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Hai Le Xuan,Quoc-Dong Hoang,Soon Geul Lee,Dat Pham Xuan,Hoang Tran Viet,Minh Pham Van,Hung Pham Van,Hung Pham Viet,PHAM DUC TUAN,Duc Anh Nguyen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2
Ballbots, which have been studied for over ten years, are under-actuated mobile robots that operate using the inverted pendulum paradigm. Controlling a ballbot poses a number of challenges, including maintaining the stable upright posture from the ground in all directions and making sure it follows the desired trajectory. External factors such as a minor change in contact surface properties or fabrication errors can affect the system's stabilization and transfer capabilities. In this study, an adaptive hierarchical sliding mode control algorithm based on an artificial neural network is developed to make the ballbot robust to external factors. The use of the proposed controller ensures system stability despite uncertainties including friction, accidental centrifugal forces and gravity that occur when the ballbot follows the reference trajectory. The system stability is guaranteed on the basis of Lyapunov theory. Control efficiency and robot stability under system uncertainties are demonstrated by numerical simulation.
Effect of Saline Concentrations on Biological Nitrification in Batch Reactor
Young Joon Lee, Nguyen Viet Hoang, Nguyen Hong Khanh, Pham Tuan Linh, Gi Youn Kim 조선대학교 기초과학연구원 2011 조선자연과학논문집 Vol.4 No.2
Pham Tuan Linh2 and Gi Youn Kim This study was carried out on 4 batch reactors to determine the specific ammonium oxidizing rate (SAOR), specific nitrate forming rate (SNFR) and inhibitory degree of nitrifying activities with saline concentrations. Under salt free condition ammonia was consumed during the reaction period within 200 min. When the salt level increased to 10, 20 and 30 g NaClL-1 in reactor, ammonia depletion took 250, 300 and above 350 min, respectively. During concentration above 10 g NaClL-1, there was nitrite accumulation. Also, at 30 g NaClL-1 ammonia did not depleted and NO2 --N accumulated until the final reaction. Nitrate formation rates decreased with increasing salt concentration. SAOR and SNFR showed a decreasing trend as salinity concentrations were increased. The SAOR was reduced from 0.2 to 0.08 mg NH4+-N g-1VSS day-1 as the salt concentration increased from 0 to 30 g NaCLL-1. Similarly, the SNFR decreased from 0.26 kg NO3--N kg-1VSS day-1 at saline free to 0.1 kg NO3--N kg-1VSS day-1 at saline 30 g L-1. A severe inhibition of nitrifiers activity was observed at increased salt concentrations. The inhibition ratio of specific ammonium oxidation rates were 17, 47 and 60% on the reactor of 10, 20 and 30 g NaClL-1 added, respectively. The inhibition ratio of specific nitrate forming rates also were inhibited 30, 53 and 62% on the reactor of 10, 20 and 30 g NaClL-1 added, respectively. As the salinity concentrations increased from 0 to 30 mg NaClL-1, the average MLSS concentration increased from 1,245 to 1,735 mgL-1. The SS concentration of supernatant in reactor which settled about 30 minutes was not severely difference between concentration of salt free reactor and one of those high salt contained reactors
Viet Hoang Pham,Minh Hoang Trinh,Hyo-Sung Ahn 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
This paper studies formation control problem of multi-agent system whose interaction graph is acyclic generically persistent. We design a distributed control law for each agent to maintain its inter-agent distance constraints toward its neighbours. The designed control law uses only local relative position measurements and is proved to guarantee successfully for the convergences of agents to their desired equilibria in finite time, at which the formation of overall group of agents is congruent with a given desired one.
Travel Intention to Visit Tourism Destinations: A Perspective of Generation Z in Vietnam
NGUYEN, Viet Hoang,TRUONG, Thi Xuan Dao,PHAM, Huong Trang,TRAN, Duc Thanh,NGUYEN, Pham Hung Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2
The purpose of this research is to investigate the impacts of gen-Z's perception of consumer-generated content on social media on their travel intention with the mediating role of travel motivation push and pull. An online questionnaire survey of a total of 369 samples was conducted with the participation of gen Z in the most important cities across Vietnam. The model was analyzed using Structural Equation Modeling (SEM) using AMOS program 22 to investigate model relationships and all hypotheses are significant. The findings indicated that gen Z values the usefulness of social media and they use social media for knowledge-seeking (push factor), and this leads to their intention to visit a destination. SEM analysis also reveals that gen Z tends to use social media to find accessibility to any destinations and they are motivated highly with destinations that have clear and easy access, for example, no visa requirement or neighboring destinations. As the result, they have better intentions to visit these destinations. This research will help marketers, especially marketing specialists to gain a better understanding of gen Z, thus implement better marketing techniques to target gen Z.
A New Bearing-Only Navigation Law
Minh Hoang Trinh,Viet Hoang Pham,Phuong Huu Hoang,Jin-Hee Son,Hyo-Sung Ahn 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
This paper proposes a new bearing-only control law which can be used for autonomous navigation task. We firstly compare the proposed control law with a commonly used control law in the literature when the agent navigates with only one beacon. Second, we prove that if there are two or more beacons, the agent can almost globally asymptotically reaches the desired position under the proposed control law. Third, the proposed control law is then applied to a cooperative bearing-only navigation problem. Simulation result is given to support the mathematical analysis.
Unsupervised Outpatients Clustering: A Case Study in Avissawella Base Hospital, Sri Lanka
Hoang, Huu-Trung,Pham, Quoc-Viet,Kim, Jung Eon,Kim, Hoon,Park, Junseok,Hwang, Won-Joo Korea Multimedia Society 2019 멀티미디어학회논문지 Vol.22 No.4
Nowadays, Electronic Medical Record (EMR) has just implemented at few hospitals for Outpatient Department (OPD). OPD is the diversified data, it includes demographic and diseases of patient, so it need to be clustered in order to explore the hidden rules and the relationship of data types of patient's information. In this paper, we propose a novel approach for unsupervised clustering of patient's demographic and diseases in OPD. Firstly, we collect data from a hospital at OPD. Then, we preprocess and transform data by using powerful techniques such as standardization, label encoder, and categorical encoder. After obtaining transformed data, we use some strong experiments, techniques, and evaluation to select the best number of clusters and best clustering algorithm. In addition, we use some tests and measurements to analyze and evaluate cluster tendency, models, and algorithms. Finally, we obtain the results to analyze and discover new knowledge, meanings, and rules. Clusters that are found out in this research provide knowledge to medical managers and doctors. From these information, they can improve the patient management methods, patient arrangement methods, and doctor's ability. In addition, it is a reference for medical data scientist to mine OPD dataset.
Characterization of Ag-Doped p-Type SnO Thin Films Prepared by DC Magnetron Sputtering
Pham, Hoai Phuong,Thuy, Thanh Giang Le,Tran, Quang Trung,Nguyen, Hoang Hung,My Hoa, Huynh Tran,Thi Thu, Hoang,Cuong, Tran Viet Hindawi Limited 2017 Journal of nanomaterials Vol.2017 No.-
<P>Crystalline structure and optoelectrical properties of silver-doped tin monoxide thin films with different dopant concentrations prepared by DC magnetron sputtering are investigated. The X-ray diffraction patterns reveal that the tetragonal SnO phase exhibits preferred orientations along (101) and (110) planes. Our results indicate that replacing Sn<SUP>2+</SUP> in the SnO lattice with Ag<SUP>+</SUP> ions produces smaller-sized crystallites, which may lead to enhanced carrier scattering at grain boundaries. This causes a deterioration in the carrier mobility, even though the carrier concentration improves by two orders of magnitude due to doping. In addition, the Ag-doped SnO thin films show a p-type semiconductor behavior, with a direct optical gap and decreasing transmittance with increasing Ag dopant concentration.</P>
Finite element elastoplastic homogenization model of a corrugated-core sandwich structure
Viet D. Luong,Fazilay Abbès,Minh P. Hoang,Pham T.M. Duong,Boussad Abbès 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.3
This study aimed to develop an elastoplastic homogenization model to accurately predict the elastoplastic static behavior of a corrugated-core sandwich structure. A panel composed of two planar layers and one corrugated layer is modeled by a homogeneous orthotropic single-layer plate. A plane stress elastoplastic model is adopted to describe the behavior of each layer. Homogenization is achieved by local integration across the thickness of each layer. The proposed homogenization model is implemented in the ABAQUS finite element software using UGENS user subroutine. The results obtained by our model are compared to those obtained by full 3D simulations under different loading conditions. The comparisons show the efficiency and the accuracy of the proposed elastoplastic homogenization model.
Improving photocatalytic oxidation of semiconductor (TiO2, SnO2, ZnO)/CNTs for NOx removal
Hoang Phuong Nguyen,Thi Minh Cao,Tien-Thanh Nguyen,Viet Van Pham 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-
Traditional semiconductors, i.e., SnO2, ZnO, and TiO2 have a good photocatalytic activity but still manydisadvantages to applying in industry. In this study, these semiconductors are combined by commercialCNTs to form heterojunctions by a ball-milling route. The physical–chemical analyses include X-raydiffraction pattern (XRD), diffused reflectance spectra (UV–Vis DRS), Fourier transform infrared spectrum(FTIR), Mott-Schottky analysis, high-resolution transmission electron microscopy (HRTEM), and selectedarea electron diffraction (SAED) are run to characterize the as-prepared materials. The total photocatalyticNOx efficiency of SnO2/CNTs, ZnO/CNTs, and TiO2/CNTs composites generate green products, i.e.,NO3 – , HNO3, etc. with 10%, 10.1%, and 41.25% after 30 min under visible light illumination, respectively. We also found that ZnO/CNTs easily inactivated the photocatalytic ability and converted NO gas to a moretoxic product. Meanwhile, the highest selectivity of green products conversion belongs to SnO2/CNTsnanocomposite. Our findings will design and select an excellent photocatalytic oxidation system forNOx removal towards a flue gas treatment established.