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ON TRANSMISSION PROBLEM FOR VISCOELASTIC WAVE EQUATION WITH A LOCALIZED A NONLINEAR DISSIPATION

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Acta Mathematica Scientia 2013年第2期33卷 362-374页

作者： Jeong Ja bae Seong Sik KIM Department of Mathematics Dongeui UniversityPusan 614-714Korea

In this article, we consider the global existence and decay rates of solutions for the transmission problem of Kirchhoff type wave equations consisting of two physically different types of materials, one component being a Kirchhoff type wave equation with time dependent localized dissipation which is effective only on a neighborhood of certain part of boundary, while the other being a Kirchhoff type viscoelastic wave equation with nonlinear memory

关键词： Existence of solution uniform decay transmission problem boundary valueproblem localized dissipation

Diversity patterns and phylogenetic structure of vascular plants along elevational gradients in a mountain ecosystem, South Korea

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Journal of Mountain Science 2018年第2期15卷 280-295页

作者： CHUN Jung-Hwa LEE Chang-bae Division of Forest Ecology National Institute of Forest Science Global Resources Division Korea Forestry Promotion Institute

Recently, a phylogenetic diversity and community structure analysis as complementary to species-centric approaches in biodiversity studies provides new insights into the processes of community assembly. In this study, we analyzed species and phylogenetic diversity and community structures for woody and herbaceous plants along two elevational transects on Mt. baekhwa, South Korea. The species richness and phylogenetic diversity of woody plants showed monotonic declining patterns with increasing elevation along all transects, whereas herbaceous plants showed different patterns, such as no relationship and a reversed unimodal pattern, between the study transects. The main drivers of these patterns were climate and habitat variables for woody and herbaceous plants, respectively. In addition, the phylogenetic community structure primarily showed phylogenetic clustering regulated by deterministic processes, especially environmental filtering, such as climate or habitat factors, along the two transects, although herbaceous plants along a transect depicted phylogenetic randomness as a result of a neutral process. Our findings suggest that deterministic and neutral processes may simultaneously control the community structures along small-scale elevational gradients such as local transects, although the deterministic process may be the predominant type.

关键词： Community structure Deterministicprocess Elevational gradient Neutral process Phylogenetic diversity Species richness

Patterns and determinants of plant richness by elevation in a mountain ecosystem in South Korea: area, mid-domain effect,climate and productivity

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Journal of Forestry Research 2015年第4期26卷 905-917页

作者： Chang-bae Lee Jung-Hwa Chun Korea Green Promotion Agency 121 DunsanbukroSeoguDaejeon 302-831Republic of Korea Division of Forest Ecology Korea Forest Research Institute57 HoegiroDongdaemunguSeoul 130-712Republic of Korea

We examined patterns of plant species richness on an elevation gradient and evaluated the effects of cli- matic variables including mean annual temperature and precipitation, area, the mid-domain effect and productivity on species richness along two transects on Mt. Seorak, South Korea. A total of 235 plant species of 72 families and 161 genera were recorded from 130 plots along the two transects. Two different patterns, monotonic decline and a unimodal shape, were observed for woody plants with the change in elevation along the two transects, whereas multimodal patterns were observed for all plant species considered together and for herbaceous plants. Area and productivity showed significant relationships with total plant richness. Climatic variables were better predictors than other variables for variation by elevation in woody plant richness, whereas productivity was a more important variable for herbaceous plant richness. Although area was an important variable for predicting species richness pat- terns, the effects differed by transect and plant group. No empirical evidence was linked to the mid-domain *** elevational patterns may characterize different groups in the same taxon and there might be fundamental differences in the mechanisms underlying these richness patterns.

关键词： Area Climatic variables Elevationalpatterns Plant richness Productivity

A GCM-Based Forecasting Model for the Landfall of Tropical Cyclones in China

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Advances in Atmospheric Sciences 2011年第5期28卷 1049-1055页

作者：孙建奇 Joong bae AHN Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences Beijing 100029 Division of Earth Environmental System Atmospheric SciencesPusan National University Pusan 609735 Korea Division of Earth Environmental System Atmospheric SciencesPusan National UniversityPusan 609735Korea

A statistical dynamic model for forecasting Chinese landfall of tropical cyclones （CLTCs） was developed based on the empirical relationship between the observed CLTC variability and the hindcast atmospheric circulations from the Pusan National University coupled general circulation model （PNU-CGCM）.In the last 31 years,CLTCs have shown strong year-to-year variability,with a maximum frequency in 1994 and a minimum frequency in *** features were well forecasted by the model.A cross-validation test showed that the correlation between the observed index and the forecasted CLTC index was high,with a coefficient of *** relative error percentage （16.3%） and root-mean-square error （1.07） were *** the coupled model performs well in terms of forecasting CLTCs;the model has potential for dynamic forecasting of landfall of tropical cyclones.

关键词： statistical-dynamical model cyclone forecast tropical cyclone coupled model cross validation

Coffee consumption and risk of type 2 diabetes mellitus in Asians:A meta-epidemiological study of population-based cohort studies

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World Journal of Diabetes 2021年第6期12卷 908-915页

作者： Jong-Myon bae Department of Preventive Medicine Jeju National University School of MedicineJeju-si 63243South Korea

BACKGROUND Previous systematic reviews have consistently reported that coffee consumption has a preventive effect on the occurrence of type 2 diabetes mellitus(T2DM).However,further evaluations between coffee consumption and the risk of T2DM in Asian populations are *** To conduct a meta-epidemiological study on systematic reviews evaluating the association between coffee consumption and the risk of T2DM in Asian *** The selection criterion was defined as a population-based prospective cohort study evaluating the association between coffee consumption and the risk of T2DM in Asian populations,reporting the adjusted relative risk(RR)and its 95%confidence interval(CI)for potential confounders.A fixed-effect model metaanalysis was applied to calculate the summary RR and its 95%CI in less than 50%of the I2 value indicating the level of heterogeneity.A two-stage fixed-effects doseresponse meta-analysis(DRMA)was performed to calculate the risk per unit dose(a cup per day).RESULTS A total of seven studies were selected in this meta-epidemiological *** risk of T2DM in Asian populations was significantly reduced in the highest to the lowest dose group(summary RR=0.73,95%CI:0.66-0.82;I2 value=0.0%).The DRMA showed that drinking one cup of coffee per day reduced the risk of T2DM in Asian populations by 8%(RR=0.92,95%CI:0.90-0.95).CONCLUSION These findings support the conclusion that coffee consumption has a protective effect on the occurrence of T2DM in Asian men and women.

关键词： Coffee Diabetes mellitus Cohort studies Meta-analysis Systematic reviews

Effect of friction on the contact stress of a coated polymer gear

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Friction 2020年第6期8卷 1169-1177页

作者： Su-Min bae Kuk-Jin SEO Dae-Eun KIM Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea

Polymer gears are used extensively in various ***,durability issues have been emerging because of friction at gear tooth contact *** extend the lifetime of polymer gears,a low-frictional coating has been considered as a possible *** this study,a finite element simulation method was performed to investigate the contact stress between a pair of coated polymer *** simulation included various friction coefficients(COFs)for studying the effects of friction during the *** results revealed that the friction causes the contact stress to shift over the roll angle,which is attributed to the direction of the sliding friction based on a free-body *** also investigated the effects of coating and found that a thin coating has little effect on the bulk deformation behavior of the ***,the stress distribution in the coating at the pitch point was investigated as the COF *** zero friction,three notable stress regions were observed:1)the center of the surface,2)the end of the contact,and 3)the overall contact *** COF was increased in the micro-slip region of the contact interface,both tensile and compressive stresses in the coating *** study provides significant aid to engineers for understanding the stress response of the coating applied to polymer gears to achieve an optimal design.

关键词： coating contact stress finite element method(FEM) friction polymer gear

Recent progress in quasi-two-dimensional and quantum dot perovskite light-emitting diodes harnessing the diverse effects of ligands:A review

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Nano Research 2022年第7期15卷 6449-6465页

作者： Yurim bae Jun Ryu Saemon Yoon Dong-Won Kang School of Energy Systems Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Smart City Chung-Ang UniversitySeoul 06974Republic of Korea

Halide perovskites have been extensively studied for use as light-emitting diodes(LEDs)in next-generation displays due to their beneficial characteristics,including their high color purity and wide color *** perovskites can be categorized into four representative structures:three-dimensional(3D)bulk,two-dimensional(2D),quasi-two-dimensional(quasi-2D),and quantum dot(QD).Recently,excellent advances in the performance of perovskite LEDs(PeLEDs),especially those with quasi-2D and QD architectures,have been demonstrated with the incorporation of organic chain *** can both modify the structure of PeLEDs,such as forming multi-quantum wells in quasi-2D PeLEDs and essential passivation layers in QD PeLEDs,and also enhance their optical *** appropriate use of ligands in PeLEDs can thus lead to greater luminescence,current efficiency,power efficiency,and external quantum *** this review,the principal roles of ligands in quasi-2D and QD PeLEDs are systematically ***,current limitations and future perspectives are discussed in detail.

关键词： perovskites light emitting diode ligands quasi-two-dimensional(quasi-2D) quantum dot

Gait Optimization of a Quadruped Robot Using Evolutionary Computation

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Journal of Bionic Engineering 2021年第2期18卷 306-318页

作者： Jihoon Kim Dang Xuan Ba Hoyeon Yeom Joonbum bae Mechanical Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919South Korea Automatic Control HoChiMinh City University of Technology and Education(HCMUTE)HoChiMinh City 71307Vietnam

Evolutionary Computation(EC)has strengths in terms of computation for gait ***,conventional evolutionary algorithms use typical gait parameters such as step length and swing height,which limit the trajectory deformation for optimization of the foot ***,the quantitative index of fitness convergence is *** this paper,we perform gait optimization of a quadruped robot using foot placement perturbation based on *** proposed algorithm has an atypical solution search range,which is generated by independent manipulation of each placement that forms the foot trajectory.A convergence index is also introduced to prevent premature cessation of *** conventional algorithm and the proposed algorithm are applied to a quadruped robot;walking performances are then compared by gait *** the two algorithms exhibit similar computation rates,the proposed algorithm shows better fitness and a wider search *** evolutionary tendency of the walking trajectory is analyzed using the optimized results,and the findings provide insight into reliable leg trajectory design.

关键词： bionic robot evolutionary computation genetic algorithm gait optimization parameter perturbation convergence index

Mining fine-grained sequential travel patterns from social geo-tagged photos

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Frontiers of Computer Science 2018年第6期12卷 1255-1257页

作者： Thanh-Hieu BUI Seong-bae PARK Institute of Research and Development Duy Tan UniversityDa Nang 550000Vietnam Department of Computer Science and Engineering Kyung Hee UniversityYongin 17104Korea

A huge amount of geo-tagged photos that contains broad knowledge about travel behaviors of human is generated and posted on social photo-sharing sites. In literature, many studies about mining travel patterns from geo-tagged social photos have been proposed. However, the existing studies lack of a comprehensive system to mine fine-grained travel patterns by utilizing extensions of sequential pattern mining. We consider the following questions for San Francisco City, CA, USA: 1) What are the popular travel routes for tourists if they have only four hours or eight hours for visiting? 2) Which POIs do international tourists prefer to visit after visiting Golden Gate Bridge? 3) Are there any differences in travel behavior between American tourists and international tourists, between male American tourists and female American tourists, between male international tourists and female international tourists? To address these questions, we define and implement a novel framework to mine fine-grained travel patterns from geo-tagged photos of a tourist destination.

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