RMUTP Research Journal Sciences and Technology

Poly (ethylene terephthalate) Oligomers as a Stabilizer in Colloidal Silver Nanoparticles Synthesis: Blending in Polyethylene for Antimicrobial Efficiency

Sataporn Komhom — 2024-12-29

Colloidal silver nanoparticles synthesis (CSNPs) with the chemical reduction method obtained the achievement by using PET oligomers as a stabilizer that was oligomerized from the glycolysis reaction of poly (ethylene terephthalate) (PET) and ethylene glycol (EG). The study was conducted by varying the concentration of silver nitrate (AgNO₃) solution, D-glucose, and stabilizer to find the most suitable conditions to control silver nanoparticles (AgNPs) size. Fourier transform infrared spectroscopy (FTIR) exposed oligomers’ functional groups, the same as poly (ethylene terephthalate). The scanning electron microscope (SEM) and atomic force microscopy (AFM) revealed that the smallest size was about 42 nm for high concentration at 0.75 M of AgNO₃solution, 1.00 M of D-glucose, and 1.8%w/w of the PET: EG ratio. When analyzed by an atomic absorption spectrophotometer (AAS), the AgNPs concentration was approximately 71,870 ppm. The antimicrobial efficiency test by the plate count method showed greater than 95% inhibition when using CSNPs at AgNPs concentration of 10 ppm. Furthermore, blending CSNPs in polyethylene pellets and polyethylene sheets at AgNPs concentrations of 200 ppm and 750 ppm, respectively, could provide more than 95% inhibition efficiency.

Selection of Amylase-Producing Filamentous Fungi to Hydrolyze Cassava Starch

Chutima Kaewkrajay — 2024-12-29

Due to the current crisis of increasing petroleum fuel prices and problems concerning global warming, cassava starch is used as a low-cost carbon source for ethanol production. Several studies suggested that fungal amylase could be the biochemical solution for transforming polysaccharides into simple sugar. Therefore, the objective of this study was to investigate and characterize the highly efficient amylase-producing fungal isolates that hydrolyze cassava starch to sugar. The four hundred twenty-one (421) isolates of filamentous fungi were tested for their ability to digest 2% soluble starch using an agar plate assay. Among these 421 isolates, 72 fungal isolates exhibited a clear zone diameter in 7 days. All 72 fungal isolates were also tested for their ability to digest 2% cassava starch on agar plates. Four isolates, including 1-5, 13-3, 21-3, and 5-3, had the largest clear zone sizes (≥ 10 mm). They were identified as Taralomyces macrosporus, Penicillium sp., T. flavus, and Penicillium sp., respectively. The partial sequencing of internally transcribed spacer (ITS) regions was performed for the selected fungal isolate. The resulting T. flavus 21-3 gene sequences were deposited in GenBank under the accession number OQ184710. The sugar liberation was performed in a medium containing 2% cassava starch broth. The results showed that T. flavus 21-3 demonstrated the highest efficiency, with a maximum reducing sugar concentration of 5.14 g L^-1 and an enzyme activity of 0.37 U mL^-1. After 7 days of incubation at 30 ºC and growth in a medium containing cassava starch with a pH of 7.5, the culture exhibited high levels of enzymatic activity. These results implied that T. flavus 21-3 has the ability to produce amylase and could digest cassava starch into sugar, which is advantageous for industrial applications and warrants further research.

The Calculation of Bending Moment in Beam by the Three-Moment Equation for the Design of Trailer Chassis

Sittidech Petcharat — 2024-12-29

For the current design of the chassis of a trailer, the chassis is determined as a simply support beam for ease of estimating the bending moment arising from the payload. However, the value of the bending moment estimated by such method is greater than the actual value. According to this issue, this paper therefore proposes an alternative equation that can be used to more accurately estimate the bending moment in the chassis. The equations are created based on three-moment equation and used to analyze the bending moments and bending stresses that occur in the chassis, presented through a case study. The results obtained from the equations are compared with the results obtained from the finite element (FE) model to confirm the validity of the equations. The comparison results show that the results calculated with the equations created are no more than 5% different from those of the FE model. Therefore, the equations developed in this research are reliable. In addition, the case study shows that the maximum bending moment value calculated with equations in this research was 31.9% less than traditional calculations. When such bending moment value is taken into the consideration for selecting the cross-sectional size of steel for making chassis, it resulted in a 17.9% reduction in the weight of the chassis. Therefore, using the equations developed in this research, the designed chassis has lower weight and production costs compared to traditional designs.

Performance Evaluation of the Three-Phase AC-AC Matrix Converter with Adjusting the Switching Frequencies of the SPWM

Prasopchok Hothongkham — 2024-12-29

This paper presents the direct conversion of the three-phase AC input to the three-phase AC output without the DC Link which the converter is called the Matrix Converter. This converter is using the 9-units of bidirectional switches, IGBT-Power Diode. The converter is converting a constant utility three-phase sinusoidal supply voltage and frequency into a variable output voltage and frequency through alteration of the frequency and modulation index of the SPWM signals used by the converter. A mathematical approach is initially applied to describe the principle of the Matrix Converter. Moreover, the voltage and current waveforms, the efficiencies, the harmonics analysis and the total harmonics distortion (THD) of the output side and input side of the voltage and the current waveforms are observed at several the output frequencies which the switching frequencies of the SPWM are adjusted for the performance evaluation of the converter. The simulation results of this converter are observed by the MATLAB/Simulink program.

Parameter optimization of Artificial Bee Colony Algorithm with Response Surface Methodology

Aphirak Khadwilard — 2024-12-29

The Artificial Bee Colony Algorithm is one of the metaheuristic with excellent performance and simple implementation. But it is well known that a metaheuristic approach is required to optimize the algorithm's parameters. Therefore, this research aims to use the response surface methodology for analyze the optimal level parameters of the artificial bee colony algorithm for continuous variable benchmark problems. To carry out this research, a 3^K factorial experimental design was used, with the design parameters consisting of iteration, number of population, and limit. After that, the experimental table was used to collect data, and the data obtained from the experiments was analyzed by the response surface methodology. From the results of the data analysis, it was found that the main effects resulting from the level change of the three parameters, the interaction effect of the bee population and the limit, and the quadratic model were statistically significant at 0.05 (P-value <0.05). The final step was to run the regression model for finding the parameters that resulted in the best answer. The results of the regression model analysis revealed that the optimum parameters of the Artificial Bee Colony Algorithm to solve continuous variable mathematics functions should be set at iteration, bee population, and limits of 900, 40 and 90, respectively.

A Study of Energy Conservation Guideline for the Duck Farm

Surapong Samleepan — 2024-12-29

The research objectives were to study the energy consumption in a duck farm, and study the guidelines for energy conservation for the duck farm, and analyze the payback period. This research surveyed three sizes of duck farms: a small-size duck farm with 1,000 – 3,000 ducks, a medium-size duck farm with 3,001 – 7,000 ducks, and a large-size duck farm with 7,001-10,000 ducks in Banglen, Nakorn Pathom Province. The survey was implemented from February to May 2022. Results showed that the small, medium, and large duck farms had an average energy consumption of around 226.8, 968.4, and 1,289.1 kWh/month, respectively, and the specific energy consumption per duck was around 82.14, 199.25, and 148.17 W/month respectively. For the study of energy conservation in duck farms, the medium-sized duck farm was studied as a case study. There were two plans for energy conservation in the duck farm: the replacement of fluorescent light bulbs with LED light bulbs and the combination of on-grid solar cell system with LED light bulbs. Results showed that replacing fluorescent light bulbs with LED light bulbs could conserve electric energy around 581.66 kWh/year with a payback period of six months. Moreover, due to the combination of replacing fluorescent light bulbs with LED light bulbs and the 4.95 kW on-grid solar cell system, 7,227 kWh/year of electric energy was conserved with a payback period of 5 and 8.3 years, depending on the installation cost.

Impact on Power Quality When Using Fast Charge Type of Battery Charging Station for Electric Vehicles

Sakhon Woothipatanapan — 2024-12-29

This article presents the impact on power system when operating fast charge type of battery charging stations for electric vehicles. In this work, the data analyzed were obtained from measurements that directly affect the three-phase power system at the input side of the electric vehicle battery charging station. The measured values were root mean square voltage (V_rms), root mean square current (I_rms), the total harmonic distortion of voltage (% THD_V), and the total harmonic distortion of current (% THD_I). To store data will be done since it has not been charged, while starting to charge until the electric vehicle battery is fully charged. The vehicles used for testing belong to the Electricity Generating Authority of Thailand (EGAT), which is an electric powered minibus that uses a 120 kW-h lithium-ion battery. The charging station used for testing also belongs to the Electricity Generating Authority of Thailand, the input voltage is AC 400 V, the output voltage is DC 250 to 750 V, and the plug used for charging is a CCS-Type type 2. Once the data is complete, those data are then used to create a graph to analyze the impact on power system. The results of the data analysis revealed that while operating fast charge type of battery charging station for electric vehicles, there are three main effects on power quality of the power system: voltage effect, harmonic effect and the impact on unbalance of power system.

Impact of Particulate Matter 2.5 During Covid-19 in Bangkok, Thailand

Krit Jedwanna — 2024-12-29

Bangkok is a large city with severe Particulate Matter 2.5 (PM2.5) and traffic congestion problem. In past decades, traffic was the main cause of PM2.5. Due to the Covid-19 pandemic in 2020, Bangkok was in lockdown which substantially decreased traffic volume during that period. In this research, the author studied how this change in Bangkok’s traffic volume affected the concentration of pollution, especially PM2.5. Data were collected from 63 points in Bangkok and on 4 highways during January 2018 to December 2023. The analysis showed that during the lockdown period, the concentrations of PM2.5, NOX, NO2, NO and CO decreased by 14.38%, 12.93%, 18.43%, 2.65% and 5.66%, respectively, while traffic volume decreased by about 40%. However, there was no significant relationship between the concentration of PM2.5 and the decreased traffic volume. Therefore, the results indicated that while the Covid-19 pandemic might have influenced the change in traffic volume, it was not the main cause because the effect of season on PM2.5 outweighed the impact of traffic volume.

Thoracic injury of Motorcyclists from Handlebar under Frontal impact in Thailand

Pananya Chuadamrong — 2024-12-29

Motorcycle accidents can lead to chest injuries that result in high mortality rates among motorcyclists. Among the different types of front collisions involving motorcycles, front chest impact with the side of a four-wheeled vehicle was found to be the most likely cause of severe thoracic injury amoung motorcyclists in this research. The study analyzed information collected in Phuket from October 2021 to May 2022. The most common harmful part and angle of impact were extracted from the analysis of accident simulation. The results from data statistical analysis significantly indicate that the side of a four-wheeler vehicle is the most influential area in causing more severe chest injuries in motorcyclists compared to other sites (P<0.05). Notably, a handlebar is one of the most significant parts that cause thoracic injuries. The most influential area of a four-wheeler vehicle and the common thoracic injury of motorcyclists from the harmful parts were used to investigate the effectiveness of possible protective gear. Thus, a chest protective gear can play a critical role in providing thoracic protection. Therefore, the FE human body models of motorcyclist were simulated under front chest impact based on collected data analysis. As a result, it was found that the 2 cm thick rubber of thoracic protective gear is effective only in a 5^th percentile female's chest from the left-frontal attack case. In addition, the findings of data analysis in this research can be used by policymakers and stakeholders to focus on reducing the impact of four-wheeler vehicle on motorcyclists and developing more effective protective gear to mitigate the severity of chest injuries in motorcycle accidents.

A Study on Effect of Ring on Behavior of Heat Transfer to Pot of KB-5 Cooking Stove by Computational Fluid Dynamics

Pattanapong Kaewpho — 2024-12-29

The objective of this research is to study the effect of the ring on the behavior of heat transfer to the pot of a KB-5 cooking stove by computational fluid dynamics and experiments. The simulation model was using ANSYS 21 in 3D-model. The effect of the ring on heat transfer behavior to the pot was investigated. Heat transfer to the pot of the stove with ring, being Model B and Model C, was compared with the original stove, the stove without ring (Model A), using total heat flux from simulation and thermal efficiency from experiment. In this study, it was found that the total heat flux from simulation and the thermal efficiency from the experiment of two stoves with rings were better than those of stoves without rings. Model C has the highest total heat flux of 24.40 kW/m², followed by Model B and Model A with total heat fluxes of 24.42 and 18.32 kW/m², respectively. Model C and Model B have a total heat flux increase of 24.92 and 14.47%, respectively, compared to Model A. Model C has the highest thermal efficiency of 45.80%, followed by Model B and Model A with thermal efficiency of 42.40 and 39.15%, respectively. Model C and Model B have a thermal efficiency increase of 14.52 and 7.67%, respectively, compared to Model A. Thus, heat transfer to the pot of the stove with a ring (Model C) has the highest performance.

The Development of Caramel Sauce From Palmyra Palm Syrup and Palmyra Palm Powder (Borassus flabellifer L.)

Laddawan Klinmalai — 2024-12-29

The purpose of this research was to develop caramel sauce from palmyra palm syrup and palmyra palm powder. This is to add value to palmyra palm and to develop more variety of sauce products. Three basic formulas of caramel sauce were selected by using palmyra palm syrup instead of sugar, i.e. basic formulas 1, 2, and 3. Then, the basic formula caramel sauce with the highest average sensory quality was added to palmyra palm powder. Three levels of palmyra palm powder, 3%, 4%, and 5%, were analyzed for physical quality, chemical composition, and sensory quality compared to the basic formula of caramel sauce. The study found that in basic caramel sauce No. 2, the tasters gave the highest average sensory quality score. In terms of appearance, color, smell, texture, and overall liking, the values were 7.80 7.87 7.90 7.55, and 7.82, respectively, in the very like level. Basic caramel sauce no. 2 was added to the palmyra palm powder. The 3% palmyra palm powder caramel sauce had physical quality. chemical composition and sensory quality were similar to basic caramel sauce no. 2 with a viscosity of 33.4×104 cent points, lightness (L*) of 46.99, a* of 19.59, and b* of 45.25. The chemical composition shows that energy was 404.40 kcal/100 g, moisture, fat, protein, carbohydrate, fiber, and ash were 334.81%, 30.67%, 2.44%, 25.53%, 5.48%, and 1.07%, respectively. The tasters gave the sensory quality score, in terms of appearance, color, smell, texture, and overall liking, which is not significant from the basic caramel sauce no. 2 at the 0.05 level.

Resuspension of Road Dust from Electric Vehicles under Steady and Real-world Driving Tests

Sirasak Pong-a-mas — 2024-12-29

Internal combustion engines are considered as one of the most important major causes of air pollution. Many countries including Thailand pay attention to this problem and support electric vehicle usages for emission reductions. However, past literatures indicated that electric vehicles also emitted Particulate Matter (PM) via non-exhaust emissions. These included tyre wear, brake wear, road surface wear, and resuspension of road dust. Weight and speed of vehicles were found out as the major variable on this non-exhaust PM emissions. In the current study, non-exhaust PM emissions from an electric vehicle were measured by installing a real-time PM concentration measuring device in the back of the front left wheel while the vehicle was moving. There were three types of tests: constant speed test, ISO 21994:2007 standard brake test, and real-world driving cycle test. In each type of tests, payloads were varied. From the experimental data in all tests, it has been clearly seen that increasing payloads on the tested vehicle resulting in changes in PM emissions. With the same payload, the amounts PM10 emissions increase when the vehicle speeds are varied from 40 to 80 km/hr. However, varying speed do not affect the amounts of PM1 and PM2.5 at the speed of 60 and 80 km/hr. Only the increase of PM10 emissions is observed. In ISO 21994:2007 standard brake test, additional payload of 200 kg results in almost half of PM emissions increase. In the real-world driving test, braking sequences (vehicle was accelerated and stopped) tremendously affects the amount of PM emissions. In addition, the condition of road surface also impacts the amounts of resuspended PM emissions.

Development of Single-use Plate from waste of Sanpatong Seedling

Napat Chantaramee — 2024-12-29

Recently, it has been of great interest involving to mitigate the environmental impact by changing the plant processing waste towards the circular economy concept. This research was aimed to add value to waste from processing of Sanpatong sticky rice seedling. Disposable plate was made from starch foam mixed with waste from processing of Sanpatong sticky rice seedling by compression molding. The content of rice seedling waste was not more than 14 weight percent of starch foam. The compression condition is 170^oC with the pressure of 14 MPa. The area, the thickness, and the density of disposable container are 144cm², 1-2 mm. and 0.20-0.46 g/cm³, respectively. The disposable plate is light and the density does not depend on the content of waste of rice seedling. The flexural strength of disposable plate is about 3.2-3.5 MPa which is lower than that of commercial one. The water adsorption of disposable plate decreased when adding not more than 10wt% of kaolin and latex rubber in starch foam. Coating with polylactic acid on disposable container can also reduce the water adsorption.

Temperature and Relative Humidity Control in a Greenhouse Evaporative Cooling-pad system

Watsapon Junpayap — 2024-12-29

This research aimed to study the control of temperature and relative humidity of the air inside a greenhouse equipped with an evaporative cooling pad system. The control system was divided into 3 systems: The temperature control system at 25°C, the relative humidity control system at 70% RH, and the vapor pressure deficit (VPD) control system at 0.85 kPa. It was found that on a cool day, the temperature control system can maintain an average temperature of about 25°C. However, on a hot day, the system cannot effectively control or reduce the average temperature inside the greenhouse to the required value. Nonetheless, it can successfully control the average temperature inside the greenhouse to be about 5-7°C lower than outside the greenhouse. The relative humidity control system maintained the average relative humidity inside the greenhouse at about 70% RH every day of the test, but the average temperature inside the greenhouse was about 28-35°C. The VPD control system can be maintained at the specified value for some time; it varies according to the temperature and relative humidity of the air. However, the average temperature and relative humidity inside the greenhouse were still within the suitable range for growing plants in the greenhouse. The water and electricity consumption of the system depends mainly on the weather conditions and the operation of the control system. The relative humidity control system consumes the lowest electrical consumption, while the temperature control system has the highest electrical consumption, Therefore, the temperature control system has the highest cost compared with the relative humidity control system and the vapor pressure deficit control system.

Analysis of Important Factors Affecting the Tenure of Professional Technicians in the Organization

Natworapol Rachsiriwatcharabul — 2024-12-29

The purpose of this research is to analyze important factors that affect the tenure of professional Technicians at large automobile centers in the country. Years of employment in an organization are very important as it is one of the factors that can be used to determine employee satisfaction and happiness at work. If the employees have a long working life, then the stability of management and operations will be stable. In addition, it will make it possible to predict operating results as well as reduce the cost of hiring new positions to replace them, and it also reduces the rate of resignation from work. The study of influences affecting the tenure of professional technicians in an organization was conducted with a sample of 245 people. Data were collected by means of a survey using a questionnaire as a tool. Collecting data from samples to analyze the data using quantitative statistics to explain averages, percentages, standard deviations and uses reference statistics such as analysis of variance (One Way ANOVA). In testing personal factors using the Multiple Regression Analysis method to analyze the influence of push factors and attract factors that affect tenure in the organization. The results of the study found that the different personal factors in terms of salary and age have different effects on the tenured of skilled technicians in an organization. As for the personal factors of different educational levels, there is no difference in the effect on the tenured of skilled technicians in an organization. In terms of pushing factors and attracting factors, it was found that they influence the tenure in the organization of skilled technicians at a statistical significance at the 0.05 level. It can be concluded that attracting factors have a greater influence on the tenure of skilled technicians in an organization than pushing factors.

The Performance Comparison of Mean Estimation by Imputation with Auxiliary Variable under Various Missing Data Mechanisms

Nahathai Srakobkaew — 2024-12-29

The objective of this research is to compare the performance of mean estimation when data is missing. Mean estimators are derived from imputation methods, including the mean method, factor method, and exponential method. Under missing data mechanisms, there are 3 types, including missing completely at random, missing at random, and missing not at random. This research uses the small dust particles from the Pollution Control Department's sources to study the efficiency of mean estimation using the imputation method for each situation. The criterion used to compare efficiency is the mean square error. The sample sizes were set to be 30, 100, and 500 at missing data levels of 10%, 20%, and 30%. The results showed that under all types of missing data mechanisms, the efficiency of mean estimation from the imputation method that uses information from an auxiliary variable together with the study variable as the factor method and the exponent method was better than the mean method that uses the study variable only. Moreover, the sample size and the missing data levels affect the performance of the method. As the sample size increases, the efficiency of the method increases. But if the missing data levels increase, the efficiency of the method decreases.