Rajamangala University of Technology Srivijaya Research Journal

Lateritic Soil Quality Improvement Using Palm Oil Fuel Ash and Cement for Road Construction

Peerawat Pongchawitkorn — 2024-08-28

This research studied the possibility of using Palm Oil Fuel Ash (POFA) and Portland cement Type 1 to improve the quality of lateritic soil from the Ban Khuan Chong, Namom district, Songkhla province for road construction. The soil was improved by incorporating cement at proportions of 2%, 3%, 4%, and 5% by weight, and by incorporating a mixture of POFA with particle sizes less than 45 microns at proportions of 5%, 10%, and 15% by weight, along with 5% cement. The preliminary and engineering properties of the soil were tested, including chemical composition analysis (XRF) and microstructure analysis using a scanning electron microscope (SEM). The study found that the main components of the laterite soil improved with POFA and cement were SiO2, Al2O3, Fe2O3, CaO and K2O. The soil improved with cement achieved a maximum compressive strength of 24.8 ksc at 5% cement content over a curing period of 28 days. The soil improved with POFA and cement showed an increase in optimum moisture content (OMC) from 9.7% to 11.2%, resulting in a decrease in maximum dry density (MDD) from 1.970 to 1.861 g/cm3. The soil also achieved the maximum compressive strength of 31.1 ksc at a 5% cement mixed with 5% POFA over a curing period of 28 days. The compressive strength decreased with an increase in the amount of POFA. The soil samples improved with cement at all proportions and the soil samples improved with 5% cement and 5% POFA over a curing period of 7 days met the subbase layer requirements for soil-cement subbase according to the Department of Highways standards for road construction. over a curing period of 7 days met the subbase layer requirements for soil-cement subbase according to the Department of Highways standards for road construction.

Development of a Low-Cost Pulsed Vacuum Infrared (PVI) Drying System

Watcharapol Chayaprasert — 2024-08-28

In this study, a low-cost pulsed vacuum infrared (PVI) drying system was developed using locally available parts, allowing interested individuals to build and use it themselves. The ESP32 microcontroller, in conjunction with solenoid valves, infrared lamps and vacuum pumps, monitored and controlled the PVI drying process. The product used for testing the system was sliced lemongrass. The ratios between the time periods of vacuum and atmospheric pressures (t_VP:t_AP pulse ratios) used in the tests were 8:4, 13:4 and 18:4. The specific energy consumption (SEC) of the system, as well as the weight and moisture content of the dried product, were recorded. It was found that the t_VP:t_AP pulse ratio of 8:4 was optimal for drying with the developed system. The dried lemongrass had a final moisture content of less than 11%_d.b. despite having the highest initial moisture content (roughly 55%_d.b.) and the quickest drying time (roughly 180 min). The electrical energy consumption was roughly 0.6 kW×h, and the mean SEC was 0.019 MJ/g_water. The total cost of the parts and materials was 10,450 baht and the payback period was 6.48 years. With the developed system, drying of agricultural products can be done efficiently using PVI. Nevertheless, the drying yield can be increased by increasing the number of trays and volume of the vacuum chamber.

Experimental Investigation on Precast Reinforced Concrete Beams with Deformed Bars Welded to Steel Plates and Embedded at Support Sections under Transverse Point Loads

Chuthong Kongkaew — 2024-08-28

This paper presents an experimental investigation on precast reinforced concrete beams with connections in the form of deformed bars welded to a steel plate and embedded at the support sections, using a four-point loading test. The objectives are to study the mechanical behaviors, failure modes and effects of the embedded length of the deformed bars on the strength of the beams, and to compare the results with those calculated using the EIT 1008-38 RC beam design equations. The beams have a cross section of 0.175 m in width and 0.35 m in depth, with a span of 4.0 m. The beam’s connections were made of steel plates with a cross section of 0.25 m in width, 0.15 m in depth, and 0.02 m in thickness, and were welded to DB16 bars with embedded lengths of 500 (reference beam), 1,000 and 1,500 mm. From the experiments, all of the beams exhibited bilinear behaviors. They behaved linearly elastic up to about 80-90 percent of their maximum load-carrying capacity, and then they behaved non-linearly with a rapid increase in deflection until failure. Under service conditions (at a deflection of L/240), the beams with embedded lengths of 1,000 and 1,500 mm had a load-carrying capacity 4.27 to 17.45% higher than that of the reference beams. The failure modes can be separated into two patterns. The beams exhibited vertical cracks in the concrete at the support sections due to the slip of the steel plate, and then they failed either in flexural failure or diagonal shear failure, in accordance with the experimental design. Finally, when comparing the ratios between the linear elastic load-carrying capacity of the beams from the experiments and that from EIT 1008-38’s equations, the ratios are in the range of 1.70 to 2.86, depending on the embedded length of the deformed bars.

Development of Algorithm for Smart Cricket Farms with Deep Sleep Mode

Accarat Chaoumead — 2024-08-28

Smart farming is an agricultural innovation that has been increasingly applied to modern agriculture because it can increase production efficiency, reduce costs, and control production quality. It can also be used for monitoring environmental control data which is an important variable in plant cultivation. Since the control system is operated 24 hours a day, such applications consume a lot of electricity. Therefore, this research aimed to develop an algorithm that could reduce power consumption by at least 20% for use in a smart farm system without changing or adding equipment from the original smart farm. An improved algorithm was used to control the output from the original smart farm system with an algorithm to monitor changes in inputs such as temperature and humidity over time in each season, in combination with Deep Sleep Mode (DSM). In addition, it was designed to be compatible with database systems and to display web pages through a wireless network browser to monitor the operation in real time. From a 40-day comparative test on electricity usage between the original smart farm system and the developed smart farm system, it was found that the original smart farm system consumed 42.25 kWh of electricity and the proposed smart farm system consumed 21.04 kWh. The electric power consumption of the developed smart farms system decreased by 21.21 kWh, representing a 50.20% reduction compared to the original smart farms system. In addition, crickets raised in both systems showed similar growth. Therefore, it can be concluded that the algorithm developed, when applied to control the operation of the smart farm system, can effectively reduce electricity consumption.

Impact of Anti-stabbing Material Thickness from Ultra-high Molecular Weight Polyethylene Fabric on Penetration Depth

Sasiradee Jantasee — 2024-08-28

The purpose of this research is to investigate the stab-resistant performance of ultra-high molecular weight polyethylene (UHMWPE) fabric molded into a sheet using a hot compression molding process with a thermoplastic resin, referred to as "UPE" in this study. The stab-resistant sheets were layered to the various specified thickness and tested for stab resistance performance using two types of blades: P1, a typical small knife, and S1, a commando-style blade or larger kitchen knife, following the National Institute of Justice (NIJ)-0115.00 standard. Mechanical properties characterizations revealed that the UPE sheet had maximum tensile and tear strengths of 162.50 MPa and 360.74 N/mm, respectively. The minimal thickness that could withstand stabs at E1 (Energy level 1) for both P1 and S1 type blades was 20 layers of UPE, or thickness of 4.8 mm. The E1 is the first energy level of the NIJ stab resistance testing, with an energy of 24 ± 0.50 J. Thus, it is appropriate for use as a stab-resistant material. When UPE was compared to other stab-resistant materials studied, it was discovered that the UPE had lower thickness and areal density than other materials at the same penetration depth. This indicates that the UPE was lighter and thinner than other materials. The light weight and thinness of UPE are significant factors in its development into stab-resistant armor.

Geopolymer from Metakaolin containing Field Para Rubber Latex Coating for Protecting Reinforced Concrete against Corrosion

Abideng Hawa — 2024-08-28

In this study, geopolymers were synthesized from metakaolin containing field Para rubber latex and activated with sodium silicate and sodium hydroxide. The concrete samples were coated with these geopolymers to assess their corrosion resistance. Geopolymers were prepared by substituting metakaolin with field Para rubber latex at weight percentages of 1%, 3%, 5%, and 10%. The concrete specimens were coated with single or double layers of the geopolymers and then cured for 24 hours. Tensile strength and corrosion performance of the steel were evaluated through an accelerated corrosion test with a 12-volt electric current, applied for 8 hours and paused for 8 hours, over a duration of 14 days. Additionally, samples submerged in seawater were tested. The results demonstrated that the samples coated with geopolymers containing 1%, 3%, and 5% natural rubber latex by weight exhibited a significant reduction in corrosion, evident in both single and double-coated specimens. Structural analysis at the micro level was also conducted at the interfacial transition zone between concrete and geopolymers paste.

Effect of Fiber Alignments on the Strength of Bulletproof Armor Plates Produced from Fiberglass Fabrics

Patamaporn Chaikool — 2024-08-28

This research aims to experimentally investigate the impact of fiber orientation on the strength of bulletproof armor made from composite materials, using fiberglass fabrics as reinforcement encased in polyester resin. The fiber orientation of the woven fiberglass sheets was arranged in two configurations: aligned at 0 degrees and alternately arranged at 45 degrees. Tensile and impact tests revealed that armor with fibers arranged at 45 degrees exhibited lower tensile strength but higher impact resistance compared to armor with fibers aligned at 0 degrees. Additionally, the armor plates were tested against .357 Magnum bullets fired from a distance of 5 meters, following the NIJ (National Institute of Justice) Standard-0101.06 for Level II body armor. The Back Face Signature (BFS) was also measured to assess the impact force on the back of the armor upon bullet impact. The results showed that the armor made from 30 layers of woven fiberglass sheets, both aligned at 0 degrees and alternately arranged at 45 degrees, successfully stopped the bullets without penetration. The average deformation depth of the backing material behind the armor was 8 mm and 6.33 mm, respectively, which is within the standard limits.

Heat Transfer Characteristics in a Flow Channel Having a Single Row of Inclined V-Shaped Pins Mounted on the Endwall Surface

Saree Tongchom — 2024-08-28

The objective of this research is to study heat transfer characteristics and thermal performance with a single row of inclined V-shaped pins in a flow channel. The cylindrical pins, each having a diameter of D=10 mm, were mounted on the heat transfer surface in a wind tunnel. The height of the pin was investigated at H=3.2D and H=2D. The pin-to-pin distance was fixed at S_y=2D in the spanwise direction. The effects of pin inclined angle were investigated at θ=30^o, 45^o, 60^o, 90^o, 120^o, 135^o, and 150^o. The temperature distributions on the heat transfer surface were measured by using an infrared camera. Results for the case H/D=2 show that the V-shaped pin inclined angle of θ=30^o, 45^o, 60^o, 120^o, and 135^o could enhance heat transfer downstream of the pin row when compared to the case of vertical pins with =90^o. In the case where H/D=3.2, the heat transfer on the endwall surface with inclined V-shaped pins was poorer than that with vertical pins with =90^o. The pressure drops in cases where H/D=2 and H/D=3.2 were reduced with mounting inclined V-shaped pins when compared to the case of vertical pins with =90^o.

Development and Acceptance of Time Attendance Web Application Using Identity Verification with Picture and Location of Personnel in Private Universities

Pramote Sittijuk — 2024-08-28

This research aims to develop a time attendance web application (TAW) by using identity verification with picture and location in private universities, as well as to study personnel’s acceptance of the TAW. The population consisted of the Head of the Human Resource department and 94 instructors in Phitsanulok University. Data were collected through in-depth interviews and questionnaires, and were statistically analyzed using content analysis, descriptive statistics, and comparable statistics. The developed web application took the form of a responsive web, accessible on both computer and portable devices which was developed with open-source web programing languages: PHP, Java script, and JQuery. It consisted of 3 main functions: identity verification through personnel pictures and geographical location for sign-in and sign-out work attendance points, work-in record, and monthly work attendance summary reports. Overall, the personnel showed a high level of satisfaction with the TAW (x̄=4.46, SD=0.68) and also accepted it at a high level (x̄=4.08, SD=0.63). Personnel of different sexes, ages, and position levels showed varying levels of acceptance of the TAW in both the internal and supplemented factors, with statistical significance at .05.

Digital Platform Development for Local Freshwater Aquaculture Businesses

Apinan Junkorn — 2024-08-28

This research aims to:1) design and develop a digital platform for local freshwater aquaculture businesses, 2) evaluate the digital platform for local freshwater aquaculture businesses based on mobile application standards, and 3) assess user satisfaction. The sample group also included 20 local inland fishermen. The research tools were the digital platform, the digital platform evaluation form based on mobile application standards, and a satisfaction questionnaire. The statistics used in this research are average () and standard deviation (S.D.).The research findings showed that: 1) the digital platform for local freshwater aquaculture businesses is divided into two parts: front-end web applications and back-end web applications, 2) the level of digital platform evaluation results by five experts is high (= 4.32, S.D. = 0.48), and 3) the level of user satisfaction with the digital platform is high (= 4.40, S.D. = 0.78).

The Development of Semantic Thai Herb Knowledge Mining for Treatment

Anupong Sukparseart — 2024-08-28

Using Thai herbs for treating is an alternative medicine that helps take care of people’s preliminary health and relieves them from diseases and symptoms. This is an important topic that leads to operating this research aimed at: 1) creating the ontology and the rules for searching the semantic Thai herb knowledge, 2) developing semantic Thai herb knowledge mining, and 3) assessing the efficiency of extracting Thai herb semantic knowledge and classifying the Thai herbs’ class. The Thai herb knowledge was collected from 100 websites to build an ontology and extract the semantic knowledge using SWRL with natural language processing. The performance is measured in extracting the semantic knowledge and predicting the classification of herb classes using the neural network (NN), the support vector machine (SVM), the K-nearest neighbor (KNN), and the decision tree (DT). The results show that Thai herb ontology was divided into 2 knowledge classes and comprised eight knowledge nodes. SWRL rules were created to extract the knowledge structures identifying the herb data pattern in 3 types: Zingiber montanum, Tiliacora triandra, and Andrographis paniculate. The ML processing on semantic Thai herb knowledge mining consisted of 4 parts: 1) semantic processing on ontology, 2) extracting the knowledge mining, 3) creating the Thai herb dataset, and 4) predicting the results using ML. The results of assessing the semantic Thai herb knowledge retrieval performance using the ontology and the SWRL rules yielded an F-measure value of 94.8%. The NN had the highest accuracy in predicting Thai herb classes at 90.0% and the KNN had the lowest accuracy at 82.2%.

Most Pobable Number-Polymerase Chain Reaction-based Quantification of Escherichia coli O26, O104, O111, and O157 from Thai and Imported Malaysian Beef

Pattamarat Rattanachuay — 2024-08-28

The contamination of Escherichia coli O157 and non-O157 groups in foods has been reported to cause sporadic cases and outbreaks, resulting in significant economic and social losses worldwide. In this study, the prevalence of E. coli O26, O104, O111, and O157 in retail beef samples from either domestic Thai or imported Malaysian sources was investigated and their amounts were quantified using the MPN-PCR approach. Of the 102 samples, E. coli O26, O104, O111, and O157, were found in beef at rates of 57%, 6%, 0%, and 17%, respectively, with serotype O26 showing the highest contamination rate among the sample (P-value < 0.05). Among the positive samples investigated, the lowest MPN/g value were less than 3 for all serotypes, while the highest MPN/g values of E. coli O26, O104, O111, and O157, were 75, 93, < 3, and 27, respectively. Immuno-magnetic separation technique was also employed to confirm the lack of E. coli O111 in beef. The high level of E. coli O157 and non-O157 contamination in beef observed in this study are thought to pose health risks to consumers, making the finding crucial from a public health standpoint.

Study of Morphology, Mycelial Growth and Exopolysaccharides Production of Cordyceps sp. Selected from Several Farms in Central Region of Thailand

Samart Taikhao — 2024-08-28

Cordyceps militaris is an entomopathogenic fungus that can produce high levels of bioactive compounds such as cordycepin, adenosine, and polysaccharides. This research aimed to study mycelial morphology, growth, biomass, and exopolysaccharides production of Cordyceps sp. strains selected from several farms in central Thailand. Eleven samples of Cordyceps sp. were selected from six farms in Thailand. They were isolates CM-Sp01, CM-Sp02, CM-Sp03, CM-Sp04, CM-Sp05, CM-Sp06, CM-Sp07, CM-Sp08, CM-Sp09, CM-Sp10 and CM-Sp11. The hyphae morphology using the slide culture technique and microscopic examination were investigated. The results revealed that all isolates had septate hyphae. A round and an oval shape of conidia at the end of hyphae were also found. However, the size of conidia was different between Cordyceps sp. isolates. In addition, the study of morphology and density of mycelial colony of C. militaris isolates on PDA medium were determined. The results found that vegetative and aerial mycelium in all isolates were white. The isolate CM-Sp02 showed the highest mycelium density. Under determining the growth of mycelial colony by measuring colony diameter on PDA medium, isolate CM-Sp08 showed the highest growth rate (5.06 ± 0.65 mm/day) and length of diameter of mycelial colony (66.12 ± 1.45 mm) after 21 days of cultivation in PDA medium under temperature of 22 ^oC in dark condition. Mycelial biomass and exopolysaccharides in PDB medium were investigated. The result found that isolate CM-Sp08 showed the highest biomass production (55.20 ± 1.65 g/L) and the highest exopolysaccharide content (55.20 ± 1.65 g/L). This indicated that the isolate CM-Sp08 had high potential for growth, biomass production, and exopolysaccharide production.

The Inhibition of Staphylococcus aureus on Cotton Fabrics using Extracts from Andrographis paniculata Stems and Leaves

Sarunya Puakpong — 2024-08-28

Antibacterial activity study of stem and leaves of creat (Andrographis paniculate) extracts on cotton fabric against Staphylococcus aureus included 2 parts. The first, inhibition of creat extracts on S. aureus test by disc diffusion method, circle shape 6 mm paper disc was applied. Results reveal that zone of inhibition (clear zone) diameter at 5%, 10% and 15% creat extracts concentration were 6.5±0.00^b mm, 7.3±0.03^a mm and 7.5±0.00^a mm respectively. And inhibition of cotton fabric dyed with creat extracts on S. aureus test using the disc diffusion method, circle shape 50 mm diameter cotton fabric was applied. Results reveal that zone of inhibition (clear zone) diameter at 5%, 10% and 15% creat extracts concentration in cotton fabric were 54.4±0.03^b mm, 54.6±0.08^b mm and 55.4±0.08^a mm, respectively. Both creat extracts and cotton fabric dyed with creat extracts advocate the inhibition zone (clear zone diameter) more than paper dish and cotton fabric with creat extracts diameters (> 6 mm and > 50 mm). This study showed that creat extracts and cotton fabric dyed with creat extracts were good antibacterial agent against S. aureus.

Product Development of Flakes with Cricket Powder and Its Application in Granola Ball

Palita Maiprasert — 2024-08-28

Cricket powder is an important potential source of alternative protein in the future. This research aims to develop flakes mixed with cricket powder to increase nutritional value and its application in granola ball product. The ratio of wheat flour to cricket powder was studied at 3 levels 90:10, 80:20 and 70:30 compared with the control formula (flakes without cricket powder). The result of physical, chemical quality, and sensory evaluation found that increasing the amount of cricket powder in the flakes, the protein content increased whereas the water activity (a_w) was significantly lower (p≤0.05). The optimum ratio of wheat flour to cricket powder for flakes production was 70:30. Flakes were applied in granola ball products, the effect of the ratio of flakes, coconut flakes and oats at 70:10:20, 60:10:30, 50:20:30, 60:20:20 and 60:15:25 ratios on product qualities were studied. It was found that formulas with a ratio of 60:15:25 gained the highest liking scores in all attributes. The developed granola balls were considered as a source of protein (10.48%) and crude fiber (8.58%). The total energy was 4.36 kcal/g.

Effects of Emulsifier on Texture and Chemical Properties and Emulsion Stability of Pork Sausage Made of Frozen Pork Meat

Warawaran Shimbhanao — 2024-08-28

This study aims to analyze the texture and chemical property changes of emulsion pork sausages made from frozen pork meat after 3 months of storage at -40°C and to improve sausage quality by replacing the meat with various emulsifiers including 10% and 20% soy protein powder, 10% and 20% isolated soy protein, and 10% and 20% egg white powder. The color, texture, emulsion stability, moisture content, protein content, fat content, and microstructure images of the sausage samples were determined. The results showed the measured sausage colors were varied with the type and amount of emulsifier added; however, overall colors were within the same lightness zone. All emulsifiers affected hardness, cohesiveness, chewiness index, but not the springiness index. Using egg white powder led to the highest hardness. The microstructure of sausage samples showed different pore size and numbers, which were consistent with the texture properties. Regarding the chemical properties, it was found that all treatments had a similar amount of water content. Protein content did not change significantly, but a higher amount of protein could be measured when using 20% of soybean protein and white egg powder. Soy protein powder could improve the sausage texture properties when used in amounts greater than 10%. Furthermore, soy protein and egg white powder could improve the emulsion stability in the sausage mixture if used at 10% or higher.

Effect of Package Type on Quality Change of Mooncake during Storage

Kamontip Kanpairo — 2024-08-28

Mooncakes are a popular type of pastry, particularly during the Mid-Autumn Festival. They are considered an auspicious dessert for Chinese people. However, this product tends to deteriorate easily due to the moisture movement from the filling to the outer crust, resulting in a changed texture and rancidity. A study on the shelf life of mooncake products aimed to investigate the effects of three types of packing conditions: 1) packed in polypropylene plastic bags (PP, control), 2) packed in a polypropylene plastic bag containing an oxygen absorber (PP+O₂ absorber), and 3) packed in a nylon-linear low-density polyethylene (nylon-LLDPE) vacuum bags, all stored at room temperature (29 ± 2 °C) for 42 days. The study found that common factors between storage times and packing conditions affected the chemical and microbiological quality of the mooncake products with statistical significance (p<0.05). There was a difference in chemical quality (a_w, moisture content, and TBA) and microbiological quality (total viable count and mold) between mooncakes packed in nylon-LLDPE vacuum bags and those packed in PP bags and PP+O₂ bsorbers bags. The results showed that packing mooncakes in nylon-LLDPE vacuum bags could slow down microbial growth and lipid oxidation. The most suitable storage condition was packing in nylon-LLDPE vacuum bags which resulted in the product having a shelf life of 35 days at room temperature (29 ± 2 °C), while the quality still met the Thai Industrial Standards (TIS 1454/2012).

Improvement of Blood Meal as an Ingredient in Hybrid Catfish (Clarias macrocephalus × Clarias garepinus) Diet

Porntisa Thongsanitkan — 2024-08-28

The purpose of this research was to study nutritional value and digestibility efficiency of quality-improved blood meal using different enzymes, and to develop feed for hybrid catfish using different levels of cow's blood meal. The study comprised hybrid catfish diet containing 0, 2.5, 5 and 7.5% blood meal. The hybrid catfish were fed with all 4 diets, with catfish feeding at 5% of body weight per day, divided into 3 meals. Weighing was conducted to adjust feed intake, and growth data were collected every 2 weeks over 8-week period. It was found that the improved blood meal had better nutritional value and digestibility compared to non-enzymatically fermented blood. Additionally, the hybrid catfish fed with blood meal at all levels had the final weight, weight gain, daily weight gain, feed intake, feed conversion ratio and survival rate equivalent to the control group (P > 0.05). As for the cost of feed production, it was found that the diets containing blood meal had lower costs compared to the control group, at 31.20 ± 1.60, 27.08 ± 0.99, 28.01 ± 3.84 and 25.40 ± 0.83 baht per 1 kg of fish weight, respectively. The hybrid catfish diet containing 7.5% blood meal could reduce feed production costs by 18.59%. Therefore, the inclusion of blood meal in hybrid catfish diet had an effect on growth and survival rate compared to the control group and could reduce the cost of aquatic animal feed production.

Amphibians Diversity along the Stream Line outside Protection Area at Than To District and Betong District, Yala Province

Sitthisak Jantarat — 2024-08-28

The study of amphibian diversity along the stream line outside protection area in Than To District and Betong District, Yala Province. The amphibians were counted using the visual encounter survey method in December 2019, July 2020, and March 2021 at 7.00 pm. – 10.00 pm. In this study, a total of 2 orders, 7 families, and 28 species were recorded: 25 species in Ban Wang Sai village, Than To district, and 21 species in Ban Saho village, Betong district. The Shannon-Wiener diversity index at both study sites was similar (= 2.50). Moreover, the evenness index in Ban Saho village (0.82) was higher than in Ban Wang Sai village (0.78). The frequency of species occurrence in Ban Wang Sai village included 2 common species, 11 moderately common species, and 12 uncommon species. In Ban Saho village, there was 1 common species, 9 moderately common species, 7 uncommon species, and 2 near-threatened (Limnonectes blythii and L. malesianus). Therefore, in conservation, it is necessary to protect species by emphasizing natural or good agricultural practices, reducing land use changes, and limiting the expansion of cultivation areas. This includes reducing the catch of economic species.

Forecasting the Average Monthly Retail Price of Diesel in Bangkok

Warangkhana Riansut — 2024-08-28

This research aims to forecast diesel prices using the average monthly retail diesel prices in Bangkok obtained from the Bank of Thailand website from January 2003 to October 2022, totaling 238 months. The researcher divided the time series into two sets. The first set comprised 235 months from January 2003 to July 2022. It was used to create a forecasting model using four statistical methods, namely, the Box-Jenkins method, Holt’s exponential smoothing method, Brown’s exponential smoothing method, and the damped trend exponential smoothing method. The second set comprised the last 3 months, from August to October 2022. It was used to compare the accuracy of the forecast models based on the lowest mean absolute percentage error (MAPE) and root mean square error (RMSE). The study found that the forecasting model using Holt’s exponential smoothing method was the most accurate, with MAPE = 0.3053 and RMSE = 0.1158. The model was as follows:

where = 1 represented August 2022.