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Comparison of commercial silicon-based anode materials for the design of a high-energy lithium-ion battery

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Nano Research 2024年第6期17卷 5270-5277页

作者： Minhong choi Eunhan Lee Jaekyung sung Namhyung Kim Minseong Ko Division of Convergence Materials Engineering Pukyong National UniversityBusan 48547Republic of Korea Department of Materials Engineering and Convergence Technology Gyeongsang National University501 Jinju-daeroJinju 52828Republic of Korea Department of Materials System Engineering Pukyong National UniversityBusan 48547Republic of Korea

Silicon(Si)is considered a potential alternative anode for next-generation Li-ion batteries owing to its high theoretical capacity and ***,the commercial use of Si anodes is hindered by their large volume expansion(~300%).Numerous efforts have been made to address this *** these efforts,Si-graphite co-utilization has attracted attention as a reasonable alternative for high-energy anodes.A comparative study of representative commercial Si-based materials,such as Si nanoparticles,Si suboxides,and Si−Graphite composites(SiGC),was conducted to characterize their overall performance in high-energy lithium-ion battery(LIB)design by incorporating conventional ***-Si was found to exhibit poor electrochemical performance,with severe volume expansion during *** suboxide provided excellent cycling stability in a full-cell evaluation with stable volume variation after 50 cycles,but had a large irreversible capacity and remarkable volume expansion during the first *** displayed a good initial Coulombic efficiency and the lowest volume change in the first cycle owing to the uniformly distributed nano-Si layer on graphite;however,its long-term cycling stability was relatively *** complement each disadvantage of Si suboxide and SiGC,a new combination of these Si-based anodes was suggested and a reasonable improvement in overall battery performance was successfully achieved.

关键词： silicon-based anode high-energy comparison lithium ion battery blended electrode

Particle morphology control for spherical powder fabrication using the ball milling process with DEM simulation

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Particuology 2024年第7期90卷 41-50页

作者： Battsetseg Jargalsaikhan Khulan Uranchimeg Amgalan Bor Kyung sung Kim Heekyu choi Research Institute of Future Convergence Changwon National UniversityChangwonGyoungnam 641-773Republic of Korea Graduate School of Material Science Engineering Changwon National UniversityChangwonGyoungnam 641-773Republic of Korea Department of Chemical and Biological Engineering School of Engineering and Applied SciencesNational University of MongoliaUlaanbaatar 14200Mongolia Department of Mechatronics Convergence Engineering College of Future ConvergenceChangwon National UniversityChangwonGyoungnam 641-773Republic of Korea Graduate School of Convergence on Culture Technology Changwon National UniversityChangwonGyoungnam 641-773Republic of Korea

Characteristics of spherical particles on copper powder and changing sizes were studied in a ball mill under various experimental conditions,such as different ball diameters,high rotation speeds,and milling times,using a discrete element method(DEM)*** experiment has investigated the characteristics of spherical particle morphology evolution involved in the mechanical alloying of copper *** morphological evolution of the copper particle was analyzed using scanning electron microscopy(SEM).A spherical copper particle was shown with a roundness value using imageJ *** DEM was used to simulate the ball motion in a planetary ball mill,and the impact energy and shear energy generated during the collision were analyzed to estimate the contact number between the ball and the ball ***,as the size of the ball decreased,the number of ball-to-ball and ball-to-wall contacts increased accordingly,and the spherical shape of the copper powder changed.

关键词： Planetary ball mill DEM simulation Spherical particle morphology Copper powder Ball diameter

Investigation of the nutritional and functional roles of a combinational use of xylanase and β-glucanase on intestinal health and growth of nursery pigs

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Journal of Animal Science and Biotechnology 2024年第5期15卷 1932-1950页

作者： Hyunjun choi Yesid Garavito Duarte Guilherme A.M.Pasquali sung Woo Kim Department of Animal Science North Carolina State University116 Polk HallCampus Box 7621RaleighNC 27695USA BASF SE Ludwigshafen 67056Germany

Background Xylanase andβ-glucanase combination(XG)hydrolyzes soluble non-starch polysaccharides that are anti-nutritional *** study aimed to evaluate the effects of increasing levels of XG on intestinal health and growth performance of nursery *** Forty pigs(6.5±0.4 kg)were assigned to 5 dietary treatments and fed for 35 d in 3 phases(11,9,and 15 d,respectively).Basal diets mainly included corn,soybean meal,and corn distiller's dried grains with solubles,contained phytase(750 FTU/kg),and were supplemented with 5 levels of XG at(1)0,(2)280 TXU/kg xylanase and 125 TGU/kgβ-glucanase,(3)560 and 250,(4)840 and 375,or(5)1,120 and 500,*** performance was *** d 35,all pigs were euthanized and jejunal mucosa,jejunal digesta,jejunal tissues,and ileal digesta were collected to determine the effects of increasing XG levels and XG intake on intestinal *** Increasing XG intake tended to quadratically decrease(P=0.059)viscosity of jejunal digesta(min:1.74 m Pa·s at 751/335(TXU/TGU)/kg).Increasing levels of XG quadratically decreased(P<0.05)Prevotellaceae(min:0.6%at 630/281(TXU/TGU)/kg)in the jejunal *** XG intake quadratically increased(P<0.05)Lactobacillaceae(max:40.3%at 608/271(TXU/TGU)/kg)in the jejunal *** XG intake quadratically decreased(P<0.05)Helicobacteraceae(min:1.6%at 560/250(TXU/TGU)/kg)in the jejunal *** levels of XG tended to linearly decrease(P=0.073)jejunal Ig G and tended to quadratically increase(P=0.085)jejunal villus height to crypt depth ratio(max:2.62 at 560/250(TXU/TGU)/kg).Increasing XG intake tended to linearly increase the apparent ileal digestibility of dry matter(P=0.087)and ether extract(P=0.065).Increasing XG intake linearly increased(P<0.05)average daily *** A combinational use of xylanase andβ-glucanase would hydrolyze the non-starch polysaccharides fractions,positively modulating the jejunal mucosa-associated *** intake of

关键词： Glucanase Growth performance Intestinal health Nursery pigs Xylanase

TEAM:Transformer Encoder Attention Module for Video Classification

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Computer Systems Science & Engineering 2024年第2期48卷 451-477页

作者： Hae sung Park Yong Suk choi Department of Artificial Intelligence Hanyang UniversitySeoulKorea Department of Computer Science Hanyang UniversitySeoulKorea

Much like humans focus solely on object movement to understand actions,directing a deep learning model’s attention to the core contexts within videos is crucial for improving video *** the recent study,Video Masked Auto-Encoder(VideoMAE)employs a pre-training approach with a high ratio of tube masking and reconstruction,effectively mitigating spatial bias due to temporal redundancy in full video *** steers the model’s focus toward detailed temporal ***,as the VideoMAE still relies on full video frames during the action recognition stage,it may exhibit a progressive shift in attention towards spatial contexts,deteriorating its ability to capture the main spatio-temporal *** address this issue,we propose an attention-directing module named Transformer Encoder Attention Module(TEAM).This proposed module effectively directs the model’s attention to the core characteristics within each video,inherently mitigating spatial *** TEAM first figures out the core features among the overall extracted features from each *** that,it discerns the specific parts of the video where those features are located,encouraging the model to focus more on these informative ***,during the action recognition stage,the proposed TEAM effectively shifts the VideoMAE’s attention from spatial contexts towards the core spatio-temporal *** attention-shift manner alleviates the spatial bias in the model and simultaneously enhances its ability to capture precise video *** conduct extensive experiments to explore the optimal configuration that enables the TEAM to fulfill its intended design purpose and facilitates its seamless integration with the VideoMAE *** integrated model,i.e.,VideoMAE+TEAM,outperforms the existing VideoMAE by a significant margin on Something-Something-V2(71.3%vs.70.3%).Moreover,the qualitative comparisons demonstrate that the TEAM encourages the model to disregard insignificant featur

关键词： Video classification action recognition vision transformer masked auto-encoder

Bidirectional rotating direct-current triboelectric nanogenerator with self-adaptive mechanical switching for harvesting reciprocating motion

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International Journal of Extreme Manufacturing 2024年第4期6卷 324-335页

作者： Donghan Lee Joonmin Chae Sumin Cho Jong Woo Kim Awais Ahmad Mohammad Rezaul Karim Moonwoo La sung Jea Park Dongwhi choi Department of Mechanical Engineering(Integrated Engineering Program) Kyung Hee University1732 Deogyeong-daeroYonginGyeonggi 17104Republic of Korea Department of Chemistry University of LahoreLahorePakistan Department of Mechanical Engineering College of EngineeringKing Saud UniversityRiyadh 11421Saudi Arabia School of Mechanical Engineering Korea University of Technology and Education1600 Chungjeol-roCheonanChungnam 31253Republic of Korea

Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic ***,owing to the working mechanisms of conventional DC TENGs,generating a stable DC output from reciprocating motion remains a ***,we propose a bidirectional rotating DC TENG(BiR-TENG),which can generate DC outputs,regardless of the direction of rotation,from reciprocating *** distinct design of the BiR-TENG enables the mechanical rectification of the alternating current output into a rotational-direction-dependent DC ***,it allows the conversion of the rotational-direction-dependent DC output into a unidirectional DC output by adapting the configurations depending on the rotational *** to these tailored design strategies and subsequent optimizations,the BiR-TENG could generate an effective unidirectional DC *** of the BiR-TENG for the reciprocating motions of swinging doors and waves were demonstrated by harnessing this *** study demonstrates the potential of the BiR-TENG design strategy as an effective and versatile solution for energy harvesting from reciprocating motions,highlighting the suitability of DC outputs as an energy source for electronic devices.

关键词： direct-current triboelectric nanogenerator mechanical rectification self-adaptive mechanical design harvesting reciprocation motion

Random pinhole attenuator for high-power laser beams

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High Power Laser Science and Engineering 2024年第3期12卷 116-121页

作者： Seong Cheol Park Hyeok Yun Jin Woo Yoon Seong Ku Lee Jae Hee sung Il Woo choi Chang Hee Nam Kyung Taec Kim Department of Physics and Photon Science Gwangju Institute of Science and TechnologyGwangjuRepublic of Korea Center for Relativistic Laser Science Institute for Basic ScienceGwangjuRepublic of Korea Advanced Photonics Research Institute Gwangju Institute of Science and TechnologyGwangjuRepublic of Korea

The intensity attenuation of a high-power laser is a frequent task in the measurements of optical *** intensity can be attenuated by inserting an optical element,such as a partial reflector,polarizer or absorption *** devices are,however,not always easily applicable,especially in the case of ultra-high-power lasers,because they can alter the characteristics of a laser beam or become easily *** this study,we demonstrated that the intensity of a laser beam could be effectively attenuated using a random pinhole attenuator(RPA),a device with randomly distributed pinholes,without changing the beam *** this device,a multi-PW laser beam was successfully attenuated and the focused beam profile was measured without any alterations of its *** addition,it was confirmed that the temporal profile of a laser pulse,including the spectral phase,was ***,the RPA possesses significant potential for a wide range of applications.

关键词： high-power laser intensity attenuation laser diagnostics

Unraveling the Harmonious Coexistence of Ruthenium States on a Self-Standing Electrode for Enhanced Hydrogen Evolution Reaction

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Energy & Environmental Materials 2024年第6期7卷 303-311页

作者： Joonhee Ma Jin Hyuk Cho Chaehyeon Lee Moon sung Kang sungkyun choi Ho Won Jang Sang Hyun Ahn Seoin Back Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoul 02841Korea Department of Chemical and Biomolecular Engineering Institute of Emergent MaterialsSogang UniversitySeoul 04107Korea Department of Cogno-Mechatronics Engineering College of Nanoscience and NanotechnologyPusan National UniversityBusan 46241Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Korea School of Chemical Engineering and Material Science Chung-Ang UniversitySeoul 06974Korea

The development of cost-effective,highly efficient,and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction(HER).Herein,a simplified synthesis protocol was designed to achieve a self-standing electrode,composed of activated carbon paper embedded with Ru single-atom catalysts and Ru nanoclusters(ACP/Ru_(SAC+C))via acid activation,immersion,and high-temperature *** initio molecular dynamics(AIMD)calculations are employed to gain a more profound understanding of the impact of acid activation on carbon ***,the coexistence states of the Ru atoms are confirmed via aberration-corrected scanning transmission electron microscopy(AC-STEM),X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy(XAS).Experimental measurements and theoretical calculations reveal that introducing a Ru single-atom site adjacent to the Ru nanoclusters induces a synergistic effect,tuning the electronic structure and thereby significantly enhancing their catalytic ***,the ACP/Ru_(SAC+C)exhibits a remarkable turnover frequency(TOF)of 18 s^(−1)and an exceptional mass activity(MA)of 2.2 A mg^(−1),surpassing the performance of conventional Pt *** self-standing electrode,featuring harmoniously coexisting Ru states,stands out as a prospective choice for advancing HER catalysts,enhancing energy efficiency,productivity,and selectivity.

关键词： electrocatalysis electronic coupling effect hydrogen evolution reaction selfstanding electrode

Submicron Ag-coated Cu particles as filler in sintering paste: Suppression of Ag dewetting and improvement of sinterability by surface modification using stearic acid

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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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Stable immobilization of lithium polysulfides using three-dimensional ordered mesoporous Mn_(2)O_(3) as the host material in lithium-sulfur batteries

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Carbon Energy 2024年第6期6卷 99-112页

作者： sung Joon Park Yun Jeong choi Hyun-seung Kim Min Joo Hong Hongjun Chang Janghyuk Moon Young-Jun Kim Junyoung Mun Ki Jae Kim Department of Energy Science Sungkyunkwan UniversitySuwonGyeonggi-doRepublic of Korea Department of Energy Engineering Konkuk UniversitySeoulRepublic of Korea Advanced Batteries Research Center Korea Electronic Technology InstituteSeongnamRepublic of Korea Department of Future Energy Engineering Sungkyunkwan UniversitySuwonRepublic of Korea Department of Energy Systems Engineering Chung-Ang UniversitySeoulRepublic of Korea SKKU Advanced Institute of Nanotechnology Sungkyunkwan UniversitySuwonGyeonggi-doRepublic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwonRepublic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwonRepublic of Korea

Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy ***,the dissolution of long-chain polysulfides into the electrolyte during the charge and discharge process(“shuttle effect”)results in fast capacity fading and inferior electrochemical *** this study,Mn_(2)O_(3)with an ordered mesoporous structure(OM-Mn_(2)O_(3))was designed as a cathode host for LSBs via KIT-6 hard templating,to effectively inhibit the polysulfide shuttle ***-Mn_(2)O_(3)offers numerous pores to confine sulfur and tightly anchor the dissolved polysulfides through the combined effects of strong polar-polar interactions,polysulfides,and sulfur chain *** OM-Mn_(2)O_(3)/S composite electrode delivered a discharge capacity of 561 mAh g^(-1) after 250 cycles at 0.5 C owing to the excellent performance of OM-Mn_(2)O_(3).Furthermore,it retained a discharge capacity of 628mA h g^(-1) even at a rate of 2 C,which was significantly higher than that of a pristine sulfur electrode(206mA h g^(-1)).These findings provide a prospective strategy for designing cathode materials for high-performance LSBs.

关键词： host material lithium-sulfur battery ordered mesoporous structure shuttle effect transition-metal oxides