High-Efficient Energy Harvester With Flexible Solar Panel for a Wearable Sensor Device

Tran, Thang Viet,Chung, Wan-Young IEEE 2016 IEEE SENSORS JOURNAL Vol.16 No.24

<P>This paper proposes an optimal energy harvester (OEH) that uses a flexible photovoltaic (FPV) module to prolong battery life for a wearable body sensor node under indoor and outdoor conditions. The proposed sensor node uses a Bluetooth low- energy module, which consumes low power to wirelessly communicate with mobile devices for monitoring vital signals. A 19 cm x 4 cm FPV module that can easily conform to human body contours is used for generating a peak- power of up to 500 mW to charge the battery in outdoor environments. To optimize the power collected under various irradiances, the OEH is designed with a boost circuit for harvesting the low energy available indoors and a maximum power point tracker for collecting the high energy that is available outdoors. The booster can operate within a wide input voltage range of 0.65- 3 V to generate a stable output voltage of 3.3 V, and it has a high conversion efficiency of similar to 95%. The MPPT uses fuzzy inference engine to find the MPP of the FPV that is required to power the system. The results of our experiment show that the proposed device can prolong the lifetime by up to 950% under an irradiance of only 2.9 mW/cm(2), and the proposed node becomes an autonomous node under partial shading and sunlight conditions. Therefore, this paper can provide a useful solution for extending the lifetime of wearable sensor devices.</P>

Battery-free smart-sensor system for real-time indoor air quality monitoring

Tran, Thang Viet,Dang, Nam Trung,Chung, Wan-Young Elsevier 2017 Sensors and actuators. B Chemical Vol.248 No.-

<P><B>Abstract</B></P> <P>Indoor air pollution is one of the serious issues that affect public health nowadays. Therefore, indoor air quality needs to be monitored by a real-time system for early air pollution warning. Until now, most wireless sensors used for air quality monitoring have required power supply from a battery for sensor operation and wireless data communication. This battery, which is attached to a sensing module, makes the wireless sensing module larger and requires regular replacement efforts and high costs. The present study proposes a novel battery-free sensor module to measure the concentration of volatile organic compounds, ambient temperature, relative humidity, and atmospheric pressure for monitoring air quality in indoor environment. The proposed system comprises a smart-sensor tag, and a radio frequency (RF) energy harvester. The sensing circuit, designed using ultra-low power sensors and a microcontroller unit (MCU), consumes low average power of only 0.5mW. The MCU collects data from the sensors and writes the sensing data to the memory in the form of an Electronic Product Code (EPC) Class 1 Generation 1 compliant identification (ID) of the tag. The RF energy harvester with a highly efficient buck–boost converter and a 50-mF supercapacitor for real-time saving of the collected power can sufficiently collect the available RF energy from the reader within a maximum distance of ∼250cm from the reader to supply power for sensing and wireless communication operation of the smart-sensor tag. Therefore, the proposed smart-sensor module can be a battery-free sensor device for monitoring environment parameters in indoor condition. Experiments are conducted to validate and support the developed system for real-time air quality monitoring and warning.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper proposes a novel battery-free sensor module to monitor indoor air quality. </LI> <LI> The proposed smart-sensor module using ultra-low power sensors, a highly efficient radio frequency harvester, and a sequential sensing method does not require any extra battery for operation. </LI> <LI> The proposed study can be a promising solution for real-time air quality monitoring and warning. </LI> </UL> </P>

A Robust Peak Detection Algorithm for Photoplethysmographic Waveforms in Mobile Devices

Tran, Thang Viet,Chung, Wan-Young American Scientific Publishers 2017 Journal of medical imaging and health informatics Vol.7 No.7

A Robust Algorithm for Real-Time Peak Detection of Photoplethysmograms Using a Personal Computer Mouse

Thang Viet Tran,Wan-Young Chung IEEE 2015 IEEE Sensors Journal Vol. No.

<P>Monitoring the photoplethysmogram (PPG) signal is essential for cardiovascular patients in the hospital or at home, as well as for those working in front of a personal computer (PC) at the office every day. Therefore, we developed a wireless PPG mouse that consists of a PC mouse, PPG sensor, and Bluetooth mote. The sensor is located within the PC mouse, therefore, the structure of the ordinary mouse is not changed. A user's thumb can easily touch the surface of a sensor for PPG signal monitoring. However, it is challenging to process the signals collected from the PPG mouse, especially in the cases where the mouse moves quickly or the user performs multiple actions on the mouse buttons. In this paper, we propose a robust algorithm to detect the PPG peak under big motion artifact conditions. In the proposed algorithm, an adaptive method enables simultaneous detection of true peaks and eliminates fake peaks from the acquired PPG signal. Next, these detected error peaks can be corrected by a random error estimator. The combination of two sequential methods enhances the robustness of the algorithm for distinguishing irregular PPG patterns. The proposed algorithm presents an advantage for real-time applications and continuous heart rate monitoring systems using a wireless PPG sensor implemented in a PC mouse.</P>

휘도 성분의 공간적 상관도 및 적응적 임계치를 이용한 컷 검출

트란비엣탕(Tran Viet Thang),구동수(Dong Soo Koo),홍충선(Choong Seon Hong),이대영(Dae Yooung Lee) 한국통신학회 1999 한국통신학회 학술대회논문집 Vol.1999 No.11

Enhancing Salp Swarm Optimization with Orthogonal Diagonalization Transformation for Damage Detection in Truss Bridge

Hung Tran Viet,Thanh Nguyen Chi,Thang Le Xuan,Nhung Nguyen Cam,Thuc Ngo Van,Hoa Tran 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.6

This paper proposes a novel approach for structural damage identification using the Salp Swarm Algorithm (SSA) combined with Orthogonal Diagonalization (OD). SSA is an optimization algorithm developed in recent years and has been considered for addressing complex and computationally expensive engineering problems. However, due to the utilization of only the leader salp to search for optimal solutions, there is an imbalance between the exploitation and exploration capabilities of the salp swarm. To address this issue, we suggest the use of OD to enhance the search capability of the leader salp. OD plays a crucial role in reducing the search space and selecting high-quality salp elements in subsequent iterations. From that idea, the algorithm is tested with 12 benchmark functions, and the results demonstrate superior convergence for all of these compared to the algorithm without OD. A comprehensive study with various damage scenarios is also conducted with the Cua Rao bridge. The outcomes indicate that the accuracy, with a deviation rate when using OD, is only 1.412%, whereas it is 2.224% for the SSA in the case of a single damage scenario. As the number of damaged elements increases, the error of SSA rises to 99.667% when identifying damaged elements, while errors using OD remain below 10%. Additionally, the computational speed is significantly enhanced by approximately 40% in both scenarios.

The Relationship between Corporate Social Responsibility and Customer Purchase Intention: Empirical Evidence from Vietnam

Thang Quang TRAN,Ninh Truong Thi THUY,Dung Viet PHAM 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.5

Corporate social responsibility is becoming increasingly important to organizations, and it has received a lot of attention from the general public and marketing academics. This study aimed to look at the many aspects of corporate social responsibility and see how brand reputation and brand love play a role in the relationship between corporate social responsibility and customer purchase intent. To reach the end, this research applied the theory of social exchange and corporate social responsibility to explain the relationship between the variables. The Partial Least Squares was applied to analyze data collected from survey questionnaires in the Hanoi market (Vietnam) to test the proposed hypothesis. The study resulted in 239 valid survey questionnaires which can be used to test hypotheses by applying SmarPLS software. The results indicated that there are three key elements of corporate social responsibility from customers’ perspectives: responsibility to customers, responsibility to the environment, and responsibility to the community. Interestingly, brand reputation and brand love contribute as mediating roles in the correlation between corporate social responsibility and customer purchase intention. Finally, the authors discussed the findings and the implications of this research in both theoretical and practical aspects, as well as the limitations that future research can focus on.

Predictive value of the negative inspiratory force index as a predictor of weaning success: a crosssectional study

Vu Phuong Hoang,Tran Viet Duc,Duong Minh Cuong,Cong Quyet Thang,Nguyen Thu 대한중환자의학회 2020 Acute and Critical Care Vol.35 No.4

Background: Identifying when intubated patients are ready to be extubated remains challenging. The negative inspiratory force (NIF) is a recommended predictor of weaning success. However, little is known about the role of NIF in the weaning process for the Asian surgical intensive population, especially for the Vietnamese population. Here, we aimed to investigate the cutoff threshold and predictive value of the NIF index for predicting the success of ventilator weaning in Vietnamese surgical intensive care patients. Methods: A cross-sectional study was conducted at the Surgical Intensive Care Unit of Viet Duc Hospital from October 2016 to August 2017. A total of 64 patients aged 16–70 years undergoing ventilatory support through an orotracheal tube satisfied the criteria for readiness to begin weaning. The correlation between the NIF index with outcomes of the weaning process was analyzed. Specificity (Sp), sensitivity (Se), positive predictive value (PPV), negative predictive value (NPV), receiver operating characteristic (ROC) curve, and area under the curve (AUC) were calculated. Results: The success rate of the entire weaning process was 67.2% (43/64). The median NIF values were –26.0 cm H2O (interquartile range [IQR], –28.0 to –25.0) in the successful weaning group and –24.0 cm H2O (IQR, –25.0 to –23.0) in the weaning failure group (P<0.001). According to ROC analysis, an NIF value ≤–25 cm H2O predicted weaning success (AUC, 0.836) with 91% Se, 62% Sp, 83% PPV, and 77% NPV. Conclusions: An NIF cutoff threshold ≤–25 cm H2O can be used as predictor of weaning success in Vietnamese surgical intensive care patients.

A Novel Heuristic Algorithm for Online 3D Bin Packing

Thanh-Hung Nguyen,Viet-Thang Tran,Phan-Quan Doan,Thi-Thoa Mac 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

The paper presents a novel heuristic algorithm to solve the problem of automatically packing 3-dimensional boxes into containers. In this application, the collection of boxes is unknown, and a box must be packed immediately before the next box appears. The algorithm is developed based on the main and secondary data systems. The main data system describes the spaces that are large enough to fit a box. The secondary data system describes the small spaces that cannot accommodate boxes. The search algorithm based on these two data systems allows to reduce the workload of searching and is convenient in organizing and editing data systems. Experimental results show that this method is superior in terms of processing speed and packed volume ratio.

The Hedonic Method in Evaluating Apartment Price: A Case of Ho Chi Minh City, Vietnam

NGUYEN, Ha Minh,PHAN, Hung Quoc,TRAN, Tri Van,TRAN, Thang Kiem Viet Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6

The study examines factors affecting apartment prices in the real estate market of Ho Chi Minh City, Vietnam. The study uses primary data based on surveys of customers who have traded successfully, and collects transaction data from real estate trading companies that are the top investors in Ho Chi Minh City real estate market. The collected data include 384 observations in a total of 24 districts, detailing that each district surveyed on a minimum of four projects, each project carried out a survey on a minimum of four apartments. The survey collected 339 valid questionnaires for analysis and model testing. This study employs multivariate regression with the data of 339 observations. The research results reveal that five significant factors affect positively the price of apartments in Ho Chi Minh City - apartment area, toilet and bedroom, apartment floor, reference price, and apartment interior. Besides, there are three significant factors affecting negatively the price of apartments - next price trend, distance to city center, and potential building. From the results, the research proposes solutions in the pricing of apartments in the real estate market in Ho Chi Minh City - better information system, a real estate transaction index, and stricter management of small brokerage activities.