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CES/IEEE 5th International Power Electronics and Motion Control Conference

作者： Ahmed G.Abo-Khalil Dong-Choon Lee Se-Hyun Lee dept.of electrical.eng.yeungnam univ. 214-1DaedongGyeongsanGyeongbukKorea dept.of electrical.eng.yeungnam univ. 214-1DaedongGyeongsanGyeongbukKorea Electro-Mechanical Research Institute Hyundai Heavy Industry Co.LtdGyeongkiKorea

＜正＞This paper presents a new synchronization algorithm for grid connection of a doubly fed induction generator （DFIG） in wind generation system. A stator flux-oriented vector control is used for the variable speed DFIG operation. By controlling the generator excitation current the amplitude of the stator EMF is adjusted equal to the amplitude of the grid voltage. To set the generator frequency equal to the grid one, the turbine pitch angle controller accelerates the turbine/generator until it reaches the synchronous speed. A slight difference of stator and grid frequencies may cause the large phase difference between the two voltages. To compensate for this phase difference, a PLL algorithm is used. After the synchronization is achieved, the generator is connected to the grid and is controlled to extract the maximum power. The effectiveness of the proposed synchronization algorithm is verified by simulation results using PSCAD.

关键词： Wind energy synchronization DFIG PSCAD.

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Initial Stability Study of Calcium Phosphate Coated Dental Implants

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Journal of Wuhan univ.rsity of Technology(Materials Science) 2005年第B12期20卷 246-248页

作者： Changkook YOU In-sung YEO Tae-kwan EOM M W AHN Sukyoung KIM School of Materials Sci. & eng. Yeungnam University Gyeongbuk 712-749 Korea Department of Dentistry Special War Command Seoul 138-110 Korea R&D Center Osstem Co. Ltd. Yeonsan-Gu Busan 611-073 Korea dept.of Orthopedic Surgery College of Medicine Yeungnam Univ. Daegu Korea

Thin film of biodegradable calcium phosphate coated on threaded commercially pure titanium （ cp- Ti ） dental implants has been investigated as one of alternatives to eliminate the problem of the long- term instability of plasma sprayed HA coated implants. In order to compare in-vivo bone-to-implant response behavior among as-machined, HA coated and CMP coated groups, each group was implanted into New Zealand white mature male rabbits for 2 and 6 weeks, and then in-vivo biological behavior was examined in terms of H＆E staining. Initial stability and removable torques of implants were compared among three groups. Measured removable torque of CMP coated specimen at 6 weeks after inplantation was significantly higher than that of non-coated group, but slightly lower than that of HA coated group, without any inflammatory response at the surrounding of the implants. The initial stability （ ISQ value ; implant stability quotient ） of CMP coated specimen at 2 weeks after implantation was slightly lower than that of HA coated group and significantly higher than that of non-coated group. However, after 6 weeks, ISQ value of CMP coated group was slightly higher than that of HA coated group and significantly higher than that of non-coated group.

关键词： calcium metaphosphate initial stability RFA ISQ value osseointegration

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Influence of land use change on the waterbird community of Sihwa Lake,Republic of Korea

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Avian Research 2020年第3期11卷 349-362页

作者： Eunjae Lee Junghee Sagong Yohan Lee Urban Planning Research Division Daejeon Sejong Research InstituteDaejeonRepublic of Korea dept.of Spatial&Environmental Planning Chungnam InstituteGongjuRepublic of Korea Department of Forest Resources and Landscape Architecture Yeungnam UniversityGyeongsanRepublic of Korea

Background:Land use and development alter mudflat and wetland habitat availability,although mudflats and wetlands provide important stopover habitats for shorebirds during the spring and autumn migrations and support communities of ducks and geese during the winter months in the Republic of *** study investigated land use changes around Sihwa Lake(Republic of Korea)and evaluated the effect of these changes on waterbird community ***:We conducted a land-use-change analysis at the medium-resolution level using land cover maps for 2001,2007,2009,and ***,a tidal stream survey was conducted in Sihwa Lake and the surrounding reclaimed mudflats every season for 10 years(2003-2012)to identify the seasonal and interannual variations in waterbird species *** determine the total annual waterbird species and population counts,species diversity index,and interspecies variations,a TRIM(trends and indices for monitoring data)analysis was ***:Wetland area decreased more than 10%while agricultural land,barren land,and grassland area increased more than 10%due to continuous reclamation activities around Sihwa *** land later turned into agricultural land or other land ***-three species and 566,623 individuals were *** number of species,population size,and species diversity index by year and by species showed decreasing trends that were more marked in spring and ***,seasonal and annual variations in waterbird species composition showed decreasing trends in dabbling ducks,herons,grebes,and shorebirds but diving ducks displayed increasing *** particular,shorebirds were reduced to a greater extent than other waterbird species because of the reduction and simplification of the intertidal zone,and shallow waters caused by reclamation and road ***:Increased development and construction around Sihwa Lake has altered migratory shorebird populations with a general decline in spe

关键词： Land use development Migratory bird populations Population trends Waterbird population size

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Importance of the climatical and environmental factors on the grass-land ecosystem in Duo Lun（Nei Meng Gu）:Comparison between the semi-desert region and marine water mass

Importance of the climatical and environmental factors on th...

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2004中国植物生理生态学学术研讨会

作者： Kim Ki-Tai dept.of Biology Yeungnam UniversityGyongsan 712-749Korea.Dept.of Plant Biology and EcologyNankai UniversityTianjin 300071China.

＜正＞ This note on two quite different ecosystems is to be related with grass land and marine water mass. The principal factors in terrestrial ecology are as follows : climatical parameters : solar-radiation, air-temperature, evaporation, precipitation, direction and strength of winds, cloud-capped ratio;soil characteristics : size of soil grains, pH, water content;nutrients : phosphates （P-PO4）, nitrates （N-NO3）, nitrites （N-NO2）, ammonia （N-NH4）, etc. It is necessary to study the seasonal and annual variations of all the above parameters.

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Early spring Vegetation of Duo Lun,Nei Meng Gu and the Ecological Map between Duo Lun and Beijing.

Early spring Vegetation of Duo Lun,Nei Meng Gu and the Ecolo...

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2004中国植物生理生态学学术研讨会

作者： Kim Ki-Tai dept.of biology Yeungnam UniversityGyongsan 712-749Korea.Dept.of Plant Biology and EcologyNankai UniversityTianjin 300071China.

From May 1st 2004 to May 3th a vegetation survey of Duo Lun, Nei Meng Gu was carried out. Duo Lun is situated at 41ooooooooooooo45 ’-42oooooooooo39’ N and 115°30 ’-116°55 ’ E. Annual average air temperature is about 3.5→. This region neighbors the Gobi Desert and has a polar climate. The cold of late winter continues till the end of April. The climatical spring season comes more one month late. So May may be in the beginning of *** average precipitation is about 255.2mm, but annual average evaporation is about 1738.8mm, therefore evaporation is about 7 fold stronger than precipitation.

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E-Beam Graft Polymerization of Hydrophilic PEG-Methacrylate on the Surface of PMMA

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Journal of Surface engineered Materials and Advanced Technology 2012年第4期2卷 264-270页

作者： Seong-Cheol Kim PilHo Huh dept. Nano Medical and Polymer Materials Yeungnam Univeristy 280 Daehak-Ro Gyeongsan Gyeongbuk Republic of Korea Samsung Electronics Co. Ltd. Solar Energy R&D Center San #24 Nongseo-Dong Giheung-Gu Yongin-City Gyeonggi-Do Republic of Korea

The graft polymerization of hydrophilic monomers on the surface of hydrophobic PMMA was performed using an electron beam (e-beam). The dose of e-beam irradiation, reaction concentration, temperature, and reaction time were used to study the effect of variables on the graft density of poly (ethylene glycol)-methacrylate. The results demonstrated that the weight percentage of graft polymer increased with increasing temperature, time and monomer concentration. However, the weight of the graft polymer did not increase with the increasing dose of e-beam irradiation. The change of the contact angle of the water droplet on the PMMA surface was monitored as a function of a reaction time. The results showed that the contact angle decreased up until a specific time and then leveled off to an approximately constant value after a certain reaction time of the graft polymerization. Transmission electron microscopy proved that the constant value of the contact angle was due to the local survival of surface radicals followed by the perpendicular diffusion of monomers only into the bulk of the surface-modified area on the sheet surface.

关键词： Electron Beam Surface Graft Contact Angle ATR TEM

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