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Nano-Micro Letters 2023年第6期15卷 1-23页

作者： Horim Lee seung han ryu Suk Jin Kwon Jae ryung Choi Sang‑bok Lee Byeongjin Park Composites Research Division Korea Institute of Materials Science797 ChangwondaeroSeongsan‑GuChangwonGyeongsangnam‑Do 51508Republic of Korea

Although there is a high demand for absorption-dominant electromagnetic interference(EMI) shielding materials for 5G millimeter-wave(mmWave) frequencies, most current shielding materials are based on reflection-dominant conductive materials. While there are few absorption-dominant shielding materials proposed with magnetic materials, their working frequencies are usually limited to under 30 GHz. In this study, a novel multi-band absorption-dominant EMI shielding film with M-type strontium ferrites and a conductive grid is proposed. This film shows ultralow EMI reflection of less than 5% in multiple mmWave frequency bands with sub-millimeter thicknesses, while shielding more than 99.9% of EMI. The ultralow reflection frequency bands are controllable by tuning the ferromagnetic resonance frequency of M-type strontium ferrites and composite layer geometries. Two examples of shielding films with ultralow reflection frequencies, one for 39 and 52 GHz 5G telecommunication bands and the other for 60 and 77 GHz autonomous radar bands, are presented. The remarkably low reflectance and thinness of the proposed films provide an important advancement toward the commercialization of EMI shielding materials for 5G mmWave applications.

关键词： 5G communication MmWave EMI shielding M-type ferrites

Occipital artery bypass importance in unsuitable superficial temporal artery:Two case reports

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World Journal of Clinical Cases 2023年第9期11卷 2091-2097页

作者： Jong-Hwan Hong Sung-Chan Jung han-seung ryu Tae-Sun Kim Sung-Pil Joo Department of Neurosurgery Chonnam National University Hospital and Medical SchoolGwangju 61469South Korea

BACKGROUND Superficial temporal artery-middle cerebral artery(STA-MCA)bypass helps treat cerebral ***,the STA is not available for bypass in some ***,with some technical tips,the authors introduced a bypass technique using the occipital artery(OA).CASE SUMMARY Two female patients complained of *** magnetic resonance imaging(MRI)indicated contralateral infarction from the MCA *** Diamox single photon emission computed tomography or perfusion MRI,the contralateral front parietotemporal reserve was *** transfemoral cerebral angiography,the STA was thin with a weak flow;however,the OA was *** OA-MCA end-to-side extracranial-intracranial bypass surgery was implemented instead of STA because the caliber was too *** postoperative course was uneventful in both cases,with well-maintained bypass patency and neurological stability during *** OA might be an acceptable alternative for MCA cerebral ischemic cases with an unsuitable STA.

关键词： Bypass Occipital artery Superficial temporal artery Cerebral ischemia Case report

Recent progress and future directions of the research on nanoplastic-induced neurotoxicity

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Neural Regeneration Research 2024年第2期19卷 331-335页

作者： seung-Woo han Jinhee Choi Kwon-Yul ryu Department of Life Science University of SeoulSeoulSouth Korea School of Environmental Engineering University of SeoulSeoulSouth Korea

Many types of plastic products,including polystyrene,have long been used in commercial and industrial *** and nanoplastics,plastic particles derived from these plastic products,are emerging as environmental pollutants that can pose health risks to a wide variety of living organisms,including ***,it is not well understood how microplastics and nanoplastics affect cellular functions and induce stress *** can be exposed to polystyrene-microplastics and polystyrene-nanoplastics through ingestion,inhalation,or skin *** ingested plastics are excreted from the body,but inhaled plastics may accumulate in the lungs and can even reach the brain via the nose-to-brain ***-sized polystyrene-nanoplastics can enter cells by endocytosis,accumulate in the cytoplasm,and cause various cellular stresses,such as inflammation with increased pro-inflammatory cytokine production,oxidative stress with generation of reactive oxygen species,and mitochondrial *** induce autophagy activation and autophagosome formation,but autophagic flux may be impaired due to lysosomal *** permanently exposed to polystyrene-nanoplastics,they can be removed from cells by exocytosis and subsequently restore cellular ***,neurons are very susceptible to this type of stress,thus even acute exposure can lead to neurodegeneration without *** review focuses specifically on recent advances in research on polystyrene-nanoplastic-induced cytotoxicity and ***,in this review,based on mechanistic studies of polystyrene-nanoplastics at the cellular level other than neurons,future directions for overcoming the negative effects of polystyrene-nanoplastics on neurons were suggested.

关键词： autophagy cellular stress cytotoxicity endocytosis exocytosis inflammation microplastics nanoplastics neurotoxicity oxidative stress polystyrene

Design,Fabrication,and Analysis of Flapping and Folding Wing Mechanism for a Robotic Bird

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Journal of Bionic Engineering 2020年第2期17卷 229-240页

作者： seung Wan ryu Jong Gu Lee Hyoun Jin Kim Department of Mechanical&Aerospace Engineering and Automation Systems Research Institute Seoul National UniversitySeoul 08826Republic of Korea

Emulating periodic main wing movement of a bird for generating lift and thrust remains a significant challenge in developing a robotic *** sequences of main wing motion are comprised of flapping,folding,bending,and *** this paper,we concentrate on the flapping and folding motion,and design two wing mechanisms based on a 4-bar linkage structure:one is only for Flapping Motion(FM)and the other is for simultaneous Flapping and Folding Motion(FFM)during a wing *** derive relationships between length and angle of links to analyze kinematic characteristics of the mechanisms and conduct an optimization to select the length parameters of links that allow maximization of the flapping *** run a simulation to confirm the performance of the optimized parameters by examining physical properties,and fabricate two wing mechanisms *** particular,the folding motion is achieved without using an additional *** measurements to investigate a lift profile of each mechanism and their quantitative comparison of the performance of both types confirm the benefits of the folding motion in the perspectives of wing frequency and *** expect that our kinematic formulation,design procedures,and comparative measurement results can help develop a wing mechanism to create a truly biomimetic robotic bird.

关键词： biomimetic robotic bird flapping and folding wing mechanism wing kinematics force measurement

Organic solar cells for indoor power generation

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Science China Chemistry 2020年第1期63卷 1-2页

作者： Hwa Sook ryu han Young Woo Department of Chemistry College of Science Korea University

During last decades,organic solar cells(OSCs)have achieved remarkable advancements via extensive studies on the optimization of photovoltaic donor/acceptor(D/A)materials,device fabrication,and the D/A bulk heterojunction *** conversion efficiencies(PCEs)up to〜16%for single junction cells and over 17%PCEs were successfully demonstrated for tandem OSC devices[1,2].OSCs may find real industrial applications soon,including building integrated photovoltaics,portable power sources and indoor power generation for low power consumption electronic devices(i.e.,internet of things(IOT)sensors).Among them,indoor applications have great potentials because OSCs can convert indoor lights into electricity more efficiently compared to inorganic counterparts[3].

关键词： D/A power portable

Surface exsolution and local atomic structure of amorphous CeTiO_x

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Journal of Rare Earths 2019年第2期37卷 160-165页

作者： seung-Hyeon Jo Soonok Kim Jiseung ryu Dae-seung Cho Bora Jeong Heesoo Lee Department of Materials Science and Engineering Pusan National University Department of Naval Architecture & Ocean Engineering Pusan National University Green Materials & Processes Group Ulsan Regional Division Korea Institute of Industrial Technology

We made precipitated nano-ceria(~5 nm) on the surface of the catalyst by heat treatment of Cesupersaturated amorphous CeTiOxto improve the oxygen storage properties of CeO_2. The catalysts were prepared by sol-gel methods and TiO_2 nanoparticles were preferentially generated as a core material to form selective Ce-supersaturated structure on the catalyst surface. Reaction temperature and amount of doping element are optimized to induce selective crystallization of CeO_2. Cee Ce(2 nd shell)bond around 0.38 nm of Ce L3-edge extended X-ray absorption fine structure is reduced and nanostructure of precipitated ceria on the surface is observed by HREM. The catalyst is present as amorphous with precipitated nano-CeO_2 on the surface. The de-NOxefficiency of the catalyst, which has precipitated CeO_2, improves by ~50% owing to the simultaneous reactions of the nano CeO_2 and the amorphous CeTiO_x.

关键词： Ce-Ti oxide Exsolution Amorphous catalyst Local atomic structure De-NO_x efficiency Rare earths

Effect of Plastic Anisotropy on the Formability of Aluminum 6016-T4 Sheet Material

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Chinese Journal of Mechanical Engineering 2017年第3期30卷 625-631页

作者： Young-Suk KIM seung-han YANG kyungpook national university Daegu 41566Republic of Korea

Sheet metal formed of lightweight materials such as aluminum sheeting has received great attention related to the reduction of vehicle emissions. This paper evaluates the anisotropic yield locus using Kuwabara＇s biaxial tensile tester and stretches formability using Hecker＇s hemispheri- cal punch stretching test for aluminum 6016-T4 sheet material. The anisotropic yield locus of the A16016-T4 sheet measured is fitted well by the modified Drucker yield func- tion. Moreover the best fitting to the experimental stress- strain curve from the tensile test was obtained by taking an appropriate hardening model. Analytical study to predict the stretch formability by using Hora＇s Modified Maximum Force Criterion （MMFC） was performed. The predicted forming limit curves （FLC） based on various yield functions were compared with the experiments and discussed.

关键词： Anisotropic yield function AluminumA16016-T4 Biaxial tensile test Forming limit curve

ZnO-Embedded Expanded Graphite Composite Anodes with Controlled Charge Storage Mechanism Enabling Operation of Lithium-Ion Batteries at Ultra-Low Temperatures

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Energy & Environmental Materials 2023年第4期6卷 31-39页

作者： Kun ryu Michael J.Lee Kyungbin Lee seung Woo Lee George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly ***,the lowtemperature performance of conventional graphite anodes is severely hampered by the poor diffusion kinetics of Li ions(Li^(+)).Here,zinc oxide(ZnO) nanoparticles are incorporated into the expanded graphite to improve Li^(+)diffusion kinetics,resulting in a significant improvement in lowtemperature *** ZnO-embedded expanded graphite anodes are investigated with different amounts of ZnO to establish the structurecharge storage mechanism-performance relationship with a focus on lowtemperature *** analysis reveals that the ZnOembedded expanded graphite anode with nano-sized ZnO maintains a large portion of the diffusion-controlled charge storage mechanism at an ultra-low temperature of-50℃ Due to this significantly enhanced Li^(+)diffusion rate,a full cell with the ZnO-embedded expanded graphite anode and a LiNi_(0.88)Co_(0.09)Al_(0.03)O_(2)cathode delivers high capacities of 176 mAh g^(-1)at20℃ and 86 mAh g^(-1)at-50℃ at a high rate of 1 *** outstanding low-temperature performance of the composite anode by improving the Li^(+)diffusion kinetics provides important scientific insights into the fundamental design principles of anodes for low-temperature Li-ion battery operation.

关键词： diffusive and capacitive charge storages expanded graphite composites anode lithium-ion battery low-temperature operation transition metal oxide

Macrophage activation syndrome in children with Kawasaki disease: diagnostic and therapeutic approaches

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World Journal of Pediatrics 2020年第6期16卷 566-574页

作者： seung Beom han Soo-Young Lee Department of Pediatrics Daejeon St.Mary's Hospital.College of MedicineThe Catholic University of Korea64 Daeheung-ro.Jung-guDaejeon 34943Republic of Korea Department of Pediatrics.Bucheon St.Mary's Hospital College of MedicineThe Catholic University of Korea327 Sosa-roWonmi-gu.Bucheon 14647Republic of Korea

Background Macrophage activation syndrome(MAS)is a rare,life-threatening complication of Kawasaki disease(KD).Early recognition and treatment of MAS are very important,but sometimes it is difficult to distinguish MAS from a severe form of *** sources A PubMed search was performed in Clinical Queries using the key terms“macrophage activation syndrome or secondary hemophagocytic lymphohistiocytosis(HLH)”and“Kawasaki disease”.Results KD patients with MAS show high intravenous immunoglobulin(IVIG)resistance and coronary *** is also as high as MAS in other *** fever greater than 10 days is highly associated with development of MAS in *** is observed in more than two-thirds of KD patients with *** is often the earliest laboratory finding of *** is highly specific and sensitive for detecting MAS in KD;so,ferritin levels should be checked if there are unexplained clinical exacerbations in KD *** the under-recognition of MAS in KD,it is prudent to consider resistant KD as occult/subclinical *** KD patients with MAS have good outcomes on immune ***,if KD patients fulfill the HLH-2004 diagnostic criteria,they may undergo longer and more intensive treatment than *** The possible existence of MAS should be taken into account when a KD patient shows persistent fever,splenomegaly,thrombocytopenia,hyperferritinemia,or IVIG *** under-diagnosis of MAS in patients with KD is an important issue to be ***,however,there is a possibility of over-treatment of MAS in patients with KD.

关键词： Macrophage activation syndrome Kawasaki disease Children

Influence of Zn and Mg Alloying on the Corrosion Resistance Properties of Al Coating Applied by Arc Thermal Spray Process in Simulated Weather Solution

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Acta Metallurgica Sinica(English Letters) 2018年第6期31卷 591-603页

作者： han-seung Lee seung-Jun Kwon Jitendra Kumar Singh Mohamed A.Ismail Department of Architectural Engineering Hanyang University Department of Civil Engineering Hannam University Department of Civil and Construction Engineering Faculty of Engineering and ScienceCurtin University Malaysia

In this study,Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process.X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corrosion *** circuit potential（OCP）,electrochemical impedance spectroscopy,and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers（SAE）J2334 solution of varying *** solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited ***,the Al–Mg alloy coating maintained an OCP of approximately-0.911 V versus Ag/Ag Cl in the SAE J2334 solution even after 792 h of *** indicates that it protects the steel sacrificially,whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion *** Al–Mg coating acts as a self-healing coating and provides protection by forming Mg_6Al_2（OH）_（16）CO_3（Al–Mg layered double hydroxides）.Mg_6Al_2（OH）_（16）CO_3has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the *** presence of Zn in the corrosion products of the Al–Zn coating allows dissolution,but,at the same time,Zn_5（OH）_6（CO_3）_2and Zn_6Al_2（OH）_（16）CO_3are formed and act to reduce the corrosion rate.

关键词： Self-healing coating Corrosion Arc thermal spray Electrochemical impedance spectroscopy