Identification of the Plastic Deformation Characteristics of AL5052-O Sheet Based on the Non-Associated Flow Rule

Quoc Tuan Pham,김영숙 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.2

This study aims to determine the plastic deformation characteristics of aluminum 5052-O based on non-associatedflow rule. To achieve this goal, a new strain hardening model named as Kim-Tuan hardening modelis proposed to perfectly describe the stress-strain relation of the studied material in terms of the uniaxial tensiletest and to predict the material’s post-necking behavior. Additionally, the plastic behaviors of AL5052-O sheetare described by two approaches: the associated flow rule with YLD2000-2d yield function and the nonassociatedflow rule with Hill's quadratic function (NAFR-Hill48). The parameters of these functions werederived from the material properties that were obtained from uniaxial tensile tests and bulge test. The flow curvebased on Kim-Tuan model and plastic behaviors obtained from two above-mentioned approaches were importedinto a finite element analysis code to simulate the hydraulic bulge test for this material to confirm the precisionof material characteristics achieved before. The simulation results based on the NAFR-Hill48 match wellwith the experiment results of bulge test while the YLD2000-2d provides highly accurate predictions foranisotropy of this material.

Determining the Required Vitamin D Level for Bone Health Based on Bone Turnover Markers

Tuan Salwani Tuan Ismail,Bayani Che Muda,Roznie Aida Mohd Rosdi,Azalina Zainuddin,Salbiah Isa,Zulkarnain Mustapaha 대한임상검사과학회 2017 대한임상검사과학회지(KJCLS) Vol.49 No.4

To date, no clear threshold that has been established for defining an adequate store of vitamin D for bone health. Therefore, this study aims to determine the required level of vitamin D to maintain a healthy skeleton based on bone remodelling process among healthy adult population. This was a cross sectional study, involving a healthy adult population in Kota Bharu, Malaysia, aged 18∼50 years. We measured serum 25(OH)D (vitamin D), serum parathyroid hormone (PTH), serum C-terminal telopeptide of type 1 collagen (CTX), and Procollagen 1 Intact N-Terminal (P1NP) in 120 healthy adults selected via multi stage sampling (64 males, 56 females) from 6 subdistricts in Kota Bharu. The mean level of 25(OH)D was 23.50 (±8.74) nmol/L. There was a significant difference of the vitamin D level between genders (26.81±8.3 nmol/L vs 19.72±7.68 nmol/L in males and females respectively) (p value<0.001). More than 50% of female subjects had 25(OH)D less than 20 nmol/L, while only 20.3% of male subjects had 25(OH)D below 20 nmol/L. Based on the LOESS plot, the bone turnover markers showed a plateauing result, at the 25(OH)D level of 35 nmol/L for CTX and 20 nmol/L for P1NP. Contrastingly, PTH showed a step rise in the 25(OH)D level of 20 nmol/L. Based on the LOESS plot for CTX, P1NP and PTH versus 25(OH)D, level of vitamin D between 20 to 35 nmol/L is recommended to maintain healthy skeleton.

Determining the Required Vitamin D Level for Bone Health Based on Bone Turnover Markers

Ismail, Tuan Salwani Tuan,Muda, Bayani Che,Rosdi, Roznie Aida Mohd,Zainuddin, Azalina,Isa, Salbiah,Mustapaha, Zulkarnain Korean Society for Clinical Laboratory Science 2017 대한임상검사과학회지(KJCLS) Vol.49 No.4

To date, no clear threshold that has been established for defining an adequate store of vitamin D for bone health. Therefore, this study aims to determine the required level of vitamin D to maintain a healthy skeleton based on bone remodelling process among healthy adult population. This was a cross sectional study, involving a healthy adult population in Kota Bharu, Malaysia, aged 18~50 years. We measured serum 25(OH)D (vitamin D), serum parathyroid hormone (PTH), serum C-terminal telopeptide of type 1 collagen (CTX), and Procollagen 1 Intact N-Terminal (P1NP) in 120 healthy adults selected via multi stage sampling (64 males, 56 females) from 6 subdistricts in Kota Bharu. The mean level of 25(OH)D was 23.50 (${\pm}8.74$) nmol/L. There was a significant difference of the vitamin D level between genders ($26.81{\pm}8.3nmol/L$ vs $19.72{\pm}7.68nmol/L$ in males and females respectively) (p value<0.001). More than 50% of female subjects had 25(OH)D less than 20 nmol/L, while only 20.3% of male subjects had 25(OH)D below 20 nmol/L. Based on the LOESS plot, the bone turnover markers showed a plateauing result, at the 25(OH)D level of 35 nmol/L for CTX and 20 nmol/L for P1NP. Contrastingly, PTH showed a step rise in the 25(OH)D level of 20 nmol/L. Based on the LOESS plot for CTX, P1NP and PTH versus 25(OH)D, level of vitamin D between 20 to 35 nmol/L is recommended to maintain healthy skeleton.

Factors Affecting the Use of ICT in Resolving Work of Community Officers in Vietnam

Truong Tuan LINH(Truong Tuan LINH ),Nguyen Thi Thanh HUYEN(Nguyen Thi Thanh HUYEN ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.2

In general, using information and communication technology (ICT) to support problem-solving is becoming increasingly common across various industries, sectors, and regions. However, there have been few analyses on the factors affecting ICT problem-solving among officers working at People’s Committees of mountainous communes. Using survey data, exploratory factor analysis (EFA), and multivariable linear regression, this study examined the factors that influence the use of ICT in resolving works among community officers at People’s Committees in the Northwest mountainous region of Vietnam. The results showed that three factors with statistical significance affecting the dependent variable are computer skills, gender, and occupation of community officers. Therefore, it is recommended that officers participate in ICT training courses or engage in regular self-study to improve their computer skills and qualifications. Both men and women should also prioritize the use of ICT equipment. The study also found that officers in managerial positions were more likely to use ICT for problem-solving than their counterparts. However, some factors that affect the use of ICT were not identified in this study, leaving room for further research.

Degradation Of Oxytetracycline In Saturated Porous Media By In Situ Chemical Oxidation Using Oxygen Doped Graphitic Carbon Nitride And Peroxymonosulfate

Thanh Tuan Nguyen(NGUYEN THANH TUAN),Seok-Oh Ko(고석오),Do Gun Kim(김도군) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11

Characterization of the isotropic-distortional hardening model and its application to commercially pure titanium sheets

Pham, Quoc Tuan,Lee, Myoung Gyu,Kim, Young Suk Pergamon Press 2019 International journal of mechanical sciences Vol.160 No.-

<P><B>Abstract</B></P> <P>Commercially pure titanium sheets have been widely used in various industrial applications owing to their lightweight nature, superior formability, and excellent corrosion resistance. Previous studies showed that accurate modelling of material characteristics, such as anisotropic yield function and hardening, is essential for the simulation of sheet metal forming with titanium sheets. For example, the non-quadratic anisotropic yield function Yld2000-2d and the modified Kim–Tuan hardening model were used to model initial anisotropy and reproduce flow stress curves at large strains. However, even with these advanced constitutive models for describing the anisotropic behavior of sheet metals, further improvement is necessary to simulate anisotropy evolution, or distortional hardening, in pure titanium sheets. In this study, distortional hardening was experimentally measured under both uniaxial and balanced biaxial loading conditions. Moreover, the evolution of the Yld2000-2d function was modelled as a function of equivalent plastic work. For validation, the developed material models were applied in finite element simulations to analyse deformation behavior in uniaxial tension, hydraulic bulge, and punch-stretching tests. It was confirmed that this approach accurately described material response during these three tests.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Experimental observation of distortional hardening behaviour and three-stage deformation behavior for a pure titanium sheet. </LI> <LI> A procedure to reproduce these material behaviours for the tested material by using an evolutionary yld2000-2d yield function and modified Kim–Tuan hardening law. </LI> <LI> Simulation results of uniaxial tensile tests, hydraulic bulge test, and punch-stretching tests match well with experimental data. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Evaluation of Press Formability of Pure Titanium Sheets

Pham, Quoc Tuan,Kim, Young Suk Trans Tech Publications, Ltd. 2016 Key Engineering Materials Vol.716 No.-

<P>Commercially pure titanium (CP Ti) has been actively used in plate heat exchangers due to its light weight, high specific strength, and excellent corrosion resistance. However compared with automotive steels and aluminum alloys, only limited research has been conducted on the plastic deformation characteristics and press formability of CP Ti sheets. In this study, the mechanical properties, including the anisotropic property and the stress-strain relation, of the CP Ti sheet are clarified in relation to press formability. A new proposed strain hardening model, Kim-Tuan equation, is successful in perfectly describing the stress evaluation for strain increment of this material during strain path. The forming limit curve (FLC) of the CP Ti sheet as a criterion for press formability was experimentally evaluated by punch stretching testing and analytically predicted via Hora’s modified maximum force criterion. The predicted FLC based on the Kim-Tuan strain hardening equation and the appropriate yield function correlates well with the experimental results of the punch stretching test.</P>

Influence of the post-necking prediction of hardening law on the theoretical forming limit curve of aluminium sheets

Pham, Quoc-Tuan,Lee, Bong-Hyun,Park, Kee-Cheol,Kim, Young-Suk Elsevier 2018 International journal of mechanical sciences Vol.140 No.-

<P><B>Abstract</B></P> <P>This study clarified the influence of the post-necking prediction of the hardening law on the theoretical forming limit curve (FLC) of aluminium sheets subjected to punch-stretching tests. A procedure was developed to identify the parameters of a recently developed hardening model (Kim–Tuan hardening model) based on the curve fitting method. Subsequently, this model was used to capture the post-necking behaviours of two aluminium alloy sheets (AL5052-O and AL6016-T4), which were compared with those of various other hardening models, including the Swift model, Voce model, Hockett–Sherby model, Ghosh model, and a linear combination of the Swift and Voce models. These hardening models, with their extrapolations for post-necking prediction, were employed to analytically calculate the FLCs of the tested materials based on the modified maximum force criterion (MMFC). Furthermore, a simple and effective method was found to estimate the level of limited strain in the plane strain mode, namely FLC<SUB>0</SUB>. The proposed method was used to clarify the influence of the hardening law and yield function on the level of the computed FLC. The results indicated that the flow curves predicted by the Kim–Tuan hardening model effectively matched the experimental data obtained from uniaxial tensile tests, while their extrapolations provided intermediate predictions of the post-necking behaviour between the flow curves of the Swift and Voce models. In addition, the proposed hardening model improved the accuracy of the computed FLC for the studied materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New formulation for strain hardening function is presented. </LI> <LI> A procedure for identifying parameters of proposed hardening model is developed based on curve fitting method. In this procedure, stress and strain data obtained from standard uniaxial tensile test were utilized. </LI> <LI> New method is presented for estimating the level of limited strain in the plane strain mode, FLC<SUB>0</SUB>. Based on this method, influence of post-necking prediction of hardening law on forming limit curve of aluminium sheet is discussed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Targeted and controlled drug deliveryl system loading artersunate for effective chemotherapy on CD44 overxpressing cancer cells

( Tuan Hiep Tran ),( Tuan Duc Nguyen ),( Han Van Nguyen ),( Hanh Thuy Nguyen ),( Jong Oh Kim ),( Chul Soon Yong ),( Chien Ngoc Nguyen ) 영남대학교 약품개발연구소 2016 영남대학교 약품개발연구소 연구업적집 Vol.26 No.-

Polyro.t-lactic-co-glycolic acid) (PLGA) nanoparticles with negative surface charge were reversed to positive by cationic surfactant-DDAB before being coated with an anionic polymer, hyaluronic acid, to improve their site-specific intracellular delivery against CD44 receptor overexpressing cancer cells. Incorporating artesunate (ART)-a promising anticancer drug into PLGA/HA nanoparticles, is expected not only to overcome its poor aqueous solubility and stability but also enhance the activities. The obtained particles were characterized by dynamic light scattering, zeta potential measurements, and transmission electron microscopy (TEM). Cancer cell internalization of the NPs was evaluated by flow cytometry and cytotoxicity of the NPs was tested by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. PLGA/HA nanoparticles showed greater extent of cellular uptake to SCC-7 and MCF-7 cells, indicating their affinity with CD44 receptor-mediated endocytosis. Almost 60 % of ART was released into the outer media after 48 h. In vitro fluorescence sorting demonstrated that PLGA/HA had highly efficient targeting and accumulation into CD44 receptor overexpression cells. The significant reduction in cell viability as well as greater induction of apoptosis suggested a potential in anticancer therapy of ART loaded PLGA/HA.

Development and Evaluation of Artesunate-Loaded Chitosan-Coated Lipid Nanocapsule as a potential Drug Delivery System Against Breast Cancer

( Tuan Hiep Tran ),( Tuan Duc Nguyen ),( Bijay Kumar Poudel ),( Hanh Thuy Nguyeon ),( Jong Oh Kim ),( Chul Soon Yong ),( Chien Ngoc Nguyen ) 영남대학교 약품개발연구소 2016 영남대학교 약품개발연구소 연구업적집 Vol.26 No.-

Artesunate (ART)-a well-known hydrophobic anti-malarial agent was incorporated in a polymer-lipid hybrid nanocolloidal system for anti-cancer therapeulic, The lipid negatively charged nanocmulsion was formulated by modified hot homogenization method then covered with positively charged chitosan via clectroslatic interaction to obtain chitosan-coated lipid nanocapsule (ART-CLN). Physical properties of the system were characterized in terms of size, charge morphology, drug loading capacity, and physicca stale, In addition, anti-cancer activities were confirmed by conductiong MTT assay for ART and ART-CLN, on different cancer cell lines. Obtained ART_CLN after coating chilosan revelated positive charge (13.2±0.87 mV), small particle size (160.9±3.5 nm), and spherical shape. High drug entrapment cfficiency (95.49±1.13%) and sustaubed rekease pattern were obscrved. Moreover, the good cellular uptake was recorded by flow cytomctry as well as confocal image. Finally, ART-CLN Exhibited stronger anti-cancer activity than free ART on breast cancer cell lines (MCF-7, MDA-MB-231). These results suggested that by lading ART into lipid core of polymer lipid hybrid carrier, the activity and physical stability of ART can be significantly increased for cancer chemotherapy.