检索结果-南通市图书馆

Laboratory investigation of the anisotropic confinement-dependent brittle-ductile transition of a Utah coal

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2021年第1期31卷 51-57页

作者： Bo-hyun kim Mark K.Larson Mine Safety Branch CDC/NIOSH/SMRDSpokaneWA 99207USA

This paper was developed as part of an effort by the National Institute for Occupational Safety and Health(NIOSH)to identify risk factors associated with bumps in the prevention of fatalities and accidents in highly stressed,bump-prone ground *** of failure mechanism with increasing confinement,from extensional-to shear-dominated failure,are widely observed in the rupture of intact specimens at the laboratory scale and in rock *** the previous analysis conducted in 2018,both unconfined and triaxial compressive tests were conducted to investigate the strength characteristics of some specimens of a Utah coal,including the spalling limits,the ratio of apparent unconfined compressive strength(AUCS)to unconfined compressive strength(UCS),the damage characteristics,and the postyield *** mechanical characteristics were found to be strongly anisotropic as a function of the orientation of the cleats relative to the loading ***,the transition from extensional to shear failure at the given confinements was not clearly *** this study,a total of 20 specimens were additionally prepared from the same coal sample used in the previous study and then tested under both unconfined and triaxial compressive *** different confining stresses are used as analogs for different width-to-height(W/H)ratios of pillar *** the W/H ratios of the specimens were not directly considered during testing,the equivalent W/H ratios of a pillar as a function of the confining stresses were estimated using an existing empirical *** to this relationship,theW/H atwhich in-situ pillar behavior would be expected to transition from brittle to ductile is identified.

关键词： Bump-prone ground conditions A Utah coal Anisotropic Equivalent W/H ratios of a pillar

Horizontal distribution of Changjiang Diluted Water in summer inferred from total suspended sediment in the Yellow Sea and East China Sea

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2015年第12期34卷 44-50页

作者： LEE Dong-Kyu KWON Jae-Il SON seung hyun Pusan National University Coastal Disaster Research Center Korea Institute of Ocean Science and Technology China-Korea Joint Ocean Research Center Cooperative Institute for Research in the Atmosphere Colorado State University

During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment（TSS） can be used as an excellent tracer for Changjiang Diluted Water（CDW）. To analyze the spatial and temporal variations of the CDW distribution, the monthly mean TSS from Moderate Resolution Imaging Spectroradiometer（MODIS） ocean color data are constructed and are converted to salinity using the relationship between salinity observed from AQUARIUS and TSS. The process produces the detailed horizontal distribution of salinity with very high resolution（1 km）. From monthly mean salinity map from 2002 to 2012 in July and August, the expansion patterns of CDW are analyzed. The southerly wind in July and southeasterly wind in August transport the CDW eastward and northeastward, respectively. It is found that the yearly variation of the expansion of CDW toward the southern sea area of Korea is mostly due to the variation of southerly wind and the fluctuations of fresh water discharge into the Changjiang estuary show relatively little impact on the eastward extend of CDW. When 11-year mean（from2002 to 2012） salinity map in August is compared with World Ocean Atlas 2013, it is revealed that wind in August strengthened six times from 1994 and it causes the expansion of CDW extended 150 km further eastward.

关键词： Yellow and East China Seas Changjiang diluted water total suspended sediment MODIS

Microstructure and Mechanical Properties of Hyper-eutectic Al-Si Alloys Fabricated by Spray Casting

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第1期24卷 48-50页

作者： Min Ryou Chul-hyun kim Myung-Ho kim School of Materials Science and Engineering Inha University 253 Yonghyun-DongNam-GuIncheon 402-751Korea Dong Yang Piston Co. LTD 1050Singil-DongDonwon-GuAnsanKyungki-DoKorea

Microstructure and mechanical properties of hyper-eutectic Al-Si alloy fabricated by spray casting were in- vestigated and then these results were compared with those by squeeze *** spray-cast specimen was found to have finer Si particles （～5μm） compared to the squeeze-cast specimen （10-25μm）.The tensile strength and elongation of the spray-cast specimen are also higher than those of the squeeze cast *** was considered that the increased mechanical properties of the spray-cast specimen were mainly due to finer size of the Si particles distributed in Al matrix.

关键词： Hyper-eutectic Al-Si alloy Squeeze casting Spray casting

Direct synthesis of highly conductive poly（3,4- ethylenedioxythiophene）：poly（4-styrenesulfonate）（PEDOT：PSS）/graphene composites and their applications in energy harvesting systems

在线全文

学校读者我要写书评

暂无评论

Nano Research 2014年第5期7卷 717-730页

作者： Dohyuk Yoo Jeonghun kim Jung hyun kim Department of Chemical and Biomolecular Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seou1120-749 Republic of Korea Electronic Materials Division R&D Center Dongjin Semichem Co. Ltd. 625-3 Yodang-Ri Yanggam-Myeon Hwaseong-Gun Gyeonggi-Do Republic of Korea

We report for the first time highly conductive poly（3,4-ethylenedioxythiophene）： poly（4-styrenesulfonate）（PEDOT：PSS）/graphene composites fabricated by in situ polymerization and their applications in a thermoelectric device and a platinum （Pt）-free dye-sensitized solar cell （DSSC） as energy harvesting systems. Graphene was dispersed in a solution of poly（4-styrenesulfonate）（PSS） and polymerization was directly carried out by addition of 3,4-ethylenedioxythiophene （EDOT） monomer to the dispersion. The content of the graphene was varied and optimized to give the highest electrical conductivity. The composite solution was ready to use without any reduction process because reduced graphene oxide was used. The fabricated film had a conductivity of 637 ***-1, corresponding to an enhancement of 41%, after the introduction of 3 wt.% graphene without any further complicated reduction processes of graphene being required. The highly conductive composite films were employed in an organic thermoelectric device, and the device showed a power factor of 45.7 μW·m^-1K^-2 which is 93% higher than a device based on pristine PEDOT：PSS. In addition, the highly conductive composite films were used in Pt-free DSSCs, showing an energy conversion efficiency of 5.4%, which is 21% higher than that of a DSSC based on PEDOT：PSS.

关键词： direct synthesis conductive polymer graphene composite thermoelectric material dye-sensitized solar cell

Reversible and controllable threshold voltage modulation for n-channel MoS2 and p-channel MoTe_(2 )field-effect transistors via multiple counter doping with ODTS/poly-L-lysine charge enhancers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2021年第9期14卷 3214-3227页

作者： seung Gi Seo Jinheon Jeong seung Yeob kim Ajit Kumar Sung Hun Jin Department of Electronic Engineering Incheon National UniversityAcademy-ro 119Yeongsu-guIncheon 22012Republic of Korea

Confronted by the inherent physical limitations in scaling down Si technology,transition metal dichalcogenides(TMDCs)as alternatives are being tremendously researched and paid attention ***,mature counter doping technology for TMDCs is still elusive,and thus,a controllable and reversible charge enhancer is adopted for acceptor(or donor)-like doping via octadecyltrichlorosilane(ODTS)(or poly-L-lysine(PLL))***,multiple counter doping for TMDC field-effect transistors(FETs),combined with a threshold voltage(V;h)freezing scheme,renders the V_(th) modulation controllable,with negligible degradation and decent sustainability of FETs even after each treatment of a representative charge *** parallel,the counter doping mechanism is systematically investigated via photoluminescence spectroscopy,X-ray photoelectron spectroscopy,atomic force microscopy(AFM),surface energy characterization,and measurement of optoelectronic properties under illumination with light of various *** impressively,complementary inverters,composed of type-converted molybdenum ditelluride(MoTe_(2)>FETs and hetero-TMDC FETs in enhancement mode,are demonstrated via respective ODTS/PLL ***,driving backplane application for micro-light-emitting diode(p-LED)displays and physical validation of a corresponding counter doping scheme even for flexible polyethylene terephthalate(PET)substrates could be leveraged to relieve daunting challenges in the application of nanoscale Si-based three-dimensional(3D)stacked systems,with potential adoption of ultralow power and monolithic optical interconnection technology.

关键词： transition metal dichalcogenides(TMDCs) counter doping charge enhancer field-effect transistors micro-light-emitting diode(m-LED)

Prediction of forming limit curve for pure titanium sheet

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2018年第2期28卷 319-327页

作者： Young-Suk kim Bong-hyun LEE seung-Han YANG School of Mechanical Engineering Kyungpook National University Daegu-Gyeongbuk Center Korea Automotive Technology Institute

Commercially pure titanium（CP Ti） has been actively used in the plate heat exchanger due to its light weight, high specific strength, and excellent corrosion resistance. However, researches for the plastic deformation characteristics and press formability of the CP Ti sheet are not much in comparison with automotive steels and aluminum alloys. The mechanical properties and hardening behavior evaluated in stress-strain relation of the CP Ti sheet are clarified in relation with press formability. The flow curve denoting true stress-true strain relation for CP Ti sheet is fitted well by the kim-Tuan hardening equation rather than Voce and Swift models. The forming limit curve（FLC） of CP Ti sheet as a criterion for press formability was experimentally evaluated by punch stretching test and analytically predicted via Hora＇s modified maximum force criterion. The predicted FLC by adopting kim-Tuan hardening model and appropriate yield function shows good correlation with the experimental results of punch stretching test.

关键词： kim-Tuan hardening equation Hora modified maximum force criterion pure titanium sheet forming limit curve

Boosting overall water splitting by incorporating sulfur into NiFe(oxy)hydroxide

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第1期31卷 364-371,I0010页

作者： Chiho kim Seong hyun kim seunghun Lee Ilyeong Kwon Seong hyun kim Shinho kim Changgyu Seok Yoo Sei Park Yangdo kim Department of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea BK21 Four Innovative Graduate Education Program for Global High-tech Materials&PartsPusan National UniversityBusan 46241Republic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH).Pohang 37673Republic of Korea

Developing highly active and cost-effective electrocatalysts for enhancing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a significant challenge for overall water ***-incorporated nickel iron(oxy)hydroxide(S-NiFeOOH)nanosheets were directly grown on commercial nickel foam using a galvanic corrosion method and a hydrothermal *** incorporation of sulfur into NiFeOOH enhanced the catalytic activity for the HER and OER in 1 M KOH *** enhanced catalytic activity is attributed to the change in the local structure and chemical states due to the incorporation of *** performance for overall water splitting was achieved with an alkaline water *** was realized by employing S-NiFeOOH as a bifunctional electrocatalyst,thereby outperforming a water electrolyzer that requires the usage of precious metal electrocatalysts(i.e.,Pt/C as the HER electrocatalyst and IrO_(2) as the OER electrocatalyst).Moreover,when driven by a commercial silicon solar cell,an alkaline water electrolyzer that uses S-NiFeOOH as a bifunctional electrocatalyst generated hydrogen under natural *** study shows that S-NiFeOOH is a promising candidate for a large-scale industrial implementation of hydrogen production for overall water splitting because of its low cost,high activity,and *** addition,the solar-driven water electrolyzer using S-NiFeOOH as a bifunctional electrocatalyst affords the opportunity for developing effective and feasible solar power systems in the future.

关键词： Overall water splitting Hydrogen production Sulfur incorporated NiFe(oxy)hydroxide Electrocatalysts Solar-driven water splitting

Data Augmentation Using Contour Image for Convolutional Neural Network

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第6期75卷 4669-4680页

作者： seung-Yeon Hwang Jeong-Joon kim Department of Computer Engineering Anyang UniversityAnyang-si14058Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14058Korea

With the development of artificial intelligence-related technologies such as deep learning,various organizations,including the government,are making various efforts to generate and manage big data for use in artificial ***,it is difficult to acquire big data due to various social problems and restrictions such as personal information *** are many problems in introducing technology in fields that do not have enough training data necessary to apply deep learning ***,this study proposes a mixed contour data augmentation technique,which is a data augmentation technique using contour images,to solve a problem caused by a lack of ***,a famous convolutional neural network(CNN)architecture,and CIFAR-10,a benchmark data set,are used for experimental performance evaluation to prove the superiority of the proposed *** to prove that high performance improvement can be achieved even with a small training dataset,the ratio of the training dataset was divided into 70%,50%,and 30%for comparative *** a result of applying the mixed contour data augmentation technique,it was possible to achieve a classification accuracy improvement of up to 4.64%and high accuracy even with a small amount of data *** addition,it is expected that the mixed contour data augmentation technique can be applied in various fields by proving the excellence of the proposed data augmentation technique using benchmark datasets.

关键词： Data augmentation image classification deep learning convolutional neural network mixed contour image benchmark dataset

A Universal Activation Function for Deep Learning

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 2023年第5期75卷 3553-3569页

作者： seung-Yeon Hwang Jeong-Joon kim Department of Computer Engineering Anyang UniversityAnyang-si14028Korea Department of ICT Convergence Engineering Anyang UniversityAnyang-si14028Korea

Recently,deep learning has achieved remarkable results in fields that require human cognitive ability,learning ability,and reasoning *** functions are very important because they provide the ability of artificial neural networks to learn complex patterns through *** activation functions are being studied to solve problems such as vanishing gradients and dying nodes that may occur in the deep learning ***,it takes a lot of time and effort for researchers to use the existing activation function in their ***,in this paper,we propose a universal activation function(UA)so that researchers can easily create and apply various activation functions and improve the performance of neural *** can generate new types of activation functions as well as functions like traditional activation functions by properly adjusting three *** famous Convolutional Neural Network(CNN)and benchmark datasetwere used to evaluate the experimental performance of the UA proposed in this *** compared the performance of the artificial neural network to which the traditional activation function is applied and the artificial neural network to which theUA is *** addition,we evaluated the performance of the new activation function generated by adjusting the hyperparameters of *** experimental performance evaluation results showed that the classification performance of CNNs improved by up to 5%through the UA,although most of them showed similar performance to the traditional activation function.

关键词： Deep learning activation function convolutional neural network benchmark datasets universal activation function