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Rare Metals 2020年第8期39卷 918-927页

作者： Si-Jun Park kyu-hyuk lee Seong-Moon Seo Hi-Won Jeong Young-Soo Yoo HeeJin Jang Multi-Material Research Center Gwangju-Jeonnam DivisionKorea Automotive Technology InstituteGwangju 62207Republic of Korea Department of Advanced Materials Engineering Chosun UniversityGwangju 61452Republic of Korea High Temperature Materials Group Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Chosun UniversityGwangju 61452Republic of Korea

The effects of alloying elements(Co,Cr,Mo,W,Al,Ti,and Ta)on the oxidation resistance of Ni-(0-15)Co-(8-15)Cr-(0-5)Mo-(0-10)W-(3-8)Al-(0-5)Ti-(0-10)Ta-0.1 C-0.01 B alloys were *** sample compositions were designed by the Box-Behnken method of design of experiments(DOE).The alloying elements show complicated effects on the mass gain due to oxidation,depending on the alloy *** reduces the mass gain *** other elements except Al do not appear to exert a strong effect on the oxidation rate on average,but their influences are shown clearly in the alloys with a low Al ***,W,and Ta reduce the oxidation rate,while Cr,Mo,and Ti promote *** is the most effective element in reducing the oxidation rate of the alloy with a low Al *** is confirmed that a continuous Al2O3 layer is essentially required for high oxidation *** oxide scale of easily oxidized alloys has various oxides such as NiCr2O4,NiAl2O4,NiO,Cr2O3,CrTaO4,and TiO2.

关键词： High temperature oxidation Alloy composition Ni-based superalloy Oxidation resistance Design of experiments

A Simple Embedding Method for the Laplace-Beltrami Eigenvalue Problem onImplicit Surfaces

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1189-1216页

作者： Young kyu lee Shingyu Leung Department of Mathematics The Hong Kong University of Science and TechnologyClear Water BayHong KongChina

We propose a simple embedding method for computing the eigenvalues and eigenfunctions of the Laplace-Beltrami operator on implicit *** approach follows an embedding approach for solving the surface eikonal *** replace the differential operator on the interface with a typical Cartesian differential operator in the surface *** proposed algorithm is easy to implement and *** will give some two-and three-dimensional numerical examples to demonstrate the effectiveness of our proposed approach.

关键词： Laplace-Beltrami operator Level set method Implicit representation Eigenvalues Numerical PDEs

Enhanced prediction of anisotropic deformation behavior using machine learning with data augmentation

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Journal of Magnesium and Alloys 2024年第1期12卷 186-196页

作者： Sujeong Byun Jinyeong Yu Seho Cheon Seong Ho lee Sung hyuk Park Taekyung lee School of Mechanical Engineering Pusan National UniversityBusan 46241South Korea School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566South Korea

Mg alloys possess an inherent plastic anisotropy owing to the selective activation of deformation mechanisms depending on the loading *** characteristic results in a diverse range of flow curves that vary with a deformation *** study proposes a novel approach for accurately predicting an anisotropic deformation behavior of wrought Mg alloys using machine learning(ML)with data *** developed model combines four key strategies from data science:learning the entire flow curves,generative adversarial networks(GAN),algorithm-driven hyperparameter tuning,and gated recurrent unit(GRU)*** proposed model,namely GAN-aided GRU,was extensively evaluated for various predictive scenarios,such as interpolation,extrapolation,and a limited dataset *** model exhibited significant predictability and improved generalizability for estimating the anisotropic compressive behavior of ZK60 Mg alloys under 11 annealing conditions and for three loading *** GAN-aided GRU results were superior to those of previous ML models and constitutive *** superior performance was attributed to hyperparameter optimization,GAN-based data augmentation,and the inherent predictivity of the GRU for *** a first attempt to employ ML techniques other than artificial neural networks,this study proposes a novel perspective on predicting the anisotropic deformation behaviors of wrought Mg alloys.

关键词： Plastic anisotropy Compression Annealing Machine learning Data augmentation

Effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on tensile and bending properties of high-Al-containing Mg alloys

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Journal of Magnesium and Alloys 2024年第2期12卷 779-793页

作者： Sumi Jo Gyo Myeong lee Jong Un lee Young Min Kim Sung hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Magnesium Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on the uniaxial tensile and three-point bending properties of extruded Mg alloys containing high Al *** extruded Mg–9Al–1Zn–0.3Mn(AZ91)alloy contains lamellar-structured Mg_(17)Al_(12)discontinuous precipitates along the grain boundaries,which are formed via static precipitation during natural air *** extruded Mg–11Al–1Zn–0.3Mn(AZ111)alloy contains spherical Mg_(17)Al_(12)precipitates at the grain boundaries and inside the grains,which are formed via dynamic precipitation during *** to inhomogeneous distribution of precipitates,the AZ111 alloy consists of two different precipitate regions:precipitate-rich region with numerous precipitates and finer grains and precipitate-scarce region with a few precipitates and coarser *** AZ111 alloy exhibits a higher tensile strength than the AZ91 alloy because its smaller grain size and more abundant precipitates result in stronger grain-boundary hardening and precipitation hardening effects,***,the tensile elongation of the AZ111 alloy is lower than that of the AZ91 alloy because the weak cohesion between the dynamic precipitates and the matrix facilitates the crack initiation and *** bending,a macrocrack initiates on the outer surface of bending specimen in both *** AZ111 alloy exhibits higher bending yield strength and lower failure bending strain than the AZ91 *** bending specimens of the AZ91 alloy have similar bending formability,whereas those of the AZ111 alloy exhibit considerable differences in bending formability and crack propagation behavior,depending on the distribution and number density of precipitates in the *** bending specimens of the AZ111 alloy,it is found that the failure bending strain(ε_(f,bending))is inversely proportional to the area fraction of precipitates in the outer zone of bending specimen(A_(ppt)),with a relation

关键词： Mg–Al alloy Extrusion Bending Precipitation Microstructure

Acetylacetone-TiO_(2) Promoted Large Area Compatible Cascade Electron Transport Bilayer for Efficient Perovskite Solar Cells

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Energy & Environmental Materials 2024年第2期7卷 221-228页

作者： Hyong Joon lee Jin Kyoung Park Jin Hyuck Heo Sang hyuk Im Department of Chemical and Biological Engineering Korea University145 Anam-ro Seongbuk-guSeoul 17104Korea

In designing efficient perovskite solar cells(PSCs),the selection of suitable electron transport layers(ETLs)is critical to the final device performance as they determine the driving force for selective charge ***_(2)nanoparticles(NPs)based ETLs have been a popular choice for PSCs due to superior electron mobility,but their relatively deep-lying conduction band energy levels(ECB)result in substantial potential ***,TiO_(2)NPs establish favorable band alignment owing to shallower ECB,but their low intrinsic mobility and abundant surface trap sites impede the final *** this reason,constructing a cascaded bilayer ETL is highly desirable for efficient PSCs,as it can rearrange energy levels and exploit on advantages of an individual *** this study,we prepare SnO_(2)NPs and acetylacetone-modified TiO_(2)(Acac-TiO_(2))NPs and implement them as bilayer SnO_(2)/Acac-TiO_(2)(BST)ETL,to assemble cascaded energy band ***_(2)contributes to rapid charge carrier transport from high electron mobility while Acac-TiO_(2)minimizes band-offset and effectively suppresses interfacial ***,the optimized BST ETL generates synergistic influence and delivers power conversion efficiency(PCE)as high as 23.14%with open-circuit voltage(V_(oc))reaching 1.14 ***,the BST ETL is transferred to a large scale and the corresponding mini module demonstrates peak performance of 18.39%PCE from 25 cm^(2)aperture ***,the BST-based mini module exhibit excellent stability,maintaining 83.1%of its initial efficiency after 1000 h under simultaneous 1 Sun light-soaking and damp heat(85℃/RH 85%)environment.

关键词： acetylacetone large area perovskite solar cells TiO_(2)

Intelligent reflecting surface for sum rate enhancement in MIMO systems

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Digital Communications and Networks 2024年第1期10卷 94-100页

作者： Chan-Yeob Park Ji-Sung Jung Yeong-Rong lee Beom-Sik Shin Hyoung-kyu Song Department of Information and Communication Engineering Sejong UniversitySeoulGwangjin-guGunja-dong 98Republic of Korea Department of Convergence Engineering for Intelligent Drone Sejong University SeoulGwangjin-guGunja-dong 98Republic of Korea

The research for the Intelligent Reflecting Surface(IRS)which has the advantages of cost and energy efficiency has been *** capacity can be effectively increased by appropriately setting the phase value of IRS elements according to the channel ***,the problem of obtaining an appropriate phase value of IRs is difficult to solve due to the non-convex *** paper proposes an iterative algorithm for the alternating optimal solution in the Single User Multiple-Input-Multiple-Output(SU-MIMO)*** proposed iterative algorithm finds an alternating optimal solution that is the phase value of IRS one by *** results show that the proposed method has better performance than that of the randomized IRS *** number of iterations for maximizing the performance of the proposed algorithm depends on the channel state between the IRS and the receiver.

关键词： Intelligent reflecting surface MIMO Sum rate

Mixed-dimensional stacked nanocomposite structures for a specific wavelength-selectable ambipolar photoresponse

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Nano Research 2024年第6期17卷 5549-5558页

作者： Young Jae Park Jaeho Shim Joo Song lee kyu Seung lee Ji-Yeon Kim Kang Bok Ko Sang-Youp Yim Seongjun Kim Hoon-kyu Shin Donghee Park Yong Ju Yun Dong Ick Son Institute of Advanced Composite Materials Korea Institute of Science and TechnologyJeollabuk-do 55324Republic of Korea National Institute for Nanomaterials Technology Pohang University of Science and TechnologyGyeongsangbuk-do 37673Republic of Korea Department of Semiconductor Science and Technology Semiconductor Physics Research CenterJeonbuk National UniversityJeonju 54896Republic of Korea Advanced Photonics Research Institute Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Center for Opto-Electronic Materials and Devices Post-Silicon Semiconductor InstituteKorea Institute of Science and TechnologySeoul 02792Republic of Korea Graduate School of Energy and Environment(KU-KIST Green School) Korea UniversitySeoul 02841Republic of Korea KIST School Department of Nanomaterials and Nano ScienceUniversity of Science and Technology(UST)Daejeon 34113Republic of Korea

Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to the potential to generate new optical ***,we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide(WSe_(2))/CdSeS QDs monolayer/molybdenum disulfide(MoS_(2))(2D/0D/2D).Specifically,it exhibits an ambipolar photoresponse characteristic,with a negative photoresponse observed in the 400-600 nm wavelength range and a positive photoresponse appeared at 700 nm *** resulted in the high negative responsivity of up to 52.22 mA·W^(−1)under 400 nm,which is 163 times higher than that of the photodetector without CdSeS *** also demonstrated the negative photoresponse,which could be due to increased carrier collision probability and non-radiative *** modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent ***,we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum *** study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications.

关键词： mixed-dimension quantum dot heterostructure photodetector ambipolar photoresponse

Depolarization mitigated in ferroelectric Hf_(0.5)Zr_(0.5)O_(2)ultrathin films(<5 nm)on Si substrate by interface engineering

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Journal of Advanced Ceramics 2024年第3期13卷 282-292页

作者： Se Hyun Kim Younghwan lee Dong Hyun lee Geun Hyeong Park Hyun Woo Jeong Kun Yang Yong Hyeon Cho Young Yong Kim Min hyuk Park Department of Materials Science and Engineering College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Research Institute of Advanced Materials College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Inter-university Semiconductor Research Center College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Pohang Accelerator Laboratory Pohang University of Science&TechnologyPohang 790784Republic of Korea

(Hf,Zr)O_(2)offers considerable potential for next-generation semiconductor devices owing to its nonvolatile spontaneous polarization at the ***,scaling this material to sub-5 nm thickness poses several challenges,including the formation of an interfacial layer and high trap *** particular,a low-k SiO_(2)interfacial layer is naturally formed when(Hf,Zr)O_(2)films are directly grown on a Si substrate,leading to high depolarization fields and rapid reduction of the remanent *** address these issues,we conducted a study to significantly improve ferroelectricity and switching endurance of(Hf,Zr)O_(2)films with sub-5 nm thicknesses by inserting a TiO_(2)interfacial *** deposition of a Ti film prior to Hf_(0.5)Zr_(0.5)O_(2)film deposition resulted in a high-k TiO_(2)interfacial layer and prevented the direct contact of Hf_(0.5)Zr_(0.5)O_(2)with *** findings show that the high-k TiO_(2)interfacial layer can reduce the SiO_(2)/Si interface trap density and the depolarization field,resulting in a switchable polarization of 60.2μC/cm^(2)for a 5 nm thick Hf_(0.5)Zr_(0.5)O_(2)***,we propose that inserting a high-k TiO_(2)interfacial layer between the Hf_(0.5)Zr_(0.5)O_(2)film and the Si substrate may offer a promising solution to enhancing the ferroelectricity and reliability of(Hf,Zr)O_(2)grown on the Si substrate and can pave the way for next-generation semiconductor devices with improved performance.

关键词： ferroelectric charge trapping hafnia depolarization

Global public concern of childhood and adolescence suicide:a new perspective and new strategies for suicide prevention in the post-pandemic era

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World Journal of Pediatrics 2024年第9期20卷 872-900页

作者： Soeun Kim Jaeyu Park Hyeri lee Hayeon lee Selin Woo Rosie Kwon Sunyoung Kim Ai Koyanagi lee Smith Masoud Rahmati Guillaume Fond Laurent Boyer Jiseung Kang Jun hyuk lee Jiyeon Oh Dong Keon Yon Center for Digital Health Medical Science Research InstituteKyung Hee University College of MedicineSeoulSouth Korea Department of Precision Medicine Kyung Hee University College of MedicineSeoulSouth Korea Department of Regulatory Science Kyung Hee UniversitySeoulSouth Korea Department of Family Medicine Kyung Hee University Medical CenterKyung Hee University College of MedicineSeoulSouth Korea Research and Development Unit Parc Sanitari Sant Joan de DeuBarcelonaSpain Centre for Health Performance and WellbeingAnglia Ruskin UniversityCambridgeUK Department of Physical Education and Sport Sciences Faculty of Literature and Human SciencesLorestan UniversityKhoramabadIran Department of Physical Education and Sport Sciences Faculty of Literature and HumanitiesVali-e-Asr University of RafsanjanRafsanjanIran CEReSS-Health Service Research and Quality of Life Center Assistance Publique-Hôpitaux de MarseilleAix Marseille UniversityMarseilleFrance Department of Anesthesia Critical Care and Pain MedicineMassachusetts General HospitalBostonMAUSA Division of Sleep Medicine Harvard Medical SchoolBostonMAUSA Health and Human Science University of Southern CaliforniaLos AngelesCAUSA Department of Medicine Kyung Hee University College of MedicineSeoulSouth Korea Department of Pediatrics Kyung Hee University Medical CenterKyung Hee University College of Medicine23 Kyungheedae-roDongdaemun-guSeoul02447South Korea

Background Suicide is the second leading cause of death in young people worldwide and is responsible for about 52,000 deaths annually in children and adolescents aged 5-19 ***,social,psychological,and behavioral factors play important roles in suicide *** traumatic events such as the COVID-19 pandemic may contribute to suicidal behaviors in young people,there is a need to understand the current status of suicide in adolescents,including its epidemiology,associated factors,the influence of the pandemic,and management *** sources We investigated global and regional suicide mortality rates among children and adolescents aged 5-19 years using data from the Global Burden of Diseases,Injuries,and Risk Factors Study(GBD)*** suicide mortality rates from 1990 to 2019 were examined in 204 countries and territories across six World Health Organization(WHO)***,we utilized electronic databases,including PubMed/MEDLINE and Scopus,and employed various combinations of terms such as“suicide”,“adolescents”,“youth”,“children”,“risk factors”,“COVID-19 pandemic”,“prevention”,and“intervention”to provide a narrative review on suicide within the pediatric population in the post-pandemic *** Despite the decreasing trend in the global suicide mortality rate from 1990 to 2019,it remains *** mortality rates from suicide by firearms or any other specified means were both greater in ***,Southeast Asia had the highest suicide rate among the six WHO *** COVID-19 pandemic seems to contribute to suicide risk in young people;thus,there is still a strong need to revisit appropriate management for suicidal children and adolescents during the *** The current narrative review integrates up-to-date knowledge on suicide epidemiology and the effects of the COVID-19 pandemic,risk factors,and intervention *** numerous studies have characterized trends in suicide among young people during the

关键词： COVID-19 Global Pandemic Suicide Children Adolescents

Highly efficient and stable organic solar cells with SnO_(2)electron transport layer enabled by UV-curing acrylate oligomers

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Journal of Energy Chemistry 2024年第5期92卷 124-131页

作者： Mwende Mbilo Du Hyeon Ryu Seungjin lee Muhammad Haris Julius Mwakondo Mwabora Robinson Juma Musembi Hang Ken lee Sang kyu lee Chang Eun Song Won Suk Shin Department of Physics Faculty of Science and TechnologyUniversity of Nairobi(UoN)P.O.Box 30197-00100NairobiKenya Advanced Energy Materials Research Center Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea Advanced Materials and Chemical Engineering University of Science and Technology(UST)Daejeon 34113Republic of Korea

The interfaces between the inorganic metal oxide and organic photoactive layer are of outmost importance for efficiency and stability in organic solar cells(OSCs).Tin oxide(SnO_(2))is one of the promising candidates for the electron transport layer(ETL)in high-performance inverted *** a solution-processed SnO_(2)ETL is employed,however,the presence of interfacial defects and suboptimal interfacial contact can lower the power conversion efficiency(PCE)and operational stability of ***,highly efficient and stable inverted OSCs by modification of the SnO_(2)surface with ultraviolet(UV)-curable acrylate oligomers(SAR and OCS)are *** highest PCEs of 16.6%and 17.0%are achieved in PM6:Y6-BO OSCs with the SAR and OCS,respectively,outperforming a device with a bare SnO_(2)ETL(PCE 13.8%).The remarkable enhancement of PCEs is attributed to the optimized interfacial contact,leading to mitigated surface *** strikingly,improved light-soaking and thermal stability strongly correlated with the interfacial defects are demonstrated for OSCs based on SnO_(2)/UV cross-linked resins compared to OSCs utilizing bare SnO_(2).We believe that UV cross-linking oligomers will play a key role as interfacial modifiers in the future fabrication of large-area and flexible OSCs with high efficiency and stability.

关键词： Organic solar cells SnO_(2) Surface defects Ultraviolet resins Stability Cross-linking oligomers Non-halogenated solvent