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Improvement of Shape Recognition Performance of Sendzimir Mill Control Systems Using Echo State Neural Networks

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Journal of Iron and Steel Research International 2014年第3期21卷 321-327页

作者： Jung-hyun PARK Seong-ik HAN Jong-shik KIM School of Mechanical Engineering Pusan National University School of Electrical Engineering Pusan National University

High rigidity twenty-high Sendzimir mills （ZRMs） are widely used for rolling stainless steels, silicon sheets, etc. A ZRM uses a small diameter work roll to produce massive rolling forces. Since a work roll with a small diameter can be bent easily, strips often have complex shapes with mixed quarter and deep edge waves in the shape of plates. In order to solve this problem, fuzzy neural network controls are generally used for shape： recognition in ZRM control systems. Among various neural network types, the multi-layer perceptron （MLP） is typically used in current ZRMs. However, an MLP causes the loss of a large amount of shape recognition data. To improve the shape recognition per- formance of ZRM control systems, echo state networks （ESNs） are proposed to be used. Through simulation re- sults, it is found that shape recognition performance could be improved using the proposed ESN method.

关键词： Sendzimir mill neural network multi-layer perceptron echo state network shape recognition

Yolk-shell-structured （***.s）9S8 solid-solution powders：Synthesis and application as anode materials for Na-ionbatteries

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Nano Research 2017年第9期10卷 3178-3188页

作者： Jung hyun Kim yun Chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea

Multicomponent metal sulfide materials with a yolk–shell structure and a single phase were studied for the first time as anode materials for sodium-ion batteries. Yolk–shell-structured Fe–Ni–O powders with a molar ratio of iron and nickel components of 1/1 were prepared via one-pot spray pyrolysis. The prepared Fe–Ni–O powders were transformed into yolk–shell-structured (Fe0.5Ni0.5)9S8 solid-solution powders via a sulfidation process. The initial discharge and charge capacities of the (Fe0.5Ni0.5)9S8 powders at a current density of 1 A·g−1 were 601 and 504 mA·h·g−1, respectively. The discharge capacities of the (Fe0.5Ni0.5)9S8 powders for the 2nd and 100th cycle were 530 and 527 mA·h·g−1, respectively, and their corresponding capacity retention measured from the 2nd cycle was 99%. The (Fe0.5Ni0.5)9S8 powders had high initial discharge and charge capacities at a low current density of 0.1 A·g−1, and the reversible discharge capacity decreased slightly from 568 to 465 mA·h·g−1 as the current density increased from 0.1 to 5.0 A·g−1. The synergetic effect of the novel yolk–shell structure and the multicomponent sulfide composition of the (Fe0.5Ni0.5)9S8 powders resulted in excellent sodium-ion storage performance.

关键词： metal sulfide multicomponent sulfide yolk–shell sodium-ion batteries spray pyrolysis

Milk protein-shelled gold nanoparticles with gastrointestinally active absorption for aurotherapy to brain tumor

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Bioactive Materials 2022年第2期7卷 35-48页

作者： hyung shik Kim Seung Jae Lee Dong yun Lee Department of Bioengineering College of Engineeringand BK FOUR Biopharmaceutical Innovation Leader for Education and Research GroupHanyang UniversitySeoul04763Republic of Korea Institute of Nano Science and Technology Hanyang UniversitySeoul04763Republic of Korea

Orally absorbable gold nanoparticles(AuNP)having cancer ablation therapy is strongly demanded to treat glioblastoma multiforme(GBM)for patients with its highest incidence ***,we develop a milk protein lactoferrin-conjugated AuNP for its oral absorption and targeting to the GBM through the interaction between lactoferrin(Lf)and lactoferrin receptor(LfR)that is highly expressed in the intestine,blood-brain barrier and *** stability and long circulation of AuNP,glutathione and polyethylene glycol(PEG)is introduced,which is called to *** Lf-PEG-AuNP are orally administered to orthotopic GBM-bearing mice,11-fold and 8-fold higher concentrations of AuNP are measured in bloodstreams and GBM in the brain,respectively,compared with ***,orally administered Lf-PEG-AuNP exhibit an outstanding temperature rise in GBM by irradiating laser and significantly reduce tumor ***,we suggest that the Lf-PEG-AuNP can fundamentally target GBM in the brain through oral absorption,and that its efficient photothermal therapy is possible.

关键词： intestine absorption gastrointestinal

Prediction of Melt Pool Dimension and Residual Stress Evolution with Thermodynamically-Consistent Phase Field and Consolidation Models during Re-Melting Process of SLM

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Computers, Materials & Continua 2021年第1期66卷 87-112页

作者： Kang-hyun Lee Gun Jin yun Department of Aerospace Engineering Seoul National UniversitySeoul08826South Korea Institute of Advanced Aerospace Technology Seoul National UniversitySeoul08826South Korea

Re-melting process has been utilized to mitigate the residual stress level in the selective laser melting(SLM)process in recent ***,the complex consolidation mechanism of powder and the different material behavior after the first laser melting hinder the direct implementation of the re-melting *** this work,the effects of re-melting on the temperature and residual stress evolution in the SLM process are investigated using a thermo-mechanically coupled finite element *** degree of consolidation is incorporated in the energy balance equation based on the thermodynamically-consistent phase-field *** drastic change of material properties due to the variation of temperature and material state is also *** the proposed simulation framework,the single-track scanning is simulated first to predict the melt pool dimension and validate the proposed model with the existing experimental *** obtained thermal histories reveal that the highest cooling rate is observed at the end of the local solidification time which acts as an important indicator for the alleviation of temperature ***,the scanning of a whole single layer that consists of multiple tracks is simulated to observe the stress evolution with several re-melting *** the full melting of powder material in the first scanning process,the increase of residual stress level is observed with one remelting ***,the predicted stress level with the re-melting process shows the variation trend attributable to the accumulated heat in the *** numerical issues and the detailed implementation process are also introduced in this paper.

关键词： Selective laser melting thermo-mechanical analysis Ti-6Al-4V additive manufacturing re-melting residual stress

MOF‑Derived CoSe2@N‑Doped Carbon Matrix Confined in Hollow Mesoporous Carbon Nanospheres as High‑Performance Anodes for Potassium‑Ion Batteries

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Nano-Micro Letters 2021年第1期13卷 123-137页

作者： Su hyun Yang Seung‑Keun Park yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam‑DongSeongbuk‑GuSeoul 136‑713Republic of Korea Department of Chemical Engineering Kongju National University1223‑24 Cheonan‑daeroSeobuk‑guCheonan 31080Republic of Korea

In this work,a novel vacuum-assisted strategy is proposed to homogenously form Metal-organic frameworks within hollow mesoporous carbon nanospheres(HMCSs)via a solid-state *** method is applied to synthesize an ultrafine CoSe2 nanocrystal@N-doped carbon matrix confined within HMCSs(denoted as CoSe2@NC/HMCS)for use as advanced anodes in highperformance potassium-ion batteries(KIBs).The approach involves a solvent-free thermal treatment to form a Co-based zeolitic imidazolate framework(ZIF-67)within the HMCS templates under vacuum conditions and the subsequent *** treatment under vacuum facilitates the infiltration of the cobalt precursor and organic linker into the HMCS and simultaneously transforms them into stable ZIF-67 particles without any *** the subsequent selenization process,the“dual confinement system”,composed of both the N-doped carbon matrix derived from the organic linker and the small-sized pores of HMCS,can effectively suppress the overgrowth of CoSe2 ***,the resulting uniquely structured composite exhibits a stable cycling performance(442 mAh g^−1 at 0.1 A g^−1 after 120 cycles)and excellent rate capability(263 mAh g^−1 at 2.0 A g^−1)as the anode material for KIBs.

关键词： Metal-organic frameworks Hollow mesoporous carbon nanospheres Potassium-ion batteries Cobalt selenides Electrode materials

Carbon-Coated Three-Dimensional MXene/Iron Selenide Ball with Core–Shell Structure for High-Performance Potassium-Ion Batteries

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Nano-Micro Letters 2022年第1期14卷 278-294页

作者： Su hyun Yang yun Jae Lee Heemin Kang Seung-Keun Park yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul 136-713Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726 Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea

Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion ***,similar to most 2D materials,MXene nanosheets easily restack during the electrode preparation,which degrades the electrochemical performance of MXene-based materials.A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional(3D)balls coated with iron selenides and *** strategy involves the preparation of Fe_(2)O_(3)@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization *** 3D structuring effectively prevents interlayer restacking,increases the surface area,and accelerates ion transport,while maintaining the attractive properties of ***,combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite *** resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g^(−1) after 200 cycles at 0.1 A g^(−1) in potassium-ion batteries,corresponding to the capacity retention of 97% as calculated based on 100 *** at a high current density of 5.0 A g^(−1),the composite exhibits a discharge capacity of 169 mAh g^(−1).

关键词： MXene Spray pyrolysis Iron selenide Potassium-ion batteries 3D structures

Suggestion of advanced regression model on friction angle of fault gouge in South Korea

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第6期13卷 1368-1379页

作者： Seong-Woo Moon hyun-Seok yun Yong-Seok Seo Department of Earth and Environmental Sciences Chungbuk National University1 Chungdae-roCheongju-siChungcheongbuk-do28644South Korea

Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low ***,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression *** most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657.

关键词： Fault gouge Friction angle Simple regression analysis Structural equation model analysis Multiple regression analysis

Impact of UV-A Radiation on Erythemal UV and UV-index Estimation over Korea

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Advances in Atmospheric Sciences 2015年第12期32卷 1639-1646页

作者： Sang Seo PARK yun Gon LEE Jung hyun KIM Department of Atmospheric Sciences Yonsei University Department of Atmospheric Sciences Chungnam National University

Because total UV （TUV） in the UV-A region is 100 times higher than in the UV-B region, UV-A is a considerable compo- nent when calculating erythemal UV （EUV） and UV-index. The ratio of EUV to TUV in the UV-A value [EUV（A）/TUV（A）] is investigated to convert the EUV（A） from TUV（A） for broadband observation. The representative value of EUV（A）/TUV（A）, from the simulation study, is 6.9 × 10^- 4 changing from 6.1 ×10^-4 to 7.0 × 10^ -4 as aerosol optical depth, total ozone and solar zenith angle change. By adopting the observational data of EUV（B） and TUV（A） from UV-biometer measurements at Yonsei University [（37.57°N, 126.95°E）, 84 m above sea level], the EUV irradiance increases to 15% of EUV（B） due to the consideration of EUV（A） from the data of TUV（A） observation. Compared to the total EUV observed from the Brewer spec- trophotometer at the same site, the EUV（B） from the UV-biometer observes only 95% of total EUV, and its underestimation is caused by neglecting the effect of UV-A. However, the sum of EUV（B） and EUV（A） [EUV（A＋B）] from two UV-biometers is 10% larger than the EUV from the Brewer spectrophotometer because of the spectral overlap effect in the range 320-340 nm. The correction factor for the overlap effect adjusts 8% of total EUV.

关键词： erythemal UV total UV UV-B UV-biometer

Nanostructured hafnium-doped strontium oxide film for homeotropic/homogeneous convertible liquid crystal alignment depending on the curing temperature

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International Journal of Smart and Nano Materials 2022年第4期13卷 597-611页

作者： Dong hyun Kim Dong Wook Lee Jin Young Oh Jonghoon Won Hae-Chang Jeong Dae-shik Seo IT Nano Electronic Device Laboratory Department of Electrical and Electronic EngineeringYonsei UniversitySeoulRepublic of Korea Department of Smart Manufacturing Engineering Changwon National UniversityChangwonGyeongnamRepublic of Korea Department of Electrical Electronic and Control Engineering Changwon National UniversityChangwonGyeongnamRepublic of Korea

A hafnium strontium oxide(HfSrO)liquid crystal(LC)alignment film was efficiently created through brush coating,and its ability to change the LC alignment direction was confirmed.A brush was applied to HfSrO sol coated on an indium-tin oxide substrate,after which the coating was solidified at var-ious curing *** was confirmed that a directional micro/nanostructure was formed above 280°C due to the shear stresses caused by the movement of the brush *** chemical changes were analyzed by using X-ray photoelectron spectroscopy and contact angle *** the curing temperature increased,the prevalence of oxygen bonds increased and the contact angle decreased,thereby increasing the surface *** anisotropic boundary of the micro-grooves and the van der Waals forces due to an increase in surface energy changed the alignment direction of LC mole-cules from vertical to horizontal,as verified through polarized optical microscopy and pretilt angle ***,the efficiency of the brush-coating method,which dramatically simplifies the LC alignment film process,was *** homeotropic/homogeneous LC alignment property of the HfSrO film produced through brush coating depending on the curing temperature provides an innovative approach for LC alignment.

关键词： Brush coating nanostructure solution process liquid crystal alignment