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Van Khoi Pham(팜반코이),Changhoon Lee(이창훈),Van Nghi Vu(부반니) 한국해안해양공학회 2019 한국해안해양공학회 논문집 Vol.31 No.4
산사태의 시간에 따른 전파를 모의하기 위해서 천수방정식을 사용하여 산사태 수치모형을 개발하였다. 하천 및 해양에서의 산사태에 모두 해석이 가능하도록 (b, s) 좌표로 표현된 천수방정식을 개발하였다. 산사태에서 발생하는 수치적인 불연속성을 극복하기 위해서 HLL approximate Riemann solver와 total variation diminishing (TVD) limiter를 사용한 유한체적법을 사용하였다. 댐파괴 흐름와 토석류의 각 경우에 수치해석을 수행한 결과를 해석해와 실험자료와 비교를 하였다. 그 결과 서로 유사함을 확인되었다. 본 모형을 사용하여 해상 산사태와 해저 산사태를 성공적으로 모의하였다. 해저 산사태에 비해 해상 산사태의 전파속도가 더 빠르고, 바닥경사가 급할수록 또는 거칠기가 작을수록 산사태 전파속도가 더 빨라짐을 확인하였다. A model of landslides is developed using the shallow water equations to simulate time-dependent performance of landslides. The shallow water equations are derived using the (b, s) coordinate system which can be applied in both river and ocean. The finite volume scheme employing the HLL approximate Riemann solver and the total variation diminishing (TVD) limiter is applied to deal with the numerical discontinuities occurring in landslides. For dam-break water flow and debris flow, numerical results are compared with analytical solutions and experimental data and good agreements are observed. The developed landslide model is successfully applied to predict subaerial and submarine landslides. It is found that the subaerial landslide propagates faster than the submarine landslide and the speed of propagation becomes faster with steeper bottom slope and less bottom roughness.
Phung Bao Ngoc,Nguyen Khoi Viet,Hoang Van Hoa,Nguyen Ngoc Trang,Le Thi Thuy Lien,Pham Minh Thong,Vu Dang Luu 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.2
Left pulmonary artery sling (LPAS) is a rare congenital anomaly in which the left pulmonary artery (LPA) originates from the posterior aspect of the right pulmonary artery and courses between the trachea and esophagus to reach the left lung. This anomaly causes distal tracheal and/or right main stem bronchus compression. Most LPAS cases are associated with early symptom onset, around 2 month-old, and have severe respiratory distress within the first year of life. There are two major types of LPAS based on the location of LPA and abnormal bronchial branching. The diagnosis can be made by using various imaging modalities. Herein, we present the imaging characteristics on multidetector computed tomography of 5 LPAS cases with respiratory distress (2 months to 12 months).
Bui Hung Thang,Pham Van Trinh,Le Dinh Quang,Nguyen Thi Huong,Phan Hong Khoi,Phan Ngoc Minh 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.3
Carbon nanotubes (CNTs) are some of the most valuable materials with high thermal conductivity. The thermal conductivity of individual multiwalled carbon nanotubes (MWCNTs) grown byusing chemical vapor deposition is 600 ± 100 Wm−1K−1 compared with the thermal conductivity419 Wm−1K−1 of Ag. Carbon-nanotube-based liquids – a new class of nanomaterials, have shownmany interesting properties and distinctive features offering potential in heat dissipation applicationsfor electronic devices, such as computer microprocessor, high power LED, etc. In this work,a multiwalled carbon-nanotube-based liquid was made of well-dispersed hydroxyl-functional multiwalledcarbon nanotubes (MWCNT-OH) in ethylene glycol (EG)/distilled water (DW) solutionsby using Tween-80 surfactant and an ultrasonication method. The concentration of MWCNT-OHin EG/DW solutions ranged from 0.1 to 1.2 gram/liter. The dispersion of the MWCNT-OH-basedEG/DW solutions was evaluated by using a Zeta-Sizer analyzer. The MWCNT-OH-based EG/DWsolutions were used as coolants in the liquid cooling system for the Intel Core i5 processor. Thethermal dissipation efficiency and the thermal response of the system were evaluated by directlymeasuring the temperature of the micro-processor using the Core Temp software and the temperaturesensors built inside the micro-processor. The results confirmed the advantages of CNTs inthermal dissipation systems for computer processors and other high-power electronic devices.
Le Thi Thuy Lien,Nguyen Khoi Viet,Hoang Van Hoa,Phung Bao Ngoc,Nguyen Ngoc Trang,Vu Thi Kim Thoa,Nguyen Cong Tien,Phan Anh Phuong,Pham Minh Thong,Vu Dang Luu 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.2
Objective: To compare left ventricular (LV) function, ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), and regional wall motion analyzed in 256-slice dualsource coronary CT angiography (DSCT) with 2D transthoracic echocardiography (TTE). Materials and Methods: One hundred twelve patients suspected of coronary artery disease underwent DSCT and 2D-TTE within one week for LVEF, EDV, and ESV. The correlation between DSCT and 2D-TTE measurements was analyzed through linear regression and Bland- Altman analysis. Regional wall motion was visually scored with a 3-point scale (1, normal; 2, hypokinesia; 3, dysphagia, akinesia). Results: Average LVEF at 66.45%±1.27% (range 23%–85%) as determined on DSCT compared with 66.09%±1.01% (range 25%–84%) on 2D-TTE. LVEF exhibited a good correlation between DSCT and 2D-TTE (r=0.715; p<0.001). Good correlations between DSCT and 2D-TTE were demonstrated for LVEDV (r=0.732; p<0.001) and LVESV (r=0.841; p<0.001). Mean differences (±SD) of 1.78±24.10 mL (p<0.05) and 0.77±13.70 mL (p<0.05) were observed between DSCT and 2D-TTE for LVEDV and LVESV, respectively. LVEF was slightly overestimated with DSCT (0.52%±9.59%; p<0.05). Although the LVEF values calculated by DSCT and 2D-TTE were similar, EDV and ESV from DSCT were statistically higher than those from 2D-TTE (p<0.05). Agreement between DSCT and 2D-TTE in regional wall motion was 96.4%, κ=0.840. Conclusion: DSCT can provide comparable results to those using 2D-TTE for LV function (EF, EDV, and ESV) and regional wall motion assessment in a heterogeneous population.
Raman spectroscopy of Cu doping in Zn<sub>1−x</sub>Co<sub>x</sub>O diluted magnetic semiconductor
Hoang, Luc Huy,Hien, Nguyen Thi Minh,Hai, Nguyen Hoang,Hai, Pham Van,Khoi, Nguyen The,Yang, In-Sang John Wiley Sons, Ltd. 2009 JOURNAL OF RAMAN SPECTROSCOPY - Vol.40 No.11
<P>The room-temperature ferromagnetism and the Raman spectroscopy of the Cu-doped Zn<SUB>1−x</SUB>Co<SUB>x</SUB>O powders prepared by the sol–gel method are reported. The x-ray diffraction (XRD) data confirmed that the wurtzite structure of ZnO is maintained for ZnO doped with Co below 10 at%. The magnetization–field curves measured at room temperature demonstrated that all Co-doped ZnO powders were paramagnetic. Ferromagnetic ordering is observed for the samples doped with Cu in Zn<SUB>0.98</SUB>Co<SUB>0.02</SUB>O and strongly depends on the concentration of Cu. The relative strength of the second-order LO peak to the first-order one in the Raman spectra, which is related to the carrier concentration, of the Cu-doped Zn<SUB>0.98</SUB>Co<SUB>0.02</SUB>O powder is strongly correlated with the saturation magnetic moment of the system. This seems to be in favor of the Ruderman-Kittel-Kasuya-Yosida (RKKY) or double exchange mechanism of the ferromagnetism in this system. Copyright © 2009 John Wiley & Sons, Ltd.</P> <B>Graphic Abstract</B> <P>The room-temperature ferromagnetism and the Raman spectroscopy data of Cu-doped Zn<SUB>1−x</SUB>Co<SUB>x</SUB>O powders prepared by the sol–gel method are reported. The relative strength of the second-order LO peak to the first-order one in the Raman spectra, which is related to the carrier concentration, of Cu-doped Zn<SUB>0.98</SUB>Co<SUB>0.02</SUB>O powder is strongly correlated with the saturation magnetic moment of the system. <img src='wiley_img/03770486-2009-40-11-JRS2295-gra001.gif' alt='wiley_img/03770486-2009-40-11-JRS2295-gra001'> </P>