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Effect of Nip Force on Ink Transfer in High Resolution Roll-to-Roll Printing
Nguyen Ho Anh Duc,신기현,이창우 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.3
In this paper, the effect of the nip force on the ink transfer in gravure printings was investigated. An adhesive force-based ink transfermodel was suggested. This model is a function of the contact length between the ink and the substrate. The static simulation of theelastic deformation of the substrate was implemented under different nip forces. The simulation showed that the contact length (LIS)was increased as the nip force increased. Accordingly, the ink transfer ratio was increased as the nip force increased due to anincreased contact length LIS. However, the fidelity of the printed pattern at high resolutions could deteriorate if the nip pressure wastoo high, especially when the doctoring ratio was greater than 1. Finally, experiments were conducted to verify the effect of the nipforce, which showed good agreements with predicted results. The results of this study may be used as practical guidelines indetermining the optimal range of the nip force in R2R gravure printing at high resolutions.
Nguyen Hoang Loc,Truong Thi Phuong Lan,Nguyen Duc Huy,Nguyen Ngoc Luong,Hoang Tan Quang,Trinh Huu Tan,Le Thi Anh Thu,Nguyen Xuan Huy 한국식물생명공학회 2019 JOURNAL OF PLANT BIOTECHNOLOGY Vol.46 No.3
The aim of this study is to evaluate the effect of yeast extract (YE) and salicylic acid (SA) on the expression of curcuminoid-biosynthesis genes (CzDCS and CURS1-3), and accumulation of curcumin in Curcuma zedoaria cell cultures. The results showed that, in cells treated with YE or SA, the expression levels of curcuminoid genes were 1.14- to 3.64-fold higher than the control (untreated cells), in which the YE exhibited a stronger effect in comparison with SA. Curcumin accumulation also tended to be similar to gene expression, curcumin contents in YE- or SA-treated cells were 1.61- to 2.53-fold higher than the control. The SA treatment at the fifth day of culture stimulated the curcumin accumulation and expression in all four genes compared to that at the beginning. While the YE treatments gave different results, the CzCURS1 and CzCURS3 genes were expressed strongly in cells that were treated at the beginning. However, the CzDCS and CzCURS2 genes showed the opposite expression pattern, they were activated strongly in the treatments at day five of the culture. However, the content of curcumin reached its maximum value on the fifth day of culture in all investigations.
Hydrodynamic optimization of the impeller and diffuser vane of an axial-flow pump
Duc-Anh Nguyen,마상범,김성,김진혁 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3
Enhancing the hydraulic performance of an axial-flow pump is necessary for increasing the working efficiency and reducing the costs of the pump. In the present study, the impeller and diffuser vane geometry of an axial flow pump are optimized to improve the total efficiency and total head. The internal flow field was obtained by solving the steady-state Reynolds-averaged Navier-Stokes equations in the k-ω shear stress transport reattachment modification turbulence model. The structure was modeled on a hexahedral mesh with a small y+ value at all walls. The total efficiency and total head were chosen as the objective functions in two multi-objective optimizations: one for the impeller with four design variables (shroud chord length, hub chord length, inlet blade angle at mid span, and stagger angle at mid span), the other for the diffuser vane with four design variables (hub radius at the trailing edge, hub position at the leading edge, hub blade angle at the leading edge and middle blade angle at the leading edge). These design variables were selected because they sensitively affect the objective functions, as confirmed using the screening technique based on the 2k factorial method. The blades were optimized by an approximation function based on the following surrogate models: response surface approximation, kriging meta, and a radial basis neural network. After optimizing the impeller, the total efficiency and total head were 0.974 % and 21.028 % higher respectively, than those of the reference impeller, and after optimizing the diffuser vane, the total efficiency and total head were 3.097 % and 10.205 % higher, respectively, than those of the reference model.
Nguyen, Duc Anh,Lee, Yu Rok,Raghu, Anjanapura V,Jeong, Han Mo,Shin, Cheol Min,Kim, Byung Kyu John Wiley Sons, Ltd. 2009 Polymer international Vol.58 No.4
<P>BACKGROUND: Functionalized graphene sheet (FGS) was recently introduced as a new nano-sized conductive filler, but little work has yet examined the possibility of using FGS as a nanofiller in the preparation of polymer nanocomposites. In particular, there are currently no published papers that evaluate polyurethane/FGS nanocomposites. The purpose of this study was to prepare a polyurethane/FGS nanocomposite and examine the morphological and physical properties of the material.</P><P>RESULTS: A cast nanocomposite film was prepared from a mixture of thermoplastic polyurethane (TPU) solution and FGS suspended in methyl ethyl ketone. The FGS dispersed on the nanoscale throughout the TPU matrix and effectively enhanced the conductivity. A nanocomposite containing 2 parts of FGS per 100 parts of TPU had an electrical conductivity of 10<SUP>−4</SUP> S cm<SUP>−1</SUP>, a 10<SUP>7</SUP> times increase over that of pristine TPU. The dynamic mechanical properties showed that the FGS efficiently reinforced the TPU matrix, particularly in the temperature region above the soft segment melt.</P><P>CONCLUSION: Our results show that FGS has a high affinity for TPU, and it could therefore be used effectively in the preparation of TPU/FGS nanocomposites without any further chemical surface treatment. This indicates that FGS is an effective and convenient new material that could be used for the modification of polyurethane. It could also be used in place of other nano-sized conductive fillers, such as carbon nanotubes. Copyright © 2009 Society of Chemical Industry</P>
Nguyen Duc Anh,Pham Van Thanh,Doan Tu Lap,Nguyen Tuan Khai,Tran Van An,Tran Duc Tan,Nguyen Huu An,Dang Nhu Dinh 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.2
Forest fires inflict great losses of human lives and serious damages to ecological systems. Hence, numerous fire detection methods have been proposed, one of which is fire detection based on sensors. However, these methods reveal several limitations when applied in large spaces like forests such as high cost, high level of false alarm, limited battery capacity, and other problems. In this research, we propose a novel forest fire detection method based on image processing and correlation coefficient. Firstly, two fire detection conditions are applied in RGB color space to distinguish between fire pixels and the background. Secondly, the image is converted from RGB to YCbCr color space with two fire detection conditions being applied in this color space. Finally, the correlation coefficient is used to distinguish between fires and objects with fire-like colors. Our proposed algorithm is tested and evaluated on eleven fire and non-fire videos collected from the internet and achieves up to 95.87% and 97.89% of F-score and accuracy respectively in performance evaluation.