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Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

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中国有色金属学会会刊：英文版 2012年第S3期22卷 585-595页

作者： Jung-Min lee Chan-Joo lee Kyung-Hun lee Byung-Min KIM Dongnam Regional Division Korea Institute of Industrial Technology Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the ***,this indirect measurement occasionally leads to inaccurate properties of the indented *** objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation *** relations between the residual indentation profile and n value of the indented material were identified by dimensional ***,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and *** parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after *** were subsequently characterized as dimensionless functions using n and E/σr ***,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

关键词： nano-indentation pile-up sink-in strain hardening exponent FE simulation

The effect of the dopant's reactivity for high-performance 2D MoS2 thin-film transistor

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Nano Research 2021年第1期14卷 198-204页

作者： Hanleem lee Sora Bak Joosung Kim Hyoyoung lee Center for Integrated Nanostructure Physics(CINAP) Institute for Basic Science(IBS)Suwon 16419Republic of Korea Department ofChem istryy Sungkyunkwan University Suwon 16419Republic of Korea Department of Energy Science Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Biophysics Sungkyunkwan UniversitySuwon 16419Republic of Korea

There are many studies on the solution-processed thin-film transistor(TFT)using transition metal dichalcogenide(TMD)***,it is hard to control the electrical property of chemically exfoliated TMD materials compared to the chemical vapor deposition *** investigation into the electrical modulation behavior of exfoliated two-dimensional(2D)material is important tofabricate weH-modulated electronic devices via solution ***,we report the effects of reactivity of organic dopants on MoS2 and investigate how the chemical doping behavior influences the electrical properties of *** band state of dopants,which is related to the electron-withdrawing and donating behavior of chemical dopant,provides a proportional shift in the threshold voltages(Vth)of their field-effect transistors(FETs).However,on/off current ratio(Ion/Ioff)and mobility(μ)are strongly influenced by the defect density depending on the reactivity of doping reaction,rather than the band state of organic *** the in-depth study on the doping reaction,we fabricate a FET and a TFT,having high mobility and a relatively high on/off ratio(10^(4))using a solution process.

关键词： 2D materials functionalization thin-film transistor doping defect

Catalysts for electrochemical ammonia oxidation:Trend,challenge,and promise

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Science China Materials 2022年第12期65卷 3334-3352页

作者： Sol A lee Mi Gyoung lee Ho Won Jang Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Electrical and Computer Engineering University of TorontoToronto M5S 3G4OntarioCanada Advanced Institute of Convergence Technology Seoul National UniversitySuwon 16229Republic of Korea

Developing sustainable and clean energy technology is critial to address the current energy and environmental *** an energy carrier,hydrogen has been getting attention due to its abundance,high energy density,and zero carbon *** to the difficulty of hydrogen storage and transport,the electro-oxidation of ammonia shows great potential for renewable energy since it satisfies both energy supply and environmental protection as a carbon-free fuel with high hydrogen ***,ammonia electro-oxidation is a sluggish reaction and shows low *** the complicated mechanism and intermediates is conducive to developing efficient electrocatalysts with high catalytic activity and *** review begins with the ammonia oxidation technologies and their *** two typical mechanisms for ammonia electro-oxidation,Oswin-Salomon mechanism and Gerischer-Mauerer mechanism,are discussed,and attention to the poisoning species is ***,the electrocatalysts for ammonia reaction are classified into Pt-based catalysts and non-noble metal-based catalysts,and their performances are reviewed with various *** on the progress on the electrochemical ammonia oxidation catalysts,the challenges and future insight on ammonia oxidation reaction are discussed and proposed.

关键词： NH3 oxidation reaction electrocatalysts green hydrogen

Cu^+-incorporated TiO_2 overlayer on Cu_2O nanowire photocathodes for enhanced photoelectrochemical conversion of CO_2 to methanol

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Journal of Energy Chemistry 2018年第1期27卷 264-270页

作者： Kangha lee Seokwon lee Hyunjin Cho Sunil Jeong Whi Dong Kim Sooho lee Doh C.lee Department of Chemical and Biomolecular Engineering(BK21+program) KAIST Institute for the NanocenturyKorea Advanced Institute of Science and Technology(KAIST)

In this paper, we report photoelectrochemical（PEC） conversion of carbon dioxide（CO_2） using photocathodes based on Cu_2O nanowires（NWs） overcoated with Cu~＋-incorporated crystalline TiO_2（TiO_2–Cu~＋）shell. Cu_2O NW photocathodes show remanent photocurrent of 5.3% after 30 min of PEC reduction of CO_*** coating Cu_2O with TiO_2–Cu~＋ overlayer, the remanent photocurrent is 27.6%, which is an increase by5.2 fold. The charge transfer resistance of Cu_2O/TiO_2–Cu~＋ is 0.423 k/cm2, whereas Cu_2O photocathode shows resistivity of 0.781 k/cm2 under irradiation. Mott–Schottky analysis reveals that Cu~＋ species embedded in TiO_2 layer is responsible for enhanced adsorption of CO_2 on TiO_2 surface, as evidenced by the decrease of capacitance in the Helmholtz layer. On account of these electrochemical and electronic effects by the Cu~＋ species, the Faradaic efficiency（FE） of photocathodes reaches as high as 56.5% when TiO_2–Cu~＋ is added to Cu_2O, showing drastic increase from 23.6% by bare Cu_2O photocathodes.

关键词： Photoelectrochemical CO2 reductionMethanol generation Copper oxide Titanium dioxide Cu+ catalyst

Effect of processing temperatures on characteristics of surface layers of low temperature plasma nitrocarburized AISI 204Cu austenitic stainless steel

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中国有色金属学会会刊：英文版 2012年第S3期22卷 678-682页

作者： Insup lee Department of Advanced Materials Engineering Dongeui University

The influence of processing temperatures on the surface characteristics of AISI 204Cu austenitic stainless steel was investigated during a low temperature plasma *** resultant layer was a dual-layer structure,which comprises a N-enriched layer on the top of C-enriched *** surface hardness and the layer thickness increase up to about HV 0.05 1000 and 20μm with increasing *** specimen treated at 400°C shows a much enhanced corrosion resistance compared to the untreated steel.A loss in corrosion resistance was observed for specimens treated at temperatures above 430°C due to the formation of Cr2N.

关键词： low temperature plasma nitrocarburizing corrosion resistance expanded austenite AISI 204Cu stainless steel hardness.

CONET： a virtual human system-centered platform for drug discovery

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Frontiers of Computer Science 2018年第1期12卷 1-3页

作者： Doheon lee Bio-Synergy National Research Center Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Korea

One of the most promising approaches to overcome the cur- rent limits of new drug development is to utilize natural prod- ucts with known empirical efficacy, i.e., reverse pharmacol- ogy [ 1,2]. Natural product-based drugs can be classified into two categories, natural product-derived compounds （NPC） and natural product extracts （NPE）. NPC means pure com- pounds derived from natural products. Aspirin from willow trees and Taxol from pacific yew trees are famous examples of the NPC drugs.

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A structural relationship between place attachment and intention to conserve landscapes–a case study of Harz National Park in Germany

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Journal of Mountain Science 2017年第5期14卷 998-1007页

作者： Dukjae lee Ju-Hyoung lee Department of Forest Resources University of Daegu Department of Forest Resources Yeungnam University

Place attachment is an important motivation for people to spend more time outdoors and to protect *** study explores visitors' intention to conserve natural landscapes based on the relationship with their place attachment to National Park landscape. Structural equation modelling(SEM) was used to determine the relationship between landscape conservation and place attachment. A survey with a structured questionnaire was administered to visitors to the seven designated hiking courses of Harz National Park in Germany. The path coefficient of 0.77 revealed that place dependence positively and significantly affected place attachment, whereas place identity did not. Place attachment had a significant effect on both affective appraisals and visiting satisfaction. Higher place attachment led to higher emotional reaction to landscapes on site and higher satisfaction of visiting the park. Among the variables, visiting satisfaction, but not affective appraisals, played a statistically significant mediating role between place attachment and conservation intention. With a path coefficient of 0.86, conservation intention was highly affected by visiting satisfaction. These results suggest that the managers of National Parks should focus on increasing visiting satisfaction based on how visitors are emotionally bonded with their visiting places, in order to enhance the intentions to conserve the landscape of the visitors to National Parks.

关键词： Place attachment Sense of place Mountain forests Structural Equation Model Landscape preference

Rigid reflections and Kac-Moody algebras

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Science China Mathematics 2019年第7期62卷 1317-1330页

作者： Kyu-Hwan lee Kyungyong lee Department of Mathematics University of Connecticut Storrs CT 06269 USA Department of Mathematics University of Nebraska-Lincoln Lincoln NE 68588 USA Korea Institute for Advanced Study Seoul 02455 Republic of Korea

Given any Coxeter group, we define rigid reflections and rigid roots using non-self-intersecting curves on a Riemann surface with labeled curves. When the Coxeter group arises from an acyclic quiver, they are related to the rigid representations of the quiver. For a family of rank 3 Coxeter groups, we show that there is a surjective map from the set of reduced positive roots of a rank 2 Kac-Moody algebra onto the set of rigid reflections. We conjecture that this map is bijective.

关键词： Coxeter groups rigid reflections rigid roots non-self-crossing curves Kac-Moody algebras

Feature-based multiresolution techniques for product design

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第9期7卷 1535-1543页

作者： lee Sang Hun lee Kunwoo School of Mechanical and Automotive Engineering Kookmin University Seoul 136-702 Korea School of Mechanical and Aerospace Engineering Seoul National University Seoul 151-742 Korea

3D computer-aided design (CAD) systems based on feature-based solid modelling technique have been widely spread and used for product design. However, when part models associated with features are used in various downstream applications, simplified models in various levels of detail (LODs) are frequently more desirable than the full details of the parts. In particular, the need for feature-based multiresolution representation of a solid model representing an object at multiple LODs in the feature unit is increasing for engineering tasks. One challenge is to generate valid models at various LODs after an arbitrary rearrangement of features using a certain LOD criterion, because composite Boolean operations consisting of union and subtraction are not commutative. The other challenges are to devise proper topological framework for multiresolution representation, to suggest more reasonable LOD criteria, and to extend applications. This paper surveys the recent research on these issues.

关键词： Multiresolution Level of detail (LOD) Feature Solid Non-manifold