• Journal of the Korean Wood Science and Technology
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• 제30권3호
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• pp.42-47
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• 2002

This study was carried out to investigate the constituents of Sophora japonica(Leguminosae) bark. To isolate compounds, bark was extracted with ethanol and then partitioned with hexane, dichloromethane, ethylacetate and butanol successively. After partitioned, DCM fraction was subjected to column chromatography with various solvent system in silica gel and/or Sephadex LH-20. Structures were elucidated by spectroscopic methods including MS, ¹H, ¹³C and 2D-NMR experiments. Four compounds were isolated from the bark and identified as 3',7-dihydroxy-4'-methoxyisoflavone (cyclosin), puerol A, maackiain-3-O-𝛽-D-glucopyranoside (trifolirhizin), and 4', 5, 7-trihydroxyisoflavone (genistein). Among these compounds, cyclosin and trifolirhzin were first isolated from S. japonica.

• Journal of the Korean Wood Science and Technology
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• 제51권1호
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• pp.14-22
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• 2023

Economical use of larix (larch) boards (grade 3) in industries is lower than that of imported hardwood; thus, studies have been conducted toward performance improvement of larix boards. Herein, flexural modulus of larix board samples laminated with wood adhesives polyurethane resins, poly (vinyl acetate) resins, phenol-resorcinol-formaldehyde resins, melamine-formaldehyde resins, and urea-formaldehyde resins was compared with that of the samples bonded with adhesives reinforced with mesh-type basalt fibers. Moreover, the flexural moduli of the laminated samples bonded by mesh-type basalt fibers were compared with those of reinforced samples. The results showed that boards laminated with polyurethane and urea-formaldehyde resin adhesives had higher flexural modulus than those without the lamination. In particular, the increase in the flexural modulus was relatively significant for the 2- and 3-ply board structures laminated with polyurethane adhesives compared to those with reinforcement. The 3-ply board structure without reinforcement had the highest flexural modulus when the urea-formaldehyde resin adhesive was used.

• Journal of the Korean Wood Science and Technology
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• 제44권5호
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• pp.736-742
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• 2016

나무못은 다양한 구조물의 목재부재들을 연결하는데 일반적으로 사용된다. 하지만 국산재의 나무못 유지력에 대한 자료는 매우 부족하다. 본 연구는 나무못의 직경과 천공여척이 유지력 특성에 미치는 영향에 대해 알아보기 위해 실시했다. 실험 블록은 두께 15 mm인 소나무와 잣나무 목재로 제작했다. 6, 8 및 10 mm 직경인 나무못은 밤나무, 잣나무 및 백합나무 목재로 각각 제작했다. 연구결과 나무못 직경이 증가하면 유지력은 선형으로 증가했지만 유지력 강도는 감소했다. 본 연구는 또한 천공여척이 작아질수록 유지력과 유지력 강도도 선형으로 증가하는 것을 보였다.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.605-614
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• 2014

This study investigated microstructural changes of cured urea-formaldehyde (UF) resins mixed with aqueous rubber latex emulsion after intentional acid etching. Transmission electron microscopy (TEM) was used in order to better understand a hydrolytic degradation process of cured UF resins responsible for the formaldehyde emission from wood-based composite panels. A liquid UF resin with a formaldehyde to urea (F/U) molar ratio 1.0 was mixed with a rubber latex emulsion at three different mixing mass ratios (UF resin to latex = 30:70, 50:50, and 70:30). The rate of curing of the liquid modified UF resins decreased with an increase of the rubber latex proportion as determined by differential scanning calorimetry (DSC) measurement. Ultrathin sections of modified and cured UF resin films were exposed to hydrochloric acid etching in order to mimic a certain hydrolytic degradation. TEM observation showed spherical particles and various cavities in the cured UF resins after the acid etching, indicating that the acid etching had hydrolytically degraded some part of the cured UF resin by acid hydrolysis, also showing spherical particles of cured UF resin dispersed in the latex matrix. These results suggested that spherical structures of cured UF resin might play an important role in hindering the hydrolysis degradation of cured UF resin.

• Journal of the Korean Wood Science and Technology
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• 제24권2호
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• pp.55-60
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• 1996

Tripitaka Koreana were made during Coryo Dynasty from 1236 to 1251 A.D. Buddhist scriptures were engraved on 81.340 wooden plates. Some plates were varnished with Rhus lacquer, but most of them were uncoated. Macroscopically, most of the plates appeared intact due to the storage in a well-ventilated wooden house. Because, they were irregularly used for printings with ink, it can be assumed that they were repeatedly exposed to ink-water and drying processes. The present were made to examine the changes of wood cell structures occurred during long-term aging deterioration processes in these dry archaeological wooden plates. Light, scanning and transmission electron microscopes were employed for this study. Wedge-shaped cracks and delamilations were found from the lumen side toward the compound middle lamellae and they progressed toward primary or secondary walls. A large amount of hypae in vessels and the degradation of vessel-ray pit walls by the fungal hyphae were observed. When compared to the recent wood, the birefringence of wood fibers was considerably lower or completly disappeared, suggesting the degradation of crystalline cellulose in these wood samples. The degradation of the cell wall could be also revealed the calculation of crystallinity with X-ray diffraction and the size of crystalline region was estimated.

• Journal of the Korean Wood Science and Technology
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• 제44권3호
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• pp.440-448
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• 2016

본 연구는 WUFI Pro 5.3을 이용하여 한국농어촌공사에서 제시하고 있는 농어촌 표준 목조주택 설계를 기준으로 목조 벽체의 hygrothermal 거동에 대한 평가를 실시하였다. 그 결과, 2010년도에 제시된 벽체보다 2014년도에 개선된 벽체의 Total Water Contents (TWC)가 더 낮게 나타난 것을 확인하였고, 3년간의 평가에서 TWC가 일정하게 유지되는 동적 안정 상태에 도달하였음을 보아 hygrothermal 환경을 적절히 고려하는 개선임을 확인하였다. 또한 농촌지역과 어촌지역을 구분지어 hygrothermal 거동을 평가한 결과, 벽체가 해당지역의 온도보다 상대습도에 큰 영향을 미치는 것을 확인하였다. 또한, 목재 기반 재료의 과도한 수분 함량 문제는 실외마감의 재료를 바꾸는 것으로 어촌지역에도 적용이 가능한 벽체로 개선할 수 있었다. 곰팡이 성장 위험의 경우, 초기 실내 설정온도에서 여름철에 곰팡이가 성장할 가능성이 높은 것으로 나타났으며, 이를 고려하여 여름철 실내 설정온도를 변화시키는 것으로 개선되었다. 이러한 결과를 통해, 건축설계 단계에서 WUFI 프로그램과 같은 hygrothermal 거동 분석 프로그램을 이용하여 건축물의 수분에 대한 문제를 미리 분석하고 이에 맞는 벽체의 개선이 필요하다고 판단된다.

• Journal of the Korean Wood Science and Technology
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• 제31권1호
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• pp.1-9
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• 2003

항균활성이 우수한 헛개나무 목부 에탄올 조추출물로부터 7종의 화합물을 단리하였으며, 기기분석 결과 flavonoid인 5-hydroxy-7-methoxyflavone를 비롯하여 5,7-dihydroxyflavone (chrysin), 5,7-dihydroxyflavanone (pinocembrin), 3,5,7-trihydroxyflavanone (pinobanksin), 3,4',5,7-tetrahydroxyflavanone (aromadendrin)과 stilbenoid인 3-hydroxy-5-methoxystilbene과 3,5-dihydroxystilbene (pinosylvin)으로 각각 동정되었다. 이들 단리물질에 대한 항균활성을 조사한 결과 stilbenoid인 3-hydroxy-5-methoxystilbene이 공시균주의 생장을 완전히 저해하여 단리물질 중 활성이 가장 높은 것으로 나타났다. 그 다음이 pinocembrin과 pinosylvin으로 Cryphonectria parasitica, Trametes versicolor, Tyromyces palustris 그리고 Trichoderma viride에 대해 높은 균사생장억제율을 나타내어 활성이 우수한 것으로 나타났다. 그러나, flavonoid인 pinobanksin, 5- hydroxy-7-methoxyflavone, chrysin, 그리고 aromadendrin은 항균활성이 낮은 것으로 나타났다. 이상의 결과, 헛개나무 목부 에탄올 조추출물의 높은 항균활성은 3-hydroxy-5-methoxystilbene과 pinocembrin, 그리고 pinosylvin에서 유래된 것으로 사료되었다.

• 임산에너지
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• 제18권2호
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• pp.62-69
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• 1999

목재 세포벽중의 셀룰로오스의 알칼리 팽윤구조는 리그닌에 의해 크게 영향을 받는다. 본 연구에서는 알칼리 팽윤특성에 관한 리그닌의 영향을 명확히 하기 위하여 신갈나무의 정상재 및 부후재를 이용하여 X선 회절법과 자외선 현미경법에 의해 검토하였다. 그 결과, 목재 셀룰로오스는 고농도의 알칼리 수용액 중에서 머서화 처리를 하여도 결정변태가 일어나지 않으며 탈리그닌 후에도 결정의 변화는 없었다. 즉, 목재세포벽중의 셀롤로오스 결정은 리그닌의 존재에 의해 알칼리 팽윤이 억제되어 결정의 변태는 발생하지 않으며 탈리그닌 후에도 결정의 구조는 변화되지 않는 것으로 생각되었다.

• Journal of the Korean Wood Science and Technology
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• 제48권6호
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• pp.769-779
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• 2020

This study investigates the selective fractionation of lignin with uniform structures and lower molecular weight. Lignin solubilization was first performed using a solution of acetic acid (AA) and hydrogen peroxide (HP) (4:1, (v/v)) to form peracetic acid (PAA), which is a strong oxidant. After the PAA-induced solubilization that occurred at 80℃, totally soluble lignin was extracted by ethyl acetate (EA) and divided into organic- and water-soluble fractions. The EA fraction was then fractionated by open-column using three solutions (chloroform-ethyl acetate, methanol, and water) sequentially. With an increase in the solvent polarity during the fractionation step, the molecular weight of the lignin-derived compounds in the fraction increased. Remarkably, some lignin fractions did not have aromatic structures. These fractions were identified as carboxylic acid-containing polymers like poly-carboxylates. These results conclude that the selective production of lignin-derived polymers with specific molecular weight and structural characteristics could be possible through open-column fractionation.

• Earthquakes and Structures
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• 제13권3호
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• pp.289-297
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• 2017

This paper presents seismic performance and reliability evaluation on steel-timber hybrid shear wall systems composed of steel moment resisting frames and infill light frame wood shear walls. Based on experimental observations, damage assessment was conducted to determine the appropriate damage-related performance objectives for the hybrid shear wall systems. Incremental time-history dynamic analyses were conducted to establish a database of seismic responses for the hybrid systems with various structural configurations. The associated reliability indices and failure probabilities were calculated by two reliability methods (i.e., fragility analysis and response surface method). Both methods yielded similar estimations of failure probabilities. This study indicated the greatly improved seismic performance of the steel-timber hybrid shear wall systems with stronger infill wood shear walls. From a probabilistic perspective, the presented results give some insights on quantifying the seismic performance of the hybrid system under different seismic hazard levels. The reliability-based approaches also serve as efficient tools to assess the performance-based seismic design methodology and calibration of relative code provisions for the proposed steel-timber hybrid shear wall systems.