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Highly Flexible Fabrics/Epoxy Composites with Hybrid Carbon Nanofillers for Absorption-Dominated Electromagnetic Interference Shielding

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Nano-Micro Letters 2022年第11期14卷 307-323页

作者： Jong-hoon Lee Yoon-Sub Kim Hea-Jin Ru Seul-Yi Lee Soo-Jin park Department of Chemistry Inha University100 InharoIncheon 22212Korea Korea Architecture Safety Testing and Research Institute(KASTI) 88 Gasan Digital 1-roSeoul 08590Korea

Epoxy-based nano-composites can be ideal electromagnetic interference(EMI)-shielding materials owing to their lightness,chemical inertness,and mechanical durability.However,poor conductivity and brittleness of the epoxy resin are challenges for fast-growing portable and flexible EMI-shielding applications,such as smart wristband,medical cloth,aerospace,and military equipment.In this study,we explored hybrid nanofillers of single-walled carbon nanotubes(SWCNT)/reduced graphene oxide(rGO)as conductive inks and polyester fabrics(PFs)as a substrate for flexible EMI-shielding composites.The highest electrical conductivity and fracture toughness of the SWCNT/rGO/PF/epoxy composites were 30.2 S m^(−1)and 38.5 MPa m^(1/2),which are~270 and 65%enhancement over those of the composites without SWCNTs,respectively.Excellent mechanical durability was demonstrated by stable electrical conductivity retention during 1000 cycles of bending test.An EMI-shielding effectiveness of~41 dB in the X-band frequency of 8.2-12.4 GHz with a thickness of 0.6 mm was obtained with an EM absorption-dominant behavior over a 0.7 absorption coefficient.These results are attributed to the hierarchical architecture of the macroscale PF skeleton and nanoscale SWCNT/rGO networks,leading to superior EMI-shielding performance.We believe that this approach provides highly flexible and robust EMI-shielding composites for next-generation wearable electronic devices.

关键词： Conductive polymer composites Fracture toughness Flexible composites Absorption-dominated electromagnetic interference shielding

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Ultra-flexible graphene/nylon/PDMS coaxial fiber-shaped multifunctional sensor

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Nano Research 2023年第4期16卷 5541-5547页

作者： Peddathimula Puneetha Siva Pratap Reddy Mallem Sung cheol park Seoha Kim Dong Hun Heo cheol Min Kim Jaesool Shim Sung Jin An Dong-Yeon Lee Kwi-Il park Department of Robotics and Intelligent Machine Engineering/College of Mechanical and IT Engineering Yeungnam UniversityGyeongsan 38541Republic of Korea School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Advanced Material Research Center Kumoh National Institute of TechnologyGumi 39177Republic of Korea School of Mechanical Engineering Yeungnam UniversityGyeongsan 38541Republic of Korea Department of Materials Science and Engineering Kumoh National Institute of TechnologyGumi 39177Republic of Korea

The development of flexible and wearable devices is mainly required for tactile sensing;as such devices can adapt to complicated nonuniform surfaces,they can be applied to the human body.Nevertheless,it remains necessary to simultaneously achieve small-scale,portable,and stable developments in such devices.Thus,this work aims at fabricating a novel,lightweight,ultra-flexible,and fiber-shaped coaxial structure with a diameter of 0.51 mm using polydimethylsiloxane/graphene/nylon material,based on piezoresistive and triboelectric principles.The piezoresistive-based robotic-hand-controlled sensor thus realized exhibits a response time of 120 ms and a fast recovery time of 55 ms.Further,the piezoresistive-based sensors effectively feature whisker/joystick-guided behaviors and also sense the human finger contact.Owing to the triboelectric-based selfpowered nanogenerator behavior,the resulting sensor can convert mechanical motion into electrical energy,without adversely affecting human organs.Moreover,this triboelectric-based human finger sensor can be operated under different bending modes at specific angles.Notably,this multifunctional sensor is cost-effective and suitable for various applications,including robotichand-controlled operations in medical surgery,whisker/joystick motions in lightweight drone technology,and navigation with highsensitivity components.

关键词： extremely lightweight ultra-flexible piezoresistive/triboelectric sensor human-machine whisker

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Anaphylactic shock induced by polyethylene glycol after bowel preparation for the colorectal cancer surgery:A case report

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世界临床病例杂志 2023年第23期11卷 5589-5594页

作者： Go Woon park Nahyeon park Jung cheol Kuk Eung Jin Shin Dae Ro Lim Department of General Surgery Soonchunhyang Bucheon HospitalBucheon 14584South Korea

BACKGROUND Polyethylene glycol(PEG)is widely used as an additive because of its hydrophilic and chemically inert properties.However,there are been increasing reports of PEG allergies,including anaphylaxis,although they are still rare.This case report aims to raise awareness,that the commonly used bowel cleansing agent containing PEG can cause serious allergic reactions.CASE SUMMARY Prior to surgery for sigmoid colon cancer,a 63-year-old man was prescribed a bowel cleansing agent containing PEG.Within 30 min of ingestion,he developed symptoms of anaphylactic shock and did not respond to initial intramuscular epinephrine injection.Under diagnosis of anaphylaxis to PEG,he was stabilized with fluid hydration and continuous norepinephrine infusion.CONCLUSION While allergic reactions to PEG are rare,they can be life-threatening.Therefore,it is crucial for clinicians to be aware of this possibility and to diagnose and resuscitate patients immediately.

关键词： Polyethylene glycol Anaphylaxis Sigmoid colon cancer Bowel preparation Case report

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Effects of homogenization temperature on microstructure and mechanical properties of high-speed-extruded Mg–5Bi–3Al alloy

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Journal of Magnesium and Alloys 2022年第10期10卷 2833-2846页

作者： Jae Won Cha Sang-cheol Jin Jae-Gil Jung Sung Hyuk park School of Materials Science and Engineering Kyungpook National University80 DaehakroDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effects of billet homogenization temperature on the dynamic recrystallization behavior during high-speed extrusion and resultant microstructure and tensile properties of the Mg–5Bi–3Al(BA53,wt%)alloy.Two billets homogenized at 350 and450℃(350H and 450H billets)are extruded at a high speed of 69 m/min.The 350H billet has a relatively smaller grain size and a higher abundance of fine Mg3Bi2particles compared to the 450H billet.During extrusion of the 350H billet,enhanced dynamic recrystallization occurs as a result of its finer grains and abundance of particles,while the growth of recrystallized grains is suppressed by the grain-boundary pinning effect of particles.Ultimately,the extruded 350H material is characterized by smaller grains,relatively greater number of Mg3Bi2particles,and a higher internal strain energy than the extruded 450H material.The tensile strength of the extruded 350H material is higher than that of the extruded 450H material owing to stronger grain-boundary hardening,particle hardening,and strain hardening effects.The extruded 350H material also exhibits a higher tensile elongation as its smaller grains inhibit the formation of crack-inducing undesirable twins during tension.The results from this study demonstrate that a decrease in the homogenization temperature from 450 to 350℃leads to improved strength and ductility in the high-speed-extruded BA53 material.

关键词： Mg–Bi–Al alloy High-speed extrusion Homogenization Dynamic recrystallization Tensile properties

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Orthotic approach to prevention and management of diabetic foot:A narrative review

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World Journal of Diabetes 2022年第11期13卷 912-920页

作者： Min cheol Chang Yoo Jin Choo In Sik park Myung Woo park Du Hwan Kim Rehabilitation Medicine Yeungnam UniversityDaegu 42415South Korea Korean Podiatry and Pedorthics Institute Goyang 10442South Korea Physical Medicine and Rehabilitation Chung-Ang UniversitySeoul 06973South Korea

Diabetic foot is a common complication affecting more than one-fifth of patients with diabetes.If not treated in time,it may lead to diabetic foot ulcers or Charcot arthropathy.For the management of diabetic foot,shoe modifications and orthoses can be used to reduce pressure on the affected foot or provide the foot with increased stability.In addition,the shoe modifications and orthotic devices can relieve patient discomfort during walking.Appropriate shoe modifications include changing the insole material,modifying the heel height,adding a steel shank or rocker sole,and using in-depth shoes.Alternatively,a walking brace or ankle-foot orthosis can be used to reduce the pressure on the affected foot.The purpose of this narrative review was to provide a reference guide to support clinicians in prescribing shoe modifications and foot orthoses to treat diabetic foot ulcers and Charcot arthropathy.

关键词： Diabetic foot Foot ulcers Charcot arthropathy Shoes Foot orthosis

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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 precipitates.However,the addition of Sn significantly decreases the average grain size of the extruded alloy from 123.9 to 75.2μm.The Sn solute atoms inhibit the activity of dislocation slip,which reduces the internal strain energy accumulated in the dynamically recrystallized(DRXed)grains during extrusion.Consequently,this reduced strain energy leads to the decrease in the DRXed grain size owing to weakened grain growth during natural air-cooling.The extruded BT54 alloy exhibits higher tensile strength and ductility than the extruded B5 alloy.The improvement in the strength by the Sn addition is attributed to the combined effects of grain refinement,Sn solute atoms,and increased dislocation density.The 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.

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gscaLCA in R: Fitting Fuzzy Clustering Analysis Incorporated with Generalized Structured Component Analysis

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Computer Modeling in Engineering & Sciences 2022年第9期131卷 801-822页

作者： Ji hoon Ryoo Seohee park Seongeun Kim Heungsun Hwang Department of Education College of Educational SciencesYonsei UniversitySeoul03722South Korea Psychometrics Department American Board of Internal MedicinePhiladelphia19016USA Department of Educational Research Methodology School of EducationUniversity of North Carolina at GreensboroGreensboro27412USA Department of Psychology McGill UniversityMontrealH3A 0G4Canada

Clustering analysis identifying unknown heterogenous subgroups of a population(or a sample)has become increasingly popular along with the popularity of machine learning techniques.Although there are many software packages running clustering analysis,there is a lack of packages conducting clustering analysis within a structural equation modeling framework.The package,gscaLCA which is implemented in the R statistical computing environment,was developed for conducting clustering analysis and has been extended to a latent variable modeling.More specifically,by applying both fuzzy clustering(FC)algorithm and generalized structured component analysis(GSCA),the package gscaLCA computes membership prevalence and item response probabilities as posterior probabilities,which is applicable in mixture modeling such as latent class analysis in statistics.As a hybrid model between data clustering in classifications and model-based mixture modeling approach,fuzzy clusterwise GSCA,denoted as gscaLCA,encompasses many advantages from both methods:(1)soft partitioning from FC and(2)efficiency in estimating model parameters with bootstrap method via resolution of global optimization problem from GSCA.The main function,gscaLCA,works for both binary and ordered categorical variables.In addition,gscaLCA can be used for latent class regression as well.Visualization of profiles of latent classes based on the posterior probabilities is also available in the package gscaLCA.This paper contributes to providing a methodological tool,gscaLCA that applied researchers such as social scientists and medical researchers can apply clustering analysis in their research.

关键词： Fuzzy clustering generalized structured component analysis gscaLCA latent class analysis

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Aging Analysis Framework of Windows-Based Systems through Differential-Analysis of System Snapshots

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Computers, Materials & Continua 2022年第12期73卷 5091-5102页

作者： Eun-Tae Jang Sung hoon Baek Ki-Woong park SysCore Lab Sejong UniversitySeoul05006Korea Department of Computer System Engineering Jungwon UniversityChungcheongbuk-do28024Korea

When aWindows-based system is used for an exceedingly long time,its performance degrades,and the error occurrence rate tends to increase.This is generally called system aging.To investigate the reasons for system aging,various studies have been conducted within the range of the operating system kernel to the user application.However,finding an accurate reason for system performance degradation remains challenging research topic.In this study,system monitoring was conducted by dividing a system into‘before software installation,’‘after software installation,’and‘after software removal.’We confirmed that when a software installed in a system is removed,various system elements,such as storage and memory,are not restored to the level prior to the software installation.Consequently,we established a hypothesis regarding the performance degradation of a computer system owing to repeated software installation/removal operations,investigated the correlation between system aging and repeated software installation/removal operations,and proposed a system aging analysis framework for analyzing the reason behind system aging.In the proposed system aging analysis framework,we aim to forcibly age a Windows-based system by repeating the software installation/removal operation by utilizing the system forced aging module.The framework identifies the elements affecting system performance through a differential data analysis of the system time-series data extracted by the system performance extraction and system component snapshot modules.Consequently,the aging analysis framework presented in this study is expected to be effectively utilized as an index for studying system aging.

关键词： System aging virtual machine system analysis

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Design,fabrication,and structural safety validation of 3D-printable biporous bone augments

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Bio-Design and Manufacturing 2023年第1期6卷 26-37页

作者： Yeokyung Kang Dasol Lim Doo-hoon Sun Jong-Chul park Jungsung Kim Central Research&Development Center Corentec Company Ltd.33-2Banpo-daero 20-gilSeocho-guSeoulRepublic of Korea Cellbiocontrol Laboratory Department of Medical EngineeringYonsei University College of Medicine50-1 Yonsei-roSinchon-dongSeodaemun-guSeoulRepublic of Korea Department of Orthopaedic Surgery Daejeon Sun Hospital10-7 Mok-dongJung-guDaejeonRepublic of Korea

The use of commercial products such as a cup and liner for total hip arthroplasty for patients with severe bone defects has a high probability of failure.In these patients the cup alone cannot cover the bone defect,and thus,an additional augment or cage is required.In this study,we designed three-dimensional(3D)printable bone augments as an alternative to surgeries using reinforcement cages.Thirty-five sharp-edged bone augments of various sizes were 3D printed.A biporous structure was designed to reduce the weight of the augment and to facilitate bone ingrowth.Two types of frames were used to prevent damage to the augment’s porous structure and maintain its stability during printing.Furthermore,two types of holes were provided for easy augment fixation at various angles.Fatigue tests were performed on a combination of worst-case sizes derived using finite element analysis.The test results confirmed the structural stability of the specimens at a load of 5340 N.Although the porosity of the specimens was measured to be 63.70%,it cannot be said that the porous nature was uniformly distributed because porosity tests were performed locally and randomly.In summary,3D-printable biporous bone augments capable of bonding from various angles and bidirectionally through angulation and bottom-plane screw holes are proposed.The mechanical results with bone augments indicate good structural safety in patients.However,further research is necessary to study the clinical applications of the proposed bone augment.

关键词： Bone augment 3D printing Biporous structure Total hip arthroplasty Metal implant

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Ruptured splenic artery aneurysms in pregnancy and usefulness of endovascular treatment in selective patients:A case report and review of literature

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World Journal of Clinical Cases 2022年第25期10卷 9057-9063页

作者： Sang Hun Lee Songsoo Yang Inkyu park Yeong cheol Im Gyu Yeol Kim Department of Obstetrics and Gynecology Ulsan University and Ulsan University HospitalUlsan 44033South Korea Department of Surgery Ulsan University and Ulsan University HospitalUlsan 44033South Korea

BACKGROUND The rupture of a splenic artery aneurysm(SAA)in pregnancy is an uncommon condition.However,it is associated with high mortality rates in pregnant women and fetuses even after surgical treatment.Though the endovascular treatment of SAAs is currently preferred as it can improve the outcomes even in emergent cases,the endovascular treatment of a ruptured SAA during pregnancy has not been reported until date.CASE SUMMARY We report a case of a 33-year-old woman with the sudden onset of epigastric pain due to a ruptured SAA at the mid-portion of the splenic artery at 18 wk of pregnancy.After emergent initial resuscitation,the patient was diagnosed with a ruptured SAA through digital angiography.Immediately upon diagnosis,she underwent emergent endovascular embolization of the splenic artery for the rupture on the spot.Next,surgery was performed to remove the hematoma under stable conditions.Although the fetus was found to be dead during resuscitation,the woman recovered without complications and was discharged 15 d postoperatively.CONCLUSION Endovascular treatment might be a valuable alternative to surgery/lead to safer surgery for selected pregnant patients with ruptured SAAs.

关键词： Splenic artery Aneurysm Pregnancy Endovascular treatment Case report

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