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Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

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中国有色金属学会会刊：英文版 2012年第S3期22卷 585-595页

作者： jung-Min lee chan-Joo lee Kyung-Hun lee Byung-Min KIM Dongnam Regional Division Korea Institute of Industrial Technology Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the ***,this indirect measurement occasionally leads to inaccurate properties of the indented *** objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation *** relations between the residual indentation profile and n value of the indented material were identified by dimensional ***,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and *** parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after *** were subsequently characterized as dimensionless functions using n and E/σr ***,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

关键词： nano-indentation pile-up sink-in strain hardening exponent FE simulation

In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction

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Journal of Energy Chemistry 2024年第3期90卷 632-651,I0014页

作者： Andi Haryanto Kyounghoon jung chan Woo lee Dong-Wan Kim Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea School of Civil Environmental and Architectural EngineeringKorea UniversitySeoul 02841Republic of Korea

Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy *** methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic *** this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the *** addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during *** spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER.

关键词： Hydrogen evolution reaction Infrared spectroscopy Raman spectroscopy X-ray absorption spectroscopy Reaction mechanism

Deformation prediction of porcelain-enameled steels with strain history by press forming and high-temperature behavior of coating layer

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中国有色金属学会会刊：英文版 2012年第S3期22卷 838-844页

作者： Young-Ki SON chan-Joo lee jung-Min lee Byung-Min KIM School of Mechanical Engineering Pusan National University Dongnam Regional Division Korea Institute of Industrial Technology

Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of *** typical process to produce enameled steels is roughly divided into two stages:the first stage consists of a forming process to give the desired shape to a steel substrate,and the second stage consists of a firing process to bond enamel frits on the *** firing process requires a high temperature above 800 °C,which may lead to austenitic transformation and severe thermal deformation of the steel *** aim of this study is to develop a finite element analysis (FE analysis) technique to predict the mechanical and thermal deformations of the enameled steels during forming and any further enameling process,including *** FE analysis involves analyzing the strain history of the steel substrate,which comprises the stress and thickness distributions of the substrate and its deformed shape,and the high-temperature behavior of the enamel coating *** validity of the FE analysis is verified through the U-bending test and firing test with various numbers and positions of enamel coating layers on the *** results reveal that the FE analysis results agree well with the experimental results with 8% error.

关键词： porcelain enamel firing process finite element analysis enameled steel thermal deformation

Three-dimensional porous graphene-metal oxide composite microspheres： Preparation and application in Li-ion batteries

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Nano Research 2015年第5期8卷 1584-1594页

作者： Seung Ho Choi jung-Kul lee Yun chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea Department of Chemical Engineering Konkuk University 1 Hwayang-Dong Gwangjin-Gu Seou1143-701 Republic of Korea

The use of new three-dimensional （3D） porous graphene-metal oxide composite microspheres as an anode material for Li-ion batteries （LIBs） is first introduced here. 3D graphene microspheres are aggregates of individual hollow graphene nanospheres composed of graphene sheets. Metal oxide nanocrystals are uniformly distributed over the graphene surface of the microspheres. The 3D porous graphene-SnO2 microspheres are selected as the first target material for investigation because of their superior electrochemical properties. The 3D porous graphene-SnO2 and graphene microspheres and bare SnO2 powders deliver discharge capacities of 1,009, 196, and 52 mAh·g^-1, respectively, after 500 cycles at a current density of 2 A·g^-1 .The 3D porous graphene-SnO2 microspheres exhibit uniquely low charge transfer resistances and high Li-ion diffusivities before and after cycling.

关键词： graphene metal oxide nanostructures electrode material batteries

Effect of esterification reaction of citric acid and ethylene glycol on the formation of multi-shelled cobalt oxide powders with superior electrochemical properties

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Nano Research 2014年第12期7卷 1738-1748页

作者： Gi Dae Park Jong-Heun lee jung-Kul lee Yun chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea Department of Chemical Engineering Konkuk University 1 Hwayang-dong Gwangjin-gu Seou1143-701 Republic of Korea

In this study, for the first time, polymeric precursors have been used in the preparation of yolk-shell powders using a large-scale spray drying process. An esterification reaction between the carboxyl group of citric acid and the hydroxyl group of ethylene glycol inside the droplet produced organic polymers during the drying process of the droplet. During the spray drying process, the polymeric precursors enabled the formation of multi-shell cobalt oxide yolk- shell powders with superior electrochemical properties. The maximum number of shells of the particles in the yolk-shell powders post-treated at 300, 400, and 500 ℃ were six, five, and four, respectively. The initial discharge capacities of the cobalt oxide yolk-shell powders post-treated at 300, 400, and 500 ℃ were 1,188, 1,331, and 1,110 mAh·g^-1, and their initial charge capacities were 868, 1,005, and 798 mAh·g^-1, respectively. The discharge capacities of the powders post- treated at 300, 400, and 500 ℃ after 100 cycles were 815, 958, and 670 mAh·g^-1, respectively and their corresponding capacity retentions measured after the first cycles were 92%, 93%, and 82%, respectively. The pure phase Co3O4 yolk-shell powders post-treated at 400 ℃ had low charge transfer resistance and high lithium-ion diffusion rate.

关键词： yolk-shell energy storage synthesis design lithium battery spray drying

Complete restoration of congenital conductive hearing loss by staged surgery: A case report

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World Journal of Clinical Cases 2021年第33期9卷 10286-10292页

作者： Ji Seob Yoo chan Mi lee Yun Na Yang Eun jung lee Department of Otorhinolaryngology-Head and Neck Surgery Jeonbuk National University College of MedicineJeonju 54907South Korea Biomedical Research Institute Clinical Medicine of Jeonbuk National UniversityJeonbuk National University HospitalJeonju 54907South Korea

BACKGROUND Stapedial tendon ossification is a rare disease,with only a few *** stapedial tendon originates from the apex of the pyramidal eminence and is attached to the neck of the *** stapedial tendon ossification,the stapes is fixed,causing conductive hearing *** most cases,complete hearing restoration is achieved by dividing the stapedial tendon after exploratory *** SUMMARY A 28-year-old woman presented to our hospital with the major complaint of bilateral hearing loss that started during *** tympanotomy was performed due to suspicion of otosclerosis or middle ear *** found bilateral conductive hearing loss due to stapedial tendon ossification with a middle ear anomaly during *** have been several reports of complete recovery of hearing after resection of the stapedial ***,in this case,recovery of hearing was insufficient,even with the division of the stapedial *** the second surgery,the stapes anomaly and footplate fixation were confirmed,and hearing was completely recovered after ***,we report this case with a review of the relevant *** This is the first case of stapedial tendon ossification and fixation of the footplate surgically diagnosed on both *** surgical treatment,successful results are expected.

关键词： Stapedial tendon ossification Middle ear anomaly Footplate fixation Congenital hearing loss Stapedotomy Case report

Increased incidence of indeterminate pancreatic cysts and changes of management pattern: Evidence from nationwide data

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Hepatobiliary & Pancreatic Diseases International 2023年第3期22卷 294-301页

作者： Jaewoo Park Jinkyeong Park Yoon Suk lee Kwangrok jung In Ho jung Jong-chan lee Jin-Hyeok Hwang Jaihwan Kim Department of Internal Medicine Seoul National University Bundang HospitalSeoul National University College of MedicineSeongnamKorea Department of Internal Medicine Kyung Hee University Hospital at GangdongSeoulKorea Department of Internal Medicine Inje University College of MedicineIlsan Paik HospitalGoyangKorea

Background:Pancreatic cysts are ***,most studies are based on data collected from individual *** present study aimed to evaluate the changes of management patterns for pancreatic cystic lesions(PCLs)by analyzing large epidemiologic ***:Between January 2007 and December 2018,information regarding pancreatic cystic lesions was acquired from the nationwide Health Insurance Review and Assessment Service database in ***:The final number of patients with pancreatic cysts was 165277 among the total claims for reimbursement of 855983 associated with PCLs over 12 *** total number of claims were increased from 19453 in 2007 to 155842 in 2018 and the prevalence increased from 0.04%to 0.23%.For 12 years,2874(1.7%)had pancreatic cancer and 8212(5.0%)underwent surgery,and 36 had surgery for twice(total 8248 pancreatectomy).After ruling out claims from the first 3 years of washout period,the incidence increased from 9891 to 24651 and the crude incidence rate of PCLs expanded from 19.96 per 100000 to 47.77 per *** to specific neoplasm codes(D136 or D377),the use of pancreatic cyst code(K862)has been remarkably increased and the most common since *** annual number of pancreatectomies increased from 518 to 861 between 2007 and 2012,and decreased to 596 until *** percentage of pancreatic cancer in patients who received pancreatectomy increased from 5.6%in 2007 to 11.7%in ***:The incidence of PCLs is rapidly *** PCLs,indeterminate cyst is increasing outstandingly.A trend of decreasing in the number of resections and increasing cancer rates among resected cysts may be attributed to the updated international guidelines.

关键词： Pancreatic cyst Incidence Prevalence Pancreatectomy Big data

Intelligent reflecting surface for sum rate enhancement in MIMO systems

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Digital Communications and Networks 2024年第1期10卷 94-100页

作者： chan-Yeob Park Ji-Sung jung Yeong-Rong lee Beom-Sik Shin Hyoung-Kyu Song Department of Information and Communication Engineering Sejong UniversitySeoulGwangjin-guGunja-dong 98Republic of Korea Department of Convergence Engineering for Intelligent Drone Sejong University SeoulGwangjin-guGunja-dong 98Republic of Korea

The research for the Intelligent Reflecting Surface(IRS)which has the advantages of cost and energy efficiency has been *** capacity can be effectively increased by appropriately setting the phase value of IRS elements according to the channel ***,the problem of obtaining an appropriate phase value of IRs is difficult to solve due to the non-convex *** paper proposes an iterative algorithm for the alternating optimal solution in the Single User Multiple-Input-Multiple-Output(SU-MIMO)*** proposed iterative algorithm finds an alternating optimal solution that is the phase value of IRS one by *** results show that the proposed method has better performance than that of the randomized IRS *** number of iterations for maximizing the performance of the proposed algorithm depends on the channel state between the IRS and the receiver.

关键词： Intelligent reflecting surface MIMO Sum rate

Synergic effect of sex pheromone(7R,8S)-cis-7,8-epoxy-2-methyloctadec-17-ene on(+)-disparlure of the Asian gypsy moth,Lymantria dispar, in Korea

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Journal of Forestry Research 2019年第3期30卷 1119-1122页

作者： Il-Kwon Park Hyo-Rim lee chan-Sik jung Sang-Hyun Koh Department of Forest Sciences Seoul National University Seoul 08826Republic of Korea Research Institute of Agriculture and Life Science College of Agriculture and Life SciencesSeoul National University Seoul 08826Republic of Korea Division of Forest Insect Pests and Diseases National Institute of Forest ScienceSeoul 02455Republic of Korea

field attraction test of (7R,8S)-cis-7,8-epoxy-2- methyloctadec-17-ene (= 7R,8S-epo-2me-17ene-18Hy), a trace component of the sex pheromone gland of the Asian gypsy moth,(Lymantria dispar), traps that were baited with the trace component attracted more L. dispar than traps baited with (7S,8R)-cis-7,8-epoxy-2-methyloctadec-17-ene (= 7S,8R-epo-2me-17ene-18Hy) and unbaited traps. However, traps baited with 7R,8S-epo-2me-17ene-18Hy were less attractive than traps baited with (+)-disparlure [=(7R,8S)-cis-7,8-epoxy-2-methyloctadecane], the sex pheromone of L. dispar. Combination tests with (?)-disparlure, 7R,8S-epo-2me-17ene-18Hy, and 7S,8R-epo-2me- 17ene-18Hy revealed that 7R,8S-epo-2me-17ene-18Hy acted synergistically with (?)-disparlure.

关键词： Asian gypsy moth Lymantria dispar Sex pheromone (+)-disparlure (7R,8S)-cis-7,8-epoxy-2methyloctadec-17ene