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Fault area estimation using traveling wave for wide area protection

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Journal of Modern Power Systems and Clean Energy 2016年第3期4卷 478-486页

作者： Jae-won LEE won-ki kim Joon HAN won-Hyeok JANG Chul-Hwan kim Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwonRepublic of Korea Daewoo Shipbuilding&Marine Engineering Co. Ltd.GeojeRepublic of Korea Electrical and Computer Engineering Department University of Illinois at Urbana-ChampaignChampaignILUSA

As the increasing number of Phasor Measurement Units(PMUs) are deployed, wide area protection in power systems has been gaining interest. In particular, fault detection, fault classification and fault area estimation are essential to reduce the damage of faults, and even prevent catastrophic cascades of failures. In this paper, we present a scheme for fault area estimation using PMUs and traveling wave theory. The purpose of this paper is to formulate a scheme for fault area estimation by calculating the approximate fault location based on traveling wave *** research has targeted at reliable operation of wide transmission system through the estimation of fault *** verify the suggested scheme, the various simulations are performed in practical Korean power transmission *** simulation results show that the proposed scheme has a good performance with high accuracy for estimating fault area.

关键词： Fault area estimation Phasor measurement unit(PMU) Transmission line system Traveling wave Wide area protection

Gas Sensing Characteristics of SnO_2 Whiskers Prepared from SNC_2O_4

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稀有金属材料与工程 2006年第A3期35卷 100-103页

作者： ki-won kim Pyeong-Seok Cho Jong-Heun Lee Seong-Hyeon Hong Department of Materials Science & Engineering Korea UniversitySeoui 136-713Korea School of Materials Science and Engineering and Nano Systems Institute-National Core Research Center Seoul National UniversitySeoul 151-744Korea

SnO_2 whiskers were prepared from the decomposition of whisker-like SnC_2O_4,which was precipitated by a reaction between an aqueous SnCl_2 and oxalic acid solution at high solution temperatures (80℃).After the decomposition of SnC_2O_4 at 450℃,SnO_2 whiskers containing both of rutile and metastable orthorhombic phases were obtained with the content of the orthorhombic phase decreasing with increasing heat-treatment temperature and *** effect of orthorhombic phase upon CO gas sensitivity was investigated by measuring the evolution of the primary particle size and the CO sensitivity with repeating heat treatment at 450℃.The 50μg/g CO sensitivity increased with decreasing concentration of the orthorhombic phase despite particle coarsening,which suggests that the orthorhombic phase is detrimental to the CO gas sensitivity.

关键词： SnO2 whisker orthorhombic phase gas sensor SnC2O4

Growth and Magnetic Properties of Sol-Gel Derived Co-Doped ZnO Thin Film

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Journal of Rare Earths 2006年第Z1期24卷 59-63页

作者： Young Sung kim ki Chul kim won Pil Tae Dae Ho Yoon Tae Seok Park Su Jeong Suh Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea Cambridge-ETRI Joint R&D Centre Electronics and Telecommunications Research Institute Daejeon 305-350 Korea Ulsan Industry Promotion Techno Park Ulsan 683-804 Korea Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea

Zn1-xCoxO films were grown on glass by sol-gel spin coating process. A homogeneous and stable Zn1-xCoxO sol was prepared by dissolving zinc acetate dihydrate, cobalt acetate tetrahydrate and aluminium chloride hexahydrate as solutes in solution of isopropanol and monoethanolamine. The films were postheated and vacuum annealed, and investigated for c-axis preferred orientation and electromagnetic properties. Zn1-xCoxO films with different Co concentrations were oriented well along the c-axis, especially the Zn1-xCoxO film with 10% Co(atom fraction) was highly c-axis oriented. The transmittance spectra show that Zn1-xCoxO films occur d-d transition and sp-d exchange interaction between Co2+ ions. The electrical resistivity of the films at 10% Co had the lowest value because the crystallite size became largest and the crystallinity of the c-axis was improved. X-ray photoelectron spectroscopy and alternating gradient magnetometer analyses indicated that no Co metal cluster was formed, and the ferromagnetism at room temperature appeared. The characteristics of the electrical resistivity and room temperature ferromagnetism of sol-gel derived Zn1-xCoxO films suggest a potential application of dilute magnetic semiconductor devices.

关键词： sol-gel Zn1-xCoxO thin film dilute magnetic semiconductor (DMS)

Segmental artery injury during transforaminal percutaneous endoscopic lumbar discectomy:Two case reports

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World Journal of Clinical Cases 2022年第33期10卷 12345-12351页

作者： Wan-Jae Cho ki-won kim Hyung-Youl Park Bo-Hyoung kim Jun-Seok Lee Department of Orthopedic Surgery Yeouido St.Mary’s HospitalCollege of MedicineCatholic University of KoreaSeoul 07345South Korea Department of Orthopedic Surgery Eunpyeong St.Mary’s HospitalCollege of MedicineCatholic University of KoreaSeoul 03312South Korea

BACKGROUND Since Kambin experimentally induced arthroscopy to treat herniated nucleus pulposus,percutaneous endoscopic lumbar discectomy(PELD)has been *** branch of the segmental artery around the neural foramen may be damaged during PELD using the transforaminal *** report 2 rare cases in which segmental artery injury that occurred during PELD was treated with emergency *** SUMMARY In case 1,a 31-year-old man was transferred to our emergency department with left lower quadrant abdominal pain after PELD at a local *** spine magnetic resonance imaging after the surgery showed a hematoma of the left retroperitoneal area and the psoas muscle *** suspicion of vascular injury,arteriography was *** and blood leakage from the left 4th lumbar segmental artery into the abdominal cavity were *** transarterial embolization was performed using fibered microcoils for bleeding of the segmental *** case 2,a 75-year-old woman was transferred to our emergency department with low blood pressure,right flank pain,and drowsy mental status after PELD at a local *** the patient arrived at the emergency room,the blood pressure decreased from 107/55 mmHg to 72/47 *** blood pressure *** suspicion of vessel injury,arteriography was performed,and the right 4th lumbar segmental artery rupture was *** transarterial embolization was performed for bleeding of segmental *** We were able to find the bleeding focus by angiography and treat the injury of the segmental artery successfully through emergency transarterial embolization.

关键词： Percutaneous endoscopic lumbar discectomy Segmental artery injury Transarterial embolization Angiography Case report

Performance and genetic diversity of 23 provenances of northern red oak(Quercus rubra L.)after 25 years of growth in South Korea

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Journal of Forestry Research 2021年第5期32卷 2181-2188页

作者： ki-won kim Kyoung-Mi Lee Soon-Ho Kwon Ji-Min Park Yang-Gil kim Hye-In Kang Da-Bin Yum Kyu-Suk Kang Department of Agriculture Forestry and BioresourcesSeoul National UniversitySeoul 08826Republic of Korea Department of Forest Bioresources National Institute of Forest ScienceSuwon 16631Republic of Korea Department of Plant Resource Research Korea National ArboretumPocheon 11186Republic of Korea Research Institute of Agriculture and Life Sciences CALS_SNUSeoul 08826Republic of Korea

Growth traits and genetic diversity of 23 provenances of Quercus rubra introduced from North America were analyzed in a provenance trial established with a randomized block design in Hwaseong,Gyeonggi,South Korea in *** variables and survival at age 25 were compared with results from early ***,DBH,volume and stem straightness of *** was better than those of the domestic oak(Quercus accutissima).Growth of the Dunham Island provenance from New York was the best among the 23 provenances that of the Eagle River provenance from Wisconsin was *** rate at age25 was on average 52%.The longitude of seed origin and growth of provenance were consistently significantly negatively correlated at all *** of coastal provenances was superior to that of the inland provenances,which were separated by the Appalachian *** diversity and genetic distance among the provenances were evaluated using micro satellite *** allelic frequencies showed high polymorphism in 10 microsatellite loci,and 292 alleles were *** 10 loci,two were commonly found in the 23 *** mean allelic diversity and heterozygosity observed among the provenances were similar to those from the native populations of *** in North ***’s genetic distance among the 23 was estimated and showed that a clear trend between geographic and genetic distances,indicating that some provenances have high genetic diversity with superior growth performance.

关键词： Introduction breeding Provenance test Adaptation Microsatellite marker Genetic distance

Improved Cycle Properties of FeS_2 Cathode Material with Metallic Additives

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材料科学与工程学报 2007年第6期25卷 910-913页

作者： Jae-won Choi Jae-Kwang kim Gouri Cheruvally Jou-Hyeon Ahn ki-won kim Hyo-Jun Ahn Dong-Kyu Park Department of Chemical & Biological Engineering and Engineering Research Institute Gyeongsang National University900 Gajwa-dongJinju660-701Korea School of Nano and Advanced Materials Engineering and Engineering Research Institute Gyeongsang National University900 Gajwa-dongJinju660-701Korea Kaya Advanced Material Art Inc. Baekrok-Ri 1010-1Yangsan 626-862Korea

Iron disulfide(FeS_2)cathode active material was prepared from iron and sulfur at room temperature by high energy mechanical *** FeS_2 composites containing Co or Ni transition metal powders as additives were also prepared by the same *** cells with these FeS_2 cathodes were studied for charge-discharge properties at room temperature using 0.5M LiTFSI in tetra(ethylene glycol)dimethyl ether(TEGDME)*** voltammetry showed two anodic oxidation peaks at 1.8 and 2.5V and two cathodic reduction peaks at 2.0 and 1.3 V for FeS_2 with metal *** addition of 5wt% Co and 3wt% Ni resulted in an enhancement of the first discharge capacity giving 571 and 844mAh/g respectively at *** cycle performance was also enhanced remarkably by the addition of these electrically conductive transition metals in the active ***_2 with 5wt% Co exhibited a stable cycle performance delivering a reversible capacity of 338mAh/g(37.8% of theoretical capacity)after 20 cycles.

关键词：阴极材料二硫化铁锂离子电池循环性能

Electrochemical Intercalation of Sodium into Silicon Thin Film

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材料科学与工程学报 2008年第1期26卷 141-144页

作者： Dong-Yeon kim Hyo-Jun Ahn Gyu-Bong Cho Jong-Seon kim Ho-Suk Ryu ki-won kim Jou-Hyeon Ahn won-Cheol Shin I-cube center nano advanced materials Engineering Gyeongsang National Uhiversity Jinju 660-701 Korea Department of Chemical ＆ Biological Engineering Gyeongsang National University J inju 660-701 Korea INOSTEK Inc Gyeonggi Technopark 1271-11 Sal-dong Sangnok-gu Ansan-si Gyeonggi-do 426-901 Korea

In order to investigate the possibility of Si thin film as an anode for Na battery,we studied the electrochemical intercalation of sodium into the Si *** Si thin film electrode was prepared using DC magnetron *** ion could intercalate into Si thin film upto Na0.52Si,i.e.530mAh·*** first discharge capacity was 80mAh·g-1-Si,which meant reversible amount of sodium *** discharge capacity slightly decreased to 70mAh·g-1-Si after 10 cycles.

关键词：钠插层反应电池硅薄膜电极直流电磁控溅射

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

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材料科学与工程学报 2007年第6期25卷 886-891页

作者： Kyo-Hong CHOI Kwon-Koo CHO Gyu-Bong CHO Hyo-Jun AHN ki-won kim Yoo-Young kim School of Nano & Advanced Materials Engineering ERI & i-cube centerGyeongsang National University900 GazwadongJinjuGyeongnam 660-701Korea Dept.of Mechanical Engineering Jinju National UniversityJinjuKorea

Several researches have been reported about the characteristic of β-Ga_2O_3 nanowires which was synthesized on nickel oxide *** indeed,recent researches about synthesis of β-Ga_2O_3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide *** this work,Gallium oxide(β-Ga_2O_3)nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700-1000℃ using the iron,nickel,copper,cobalt and zinc oxide as a catalyst,*** β-Ga_2O_3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850,900 and 950℃ in all the *** optimum experimental condition in synthesis of nanowires varied with the kind of *** increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods,and its diameter *** these results,we could be proposed that the growth mechanism of β-Ga_2O_3 nanowires was changed with synthesis temperature of *** and morphology of Synthesized nanowire was characterized by HR-TEM,FE-SEM,EDX and XRD.

关键词：金属纳米粒子显微结构镓氧化物形态学

Liquid crystal-powered Mie resonators for electrically tunable photorealistic color gradients and dark blacks

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Light(Science & Applications) 2022年第6期11卷 1098-1108页

作者： Trevon Badloe Joohoon kim Inki kim won-Sik kim Wook Sung kim Young-ki kim Junsuk Rho Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Biophysics Institute of Quantum BiophysicsSungkyunkwan UniversitySuwon 16419Republic of Korea Department of Intelligent Precision Healthcare Convergence Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics Pohang 37673Republic of Korea National Institute of Nanomaterials Technology(NINT) Pohang 37673Republic of Korea

Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution *** plasmonic and dielectric materials have been employed to produce static colors that fulfil the required criteria for high-performance color printing,however,for practical applications in dynamic situations,a form of tunability is *** of the additive color palette of red,green,and blue enable the expression of further colors beyond the three primary colors,while the simultaneous intensity modulation allows access to the full color ***,we demonstrate an electrically tunable metasurface that can represent saturated red,green,and blue pixels that can be dynamically and continuously controlled between on and off states using liquid *** use this to experimentally realize ultrahigh-resolution color printing,active multicolor cryptographic applications,and tunable pixels toward high-performance full-color reflective displays.

关键词： saturated printing colors