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Kedong Zhang,Xuhong Guo,Chengdong Wang,Xiangfeng Meng,Lining Sun,Youqiang Xing 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.5
During the dry post-machining processing of selective laser melting (SLM)-produced stainless steel with TiAlN coated tool, the elements of stainless steel chips can diff use and adhere into the coated tool surface, causing serious adhesive wear. In this study, to inhibit the adhesion problem at the tool-chip interface, surface textures with different scales (micro-, nano- and micro/nano-textures) are produced on tool rake face by laser processing before and after physical vapor deposition (PVD) TiAlN coatings deposition. To investigate the cutting performance of these developed coated tools, dry machining tests of the SLM-produced stainless steel are carried out. And, the mechanical properties of textured TiAlN coatings such as the hardness, elastic modulus and critical load are also studied to explain the results from the machining tests. It can be found that the anti-adhesive wear performance of TiAlN coated tool is improved by laser surface texturing. The texture dimension significantly affects the mechanical properties and dry cutting performance of the TiAlN coated tool, and the micro/nanotextures are found to be optimum. Meanwhile, the sequence of surface textures also has an effect on the wear performance of the developed TiAlN coated tools. In the experiment, laser surface texturing before coatings is effective in acting as a barrier against flaking of the TiAlN fi lm, providing a higher active surface for the subsequent TiAlN coatings and presenting a higher compressive residual stress. Thus, the developed cutting tool which is textured before TiAlN coatings deposition presents a milder wear compared to the developed one which is textured after TiAlN coatings deposition.
The Binarization of Text Regions in Natural Scene Images, based on Stroke Width Estimation
김정환,이귀상,Zhang, Chengdong,Kim, Jung Hwan,Lee, Guee Sang 한국스마트미디어학회 2012 스마트미디어저널 Vol.1 No.4
In this paper, a novel text binarization is presented that can deal with some complex conditions, such as shadows, non-uniform illumination due to highlight or object projection, and messy backgrounds. To locate the target text region, a focus line is assumed to pass through a text region. Next, connected component analysis and stroke width estimation based on location information of the focus line is used to locate the bounding box of the text region, and each box of connected components. A series of classifications are applied to identify whether each CC(Connected component) is text or non-text. Also, a modified K-means clustering method based on an HCL color space is applied to reduce the color dimension. A text binarization procedure based on location of text component and seed color pixel is then used to generate the final result.
Jian He,Xulin Hu,Luyao Xing,Dongliang Chen,Lijun Peng,Gaofeng Liang,Chengdong Xiong,Xiangchun Zhang,Lifang Zhang 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.99 No.-
Tissue-engineered scaffolds acted as active natural extracellular matrices that allowed for cellattachment, migration, proliferation, and differentiation. To enhance the drug loading, degradationcontrol, and mechanical features of tissue-engineered scaffolds used in bone regeneration applications,we synthesized novel poly(trimethylene carbonate) (PTMC)/modified HA nanoparticles (KHA NPs,modified by silane coupling agent)/vancomycin hydrochloride (VH) porous microspheres scaffold. Thefabricated PTMC/KHA/VH scaffold has unique surface corrosion degradation, excellent surface properties,and high cytocompatibility. The novel PTMC/KHA/VH scaffold was characterized by 42% porosity,100 mmpore size, and 208.2 MPa compressive modulus. After the treatment of a rat femur defect for 4, 8, and 12weeks, the surface corrosion biodegraded of the PTMC/KHA/VH scaffold remarkably decreasedinflammation response and promoted bone regeneration, suggesting its use as a bioactive structurein bone tissue engineering.
Xiliang Liu,Song Liu,Youkun Fan,Jin Qi,Xin Wang,Wei Bai,Dongliang Chen,Chengdong Xiong,Lifang Zhang 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-
The poly(L-lactide-co-e-caprolactone) (PLCL) ureteral stent creeps and loses shape stability, increasingthe risk of stent tube dislocation. The rubbery biodegradable cross-linked PLCL networks were preparedthrough gamma irradiation under vacuum in the presence of trimethylolpropane triacrylate (TMPTA),pentaerythritol tetraacrylate (PET4A), and pentaerythritol triacrylate (PETA). At a standard sterilizationdose of 25 kGy, the gel content and network density of PLCL networks increased with increasingcrosslinking agent content (1, 3, 5, 7 wt%), and crosslinking efficiency decreased in the order ofPETA > PET4A > TMPTA. The average molecular weight (Mc ) between two crosslinks ranged from 2000to 105 g/mol. To perform the beneficial semi-interpenetrated polymer network and characterized bythe principle, the networks were processed in several doses (25, 50, 75, 100, and 125 kGy). In place ofthe Charlesby-Pinner equation, the irradiation cross-linking followed the Chen-Liu-Tang equation. ThePLCL network with 7 wt% PETA had a gel fraction of 83%, tensile strength of 34.7 MPa, and tensile setvalue as low as 5%. Furthermore, degradation in vitro was slowed down. Thus, PLCL networks with appropriateelasticity and flexibility, inherent biodegradability, and excellent biocompatibility can provide apromising alternative method for soft tissue repair engineering, such as ureteral stents.