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Identification and Controller Design of a Ship for Berthing System Design
V. P. Bui,Y. B. Kim,J. H. Yang,H. Y. Kang 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.6
In this paper, we describe the ship maneuvering method for berthing automatically. The system identification technique (SI) is carried out on the measured data, with the intention of evaluating the hydrodynamic coefficient of the ship model. It is derived from the horizontal motion equation of ship. The performance of the controller is also analyzed to robustness the present of wind, wave disturbance, also model uncertainties. The simulated and experimental results will be present to estimate the potential accuracy of both identification and controller.
Super-amphiphilic surface of nano silica/polyurethane hybrid coated PET film via a plasma treatment
Bui, V.T.,Liu, X.,Ko, S.H.,Choi, H.S. Academic Press 2015 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.453 No.-
This study first reports the fabrication of a super-amphiphilic surface using PET films with a silica-polyurethane hybrid top-coat layer through a non-thermal, one-atmospheric-pressure plasma treatment. This surface displays contact angle close to zero with both aqueous and oily liquids, which has attracted enormous attention for a wide-range of practical applications. We systematically investigated the influence of the plasma treatment time on the wetting behavior of the silica-polyurethane coated PET surface. The changes in morphology and chemical composition of PET surfaces before and after a plasma treatment were analyzed. In order to gain an insight into the formation of a super-amphiphilic PET surface and optimize the conditions under which super-amphiphilicity can be realized, we used a hemi-wicking action as a theoretical model and experimentally verified it through determining the critical angle. We also proposed a guide for designing a nano-sphere patterned PDMS surface which can generate super-wetting properties after a plasma treatment.
Mechanical performances of concrete beams with hybrid usage of steel and FRP tension reinforcement
Linh V. H. Bui,Boonchai Stitmannaithum,Tamon Ueda 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.4
Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and especially in corrosive environments to improve the durability of concrete structures. However, FRPs have a low modulus of elasticity and a linear elastic behavior up to rupture, thus reinforced concrete (RC) components with such materials would exhibit a less ductility in comparison with steel reinforcement at the similar members. There were several studies showed the behavior of concrete beams with the hybrid combination of steel and FRP longitudinal reinforcement by adopting the experimental and numerical programs. The current study presents a numerical and analytical investigation based on the data of previous researches. Three-dimensional (3D) finite element (FE) models of beams by using ANSYS are built and investigated. In addition, this study also discusses on the design methods for hybrid FRP-steel beams in terms of ultimate moment capacity, load-deflection response, crack width, and ductility. The effects of the reinforcement ratio, concrete compressive strength, arrangement of reinforcement, and the length of FRP bars on the mechanical performance of hybrid beams are considered as a parametric study by means of FE method. The results obtained from this study are compared and verified with the experimental and numerical data of the literature. This study provides insight into the mechanical performances of hybrid FRP-steel RC beams, builds the reliable FE models which can be used to predict the structural behavior of hybrid RC beams, offers a rational design method together with an useful database to evaluate the ductility for concrete beams with the combination of FRP and steel reinforcement, and motivates the further development in the future research by applying parametric study.
Anti-inflammatory Triterpenoid Saponins from the Stem Bark of <i>Kalopanax pictus</i>
Quang, Tran H.,Ngan, Nguyen T. T.,Minh, Chau V.,Kiem, Phan V.,Nhiem, Nguyen X.,Tai, Bui H.,Thao, Nguyen P.,Tung, Nguyen H.,Song, Seok B.,Kim, Young H. American Chemical Society and American Society of 2011 Journal of natural products Vol.74 No.9
<P>Five new compounds, 16,23,29-trihydroxy-3-oxo-olean-12-en-28-oic acid (<B>1</B>), 4,23,29-trihydroxy-3,4-<I>seco</I>-olean-12-en-3-oate-28-oic acid (<B>2</B>), 3β,6β,23-trihydroxyolean-12-en-28-oic acid 28-<I>O</I>-β-<SMALL>d</SMALL>-glucopyranoside (<B>3</B>), 3-<I>O</I>-[2,3-di<I>-O</I>-acetyl-α-<SMALL>l</SMALL>-arabinopyranosyl]hederagenin 28-<I>O</I>-α-<SMALL>l</SMALL>-rhamnopyranosyl-(1→4)-β-<SMALL>d</SMALL>-glucopyranosyl-(1→6)-β-<SMALL>d</SMALL>-glucopyranoside (<B>4</B>), and 3-<I>O</I>-[3,4-di-<I>O</I>-acetyl-α-<SMALL>l</SMALL>-arabinopyranosyl]hederagenin 28-<I>O</I>-α-<SMALL>l</SMALL>-rhamnopyranosyl-(1→4)-β-<SMALL>d</SMALL>-glucopyranosyl-(1→6)-β-<SMALL>d</SMALL>-glucopyranoside (<B>5</B>), as well as 10 known compounds (<B>6</B>–<B>15</B>), were isolated from the stem bark of <I>Kalopanax pictus</I>. Compounds <B>1</B>–<B>5</B> and <B>7</B>–<B>14</B> inhibited TNFα-induced NF-κB transcriptional activity in HepG2 cells in a dose-dependent manner, with IC<SUB>50</SUB> values ranging from 0.6<B></B>to 16.4 μM. Furthermore, the transcriptional inhibitory function of these compounds was confirmed on the basis of decreases in COX-2 and iNOS gene expression in HepG2 cells. The structure–activity relationship of the compounds with respect to anti-inflammatory activity is also discussed.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jnprdf/2011/jnprdf.2011.74.issue-9/np200382s/production/images/medium/np-2011-00382s_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/np200382s'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/np200382s'>ACS Electronic Supporting Info</A></P>
Connection stiffness reduction analysis in steel bridge via deep CNN and modal experimental data
Hung V. Dang,Mohsin Raza,H. Tran-Ngoc,T. Bui-Tien,Huan X. Nguyen 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.4
This study devises a novel approach, namely quadruple 1D convolutional neural network, for detecting connection stiffness reduction in steel truss bridge structure using experimental and numerical modal data. The method is developed based on expertise in two domains: firstly, in Structural Health Monitoring, the mode shapes and its high-order derivatives, including second, third, and fourth derivatives, are accurate indicators in assessing damages. Secondly, in the Machine Learning literature, the deep convolutional neural networks are able to extract relevant features from input data, then perform classification tasks with high accuracy and reduced time complexity. The efficacy and effectiveness of the present method are supported through an extensive case study with the railway Nam O bridge. It delivers highly accurate results in assessing damage localization and damage severity for single as well as multiple damage scenarios. In addition, the robustness of this method is tested with the presence of white noise reflecting unavoidable uncertainties in signal processing and modeling in reality. The proposed approach is able to provide stable results with data corrupted by noise up to 10%.
Numerical and experimental approach on energy dissipation in nano colloidal damper
구태완,S. B. Jeon,V. H. Bui,송우진,M. S. Park,강범수 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.10
Mechanical damping systems have been widely used to various mechanical structures and systems, and are mainly hydraulic and pneumatic devices nowadays. New damping system such as nano colloidal damper (NCD) is complementary to the hydraulic one, having a cylinder-piston-orifice structure. This study includes numerical and experimental investigation about energy dissipation of NCD by using porous silica particles. In numerical approach, the dissipated energy was obtained between compression and relaxation processes for porous silica particle in NCD according to the capillary tube theory. Furthermore, for colloidal damper, the hydraulic oil was replaced by a colloidal suspension that was consisted of a nano-porous matrix with controlled architecture and a lyophobic fluid. NCD test rig and the measuring technique of the hysteresis were described in this study. Performance of the energy dissipation between numerical and experimental results was investigated and compared. As a result, the proposed NCD was proved to efficiently dissipate the mechanical energy.