• Journal of Power Electronics
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• v.16 no.6
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• pp.2315-2326
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• 2016

This paper discusses the elimination of DC voltage deviation and the enhancement of load current sharing accuracy in multi-terminal high voltage direct current (MT-HVDC) systems. In order to minimize the power line losses in different parallel network topologies and to insure the stable operation of systems, a decentralized control method based on a modified droop control is presented in this paper. Averaging the DC output voltage and averaging the output current of two neighboring converters are employed to reduce the congestion of the communication network in a control system, and the decentralized control method is implemented. By minimizing the power loss of the cable, the optimal load current sharing proportion is derived in order to achieve rational current sharing among different converters. The validity of the proposed method using a low bandwidth communication (LBC) network for different topologies is verified. The influence of the parameters of the power cable on the control system stability is analyzed in detail. Finally, transient response simulations and experiments are performed to demonstrate the feasibility of the proposed control strategy for a MT-HVDC system.

• Smart Structures and Systems
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• v.30 no.5
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• pp.513-520
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• 2022

During the long-time service of a bolt, its preload may suffer slight perturbations or significant reductions. It is a dilemma to monitor preload changes at high resolution and full scale. Approaches for bolt preload monitoring with multi-resolution should be developed. In this paper, a simple and effective multi-resolution bolt preload monitoring approach using ultrasonic guided waves (UGW) is proposed. A linear relationship between the time-of-flight (TOF) variation of multi-reflected waves and preload is derived to theoretically reveal the multi-resolution properties of UGW. The variations of TOF before and after the slight preload perturbations are extracted by using a global evaluation method. Experimental results show that the signal-to-noise ratio (SNR) of the 1^st, 2^nd, and 3^rd-reflected UGWs is larger than 20 dB. The resolution of the 2^nd-reflected UGW is higher than that of the 1^st-reflected UGW and lower than that of the 3^rd-reflected UGW. The ultimate detectable resolutions of bolt preload (DRBP) of the 1^st and 3^th-reflected UGWs are 0.9% and 0.5%, respectively. By using the 1^st and 3^th-reflected guided waves, the bolt looseness with different degrees can be monitored simultaneously.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.1
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• pp.139-156
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• 2004

All Papers on Ecological Landscape Degign in KILA from 1973 to 2003 are listed herein for finding research issues and trends. The emerging field of Ecological studies of landscape design is based on Landscape Ecology and Watershed Ecology, the Principles of which can be applied to surveying and evaluation, Planning and design, construction and management focusing preservation of wildlife habitat and niche. This field can be classified into six categories: 1. Sustainable site planning and index, 2. Ecological planning process and regulation, 3. landscape ecology and biotope map, 4. Watershed and eco corridor project, 5. Urban forestry and environment, and 6. artificial ground and restoration ecology. The following is the summary of the findings from Paper review: 1. Sustainable index shall be studied about more specified sites. Water recycling facilities, and reservation wet land need to be studied. 2. Policy and legislation research on Ecological design shall be researched by expanding of the application field. Nature park planning and management fields shall be considered as the main theme of green networking Parts. 3. Landscape Ecological studies should be connected to practical surveying data, e.g. the eco-maps published by Environment Ministry. Traditional culture and science should be joined with the modem science. 4. Eco-corridor planning will go with the scenarios and theories of watershed ecology. 5. Urban forestry shall be studied with the wildlife's behavior and habitat. 6. Restoration engineering techniques should be reconsidered with the wildlife's existence and environmental affiliation.

• Journal of the Korean Society for Library and Information Science
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• v.54 no.4
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• pp.169-194
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• 2020

Recently, many academic fields are developing metadata to manage data produced in the field. Metadata to support a specific academic field beyond the general field is considered essential for searching, managing, sharing, and reusing research data in the field. Therefore, in this study, metadata items were derived to manage research data produced in forestry engineering. In order to derive metadata items, mapping work was performed on 7 metadata such as FGDC-CSDGM, ISO 19115, NEFIS, INSPIRE, ANZLIC, DataCite 4.3, and TTA.KO-10.0976. As a result of this study, 6 mandatory, 13 recommendations and 9 optional elements were derived. The derived metadata can be used as an item to systematically manage research data in the field of forestry engineering.

• Journal of the Korean Wood Science and Technology
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• v.44 no.6
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• pp.842-851
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• 2016

The objective of this study was to improve physical and mechanical properties of soft-inner part of oil palm trunk (S-OPT) after impregnation with phenol formaldehyde (PF) resin and densification by close system compression (CSC) method. Effect of different methods of PF resin impregnation (i.e., no vacuum-pressure, vacuum, and vacuum-pressure) was evaluated. The results showed that PF resin impregnation and CSC significantly improved the physical and mechanical properties of S-OPT up to: (1) 176% in density; (2) 309% in modulus of rupture (MOR); (3) 287% modulus of elasticity (MOE); and (4) 191% in the compressive strength. Physical and mechanical properties of S-OPT showed their best performances when PF resin impregnated with vacuum-pressure method as shown by higher weight gain, density, MOR, MOE, compressive strength, and lower recovery of set due to better penetration of PF resin into S-OPT. Combining PF resin impregnation and densification by CSC method could be a good method to improve physical and mechanical properties of S-OPT.

• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1388-1394
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• 2012

A xylanase-producing thermophilic strain, Geobacillus sp. TC-W7, was isolated from a hot spring in Yongtai (Fuzhou, China). Subsequently, the xylanase gene that encoded 407 amino acids was cloned and expressed. The recombinant xylanase was purified by GST affinity chromatography and exhibited maximum activity at $75^{\circ}C$ and a pH of 8.2. The enzyme was active up to $95^{\circ}C$ and showed activity over a wide pH range of 5.2 to 10.2. Additionally, the recombinant xylanase showed high thermostability and pH stability. More than 85% of the enzyme's activity was retained after incubation at $70^{\circ}C$ for 90 min at a pH of 8.2. The activity of the recombinant xylanase was enhanced by treatment with 10 mM enzyme inhibitors (DDT, Tween-20, 2-Me, or TritonX-100) and was inhibited by EDTA or PMSF. Its functionality was stable in the presence of $Li^+$, $Na^+$, and $K^+$, but inhibited by $Hg^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Pb^{2+}$, $Fe^{3+}$, and $Al^{3+}$. The functionality of the crude xylanase had similar properties to the recombinant xylanase except for when it was treated with $Al^{2+}$ or $Fe^{2+}$. The enzyme might be a promising candidate for various industrial applications such as the biofuel, food, and paper and pulp industries.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.112-122
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• 2009

Payment of Forest Landscape Service (PFLS) is based on the value of landscape conservation and is a positive forest policy inducing the owners of mountains to improve environmental service quality with economic incentives. The purpose of this study is to test the feasibility of PFLS and find out the elements related to PFLS such as associated statutes, target applications, eligible owner's requirements, and applicable environmental services. Research sites were selected in designated reserved forests by law and surveys were carried out with 28 professional forestry engineers and 10 owners of reserved forests located in Chungnam Province in November, 2008. As a result, the owners are willing to participate pilot-project of PFLS if they could have tax incentives. Preferred activities in their forestry are eco-tourism and carbon emission trading as PFLS business model. Although they expect low economic benefit from the PFLS, respondents answered introducing PFLS will give good opportunities for owners of a reserved forest to enhance willingness to manage their forestry properly for the landscape conservation. In this study, PFLS evaluation indicators and policy directions are established and recommends the strategies to cope with changing needs of forestry conservation by inducing the owners' active participation in the sustainable forest landscape management.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.145-162
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• 2019

This study aimed to increase the sugar and ethanol yield from the mengkuang plant biomass through biological and liquid hot water (LHW) pretreatment and their combination. The results showed that biological pretreatments with 5% inoculum of the fungus Trametes versicolor resulted in the highest alpha cellulose content incubated for 30 days, and 10% inoculum resulted in the lowest lignin content. LHW pretreatment decreased the hemicellulose content of pulps from 10.17% to 9.99%. T. versicolor altered the structure of the mengkuang pulp by degrading the lignin and lignocellulose matrix. The resulting delignification and cellulose degradation facilitate the hydrolysis of cellulose into sugars. The alpha cellulose content after biological-LHW pretreatment was higher (78.99%) compared to LHW-biological pretreatment (76.85%). Scanning electron microscopy analysis showed that biological-LHW combinated treatment degrades the cell wall structures. The ethanol yield for biological-LHW pretreated sample was observed 43.86% (13.11 g/L ethanol by weight of the substrate, which is much higher than that of LHW-biological pretreatment (34.02%; 9.097 g/L). The highest reducing sugar content about 45.10% was observed with a resulting ethanol content of 15.5 g/L at LHW pretreatment temperature of $180^{\circ}C$ for 30 min.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1613-1613
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• 2001

Fats and molasses are used, at the present time, in a considerable proportion as ingredients for the animal feed industry. They are mainly used as energy sources, but also they provide other characteristics of technological and nutritional interest (dust reduction, increase in palatability, etc). Both semi-liquid ingredients have numerous aspects in common from the point of view of their use in livestock feeds, as well as of their analytical control. Feed manufacturers use several criteria to evaluate the quality of fat and molasses. Furthermore, the traditional methods currently used, for their evaluation (eg. fatty acids, sugars, etc) are expensive and more sophisticated that the traditionally used for solid ingredients. The objective of the present work is to carry out a viability study to evaluate the ability of NIRS technology for the quality control of fat and molasses. Samples of liquid molasses (n = 42) and liquid fat ( n = 61), provided by a feed manufacturer, were scanned in a FOSS-NIR Systems 6500 monochromator equipped with a spinning module. The samples were analysed by folded transmission, using a sample cup of 0.1mm pathlength and gold surface reflector. For molasses, calibration equations were developed for the prediction of moisture (SECV=1.69%; $r^2$=0, 42), gross protein (SECV=0, 14%; $r^2$=0, 99), ashy (SECV=0, 60%; $r^2$=0, 84), NaCl (SECV=0, 05%; $r^2$=0, 99) and sugars (SECV=1, 04%; $r^2$=0, 86). For animal fats calibrations were obtained for the prediction of moisture (SECV=0, 14%, $r^2$=0, 88), acidity index (SECV=0, 83%, $r^2$=0, 82), MIU (SECV=0, 38%, $r^2$=0, 94) and unsaponifiables (SECV=0, 45%, $r^2$=0, 87). High accuracy calibration equations were also obtained for the prediction of the fatty acid profile. The equations have $r^2$values around 0.9 or highest. The results showed that NIRS technology could provide rapid and accurate results and reduce analytical costs associated to the quality control of two Important feed ingredients of a well known chemical variability.

• Journal of Climate Change Research
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• v.3 no.4
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• pp.281-291
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• 2012

Forests act as carbon sinks and also improve water resources and biodiversity to climate change. Secure funding, administrative support, and sustainable management systems are essential to conserve forests and to implement international forestry related projects to climate change. Public private partnership (PPP) could be an effective way for forestry sector in developing countries. Awareness analysis should be preceded in order to encourage participation of enterprises for the diversification of funding and the enhancing quality of projects. We conducted a survey targeting more than 129 private enterprises for awareness analysis. As a result, lack of information, complexity of processes and low profit resulted in low interest on forest projects from private enterprises. Improving awareness of recipient countries on forest resources, financial and institutional supports from the public sector, information sharing, performance management and equal partnership between sectors were suggested to encourage PPP in international forestry related projects to climate change.