP and neutral sulfite CTMP. Curl indexes of bark fibers were higher than those of core fibers. However curl indexes were not significantly affected by the pulping conditions. Short fiber distributions were higher in core fibers from TMP and CTMP and long fiber distributions were higher in bark fibers. There was no significant difference in fiber distribution of whole and core fibers obtained from TMP and CTMP, Fibers from neutral sulfite CTMP, however, exhibited a little higher long fiber distribution. Distinct difference in anatomical characteristics was found between core and bast fibers of kenaf plant. Parenchyma cell, pith parenchyma cell and vessel were observed in core fibers and bast fiber in bast sections.

• Journal of the Korean Wood Science and Technology
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• 제43권4호
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• pp.429-437
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• 2015

아세틸화처리는 목재의 치수안정성을 높이는 방법으로 알려졌다. 기상처리보다는 액상처리가 중량증가율이 높기 때문에 더 많이 사용된다. 국내산 소나무재와 잣나무재를 액상 아세틸화처리하여 밀도, 휨강도, 치수안정성 등 물리적 성질에 미치는 효과를 조사하였다. 아세틸화처리에 의한 소나무와 잣나무 시편의 중량은 각각 평균 10.4%와 9.2% 증가하였으며, 전건밀도는 각각 평균 6.9%와 4.6% 증가하였다. 소나무와 잣나무 모두 휨파괴계수(MOR)와 휨탄성계수(MOE), 동탄성계수(DMOE)의 변화는 없었다. 아세틸화처리 후 목재시료의 평균 항흡습률(PRH)은 소나무와 잣나무가 각각 20.6%와 13.8% 이었다. 평균 항흡수율(PRA)은 소나무와 잣나무가 각각 20.0%와 8.5%였다. 따라서 아세틸화처리에 의해 소나무의 치수안정성이 향상된 결과를 얻었다.

• Journal of the Korean Wood Science and Technology
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• 제35권6호
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• pp.152-158
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• 2007

갈생부후균의 침해를 받은 생입목(生立木) 상태의 밤나무 및 사시나무속 갈색부후재의 미시형태 및 화학적 특징을 분석하였다. 활엽수 갈색부후재는 침엽수 갈색부후재에서 나타나는 전형적인 특징 즉 복굴절의 감소, 2차벽 중증($S_2$)의 선택적 분해 및 세포벽의 갈라짐 현상을 보여주었다. 부분적으로 목섬유의 박벽화 현상도 관찰되었으나 주 분해형태는 아니었다. FT-IR 분석결과 셀룰로오스의 헤미셀룰로오스를 나타내는 band가 현저히 감소한 반면 리그닌을 가리키는 band는 증가되어 나타났다. X선 회절분석 결과 공시된 활엽수재의 상대 결정화도는 건전재에 비해 감소되어 나타난 것으로 보아, 갈색부후가 상당히 진전되었음을 보여주었다.

• 한국가구학회지
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• 제12권1호
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• pp.11-20
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• 2001

To investigate weathering and surface characteristics of coating film on lumbers coated with Hwangchil(varnish of Dendropanax morbifera), we carried out to investigate the resistance against discoloration, value of crack and surface characteristics of coating films on seven domestic lumbers and those of four introduced tropical lumbers. There was investigated to evaluate the properties of coating films by the varnish of Dendropanax morbifera. There was insignificant correlations between the hardness and moisture contents of each lumber treated by the varnish. There was no significant correlations between the thickness of coating film and the hardness, either. Although we investigated 11 wood species, we found only three species as resistance wood species against discoloration; Diospysos spp., Abies holophylla and Ulmus davidiana. The crack of coaing films was the largest on Zelkova serrata followed by Juglans sinensis, Cercidiphum japonicum, Tectona grands, Ulmus davidiana, Guibourtia tessmannii, Diospysos spp. and Dalbergia latifolia. However, there was no crack of coating films on the lumbers of Juniperus rigida, Prunus serrulata var. spontanea and Abies holophylla. The crack of coating film showed positive correlations with the thickness of coating film and hardness. The surface characteristics of the coating films evaluated on the basis of $R_{a}$ values indicated the lumbers of Ulmus davidiana($0.14{\;}{\mu}m$), Juniperus rigida($0.1 5{\;}{\mu}m$), Guibourtia tessmannii($0.19{\;}{\mu}m$), Dalvergia latifolia($0.20{\;}{\mu}m$) and Diospysos spp.($0.20{\;}{\mu}m$), Cercidiphum japonicum($0.24{\;}{\mu}m$) as good species while there was insignificant differences between softwoods and hardwoods. Tectona grands, Prunus serrulata var. spontanea and Abies holophylla showed rough surface with $1.53~2.63{\;}{\mu}m$ of $R_a$ values. The four kinds of rough indices($R_a,{\;}R_z,{\;}R_{max}{\;}and{\;}R_q$) showed very low correlations with moisture contents with the correlation coefficients. The $R_a{\;}and{\;}R_{max}$ also showed slight relationship with hardness.

• Journal of the Korean Wood Science and Technology
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• 제14권1호
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• pp.55-60
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• 1986

Discoloration sensitivities of woods grown in this country haven't reported yet. Therefore we examined discoloration sensitivities of domestic wood specimens to iron (0.1 %, $FeCl_3.6H_2O$), alkali (pH 12.0, NaOH). acid (pH 1.0, $C_2H_2O_4$) and exposing to sunlight (40 hrs), Thirty-six hardwood species were collected and examined. All specimens were prepared from heartwoods of the collected species. But the specimens of 4 Betula species were divided into sapwoods and heartwoods. By iron stain, the color differences (${\Delta}E$) of 21 wood specimens including one Betula sapwood showed above 12.0, which means strong discoloration sensitivities, and of 3 specimens including one Betula sapwood showed below 2.5, which means weak discolorations. The most strong iron discoloration species was Jungkukgulpi-namu (Pterocarya stenoptera). By alkali stain, the color differences (${\Delta}E$) of 3 wood specimens showed above 9.0, which means strong discoloration sensitivities, and of 18 wood specimens including 4 Berula sapwoods showed below 2.5, which means weak discolorations. By acid stain, the color differences (${\Delta}E$) of 6 wood specimens showed above 10.0 which means strong discoloration sensitivities, and of 12 wood specimens including one Betula sapwoods showed below 2.5, which means weak discolorations. By exposing to sunlight, the color differences (${\Delta}E$) of 31 wood specimens including one Betula sapwoods showed below 6.5, which means, strong discoloration sensitivities, and of only one specimens showed below 2.5, which means weak discoloration. The most strong discoloration species by exposing to sunlight was Guirung-namu (Prunus padus). In general, it was shown that hardwoods grown in Korea were most subject to change of color by exposing to sunlight and next were by iron stain. Domestic hardwoods showed some differences in discoloration sensitivities from domestic softwoods previously reported.

• 농업과학연구
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• 제28권2호
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• pp.125-131
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• 2001

백색부후균 Trametes versicolor(CV5) 균주에 의한 wood lignin의 분해능을 조사하였다. CV5는 활엽수와 침엽수에 속하는 여러 수종의 프로토 리그닌 분해 시 활엽수에 한해서 분해되는 특성을 보였으며, 특히 상수리나무에서 33.5%의 가장 높은 리그닌이 분해되었다. 리그닌 분해에 관련된 phenoloxidase 분비능을 Bavendamm 시험을 통해 검토한 결과 CV5는 지금까지 연구된 우수 백색 부후균과 같은 유사 반응 형태를 나타내고 있음을 확인하였다. 또한 상수리 목재 chip표면에 CV5의 균사가 생육하면서 목재조직이 부후된 상태를 주사전자 현미경으로 관찰한 결과 목섬유 및 도관에서 균사의 침투와 목재조직의 분해를 확인하고 리그닌에 대한 높은 선택적 분해력을 갖고 있음을 구명하였다.

• 건축역사연구
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• 제16권1호
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• pp.9-28
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• 2007

We investigated the changes in the species of the woods used for Korean ancient and historic architectures, which include prehistoric excavated relics and existing wooden buildings in South Korea. The species data were collected from various sources such as excavation and repair reports, journal papers, and a few unpublished documents. We divided the building Periods as Paleolithic, Neolitic, Bronze Ages, Iron Age/Three Kingdoms, Koryo, Joseon (early, middle, late) and modem periods. In prehistoric periods, hardwoods were major species. Oak (Quercus spp.) woods dominated (94 percent in average); the others (5%) were Juglans mandshurica, Platycarya strobilacea, Castanea crenata, and few softwoods(1%). During Iron Age and Three Kingdom periods, oaks remained as a major species (57%) and others Platycarya strobilacea(21%), Castanea crenata(13%), and Pinus spp. (6%). The oak woods decreased in Koryo period and they occupied only 1.1%. Instead of oaks, pine (Pinus spp., 71%) and Zelkova serrata (22%) dominated in Koryo. In early and middle Joseon periods, pine woods (73%) remain as a major species and the others were oaks (14%) and Zelkova serrata (9%). As late Joseon came, the pine woods occupied more than 88%. In the late 19th and early 20th centuries, a few boreal species such as larch (Larix spp.) and spruce (Picea spp.), which grow in cold area, were found. We believe they were transported from northern Korea. The existing buildings in Korea are mainly from Joseon period and a few from late Koryo periods. During these periods, pine woods were used for most buildings. For such reason, pine woods were known as 'representative materials for historic buildings'. but earlier times, broad-leaved trees, i.e., oak and Zelkova woods were major materials. The changes in building materials resulted from both climate and human impacts. The dry climate and disturbed forests induce more pines in the mountains. We also compared the wood qualities of the species and found that Zelkova woods were superior ones and deserved more planting for future demands in the repair for historic buildings.

• Journal of the Korean Wood Science and Technology
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• 제49권5호
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• pp.504-513
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• 2021

In this study, cross-laminated wood panels were manufactured with four softwoods and three hardwoods with the goal of efficiently predicting the static strength performance using dynamic modulus of elasticity (MOE) and simultaneously revealing the dynamic performance of cross-laminated wood panels. The effect of the density of the species on the dynamic MOE of the laminated wood panels was investigated. Moreover, the static bending strength performance was predicted nondestructively through the correlation regression between the dynamic MOE and static bending strength performance. For the dynamic MOE, the parallel- and cross-laminated wood panels composed of oriental oak showed the highest value, whereas the laminated wood panels composed of Japanese cedar showed the lowest value. In all types of parallel- and cross-laminated wood panels, the density dependence was confirmed, and the extent of the density dependence was found to be greater in the P_⊥ and C_⊥ types with perpendicular-direction laminae in the faces than in the P_∥ and C_∥ types with longitudinal-direction laminae in the faces. Our findings confirmed that a high correlation exists at a significance level of 1% between the dynamic modulus and static bending modulus or bending strength in all types of laminated wood panels, and that the static bending strength performance can be predicted through the dynamic MOE.

• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.509-518
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• 2019

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.