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Nguyen Duc Anh,Pham Van Thanh,Doan Tu Lap,Nguyen Tuan Khai,Tran Van An,Tran Duc Tan,Nguyen Huu An,Dang Nhu Dinh 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.2
Forest fires inflict great losses of human lives and serious damages to ecological systems. Hence, numerous fire detection methods have been proposed, one of which is fire detection based on sensors. However, these methods reveal several limitations when applied in large spaces like forests such as high cost, high level of false alarm, limited battery capacity, and other problems. In this research, we propose a novel forest fire detection method based on image processing and correlation coefficient. Firstly, two fire detection conditions are applied in RGB color space to distinguish between fire pixels and the background. Secondly, the image is converted from RGB to YCbCr color space with two fire detection conditions being applied in this color space. Finally, the correlation coefficient is used to distinguish between fires and objects with fire-like colors. Our proposed algorithm is tested and evaluated on eleven fire and non-fire videos collected from the internet and achieves up to 95.87% and 97.89% of F-score and accuracy respectively in performance evaluation.
An Efficient Design of 2.45/5.8 GHz Dual-Band Rectifier for Energy Harvesting Applications
Dang-An Nguyen(응웬당안),Chulhun Seo(서철헌) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10
In this paper, a novel topology is proposed for designing a compact and highly-efficiency shunt-diode rectifier for energy harvesting, operating concurrently at two widely-spaced frequency bands of 2.45 and 5.8 GHz. The structure deploys only three transmission line segments to realize dual impedance matching, which transforms diode impedances directly to the source of 50 Ohm and is analyzed in closed-form derivation. The simulation results based on HSMS2860 show that highest efficiency can be achieved simultaneously around 80% and 65% at 2.45 and 5.8 GHz, respectively with input power of 11dBm and load resistance of 600 Ohm.
Magnetocaloric Effect in Fe-Ni-Zr Alloys Prepared by Using the Rapidly-quenched Method
Nguyen Huy Dan,Nguyen Huu Duc,Tran Dang Thanh,Nguyen Hai Yen,Ngac An Bang,Do Thi Kim Anh,판더롱,유성초 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
Fe90−xNixZr10 (x = 0, 5, 10, 15, 20 and 25) ribbons with various thicknesses were prepared byusing a melt-spinning technique. The Curie temperature, TC, of the alloys dramatically decreasedfrom 960 K to room temperature at high quenching rates. When the alloys had an amorphousstructure, their TC strongly depended on the Ni concentration. The maximum entropy change,|Sm|max, with H = 12 kOe, of the alloys was around 1 J·kg−1K−1 at room temperature. Onthe other hand, the full width at half maximum the entropy-change peak was quite large, 85 K,which was suitable for applications in magnetic refrigerators at room temperature.
NGUYEN, Xuan Truong,NGUYEN, Thai Ha,DANG, Huynh Phuong,PHAM, Thi Lan Phuong,BUI, Thi Thanh,TRAN, Nhat Minh,HUYNH, Tri An,NGUYEN, Nam Phong Korea Distribution Science Association 2022 유통과학연구 Vol.20 No.2
Purpose: This study aims to identify factors affecting the adoption of e-commerce by household businesses in Vietnam's food and beverage industry. Research design, data and methodology: The integrated TAM and TOE frameworks and ten hypotheses were developed to test the relationship between relevant factors. A cross-sectional survey was conducted to collect valid data from 992 respondents who run F&B household businesses in Vietnam. Results: The empirical research results confirm all proposed hypotheses that e-commerce adoption is affected by the perceived usefulness, the perceived ease of use, vendor support partners, social expectancy, competitive pressure, subjective norm, and household resources. Meanwhile, technical readiness, environment readiness, and organization readiness are intermediate variables that influence the implementation of e-commerce in food and beverage distribution. Conclusions: The findings suggest effective orientations to foster the food and beverage e-trading practice for household businesses in developing countries. Accordingly, to encourage private household businesses to adopt e-commerce, it is necessary to focus on improving business resources, technology readiness, environment readiness, and organization readiness through raising awareness of usefulness, benefits, perceived ease of use, and increased support of vendor partners. Future research can focus on improving the efficiency of e-commerce applications in F&B distribution for both household businesses and larger-scale enterprises.
Xuan Truong NGUYEN,Thai Ha NGUYEN,Huynh Phuong DANG,Thi Lan Phuong PHAM,Thi Thanh BUI,Nhat Minh TRAN,Tri An HUYNH,Nam Phong NGUYEN 한국유통과학회 2022 유통과학연구 Vol.20 No.2
Purpose: This study aims to identify factors affecting the adoption of e-commerce by household businesses in Vietnam s food and beverage industry. Research design, data and methodology: The integrated TAM and TOE frameworks and ten hypotheses were developed to test the relationship between relevant factors. A cross-sectional survey was conducted to collect valid data from 992 respondents who run F&B household businesses in Vietnam. Results: The empirical research results confirm all proposed hypotheses that e-commerce adoption is affected by the perceived usefulness, the perceived ease of use, vendor support partners, social expectancy, competitive pressure, subjective norm, and household resources. Meanwhile, technical readiness, environment readiness, and organization readiness are intermediate variables that influence the implementation of e-commerce in food and beverage distribution. Conclusions: The findings suggest effective orientations to foster the food and beverage e-trading practice for household businesses in developing countries. Accordingly, to encourage private household businesses to adopt e-commerce, it is necessary to focus on improving business resources, technology readiness, environment readiness, and organization readiness through raising awareness of usefulness, benefits, perceived ease of use, and increased support of vendor partners. Future research can focus on improving the efficiency of e-commerce applications in F&B distribution for both household businesses and larger-scale enterprises.
Chi Linh, Dinh,Thi Ha, Nguyen,Huu Duc, Nguyen,Giang Nam, Le Huu,Bau, Le Viet,Manh An, Nguyen,Yu, Seong-Cho,Dang Thanh, Tran Elsevier 2018 PHYSICA B-CONDENSED MATTER - Vol.532 No.-
<P><B>Abstract</B></P> <P>In this work, we have investigated the magnetic properties and the magnetocaloric effect of La<SUB>0.7−x</SUB>Na<SUB>x</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB> compounds, which were prepared by a conventional solid-state reaction technique. The Rietveld refinement results suggested that the samples are single phase belonging to an orthorhombic structure (space group <I>Pnma</I>). Analyzing temperature dependence of magnetization <I>M</I>(<I>T</I>) revealed that the Curie temperature (<I>T</I> <SUB>C</SUB>) increases with increasing Na content (<I>x</I>). Their <I>T</I> <SUB>C</SUB> value is found to be 260–298K for <I>x</I>=0.0–0.1, respectively. Base on <I>M</I>(<I>T</I>) data measured at different applied magnetic fields (<I>H</I>), temperature dependence of magnetic entropy change Δ<I>S</I> <SUB>m</SUB>(<I>T</I>) data for all the samples was calculated by using a phenomenological model. In the vicinity of <I>T</I> <SUB>C,</SUB> -Δ<I>S</I> <SUB>m</SUB>(<I>T</I>) curve reaches a maximum value (denoted as |Δ<I>S</I> <SUB>max</SUB>|), which gradually increases with increasing <I>H</I>. Under 12kOe, the value of |Δ<I>S</I> <SUB>max</SUB>| is in a range of 1.47–5.19J/kgK corresponding to the relative cooling power RCP=57.12–75.88J/kg. Applied the universal master curve method for the magnetic entropy change, we concluded that Na-doped in La<SUB>0.7−x</SUB>Na<SUB>x</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB> compounds leads to modification the nature of the magnetic phase transition from the first- to the second-order.</P>
Thanh, Tran Dang,Linh, Dinh Chi,Yen, Pham Duc Huyen,Bau, Le Viet,Ky, Vu Hong,Wang, Zhihao,Piao, Hong-Guang,An, Nguyen Manh,Yu, Seong-Cho Elsevier 2018 PHYSICA B-CONDENSED MATTER - Vol.532 No.-
<P><B>Abstract</B></P> <P>In this work, we present a detailed study on the magnetic properties and the magnetocaloric effect (MCE) of La<SUB>1−x</SUB>K<SUB>x</SUB>MnO<SUB>3</SUB> compounds with <I>x</I>=0.05–0.2. Our results pointed out that the Curie temperature (<I>T</I> <SUB>C</SUB>) could be controlled easily from 213 to 306K by increasing K-doping concentration (<I>x</I>) from 0.05 to 0.2. In the paramagnetic region, the inverse of the susceptibility can be analyzed by using the Curie-Weiss law, <I>χ</I>(<I>T</I>)=<I>C</I>/(<I>T</I>−<I>θ</I>). The results have proved an existence of ferromagnetic clusters at temperatures above <I>T</I> <SUB>C</SUB>. Based on Banerjee's criteria, we also pointed out that the samples are the second-order phase transition materials. Their magnetic entropy change was calculated by using the Maxwell relation and a phenomenological model. Interestingly, the samples with <I>x</I>=0.1–0.2 exhibit a large MCE in a range of 282–306K, which are suitable for room-temperature magnetic refrigeration applications. The composites obtained from single phase samples (<I>x</I>=0.1–0.2) exhibit the high relative cooling power values in a wide temperature range. From the viewpoint of the refrigerant capacity, the composites formed out of La<SUB>1−x</SUB>K<SUB>x</SUB>MnO<SUB>3</SUB> will become more useful for magnetic refrigeration applications around room-temperature.</P>
Thanh C., Nguyen,An T., Dang,Khuong N.T., Tran Techno-Press 2022 Ocean systems engineering Vol.12 No.4
Annually, about 48-60% of sediment discharge of the Mekong River is delivered near the mouths of the Mekong River branches which is mostly coinciding with the southwest (SW) monsoon. This sediment budget in turn will be southwestwardly transported along the coast of the Mekong Delta (MD) during the northeast (NE) monsoon. Analysis of monsoonal changes in grain-size distribution (GSD) of surface sediment contributes to a better understanding of erosion and deposition processes along the MD. This study aims to figure out changes in GSD and sediment textures along the MD between SW and NE monsoons based on 183 surficial sediment samples collected along the MD during two field surveys carried-out in October 2016 and February-March 2017. Compared to the GSD during the SW and NE monsoon, the GSD along the MD changed significantly, especially in the estuary areas and along the coast of Bac Lieu and Ganh Hao. Whereas, in the west coast of the MD, GSD seem no changes between the two seasons. These changes in seabed sediment suggest that sediment with grain-sizes ranging from silt to fine sand can be transported during only a NE season.
Analysis of the Optimal Frequency Band for a Ballistic Missile Defense Radar System
Jeongho Park,Dong-Hui Lee,Chulhun Seo,Byoungho Cho,Dang-An Nguyen 한국전자파학회JEES 2018 Journal of Electromagnetic Engineering and Science Vol.18 No.4
In this paper, we consider the anti-attack procedure of a ballistic missile defense system (BMDS) at different operating frequencies at its phased-array radar station. The interception performance is measured in terms of lateral divert (LD), which denotes the minimum acceleration amount available in an interceptor to compensate for prediction error for a successful intercept. Dependence of the frequency on estimation accuracy that leads directly to prediction error is taken into account, in terms of angular measurement noises. The estimation extraction is performed by means of an extended Kalman filter (EKF), considering two typical re-entry trajectories of a non-maneuvering ballistic missile (BM). The simulation results show better performance at higher frequency for both tracking and intercepting aspects.