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하수슬러지 경량골재의 플라이애시에 의한 점토 대체 가능성 평가
퐁트루 쿠엔,김득모,문경주,소양섭 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)
This study was carried out according to two series of experiments. The first series of experiment, green aggregates, which is a mixture of sewage sludge and clay, with different content of sewage sludge (up to 80 wt%), were prepared and the second series of experiments belongs to green aggregates contain amount of fly ash up to 20wt% in replacement of clay. Then they were burned in different soak temperatures from 1200'C to 1280'C with fixed soak time and fixed heating rate at 5 minutes and 20°C/min respectively in order to produce lightweight aggregate (L W A). Data of both experiment series were generated to evaluate the quality of L W A as well as the relationship between burning condition and product's quality. As the result, by adding clay and fly ash to sewage sludge, LWA used for non-structural concrete is successfully manufactured with relatively high content of sewage sludge (60-80wt%). Generally, the quality of LWA containing fly ash is better than that of LWA containing only clay. Especially, the strength of L W A is much improved when fly ash is added and the quality of aggregate contains fly ash is comparable with that of Spain aggregate. The parameters used for controlling the quality of L W A such as soak temperature as well as its chemical composition show directly proportional influence in a narrow limit. Thus, additive studies should be carried out in order to successfully produce LWA in industrial scale.
Trong Hoa Pham,Dinh Tu Nguyen,Jürgen Weber 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1
Internal gear motor and pump is the typical rotating machine which operates in hybrid regime of lubrication. Calculation of the pressure distribution in the oil-lubrication film is the fundamental issue for determination of the upper and lower speed limit as well as analysis of the stability phenomenon of internal gear motor and pump. However, the simultaneously existence problem of hydrodynamic and hydrostatic pressure in case of hybrid regime is a challenge for calculation. This paper introduces an approach for calculation of 1D hybrid pressure distribution. The Reynolds equation with appropriate boundary condition is solved to obtain 2D hydrodynamic pressure distribution by using the finite difference method (FDM). The resistance network model (RNM) is used to predict the 1D hydrostatic pressure profile. Based on the hydrostatic and hydrodynamic pressure, the 1D total pressure profile can be retrieved. The CFD simulation has been performed to obtain the hydrostatic pressure profile and then compare to the hydrostatic pressure distribution by using RNM. A test rig has been designed to measure the oil-film pressure at five different points over the circumferential direction. Results pointed out that the numerical calculation agree well with the experimental results, particularly at high values of the working pressure.
Spontaneous dissections of multiple visceral arteries
Trong Binh Le,Yong Sun Jeon,Kee Chun Hong,Soon Gu Cho,Keun-Myoung Park 대한외과학회 2017 Annals of Surgical Treatment and Research(ASRT) Vol.92 No.4
Spontaneous dissections of visceral arteries without aortic involvement are very rare. The etiologies of these entities are unclear and their clinical managements remain controversial. We report a case of spontaneous multiple dissections affecting 4 visceral arteries including the superior mesenteric artery, the celiac artery and the bilateral renal arteries. The patient was managed conservatively and endovascularly. The clinical manifestation markedly improved and laboratory tests returned to normal limits within 1 week. The regular follow-up suggested a good clinical and radiological outcome until 84 months.
Trong-Ha Nguyen,Ngoc-Long Tran,Duy-Duan Nguyen 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.4
The web tapered I-section steel (WTIS) columns have been widely used in civil and industrial steel structures. However, the existing theoretical and empirical equations demonstrate a signifi cant discrepancy in estimating the critical axial load of the WTIS columns. This study aims to develop eff ective artifi cial neural networks (ANNs) for predicting the critical buckling load of the WTIS columns. A database of 269 fi nite element models of WTIS columns was generated, after verifying with experimental results, to develop the ANN model. The results of the proposed ANN model were also compared with those of existing formulas, highlighting that the ANN model in this study predicts the critical buckling load of the WTIS columns more accurately than the existing formulas. Moreover, the infl uences of input parameters on the critical buckling load of the WTIS columns were thoroughly investigated. An ANN-based formula, which considers input variables, was thereafter proposed to estimate the critical buckling load of the WTIS columns. Additionally, a graphical user interface tool has been developed for simplifying the design practice of the WTIS columns.
Trong Duy Nguyen,Gilbert Foo Hock Beng,King-Jet Tseng,Don Mahinda Vilathgamuwa,Xinan Zhang 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.5
This paper presents the modeling and position-sensorless vector control of a dual-airgap axial flux permanent magnet (AFPM) machine optimized for use in flywheel energy storage system (FESS) applications. The proposed AFPM machine has two sets of three-phase stator windings but requires only a single power converter to control both the electromagnetic torque and the axial levitation force. The proper controllability of the latter is crucial as it can be utilized to minimize the vertical bearing stress to improve the efficiency of the FESS. The method for controlling both the speed and axial displacement of the machine is discussed. An inherent speed sensorless observer is also proposed for speed estimation. The proposed observer eliminates the rotary encoder, which in turn reduces the overall weight and cost of the system while improving its reliability. The effectiveness of the proposed control scheme has been verified by simulations and experiments on a prototype machine.
Simultaneous Synthesis of Anatase Colloidal and Multiple-branched Rutile TiO2 Nanostructures
Trong Tung Nguyen,Xuan-Dung Mai,Ngoc Huyen Duong 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.3
Facile synthesis of titanium dioxide (TiO2) nanostructures with controllability over their cystallinity, dimensions, and shape is in demand for diverse optoelectronic applications. Anatase colloidal particles and precipitates of rutile bundles were synthesized simultaneously using HCl catalyzed sol–gel process with titanium tetrachloride as Ti precursor. The crystallinity and the morphology of these two separable TiO2 phases were studied by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The results show that by varying HCl concentration during synthesis, dimensions of colloidal anatase can be tuned from spherical particles with a diameter of 2–5 nm to nanorods of dimension of 4 nm (width) × 14 nm (length). The rutile bundles whose size increased with aging time consisted of multiple branches with elongation along c-axis. Both anatase nanorods and rutile bundles can be applied as highly efficient photocatalysts or electron conduits.