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Arterial stiffness expressed as brachial–ankle pulse wave velocity and gait assessment independent of lower extremity strength:a cross-sectional study in the older men population

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Journal of Geriatric Cardiology 2023年第2期20卷 91-99页

作者： Tae Kyung Yoo Seunghee lee Sae-jong Park jong-Young lee Department of Medicine MetroWest Medical CenterFraminghamUSA Department of Physical Education Korea UniversitySeoulSouth Korea Division of Sports Science Korea Institute of Sport ScienceSeoulSouth Korea Division of Cardiology Department of Internal MedicineKangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoulSouth Korea

BACKGROUND Older men are more vulnerable to fatal falls than women,and gait disturbances contribute to the risk of *** have assessed the association between arterial stiffness and gait dysfunction,but the results have been *** study aimed to conduct a cross-sectional analysis to evaluate the association between brachial–ankle pulse wave velocity(baPWV)and gait assessment in older *** Data from the 2014–2015 Korea Institute of Sport Science Fitness Standards project were used for the *** inclusion criteria were men aged>65 years with gait assessment[the 30-s chair stand test(30s-CST),the timed up and go(TUG)test,the figure-of-8 walk(F8W)test,the 2-min step test(2MST),and the 6-min walk test(6MWT)]and baPWV measurement *** linear regression analysis was conducted with multiple confounding factor adjustments,including lower extremity isometric *** A total of 291 participants were included in the *** mean age was 71.38±4.40 *** mean values were as follows:(1)30s-CST,17.48±5.00;(2)TUG test,6.01±1.10 s;(3)F8W test,25.65±4.71 s;(4)2MST,102.40±18.83 per 2 min;and(5)6MWT,500.02±85.65 *** multivariable adjustment,baPWV was associated with the 6MWT(β=−0.037,95%CI:−0.072–−0.002),TUG test(β=0,95%CI:0.000–0.001),and F8W test(β=0.002,95%CI:0.000–0.004).baPWV was not associated with the 30s-CST and *** The current study showed a statistically significant association between gait assessments and arterial stiffness,independent of lower extremity ***,this association was *** prospective studies are needed to elucidate the complex relationship between arterial stiffness and gait dysfunction.

关键词： stiffness sectional pulse

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Development of temperature-robust damage factor based on sensor fusion for a wind turbine structure

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Frontiers of Structural and Civil Engineering 2015年第1期9卷 42-47页

作者： jong-Woong PARK Sung-Han SIM Jin-hak YI Hyung-Jo JUNG Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA School of Urban and Environmental Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan 689- 798Republic of Korea Coastal Development & Ocean Engineering Research Division Korea Institute of Ocean Science and Technology Ansan 426-744Republic of Korea Department of Civil and Environmental Engineering KAIST Daejeon 305-701 Republic of Korea

Wind power systems have gained much attention due to the relatively high reliability, maturity in technology and cost competitiveness compared to other renewable alternatives. Advances have been made to increase the power efficiency of the wind turbines while less attention has been focused on structural integrity assessment of the structural systems. Vibration-based damage detection has widely been researched to identify damages on a structure based on change in d^mmic characteristics. Widely spread methods are natural frequency-based, mode shape-based, and curvature mode shape-based methods. The natural frequency-based methods are convenient but vulnerable to environmental temperature variation which degrades damage detection capability; mode shapes are less influenced by temperature variation and able to locate damage but requires extensive sensor instrumentation which is costly and vulnerable to signal noises. This study proposes novelty of damage factor based on sensor fusion to exclude effect of temperature variation. The combined use of an accelerometer and an inclinometer was considered and damage factor was defined as a change in relationship between those two measurements. The advantages of the proposed method are： 1） requirement of small number of sensor, 2） robusmess to change in temperature and signal noise and 3） ability to roughly locate damage. Validation of the proposed method is carried out through numerical simulation on a simplified 5 MW wind turbine model.

关键词： sensor fusion damage detection structural health monitoring

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Nielsen type numbers and homotopy minimal periods for maps on the 3-nilmanifolds

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Science China Mathematics 2008年第3期51卷 351-360页

作者： jong Bum lee Department of Mathematics Sogang University Seoul 121-742 Korea

For all continuous maps on the 3-nilmanifolds, we give explicit formulae for a complete computation of the Nielsen type numbers NP_n(f)and Nφ_n(f). The most general cases were explored by Heath and Keppelmann and the complementary part is studied in this paper. While studying the homotopy minimal periods of all maps on the 3-nilmanifolds, we also give a complete description of the homotopy minimal periods for all maps on the 3-nilmanifolds, including a correction to Jezierski and Marzantowicz’s result.

关键词： homotopy minimal period Nielsen number Nielsen type number nilmanifold 55M20 57S30

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Si nanomebranes: Material properties and applications

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Nano Research 2021年第9期14卷 3010-3032页

作者： Arijit Sarkar Yongjun lee jong-Hyun Ahn School of Electrical and Electronic Engineering Yonsei University50 Yonsei-roSeoul 03722Republic of Korea

Silicon(Si)has widely been used as an essential material in the modern semiconductor ***,new attempts have been actively made to apply Si to a variety of fields such as flexible electronic devices and biosensors by manufacturing Si nanomembranes(NMs)having nanometer *** particular,as the thickness of Si is reduced to a nanometer scale,its mechanical,electrical,and optical properties differ from that of its bulk form,which provides opportunities for the development of new conceptual *** this review,we present recent advances in Si NM technology that exhibit functional features different from the bulk *** addition,we discuss the opportunities and current challenges related to this field.

关键词： Si nanomebranes flexible electronics bio-integrated electronics Si optoelectronics strain engineering

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Effects of surface roughness on bending properties of rolled AZ31 alloy

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Journal of Magnesium and Alloys 2023年第4期11卷 1224-1235页

作者： Gyo Myeong lee jong Un lee Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigated the effects of mechanical-polishing-induced surface roughness and the direction of polishing lines on the bending properties of a rolled AZ31 *** this end,three-point bending tests were performed on one sample without polishing lines(SS sample)and two samples with polishing lines—one in which the polishing lines were parallel to the rolling direction(RS-RD sample)and the other in which they were parallel to the transverse direction(RS-TD sample).In all three samples,macrocracks were formed in the width direction on the outer surface,where tensile stress was predominantly generated in the longitudinal ***,the macrocracks formed in the SS sample were curved because of the merging of uniformly formed fine microcracks,whereas those formed in the RS-TD sample were linear owing to the formation of relatively coarse microcracks along the polishing *** bendability of the samples was in the order of SS>RS-RD>RS-TD,and their limiting bending depths were 4.8,4.6,and 4.4 mm,*** the presence of mechanical-polishing-induced surface roughness,polishing lines perpendicular to the direction of the major stress(i.e.,tensile stress along the longitudinal direction)resulted in a greater degree of stress concentration on the outer surface of the bending *** higher stress concentration promoted the formation of undesirable{10–11}contraction and{10–11}–{10–12}double twins—which typically act as crack initiation sites—and thereby facilitated crack generation and ***,the surface roughness caused premature fracture during bending deformation,which,in turn,caused deterioration of the bendability of the rolled Mg alloy.

关键词： AZ31 alloy Bending Surface roughness Stress concentration Crack

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Bending properties of extruded AZ91–0.9Ca–0.6Y alloy and their improvement through precompression and annealing

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Journal of Magnesium and Alloys 2022年第8期10卷 2238-2251页

作者： jong Un lee Gyo Myeong lee Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

In this study,an extruded Mg–9Al–1Zn–0.3Mn–0.9Ca–0.6Y(AZXW9110)alloy is subjected to precompression and subsequent annealing(PCA)treatment for improving its bending formability,and the three-point bending properties of the as-extruded material and the precompressed and subsequently annealed(PCAed)material at room temperature are *** bending,microcracks formed in undissolved Al2Ca,Al2Y,and Al8Mn4Y particles propagate along the grain boundaries or twin boundaries and consequently form a macrocrack in the tension zones of the bending samples of both the ***,the bending formability of the PCAed material is 75%higher than that of the as-extruded material owing to the promoted twinning and slip behaviors in the *** as-extruded material has a strong normal direction(ND)texture and a weak transverse direction(TD)texture,and the ND-and TD-oriented grains are unfavorable for both{10–12}twinning and basal slip in the tension zone of the bending sample of this material,which eventually results in its low bending *** PCAed material has a strong extrusion direction(ED)texture,weak TD texture,and spread ND *** bending,{10–12}twins are fully formed in the ED-oriented grains,and this{10–12}twinning effectively accommodates the plastic strain in the tension *** addition,the activation of basal slip in the ND-oriented grains of the PCAed material is promoted owing to the spread ND texture of this ***,this material exhibits substantially superior bending formability because of the vigorous{10–12}twinning in its ED-oriented grains and promoted basal slip in its ND-oriented grains.

关键词： Magnesium Bending Formability Twinning Texture

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Enhanced KOCED Routing Protocol with K-means Algorithm

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Computers, Materials & Continua 2021年第6期67卷 4019-4037页

作者： SeaYoung Park jong-Yong lee Daesung lee Department of Plasma Bioscience and Display KwangWoon University Graduate SchoolSeoul01897Korea Ingenium College of Liberal Arts KwangWoon UniversitySeoulKorea Department of Computer Engineering Catholic University of PusanBusanKorea

Replacing or recharging batteries in the sensor nodes of a wireless sensor network(WSN)is a significant ***,efficient power utilization by sensors is a critical requirement,and it is closely related to the life span of the *** a sensor node consumes all its energy,it will no longer function ***,various protocols have been proposed to minimize the energy consumption of sensors and thus prolong the network ***,clustering algorithms combined with artificial intelligence have been proposed for this *** particular,various protocols employ the K-means clustering algorithm,which is a machine learning *** number of clustering configurations required by the K-means clustering algorithm is greater than that required by the hierarchical ***,the selection of the cluster heads considers only the residual energy of the nodes without accounting for the transmission distance to the base *** terms of energy consumption,the residual energy of each node,the transmission distance,the cluster head location,and the central relative position within the cluster should be considered *** this paper,we propose the KOCED(K-means with Optimal clustering for WSN considering Centrality,Energy,and Distance)protocol,which considers the residual energy of nodes as well as the distances to the central point of the cluster and the base station.A performance comparison shows that the KOCED protocol outperforms the LEACH protocol by 259%(223 rounds)for first node dead(FND)and 164%(280 rounds)with 80%alive nodes.

关键词： WSN routing protocol K-means K-optimal LEACH KCE KOCED

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Permeability evaluation for artificial single rock fracture according to geometric aperture variation using electrical resistivity

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第4期13卷 787-797页

作者： Hangbok lee jong-Won lee Tae-Min Oh Deep Subsurface Research Center Korea Institute of Geoscience and Mineral ResourcesDaejeon34132Republic of Korea Department of Civil and Environmental Engineering Pusan National UniversityBusan46241Republic of Korea

A convenient approach was proposed by which to evaluate and monitor the permeability of a rock fracture by verifying the quantitative correlation between the electrical resistivity and permeability at laboratory *** this purpose,an electrical resistivity measurement system was applied to the laboratory experiments using artificial cells with the shape of a single rock *** experiments were conducted using rock fractures according to the geometry,aperture sizes,wavelengths,and roughness *** overall negative relationship between the normalized electrical resistivity values and the aperture sizes directly linked with the permeability,was well fitted by the power-law function with a large determination coefficient(≈0.86).The effects of wavelength and roughness amplitude of the rock fracture on the electrical resistivity were also *** showed that the electrical resistivity was slightly increased with decreasing wavelength and increasing roughness *** empirical model for evaluating the permeability of a rock fracture was proposed based on the experimental *** the field,if the electrical resistivity of pore groundwater could be measured in advance,this empirical model could be applied effectively for simple,quick monitoring of the fracture *** uncertainty may be associated with the permeability estimation due to the limited control parameters considered in this research,this electrical resistivity approach could be helpful to monitor the rock permeability in deep underground facilities such as those used for radioactive waste repositories or forms of energy storage.

关键词： Permeability Rock fracture Electrical resistivity Fracture geometry Long-term monitoring

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Synthesis of tin nanoparticles through modified polyol process and effects of centrifuging and drying on nanoparticles

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中国有色金属学会会刊：英文版 2012年第S3期22卷 707-711页

作者： Sang-Soo CHEE jong-Hyun lee Department of Materials Science and Engineering Seoul National University of Science and Technology

Sn nanoparticles with average diameter of 13.1 nm were synthesized by modified polyol process,and their melting point was observed to be about 40 °C less than that of bulk *** though Sn nanoparticles are solid and covered with thin PVP capping and oxide layer,Sn nanoparticles in solution agglomerate upon centrifugation,resulting in a melting point *** to stickiness of the PVP capping layer,extensive aggregation between Sn nanoparticles was observed after ***,the aggregation behavior did not further influence the melting point,because actual agglomeration did not occur in the aggregates.

关键词： tin nanoparticle melting point centrifugation agglomeration aggregation

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Nielsen coincidence theory on infra-solvmanifolds of Sol

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Science China Mathematics 2021年第8期64卷 1861-1884页

作者： jong Bum lee Karen Regina Panzarin Department of Mathematics Sogang UniversitySeoul 121-742Korea Departamento de Matematica Universidade Federal de Sao CarlosSao CarlosSP 13565-905Brazil

We derive averaging formulas for the Lefschetz coincidence numbers,the Nielsen coincidence numbers and the Reidemeister coincidence numbers of maps on infra-solvmanifolds modeled on a connected and simply connected solvable Lie group of type(R).As an application,we compare our formula for the Nielsen coincidence numbers with a result of Jezierski(1992)for pairs of maps on some infra-solvmanifolds of *** all the pairs of self-maps of a nonorientable infra-solvmanifold of Sol,we determine the sets of all the possible values of the Nielsen coincidence numbers and the Reidemeister coincidence numbers.

关键词： averaging formula infra-solvmanifold Lefschetz coincidence number Nielsen coincidence number Reidemeister coincidence number Sol-geometry

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