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Do Minh Duc,Nguyen Hong Hai,Pham Quang 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.3
Computational fluid dynamic modeling of a continuous rheo-casting technology was conducted, consistent with the manufacturing of 3 -thin plates made of aluminum alloy A356. The A numerical simulation on of the stabilizing time of the material crystallization was carried out using the ANSYS FLUENT code. Solidification and melting models were simulated with heat transfer and solid-liquid phase transformation involving the latent heat of crystallization were simulated. The calculated temperature distribution and the evolution of cooling rate through the material were examined and used to clarify their influence on microstructure, and further investigated with hardness testing. The thickness of the mushy zone was determined for the steady conduction solution of the continuous rheo-casting process.
Optimal workpiece positioning in flexible fixtures for thin-walled components
Do, Minh Duc,Son, Younghoon,Choi, Hae-Jin Elsevier 2018 Computer aided design Vol.95 No.-
<P><B>Abstract</B></P> <P>Flexible fixtures are finding widespread use in manufacturing processes of thin-walled components in the automotive and aerospace industries. Owing to its reconfigurability, a flexible fixture can take different layouts depending on the workpiece geometry and location. By finding the appropriate workpiece location, the deformation of workpieces under machining forces and their own weights can be reduced, hence increasing the quality of the final products. In this paper, we introduce a novel method for optimum workpiece positioning in rod type flexible fixtures for thin-walled components. First, the geometry of the workpiece is extracted from its CAD model. Second, a geometry-based method is proposed to find the optimal location of the workpiece relative to the fixture system. A composition of homogeneous transformations is performed to maximize the workpiece support capacity, initially place the workpiece in the fixture region, and maximize the number of active fixture elements (fixels). Third, the result is verified and visualized in a fixture verification module. An aircraft body panel is employed as an example to test the performance of the proposed method. Finally, conclusions and future studies are discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We proposed a novel workpiece positioning method of flexible fixtures. </LI> <LI> The workpiece positioning was reduced to 2D polygon problems. </LI> <LI> The number of supports was maximized by optimizing a point-in-polygon problem. </LI> <LI> The cutting-tool fixture interference was avoided automatically. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Nguyen Van Hieu,Le Thi Ngoc Loan,Nguyen Duc Khoang,Nguyen Tuan Minh,Do Thanh Viet,Do Cong Minh,Tran Trung,Nguyen Duc Chien 한국물리학회 2010 Current Applied Physics Vol.10 No.2
In this paper, a very simple procedure was presented for the reproducible synthesis of large-area SnO2nanowires (NWs) on a silicon substrate by evaporating Sn powders at temperatures of 700, 750, and 800 ℃. As-obtained SnO2 NWs were characterized by field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. They revealed that the morphology of the NWs is affected by growth temperature and the SnO2 NWs are single-crystalline tetragonal. The band gap of the NWs is in the range of 4.2–4.3 eV as determined from UV/visible absorption. The NWs show stable photoluminescence with an emission peak centered at around 620 nm at room-temperature. The sensors fabricated from the SnO2 NWs synthesized at 700 ℃ exhibited good response to LPG (liquefied petroleum gas) at an operating temperature of 400 ℃.
A Single-Phase Buck-Boost Derived Common-Ground Inverter
Duc-Tri Do,Vinh-Thanh Tran,Tuyet-Dan Bui Thi,Ngoc-Han Vuong Thi,Minh-Khai Nguyen 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
This paper presents a new topology for the single-phase buck-boost derived common-ground inverter (1PBBD- CGI). The 1P-BBD-CGI uses two extra switching devices besides conventional inverting buck-boost DC-DC converter to feature DC-AC operation. In this topology, the negative point of output load is directly connected to the ground of the DC input source. Hence, this topology can completely eliminate leakage current. Furthermore, having a lower component voltage rating and using film-capacitor make the proposed inverter have higher efficiency and reliability than other previous common-ground inverters. The proposed 1P-CDCGI has been verified by simulation and experimental results with the help of PLECS software and 300-W laboratory prototype.
Do Ngoc Khue,Tran Dai Lam,Nguyen Van Chat,Vu Quang Bach,Do Binh Minh,Vu Duc Loi,Nguyen Van Anh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Here we report the study on the utilization of several advanced oxidation processes such as electro-oxidation and Fenton process in simultaneous treatment of two nitramine explosives: 2,4,6-trinitrophenyl-N-metylnitramine (Tetryl) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The preliminary tests indicated that the electrolytic method using a TiO2/IrO2/RuO2-coated electrode could rapidly degrade Tetryl but not RDX. While the addition of certain amount of H2O2 induced an increase of Tetryl degradation yield but had insignificant effect on RDX decomposition, the use of Fenton’s reagent showed an enhanced efficiency in degradation of both nitramines. It can be concluded that among tested processes, Fenton process is the most effective for treatment of nitramine-containing wastewaters.
Introduction of construction condition in Vietnam
( Ha Minh ),( Le Nguyen Giap ),( Do Thi Ngoc Chau ),( Do Nhu Duc ) 대한지질공학회 2014 대한지질공학회 학술발표회논문집 Vol.2014 No.1
This paper was conducted to evaluate the status of construction and infrastructure works in Vietnam. The approach included literature reviews to identify deterioration with site inspections and personal interviews to ascertain their validity. Results showed on overall picture of construction works in current condition, analyzed their main causes, and recommended the possible ways to improve the situation of construction works. Further, the paper provided information on policies and status of construction market in Vietnam so that Korean corporations would have a general view on Vietnamese construction industry at present