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Oxygen vacancy engineering for tuning the catalytic activity of LaCoO_(3) perovskite

Journal of Rare Earths 2024年第3期42卷 506-514,I0003页

作者： Jeong Hyun Cho Minjae Kim Inchan Yang kyung tae park Chang Houn Rhee Hai Woong park Ji Chul Jung Department of Chemical Engineering Myongji UniversityYongin 17058Republic of Korea Institute of Advanced Composite Materials Korea Institute of Science and TechnologyWanju-gunJeollabuk-do 55324Republic of Korea Iron&Steel Process Engineering Research Group POSCOPohang 37859Republic of Korea Hydrogen Research Center Research Institute of Industrial Science&Technology(RIST)Pohang 37673Republic of Korea

Herein, we attempted to engineer oxygen vacancies on the surface of LaCoO_(3) perovskite through simple post-treatments(acid or reductive thermal treatments). Acid treatment induces oxygen vacancies through the selective etching of the La cations, whereas thermal treatment in a reducing atmosphere generates oxygen vacancies by directly removing lattice oxygen. The characterization results confirm that the number of surface oxygen vacancies, which are crucial in various catalytic oxidation reactions,considerably increases in the LaCoO_(3) catalysts treated with acid or reducing gas. Acid treatment enriches the oxygen vacancies while maintaining the structure of the LaCoO_(3) catalysts, which can not be achieved through reductive thermal treatment. Therefore, the acid treatment is considered a promising technique for oxygen vacancy engineering of perovskite catalysts for tuning their catalytic activities. Furthermore,the catalytic activities of the posttreated LaCoO_(3) catalysts for CO oxidation were evaluated and are noted to be considerably better than those of the pristine LaCoO_(3) catalyst due to their abundant oxygen vacancies. Consequently, we conclude that the oxygen vacancies of perovskite catalysts can be effectively engineered via two simple methods and play a significant role in CO oxidation.

关键词： LaCoO_(3)perovskite Acid treatment Reductive thermal treatment Oxygen vacancy CO oxidation Rare earths

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Effect of Post-Rolling after ECAP on Superplastic Behavior of Commercial Al-Mg Alloy

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Journal of Rare Earths 2004年第Z2期22卷 53-56页

作者： Dong Hyuk Shin Byung Du Ahn Hyun Soo Woo Kyeom Kim kyung-tae park Department of Metallurgy and Materials Science Hanyang UniversityAnsan 425-791Korea Department of Metallurgy and Materials ScienceHanyang UniversityAnsan 425-791Korea Department of Metallurgy and Materials ScienceHanyang UniversityAnsan 425-791Korea Department of Metallurgy and Materials ScienceHanyang UniversityAnsan 425-791Korea Division of Advanced Materials Science & EngineeringHanbat National UniversityTaejon 305-719Korea

A commercial Al-Mg alloy was subjected to equal channel angular pressing of 4 passes with and without postrolling, and the effects of post-rolling on the deformation characteristics of the alloy at 723 K were examined. Post-rolling was found to influence the deformation behavior significantly. The deformation behavior of the alloy processed only by equal channel angular pressing was characterized by (a) localized deformation indicated by severe surface prominence and depression, (b) the strain rate sensitivity of 0.33, and (c) moderate high strain rate superplastic elongations. By contrast, that of the alloy processed by equal channel angular pressing and post-rolling (70 % thickness reduction) was manifested by (a) uniform deformation associated with grain boundary sliding throughout the sample, (b) a sigmoidal behavior showing the strain rate sensitivity of 0.45 at the intermediate strain rates in the logarithmic stress-strain rate curve, and (c) very large high strain rate superplastic elongations.

关键词： high superplasticity equal channel angular pressing rolling deformation mechanisms rare earths

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Scheduling of Logistics for Polarizer Manufacturing

Scheduling of Logistics for Polarizer Manufacturing

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The 12th Asian Pacific Confederation of Chemical Engineering Congress

作者： kyung tae park Jun-Hyung Ryu Ho-kyung Lee In-Beum Lee Department of Chemical Engineering PostechPohangKorca LG Chem Ltd./ Research ParkDeajeonSouth Korea Department of Chemical Engineering PostcchPohangKorca

This paper presents a scheduling model for logistics of *** production can be divided into front-end and back-end *** the front-end process is mainly located in technical oriented sites,the back-end is located in sites where cheaper labor is *** front- end process produces intermediate *** completion of the front-end process,intermediate films are then transferred to the back-end *** back-end process produces finished Polar- izer using intermediate films.

关键词： polarizer core scenario-based approach

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Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

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Journal of Energy Chemistry 2025年第1期100卷 245-258页

作者： Gaeun Lee Yong Nam Ahn Seongjoon So Chanwoo park Jong-Seong Bae taehyun park Il tae Kim Jaehyun Hur School of Chemical Biological and Battery Engineering Gachon University Seongnam Busan Center Korea Basic Science Institute

Aqueous Zn-ion batteries （AZIBs） have received considerable attention owing to their various advantages such as safety,low cost,simple battery assembly conditions,and high ionic ***,they still suffer from serious problems,including uncontrollable dendrite growth,corrosion,hydrogen evolution reaction （HER） from water decomposition,electrode passivation,and unexpected *** creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these ***,we propose the use of a perovskite CaTiO3（CTO） protective layer on Zn（CTO@Zn） as a promising approach for improving the performance of *** CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant （εr=180） and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn2+ions in the CTO *** avoiding the direct contact of the Zn anode with the electrolyte solution,the uneven dendrite growth,corrosion,parasitic side reactions,and HER are mitigated,while CTO retains its mechanical and chemical robustness during ***,CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare ***@Zn shows steady overpotential （～68 m V） for 1500 h at 1 mA cm-2/0.5 mA h cm-2,excelling bare ***,when paired with the V2O5-C cathode,the CTO@Zn//V2O5-C full battery delivers 148.4 mA h g-1（based on the mass of the cathode） after 300 *** study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

关键词： Artificial layer Dielectric constant Zn metal anode Zinc aqueous battery

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Effect of Fe_2P in LiFePO_4/Fe_2P composite on electrochemical properties synthesized by MA and control of heat condition

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Rare Metals 2006年第Z2期25卷 179-183页

作者： park Jong Suk LEE kyung tae LEE kyung Sub Department of Material Science and Engineering Hanyang University Seoul 133-731 Korea

In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying. The discharge capacity of the fast cooled was 83 mAh·g-1 and the slow cooled 121 mAh·g-1. The particle size of the synthesized powder was examined by transmission electron microscopy and distribution of Fe2P was characterized using scanning electron microscopy (SEM). In addition, two-step heat treatment was carried out for better distribution of Fe2P. X-ray diffraction (XRD) and Rietveld refinement reveal that LiFePO4/Fe2P composite consists of 95.77% LiFePO4 and 4.33% of Fe2P.

关键词： LiFePO4/Fe2P composite mechanical alloying heat treatment discharge capacity

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Electrochemically metal-doped reduced graphene oxide films:Properties and applications

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Journal of Materials Science & Technology 2020年第5期40卷 72-80页

作者： Myung-Sic Chae tae Ho Lee kyung Rock Son tae Hoon park Kyo Seon Hwang tae Geun Kim School of Electrical Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841South Korea Department of Clinical Pharmacology and Therapeutics College of MedicineKyung Hee UniversitySeoul 02447South Korea

The fine control of doping levels in graphene materials such as reduced graphene oxide(RGO)is important to properly manipulate their ambipolar transport characteristics for various device ***,conventional doping methods involve complex chemical reactions,large-scale doping processes,and poor ***,a simple and controllable electrochemical doping treatment(EDT),performed via the conductive channels created at the RGO surface by the application of an electric field,is introduced to tailor the electrical properties of RGO films.X-ray photoelectron spectroscopy and Raman spectroscopy measurements are performed to detect the presence of Ni atoms in RGO films after the EDT(EDT-RGO).Then,EDT-RGO field-effect transistors(FETs)are fabricated with different doping areas(0 to 100%fractional area)on the RGO active channel to investigate the effect and selective-area doping capability of the *** to p-type doping compensation by the intercalated Ni atoms,the electron mobility of the EDT-RGO FET decreases from 1.40 to 0.12 cm2 V-1s-1 compared with that of the undoped RGO-FET,leading to the conversion from ambipolar to unipolar p-type transfer characteristics.

关键词： Reduced graphene oxide Electrochemical doping treatment Electrical breakdown process Field-effect transistor

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Arterial stiffness expressed as brachial–ankle pulse wave velocity and gait assessment independent of lower extremity strength:a cross-sectional study in the older men population

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Journal of Geriatric Cardiology 2023年第2期20卷 91-99页

作者： tae kyung Yoo Seunghee Lee Sae-Jong park Jong-Young Lee Department of Medicine MetroWest Medical CenterFraminghamUSA Department of Physical Education Korea UniversitySeoulSouth Korea Division of Sports Science Korea Institute of Sport ScienceSeoulSouth Korea Division of Cardiology Department of Internal MedicineKangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoulSouth Korea

BACKGROUND Older men are more vulnerable to fatal falls than women,and gait disturbances contribute to the risk of *** have assessed the association between arterial stiffness and gait dysfunction,but the results have been *** study aimed to conduct a cross-sectional analysis to evaluate the association between brachial–ankle pulse wave velocity(baPWV)and gait assessment in older *** Data from the 2014–2015 Korea Institute of Sport Science Fitness Standards project were used for the *** inclusion criteria were men aged>65 years with gait assessment[the 30-s chair stand test(30s-CST),the timed up and go(TUG)test,the figure-of-8 walk(F8W)test,the 2-min step test(2MST),and the 6-min walk test(6MWT)]and baPWV measurement *** linear regression analysis was conducted with multiple confounding factor adjustments,including lower extremity isometric *** A total of 291 participants were included in the *** mean age was 71.38±4.40 *** mean values were as follows:(1)30s-CST,17.48±5.00;(2)TUG test,6.01±1.10 s;(3)F8W test,25.65±4.71 s;(4)2MST,102.40±18.83 per 2 min;and(5)6MWT,500.02±85.65 *** multivariable adjustment,baPWV was associated with the 6MWT(β=−0.037,95%CI:−0.072–−0.002),TUG test(β=0,95%CI:0.000–0.001),and F8W test(β=0.002,95%CI:0.000–0.004).baPWV was not associated with the 30s-CST and *** The current study showed a statistically significant association between gait assessments and arterial stiffness,independent of lower extremity ***,this association was *** prospective studies are needed to elucidate the complex relationship between arterial stiffness and gait dysfunction.

关键词： stiffness sectional pulse

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Calcium-dependent proteasome activation is required for axonal neurofilament degradation

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Neural Regeneration Research 2013年第36期8卷 3401-3409页

作者： Joo Youn park So Young Jang Yoon kyung Shin Duk Joon Suh Hwan tae park Department of Physiology Mitochondria Hub Regulation Center College of Medicine Dong-A University

Even though many studies have identified roles of proteasomes in axonal degeneration, the mo- lecular mechanisms by which axonal injury regulates proteasome activity are still unclear. In the present study, we found evidence indicating that extracellular calcium influx is an upstream regulator of proteasome activity during axonal degeneration in injured peripheral nerves. In degenerating axons, the increase in proteasome activity and the degradation of ubiquitinated proteins were sig- nificantly suppressed by extracellular calcium chelation. In addition, electron microscopic findings revealed selective inhibition of neurofilament degradation, but not microtubule depolymerization or mitochondrial swelling, by the inhibition of calpain and proteasomes. Taken together, our findings suggest that calcium increase and subsequent proteasome activation are an essential initiator of neurofilament degradation in Wallerian degeneration.

关键词： neural regeneration peripheral nerve injury neurofilament degradation sciatic nerve calcium calpain mitochondria microtubule depolymerization axon axon degeneration neuroregeneration

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Cavity-Suppressing Electrode Integrated with Multi-Quantum Well Emitter:A Universal Approach Toward High-Performance Blue TADF Top Emission OLED

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Nano-Micro Letters 2022年第4期14卷 75-89页

作者： Il Gyu Jang Vignesh Murugadoss tae Hoon park kyung Rock Son Ho Jin Lee WanQi Ren Min Ji Yu tae Geun Kim School of Electrical Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841Republic of Korea

A novel device structure for thermally activated delayed fluorescence(TADF)top emission organic light-emitting diodes(TEOLEDs)that improves the viewing angle characteristics and reduces the efficiency roll-off is ***,we describe the design and fabrication of a cavity-suppressing electrode(CSE),Ag(12 nm)/WO_(3)(65 nm)/Ag(12 nm)that can be used as a transparent *** the TADF-TEOLED fabricated using the CSE exhibits higher external quantum efficiency(EQE)and improved angular dependency than the device fabricated using the microcavity-based Ag electrode,it suffers from low color purity and severe efficiency *** drawbacks can be reduced by using an optimized multi-quantum well emissive layer(MQW EML).The CSE-based TADF-TEOLED with an MQW EML fabricated herein exhibits a high EQE(18.05%),high color purity(full width at half maximum~59 nm),reduced efficiency roll-off(~46%at 1000 cd m^(−2)),and low angular *** improvements can be attributed to the synergistic effect of the CSE and MQW *** optimized transparent CSE improves charge injection and light outcoupling with low angular dependence,and the MQW EML effectively confines charges and excitons,thereby improving the color purity and EQE *** proposed approach facilitates the optimization of multiple output characteristics of TEOLEDs for future display applications.

关键词： Cavity suppression Multi-quantum well Viewing angle Efficiency roll-off Top emission OLED

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Correlation of Microstructure and Hydrogen Delayed Fracture for 1GPa Steels

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Journal of Iron and Steel Research International 2011年第S1期18卷 252-254页

作者： Hee Jae Kang Ji tae park Soon tae Ahn kyung Mox Cho Nam Hyun Kang Department of Materials Science and Engineering Pusan National UniversityBusan 609-735Korea Samhwa Steel 339-4 Samrak-dongSasang-guBusan 617-825Korea

Automobile industry tries to reduce the weight of automobile using high-strength ***,the high-strength steels are highly susceptible to delayed-fracture caused by hydrogen *** increasing the strength,hydrogen embrittlement is more sensitive to diffusible *** mechanism of delayed-fracture and the relationship with the microstructure and alloying elements are still *** study analyzed the effect of the size and the spheroidization rate for the carbides on hydrogen-induced delayed fracture for 1GPa TS steel.

关键词： hydrogen delayed fracture microstructure spheroidization

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