检索结果-南通市图书馆

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Strain hardening rate dependency of deformation shape,strain distribution,and contact pressure during wire flat rolling

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Investigations for the Surface of the Oxide Semiconductor Changes by Reduction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2016年第5期33卷 84-87页

作者： Bonghoon Kang Sung-tae hwang Department of Visual Optics Far East UniversityChungcheongbuk-doKorea College of Engineering Hansung University

Oxide semiconductor SrTiO3 single crystals are exposed to a reducing atmosphere H2/N2 to induce the reduction of Ti4＋ to Ti3＋ and the release of oxygen from the lattice compensating the reduction of the Ti ions. In a reducing atmosphere H2/N2 the optical edge brings about a red shift. The infrared reflection spectra suggest that the （11） STO single crystal surface can be terminated by the domain of the SrO or TiO2 alternative layer during the reduction. The anisotropy and asymmetry of optical second-harmonic intensity explain a slight shrinkage. The dielectric constant reaches about 6000 and shows almost frequency dependence at all temperatures. With the increasing temperature, the dielectric constant increases rapidly. The high temperature region and low temperature region have activation energies of 0.89 and 1.04, respectively.

关键词： of on in STO as by for

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

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

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

Flexible Memristive Devices Based on Graphene Quantum-Dot Nanocomposites

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Effects of traditional Chinese herbal medicine San-HuangXie-Xin-Tang on gastrointestinal motility in mice

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第4期21卷 1117-1124页

作者： Min Woo hwang tae Seok Ahn Noo Ri Hong Han-Sol Jeong Myeong Ho Jung ki-tae Ha Byung Joo kim Department of Sasang Constitutional Medicine College of Korean MedicineKyung Hee UniversitySeoul 130-701South Korea School of Korean Medicine Pusan National UniversityYangsan 626-870South Korea

AIM: To investigate the effects of San-Huang-Xie-XinTang(SHXXT), a herbal product used in traditional Chinese medicine, on gastrointestinal(GI) motility in ***: The in vivo effects of SHXXT on GI motility were investigated by measuring the intestinal transit rates(ITRs) using Evans blue in normal mice and in mice with experimentally induced GI motility dysfunction(GMD).RESULTS: In normal ICR mice, ITRs were significantly and dose-dependently increased by SHXXT(0.1-1 g/kg). GMD was induced by injecting acetic acid or streptozotocin intraperitoneally. The ITRs of GMD mice were significantly reduced compared to normal mice, and these reductions were significantly and dose-dependently inhibited by SHXXT(0.1-1 g/kg).CONCLUSION: These results suggest that SHXXT is a novel candidate for the development of a prokinetic agent that may prevent or alleviate GMD.

关键词： Gastrointestinal disorders San-Huang-XieXin-Tang M

Recent progress and future research directions for electrochromic zinc-ion batteries

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第3期90卷 220-232,I0007页

作者： tae Gwang Yun Byungil hwang Jun Young Cheong Department of Molecular Science and Technology Ajou UniversitySuwon 16499Republic of Korea School of Integrative Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Bavarian Center for Battery Technology(Bay Batt)and Department of Chemistry University of Bayreuth95447 BayreuthGermany

In recent times,future energy storage systems demand a multitude of functionalities beyond their traditional energy storage *** line with this technological shift,there is active research and development of electrochromic-energy storage systems designed to visualize electrochemical charging and discharging *** conventional electrochromic-energy storage devices primarily integrated supercapacitors,known for their high power density,to enable rapid color ***,the low energy density of supercapacitors restricts overall energy storage capacity,acting as a significant barrier to expanding the application range of such *** this review,we introduce electrochromic zinc(Zn)-ion battery systems,which effectively overcome the limitation of low energy density,and provide illustrative examples of their applicability across diverse *** many recent research works are present for electrochromic Zn-ion batteries,little review has so far taken *** objective is to discuss on the current progress and future directions for electrochromic Zn-ion batteries,which are applicable for wearable electronics applications and energy storage *** review provides an initial milestone for future researchers in electrochromic energy storage and zinc-ion batteries,which will lead to a stream of future works related to them.

关键词： Electrochromic Zn-ion battery Flexible Transition metal oxide Conductive polymer

Electrochemically metal-doped reduced graphene oxide films:Properties and applications

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第5期40卷 72-80页

作者： Myung-Sic Chae tae Ho Lee Kyung Rock Son tae Hoon Park Kyo Seon hwang tae Geun kim School of Electrical Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841South Korea Department of Clinical Pharmacology and Therapeutics College of MedicineKyung Hee UniversitySeoul 02447South Korea

The fine control of doping levels in graphene materials such as reduced graphene oxide(RGO)is important to properly manipulate their ambipolar transport characteristics for various device ***,conventional doping methods involve complex chemical reactions,large-scale doping processes,and poor ***,a simple and controllable electrochemical doping treatment(EDT),performed via the conductive channels created at the RGO surface by the application of an electric field,is introduced to tailor the electrical properties of RGO films.X-ray photoelectron spectroscopy and Raman spectroscopy measurements are performed to detect the presence of Ni atoms in RGO films after the EDT(EDT-RGO).Then,EDT-RGO field-effect transistors(FETs)are fabricated with different doping areas(0 to 100%fractional area)on the RGO active channel to investigate the effect and selective-area doping capability of the *** to p-type doping compensation by the intercalated Ni atoms,the electron mobility of the EDT-RGO FET decreases from 1.40 to 0.12 cm2 V-1s-1 compared with that of the undoped RGO-FET,leading to the conversion from ambipolar to unipolar p-type transfer characteristics.

关键词： Reduced graphene oxide Electrochemical doping treatment Electrical breakdown process Field-effect transistor