• Title/Summary/Keyword: Forestry Engineering

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Current Status, Future Trend and General Policies of Forestry in China

  • Cheng, Ming;Ahmed, Sheikh Ali;Chun, Su-Kyoung;Kim, Jong-In
    • Journal of the Korea Furniture Society
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    • v.17 no.3
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    • pp.1-16
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    • 2006
  • Based on data collected by the State Forestry Administration (SFA) and other databases, this paper describes the current status, future trend and general policies in China's forestry. Forestry sector plays an important role in GDP growth of China. As a result forestry industry value output is increasing day by day. There is huge gap between demand and supply of timber projected in 2010. As a result it is necessary to develop fast growing, high yield forest following some specific policies. The ultimate goals of forestry are to construct or improve industry infrastructure, overall upgrade of forest industry structure, income improvement of forest employees and peasants, polices renewal and technology improvement, acceleration of forest processing with high-tech.

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Preparation and Characterization of Poly(lactic acid) Nanocomposites Reinforced with Lignin-containing Cellulose Nanofibrils (리그닌 함유 셀룰로오스 나노섬유로 강화된 폴리락틴산 나노복합재의 제조 및 분석)

  • Sun, Haibo;Wang, Xuan;Zhang, Liping
    • Polymer(Korea)
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    • v.38 no.4
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    • pp.464-470
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    • 2014
  • A chemo-mechanical method was used to prepare lignin-containing cellulose nanofibrils(L-CNF) from unbleached woodpulps dispersed uniformly in an organic solvent. L-CNF/PLA composites were obtained by solvent casting method. The effects of L-CNF concentration on the composite performances were characterized by tensile test machine, contact angle machine, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The tensile test results indicated that the tensile strength and elongation-at-break increased by 50.6% and 31.8% compared with pure PLA. The contact angle of PLA composites decreased from $79.3^{\circ}$ to $68.9^{\circ}$. The FTIR analysis successfully showed that L-CNF had formed intermolecular hydrogen bonding with PLA matrix.

Synergistic Effect of 3A Zeolite on The Flame Retardant Properties of Poplar Plywood Treated with APP

  • Wang, Mingzhi;Ji, Haiping;Li, Li
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.2
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    • pp.258-264
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    • 2015
  • To evaluate the influence of 3A zeolite on the flame retardant properties of poplar plywood. Ammonium polyphosphate (APP) and 3A zeolite were used as flame retardants to prepare plywood samples. The combustion properties, such as heat release rate (HRR), total heat release (THR), mean CO and $CO_2$ yield, smoke production rate (SPR), and total smoke production (TSP), were characterized by a cone calorimeter. A synergistic effect was observed between 3A zeolite and APP on reducing the HRR and mean CO yield. The probable flame retardation mechanism was proposed.

Characterization of Glycerol Dehydrogenase from Thermoanaerobacterium thermosaccharolyticum DSM 571 and GGG Motif Identification

  • Wang, Liangliang;Wang, Jiajun;Shi, Hao;Gu, Huaxiang;Zhang, Yu;Li, Xun;Wang, Fei
    • Journal of Microbiology and Biotechnology
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    • v.26 no.6
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    • pp.1077-1086
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    • 2016
  • Glycerol dehydrogenases (GlyDHs) are essential for glycerol metabolism in vivo, catalyzing its reversible reduction to 1,3-dihydroxypropranone (DHA). The gldA gene encoding a putative GlyDH was cloned from Thermoanaerobacterium thermosaccharolyticum DSM 571 (TtGlyDH) and expressed in Escherichia coli. The presence of Mn2+ enhanced its enzymatic activity by 79.5%. Three highly conserved residues (Asp171, His254, and His271) in TtGlyDH were associated with metal ion binding. Based on an investigation of glycerol oxidation and DHA reduction, TtGlyDH showed maximum activity towards glycerol at 60℃ and pH 8.0 and towards DHA at 60℃ and pH 6.0. DHA reduction was the dominant reaction, with a lower Km(DHA) of 1.08 ± 0.13 mM and Vmax of 0.0053 ± 0.0001 mM/s, compared with glycerol oxidation, with a Km(glycerol) of 30.29 ± 3.42 mM and Vmax of 0.042 ± 0.002 mM/s. TtGlyDH had an apparent activation energy of 312.94 kJ/mol. The recombinant TtGlyDH was thermostable, maintaining 65% of its activity after a 2-h incubation at 60℃. Molecular modeling and site-directed mutagenesis analyses demonstrated that TtGlyDH had an atypical dinucleotide binding motif (GGG motif) and a basic residue Arg43, both related to dinucleotide binding.

Current Status, Future Trend and General Policies of Forestry in China

  • Cheng, Ming;Chun, Su-Kyoung
    • Proceedings of the KSFDT Conference
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    • 2006.04a
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    • pp.99-113
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    • 2006
  • With the economy reform carried on deeply step by step, forestry industry is playing a more and more important role in the country's economy. How to use the limited resources to make the largest economical benefit is a key point for the industry development, however it is exciting that our forest resources is on sustainable development gradually and forestry output value is also increasing every year, input and export volume is enlarged fast, add to reasonable strategy, no doubt that China's forestry can achieve a prosperous future.

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Key technologies research on the response of a double-story isolated structure subjected to long-period earthquake motion

  • Liang Gao;Dewen Liu;Yuan Zhang;Yanping Zheng;Jingran Xu;Zhiang Li;Min Lei
    • Earthquakes and Structures
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    • v.26 no.1
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    • pp.17-30
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    • 2024
  • Earthquakes can lead to substantial damage to buildings, with long-period ground motion being particularly destructive. The design of high-performance building structures has become a prominent focus of research. The double-story isolated structure is a novel type of isolated structure developed from base isolated structure. To delve deeper into the building performance of double-story isolated structures, the double-story isolated structure was constructed with the upper isolated layer located in different layers, alongside a base isolated structure for comparative analysis. Nonlinear elastoplastic analyses were conducted on these structures using different ground motion inputs, including ordinary ground motion, near-field impulsive ground motion, and far-field harmonic ground motion. The results demonstrate that the double-story isolated structure can extend the structural period further than the base isolated structure under three types of ground motions. The double-story isolated structure exhibits lower base shear, inter-story displacement, base isolated layer displacement, story shear, and maximum acceleration of the top layer, compared to the base isolated structure. In addition, the double-story isolated structure generates fewer plastic hinges in the frame, causes less damage to the core tube, and experiences smaller overturning moments, demonstrating excellent resistance to overturning and a shock-absorbing effect. As the upper isolated layer is positioned higher, the compressive stress on the isolated bearings of the upper isolated layer in the double-story isolated structure gradually decreases. Moreover, the compressive stress on the isolated bearings of the base isolated layer is lower compared to that of the base isolated structure. However, the shock-absorbing capacity of the double-story isolated structure is significantly increased when the upper isolated layer is located in the middle and lower section. Notably, in regions exposed to long-period ground motion, a double-story isolated structure can experience greater seismic response and reduced shock-absorbing capacity, which may be detrimental to the structure.

Comparison of Two Laccases from Trametes versicolor for Application in the Decolorization of Dyes

  • Li, Qi;Ge, Lin;Cai, Junli;Pei, Jianjun;Xie, Jingcong;Zhao, Linguo
    • Journal of Microbiology and Biotechnology
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    • v.24 no.4
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    • pp.545-555
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    • 2014
  • It has been previously demonstrated that laccases exhibit great potential for use in several industrial and environmental applications. In this paper, two laccase isoenzyme genes, lccB and lccC, were cloned and expressed in Pichia pastoris GS115. The sequence analysis indicated that the lccB and lccC genes consisted of 1,563 and 1,584 bp, and their open reading frames encoded 520 and 527 amino acids, respectively. They had 72.7% degree of identity in nucleotides and 86.7% in amino acids. The expression levels of LccB and LccC were up to 32,479 and 34,231 U/l, respectively. The recombinant laccases were purified by ultrafiltration and $(NH_4)_2SO_4$ precipitation, showing a single band on SDS-PAGE, which had a molecular mass of 58 kDa. The optimal pH and temperature for LccB were 2.0 and $55^{\circ}C$ with 2,2'-azinobis-[ 3-ethylbenzthiazolinesulfonic acid (ABTS) as a substrate, whereas LccC exhibited optimal pH and temperature at 3.0 and $60^{\circ}C$. The apparent kinetic parameters of LccB were 0.43 mM for ABTS with a $V_{max}$ value of 51.28 U/mg, and the Km and $V_{max}$ values for LccC were 0.29 mM and 62.89 U/mg. The recombinant laccases were able to decolorize five types of dyes. Acid Violet 43 (100 g/ml) was completely decolorized by LccB or LccC (2 U/ml), and the decolorization of Reactive Blue KN-R (100 g/ml) was 91.6% by LccC (2 U/ml). Thus, the study characterizes useful laccase isoenzymes from T. versicolor that have the capability of being incorporated into the treatment of similar azo and anthraquinone dyes from dyeing industries.

Effects of vortex generators on the wind load of a flat roof: A computational study

  • Zhao, Yagebai;Deng, Xiaolong;Zhang, Hongfu;Xin, Dabo;Liu, Zhiwen
    • Wind and Structures
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    • v.32 no.1
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    • pp.1-9
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    • 2021
  • Vortex generators are commonly used in mechanical engineering and the aerospace industry to suppress flow separation owing to their advantages of simple structure, economic viability, and high level of efficiency. Owing to the flow separation of the incoming wind on the leading edge, a suction area is formed on the roof surface, which results in a lifting effect on the roof. In this research, vortex generators were installed on the windward surface of a flat roof and used to disturb to roof flow field and reduced suction based on flow control theory. Computational fluid dynamics (CFD) simulations were performed in this study to investigate the effects of vortex generators on reduce suction. It was determined that when the vortex generator was installed on the top of the roof on the windward surface, it had a significant control effect on reduce suction on the roof leading edge. In addition, the influence of parameters such as size, placement interval, and placement position of the vortex generator on the control effect of the roof's suction is also discussed.

Analyzing the correlation between urban forestry and surface temperature using Landsat TM data

  • Jo, Myung-Hee;Kim, Sung-Jae;Lee, Kwang-Jae
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.905-907
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    • 2003
  • In this study, the correlation between the heat island effect and the vegetation in Deagu Korea was performed through using Landsat TM data. the island effect, presents high temperature on air like island, is connected with correlation between the surface temperature and the temperature on the air. In this study, surface temperature was analyzed by detecting the change of urban forestry with remote sensing using the vegetation vitality statistics reference (ratio change of the Park greens in Daegu) the heat island effect not only brings the environment pollution but also brings serious problem such as the destruction of ecosystem to city as a whole. Jeff Luvall has studied to restrain the heat island effect by making urban forestry. Even though Daegu had been the serious high temperature urban area the current temperature of Daegu has been dropped. The correlation between the heat island effect and the vegetation index was analyzed by using satellite images.

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