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Experimental Investigation of Flexible Hawkmoth-like Wings on the Wing-wake Interaction in Hovering Flight

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Journal of Bionic Engineering 2018年第1期15卷 139-153页

作者： YeongGyun Ryu Jo Won Chang joon Chung Dong-Ha kim Department of Aerospace Engineering Ryerson University Toronto Ontario M5B 2K3 Canada Department of Aeronautical Science and Flight Operation Korea Aerospace University 76 Hanggongdaehak-ro Deogyang-gu Goyang-si Gyeonggi-do 10540 Republic of Korea Aerodynamics Group Korean Air R&D Center Daejeon Metropolitan City 34054 Republic of Korea

To study wing-wake interaction for various wing flexibilities, force measurements and digital particle image velocimetry were carried out on flapping hawkmoth-like wings in a water tank. Wing thickness was employed as a design variable for the wing flexi- bility distributions. Abrupt flap-down and phase delay in flexible wings influenced the behaviors of the Leading-Edge Vortex （LEV） and Trailing-Edge Vortex （TEV）, generated by the previous stroke. While the rigid wing exhibited a detached LEV at the end of the stroke, wing with specific flexibilities obtained attached LEVs. The attached LEVs induced a relatively rapid flow toward the wing surface as a result of encountering the TEV, and the flow caused a higher lift peak. On the other hand, the wings with larger wing deformations generated distinctive changes in LEV and TEV behaviors. The flap-down helped the TEV form closer to the wing surface, and it thus caused a downwash rather than wing-wake interaction. Furthermore, the most flexible wing had a newly-formed pair of LEVs above the wing during the wing reversal, thereby being not able to generate the wing-wake interaction. These results help to understand the different vortex structures generated by flexible wings during the wing reversal and the corresponding effects of wing-wake interaction.

关键词： hovering flight flexible hawkmoth wings wing-wake interaction Digital Particle Image Velocimetry (DPIV)

Multivalent network modifier upregulates bioactivity of multispecies biofilm-resistant polyalkenoate cement

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Bioactive Materials 2022年第8期7卷 219-233页

作者： Ji-Yeong kim Woojin Choi Utkarsh Mangal Ji-Young Seo Tae-Yun Kang Joohee Lee Taeho kim Jung-Yul Cha Kee-joon Lee Kwang-Mahn kim Jin-Man kim Dohyun kim Jae-sung Kwon Jinkee Hong sung-Hwan Choi Department of Orthodontics Institute of Craniofacial DeformityYonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea BK21 FOUR Project Yonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department and Research Institute of Dental Biomaterials and Bioengineering Yonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Johns Hopkins University 3400 N.Charles St.Mason HallBaltimoreMD 21218USA Department of Oral Microbiology and Immunology School of Dentistry and Dental Research InstituteSeoul National UniversitySeoul 08826Republic of Korea Department of Conservative Dentistry Oral Science Research CenterYonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea

Polyalkenoate cement(PAC)is a promising material for regenerative hard tissue *** ionically rich glass component of PAC encourages bioactive interaction *** release of essential ***,PAC bioactivity is restricted owing to(i)structurally inherent cationic network formers and(ii)surface bacterial biofilm *** two factors cause a deficiency in ion release,further complicated by secondary infections and premature therapeutic ***,a multivalent zwitterionic network modifier(mZM)is presented for upregulation of ionic exchange and bioactivity *** introducing a non-zero charged mZM into PACs,an increase in the proportion of non-bridging oxygen *** network modification promotes ion channel formation,causing a multiple-fold increase in ion release and surface deposition of hydroxy-carbonate apatite(ca.74%).Experiments ex vivo and animal models also demonstrate the efficient remineralization ability of the ***,divalent cationic interaction results in bacterial biofilm reduction(ca.68%)while also influencing a shift in the biofilm species composition,which favors commensal ***,PAC modification with mZM offers a promising solution for upregulation of bioactivity,even aiding in customization by targeting site-specific regenerative therapy in future applications.

关键词： Multivalent network modifier Bioactive materials Glass polyalkenoate cement Ion release Remineralization Multispecies biofilm resistance

A novel electrospinning method for self-assembled tree-like fibrous scaffolds:Microenvironment-associated regulation of MSC behavior and bone regeneration

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Journal of Materials Science & Technology 2022年第20期115卷 52-70页

作者： Jeong In kim Ju Yeon kim sung-Ho Kook Jeong-Chae Lee Cluster for Craniofacial Development and Regeneration Research Institute of Oral Biosciences and School of DentistryJeonbuk National UniversityJeonju 54896Republic of Korea Department of Bionanosystem Engineering Jeonbuk National UniversityJeonju 54896Republic of Korea Department of Bioactive Material Sciences Research Center of Bioactive MaterialsJeonbuk National UniversityJeonju 54896Republic of Korea

Numerous studies highlight advantages of electrospun scaffolds in bone tissue engineering,in which cellular behavior is tightly affected by fiber topographical cues of ***,the classic electrospinning setup limits a desired presentation of biomimetic fibrous microenvironments that sense mechanosignaling and regulate stem cell *** aims of this study were to fabricate advanced asspun scaffolds presenting tree-like microfiber/nanonet networks and to evaluate their regulatory potentials on behavior of human mesenchymal stem cells(h MSCs)and bone *** we developed a novel electrospinning setup that allowed the presentation of patterned Trunk microfibers(TMF)and/or branched nanonet fibers(BNn Fs)in biomimetic fibrous *** the cellular mechanisms,anisotropichierarchical topography of TMF controlled behavior of h MSCs through focal adhesion formation and Yesassociated protein(YAP)induction,whereas BNn F disturbed such mechanosensing responses in the *** fiber microenvironment-related expression and nuclear localization of YAP *** correlated with the potentials of as-spun scaffolds to enhance osteogenic differentiation of the h MSCs and alveolar bone defect healing in an animal ***,this study provides an advanced approach of the modified electrospinning setup for presentation of biomimetic fibrillar microenvironments in as-spun scaffolds along with their application in stem cell behavior regulation and regenerative tissue engineering.

关键词： Electrospinning Advanced biomimetic scaffolds Stem cell behavior Mechanosensing Bone tissue engineering

Hopping-Aware Cluster Header Capability for Sensor Relocation in Mobile IoT Networks

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Intelligent Automation & Soft Computing 2023年第5期36卷 1613-1625页

作者： Moonseong kim Jaeyoung Park Young-joon kim Woochan Lee Department of IT Convergence Software Seoul Theological UniversityBucheon14754Korea Department of Computer Engineering Hongik UniversitySeoul04066Korea Department of Electronic Engineering Gachon UniversitySeongnam13120Korea Department of Electrical Engineering Incheon National UniversityIncheon22012Korea

Mobile sensor nodes such as hopping sensors are of critical importance in data ***,the occurrence of sensing holes is unavoidable due to the energy limitation of the ***,it is evident that the relocation of mobile sensors is the most desirable method to recover the sensing *** previous research conducted by the authors so far demonstrated the most realistic hopping sensor relocation scheme,which is suitable for the distributed *** previous studies,the cluster header plays an essential role in detecting the sensing hole and requesting the neighboring cluster to recover the sensing hole that occurred in the sensor ***,the limitations of the cluster header in the previously proposed relocation protocol are not fully *** the cluster header jumps more frequently than non-header nodes,its energy con-sumption is relatively high compared to other ***,it is most likely to lead to header node failure and can lead to data loss on the *** this paper,the jumping ability and energy consumption of the cluster header are seriously *** ability to replace cluster headers in case of failure is also *** results show that the data collection time can be further increased,which demonstrates the validity of the proposed algorithms.

关键词： Hopping sensor mobileinternetofthings relocationprotocol header node numericalsimulation

Factors associated with axial length elongation in high myopia in adults

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International Journal of Ophthalmology(English edition) 2021年第8期14卷 1231-1236页

作者： Hong Kyu kim sung Soo kim Department of Ophthalmology Dankook University HospitalDankook University College of MedicineCheonan 31116Republic of Korea Yonsei University Graduate School of Medicine Seoul 03722Republic of Korea Department of Ophthalmology Severance HospitalInstitute of Vision ResearchYonsei University College of MedicineSeoul 03722Republic of Korea

AIM:To investigate the association of axial length(AL)and ocular factors on AL ***:A retrospective chart review of patients who underwent two or more AL examinations for more than two *** 4 groups were divided according to initial AL(<24 mm,24-26 mm,26-28 mm,≥28 mm).Initial fundus photograph was used to find risk factors associated AL ***:The mean age of the patients was 47.21±7.79 *** remained almost unchanged in the groups with AL<24 mm and 24≤AL<26 *** the contrary,AL increased by 0.011 mm/y in the group with 26≤AL<28 mm and 0.035 mm/y in the group with AL≥28 mm(P<0.001).In high myopia,AL elongation increased in eye with longer AL(r=0.003,P=0.024),female gender(r=0.014,P=0.019),eye with larger peripapillary chorioretinal atrophic area(r=0.002,P=0.019),and smaller vascular arcade angle(r=-0.004,P=0.006).The risk of elongation 0.03 mm/y in high myopia was increased in female gender(P=0.040),and gradually increased in eye with large peripapillary chorioretinal atrophy area(P<0.01).CONCLUSION:AL elongate significantly in the eye with longer AL,female gender,and the eye with larger atrophic area and smaller arcade angle on fundus photography.

关键词： axial length elongation fundus photography high myopia myopic complication

Methodology for predicting the life of plasma-sprayed thermal barrier coating system considering oxidation-induced damage

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Journal of Materials Science & Technology 2022年第10期105卷 45-56页

作者： Keekeun kim Damhyun kim Kibum Park Junghan Yun Chang-sung Seok School of Mechanical Engineering Sungkyunkwan UniversitySuwonGyeonggi 440-746Korea

The lifespan of plasma-sprayed thermal barrier coating(TBC)systems is difficult to predict owing to the variety of microstructures and deterioration *** this study,we developed a novel TBC damage model to reflect deterioration histories;thus,it can be applied to various *** to TBCs is classifed into oxidation and mechanical damage;therefore,a detailed deterioration history can be *** addition,by introducing a virtual S–N diagram,a life prediction model that can be applied to TBCs with various microstructures was *** used the proposed damage and life prediction models in isothermal aging and thermal cycle tests with different aging *** predicted lifespan of TBCs by using the proposed models was within 95%of the results obtained by performing actual tests in the temperature range of 1150–1350℃.

关键词： Thermal barrier coatings Damage model Temperature history Thermal fatigue Life prediction model

Development and application of a multi-step porcine in vitro system to evaluate feedstuffs and feed additives for their efficacy in nutrient digestion, digesta characteristics, and intestinal immune responses

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Animal Nutrition 2024年第2期17卷 265-282页

作者： Hee Yeon kim Jun-Ok Moon sung Woo kim Application Center CJ Blossom Park Department of Animal Science North Carolina State University

In vitro model provides alternatives to the use of live animals in research. In pig nutrition, there has been a tremendous increase in in vivo research over the decades. Proper utilization of in vitro models could provide a screening tool to reduce the needs of in vivo studies, research duration, cost, and the use of animals and feeds. This study aimed to develop a multi-step porcine in vitro system to simulate nutrient digestion and intestinal epithelial immune responses affected by feedstuffs and feed additives. Seven feedstuffs(corn, corn distillers dried grains with solubles [corn DDGS], barley, wheat, soybean meal, soy protein concentrates, and Corynebacterium glutamicum cell mass [CGCM]), feed enzymes(xylanase and phytase), and supplemental amino acids(arginine, methionine, and tryptophan), were used in this in vitro evaluation for their efficacy on digestibility, digesta characteristics, and intestinal health compared with the results from previously published in vivo studies. All in vitro evaluations were triplicated. Data were analyzed using Mixed procedure of SAS9.4. Evaluations included(1) nutrient digestibility of feedstuffs,(2) the effects of feed enzymes, xylanase and phytase, on digestibility of feedstuffs and specific substrates, and(3) the effects of amino acids, arginine, tryptophan, and methionine, on anti-inflammatory, anti-oxidative, and anti-heat stress statuses showing their effects(P < 0.05) on the measured items. Differences in dry matter and crude protein digestibility among the feedstuffs as well as effects of xylanase and phytase were detected(P < 0.05), including xylo-oligosaccharide profiles and phosphorus release from phytate. Supplementation of arginine, tryptophan, and methionine modulated(P < 0.05) cellular inflammatory and oxidative stress responses. The use of this in vitro model allowed the use of 3 experimental replications providing sufficient statistical power at P < 0.05. This indicates in vitro models can have increased prec

关键词： Digestion Feed additive Feedstuff In vitro Intestine Pig

Comparison of the impact of endoscopic retrograde cholangiopancreatography between pre-COVID-19 and current COVID-19 outbreaks in South Korea:Retrospective survey

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World Journal of Clinical Cases 2021年第28期9卷 8404-8412页

作者： Kook Hyun kim sung Bum kim Division of Gastroenterology and HepatologyDepartment of Internal Medicine Yeungnam UniversityCollege of MedicineDaegu 42415South Korea

BACKGROUND The coronavirus disease 2019(COVID-19)outbreak has markedly influenced the endoscopic *** retrograde cholangiopancreatography(ERCP)is an essential technique for pancreatobiliary disease but increases the risk of exposure to the virus-containing body fluid;however,the impact of COVID-19 on ERCP is *** To compare the number of endoscopic activities and to analyze the clinical outcomes of ERCPs before and during the COVID-19 outbreak in Daegu,South *** This retrospective cohort study included patients aged≥18 years who underwent ERCP between February 18 and March 28,2020,at a tertiary *** indications and endoscopic details were compared with those from the same period in 2018 and 2019 as control *** Of the 269 ERCP procedures,113(42.0%)cases were performed as emergency *** number of ERCP procedures in 2018 and 2019 decreased by 20.2%and 56.6%,respectively,compared with that in 2020(P<0.01);among the 113 emergency ERCPs,the observed numbers in 2018(n=42)and 2019(n=55)dramatically dropped by 61.9%and 70.9%,respectively,compared with that in 2020(n=16).Of the 16 cases in 2020,stone removal was performed in five,biliary stenting in five,sphincterotomy in five,and nasobiliary drainage in *** case of ERCP-related infection in medical workers or other patients has been *** The COVID-19 outbreak significantly reduced the number of ERCPs;however,there is no difference in the indications and endoscopic interventions before and during the COVID-19 outbreak.

关键词： Coronavirus disease 2019 Coronavirus Endoscopic retrograde cholangi-opancreatography Emergency endoscopic retrograde cholangiopancreatography Endoscopy

Effect of gastric acid suppressants and prokinetics on peritoneal dialysis-related peritonitis

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World Journal of Gastroenterology 2014年第25期20卷 8187-8194页

作者： Ji Eun Kwon Seong-joon Koh Jaeyoung Chun Ji Won kim Byeong Gwan kim Kook Lae Lee Jong Pil Im Joo sung kim Hyun Chae Jung Department of Internal Medicine and Liver Research Institute Seoul National University College of MedicineSeoul 110-799South Korea Department of Internal Medicine Seoul National University Boramae HospitalSeoul 156-707South Korea

AIM: To investigate the effect of gastric acid suppressants and prokinetics on peritonitis development in peritoneal dialysis(PD) ***: This was a single-center, retrospective study. The medical records of 398 PD patients were collected from January 2000 to September 2012 and analyzed to compare patients with at least one episode of peritonitis(peritonitis group, group A) to patients who never had peritonitis(no peritonitis group, group B). All peritonitis episodes were analyzed to compare peritonitis caused by enteric organisms and peritonitis caused by non-enteric ***: Among the 120 patients who met the inclusion criteria, 61 patients had at least one episode ofperitonitis and 59 patients never experienced peritonitis. Twenty-four of 61 patients(39.3%) in group A and 15 of 59 patients(25.4%) in group B used gastric acid suppressants. Only the use of H2-blocker(H2B) was associated with an increased risk of PD-related peritonitis; the use of proton pump inhibitors, other antacids, and prokinetics was not found to be a significant risk factor for PD-related peritonitis. A total of 81 episodes of peritonitis were divided into enteric peritonitis(EP) or non-enteric peritonitis, depending on the causative organism, and gastric acid suppressants and prokinetics did not increase the risk of EP in PD ***: The use of H2B showed a trend for an increased risk of overall PD-related peritonitis, although further studies are required to clarify the effects of drugs on PD-related peritonitis.

关键词： Proton pump inhibitors Histamine 2 receptor antagonists Gastrointestinal motility Peritoneal dialysis Peritonitis