The research aimed to increase certain HbA1c concentrations at medical decision levels for extern... more The research aimed to increase certain HbA1c concentrations at medical decision levels for external quality control samples from healthy donor blood. The in vitro study was performed from October 2019 to January 2021 at Quality Control Center for Medical Laboratory at University of Medicine and Pharmacy at Ho Chi Minh City. The study observed on the conditions including the optimal buffer solutions (BAGPM, BPS, Ringer, Saline), temperature (2°C - 8°C, 22°C - 24°C, 37°C), and glucose concentration (100 mM, 305 mM, 500 mM) affecting the HbA1c concentration in vitro to make the external quality control samples fell in normal, prediabetes, and diabetes range. At every condition, the HbA1c concentration was measured by Tina Quant method to look for the optimal procedure to increase HbA1c concentration required of the external quality control protocol. The highest HbA1c concentration (11.57±0.2%) was found in BAGPM solution with 100 mM glucose after 15 days with the baseline HbA1c 5.43±0....
2021 IEEE International Electric Machines & Drives Conference (IEMDC)
Many modern direct-drive wind generators at high power levels adopt permanent magnet synchronous ... more Many modern direct-drive wind generators at high power levels adopt permanent magnet synchronous generators (PMSGs). Typically, these PMSGs are coupled with fully rated active rectifiers to process and deliver power to the main grid. However, the limited-speed nature of a wind turbine creates an opportunity to reduce the amount of active rectification required, which in turn would reduce the cost of the drive and improve system reliability. This paper presents a design and optimization process of a direct-drive PMSG coupled to an integrated generator-rectifier system. In order to make the hybrid architecture possible, a multi-port generator is designed with multiple diode rectifiers and a single active rectifier. This paper describes a process for a 10 MW generator-drive optimization under the proposed architecture with two different implementation methods. These implementations are compared using optimal Pareto front from a system-level efficiency-weight perspective.
International Journal of Emerging Technologies in Learning (iJET), 2022
Machine learning has globally become a trend in most educational settings. This study aims to exp... more Machine learning has globally become a trend in most educational settings. This study aims to explore students’ perceptions when using Google Translate (GT) to support their learning as well as their problems and solutions from GT. With the participation of 250 university students at a private educational institution, a 5-point Likert-scale questionnaire and a semi-structured interview were employed to examine how students perceived the use of GT in their learning process. The findings revealed that practically students had positive perceptions on GT’s use in learning. Several major problems were recorded when they used GT, and some recommended solutions were also considered for improvement. Specifically, students utilized GT as a learning tool, particularly for language study, because of its useful features such as multi-language translation, time saving, ease of use, and improving pronunciation. Although Google Translate has a number of advantages for students, several problems su...
2017 IEEE International Conference on Big Data (Big Data), 2017
Customer retention is regarded as one of the most concerns in any company, since they provide the... more Customer retention is regarded as one of the most concerns in any company, since they provide the fundamental source of revenue for business. Losing customers not only loses the profit, but also may put a whole business in danger. In order to increase customer base, businesses need to improve both acquisition and retention of its customers. Therefore, customer churn prediction is becoming the top concerns that many companies devoted their time and resources to address it. This paper presents the customer churn prediction on an extremely imbalanced data in an Internet Service Provider company to identify the users at the risk of leaving the services. It consists of feature engineering and predictive modeling. In the feature engineering, the most essential features are selected from a large number of created candidates. In the predictive modeling, the imbalance between the number of churners and non-churners was reduced using SMOTE oversampling technique before implementing several models such as AdaBoost, Extra Trees, KNN, Neural Network and XGBoost. Comparing between these models in term of precision and recall, the XGBoost model gives the highest performance. Using the dataset with 98% non-churners and 2% churners, precision and recall of the model are 45.71% and 42.06%, respectively.
Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc du... more Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc duy trì độ tin cậy của những OCPR quá dòng OCPR (Over-current Protection Relay) khi hoạt động để bảo vệ lưới điện phân phối (LĐPP). Trong quá trình vận hành để đảm bảo cung cấp điện cho LĐPP, những đặc tính vận hành của nguồn DG đã làm thay đổi đáng kể giá trị dòng điện sự cố và đây là nguyên nhân chính dẫn đến những hiện tượng OCPR hoạt động không tin cậy, chẳng hạn như mất tính chọn lọc, giảm độ nhạy, hoạt động vượt cấp hoặc hoạt động đồng thời. Do đó, việc điều phối những OCPR thuộc hệ thống bảo vệ trên LĐPP có xem xét đến những đặc tính vận hành của nguồn DG nhằm đảm bảo tính phối hợp khi hoạt động là cần thiết. Trong nghiên cứu này, nhóm tác giả sẽ giới thiệu về một phương pháp điều phối bảo vệ OCPCO (Over-current Protection Coordination Optimization) dành cho hệ thống bảo vệ của LĐPP có tích hợp nguồn DG. Cụ thể, phương pháp OCPCO này được phát triển dựa vào việc sử dụng kết quả phân...
2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019
An integrated generator-rectifier system has been shown to be beneficial in reducing ac-to-dc con... more An integrated generator-rectifier system has been shown to be beneficial in reducing ac-to-dc conversion loss at megawatt power level. The architecture incorporates passive and active rectifiers into a multi-port permanent magnet synchronous generator. With a conventional sinusoidal back emf, filter capacitors are required on passive rectifiers to create a low-ripple-voltage dc bus. These capacitors are bulky, unreliable, and reduce the power factor on the ac ports. Consequently, the generator must be over designed to accommodate high peak ac current. This paper proposes an alternative back emf shape, relying on the trapezoidal waveform. The proposed back emf accomplishes debus ripple voltage of less than 5% at a high power factor using a capacitor-less passive rectifier. In addition, the generator torque ripple is reduced compared to a sinusoidal-back-emf machine. This opens an opportunity for compact generator design while further reducing the power electronics size, weight, and cost. The relationship between the dc-bus ripple voltage and the trapezoidal back emf is developed analytically. The findings are used to shape the generator back emf and select the range of the synchronous inductance. Simulation and experimental results corroborate the proposed approach.
2019 IEEE Electric Ship Technologies Symposium (ESTS), 2019
Future ships are envisioned to be electric with a medium-voltage dc grid feeding all the subsyste... more Future ships are envisioned to be electric with a medium-voltage dc grid feeding all the subsystems, including propulsion, weapons, and auxiliary loads. Gas-turbine driven ac generators are prominent candidates for shipboard electricity generation due to a high energy density. Consequently, megawatt-class ac-to-dc conversion systems are essential to make electric ships feasible. At medium-voltage and megawatt power, conventional ac-to-dc conversion systems are challenged by limited power electronics switch-voltage ratings, high conversion loss, convoluted circuitry, and complex control schemes. An integrated generator-rectifier system has been proposed as an alternative that employs low-voltage switches to form a medium-voltage dc bus. Low conversion losses and high system reliability are achieved by shifting power to the efficient passive rectifiers. This paper presents an integrated design in context of shipboard power system. Theoretical analyses show the size of the active rectifier is reduced by 37% and the total conversion loss is cut by 50A laboratory setup is established to corroborate the proposed system.
E–payment is one of the major constituents of e–commerce, which assists to enhance user efficienc... more E–payment is one of the major constituents of e–commerce, which assists to enhance user efficiency and smarten intention to use of e–commerce in the digital era. This study investigates the roles of perceived risk and trust on e–payment adoption. Data is collected from respondents who have used or intend to use e–payments for e–commerce in Ho Chi Minh City. The structural equation modelling (SEM) is analyzed on a total convenient sampling of 200 respondents. Interestingly, research results externalize that perceived risk and trust have the principal roles of the structural model of e–payment adoption. The research model accounts for 38% of e–payment adoption.
The research aimed to increase certain HbA1c concentrations at medical decision levels for extern... more The research aimed to increase certain HbA1c concentrations at medical decision levels for external quality control samples from healthy donor blood. The in vitro study was performed from October 2019 to January 2021 at Quality Control Center for Medical Laboratory at University of Medicine and Pharmacy at Ho Chi Minh City. The study observed on the conditions including the optimal buffer solutions (BAGPM, BPS, Ringer, Saline), temperature (2°C - 8°C, 22°C - 24°C, 37°C), and glucose concentration (100 mM, 305 mM, 500 mM) affecting the HbA1c concentration in vitro to make the external quality control samples fell in normal, prediabetes, and diabetes range. At every condition, the HbA1c concentration was measured by Tina Quant method to look for the optimal procedure to increase HbA1c concentration required of the external quality control protocol. The highest HbA1c concentration (11.57±0.2%) was found in BAGPM solution with 100 mM glucose after 15 days with the baseline HbA1c 5.43±0....
2021 IEEE International Electric Machines & Drives Conference (IEMDC)
Many modern direct-drive wind generators at high power levels adopt permanent magnet synchronous ... more Many modern direct-drive wind generators at high power levels adopt permanent magnet synchronous generators (PMSGs). Typically, these PMSGs are coupled with fully rated active rectifiers to process and deliver power to the main grid. However, the limited-speed nature of a wind turbine creates an opportunity to reduce the amount of active rectification required, which in turn would reduce the cost of the drive and improve system reliability. This paper presents a design and optimization process of a direct-drive PMSG coupled to an integrated generator-rectifier system. In order to make the hybrid architecture possible, a multi-port generator is designed with multiple diode rectifiers and a single active rectifier. This paper describes a process for a 10 MW generator-drive optimization under the proposed architecture with two different implementation methods. These implementations are compared using optimal Pareto front from a system-level efficiency-weight perspective.
International Journal of Emerging Technologies in Learning (iJET), 2022
Machine learning has globally become a trend in most educational settings. This study aims to exp... more Machine learning has globally become a trend in most educational settings. This study aims to explore students’ perceptions when using Google Translate (GT) to support their learning as well as their problems and solutions from GT. With the participation of 250 university students at a private educational institution, a 5-point Likert-scale questionnaire and a semi-structured interview were employed to examine how students perceived the use of GT in their learning process. The findings revealed that practically students had positive perceptions on GT’s use in learning. Several major problems were recorded when they used GT, and some recommended solutions were also considered for improvement. Specifically, students utilized GT as a learning tool, particularly for language study, because of its useful features such as multi-language translation, time saving, ease of use, and improving pronunciation. Although Google Translate has a number of advantages for students, several problems su...
2017 IEEE International Conference on Big Data (Big Data), 2017
Customer retention is regarded as one of the most concerns in any company, since they provide the... more Customer retention is regarded as one of the most concerns in any company, since they provide the fundamental source of revenue for business. Losing customers not only loses the profit, but also may put a whole business in danger. In order to increase customer base, businesses need to improve both acquisition and retention of its customers. Therefore, customer churn prediction is becoming the top concerns that many companies devoted their time and resources to address it. This paper presents the customer churn prediction on an extremely imbalanced data in an Internet Service Provider company to identify the users at the risk of leaving the services. It consists of feature engineering and predictive modeling. In the feature engineering, the most essential features are selected from a large number of created candidates. In the predictive modeling, the imbalance between the number of churners and non-churners was reduced using SMOTE oversampling technique before implementing several models such as AdaBoost, Extra Trees, KNN, Neural Network and XGBoost. Comparing between these models in term of precision and recall, the XGBoost model gives the highest performance. Using the dataset with 98% non-churners and 2% churners, precision and recall of the model are 45.71% and 42.06%, respectively.
Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc du... more Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc duy trì độ tin cậy của những OCPR quá dòng OCPR (Over-current Protection Relay) khi hoạt động để bảo vệ lưới điện phân phối (LĐPP). Trong quá trình vận hành để đảm bảo cung cấp điện cho LĐPP, những đặc tính vận hành của nguồn DG đã làm thay đổi đáng kể giá trị dòng điện sự cố và đây là nguyên nhân chính dẫn đến những hiện tượng OCPR hoạt động không tin cậy, chẳng hạn như mất tính chọn lọc, giảm độ nhạy, hoạt động vượt cấp hoặc hoạt động đồng thời. Do đó, việc điều phối những OCPR thuộc hệ thống bảo vệ trên LĐPP có xem xét đến những đặc tính vận hành của nguồn DG nhằm đảm bảo tính phối hợp khi hoạt động là cần thiết. Trong nghiên cứu này, nhóm tác giả sẽ giới thiệu về một phương pháp điều phối bảo vệ OCPCO (Over-current Protection Coordination Optimization) dành cho hệ thống bảo vệ của LĐPP có tích hợp nguồn DG. Cụ thể, phương pháp OCPCO này được phát triển dựa vào việc sử dụng kết quả phân...
2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019
An integrated generator-rectifier system has been shown to be beneficial in reducing ac-to-dc con... more An integrated generator-rectifier system has been shown to be beneficial in reducing ac-to-dc conversion loss at megawatt power level. The architecture incorporates passive and active rectifiers into a multi-port permanent magnet synchronous generator. With a conventional sinusoidal back emf, filter capacitors are required on passive rectifiers to create a low-ripple-voltage dc bus. These capacitors are bulky, unreliable, and reduce the power factor on the ac ports. Consequently, the generator must be over designed to accommodate high peak ac current. This paper proposes an alternative back emf shape, relying on the trapezoidal waveform. The proposed back emf accomplishes debus ripple voltage of less than 5% at a high power factor using a capacitor-less passive rectifier. In addition, the generator torque ripple is reduced compared to a sinusoidal-back-emf machine. This opens an opportunity for compact generator design while further reducing the power electronics size, weight, and cost. The relationship between the dc-bus ripple voltage and the trapezoidal back emf is developed analytically. The findings are used to shape the generator back emf and select the range of the synchronous inductance. Simulation and experimental results corroborate the proposed approach.
2019 IEEE Electric Ship Technologies Symposium (ESTS), 2019
Future ships are envisioned to be electric with a medium-voltage dc grid feeding all the subsyste... more Future ships are envisioned to be electric with a medium-voltage dc grid feeding all the subsystems, including propulsion, weapons, and auxiliary loads. Gas-turbine driven ac generators are prominent candidates for shipboard electricity generation due to a high energy density. Consequently, megawatt-class ac-to-dc conversion systems are essential to make electric ships feasible. At medium-voltage and megawatt power, conventional ac-to-dc conversion systems are challenged by limited power electronics switch-voltage ratings, high conversion loss, convoluted circuitry, and complex control schemes. An integrated generator-rectifier system has been proposed as an alternative that employs low-voltage switches to form a medium-voltage dc bus. Low conversion losses and high system reliability are achieved by shifting power to the efficient passive rectifiers. This paper presents an integrated design in context of shipboard power system. Theoretical analyses show the size of the active rectifier is reduced by 37% and the total conversion loss is cut by 50A laboratory setup is established to corroborate the proposed system.
E–payment is one of the major constituents of e–commerce, which assists to enhance user efficienc... more E–payment is one of the major constituents of e–commerce, which assists to enhance user efficiency and smarten intention to use of e–commerce in the digital era. This study investigates the roles of perceived risk and trust on e–payment adoption. Data is collected from respondents who have used or intend to use e–payments for e–commerce in Ho Chi Minh City. The structural equation modelling (SEM) is analyzed on a total convenient sampling of 200 respondents. Interestingly, research results externalize that perceived risk and trust have the principal roles of the structural model of e–payment adoption. The research model accounts for 38% of e–payment adoption.
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