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Novel ternary metals-based telluride electrocatalyst with synergistic effects of high valence non-3d metal and oxophilic Te for pH-universal hydrogen evolution reaction

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Journal of Energy Chemistry 2023年第5期80卷 736-743,I0015页

作者： Seunghwan Jo Wenxiang Liu Yanan Yue Ki Hoon Shin keon beom lee Hyeonggeun Choi Bo Hou Jung Inn Sohn Division of Physics and Semiconductor Science Dongguk UniversitySeoul 04620Republic of Korea School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072HubeiChina School of Physics and Astronomy Cardiff UniversityCardiff CF243AAWalesUK

Electrocatalyst designs based on oxophilic foreign atoms are considered a promising approach for developing efficient pH-universal hydrogen evolution reaction(HER)electrocatalysts by overcoming the sluggish alkaline HER ***,we design ternary transition metals-based nickel telluride(Mo WNi Te)catalysts consisting of high valence non-3d Mo and W metals and oxophilic Te as a first demonstration of non-precious heterogeneous electrocatalysts following the bifunctional *** Mo WNi Te showed excellent HER catalytic performance with overpotentials of 72,125,and 182 mV to reach the current densities of 10,100,and 1000 mA cm^(-2),respectively,and the corresponding Tafel slope of 47,52,and 58 mV dec-1in alkaline media,which is much superior to commercial Pt/***,the HER performance of Mo WNi Te is well maintained up to 3000 h at the current density of 100 mA cm^(-2).It is further demonstrated that the Mo WNi Te exhibits remarkable HER activities with an overpotential of 45 mV(31 mV)and Tafel slope of 60 mV dec-1(34 mV dec-1)at 10 mA cm^(-2)in neutral(acid)*** superior HER performance of Mo WNi Te is attributed to the electronic structure modulation,inducing highly active low valence states by the incorporation of high valence non-3d transition *** is also attributed to the oxophilic effect of Te,accelerating water dissociation kinetics through a bifunctional catalytic mechanism in alkaline *** functional theory calculations further reveal that such synergistic effects lead to reduced free energy for an efficient water dissociation process,resulting in remarkable HER catalytic performances within universal pH environments.

关键词： Telluride catalyst Oxophilic effect High valence non-3d metal Bifunctional mechanism pH-universal hydrogen evolution reaction

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Surface Roughness Evaluation in Dry-Cutting of Magnesium Alloy by Air Pressure Coolant

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Engineering（科研） 2010年第10期2卷 788-792页

作者： Jeong-Du Kim keon-beom lee 不详

In this paper, a studying of surface roughness in dry milling with air pressure coolant of wrought magnesium alloy AZ31B will be carried out. The effects of air flow, feed-rate per tooth, cutting velocity and number of inserts in a cutting tool on surface roughness have been examined. Surface roughness increases with increasing feed-rate per tooth and increasing number of inserts in the cutting tool. However, it is nearly unchanged under a specific range of cutting velocity in the experiment and improved by the flow of air cooling.

关键词： Machinability Surface Roughness Number of Inserts Dry Milling Air Pressure Coolant

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Model of Rotation Accuracy of High-Speed Spindles on Ball Bearings

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Engineering（科研） 2010年第7期2卷 477-484页

作者： Jeong-Du Kim Igor Zverv keon-beom lee 不详

For the purpose to improve a design quality of high-speed spindle units, we have developed mathematical models and software to simulate a rotation accuracy of spindles running on ball bearings. In order to better understand the mechanics of ball bearings, the dynamic interaction of ball bearings and spindle unit, and the influence of the bearing imperfections on the spindle rotation accuracy, we have carried out computer aided analysis and experimental studies. When doing this, we have found that the spindle rotation accuracy can vary drastically with rotational speed. The influence of bearing preload has a secondary importance. Comparison of the results of these studies has demonstrated adequacy of the models developed to the real spindle units.

关键词： High-Speed Spindle Unit Ball Bearing Bearing Imperfections Spindle Rotation Accuracy

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Thermal Model of High-Speed Spindle Units

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Intelligent Information Management 2010年第5期2卷 306-315页

作者： Jeong-Du Kim Igor Zverv keon-beom lee 不详

For the purpose to facilitate development of high-speed Spindle Units (SUs) running on rolling bearings, we have developed a beam element model, algorithms, and software for computer analysis of thermal characteristics of SUs. The thermal model incorporates a model of heat generation in rolling bearings, a model of heat transfer from bearings, and models for estimation of temperature and temperature deformations of SU elements. We have carried out experimental test and made quantitative evaluation of the effect of operation conditions on friction and thermal characteristics of the SUs of grinding and turning machines of typical structures. It is found that the operation conditions make stronger effect on SU temperatures when rpm increases. A comparison between the results of analysis and experiment proves their good mutual correspondence and allows us to recommend application of the models and software developed for design and research of high-speed SUs running on rolling bearings.

关键词： Thermal Model High-Speed Spindle Unit Rolling Bearing

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Prediction of Monthly Mean Surface Air Temperature in a Region of China

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Advances in Atmospheric Sciences 2007年第3期24卷 503-508页

作者： Jeong-Hyeong lee keon-Tae SOHN Division of Management Information Science Dong-A University Busan 604-714Korea Department of Statistics Pusan National University Busan 609-735Korea

In conventional time series analysis, a process is often modeled as three additive components： linear trend, seasonal effect, and random noise. In this paper, we perform an analysis of surface air temperature in a region of China using a decomposition method in time series analysis. Applications to the National Centers for Environmental Prediction/the National Center for Atmospheric Research （NCEP/NCAR） Collaborative Reanalysis data in this region of China are discussed. The main finding was that the surface air temperature trend estimated for January 1948 to February 2006 was not statistically significant at 0.5904℃ （100 yr）^-1. Forecasting aspects are also considered.

关键词： Chinese region surface air temperature time series decomposition method regression

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Macrophage activation syndrome in children with Kawasaki disease: diagnostic and therapeutic approaches

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World Journal of Pediatrics 2020年第6期16卷 566-574页

作者： Seung beom Han Soo-Young lee Department of Pediatrics Daejeon St.Mary's Hospital.College of MedicineThe Catholic University of Korea64 Daeheung-ro.Jung-guDaejeon 34943Republic of Korea Department of Pediatrics.Bucheon St.Mary's Hospital College of MedicineThe Catholic University of Korea327 Sosa-roWonmi-gu.Bucheon 14647Republic of Korea

Background Macrophage activation syndrome(MAS)is a rare,life-threatening complication of Kawasaki disease(KD).Early recognition and treatment of MAS are very important,but sometimes it is difficult to distinguish MAS from a severe form of *** sources A PubMed search was performed in Clinical Queries using the key terms“macrophage activation syndrome or secondary hemophagocytic lymphohistiocytosis(HLH)”and“Kawasaki disease”.Results KD patients with MAS show high intravenous immunoglobulin(IVIG)resistance and coronary *** is also as high as MAS in other *** fever greater than 10 days is highly associated with development of MAS in *** is observed in more than two-thirds of KD patients with *** is often the earliest laboratory finding of *** is highly specific and sensitive for detecting MAS in KD;so,ferritin levels should be checked if there are unexplained clinical exacerbations in KD *** the under-recognition of MAS in KD,it is prudent to consider resistant KD as occult/subclinical *** KD patients with MAS have good outcomes on immune ***,if KD patients fulfill the HLH-2004 diagnostic criteria,they may undergo longer and more intensive treatment than *** The possible existence of MAS should be taken into account when a KD patient shows persistent fever,splenomegaly,thrombocytopenia,hyperferritinemia,or IVIG *** under-diagnosis of MAS in patients with KD is an important issue to be ***,however,there is a possibility of over-treatment of MAS in patients with KD.

关键词： Macrophage activation syndrome Kawasaki disease Children

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Development of Non-Dissipative Direct Time Integration Method for Structural Dynamics Application

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Computer Modeling in Engineering & Sciences 2019年第1期118卷 41-89页

作者： Sun-beom Kwon Jae-Myung lee Department of Naval Architecture and Ocean Engineering Pusan National UniversityJangjeon-DongGeumjeong-GuBusan 609-735Korea.

A direct time integration scheme based on Gauss-Legendre quadrature is proposed to solve problems in linear structural *** proposed method is a oneparameter non-dissipative *** stability,accuracy,and dispersion characteristics are achieved using appropriate values of the *** proposed scheme has second-order accuracy with and without physical ***,its stability,accuracy,and dispersion are *** addition,its performance is demonstrated by the two-dimensional scalar wave problem,the single-degree-of-freedom problem,two degrees-of-freedom spring system,and beam with boundary *** wave propagation problem is solved in the high frequency wave regime to demonstrate the advantage of the proposed *** the proposed scheme is applied to solve the wave problem,more accurate solutions than those of other methods are obtained by using the appropriate value of the *** the single-degree-offreedom system,two degrees-of-freedom system,and the time responses of beam,the proposed scheme can be used effectively owing to its high accuracy and lower computational cost.

关键词： Structural dynamics finite elements direct time integration Gauss-Legendre quadrature non-dissipative scheme.

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Flexible highly-effective energy harvester via crystallographic and computational control of nanointerfacial morphotropic piezoelectric thin film

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Nano Research 2017年第2期10卷 437-455页

作者： Chang Kyu Jeong Sung beom Cho Jae Hyun Han Dae Yong Park Suyoung Yang Kwi-II Park Jungho Ryu Hoon Sohn Yong-Chae Chung keon Jae lee Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro Yuseong-gu Daejeon 34141 Republic of Korea KAISTInstitute for the NanoCentury (KINC) 291 Daehak-ro Yuseong-gu Daejeon 34141 Republic of Korea Division of Materials Science and Engineering Hanyang University 222 Wangsimni-ro Seongdong-gu Seou104763 Republic of Korea Department of Civil and Environmental Engineering KAIST 291 Daehak-ro Yuseong-gu Daejeon 34141 Republic of Korea Department of Energy Engineering Gyeongnam National University of Science and Technology 33 Dongjin-ro Jinju Gyeongnam 52725 Republic of Korea Functional Ceramic Group Korea Institute of Materials Science (KIMS) 797 Changwon-daero Seongsan-gu Changwon Gyeongnam.51508 Republic of Korea

Controlling the properties of piezoelectric thin films is a key aspect for designing highly efficient flexible electromechanical devices. In this stud）~ the crystallographic phenomena of PbZr1-xTixO3 （PZT） thin films caused by distinguished interfacial effects are deeply investigated by overlooking views, including not only an experimental demonstration but also ab initio modeling. The polymorphic phase balance and crystallinity, as well as the crystal orientation of PZT thin films at the morphotropic phase boundary （MPB）, can be stably modulated using interfacial crystal structures. Here, interactions with MgO stabilize the PZT crystallographic system well and induce the texturing influences, while the PZT film remains quasi-stable on a conventional A1203 wafer. On the basis of this fundamental understanding, a high-output flexible energy harvester is developed using the controlled-PZT system, which shows significantly higher performance than the unmodified PZT generator. The voltage, current, and power densities are improved by 556%, 503%, and 822%, respectively, in comparison with the previous flexional single-crystalline piezoelectric device. Finally, the improved flexible generator is applied to harvest tiny vibrational energy from a real traffic system, and it is used to operate a commercial electronic unit. These results clearly indicate that atomic-scale designs can produce significant impacts on macroscopic applications.

关键词： energy harvesting morphotropic phaseboundary (MPB) piezoelectric first-principles calculation lead zirconium titanate(PZT)

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Statistical Prediction of Heavy Rain in South Korea

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Advances in Atmospheric Sciences 2005年第5期22卷 703-710页

作者： keon Tae SOHN Jeong Hyeong lee Soon Hwan lee Chan Su RYU Pusan National University Busan 609-735 KoreaDong-A University Busan 604-714 Korea Chosun University Gwangju 501-759 KoreaChosun University Gwangju 501-759 Korea

This study is aimed at the development of a statistical model for forecasting heavy rain in South Korea. For the 3-hour weather forecast system, the 10 km×10 km area-mean amount of rainfall at 6 stations （Seoul, Daejeon, Gangreung, （Jwangju, Busan, and Jeju） in South Korea are used. And the corresponding 45 synoptic factors generated by the numerical model are used as potential predictors. Four statistical forecast models （linear regression model, logistic regression model, neural network model and decision tree model） for the occurrence of heavy rain are based on the model output statistics （MOS） method. They are separately estimated by the same training data. The thresholds are considered to forecast the occurrence of heavy rain because the distribution of estimated values that are generated by each model is too skewed. The results of four models are compared via Heidke skill scores. As a result, the logistic regression model is recommended.

关键词： heavy rain model output statistics linear regression logistic regression neural networks,decision tree

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Velocity Profiles between Two Baffles in a Horizontal Circular Tube

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Journal of Thermal Science 2014年第6期23卷 544-551页

作者： Tae-Hyun Chang Hae-Soo lee keon-Je Oh Doeg Hee Doh Chang-Hoan lee Senior Research Fellow of RESEAT Korea Institute of Science and Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University School of Mechanical Engineering Kyungnam University Division of Mechanical and Energy Systems Engineering Korea Marine and Ocean University Korea Institute of Science and Technology Information

The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted *** baffles are also an important element inside the heat *** materials influence the flow pattern in the *** influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular *** velocity of the particles was measured before the baffle and between them in the test *** show that the flows near the front baffle flow were parallel to the vertical wall,and then concentrate on the upper opening of the front *** flows circulate in the front and rear *** flow profiles are related to the Reynolds number(Re) or the flow *** velocity profiles at lower Re number showed a complicated mixing,concentrating on the lower opening of the rear baffle as front *** flow was employed in this study,which was produced using tangential velocities at the *** the entrance of the front baffle,the velocity vector profiles with swirl were much different from that without ***,velocities between two baffles are not much different from those without swirl.

关键词： Baffle Shell and tube Tangential inlet Swirl Particle image velocimetry

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