Science & Technology Development Journal - Engineering and Technology http://stdjet.scienceandtechnology.com.vn/index.php/stdjet <p><span id="result_box" class="" lang="en"><span title="Tạp chí Phát triển Khoa học và Công nghệ (PTKH&amp;CN) của Đại học Quốc gia thành phố Hồ Chí Minh (ĐHQG-HCM) được thành lập từ năm 1997, ra số đầu tiên vào tháng 1 năm 1998. Từ năm 2006 Tạp chí đã"><strong>Science and Technology Development Journal</strong> (STDJ), Vietnam National University - Ho Chi Minh City (VNU-HCM) was established in 1997. And the first issue was published in January 1998 with </span><span title="đăng ký mã số chuẩn quốc tế ISSN 1859-0128.">ISSN 1859-0128. </span><span title="Từ đó cho đến nay, Tạp chí PTKH&amp;CN đã trở thành diễn đàn khoa học quan trọng nhất của đội ngũ cán bộ nghiên cứu, giảng viên, nghiên cứu sinh của ĐHQG-HCM và cũng là diễn đàn khoa học công nghệ đáng tin cậy của">Since then, STDJ has become the most important scientific forum of scientists from VNU-HCM as well as</span><span title="nhiều nhà nghiên cứu, giảng viên các trường đại học khác tại Việt Nam."> other universities. </span><span title="Tạp chí đã trải qua 20 năm phát triển và đã trở thành nhịp cầu giao lưu khoa học, cũng như làm phong phú tài liệu tham khảo cho đội ngũ giảng viên, nghiên cứu sinh, sinh viên ĐHQG-HCM nói riêng và các Trường đại">The magazine has undergone 20 years of development and has become a bridge for scientific exchanges, as well as enriching reference materials for the faculty, doctoral students, students of VNU-HCM in particular and other universities, institutes... </span></span></p> <p><span id="result_box" class="" lang="en"><span title="học phía Nam nói chung. "><br></span><span title="Tính đến hết năm 2016 Tạp chí đã xuất bản được 276 số với 2714 bài nghiên cứu của các nhà khoa học, cán bộ trong và ngoài ĐHQG-HCM trong 5 lĩnh vực nghiên cứu: Kỹ thuật và Công nghệ, Khoa học Tự nhiên,">By the end of 2016, the journal has published 276 issues with 2714 research articles in five areas of research: Engineering and Technology, Natural Sciences, </span><span title="Khoa học Xã hội và Nhân văn, Kinh tế luật và Khoa học Quản lý, Khoa học Trái đất và Môi trường tương ứng với 5 chuyên san chuyên ngành của Tạp chí.">Social Sciences and Humanities, Economics of Law and Management Sciences, Earth Sciences and Environment corresponding to 5 specialized journals of the Journal. </span></span></p> <p><span id="result_box" class="" lang="en"><span title="Tạp chí đã được phát hành tại các thư viện của các đơn vị thành viên của ĐHQG-HCM, các Sở Khoa học Công nghệ của các tỉnh thành trên cả nước và được Hội đồng học hàm Giáo sư Nhà nước đánh giá cao.">The magazine has been widely indexed in the various libraries at Vietnam. </span></span></p> Viet Nam National University Ho Chi Minh City en-US Science & Technology Development Journal - Engineering and Technology 2615-9872 <p>Copyright The Author(s) 2018. This article is published with open access by Vietnam National University, Ho Chi Minh city, Vietnam. This article is distributed under the terms of the&nbsp;<a href="https://creativecommons.org/licenses/by/4.0/" target="_blank" rel="noopener">Creative Commons Attribution License (CC-BY 4.0)</a> which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.&nbsp;</p> An implementation of lean manufacturing technology in enhancing efficiency in garment manufacturing industry with small and medium size http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/485 <p>Lean manufacturing technology has been applied in industry to eliminate wastes, enhance efficiency and increase competition ability. While some case studies were evaluated successfully, others faced with big challenges. Actually, lean was applied in different ways due to types and size of industry or organization. This paper would present an lean implementation process, in which lean tools are integrated in simultaneously. Requirements on system manufacturing capacity should be met, so necessary resources would be determined. Manufacturing layout and work flows would be created smoothly. The lean implementation process was applied in some case studies in garment industry with small and medium size, which show the efficiency and effectiveness of the lean technology in the practice systems. The research shows the good results on some performance key indexes such as productivity, ability to satisfy the orders and good working environment.</p> Hiền Ngọc Đỗ Quỳnh Lam Ngọc Lê ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-16 2021-04-16 4 2 771 781 10.32508/stdjet.v4i1.485 title description none g Study on a protection coordination approach for over-current relays in distribution generator-integrated distribution networks http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/764 <p>Presence of distributed generators (DGs) can impact on the operation reliability of over-current protection relays (OCPRs) which are installed to protect a distribution network (DN). Plug-and-play and peer-to-peer operating characteristics of DGs can make a significant change in fault current values, which could lead to protection mis-coordination or mal-function of adjacent OCPRs for a distribution network having DGs. Therefore, the OCPRs should be properly adjusted to get high sensitivity and selectivity when considering the DG's operating characteristics in the DN. In this paper, an Over-Current Protection Coordination Optimization (OCPCO) approach will be developed for a DG integrated distribution netwok. This developed OCPCO approach is based on fault analysis results combined with a selected meta-heuristic search algorithm, GSA (gravitational search algorithm), in order to determine coordination factors , , and corresponding to each OCPR and the configuration change of DG-based DN, specifically right after a FLISR (Fault Detection, Location, Isolation and Service Restoration) tool has proposed possible ISR (Isolation and Service Restoration) plans. An objective function of OCPCO approach is established by considering the total coordination time of consecutive OCPRs and will be then solved by the GSA method in order to find the best protection coordination solution with the effective coefficents , , and before updating them to the OCPRs by a communication system support. Simulation results of a real distribution network model with DG models from ETAP software are used for validating the proposed OCPCO approach in this research.</p> Phúc Duy Lê Hoan Thanh Nguyễn Phúc Công Huỳnh Dương Minh Bùi Minh Ngọc Đoàn Phương Thanh Nguyễn Khang Nguyên Trần ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-16 2021-04-16 4 2 782 805 10.32508/stdjet.v4i2.764 title description none g An improved fault analysis method based on bus-voltage thresholds determination for distribution networks with distributed generators http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/766 <p>Integration of distributed generators (DGs) into a distribution network (DN) can impact on the reliability operation and stability of protection systems. Depending on DG types, their installed locations, and operation states, fault current values in the distribution network can be significantly changed such that protective devices can inaccurately operate. Traditional fault analysis methods have not considered the presence of distributed generators and their operation characteristics, bidirectional power flows and change in bus-voltage values in the DN. Therefore, improvement of fault current calculation methods is necessary to fast, automatically and accurately determine fault current values in the DN with distributed generators. Hence, this paper develops an improved fault analysis method based on bus-voltage thresholds determination for distribution networks with DGs. The bus-voltage thresholds can be evaluated by determining load power confidence intervals (LPCI), and fault current thresholds will be then calculated in the DN with DGs. Based on a developed LPCI calculation tool and E-terra distribution software, achieved simulation results have validated the effectiveness of fault analysis method based on bus-voltage thresholds for distribution networks in case of considering types, locations and operation states of various distributed generators.</p> Phúc Duy Lê Dương Minh Bùi Minh Ngọc Đoàn Phương Thanh Nguyễn ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-16 2021-04-16 4 2 806 834 10.32508/stdjet.v4i2.766 title description none g Research and manufacture of external non-circular gear-pair with improved cycloid profile of the ellipse http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/773 <p>Non-circular gears (NCGs) are known as an alternative to conventional mechanical mechanisms in continuous speed converters. In which, the gear profile is the factor that directly affects the performance and quality meshing of the non-circular gear. However, the types of curves that are being used to generating profiles of the non-circular gears still exist limited in meeting the conditions of undercutting and uniformity of tooth sizes at different positions on the centrode. To optimize the profile of the non-circular gear, the paper presents a new profile in which the traditional involute profile of the non-circular gears is replaced by an improved cycloid curve of the ellipse. The mathematical model of new profile of non-circular gear is formed by eccentric circular shaper cutter with the improved cycloid of the ellipse in accordance with the theory of gearing in consideration of undercutting conditions. Based on the mathematical model established by this research, a program was written in Matlab. On that basis, a pair of non-circular gear was designed and fabricated experimentally on a wire breaker to verify the theory. The results show that with the new tooth profile design scheme, the shortcomings of uneven teeth on the non-circular gear of the traditional studies when using the involute profile of the circle have been overcome.</p> Thai Hong Nguyen Trung Thanh Nguyen Viet Hoang Nguyen ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-16 2021-04-16 4 2 835 845 10.32508/stdjet.v4i2.773 title description none g Space-vector modulation for three-phase indirect matrix converters to reduce common-mode voltage http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/797 <p>This paper presents a space vector modulation strategy for a three-phase indirect matrix converter to reduce the common-mode voltage and maintain the output performance. To reduce the peak value of the common-mode voltage to 57.7% of the input phase voltage, three active voltage vectors are used to generate the desired output voltage with arbitrary amplitude and frequency, instead of using both active and zero voltage vectors as in the traditional space vector modulation strategy. Although the common-mode voltage is reduced, the output waveform quality of the three-phase indirect matrix converter deteriorates due to the absence of the zero voltage vectors. To overcome this problem, the proposed space vector modulation strategy is redesigned to control the rectifier stage of the indirect matrix converter by utilizing three active current vectors instead of two as usual. Consequently, the constant average dc-link voltage is achieved, which can improve the output performance in terms of the output voltage and current harmonic distortion. The simulation is implemented by PSIM software and experimental results are provided to verify the effectiveness of the proposed space vector modulation strategy.</p> Hoan Quoc Tran Tien Manh Vu Tuyen Dinh Nguyen ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-18 2021-04-18 4 2 846 860 10.32508/stdjet.v4i2.797 title description none g A new design of the Lobe pump is based on the meshing principle of elliptical gear pairs http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/769 <p>The paper presents a new rotor design of an external coupling Lobe pump driven by pair of elliptical gears. The new rotor is a four-tooth elliptical gear with tooth profile is a improve cylocid curve. The improve cylocid curve is the locus of the fixed point on the generation circle, when the circle a pure rolling without slipping on the elliptical centrode of the rotor. The conditions of the rotor addendum and dedendum profiles are also considered. The limited supply angle addendum and dedendum rotor profiles are determined through an iterative algorithm when the generation circle makes a pure rolling without slipping on the ellipse base of the rotor. From there, we proceed to determine the pump design parameters according to the characteristic design parameters forming the rotor profile. The flow rate of the pump is determined by the area of the pockets on a cross-section perpendicular to the pump shaft. On that basis, a Matlab program is written from the mathematical model established by the paper to calculate the rotor design. In addition, the paper also investigates the effect of the coefficient l (semi-major axis divided semi-minor axis of the elliptical centrode ) on the average flow and axis distance. Survey results show that the design at l = 0.5 flow is 52.17% larger and the axis distance is reduced by 21.43% when compared to the traditional design at l = 1. This is the advantage of the new design proposed by this study.</p> Thai Hong Nguyen Nguyễn Duy Long ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-25 2021-04-25 4 2 861 871 10.32508/stdjet.v4i2.769 title description none g Decentralized control of level-shifted carrier-based pwm for modular multilevel interlinking converter in hybrid microgrid http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/787 <p>The interlinking converters is one of the important components in the hybrid mirogrid system, the study of structure and control method of the interlinking converters in hybrid mirogrid has been implemented and achieved positive results. This paper proposes an improved decentralized control of level-shifted carrier-based PWM for a modular multilevel interlinking converter (IC-MMC) in standalone hybrid microgrid (HMG-Hybrid Microgrid). Main research objectives is to study the capability of the decentralized control method proposed for the IC-MMC unit when performing the power exchange control task between the DC and AC bus in the HMG system, increased flexibility in controls. Furthermore, the proposed control method for IC-MMC for HMG is also verified in term of dynamically reconfiguration when changing the number of modules in the MMC when the improve of system reliability is needed. The feasibility of the carrier level shift control method for IC-MMC in HMG has been verified by simulation model on MATLAB/Simulink software to evaluate the ability to exchange power between the DC bus and the AC bus.</p> Quốc Dũng Phan Phu Cong NGUYEN Phuoc Hoa TRUONG Dinh Tuyen NGUYEN Duc Hung NGUYEN An Nhuan LE ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-25 2021-04-25 4 2 872 899 10.32508/stdjet.v4i2.787 title description none g Study on the content of some metals in soil by XRF method and evaluating their effect on the total phenolic and flavonoid content of methanol extracts from two medicinal plants in An Giang Province http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/798 <p>Several metals in soil affect the production of secondary metabolites in medicinal plants. In this study, we have determined concentrations of K, Mn, Fe, Zn, Cu in soils collected at Tinh Bien, Tri Ton, Thoai Son, and Cam Mountain areas in An Giang province by X-Ray Fluorescence Spectroscopy (XRF). We simultaneously evaluated the total phenolic and flavonoid content of methanol extracts from Solanum torvum (Sw.) leaves and Zingiber zerumbet (L.) rhizomes harvested in Tinh Bien and Cam Mountain. The results showed that the concentrations of metals reached the highest values at the soil particle size 0.25 mm among three sizes: 0.25 mm, 1 mm, and 2 mm. Whereas, the metal contents at two sampling depths 0-15 cm and 15-30 cm were similar. The concentrations of K and Cu in the soil in Tinh Bien are higher than Cam Mountain at 1.18 times and 1.70 times; however, the Fe, Zn, Mn content in Tinh Bien is lower at 2.16 times, 1.64 times, and 1.43 times. Thereby, it can be seen that the higher concentration of K and Cu may contribute to increasing the total phenolic content about 1.8 times with the Zingiber zerumbet (L.) rhizomes sample, and the flavonoid content by 2.5 times for the Solanum torvum (Sw.) leaves sample in Tinh Bien compared to Cam Mountain. Meanwhile, the concentrations of Fe, Zn, and Mn did not affect the flavonoid and phenolic content in these two plants</p> Hien Minh Nguyen Pham Tan Thi Nguyen Thi Dung Huynh Thi Kim Ngan Nguyen Thi Yen Nhi Le Minh Tri ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-25 2021-04-25 4 2 900 909 10.32508/stdjet.v4i2.798 title description none g Application of artificial neural network in neutron/gamma pulse shape discrimination for EJ301 scintillation detector http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/803 <p>The scintilator detectors are sensitive to both neutron and gamma radiation. Therefore, right identification of the pulses which generated by neutrons or gamma ray from these detectors plays an important role in neutron measurement by using scintilator detector. In order to improve the ability to pulse shape discrimination (PSD), many PSD techniques have been studied, developed and applied. In this work, we use a basic configuration of a Fully connected Neural network (Fc- Net) where the number of elements of the network is minimum, and each element corresponds to identified specification of neutron or gamma pulses measured by using EJ-301 scintilator detector. The minimum of error principle has been applied for neuron network design; therefore, the accuracy of recognitions did not affect by this reduced network. The obtained results show that the identify accuracy of FcNet is higher than those of digital charge integration (DCI) method. Being tested using 60Co radioactive source, it is shown that, with the application of the FcNet, the accuracy of the gamma pulses discrimination acquires 98.60% in the energy region from 50 to 2000 keV electron equivalent energy (keVee), and 95.59% in the energy region from 50 to 150 keVee. In general, the obtained results indicate that the artificial neural network method can be applied to build neutron/gamma spectrometers with limited hardware.</p> Chuân Văn Phan Hải Xuân Nguyễn Anh Ngọc Nguyễn Hải Xuân Phạm Phong Xuân Mai Khang Đình Phạm Minh Văn Trương Tài Thanh Dương Duyên Thị Hoàng Lưu ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-04-30 2021-04-30 4 2 910 919 10.32508/stdjet.v4i2.803 title description none g Hydrodynamic studies on liquid-liquid two phase flow separation in microchannel by computational fluid dynamic modelling http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/810 <p>Microfluidic systems undergo rapid expansion of its application in different industries over the few decades as its surface tension-dominated property provides better mixing and improves mass transfer between two immiscible liquids. Synthesis of biodiesel via transesterification of vegetable oil and methanol in microfluidic systems by droplet flow requires separation of the products after the reaction occurred. The separation technique for multiphase fluid flow in the microfluidic system is different from the macro-system, as the gravitational force is overtaken by surface force. To understand these phenomena completely, a study on the hydrodynamic characteristics of two-phase oil-methanol system in microchannel was carried out. A multiphase Volume of Fluid model was developed to predict the fluid flow in the microchannel. An inline separator design was proposed along with its variable to obtain effective separation for the oil-methanol system. The separation performance was evaluated based on the amount of oil recovered and its purity. The capability of the developed model has been validated through a comparison of simulation results with published experiment. It was predicted that the purity of recovered oil was increased by more than 46% when the design with side openings arranged at both sides of the microchannel. The highest percentage recovery of oil from the mixture was simulated at 91.3% by adding the number of side openings to ensure the maximum recovery. The oil that was separated by the inline separator was predicted to be at 100% purity, which indicates that no methanol contamination throughout the separation process. The purity of the separated product can be increased by manipulating the pressure drop across the side openings. Hence, it can be concluded that the separation in a large diameter microchannel system is possible and methodology can be tuned to achieve the separation goal. Finally, the simulation results showed that the present volume of fluid model had a good agreement with the published experiment.</p> Chue Cui Ting Afiq Mohd Laziz Khoa Dang Dang Bui Ngoc Thi Nhu Nguyen Pha Ngoc Bui Khoa Ta Dang An Si Xuan Nguyen Ngon Trung Hoang Ku Zilati Ku Shaari Hoàng Huy Phước Lợi Phạm ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-05-09 2021-05-09 4 2 920 931 10.32508/stdjet.v4i2.810 title description none g Identifying the drivers of liking for texture attributes of Vietnamese sausage http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/819 <p>Vietnamese sausage (cha lua), a pork processing food with a characteristic chewy and crunchy texture, are widely consumed in Vietnam. However, there are not many established researchs on hedonic and sensory attributes for this product, especially about the texture attributes. The goal of this study was to investigate consumer's preference as well as identify the drivers of liking for texture of Vietnamese sausage. Eight samples were prepared with various ratio of lean meat, lard and starch to cover a wide range of different texture of Vietnamese sausage. Sixty eight consumers then evaluated these eight samples, rating texture liking on nine-point scale and answering a checkall- that-apply (CATA) question, which consisted of 16 different texture attributes of Vietnamese sausage. The consumers were also asked to check all the approriate attributes to describe their ideal products. The ANOVA and post –hoc test showed samples which had recipes with high lard ratio (20-25%) and low meat ratio (70%) had a significant higher liking scores, while the samples which had recipe with high meat ratio (90%) had the lowest liking scores. The Cochran's Q test showed that 12 attributes had different choice frequency between samples, suggesting the texture of Vietnamese sausage is complex and diverse. The CA results showed all the samples without stach were associated with large air holes, while samples which high meat ratio (80%) were associated with hardness. The ideal Vietnamese sausage product was associated with fattiness, juiciness, springiness and brittleness. Finally, the results of penalty analysis showed that chewy, firm, and elastic attributes had positive impacts on the liking score for Vietnamese sausage products, while attributes that exhibit heterogeneity, such as large air hole and grainy, significantly reduced the liking score of the product. This suggested the importance of mechanical texture attributes and homogenity on the consumer's preference of the Vietnamese sausage.</p> Thịnh Hữu Phạm Nguyễn Vũ Vân Thủy Nguyễn Hoàng Dũng Nguyễn Thị Hiền ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-05-10 2021-05-10 4 2 first first 10.32508/stdjet.v4i2.819 title description none g Research of decentralized loop automation simulation in distribution network using MALAB/SIMULINK http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/818 <p>Nowadays, technologies are rapidly developing, automation is omnipresent in our life. In the power system, automation technology solutions have been applied gradually and widely to meet the requirements of reliability. Before, when a fault occurs on the distribution network, the fault locating, isolating and grid restoring are still being done manually, so a large number of customers that are not in the fault zone still suffer outage for a long time. Distribution Automation System was developed to solve this problem. Currently, with the development of information technology, the Decentralized Loop Automation (DLA) in the distribution network is carried out by communication between the protective devices in the grid. Communication between devices can be done using time-control rules, using GOOSE messages, wifi or according to protocol IEC 61850. In addition, the protective devices can be connected to the control center to create a Centralized Loop Automation (CLA) in the distribution network. The paper considers the DLA solution with the time-control rules for a simple grid. Time-control rules models and simulation results were performed on MATLAB/ SIMULINK software. The paper proposed a user interface for DLA solution with many different failure cases, especially considering the protection coordination in case of doubles failure. The results of the paper show that DLA can isolate faults automatically and restore the grid in a short time, and these results can be developed as an experimental simulation in the future.</p> Tuyen Thi Bich Nguyen Minh Thi Tinh Le Dat Tien Huynh ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-05-12 2021-05-12 4 2 first first 10.32508/stdjet.v4i2.818 title description none g Turning dynamics analysis of a heavy articulated vehicle by the vehicle planar dynamic model with two steering input signals http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/767 <p>The vehicle planar single track dynamic model with two input steering angle parameters is derived by using Lagrange's method with the basis of equations for calculating the tire's force components. Dynamic analysis of a heavy articulated vehicle in case of turing is carried out by the vehicle planar dynamic model, in which two input steering angles are taken into account. Simulation with the selected velocity value to make sure that the stability according to the friction conditions at all axles of the vehicle is satisfied. Turning spacing, lateral forces at each axle of the vehicle are determined and analyzed for all three different cases of steering angles, respectively with steering angle of the semi-trailer is in the same direction, in the opposite direction and is locked or not steered in comparision with the steering angle of the tractor. The obtained results show that the derived model could employ to determine the planar kinematic and dynamic parameters, and analyze the dynamic safety features of an articulated vehicle, too. In addition, the derived mathematical model could also employ to develop a computational model that controls the planar articulated vehicle dynamics.</p> TRAN Huu Nhan Nguyễn Văn Hoàng ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2021-05-09 2021-05-09 4 2 932 939 10.32508/stdjet.v4i2.767 title description none g