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Transactions of Nonferrous Metals Society of China 2024年

作者： Yeongjung Kim Yong-Sung Eom kwang-seong choi Jong-Hyun Lee Department of Materials Science and Engineering Seoul National University of Science and Technology 232 Gongneung-ro Low-Carbon Integration Tech Creative Research Section ETRI 218 Gajeong-ro Materials Research Institute for Future Convergence Seoul National University of Science and Technology 232 Gongneung-ro

Four types of submicron Ag-coated Cu particles with different Ag contents were prepared as sintering paste fillers， and the Ag contents of the particles were measured to be 10， 20， 30， and 40 wt%. Four types of particles （in order of increasing Ag content: A10， A20， A30， and A40） were surface-modified with stearic acid， to suppress the Ag shell dewetting and improve sinterability. The surface-modified particles were mixed with a polyol-based solvent to fabricate a resin-free paste. Subsequently， the pastes were screen-printed onto a slide glass and sintered at 250 ℃ in a nitrogen atmosphere for 1–10 min to form an electrode. The electrical resistivity of the sintered film as a function of sintering time was measured using a four-point probe. All the four surface-modified Cu@Ag particles with different Ag contents exhibited decreased electrical resistivity. Particularly， the largest difference in values after and before the surface modification was observed for A40 with the highest Ag content; the electrical resistivities of the initial and surface-modified particles were 1.51×10-4and 6.67×10-5Ω·cm， respectively， after sintering for 10 min. The findings of this study confirmed that the surface modification using stearic acid effectively suppressed the dewetting of the Ag shell and improved the sinterability of the submicron Cu@Ag particles.

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Correlation between hydration properties and electrochemical performances on Ln cation size effect in layered perovskite for protonic ceramic fuel cells

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Journal of Energy Chemistry 2024年第1期88卷 1-9,I0001页

作者： Inhyeok Cho Jiwon Yun Boseok seong Junseok Kim Sun Hee choi Ho-Il Ji Sihyuk choi Department of Mechanical Engineering Kumoh National Institute of TechnologyGumi 39177GyeongbukRepublic of Korea Department of Aeronautics Mechanical and Electronic Convergence EngineeringKumoh National Institute of TechnologyGumi 39177GyeongbukRepublic of Korea Center for Energy Materials Research Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Center for Hydrogen and Fuel Cell Research Clean Technology Research DivisionKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Department of Energy and Environmental Engineering University of Science and TechnologySeoul 02792Republic of Korea Nanomaterials Science and Engineering Korea University of Science and Technology(UST)KIST CampusSeoul 02792Republic of Korea

PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF < Nd BSCF < Gd BSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.

关键词： Protonic ceramic fuel cell Cathode Triple ionic and electronic conductor Hydration property Proton uptake Gibbs free energy

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Effect of pre-twinning and heat treatment on formability of AZX311 Mg alloy

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Journal of Magnesium and Alloys 2024年第3期12卷 1154-1169页

作者： Mahesh Panchal Lalit Kaushik Min-seong Kim Ravi Kottan Renganayagalu Shi-Hoon choi Jaiveer Singh Department of Mechanical Engineering Indian Institute of Technology JodhpurKarwarJodhpur 342030RajasthanIndia Department of Metallurgical and Materials Engineering Indian Institute of Technology JodhpurKarwarJodhpur 342030RajasthanIndia Energy Materials Research Center Korea Institute of Science and Technology(KIST)5 Hwarang-roSeongbuk-guSeoul 02792Republic of Korea Department of Advanced Components and Materials Engineering Sunchon National University255 Jungang-roSuncheonJeonnam 57922Republic of Korea

In this study,the effects of pre-strain-induced tensile twins(TTWs)and controlled heat treatment on the formability behavior of AZX311 Mg alloy sheets were investigated.A 4%compressive strain was applied to pre-strain the sheets using the in-plane compression(IPC)technique along the rolling direction(RD)to introduce *** pre-strained(PS)samples were subsequently heat-treated at 250℃,350℃,and 400℃ independently for 1 hr,and are termed as PSA1,PSA2,and PSA3,*** cupping tests were conducted to assess the formability of the sheet samples under different initial *** results showed that the PS sample heat-treated at 250℃ for 1hr exhibited a decrease in the Erichsen index(IE)compared to the as-rolled sample,whereas PSA2 and PSA3 samples showed an increase in IE *** analysis revealed that most of the TTWs generated through pre-twinning were stable at 250℃;however,the twin volume fraction reduced to 41%at 350℃ compared to the PS samples due to enhanced thermal activity at that ***,PSA2 samples showed severe grain coarsening in some areas of the sample,and the fraction of such grains increased in the PSA3 *** stretch formability(IE value)of PSA2 samples showed a 32.3%increase compared to the as-rolled ***,the analysis of the deformed specimen at failure under the Erichsen test indicated that considerable detwinning occurs in the PS and PSA1 samples,whereas dislocation slip activity dominates in the PSA2 and PSA3 samples during stretch *** from detwinning and dislocation slip,deformation twins were also observed in all samples after the Erichsen ***,this work highlights the importance of texture control and its underlying mechanisms via pre-twinning followed by heat treatment and their impact on the room temperature(RT)stretch formability of AZX311 Mg alloy sheets.

关键词： Mg alloys Pre-twinning Texture Formability EBSD.

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Prevalence of nonalcoholic fatty liver disease in pediatrics and adolescents:a systematic review and meta-analysis

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World Journal of Pediatrics 2024年第6期20卷 569-580页

作者： Eun Joo Lee Miyoung choi Sang Bong Ahn Jeong-Ju Yoo seong Hee Kang Yuri Cho Do Seon Song Hong Koh Dae Won Jeon Hye Won Lee Department of Pediatrics Yonsei University College of MedicineSeoulKorea Clinical Evidence Research National Evidence-Based Healthcare Collaborating Agency(NECA)SeoulKorea Department of Internal Medicine Nowon Eulji Medical CenterEulji University College of MedicineSeoulKorea Department of Internal Medicine Soonchunhyang University Bucheon HospitalBucheonKorea Department of Internal Medicine Sangkye Paek HospitalInje University College of MedicineSeoulKorea Center for Liver and Pancreatobiliary Cancer National Cancer CenterGoyangKorea Department of Internal Medicine College of MedicineSt.Vincent's HospitalThe Catholic University of KoreaSuwonKorea Department of Internal Medicine Hanyang University College of MedicineSeoulKorea Department of Internal Medicine Yonsei University College of MedicineSeoulKorea

Background As childhood obesity escalates worldwide,the prevalence of nonalcoholic fatty liver disease(NAFLD)in pediatric and adolescent populations is also ***,systematic studies and meta-analyses evaluating the prevalence of pediatric NAFLD remain *** The MEDLINE,Korean Medical Database(KMBASE),Embase,Global Health,and Cochrane Library databases were searched from January 1997 to April *** terms included NAFLD or steatosis;nonalcoholic or steatohepatitis;child(ren),adolescent,or teenager;and prevalence,incidence,or epidemiology.A random-effects meta-analysis model was used to estimate the prevalence of pediatric *** A total of 2116 publications were found,of which 62 were included in the *** them,27 reported the prevalence in the general population and 39 in the obese *** worldwide pooled prevalence of pediatric NAFLD was 13%[95%confidence interval(CI)9-18%]in the general population and 47%(95%CI 41%–53%)in the obese *** 16 studies in the general population and 18 in the obese population,NAFLD prevalence varied by *** the general population,the prevalence of NAFLD was 15%(95%CI 8%–23%)in males and 10%(95%CI 6%–15%)in *** the obese population,it was 54%(95%CI 46%–61%)in males and 39%(95%CI 30%–49%)in *** The global prevalence of pediatric NAFLD is rising in both the general and obese *** the increasing rates of childhood obesity,epidemiological studies on the prevalence and incidence of NAFLD are needed.

关键词： Meta-analysis Nonalcoholic fatty liver disease Pediatric Prevalence

Controlled afterglow luminescent particles for photochemical tissue bonding

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Light(Science & Applications) 2022年第11期11卷 2755-2765页

作者： seong-Jong Kim Minji choi Guosong Hong Sei kwang Hahn Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohangGyeongbuk 37673Korea Department of Materials Science and Engineering Stanford UniversityStanfordCA 94305USA

Upconversion materials(UCMs)have been developed to convert tissue-penetrating near-infrared(NIR)light into visible ***,the low energy conversion effciency of UCMs has limited their further biophotonic ***,we developed controlled afterglow luminescent particles(ALPs)of ZnS:Ag,Co with strong and persistent green luminescence for photochemical tissue bonding(PTB).The co-doping of Ag^(+) and Co^(2+) ions into ZnS:Ag,Co particles with the proper vacancy formation of host ions resulted in high luminescence intensity and long-term *** addition,the ALPs of ZnS:Ag,Co could be recharged rapidly under short ultraviolet(UV)irradiation,which effectively activated rose bengal(RB)in hyaluronate-RB(HA-RB)conjugates for the crosslinking of dissected collagen layers without additional light *** remarkable PTB of ZnS:Ag,Co particles with HA-RB conjugates was confirmed by in vitro collagen fibrillogenesis assay,in vivo animal wound closure rate analysis,and in vivo tensile strength evaluation of incised skin *** together,we could confirm the feasibility of controlled ALPs for various biophotonic applications.

关键词： bonding fir closure

Finite element analysis using elasto-visco-plastic self-consistent polycrystal model for E-form Mg sheet subjected to bending

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Journal of Magnesium and Alloys 2023年第4期11卷 1393-1407页

作者： Bohye Jeon Min-seong Kim Shi-Hoon choi Youngung Jeong Department of Materials Convergence and System Engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea Center for Energy Materials Research Korea Institute of Science and TechnologySeoulRepublic of Korea Department of Advanced Components and Materials Engineering Sunchon National UniversitySuncheon-siJeollanam-doRepublic of Korea School of Materials Science and Engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea

The mechanical behavior of a magnesium alloy E-form under bending was investigated using the elasto-visco-plastic polycrystal model(ΔEVPSC) and its finite element(FE) implementation(ΔEVPSC-FE) developed in Jeong et al. and Jeong and Tomé. The crystallographic orientation distribution(COD) obtained from X-ray diffraction was used to represent the initial texture, and the Voce hardening parameters were calibrated by fitting the uniaxial tension and the compression flow stress curves. A quasi-static FE analysis of a miniaturized V-bending operation was conducted using the ΔEVPSC-FE model. The bending induced an inhomogeneous stress response along the through-thickness and the lateral directions, which was well captured by the model. Moreover, the predictive capability of the model was validated by comparing with various experimental results such as(1) force vs. displacement curves;(2) the through-thickness variations in the twin volume fraction;and(3) the changes in crystallographic texture as a function of displacement. Additional bending simulation was performed using an isotropic texture, the result of which suggests that the potential improvement in bendability of the magnesium alloy is attainable by weakening the initial texture. Moreover, the simulation results imply that the crystallographic texture, which may affect the twin activation across the thickness direction, plays a significant role in the shifting direction of the neutral layer.

关键词： FEM Texture V-bending Polycrystal Magnesium Elasto-visco-plasticity

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Experience of limited pancreatic head resection for management of branch duct intraductal papillary mucinous neoplasm in a single center

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World Journal of Gastroenterology 2009年第23期15卷 2904-2907页

作者： kwang Yeol Paik seong Ho choi Department of Surgery Kepco Medical Foundation Hanil General Hospital #388-1 Ssangmoon-Dong Dobong-Gu Seoul 132-033 South Korea Department of Surgery Samsung Medical Center College of Medicine Sungkyunkwan University #50 Irwon-Dong Gangnam-Gu Seoul 135-710 South Korea

AIM: To share our surgical experience and the outcome of limited pancreatic head resection for the management of branch duct intraductal papillary mucinous neoplasm (IPMN). METHODS: Between May 2005 and February 2008, nine limited pancreatic head resections (LPHR) were performed for IPMN of the pancreatic head. We reviewed the nine patients, retrospectively. RESULTS: Tumor was located in the uncinate process of the pancreas in all nine patients. Three patients had stents inserted in the main pancreatic duct due to injury. The mean size of tumor was 28.4 mm. Postoperative complications were found in f ive patients: 3 pancreatic leakages, a pancreatitis, and a duodenal stricture. Pancreatic leakages were improved by external drainage. No perioperative mortality was observed and all patients are recorded alive during the mean follow-up period of 17.2 mo. CONCLUSION: In selected patients after careful evaluation, LPHR can be used for the treatment of branch duct type IPMN. In order to avoid pancreatic ductal injury, preand intra-operative defi nite localization and careful operative techniques are required.

关键词：黏液性肿瘤乳头管内管理围手术期胰腺炎十二指肠

Sulfur-doped hard carbon hybrid anodes with dual lithium-ion/metal storage bifunctionality for high-energy-density lithium-ion batteries

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Carbon Energy 2023年第1期5卷 71-81页

作者： Sungmin Cho Jong Chan Hyun Son Ha Yeonhua choi Honggyu seong Jaewon choi Hyoung-Joon Jin Young Soo Yun Program in Environmental and Polymer Engineering Inha UniversityIncheonSouth Korea KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoulSouth Korea Departmant of Chemistry and Research Institute of Natural Science Gyeongsang National UniversityJinjuSouth Korea Department of Polymer Science and Engineering Inha UniversityIncheonSouth Korea Division of Energy Engineering Kangwon National UniversityGangwon-doSouth Korea

Bifunctional hybrid anodes(BHAs),which are both a high-performance active host material for lithium-ion storage as well as a guiding agent for homogeneous lithium metal nucleation and growth,exhibit significant potential as anodes for next-generation high-energy-density lithium-ion batteries(LIBs).In this study,sulfur-doped hard carbon nanosphere assemblies(S-HCNAs)were prepared through a hydrothermal treatment of a liquid organic precursor,followed by high-temperature thermal annealing with elemental sulfur for application as BHAs for *** a carbonate-based electrolyte containing fluoroethylene carbonate additive,the S-HCNAs showed high lithium-ion storage capacities in sloping as well as plateau voltage sections,good rate capabilities,and stable *** addition,high average Coulombic efficiencies(CEs)of~96.9%were achieved for dual lithium-ion and lithium metal storage *** the LIB full-cell tests with typical NCM811 cathodes,the S-HCNA-based BHAs containing~400 mA h g^(−1) of excess lithium led to high energy and power densities of~500Wh kg^(−1) and~1695Wkg^(−1),respectively,and a stable cycling performance with~100%CEs was achieved.

关键词： hard carbon hybrid anode lithium-ion batteries lithium metal anode lithium metal batteries sulfur-doped carbon

Integrating Deep Learning and Machine Translation for Understanding Unrefined Languages

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Computers, Materials & Continua 2022年第1期70卷 669-678页

作者： Hong Geun Ji Soyoung Oh Jina Kim seong choi Eunil Park Department of Applied Artificial Intelligence Sungkyunkwan UniversitySeoul03063Korea Raon Data Seoul03073Korea Department of Computer Science and Engineering University of MinnesotaMinneapolis55455MNUSA

In the field of natural language processing(NLP),the advancement of neural machine translation has paved the way for cross-lingual ***,most studies in NLP have evaluated the proposed language models on well-refined *** investigatewhether amachine translation approach is suitable for multilingual analysis of unrefined datasets,particularly,chat messages in *** order to address it,we collected the dataset,which included 7,066,854 and 3,365,569 chat messages from English and Korean streams,*** employed several machine learning classifiers and neural networks with two different types of embedding:word-sequence embedding and the final layer of a pre-trained language *** results of the employed models indicate that the accuracy difference between English,and English to Korean was relatively high,ranging from 3%to 12%.For Korean data(Korean,and Korean to English),it ranged from 0%to 2%.Therefore,the results imply that translation from a low-resource language(e.g.,Korean)into a high-resource language(e.g.,English)shows higher performance,in contrast to vice *** implications and limitations of the presented results are also *** instance,we suggest the feasibility of translation from resource-poor languages for using the tools of resource-rich languages in further analysis.

关键词： Twitch multilingual machine translation machine learning

Diagnosis of Middle Ear Diseases Based on Convolutional Neural Network

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Computer Systems Science & Engineering 2023年第8期46卷 1521-1532页

作者： Yunyoung Nam seong Jun choi Jihwan Shin Jinseok Lee Department of Computer Science and Engineering Soonchunhyang UniversityAsan31538Korea Department of Otolaryngology-Head and Nech Surgery Soonchunhyang University College of MedicineCheonan HospitalCheonan31151Korea Department of Biomedical Engineering Kyung Hee UniversityYonginKorea

An otoscope is traditionally used to examine the eardrum and ear canal.A diagnosis of otitis media(OM)relies on the experience of *** an examiner lacks experience,the examination may be difficult and *** paper presents an ear disease classification method using middle ear images based on a convolutional neural network(CNN).Especially the segmentation and classification networks are used to classify an otoscopic image into six classes:normal,acute otitis media(AOM),otitis media with effusion(OME),chronic otitis media(COM),congenital cholesteatoma(CC)and traumatic perforations(TMPs).The Mask R-CNN is utilized for the segmentation network to extract the region of interest(ROI)from otoscopic *** extracted ROIs are used as guiding features for the *** classification is based on transfer learning with an ensemble of two CNN classifiers:EfficientNetB0 and *** proposed model was trained with a 5-fold cross-validation *** proposed method was evaluated and achieved a classification accuracy of 97.29%.

关键词： Otitis media convolutional neural network acute otitis media otitis media with effusion chronic otitis media congenital cholesteatoma traumatic perforation Mask R-CNN