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Robust vision-based displacement measurement and acceleration estimation using RANSAC and Kalman filter

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Earthquake Engineering and Engineering Vibration 2023年第2期22卷 347-358页

作者： jongbin Won jong-Woong Park Min-hyuk Song Youn-Sik Kim Dosoo Moon Department of Civil and Environmental Engineering Chung-Ang UniversityDongjakSeoul 06974Korea Department of Smart Cities Chung-Ang UniversityDongjakSeoul 06974Korea R&D Division Tantan Safety co.LtdSeongdongSeoul 04798Korea Department of Civil and Environmental Engineering University of Hawaii at ManoaHonolulu 96822USA

Computer vision(CV)-based techniques have been widely used in the field of structural health monitoring(SHM)owing to ease of installation and cost-effectiveness for displacement *** paper introduces computer vision based method for robust displacement measurement under occlusion by incorporating random sample consensus(RANSAC).The proposed method uses the Kanade-Lucas-Tomasi(KLT)tracker to extract feature points for tracking,and these feature points are filtered through RANSAC to remove points that are noisy or *** the filtered feature points,the proposed method incorporates Kalman filter to estimate acceleration from velocity and displacement extracted by the *** validation,numerical simulation and experimental validation are *** the simulation,performance of the proposed RANSAC filtering was validated to extract correct displacement out of group of displacements that includes dummy displacement with noise or *** the experiment,both RANSAC filtering and acceleration measurement were validated by partially occluding the target for tracking attached on the *** results demonstrated that the proposed method successfully measures displacement and estimates acceleration as compared to a reference displacement sensor and accelerometer,even under occluded conditions.

关键词： computer vision structural displacement structural acceleration RANSAC Kalman filter

Effects of Sn addition on the microstructure and mechanical properties of extruded Mg-Bi binary alloy

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Journal of Magnesium and Alloys 2022年第3期10卷 920-931页

作者： Sang-Cheol Jin jong Un Lee jongbin Go Hui Yu Sung hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566South Korea Department of Materials Science and Engineering Kyoto UniversityYoshida-honmachiSakyo-kuKyoto606-8501Japan School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China

We investigated the effects of Sn addition on the microstructural characteristics and mechanical properties of an extruded Mg-Bi binary alloy by comparing Mg-5 Bi(B5)and Mg-5 Bi-4 Sn(BT54).Both the extruded alloys exhibit a partially recrystallized grain structure with a strong extrusion fiber texture and numerous Mg3Bi2 ***,the addition of Sn significantly decreases the average grain size of the extruded alloy from 123.9 to 75.2μ*** Sn solute atoms inhibit the activity of dislocation slip,which reduces the internal strain energy accumulated in the dynamically recrystallized(DRXed)grains during ***,this reduced strain energy leads to the decrease in the DRXed grain size owing to weakened grain growth during natural *** extruded BT54 alloy exhibits higher tensile strength and ductility than the extruded B5 *** improvement in the strength by the Sn addition is attributed to the combined effects of grain refinement,Sn solute atoms,and increased dislocation *** formation of{10-11}and{10-11}-{10-12}twins during tension is suppressed by the grain refinement,thereby improving the tensile elongation considerably.

关键词： Mg±Bi alloy Extrusion Dynamic recrystallization Microstructure Mechanical properties.

Knot impingement after arthroscopic rotator cuff repair mimicking infection:A case report

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World Journal of Clinical Cases 2022年第15期10卷 5097-5102页

作者： Du-Han Kim jong-hyuk Jeon Byung-Chan Choi Chul-Hyun Cho Department of Orthopedic Surgery Keimyung University Dongsan HospitalKeimyung University School of MedicineDaegu 42601South Korea

BACKGROUND Knot impingement as a complication after arthroscopic rotator cuff repair(ARCR)has been suggested as a cause of persistent pain with limited *** report on a case involving a patient who developed knot impingement after ARCR who complained of acute onset of pain with limited motion,which was confused with *** SUMMARY A 55-year-old female who complained of severe pain with limited motion of the right shoulder visited our emergency *** range of motion could not be evaluated due to the patient’s severe *** patient had undergone ARCR using a suture-bridge technique at a local clinic four months ago for treatment of a small supraspinatus tear of the right *** erosive change of the undersurface of the acromion was observed on plain radiographs of the right shoulder,and a moderate amount of bursal fluid and synovial thickening with enhancement was observed by magnetic resonance *** of an analysis of the aspirated fluid showed that the WBC count was 3960 with 90% *** arthroscopic view showed healing of the repaired supraspinatus tendon and loose suture threads and knots with severe subacromial bursitis were *** of inflammatory tissues of the glenohumeral joint and subacromial space was performed for the removal of all suture *** patient’s symptoms subsided immediately after the surgical *** Although the incidence of knot impingement is rare,the possibility of knot impingement after ARCR should be a consideration.

关键词： Rotator cuff Knot impingement Shoulder Infection Arthroscopy Case report

Variations in microstructure and bending formability of extruded Mg–Al–Zn–Ca–Y–MM alloy with precompression and subsequent annealing treatment conditions

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Journal of Magnesium and Alloys 2022年第9期10卷 2475-2490页

作者： jong Un Lee Sang-Hoon Kim Dong Hee Lee Hyun Ji Kim Young Min Kim Sung hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Agency for Defense Development Daejeon 34186Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

In this study, the bending formability of an extruded Mg–9Al–1Zn–0.3Mn–0.9Ca–0.6Y–0.5 MM(AZXWMM91100, wt%) alloy at room temperature is significantly improved through application of a combined precompression and subsequent annealing(PCA) treatment. As the amount of precompression applied along the extrusion direction(ED)(i.e., the total strain) increases from 4% to 6%, the area fraction of ED-oriented grains of the PCA-treated alloy increases, which consequently causes an improvement in its bending formability because these grains accommodate larger tensile strain along the ED during bending. As the temperature of the subsequent annealing treatment increases from 350 ℃ to 450 ℃, both the area fraction of the ED-oriented grains and the average grain size increase, and the residual dislocation density decreases owing to the promotion of boundary migration and occurrence of the recovery process at higher ***, the bending formability of both the 4%-precompressed and the 6%-precompressed samples increases with an increase in the annealing temperature. However, when the precompressed samples are annealed at 300 ℃, their bending formability is lower than that of the extruded alloy because the dislocations formed by precompression remain even after the subsequent annealing at this temperature.

关键词： Magnesium Extrusion Bending Formability Texture

Role of multidetector computed tomography in patients with acute infectious colitis

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World Journal of Clinical Cases 2022年第12期10卷 3686-3697页

作者： Seung Jung Yu Jae hyuk Heo Eun Jeong Choi jong hyuk Kim Hong Sub Lee Sun Young Kim Jae Hoon Lim Department of Internal Medicine Inje University Busan Paik HospitalBusan 47392South Korea Department of Radiology Myongji HospitalHanyang University College of MedicineGoyang 10475South Korea Department of Cancer Control and Population Health National Cancer CenterGoyang 10408South Korea

BACKGROUND The role of multidetector computed tomography(MDCT)in patients with acute infectious colitis is still *** To examine the usefulness of MDCT in distinguishing the etiology of acute infectious *** Overall,244 patients who met the criteria for acute infectious colitis and visited the Hospital from February 2015 to 2018 were retrospectively enrolled and divided into two groups(bacterial:204,viral:40)according to causes of acute colitis,based on stool *** MDCT parameters,including wall thickening,submucosal edema,mucosal enhancement,serosa involvement,empty colon sign,small bowel involvement,comb sign,continuous distribution,accordion sign,mucosal thickening,and lymph node enlargement,were constructed in a blinded *** MDCT parameters of wall thickening(OR:13.60;95%CI:5.80–31.88;P<0.001),submucosal edema(OR:36.08;95%CI:13.54–96.13;P<0.001),mucosal enhancement(OR:22.55;95%CI:9.28–54.81;P<0.001),serosal involvement(OR:14.50;95%CI:3.33–63.23;P<0.001),empty colon sign(OR:6.68;95%CI: 2.44–18.32;P < 0.001), continuous distribution (OR: 24.09;95%CI: 9.38–61.90;P < 0.001), accordionsign (OR: 9.02;95%CI: 1.12–72.35;P = 0.038), mucosal thickening (OR: 46.41;95%CI: 10.38–207.51;P< 0.001), and lymph node enlargement (OR: 4.39;95%CI: 1.22–15.72;P = 0.023) were significantlyassociated with bacterial colitis. At least one positive finding in four CT outcomes (submucosaledema, mucosal enhancement, continuous distribution, mucosal thickening) in summer showed ahigh probability of bacterial colitis (sensitivity, 41.67;specificity, 92.50;OR: 24.95).CONCLUSIONMDCT provides many clues that can be useful in suggesting a specific etiology of acute infectiouscolitis.

关键词： Colitis Multidetector computed tomography Differential diagnosis Bacterial infections Viral infections

Recent research progress on magnesium alloys in Korea:A review

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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

Accelerated precipitation behavior of cast Mg-Al-Zn alloy by grain refinement

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Journal of Materials Science & Technology 2018年第2期34卷 265-276页

作者： Sang-Hoon Kim jong Un Lee Ye Jin Kim Jun Ho Bae bong Sun You Sung hyuk Park School of Materials Science and Engineering Kyungpook National University Implementation Research Division Korea Institute of Materials Science

This study demonstrates that the precipitation behavior of 13-Mg17Al12 phase during aging and the resultant variation in hardness and mechanical properties of cast Mg-Al-Zn alloy are strongly dependent on initial grain size. Grain size reduction accelerates discontinuous precipitation at the early stage of aging treatment by increasing the area fraction of grain boundaries that can act as nucleation sites for discontinuous precipitates （DP）, but it does not influence DP growth rate. Grain refinement also prematurely terminates continuous precipitation because the formation of a large number of DP reduces the amount of AI dissolved in the matrix, which is required for the formation of continuous precipitates （CP）. This promotion of DP formation and early termination of CP formation significantly decrease the peak-aging time to one-third. The enhanced precipitation behavior also leads to an additional hardness improvement in the aged alloy, along with an increase in hardness owing to grain boundary strengthening by grain refinement. The amount of increase in hardness changes with aging time, which is determined by the variation of three variables with aging time： DP fraction difference between refined and nonrefined alloys, hardness difference between DP and matrix, and matrix hardness difference between the two alloys. Grain refinement improves both tensile strength and ductility of the homogenized alloy owing to grain boundary strengthening and suppression of twinning activation, respectively. However, the loss of ductility after peak-aging treatment is greater in the refined alloy because of the larger amount of DP acting as a crack source in this alloy.

关键词： Magnesium Grain refinement Aging Precipitation Tensile properties

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

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