Journal of Science and Technology - IUH

PHYSICAL CHARACTERISTICS OF DREDGING SOIL REINFORCED WITH FLY ASH

Huỳnh Xuân Thế — 2024-10-31

Vietnam is a developing country, so the demand for construction and industrial development is increasing. The current problems are as follows: (1) The source of alluvial soil materials, such as sand and good soil, is running out, limiting the exploitation of this resource due to its negative environmental impact; (2) Waste from thermal power plants, such as fly ash, has a detrimental effect on the living environment of humans; (3) There is still no established reuse plan to minimize construction costs and mitigate the negative environmental impact of dredged soil from construction. Research on the reuse of dredged soil is a topic of interest to both domestic and foreign researchers. The purpose of this article is to investigate the physical properties of a mixture of dredged soil and fly ash. The research results aim to examine how the properties of the mixed materials change with varying fly ash contents compared to pure dredged soil. This evaluation will help determine the applicability of using mixed materials to fill dredged soil in construction projects.

INVESTIGATING THE ELECTROCHEMICAL BEHAVIOR OF REINFORCING STEEL IN PATCHING-REPAIRED CONCRETE

Dong Tran — 2024-10-31

This study focuses on evaluating the electrochemical behavior of steel reinforcement in reinforced concrete structures, particularly those located in marine environments where chloride-induced corrosion is a common problem. The use of patch repair is a popular method for repairing corroded reinforced concrete structures, but improper evaluation of the corrosion cause and extent can lead to rapid deterioration and degradation of the structure. Therefore, it is crucial to monitor the performance of the repaired structure using appropriate methods. The study measures two corrosion parameters, the corrosion potential and the electrical resistivity, to evaluate the effectiveness of the patch repair method. The results show that the patch repair method can significantly affect the performance of the reinforced concrete structure, and the evaluation of the corrosion potential and resistivity distribution is essential to assess the effectiveness of the repair method.

AN ADVANCED ANALYSIS METHOD OF COLPITTS OSCILLATOR CIRCUIT

Bùi Thư Cao — 2024-10-31

Oscillator circuit is one of the most important components in communication devices. Although oscillator circuits have been used more popularly in practical, their analysis theory is still not enough accuracy for determining the oscillator frequency at high-frequency region. In basic, there are two basic parts of an oscillator circuit, an amplifier, and a feedback circuit. In recent analysis methods, the oscillator frequency was defined mostly based on L and C elements in the feedback circuit while these parasitic capacitances between the junctions of BJT transistors in high-frequency domain were nearly omitted. This creates a larger difference for analyzing and designing oscillator circuits at a predefined frequency in high-frequency region. This paper proposed an advanced analysis method which includes all parasitic capacities to increase the accuracy of determining the oscillator frequency of Colpitts oscillator circuit

SILICON NANOWIRE FIELD EFFECT TRANSISTOR AND CURRENT-VOLTAGE CHARACTERISTICS OF THE DEVICE

Nguyễn Văn An — 2024-10-31

Nanowire Field Effect Transistors (NW-FETs) have been one of the most exciting research topics, attracting special attention from scientists worldwide. Many recent studies demonstrate that these devices exhibit excellent electromechanical properties and can be used for manufacturing the next-generation integrated circuits (ICs). This paper presents a model of an NW-FET, consisting of a silicon nanowire placed in the channel to enhance conduction efficiency and mitigate the short-channel effects. A novel approach in this research involves the utilization of the Schrödinger-Poisson equation and the Non-equilibrium Green’s Function (NEGF) method to calculate current-voltage characteristics in the component. Subsequently, the calculated results are simulated using Matlab software with various parameters such as channel length, semiconductor doping concentration, and gate oxide thickness, etc. The experiments indicate that the proposed method gives us accurate results and can be applied to other nanoscale devices.

IMPACT OF DEFAULT RISK IN THE REAL ESTATE SECTOR ON BANK PROFITABILITY AND STABILITY: EVIDENCE FROM VIETNAM

Phượng Nguyễn Thị Mỹ — 2024-10-31

This study investigates the impact of real estate sector default risk on the profitability and financial stability of Vietnamese commercial banks in the period 2010-2023. The author uses an integration of three approaches including panel data estimates by POLS, FEM, REM, 2S-GMM; Quantile regression, PVAR & Granger causality test and Zmijewski X-SCORE model to measure default risk in the real estate sector. The results show that default risk in the real estate sector has a negative impact on bank profitability and stability, but the impact varies across different quantiles. Besides, the findings also show that bank profitability and stability have a positive and two-way causal relationship. In addition, bank-specific and macroeconomic control variables all have an impact on bank profitability and/or stability in the general regression function as well as all quantiles considered. Our findings have important implications for business managers, bank managers and policymakers.

STRENGTHENING TRAINING PROFESSIONAL ETHICS IN ACCOUNTING - AUDITING AT BACHELOR LEVEL IN VIETNAMESE UNIVERSITIES

Tandung Huynh — 2024-10-31

The research goal of identifying factors influencing the enhancement of professional ethics education in accounting and auditing for undergraduate students at Vietnamese universities, this study analyzes and measures the impact of each factor. The study utilizes a mixed method approach, including qualitative research and expert interviews, to establish the research model, questionnaire, and formal measurement scale for quantitative research. The expert interviews have resulted in the elimination of certain measurement scales and the introduction of new ones to improve the questionnaire and research model. The research model consists of five independent factors: information technology, training programs, legal regulations, ethical awareness, and university characteristics, with one dependent factor being professional ethics education in accounting and auditing for students. Based on the research model, the authors will conduct surveys and collect data for analysis using statistical software. Research results show that there are 5 factors that impact in the same direction to help enhance professional ethics education in accounting and auditing: ¹ ethical awareness, ² training programs, ³ legal regulations, ⁴ university characteristics, ⁵ information technology. The level of impact of each factor and policy implications are presented by the author in the research article.

FABRICATION OF SELF-CLEANING GLASS BY ZnO@rGO PHOTOCATALYTIC THIN FILM ONRIENTED 1D NANOROD ARRAY ON THE GLASS SUBSTRATE.

KHUE THANH VAN — 2024-10-31

In this study, crystal nanorod array ZnO@rGO thin film on the glass substrate was synthesized via hydrothermal and nuclei crystalline implant method. According to this, ZnO crystalline nanorod arrays were first grown onto the glass substrate. And then, to improve the applicable performance of the film, rGO material which subsequently anchor to the ZnO film was synthesized by using the modified Hummer’s method. The as-synthesized crystal nanorod array ZnO@rGO thin film oriented on the glass substrate one dimension (1D) was characterized by physical chemical techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM). Performance of the film applied in the photocatalytic reaction through methylene blue degradation that was evaluated by the UV-Vis. As the results, the ZnO@rGO film is oriented on the glass substrate as 1D and well-array as well with 50 nm in diameter, around 1-2 µm and wurtzite cryatal. The XRD and TEM results reveal the evidents of the composited ZnO@rGO film formed on the glass substrate. On the other hand, the UV-Vis analysis shows the MB degradation reaction photocatalytic performance of the ZnO@rGO film is dominated as comparing with the ZnO and ZnO@GO one.

IMPROVEMENT OF INDOMETHACIN-INDUCED GASTRIC MUCOSAL DAMAGE IN MICE (Mus musculus) BY ETHANOL EXTRACT FROM Oldenlandia capitellata Kunzte. LEAVES

Nhung Thi Phuong Tran — 2024-10-31

Gastric ulcer is a significant public health issue worldwide and is associated with various serious complications. Long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) causes gastric mucosal damage and ulceration. In Vietnam, Oldenlandia capitellata K. leaves are widely used in traditional medicine for the treatment of gastric ulcers. This study aimed to determine the effect of ethanol extract from O. capitellata (EOCK) on improving gastric mucosal damage in indomethacin (IND)-induced gastric inflammation in mice. Swiss albino mice were divided into six groups (each group consisting of 5 mice). The groups included the normal control group treated with distilled water, the gastric ulcer control group (negative control) treated with IND (45 mg/kg), the positive control group treated with omeprazole (OME) (20 mg/kg), and the experimental groups treated with different doses of EOCK (200, 250, and 300 mg/kg). Thirty minutes after the administration of distilled water, OME, and EOCK, mice were induced with acute gastric ulceration by exposure to IND. The intervention with EOCK and OME continued for 21 consecutive days. Pretreatment with EOCK reduced gastric mucosal damage, ulcer index, pH, and acid content. The clinical manifestation of gastric mucosal improvement by EOCK included a significant increase SOD, GPx, GSH, TAC, IL-10 levels, and a decrease in TNF-α, IL-1β levels. Histopathological examination showed a noticeable reduction in congestion and leukocyte infiltration in the submucosal layer. Ethanol extract from O. capitellata leaves demonstrated a protective effect on the stomach in mice with IND-induced gastric ulcers. The current study contributes to the development of rational plant-based chemical options for improving gastric mucosal damage caused by chemical agents.

Article Development of a Control-Indicating System for the Constant Volume Combustion Chamber

Chau Tan Vo — 2024-10-31

Researching the optimization of the combustion process using the Constant Volume Combustion Chamber (CVCC) system is one of the effective methods for investigating the influencing factors on the combustion process and the formation of exhaust gases from the fuel utilized in internal combustion engines. This research focuses on developing control algorithms for the CVCC system based on synchronized signals from spark plugs, dynamic pressure sensors, fuel injectors, and real-time data logging to adjust the air-fuel mixture ratio (C₂H₂, N₂, O₂) in order to create operating conditions similar to the late compression stage in diesel engines and simulate exhaust gas recirculation. The three oxygen concentrations after premixed combustion (ignition) of 21%, 15%, and 10% were selected for experimentation in the CVCC system before the diesel fuel injection phase begins at an initial mixture pressure of 14 bar. The results indicate that the system has effectively controlled and recorded data with a high level of accuracy, an observed deviation of 2.24% was found when analyzing the values of maximum combustion pressure after ignition at the experimental oxygen concentrations. Additionally, the electronic systems fully adhere to the trigger signals and the calculated time control signals to determine the air-fuel ratio accurately.

AN EFFICIENT RESPONSE SURFACE TECHNIQUE FOR SENSITIVITY ESTIMATION IN STRUCTURAL RELIABILITY ANALYSIS

Châu Minh Quang — 2024-10-31

The RSM is a powerful structural reliability method using the values of the function at specific points that approximates the limit state function with a polynomial expression. The analytical function replaces the exact limit state function which the computational time required for the assessment of the reliability of structural systems can be reduced significantly. However, the location of the sample points has been investigated by several authors and the performance of the response surface method is still under discussion. Therefore, this study proposes a new response surface method for sensitivity estimation of parameters in structural reliability analysis. A first oder polynomial without cross terms is adopted to approximate the limit-state function, and the sensitivity vector of the limit state function can be obtained. A experimental design with 4n+1 sampling points includes 2n+1 sampling points are chosen along the coordinate axes of the U-space of standard normal random variables, as in the classic RSM and 2n sampling points is rotated according to the sensitivity vector of the limit state function is built. A quadratic polynomial is adopted to approximate the limit-state function, and the most probable point (MPP) can be obtained by conducting HL-RF algorithm based on the created RS. To further improve the precision of reliability analysis, Monte Carlo Simulation (MCS) is conducted on the established polynomial to compute the probability of failure. Three numerical models are considered to demonstrate the advantages of the proposed method.

DESIGN A TRANSMISSION MECHANISM OF ASSISTANT DEVICE FOR STAIR-CLIMBING WHEELCHAIR

Võ Ngọc Yến Phương — 2024-11-01

As known, it is difficult for the disability and the elders to operate the wheelchair moving up and down stairs. Therefore, design and manufacture a transmission mechanism of the assistant device for stair-climbing wheelchair is necessary. In this paper, the work will present a method how to do this task. The transmission mechanism is designed to separate from the wheelchair, which is compact as well as easy to remove, only needing one person to support. e stress of the material. An experimental system is presented to determine the operability of the device.

ACHIEVEMENTS, LIMITATIONS, AND SOLUTIONS FOR BUILDING A TEAM OF OFFICERS AND CIVIL SERVANTS IN HO CHI MINH CITY CURRENTLY

Đặng Thị Minh Phượng — 2024-10-31

Since 1986, together with the Party, the Government, and the people of Ho Chi Minh City in general, many generations of officials, civil servants, and employees, particularly in Ho Chi Minh City, have gradually built a modern and civilized urban area, becoming one of the leading economic, financial, and commercial centers in Vietnam, known for its "cultural, scientific and technological innovation, creativity, education, and training". Specifically in the economic field, the growth or temporary decline of the city's economy has significant impacts on the national macroeconomic situation. Due to the impacts of numerous subjective and objective factors, in 2021, the city experienced a negative growth rate of 6.78% in the economic sector. Facing challenges and difficulties, by the beginning of 2024, the city has managed to “halt” the downward trend and maintain economic growth with a growth rate of 5.81%. The achievements of Ho Chi Minh City in recent years are attributed to the collective efforts and solidarity of the Party, the Government, and the people, particularly the dedicated efforts of the city's officials and civil servants in implementing, concretizing, and creatively applying the Party's and the State's viewpoints and policies into practice, in line with the city's unique characteristics. Throughout the process of building and developing the city, the Ho Chi Minh City Party Committee has always prioritized training, nurturing, and employing a team of politically competent, reputable, and capable officials and civil servants with a spirit of innovation, daring to think and act, and readiness to face difficulties and challenges. However, currently, there is a situation within the city's cadre of officials and civil servants where a portion of them exhibit tendencies to “work cautiously”, “avoid responsibilities”, “fear making mistakes”, etc., when carrying out their duties. The article focuses on clarifying some achievements and limitations of the Ho Chi Minh City Party Committee regarding cadre and cadre work. From there, it proposes solutions to build a dynamic and innovative cadre and civil servant team, working for the common interest and aiming for the goal by 2030: “Ho Chi Minh City becomes a civilized, modern, compassionate, dynamic, and creative city with a high-quality workforce”.

Keywords. Communist Party of Vietnam, The resolution number 98/2023/QH15, Ho Chi Minh City, officers, civil servants, human resources.

INTEGRATING EDUCATIONAL TECHNOLOGY TOOLS IN TEACHING ENGLISH SPEAKING SKILLS: A STUDY ON INSTRUCTOR’S PERSPECTIVES AT A UNIVERSITY IN HO CHI MINH CITY

Nguyen Xuan Hong — 2024-10-31

This study investigates instructors’ perspectives on integrating educational technology (ed-tech) tools in teaching English-speaking skills to students majoring in English at a Vietnamese university. With the prominence of applying technology in teaching and learning at the tertiary level, it is crucial to explore teachers' perceptions of this tendency. Quantitative and qualitative data from closed and open-ended questionnaires were comprehensively analyzed to explore teachers’ responses to the integration of ed-tech tools in speaking instruction. The findings revealed instructors’ support for applying technological tools in teaching English speaking skills, especially for engaging students in the pre-speaking stage. However, due to the limited class time and the large class sizes, those tools should be encouraged as a supplement for self-directed learning activities. The study underlines the critical need for comprehensive digital literacy initiatives and facility upgrades to optimize the impact of technology integration on learning outcomes. Furthermore, it proposes directions for future research, including the exploration and evaluation of more effective ed-tech tools specifically designed to cultivate English-speaking skills.