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Ternary Forecast of Heavy Snowfall in the Honam Area, Korea

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Advances in Atmospheric Sciences 2009年第2期26卷 327-332页

作者： keon Tae SOHN Jeong Hyeong LEE Young Seuk CHO Department of Statistics Pusan National University Division of Management Information Science Dong-A University

The objective of this study is to improve the statistical modeling for the ternary forecast of heavy snowfall in the Honam area in Korea. The ternary forecast of heavy snowfall consists of one of three values, 0 for less than 50 mm, 1 for an advisory （50-150 ram）, and 2 for a warning （more than 150 mm）. For our study, the observed daily snow amounts and the numerical model outputs for 45 synoptic factors at 17 stations in the Honam area during 5 years （2001 to 2005） are used as observations and potential predictors respectively. For statistical modeling and validation, the data set is divided into training data and validation data by cluster analysis. A multi-grade logistic regression model and neural networks are separately applied to generate the probabilities of three categories based on the model output statistic （MOS） method. Two models are estimated by the training data and tested by the validation data. Based on the estimated probabilities, three thresholds are chosen to generate ternary forecasts. The results are summarized in 3 × 3 contingency tables and the results of the three-grade logistic regression model are compared to those of the neural networks model. According to the model training and model validation results, the estimated three-grade logistic regression model is recommended as a ternary forecast model for heavy snowfall in the Honam area.

关键词： ternary forecast of heavy snow MOS multi-grade logistic regression neural networks threshold

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

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

Copper nanowire/multi-walled carbon nanotube com- posites as all-nanowire flexible electrode for fast-charging/ discharging lithium-ion battery

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Nano Research 2018年第2期11卷 769-779页

作者： Zhenxing Yin Sanghun Cho Duck-Jae You Yong-keon Ahn Jeeyoung Yoo Youn Sang Kim Program in Nano Science and Technology Graduate School of Convergence Science and Technology Seoul National University Seoul Republic of Korea Advanced Institutes of Convergence Technology Gyeonggi-do Republic of Korea

A novel lightweight three-dimensional （3D） composite anode for a fast-charging] discharging Li-ion battery （LIB） was fabricated entirely using one-dimensional （1D） nanomaterials, i.e., Cu nanowires （CuNWs） and multi-walled C nanotubes （MWCNTs）. Because of the excellent electrical conductivity, high-aspect ratio structures, and large surface areas of these nanomaterials, the CuNW-MWCNT composite （CNMC） with 3D structure provides significant advantages regarding the transport pathways for both electrons and ions. As an advanced binder-free anode, a CuNW-MWCNT composite film with a controllable thickness （~ 600 prn） exhibited a considerably low sheet resistance, and internal cell resistance. Furthermore, the random CuNW network with 3D structure acting as a rigid framework not only prevented MWCNT shrinkage and expansion due to aggregation and swelling but also minimized the effect of the volume change during the charge/discharge process. Both a half cell and a full cell of LIBs with the CNMC anode exhibited high specific capacities and Coulombic efficiendes, even at a high current. More importantly, we for the first time overcame the limitation of MWCNTs as anode materials for fast-charging]discharging LIBs （both half cells and full cells） by employing CuNWs, and the resulting anode can be applied to flexible LIBs. This innovative anode structure can lead to the development of ultrafast chargeable LIBs for electric vehides.

关键词： three-dimensional (3D)composite,all-nanowire electrode,fast chargeable batter3 fuN-cell Li-ion batteries(L1Bs),flexible battery

Incremental age-related one-year MACCE after acute myocardial infarction in the drug-eluting stent era （from KAMIR-NIH registry）

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Journal of Geriatric Cardiology 2018年第9期15卷 574-584页

作者： Dae-Won Kim Sung-Ho Her Ha Wook Park Kiyuk Chang Wook Sung Chung Ki bae Seung Myung Ho Jeong Hyo-Soo Kim Hyeon Cheoi Gwon In Whan Seong Kyung Kuk Hwang Shung Chull Chae Kwon-bae Kim Young Jo Kim Kwang Soo Cha Seok Kyu Oh Jei keon Chae Ji-Hoon Jung Division of Cardiology Daejeon St. Mary's Hospital College of Medicine the Catholic University of Korea Seoul South Korea Division of Cardiology Seoul St. Mary's Hospital College of Medicine the Catholic University of Korea Seoul South Korea Chonnam National University Hospital Gwangju South Korea Seoul National University Hospital Seoul South Korea Sungkyunkwan Universtiy Samsung Medical Center Seoul South Korea Chungnam National University Hospital Daejeon South Korea Chungbuk National University Hospital Cheongju South Korea Kyungpook National University Hospital Daegu South Korea Keimyung University Dongsan Medical Center Daegu South Korea Yeungnam University Hospital Daegu South Korea Pusan National University Hospital Busan South Korea Wonkwang University Hospital Iksan South Korea Chonbuk National University Hospital Jeonju South Korea Statistical Manager Institute of Toxicology Daejeon South Korea

Objectives To evaluate the age-related one-year major adverse cardiocerebrovascular events （MACCE） after percutaneous coronary intervention （PCI） in acute myocardial infarction （AMI）. We analyzed the association between age and one-year MACCE after AMI. Methods A total of 13,104 AMI patients from Korea Acute Myocardial Infarction Registry-National Institue of Health （KAMIR-NIH） between November 2011 and December 2015 were classified into four groups according to age （Group I, 〈 60 years, n = 4199; Group II, 60-70 years, n = 2577; Group III; 70-80 years, n = 2774; Group IV, ≥ 80 years, n = 1018）. Patients were analyzed for one-year composite of MACCE （cardiac death, myocardial infarction, target vessel revascularization, cerebrovascular events） after AMI. Results The one-year MACCE in AMI were 3.5% （Group I）, 6.3% （Group II）, 9.6% （Group III） and 17.6% （Group IV）. After adjustment for confounding para- meters, the analysis results showed that patients with AMI had incremental risk of one-year MACCE [Group II, adjusted hazard ratios （aHR） = 1.224, 95% CI： 0.965-1.525, P = 0.096; Group III, aHR = 1.316, 95% CI： 1.037-1.671, P= 0.024; Group IV, aHR = 1.975, 95% CI： 1.500-62.601, P〈 0.001） compared to Group I. Especially, cardiac death in the composite of primary end point played a major role in this effect （Group II, aHR = 1.335, 95% CI： 0.941-1.895, P= 0.106; Group III, aHR = 1.575, 95% CI： 1.122-2.210, P= 0.009; Group IV, aHR = 2.803, 95% CI： 1.937-4.054, P 〈 0.001）. Conclusions Despite advanced techniques and medications for PCI in AMI, age still exerts a powerful influence in clinical outcomes. Careful approaches, even in the modem era of developed cardiology are needed for aged-population in AMI intervention.

关键词： Acute myocardial infarction Aged-population Major adverse cardiocerebrovascular events

Significantly Improved High-Temperature Energy Storage Performance of BOPP Films by Coating Nanoscale Inorganic Layer

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Energy & Environmental Materials 2024年第2期7卷 30-38页

作者： Tiandong Zhang Hainan Yu Young Hoon Jung Changhai Zhang Yu Feng Qingguo Chen keon Jae Lee Qingguo Chi School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 350701Korea

Biaxially oriented polypropylene(BOPP)is one of the most commonly used commercial capacitor films,but its upper operating temperature is below 105℃due to the sharply increased electrical conduction loss at high *** this study,growing an inorganic nanoscale coating layer onto the BOPP film's surface is proposed to suppress electrical conduction loss at high temperature,as well as increase its upper operating *** kinds of inorganic coating layers that have different energy band structure and dielectric property are grown onto the both surface of BOPP films,*** effect of inorganic coating layer on the high-temperature energy storage performance has been systematically *** favorable coating layer materials and appropriate thickness enable the BOPP films to have a significant improvement in high-temperature energy storage ***,when the aluminum nitride(AIN)acts as a coating layer,the AIN-BOPP-AIN sandwich-structured films possess a discharged energy density of 1.5 J cm^(-3)with an efficiency of 90%at 125℃,accompanying an outstandingly cyclic *** the discharged energy density and operation temperature are significantly enhanced,indicating that this efficient and facile method provides an important reference to improve the high-temperature energy storage performance of polymer-based dielectric films.

关键词： coating layer energy storage interfacial barrier polymer films

Kinetic Study of Sulfur Dioxide Elimination by Limestone through the Lab Scale Circulating Fluidized Bed Combustor

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Advances in Materials Physics and Chemistry 2012年第4期2卷 189-192页

作者： Dowon Shun Dal-Hee bae In-Kyu Jang keon-Hee Park Seung Kyu Park Department of Chemical Engineering Hoseo University Asan 336-795 Korea Greenhouse Gas Research Center Korea Institute of Energy Research 71-2 Daejon 305-343 Korea Greenhouse Gas Research Center Korea Institute of Energy Research 71-2 Daejon 305-343 Korea

Characteristics of sulfur dioxide emission from coal and petroleum coke combustion were examined in a lab scale circulating fluidized bed (CFB) combustor. The rate constant of the first order rate expression for the absorption SO2 on the CaO surface was similar regardless of the origin of the limestone, the particle size and the initial SO2 concentration. However, the total SO2 absorption capacity was different depending on the origin of the limestone. The breakability of the particle which provides new surface for the reaction seems to play a major role in the absorption characteristics.

关键词： Sulfur Dioxide (SOx) Limestone Circulating Fluidized Bed Combustor Emission Kinetics First order reaction

Risk of ischaemic stroke in patients with transient global amnesia: a propensity-matched cohort study

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Stroke & Vascular Neurology 2022年第2期7卷 101-107页

作者： Sang Hun Lee keon-Yeup Kim Jeong-Woo Lee So-Jeong Park Jin-Man Jung Department of Neurology Korea University Ansan HospitalKorea University College of MedicineAnsanRepublic of Korea Data Science Team Hanmi Pharm.Co.LtdSeoulRepublic of Korea Korea University Zebrafish Translational Medical Research Center AnsanRepublic of Korea

Background The exact pathophysiological mechanism of transient global amnesia(TGA)is *** is debatable whether TGA is a risk factor for ***,here we investigated the possibility of TGA as a risk factor for stroke in a real-world setting using large-scale nationwide health claims *** We used health claims data from the Korean National Health Insurance Service(NHIS).Patients diagnosed with TGA between 2007 and 2013 were *** initially extracted patients without TGA who were preferentially matched for age and sex with the patients with TGA at a ratio of 10:1 from the whole ***,we performed 1:2 propensity score matching analysis to balance the baseline characteristics between the two *** the propensity score-matched dataset,we performed multivariable Cox regression analysis to investigate the association between TGA and stroke type,including ischaemic,haemorrhagic and all stroke *** Patients with TGA(n=14673)were selected from the NHIS *** extracting from the whole database(n=140486)and propensity score matching their data at a 1:2 ratio,a total of 10448 and 20442 patients were finally assigned to the TGA and control groups,*** multivariable Cox regression analysis demonstrated that the TGA group had a higher risk of ischaemic stroke and all types of stroke(adjusted HR=1.194;95%CI:1.043 to 1.368;and HR=1.197;95%CI:1.056 to 1.357,respectively).Conclusions Analysis of the nationwide claims database showed that TGA could be an important risk factor for stroke,especially for ischaemic stroke.

关键词： patients matched transient

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