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Recent research progress on magnesium alloys in Korea:A review

Journal of Magnesium and Alloys 2023年第10期11卷 3545-3584页

作者： Sung hyuk park Ye Jin Kim Hyun Ji Kim Sang-Cheol Jin Jong Un Lee Alexander Komissarov Kwang Seon Shin School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Laboratory of Hybrid Nanostructured Materials National University of Science and TechnologyMoscow 119049Russia Laboratory of Medical Bioresorption and Bioresistance Moscow State University of Medicine and DentistryMoscow 127473Russia Magnesium Technology Innovation Center School of Materials Science and EngineeringSeoul National UniversitySeoul 08826Republic of Korea

This review highlights the recent advancements in Mg research in South Korea with a prime focus on high-speed-extrudable Mg–Bi-based alloys for high productivity and strength, innovative techniques utilizing {10–12} twinning for improved mechanical properties, and alloying and processing methods for enhanced corrosion resistance. High-alloyed Mg–Bi-based alloys possess thermally stable α-Mg matrix and secondary phase, which ensures high-speed extrusion of these alloys at elevated temperatures without hot cracking. Consequently, they exhibit outstanding extrudability with a maximum extrusion speed of up to 70 m/min. Furthermore, their high alloying contents offer excellent strength even after high-speed extrusion through strong solid solution hardening and particle hardening effects, making them suitable for high-performance extruded Mg products. The pre-twinning process utilizing {10–12} twinning and the combined process of pre-twinning and subsequent annealing have shown promise in controlling microstructure and texture of wrought Mg alloys and thus enhancing their mechanical properties. The pre-twinning process enhances tensile strength, fatigue properties, and age-hardening rate of Mg alloys. Furthermore, the combined processes of pre-twinning and subsequent annealing considerably improve their ductility, stretch formability, bending formability,and damping capacity. Efforts have been made to improve the corrosion resistance of Mg alloys through alloying additions, process treatments,and surface coatings. Alloying elements like Ca, Sc, and Sm alter the microstructural features(such as secondary phases and grain size)that affect the corrosion phenomenon. Process treatments such as multidirectional forging, screw rolling, and pulse electron beam can also improve the corrosion resistance by refining the microstructure. Furthermore, advanced surface coating technologies can create durable and corrosion-resistant layers for effectively protecting the Mg alloys. All th

关键词： South Korea Mg–Bi alloys {10–12}twinning Corrosion Mechanical properties

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Designing a Biomimetic Ornithopter Capable of Sustained and Controlled Flight

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Journal of Bionic Engineering 2008年第1期5卷 39-47页

作者： Joon hyuk park Kwang-Joon Yoon Department of Aerospace Information System and Artificial Muscle Research Center Konkuk University Seoul 143-701 Korea

We describe the design of four ornithopters ranging in wing span from 10 cm to 40 cm, and in weight from 5 g to 45 g. The controllability and power supply are two major considerations, so we compare the efficiency and characteristics between different types of subsystems such as gearbox and tail shape. Our current omithopter is radio-controlled with inbuilt visual sensing and capable of takeoff and landing. We also concentrate on its wing efficiency based on design inspired by a real insect wing and consider that aspects of insect flight such as delayed stall and wake capture are essential at such small size. Most importantly, the advance ratio, controlled either by enlarging the wing beat amplitude or raising the wing beat frequency, is the most significant factor in an ornithopter which mimics an insect.

关键词： biomimetic ornithopter flapping wing unsteady state low Reynolds number

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Journal of Central South University 2013年第8期20卷 2233-2238页

作者： park Jean-Ho HWANG Jai-hyuk park Wook-Je 魏荷 LEE Sang-hyuk Advanced Convergent Technology R&D Group Korea Institute of Industrial Technology School of Aerospace & Mechanical Engineering Korea Aerospace University Institute for Information and Electronics Research Inha University Department of Electrical and Electronic Engineering Xi'an Jiaotong-Liverpool University

Study of fuzzy entropy and similarity measure on intuitionistic fuzzy sets (IFSs) was proposed and analyzed. Unlike fuzzy set, IFSs contain uncertainty named hesitance, which is contained in fuzzy membership function itself. Hence, designing fuzzy entropy is not easy because of many entropy definitions. By considering different fuzzy entropy definitions, fuzzy entropy on IFSs is designed and discussed. Similarity measure was also presented and its usefulness was verified to evaluate degree of similarity.

关键词：直觉模糊集相似度量相似性度量模糊隶属函数模糊熵不确定性相似程度有用性

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Influence of Bi addition on dynamic recrystallization and precipitation behaviors during hot extrusion of pure Mg

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Journal of Materials Science & Technology 2020年第9期44卷 62-75页

作者： Jongbin Go Jong Un Lee Hui Yu Sung hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea School of Materials Science and Engineering Hebei University of TechnologyTianjin300130China

Low material cost and high extrudability for ensuring price competitiveness with Al alloys,as well as excellent mechanical properties,are essential for expanding the application range of Mg *** is a promising alloying element for developing extruded Mg alloys that satisfy such *** is inexpensive,exhibits a high solubility limit,and forms a thermally stable Mg3Bi2 phase,which improves the commercial viability and enables the high-speed extrusion of Mg–Bi *** this study,the effects of Bi addition on the dynamic recrystallization(DRX)and dynamic precipitation behaviors during hot extrusion of a pure Mg and the resultant microstructure and mechanical properties of the extruded materials were *** addition of 6 wt%and 9 wt%Bi to a pure Mg yielded numerous fine Mg3Bi2 precipitates during the early stage of hot ***,the area fraction of dynamic recrystallized(DRXed)grains decreased because of DRX-behavior suppression by the Zener pinning ***,the DRXed grain size was substantially reduced through the grain-boundary pinning *** size and number of undissolved Mg3Bi2 particles in the homogenized billets increased when the Bi content was increased,which resulted in increased DRX fractions owing to the enhanced levels of particle stimulated *** addition yielded considerable strength improvement of the extruded pure ***,the extruded Mg–Bi binary materials were less ductile than the extruded pure Mg *** lower ductility resulted from the cracking at twins formed in the coarse unDRXed grains of the Mg-6Bi material and the cracking at large undissolved Mg3Bi2 particles in the Mg-9Bi material.

关键词： Magnesium Bi addition Extrusion Recrystallization Precipitation

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OTS Scheme Based Secure Architecture for Energy-Efficient IoT in Edge Infrastructure

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Computers, Materials & Continua 2021年第3期66卷 2905-2922页

作者： Sushil Kumar Singh Yi Pan Jong hyuk park Department of Computer Science and Engineering Seoul National University of Science and TechnologySeoul01811South Korea Department of Computer Science Georgia State UniversityAtlantaGA30302-5060USA

For the past few decades,the Internet of Things(IoT)has been one of the main pillars wielding significant impact on various advanced industrial applications,including smart energy,smart manufacturing,and *** applications are related to industrial plants,automation,and e-healthcare *** applications have several issues related to developing,planning,and managing the ***,IoT is transforming into G-IoT(Green Internet of Things),which realizes energy *** provides high power efficiency,enhances communication and ***,this paradigm did not resolve all smart applications’challenges in edge infrastructure,such as communication bandwidth,centralization,security,and *** this paper,we propose the OTS Scheme based Secure Architecture for Energy-Efficient IoT in Edge Infrastructure to resolve these *** OTS-based Blockchain-enabled distributed network is used at the fog layer for security and *** evaluated our proposed architecture’s performance quantitatively as well as security and *** conducted a comparative analysis with existing studies with different measures,including computing cost time and communication *** a result of the evaluation,our proposed architecture showed better performance.

关键词： Blockchain energy-efficient IoT ots scheme edge infrastructure security and privacy

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Probing temperature-dependent interlayer coupling in a MoS2/h-BN heterostructure

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Nano Research 2020年第2期13卷 576-582页

作者： Hamin park Gwang hyuk Shin Khang June Lee Sung-Yool Choi School of Electrical Engineering Centerfor Advanced Materials Discovery towards 3D Display KAISTDaejeon 34141Republic of Korea

Stacking of atomically thin layers of two-dimensional materials has revealed extraordinary physical phenomena owing to van der Waals(vdW)interaction at the ***,most of the studies focused on the transition metal dichalcogenide(TMD)/TMD heterostructure,while the interlayer coupling of the TMD/hexagonal boron nitride(h-BN)heterostructure has not been extensively explored despite its *** this study,the temperature-dependent interlayer coupling is demonstrated in a heterostructure of molybdenum disulfide(MoS2)and *** interface between MoS2 and the insulating substrate exerts a significant spectroscopic impact on MoS2 through substrate-induced local strain,charged impurity,and vdW *** non-resonant conditions,temperature-dependent peak shifts in Raman and photoluminescence(PL)spectra of MoS2 reveal the evolution of interlayer *** frequencies and PL peak energies at different temperatures demonstrate how substrate-induced strain,impurity,and vdW interactions at the interface influence phonon vibration and excitonic transition of *** resonant conditions at low temperature,anomalous Raman modes appear in the MoS2/h-BN heterostructure because of the enhanced electron-phonon coupling and vdW *** anomalous Raman modes are quantitatively investigated by the deconvolution of the resonance Raman spectra and described by interlayer coupling at low temperature,in agreement with complementary indications from the temperature-dependent evolution of non-resonant Raman and PL spectra.

关键词： van der Waals heterostructures interlayer coupling Raman spectroscopy excitonic resonance photoluminescence

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Microstructural characteristics of AZ31 alloys rolled at room and cryogenic temperatures and their variation during annealing

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Journal of Magnesium and Alloys 2020年第2期8卷 537-545页

作者： Sang Won Lee Sang-Hoon Kim Sung hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigates the microstructural characteristics of AZ31 Mg alloys rolled at room temperature(RT)and cryogenic temperature(CT)and the variation in their microstructure and hardness during subsequent *** induces the formation of more side cracks than does RT rolling,because of the reduction in the ability of the material to accommodate deformation at ***{10-11}contraction and{10-11}-{10-12}double twins are formed in both the material rolled at RT and that rolled at CT,because the grains of the initial material are favorably oriented for{10-11}twinning under *** RT-rolled material has a higher dislocation density than the cryorolled material,and more twins are uniformly distributed throughout the former *** a result,static recrystallization during subsequent annealing is more pronounced in the RT-rolled material,which results in the formation of a highly recrystallized homogeneous microstructure after *** contrast,the formed twins are predominantly present along the shear bands in the cryorolled material,as a result of which this material has an inhomogeneous bi modal structure containing a large amount of coarse unrecrystallized grains after *** hardness of the annealed RT-rolled material is higher than that of the annealed cryorolled material owing to the finer grain structure of the former.

关键词： Magnesium Rolling Cryogenic temperature Annealing Microstructure

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Effects of initial texture on deformation behavior during cold rolling and static recrystallization during subsequent annealing of AZ31 alloy

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Journal of Materials Science & Technology 2021年第7期66卷 139-149页

作者： Sang Won Lee Gukin Han Tea-Sung Jun Sung hyuk park School of Materials Science and Engineering.Kyungpook National University Daegu 41566Republic of Korea Department of Mechanical Engineering Incheon National UniversityIncheon 22012Republic of Korea

This study demonstrates that the initial texture of Mg alloy significantly affects the microstructure developed during cold rolling and the recrystallization behavior during subsequent annealing. In a sample with a texture oriented toward the normal direction(ND sample), thick and large-sized shear bands are intensively formed during cold rolling and the deformation is strongly localized along these bands. In contrast,in a sample with a texture oriented toward the transverse direction(TD sample), many {10-12} twins are formed at the early stage of cold rolling, and then, numerous small-sized shear bands are formed in these twins. Results of nanoindentation tests reveal that the cold-rolled ND sample has internal strain energy that is substantially concentrated along the shear bands, whereas the cold-rolled TD sample has a large amount of internal strain energy that is homogeneously distributed throughout the material;this latter behavior is strongly related to the extensive {10-12} twinning and the resultant microstructural variations in the TD sample. During subsequent annealing, recrystallization occurs locally along the shear bands in the ND sample, which leads to the formation of a bimodal grain structure comprising fine recrystallized grains and coarse unrecrystallized grains. In contrast, during subsequent annealing of the TD sample, static recrystallization occurs homogeneously throughout the material, which results in the formation of a uniform grain structure that mostly comprises equiaxed recrystallized grains.

关键词： Magnesium alloy Cold rolling Initial texture Twinning Static recrystallization

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Indigenous microbiota protects development of medication-related osteonecrosis induced by periapical disease in mice

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International Journal of Oral Science 2022年第2期14卷 156-163页

作者： Wen Du Mengyu Yang Terresa Kim Sol Kim Drake W.Williams Maryam Esmaeili Christine Hong Ki-hyuk Shin Mo K.Kang No-Hee park Reuben H.Kim State Key Laboratory of Oral Diseases&National Clinical Research Center for Oral Diseases&Department of Prosthodontics West China Hospital of StomatologySichuan UniversityChengduChina The Shapiro Family Laboratory of Viral Oncology and Aging Research Los AngelesUSA Section of Restorative Dentistry UCLA School of DentistryLos AngelesUSA Department of Orofacial Sciences UCSF School of DentistrySan FranciscoUSA UCLA Jonsson Comprehensive Cancer Center Los AngelesUSA David Geffen School of Medicine at UCLA Los AngelesUSA

Bacterial infection is a common finding in patients,who develop medication-related osteonecrosis of the jaw(MRONJ)by the longterm and/or high-dose use of anti-resorptive agents such as bisphosphonate(BPs).However,pathological role of bacteria in MRONJ development at the early stage remains ***,we demonstrated that commensal microbiota protects against MRONJ development in the pulp-exposed periapical periodontitis mouse model.C57/BL6 female mice were treated with intragastric broadspectrum antibiotics for 1 *** acid(ZOL)through intravenous injection and antibiotics in drinking water were administered for throughout the *** was exposed on the left maxillary first molar,then the mice were left for 5 weeks after which bilateral maxillary first molar was extracted and mice were left for additional 3 weeks to *** mice were harvested,and cecum,maxilla,and femurs were *** development was assessed usingμCT and histologic *** antibiotic was treated in mice,these mice had no weight changes,but developed significantly enlarged ceca compared to the control group(CTL mice).Periapical bone resorption prior to the tooth extraction was similarly prevented when treated with antibiotics,which was confirmed by decreased osteoclasts and *** treatment with pulp exposure significantly increased bone necrosis as determined by empty lacunae and necrotic bone ***,antibiotics treatment could further exacerbate bone necrosis,with increased osteoclast *** findings suggest that the commensal microbiome may play protective role,rather than pathological role,in the early stages of MRONJ development.

关键词： protective finding antibiotics

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Journal of Central South University 2012年第4期19卷 1032-1039页

作者： park Wook-je LEE Sang-min LEE Sang-hyuk Institute for Information and Electronics Research Inha University Department of Electrical and Electronic Engineering Xi'an Jiaotong-Liverpool University

Similarity measure construction has been proposed as fault detection of flight test method in order to obtain the primary control surface stuck and the combination stuck of primary *** measures were obtained through analyzing the certainty and uncertainty of fuzzy membership functions,which were designed based on well-known Hamming *** was applied to the fault detection of primary control surface stuck of uninhabited aerial vehicle(UAV).At post-failure control surface,if the UAV is controllable and trimmable using other control surfaces,the UAV is able to fly or return to the safety region through reconfiguration of flight control *** detect the fault,similarity measure computations were carried *** result could be applicable with the real-time parameter estimation *** monitoring the value of coefficients due to the control surface deviation,it becomes aware that the control surface fault occurs or *** control surface stuck position and value were separated by comparing the trim value with the reference *** is the advantage of increasing in reliability without adding sensors or with additional low cost.

关键词：相似性度量测量距离飞行试验设计故障检测应用模糊隶属函数飞行控制系统

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