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Hao-tong Zhou,Chang-qing Liu,Gui-he Wang,Kai Kang,Yu-hong Liu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.5
Given the hazards caused by drilling ground collapse (DGC) due to groundwater flow in the processes of geotechnical engineering investigation, a coupled computational fluid dynamics and discrete element method (CFD-DEM) method is adopted to numerically simulate the development of hazards. An improved coupling program is employed to realize the two-way coupling between open-source CFD code OpenFOAM and commercial DEM software PFC3D. The coupling program allows complex meshes generated by ANSYS ICEM to be imported into PFC3D. The feasibility and accuracy of the CFD-DEM method are first verified by simulating a single spherical particle settling in hydrostatic water and the formation of the repose angle of sandpiles. Then, this method is adopted to investigate the patterns of stratum deformation and foundation loss, typical particle flow processes, and characteristics of drilling rig toppling. Finally, measures for prevention of DGC induced by groundwater flow are discussed in detail. Two typical strata, including a water-rich sand stratum and a water-rich sand-clay compound stratum, are considered. The research results show that for the water-rich sand stratum, DGC induces a “bowl”-shaped settlement trough, and the maximum value of ground surface settlement is proportional to the foundation loss rate. For the water-rich sand-clay compound stratum, a “jar”-shaped settlement trough is created. Four typical particle flow processes are involved in DGC. The drilling rig topples toward the center of the settlement trough. The maximum displacement appears at the top of the tower and has an approximate linear correlation with the groundwater flow velocity. The measures and methods of DGC prevention are also summarized in detail. The results of this research provide a reference for hazard prevention and delicacy control of DGC induced by groundwater flow.
강유정(Yu-Jung Kang),Chen Hao,안진우(Jin-WooAhn) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
The paper presents the componet parts and their models for the switched reluctance motor drive system with the angle position-current chopping control and with the fixed angle pulse width modulation control. The calculation of the parameters and the simulated models based on the MATHLAB SIMULiNK software package are introduced by a four-phase 8/6 structure prototype with the four-phase asymmetric bridge power converter. The simulation of the prototype in the course of starting is made by the simulated models at the different control strategies and speeds.
Shih-kang Lin,Hao-miao Chang,Cheng-liang Cho,Yu-chen Liu,Yi-kai Kuo 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4
Three-dimensional (3D) integrated circuits (ICs) are the most important packaging technology for next-generation semiconductors. Cu-to-Cu throughsilicon via interconnections with micro-bumps are key components in the fabrication of 3D ICs. However, significant reliability concerns have been raised due to the formation of brittle intermetallic compounds in the entire 3D IC joints. This study proposes a Ga-based Cu-to-Cu bonding technology with Pt under bump metallurgy (UBM). A systematic analysis of reactive wetting between Ga solders and polycrystalline, single-crystalline, and Ptcoated Cu substrates was conducted. Pt UBM as a wetting layer was identified to be a key component for Ga-based Cu-to-Cu bonding. Pt-coated Cu substrates were bonded using Ga solders with various Ga-to-Pt ratios (n) at 300°C. When n ≥ 4, the Cu/Pt/Ga/Pt/Cu interface evolves to Cu/facecentered cubic (fcc)/γ1-Cu9Ga4/fcc/Cu, Cu/fcc/γ1-Cu9Ga4 + Ga7Pt3/fcc/Cu, and finally Cu/fcc + Ga7Pt3/Cu structures. The desired ductile solid solution joint formed with discrete Ga7Pt3 precipitates. When n ≤ 1, a Cu/Ga7Pt3/Cu joint formed without Cu actively participating in the reactions. The reaction mechanism and microstructure evolution were elaborated with the aid of CALPHAD thermodynamic modeling.
Li Changchao,Kang Zhongjian,Yu Hongguo,Wang Hao,Li Kaiji 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.5
Aiming at the energy optimization problem of multi-microgrid system, a energy optimization method of multi-microgrid system is proposed based on cooperative game theory in this paper. Firstly, taking economic cost as the objective function, a cooperative game model of multi-microgrid system is established based on the cooperative game theory. Secondly, taking the electricity price and power trading volume between micro grids as strategies and the fi nal operation cost or revenue of each micro grid as the benefi t function of the game to conduct the cooperative game under the price constraint agreement and benefi t compromise agreement. The electricity price and trading power between micro grids are obtained to achieve optimization of multi-level microgrids. Finally, the optimization method is simulated to prove the feasibility. The simulation results show that the method can eff ectively achieve the energy optimal scheduling of multi-microgrid system.
Research on Optimization Method of Home Energy Management System in Smart Grid
Li Changchao,Kang Zhongjian,Yu Hongguo,Wang Hao,Li Kaiji 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.5
In order to save users' electricity costs, this paper proposes an optimized management method for the home energy management system. Firstly, a household power grid is constructed that include photovoltaic system, energy storage system, power adjustable load, unscheduled load, and time adjustable load model. Secondly, in order to obtain a solution that can both rationalize the allocation of household load working time and minimize household electricity costs, a double objective function is defi ned. Considering the real-time price of the power grid, the optimization strategy for household energy management is formulated. Finally, simulating the daily electricity consumption of households to verify that the optimized management method of the household energy management system can eff ectively reduce users' electricity costs.
Yi-Chu Nie,Hao Wu,Pei-Bo Li,Yu-Long Luo,Kang Long,Li-Ming Xie,Jian-Gang Shen,Wei-Wei Su 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.10
Naringin, a well-known flavanone glycoside of grapefruit and citrus fruits, was found to be as an effective anti-inflammatory compound in our previous lipopolysaccharide-induced acute lung injury mouse model via blockading activity of nuclear factor κB. The current study sought to explore the anti-inflammatory effects of naringin on chronic pulmonary neutrophilic inflammation in cigarette smoke (CS)-induced rats. Seventy Sprague-Dawley rats were randomly divided into seven groups to study the effects of CS with or without various concentrations of naringin or saline for 8 weeks. The results revealed that naringin supplementation at 20, 40, and 80 mg/kg significantly increased body weight of CS-induced rats as compared to that in the CS group. Moreover, naringin of 20, 40, and 80 mg/kg prevented CS-induced infiltration of neutrophils and activation of myeloperoxidase and matrix metalloproteinase-9, in parallel with suppression of the release of cytokines, such as tumor necrosis factor-α and interleukin-8 (IL-8). IL-10 in bronchoalveolar lavage fluid was significantly suppressed after CS exposure, but dose dependently elevated by naringin. The results from hematoxylin and eosin staining revealed that naringin dose dependently reduced CS-induced infiltration of inflammatory cells, thickening of the bronchial wall, and expansion of average alveolar airspace. In conclusion, our data suggest that naringin is an effective anti-inflammatory compound for attenuating chronic pulmonary neutrophilic inflammation in CS-induced rats.