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Very High Cycle Fatigue Behaviors and Surface Crack Growth Mechanism of Hydrogen-Embrittled AISI 304 Stainless Steels

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Materials Sciences and Applications 2018年第4期9卷 393-411页

作者： seung-Hoon Nahm Hyun-Bo Shim Un-Bong baek Chang-Min Suh Korea Research Institute of Standards and Science Daejeon Republic of Korea School of Mechanical Engineering Yeungnam University Daegu Republic of Korea School of Mechanical Engineering Kyungpook Nat’l University Daegu Republic of Korea

The influence of hydrogen embrittlement on the fatigue behaviors of AISI 304 stainless steel is investigated. The fatigue endurance limits of the untreated and hydrogen-embrittled materials were almost the same at 400 MPa, and hydrogen embrittlement had little influence even though the sample contained about 8.1 times more hydrogen. Thus, the sensitivity of hydrogen gas in this material is very low. A surface crack initiation, growth, coalescence, and micro ridge model is proposed in this study. Slip line formation?⇒microcrack formation?⇒increases in the crack width, and blunting of the crack tip as it grows?⇒formation of many slip lines because of deformation in the shear direction?⇒growth of the crack in the shear direction, forming micro ridges, coalescence with adjacent cracks ⇒?continuous initiation, growth, coalescence, and ridge formation of surface cracks and specimen breakage.

关键词： Hydrogen-Embrittled Fatigue Behaviors Surface Crack Initiation Growth Coalescence Micro Ridge Formation VHCF (Very High Cycle Fatigue) Fracture Surface Analysis

Network Traffic Obfuscation System for IIoT-Cloud Control Systems

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Computers, Materials & Continua 2022年第9期72卷 4911-4929页

作者： Yangjae Lee Sung Hoon baek Jung Taek Seo Ki-Woong Park SysCore Lab. Sejong UniversitySeoul05006Korea Department of Computer System Engineering Jungwon UniversityChungcheongbuk-do28024Korea Department of Computer Engineering Gachon UniversityGyeonggi-do13120Korea

One of the latest technologies enabling remote control,operational efficiency upgrades,and real-time big-data monitoring in an industrial control system(ICS)is the IIoT-Cloud ICS,which integrates the Industrial Internet of Things(IIoT)and the cloud into the *** an ICS benefits from the application of IIoT and the cloud in terms of cost reduction,efficiency improvement,and real-time monitoring,the application of this technology to an ICS poses an unprecedented security risk by exposing its terminal devices to the outside *** adversary can collect information regarding senders,recipients,and prime-time slots through traffic analysis and use it as a linchpin for the next attack,posing a potential threat to the *** address this problem,we designed a network traffic obfuscation system(NTOS)for the IIoT-Cloud ICS,based on the requirements derived from the ICS characteristics and limitations of existing NTOS *** a strategy to solve this problem wherein a decrease in the traffic volume facilitates traffic analysis or reduces the packet transmission speed,we proposed an NTOS based on packet scrambling,wherein a packet is split into multiple pieces before transmission,thus obfuscating network *** minimize the ICS modification and downtime,the proposed NTOS was designed using an agentbased *** addition,for the ICS network traffic analyzer to operate normally in an environment wherein the NTOS is applied,a rule-based NTOS was adopted such that the actual traffic flow is known only to the device that is aware of the rule and is blocked for *** experimental results verified that the same time requested for response and level of difficulty of analysis were maintained by the application of an NTOS based on packet scrambling,even when the number of requests received by the server per second was *** network traffic analyzer of the ICS can capture the packet flow by using the pre-communicated NTOS *** addition,by designing an N

关键词： Cloud computing system moving-target defense container orchestration

Survival analysis following early surgical success in intermittent exotropia surgery

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International Journal of Ophthalmology(English edition) 2014年第3期7卷 528-533页

作者： Joo Yeon Lee Sung Ju Ko Sung Uk baek Department of Ophthalmology Hallym University College of Medicine

AIM:To assess the consecutive recurrence following early success of intermittent exotropia surgery and to determine the clinical factors that affect the ***:One hundred and thirty-five patients who underwent intermittent exotropia surgery and experienced early surgical success[≤5 prism diopters(PD)esophoria(E)to≤10 PD exophoria(X)on the postoperative sixth month]were enrolled in this *** consecutive survival on the postoperative first year,second year and third year and at the last visit of fourth year or more,and the factors that might affect their survival,were *** final surgical outcomes after the postoperative fourth year were also investigated by dividing the patients into the success group(≤5 PD E to≤10 PD X)and the failure group(>5 PD esodeviation or>10 PD exodeviation)RESULTS:The survival rates from the Kaplan-Meier analysis were 97.78%,92.89%,83.70%and 50.49%on the postoperative first,second and third years and fourth year or more,*** of the clinical factors was determined to have affected the *** amount of the exodrift was largest(2.29 PD)between the first year and the second year,and smallest(1.47 PD)between the fourth year and the last ***-three patients had their final visit after the postoperative fourth year,and 29 of them were in the failure *** patients in the failure group had an intermittent exotropia(IXT)of<20 PD with good to fair distant fusion;two had an IXT of<20 PD with poor distant fusion;one had an IXT of≥20 PD with fair distant fusion;and another had delayed-onset consecutive *** exodeviation on the postoperative sixth month was smaller in the success group than in the failure group(2.81 PD vs 5.86 PD,P=0.012).The reoperation rate for recurrent IXT was 3.7%.CONCLUSION:The survival rate steadily decreases with the exodrift,but the amount of the exodrift decreases with long-term *** final outcomes demonstrate favorable results via surgic

关键词： long-term outcome survival analysis intermittent exotropia surgery

Work up for the clopidogrel hypersensitivity that led to recognising the undi- agnosed myelodysplastic syndrome

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Journal of Geriatric Cardiology 2016年第3期13卷 274-276页

作者： Yoo Sang baek Jung Woo Lee Jiehyun Jeon Department of Dermatology College of Medicine Korea University Seoul South Korea

Antiplatelet therapy with clopidogrel is widely used as a preventive strategy in patients with acute coronary syn- drome, particularly after stent *** mani- festations of clopidogrel hypersensitivity reaction have been reported including cutaneous,and hematologic symp- toms[31 as well as fatal reactions including thrombotic throm- bocytopenic purpura （TTP）.

关键词： Clopidogrel Hypersensitivity Myelodysplastic syndrome

Analytical Study on Piezoelectric Effects on Exciton Dissociation

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Communications in Computational Physics 2016年第6期20卷 179-187页

作者： SeongMin Kim Jaewook Ha Hyeok Kim Jin-baek Kim The Office of the Theory&Modeling Based Design of Energy Harvesting(private lab) Maetan 3-dongYeongtong-guSuwon-siGyeonggi-do 443-373Korea Department of Chemistry Korea Advanced Institute of Science and TechnologyDaejeon 305-701Korea Photo-Electronic Hybrids Research Center Korea Institute of Science and TechnologySeoul 136-791Korea CAE Platform Technology LabSamsung Advanced Institute of Technology

We analytically and numerically compute the Onsager dissociation rate(exciton dissociation)on an interface induced by a piezoelectric potential in an inorganicorganic hybrid p-n junction system(ZnO+(poly(p-phenylene vinylene));PPV).When a positive piezoelectric potential is created at the interface region owing to the deformation of the system,free electrons accumulate at the ***,screening effects are *** is assumed that the electron layer formed at the interface then attracts free holes from the p-type PPV region,which leads to exciton formation,possibly via the Langevin recombination *** increased exciton density can then contribute to the Onsager dissociation rate,which is maximum around the *** paper focuses on the role of piezoelectric effects in promoting exciton formation at the interface and its relation with the exciton dissociation rate.

关键词： Exciton dissociation Onsager rate piezoelectric p-n junction recombination

Virtual Mold Technique in Thermal Stress Analysis during Casting Process

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Journal of Materials Science & Technology 2008年第3期24卷 359-363页

作者： Si-Young Kwak Jae-Wook baek Jeong-Ho Nam Jeong-Kil Choi E-Design Center Korea Institute of Industrial Technology Department of Virtual Engineering Korea University of Science & Technology

It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.

关键词： Casting process Thermal stress analysis Virtual mold

Enhancing the efficiency and scalability of perovskite solar cells through pseudo-halide salt addition

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Journal of Materials Science & Technology 2023年第34期165卷 161-169页

作者： Dohun baek Geon Yeong Park Jeongbeom Cha Hyemi Na Dong Seok Ham Min Kim School of Chemical Engineering Future Energy Research CenterJeonbuk National UniversityJeonju 54896Republic of Korea Graduate School of Integrated Energy-AI Jeonbuk National UniversityJeonju 54896Republic of Korea Chemical Materials Solutions Center Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea

Organic-inorganic halide perovskites have significant potential for application in next-generation solar ***,their applications are limited by challenges associated with large-area processability and long-term stability owing to the presence of pinholes and defect ***,we incorporated cesium formate in a perovskite active layer using a sequential perovskite fabrication process to eliminate the defect sites of perovskites and improve the film processability via roll-to-roll(R2R)*** addition of cesium formate salt to the PbI2 layer influences the perovskite crystal formation behavior as well as increases the perovskite crystallinity and decreases the defect ***,cesium formate addition eliminated small PbI2 grains and smoothed the perovskite surface,resulting in a large crystal grain *** formate ions interact with the PbI2 component and passivate halide vacancy defects,reducing nonradiative recombination and improving charge ***,the treated perovskite films were highly stable in air,exhibiting improved efficiency retention over time and achieving a power conversion efficiency(PCE)of>22%compared to the ***,the additive-treated perovskite film was processed using the R2R method,achieving a high PCE of>14%with minimal hysteresis.

关键词： Perovskite Solar Cells Pseudo-halide ion Stability Roll-to-roll process

Memristive Devices Based on Two-Dimensional Transition Metal Chalcogenides for Neuromorphic Computing

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Nano-Micro Letters 2022年第4期14卷 29-58页

作者： Ki Chang Kwon Ji Hyun baek Kootak Hong Soo Young Kim Ho Won Jang Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Republic of Korea Interdisciplinary Materials Measurement Institute Korea Research Institute of Standards and Science(KRISS)Daejeon 34133Republic of Korea Department of Materials Science and Engineering Institute of Green Manufacturing TechnologyKorea UniversitySeoul 02841Republic of Korea Advanced Institute of Convergence Technology Seoul National UniversitySuwon 16229Korea

Two-dimensional(2D)transition metal chalcogenides(TMC)and their heterostructures are appealing as building blocks in a wide range of electronic and optoelectronic devices,particularly futuristic memristive and synaptic devices for brain-inspired neuromorphic computing *** distinct properties such as high durability,electrical and optical tunability,clean surface,flexibility,and LEGO-staking capability enable simple fabrication with high integration density,energy-efficient operation,and high *** review provides a thorough examination of high-performance memristors based on 2D TMCs for neuromorphic computing applications,including the promise of 2D TMC materials and heterostructures,as well as the state-of-the-art demonstration of memristive *** challenges and future prospects for the development of these emerging materials and devices are also *** purpose of this review is to provide an outlook on the fabrication and characterization of neuromorphic memristors based on 2D TMCs.

关键词： Two-dimensional materials Memristors Neuromorphic computing Artificial synapses Transition metal chalcogenides

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采用轻压下技术减少板坯中心偏析

钢铁 2004年第Z1期39卷 286-288页

作者： Jemin Park Hong-gu Ryu seung-kwan baek Shin-Eon Kang Steel Making Department Gwangyang Works POSCO Steel Making Department Gwangyang Works POSCO Steel Making Department Gwangyang Works POSCO POSCO Research Laboratory

近来,为提高竞争力,提高API钢市场占有率,必须增加高质量API钢的产量,尽最大努力去满足消费者对产品质量的严格要求,尤其是生产耐酸钢.不仅要最大限度地控制钢中残留元素和夹杂物的含量,而且还要避免中心偏析.因此,POSCO正致力于开发生... 详细信息

近来,为提高竞争力,提高API钢市场占有率,必须增加高质量API钢的产量,尽最大努力去满足消费者对产品质量的严格要求,尤其是生产耐酸钢.不仅要最大限度地控制钢中残留元素和夹杂物的含量,而且还要避免中心偏析.因此,POSCO正致力于开发生产工艺,更新基础设备,以满足消费者的要求.在POSCO的Gwangyang工厂,由于受铸机条件限制,控制板坯中心偏析有一定难度.为了克服这一困难,Gwangyang工厂在1-3铸机上安装了动态轻压下设备.动态轻压下系统的操作条件处于优化阶段.轻压下设备上采用了动态二次冷却系统和热示踪模型,板坯中心偏析系数有了明显降低.

关键词：连铸轻压下二次冷却中心偏析