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Journal of Iron and Steel Research(International) 2023年第3期30卷 475-486页

作者： joong-ki hwang School of Mechatronics Engineering Korea University of Technology and EducationCheonan 31253Republic of Korea

The effect of the strain hardening exponent(n)of a material on the changes in shape,strain inhomogeneity,and contact pressure was investigated during wire flat rolling to understand its effect on the deformation behavior of a flat-rolled wire and to determine the optimal working conditions with *** deformation behaviors of wires with various n values were systematically compared using finite element *** shape of the deformed wire was found to depend on the n value of the *** the contact width and lateral spreading of the wire decrease with increasing n,resulting in a large reduction in area with the n *** strain homogeneity of the wire increases with the n value of the *** improvement in the strain homogeneity with the n value is attributable to two factors:a lower strain concentration in the central region and a higher overall elongation as n *** addition,the average effective strain of the wire cross section decreases with the n value of a material during wire flat *** contact pressure distribution on the surface of the wire differs significantly depending on the n *** materials with a low n value,the contact pressure exhibits a higher value at the entry and edge zones of the contact *** contrast,materials with high n values exhibit a higher contact pressure at the exit *** behavior can be explained by the strain hardening behavior of the material during wire flat rolling.

关键词： Strain hardening exponent Wire flat rolling Shape change Strain inhomogeneity Contact pressure

Effect of drawing speed on microstructure distribution and drawability in twinning-induced plasticity steel during wire drawing

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Journal of Iron and Steel Research(International) 2020年第5期27卷 577-587页

作者： joong-ki hwang School of Mechanical Engineering Tongmyong UniversityBusan 48520Republic of Korea

The effect of drawing speed on temperature rise and microstructure distribution in twinning-induced plasticity(TWIP)steel during wire drawing has been investigated to improve drawability for wire rod *** wire drawing process is performed at room temperature,heat is generated due to the plastic deformation and friction at the wire-die *** steel wires subjected to the low drawing speed(LD)of 0.5 m/min and the high drawing speed(HD)of 5.0 m/min were analyzed using the numerical simulation and electron backscatter diffraction ***,the specimens subjected to the HD had a higher drawability by about 18%compared to the LD,which is totally different from the general behavior of plain carbon pearlitic *** LD wire had uniform temperature distribution along the radial direction during wire *** contrast,the HD wire had a temperature gradient along the radial direction due to the higher frictional effect at surface:the minimum temperature of 58℃ at center area and the maximum temperature of 143 C at surface *** higher stacking fault energy of HD wire at the surface area due to the high temperature rise retarded twinning rate,resulting in the prevention of fast exhaustion in ductility in comparison with the LD wires since the earlier depletion of twins at surface area is known as the main reason for the fracture of TWIP steel during wire ***,HD process delayed the fracture strain of wire and increased the uniformity of microstructure and mechanical properties along the radial direction.

关键词： Twinning-induced plasticity steel Wire drawing Deformation twin Drawing speed Temperature rise

Effect of reduction in area per pass on strain distribution and microstructure during caliber rolling in twinning-induced plasticity steel

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Journal of Iron and Steel Research(International) 2020年第1期27卷 62-74页

作者： joong-ki hwang Sung Jin kim School of Mechanical Engineering Tongmyong UniversityBusan 48520Republic of Korea Department of Advanced Materials Engineering Sunchon National UniversitySuncheon 57922Republic of Korea

The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod *** steel wires subjected to an average RA per pass of 2.5%(skin pass caliber rolling)and 10.0%(conventional caliber rolling)were *** skin pass caliber-rolled wire was characterized as a duplex fiber texture of majorand minor.and the textures were almost same at/between center and surface area,which is totally different from those of conventional caliber rolling and wire *** skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall-Petch hardening,dislocation hardening,and texture behavior with area,resulting in higher formability.

关键词： Twinning-induced plasticity steel Caliber rolling Deformation twin Reduction in area Skin pass

Hydrangea serrata extract exerts tumor inhibitory activity against hepatocellular carcinoma HepG2 cells via inducing p27/CDK2-mediated cell cycle arrest and apoptosis

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Asian Pacific Journal of Tropical Biomedicine 2024年第2期14卷 65-72,I0002-I0005页

作者： Ye-eun kim Jeonghye hwang ki-Young kim Graduate School of Biotechnology Kyung Hee UniversitySeocheonGiheungYonginGyeonggi-do 446-701Republic of Korea Department of Genetics and Biotechnology College of Life SciencesKyung Hee UniversitySeocheonGiheungYonginGyeonggi-do 446-701Republic of Korea

Objective:To examine the inhibitory effect of Hydrangea serrata extract against hepatocellular carcinoma HepG2 cells and its underlying ***:The effects of Hydrangea serrata extract on growth inhibition of tumor cells and spheroids were assessed using MTT and 3D culture *** real-time PCR and Western blot analyses were employed to investigate the changes in mRNA and protein expression levels of molecules related to cell cycle and ***:Hydrangea serrata extract effectively inhibited the growth of both tumor cells and *** extract also significantly upregulated p27 mRNA expression and downregulated CDK2 mRNA expression,leading to cell cycle ***,increased BAX/Bcl-2 ratio as well as caspase-9 and-3 were observed after treatment with Hydrangea serrata extract,indicating the induction of tumor cell ***:Hydrangea serrata extract has the potential to alleviate tumors by effectively modulating cell-cycle-related gene expressions and inducing apoptosis,thereby inhibiting tumor growth.

关键词： Hydrangea serrata Hepatocellular carcinoma Liver cancer Anticancer Cell cycle arrest Apoptosis

Ionizing terahertz waves with 260 MV/cm from scalable optical rectification

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Light(Science & Applications) 2024年第6期13卷 1075-1087页

作者： Hyeongmun kim Chul Kang Dogeun Jang Yulan Roh Sang Hwa Lee joong Wook Lee Jae Hee Sung Seong Ku Lee ki-Yong kim Advanced Photonics Research Institute GISTGwangju61005Korea Department of Physics and Optoelectronics Convergence Research Center Chonnam National UniversityGwangju61186Korea Pohang Accelerator Laboratory POSTECHPohang37673Korea Center for Relativistic Laser Science Institute for Basic ScienceGwangju61005Korea Institute for Research in Electronics and Applied Physics Department of PhysicsUniversity of MarylandCollege ParkMaryland20742USA

Terahertz(THz)waves,known as non-ionizing radiation owing to their low photon energies,can actually ionize atoms and molecules when a sufficiently large number of THz photons are concentrated in time and ***,we demonstrate the generation of ionizing,multicycle,15-THz waves emitted from large-area lithium niobate crystals via phase-matched optical rectification of 150-terawatt laser pulses.A complete characterization of the generated THz waves in energy,pulse duration,and focal spot size shows that the field strength can reach up to 260 megavolts per *** particular,a single-shot THz interferometer is employed to measure the THz pulse duration and spectrum with complementary numerical *** intense THz pulses are irradiated onto various solid targets to demonstrate THz-induced tunneling ionization and plasma *** study also discusses the potential of nonperturbative THz-driven ionization in gases,which will open up new opportunities,including nonlinear and relativistic THz physics in plasma.

关键词： optical interferometer matched

Highly Elastic,Bioresorbable Polymeric Materials for Stretchable,Transient Electronic Systems

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Nano-Micro Letters 2024年第6期16卷 1-13页

作者： Jeong‑Woong Shin Dong‑Je kim Tae‑Min Jang Won Bae Han joong Hoon Lee Gwan‑Jin Ko Seung Min Yang Kaveti Rajaram Sungkeun Han Heeseok Kang Jun Hyeon Lim Chan‑Hwi Eom Amay J.Bandodkar Hanul Min Suk‑Won hwang KU‑kiST Graduate School of Converging Science and Technology Korea University145 Anam‑roSeongbuk‑guSeoul 02841Republic of Korea SK Hynix 2091Gyeongchung‑daeroBubal‑eupIcheon‑siGyeonggi‑do 17336Republic of Korea Hanwha Systems Co. Ltd.188Pangyoyeok‑roBundang‑guSeongnam‑siGyeonggi‑do 13524Republic of Korea Department of Electrical and Computer Engineering North Carolina State UniversityRaleighNC 27606USA Center for Advanced Self‑Powered Systems of Integrated Sensors and Technologies(ASSIST) North Carolina State UniversityRaleighNC 27606USA Department of Integrative Energy Engineering Korea University145 Anam‑roSeongbuk‑guSeoul 02841Republic of Korea Biomaterials Research Center Korea Institute of Science and Technology(KIST)5 Hwarang‑ro 14‑gilSeongbuk‑guSeoul 02792Republic of Korea Semiconductor R&D Center Samsung Electronics Co.Ltd.Hwaseong‑siGyeonggi‑do 18448Republic of Korea Center for Advanced Biomolecular Recognition Biomedical Research DivisionKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea

Substrates or encapsulants in soft and stretchable formats are key components for transient,bioresorbable electronic systems;however,elastomeric polymers with desired mechanical and biochemical properties are very limited compared to nontransient ***,we introduce a bioresorbable elastomer,poly(glycolide-co-ε-caprolactone)(PGCL),that contains excellent material properties including high elongation-at-break(<1300%),resilience and toughness,and tunable dissolution *** of PGCLs as polymer matrices,in combination with conducing polymers,yields stretchable,conductive composites for degradable interconnects,sensors,and actuators,which can reliably function under external *** of device components with wireless modules demonstrates elastic,transient electronic suture system with on-demand drug delivery for rapid recovery of postsurgical wounds in soft,time-dynamic tissues.

关键词： Biodegradable elastomer Conductive polymer composites Biomedical device Transient electronics

Flexible Memristive Devices Based on Graphene Quantum-Dot Nanocomposites

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Computers, Materials & Continua 2022年第8期72卷 3283-3297页

作者： Sung Won hwang Dae-ki Hong Department of System Semiconductor Engineering SangMyung UniversityCheonan-si31066Korea

Artificial neural networks(ANNs)are attracting attention for their high performance in various fields,because increasing the network size improves its *** large-scale neural networks are difficult to implement on custom hardware,a two-dimensional(2D)structure is applied to an ANN in the form of a *** demonstrate a synapse crossbar device from recent research by applying a memristive system to neuromorphic *** system is designed using two-dimensional structures,graphene quantum dots(GQDs)and graphene oxide(GO).Raman spectrum analysis results indicate a D-band of 1421 cm^(−1) that occurs in the disorder;band is expressed as an atomic characteristic of carbon in the sp2 hybridized *** is also a G-band of 1518 cm^(−1) that corresponds to the graphite *** G bands measured for RGO-GQDs present significant GQD edge-dependent shifts with *** avoid an abruptly-formed conduction path,effect of barrier layer on graphene/ITO interface was *** confirmed the variation in the nanostructure in the RGO-GQD layers by analyzing them using *** applying a negative bias to the electrode,a crystalline RGO-GQD region formed,which a conductive ***,a synaptic array for a neuromorphic chip with GQDs applied was demonstrated using a crossbar array.

关键词： Memristive devices neuromorphic chip resistive RAM quantum dot graphene

Performance Evaluation of Composite Electrolyte with GQD for All-Solid-State Lithium Batteries

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Computers, Materials & Continua 2023年第1期74卷 55-66页

作者： Sung Won hwang Dae-ki Hong Department of System Semiconductor Engineering SangMyung UniversityCheonan-si31066Korea

The use a stabilized lithium structure as cathode material for batteries could be a fundamental alternative in the development of next-generation energy storage ***,the lithium structure severely limits battery life causes safety concerns due to the growth of lithium(Li)dendrites during rapid charge/discharge *** electrolytes,which are used in highdensity energy storage devices and avoid the instability of liquid electrolytes,can be a promising alternative for next-generation ***,poor lithium ion conductivity and structural defects at room temperature have been pointed out as *** this study,through the application of a low-dimensional graphene quantum dot(GQD)layer structure,stable operation characteristics were demonstrated based on Li^(+)ion conductivity and excellent electrochemical ***,the device based on the modified graphene quantum dots(GQDs)in solid state exhibited retention properties of 95.3%for 100 cycles at 0.5 C and room temperature(RT).Transmission electronmicroscopy analysis was performed to elucidate the Li^(+)ion action mechanism in the modified GQD/electrolyte *** low-dimensional structure of theGQD-based solid electrolyte has provided an important strategy for stably-scalable solid-state lithium battery applications at room *** was demonstrated that lithiated graphene quantum dots(Li-GQDs)inhibit the growth of Li dendrites by regulating the modified Li^(+)ion flux during charge/discharge cycling at current densities of 2.2–5.5 mA cm,acting as a modified Li diffusion heterointerface.A full Li GQDbased device was fabricated to demonstrate the practicality of the modified Li structure using the Li–GQD *** study indicates that the low-dimensional carbon structure in Li–GQDs can be an effective approach for stabilization of solid-state Li matrix architecture.

关键词： Solid-state lithium batteries composite electrolyte quantum dot graphene

Morbidity analysis of left hepatic trisectionectomy for hepatobiliary disease and live donor

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Hepatobiliary & Pancreatic Diseases International 2022年第4期21卷 362-369页

作者： Young-In Yoon Sung-Gyu Lee Deok-Bog Moon Shin hwang ki-Hun kim Hui-Ju kim ki-Hoon Choi Division of Hepatobiliary Surgery and Liver Transplantation Department of SurgeryAsan Medical CenterUniversity of Ulsan College of Medicine388-1 Poongnap-dongSongpa-guSeoul 138-736Korea Department of Surgery Gold Coast University HospitalSouthportQLD 4215Australia

Background:Despite remarkable advances in surgical techniques and perioperative management,left hepatic trisectionectomy(LHT)remains a challenging procedure with a somewhat high postoperative morbidity rate compared with less-extensive *** study aimed to analyze the short-and long-term outcomes of LHT and identify factors associated with the postoperative morbidity of this technically demanding surgical ***:The medical records of 53 patients who underwent LHT between June 2005 and October 2019 at a single institution were retrospectively *** independent prognostic factor of postoperative morbidity was analyzed using the logistic regression ***:Hepatocellular carcinoma was the most common indication for surgery(n=21),followed by hilar cholangiocarcinoma(n=14),intrahepatic cholangiocarcinoma(n=10),and other pathologies(including colorectal liver metastasis,hepatolithiasis,gallbladder cancer,living donor,hemangioma,and multilocular biliary cyst;n=8).The rates of postoperative morbidities of Clavien-Dindo grade 3 or higher and 90-day mortality were 39.6% and 1.9%,*** 1-,3-,and 5-year overall survival rates were 81.1%,61.4%,and 44.6%,*** analysis revealed that preoperative jaundice[hazard ratio(HR)=6.15,95%confidence interval(CI):1.57-24.17,P=0.009]and operative time>420 min(HR=4.66,95%CI:1.27–17.17,P=0.021)were independent predictors of postoperative ***:The in-hospital mortality of LHT surgery can be minimalized by a reliable preoperative evaluation of liver function and selection of the dominant anatomic features of right posterior sector,active and appropriate preoperative management for obstructive cholangitis and compensatory hypertrophy of the future remnant posterior sector,and the experience of the surgeon.

关键词： Left hepatic trisectionectomy Major hepatectomy Liver neoplasms Survival rate Morbidity

Publisher Correction to:Highly Elastic,Bioresorbable Polymeric Materials for Stretchable,Transient Electronic Systems

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Nano-Micro Letters 2024年第8期16卷 417-417页

作者： Jeong‑Woong Shin Dong‑Je kim Tae‑Min Jang Won Bae Han joong Hoon Lee Gwan‑Jin Ko Seung Min Yang Kaveti Rajaram Sungkeun Han Heeseok Kang Jun Hyeon Lim Chan‑Hwi Eom Amay JBandodkar Hanul Min Suk‑Won hwang KU‑kiST Graduate School of Converging Science and Technology Korea University145 Anam‑roSeongbuk‑guSeoul 02841Republic of Korea SK Hynix 2091Gyeongchung‑daeroBubal‑eupIcheon‑siGyeonggi‑do 17336Republic of Korea Hanwha Systems Co. Ltd.188Pangyoyeok‑roBundang‑guSeongnam‑siGyeonggi‑do 13524Republic of Korea Department of Electrical and Computer Engineering North Carolina State UniversityRaleighNC 27606USA Center for Advanced Self‑Powered Systems of Integrated Sensors and Technologies(ASSIST) North Carolina State UniversityRaleighNC 27606USA Department of Integrative Energy Engineering Korea University145 Anam‑roSeongbuk‑guSeoul 02841Republic of Korea Biomaterials Research Center Korea Institute of Science and Technology(KIST)5 Hwarang‑ro 14‑gilSeongbuk‑guSeoul 02792Republic of Korea Semiconductor R&D Center Samsung Electronics Co.Ltd.Hwaseong‑siGyeonggi‑do 18448Republic of Korea Center for Advanced Biomolecular Recognition Biomedical Research DivisionKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea

Due to typesetting mistake,Hanul Min was missed to be denoted as a corresponding author in the *** type-setter apologizes for *** original article has been *** Access This article is licensed under a Creative Commons Attribution 4.0 International License,which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons licence,and indicate if changes were *** images or other third party material in this article are included in the article’s Creative Commons licence,unless indicated otherwise in a credit line to the *** material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use,you will need to obtain permission directly from the copyright holder.

关键词： Creative Elastic Highly