NKRAFA JOURNAL OF SCIENCE AND TECHNOLOGY

Editorial Note

2024-06-30T15:10:16+07:00

Design and Aerodynamic Analysis of Vertical Take-Off and Landing Solar Powered UAV

2024-02-07T11:13:52+07:00

This paper presents a conceptual design process for designing and improving the M Solar-X fixed-wing solar-powered unmanned aerial vehicle to have vertical take-off and landing capability (VTOL). The separate lift and thrust vertical take-off and landing is selected for design system. The proposed conceptual design process is simple and not complicated because this type of vertical take-off and landing system has a forward propulsion system and a vertical take-off and landing propulsion system. The function areas of these propulsion systems are clearly separated. In addition, the process of analyzing aerodynamic characteristics using Computational Fluid Dynamics (CFD) is introduced into the design process to verify and validate the design principles. Results from the design process found that the M Solar - X VTOL has a final total weight of 18.9 kilograms, which is an increase of 57.5 percent from the original (fixed-wing). In addition, from the aerodynamic analysis, it is found that vertical take-off and landing propulsion systems installed on fixed wing unmanned aerial vehicles have slightly effect on the lift coefficient, while it will significantly affect the drag coefficient (approximately 20 percent higher at all angles of attack). From the results of preliminary aircraft performance calculations, it is found that the vertical take-off and landing of the solar-powered unmanned aerial vehicle (M Solar-X VTOL) has a stall speed of 13.4 m/s. And the maximum flight endurance performance is 2.21 hours or 2 hours 13 minutes, which satisfy the mission requirements.

Determination of Order Quantity by Application of EOQ and Silver Meal Theory Case Study of Wholesale Company in Nakhon Pathom Province.

2024-04-23T07:45:10+07:00

This research is a study of order quantity determination by applying EOQ and Silver Meal theory case study of wholesale company in Nakhon Pathom province. The objectives of this research were 1) to determine the order quantity using EOQ and Silver Meal theory and 2) to reduction of inventory costs using EOQ and Silver Meal theory. This research population includes the total number of employees of the company 19 people. The sample consisted of 7 people using the method of selecting a purposive sample. All data used in this research are secondary data. From August 2023 – September 2023. The research steps are 1) finding a list of problem products 2) finding the cost of ordering per time 3) finding the coefficient of variation 4) finding the order quantity using EOQ theory and Silver Meal 5. ) Comparison of inventory costs before and after using EOQ and Silver Meal theory. The results of the research showed that:

1. The result of the study of order quantity using EOQ and Silver Meal theory found that there were 21 products that were suitable for using the EOQ theory and 4 products that were suitable for using the Silver Meal theory. When all products were taken to find the quantity, the total order quantity was 13,646 units, which was higher than the theoretical order quantity of 3,362 units.
2. The result of reducing inventory costs using EOQ and Silver Meal theory. From calculating inventory costs before using EOQ and Silver Meal theories equal to 583,555.13 baht and inventory costs and after using EOQ and Silver Meal theories equal to 126,167.06 baht. Therefore, inventory costs decreased by 457,388.06 baht, accounting for 78.38 percent.

Concrete of low cost mixed with used EPS foam replaced some fine aggregate for construction

2024-01-25T13:23:25+07:00

The purpose of this research is to study the efficiency of concrete of low cost that mixed with used ESP foam replaced some fine aggregate for construction, comparing with typical concrete and assessment for cost of concrete mixed with used ESP foam. The testing of compressive strength compared with typical concrete and concrete which mixed with EPS foam in rate of 0.03%, 0.05%, 0.07%, 0.1%, 0.2%, and 0.3% by weight of fine aggregates and the curing age of 7,14 and 28 days. The results have shown that increased EPS foam the lower the strength compare to typical concrete. The proper percentage of EPS foam is no more than 0.1 % by weight, average strength of 220 kg/cm2 and average density of concrete is 1%-3% lower than density of typical concrete. The cost of concrete is around 2,001 baths per cubic meter which is 2% lower than typical concrete.

Factors Influencing COVID-19 Medicine Purchasing Decision Behavior: A Case Study of Model Government Hospitals

2024-03-21T08:31:18+07:00

The objectives of this study were to study marketing factors influencing COVID-19 medicine purchasing decision behavior (Case study government hospitals). The sample group includes 400 people who have decision-making power to purchase pharmaceutical products in government hospitals. The instrument used in the study was the 5Ps marketing mix factors, namely Product, Price, Place, Promotion, and People and Conjoint Analysis Method. According to the study's findings, the marketing factor that has the greatest effect on decision-making behavior in purchasing medical supplies to treat COVID-19 is Product factor at 35.04%, followed by the Place factor at 17.95%, the People factor at 17.59%, the Price factor at 15.70%, and the Promotion factor at 13.27%, respectively.

Research and Development of Satellite Engineering Model to Analyze the Attitude Determination and Control System

2024-03-08T07:38:30+07:00

The objectives of the research and development of satellite engineering model to analyze the attitude determination and control system are to study the relevant knowledge in the construction of a 3U satellite engineering model consisting of the structure of the satellite engineering model, command and data handling system (CDHS), electrical power system (EPS) and attitude determination and control system (ADCS). The system interoperability is designed and built into a satellite engineering model focusing on the analysis of the satellite's attitude determination and control system by considering the installation of 3 EA Magnetorquer devices and 1 EA Reaction Wheel. The results of this research resulted in the knowledge of satellite engineering model design and a 3U satellite engineering model, which includes a feature subsystem of design along with being able to pass interoperability testing, Hardware in the Loop testing developed and built a computational program for the analysis of the attitude determination and control system and testing under real environment simulation with Helmholtz Cage that can contribute study findings to future knowledge development and expansion.

Efficiency Enhancing of Reporting Operational Issues via Line Message API

2024-02-06T09:35:32+07:00

The purposes of this research study are as follows: 1) to design and develop the problem report system though the Line application and 2) to facilitate all public officers and workers to live and work in Navaminda Kasatriyadhiraj Royal Air Force Academy by using Line Message API to write automatic chatbot program with the geographic information system (GIS). The satisfactions towards the system were evaluated in four aspects: requirements, correctness, simplicity and stability. The average satisfaction was 4.64. The standard deviation was 0.51. These showed that the system met the good criteria.

Effect of solvent on flexural properties and enhanced tensile properties of composite carbon black reinforced epoxy resin

2024-03-08T08:24:39+07:00

In the 20th century, epoxy resins have found great applications that are widely used in everyday life with the carbon group reinforcing to have better mechanical properties. In this research, we studied the mechanical properties of epoxy composites reinforced with carbon black composite materials. The main objective is to study the effect of solvents on the flexural properties of epoxy resin and tensile properties of epoxy composite materials reinforced carbon black. The results of the study found that 4 different polarity solvents that are ethanol (EtOH), Methanol, MeOH), Acetone and Methyl Ethyl Ketone (MEK) in 1 wt.% had no effect on the stress, Young's modulus, and stress at yield point in flexural property of epoxy resin. In addition, the composite materials reinforced with carbon black in 0.05, 0.2, 0.3, 0.4, and 1 wt.% affect the tensile properties. The composite materials reinforced with 0.3 wt.% of carbon black increase the stress at yield point to 33%.

Introducing Climb-Cruise

2024-03-08T08:29:17+07:00

A climb-cruise is a straight climb with objectives to gain altitude, as well as ground distance. Climb-cruise performance is compared with traditional flight profile consisting of a separate climb and a cruise between the same starting and end points. The flight mechanic analysis of climb-cruise is presented. Examples of performance comparisons between climb-cruse and traditional climb and cruise for 3 example aircraft types are shown. Minimum fuel climb-cruise is the focus of this study, therefore positive fuel saving and time saving are presented to show that climb-cruise is superior over traditional climb and cruise profile.

Selecting transportation modes by the Analytical Hierarchical Process (AHP): A case study of safety glass manufacturer company

2024-05-25T18:54:44+07:00

This research examines cost reduction in logistics by selecting appropriate transportation mode for a case study of a safety glass manufacturer using the Analytic Hierarchy Process (AHP) decision criteria including transportation cost, transportation time, material handling equipment, document management, and product security. From three transportation modes - road, water, and air transport - the study found that road transportation has the highest importance weight at 2.561%. Comparing the costs between the current water transportation and road transportation obtained from the study, the case study company can achieve an average logistics cost reduction of 1,270,000 baht per year, which is 22%.

RC Model Performance Analysis for Airworthiness Certification

2024-05-15T10:00:57+07:00

Military UAV design and production must follow STANAG 4703 which is the Airworthiness for small UAV its weight less than 150 kilogram. This regulation is well-known and being used in various industry. In general takeoff distance is a critical phase of any aircraft because speed of the aircraft is near stall speed. Thus, to get the airworthiness of the aircraft, developer needs to make sure that their design can meet the requirements. The pre-calculation of this data is crucial to avoid unnecessary damage and STANAG allow to get this data from trustable program. Therefore, this research develops a MATLAB calculation using muti-step numerical analysis to calculate takeoff performance of the aircraft. This program has been tested to 4 aircraft compose of 2 general aircraft and 2 mini-UAV. The error of the result is less than 10%. Hence, we can use this program to calculate any other aircraft to get takeoff performance for airworthiness.

Integrating Artificial Intelligence (AI) and Artificial General Intelligence (AGI) to Enhance the Cybersecurity System of the Royal Thai Air Force's Cyber Center

2024-06-06T09:48:17+07:00

This academic article discusses strategies to enhance the efficiency of Air Force Cyber Centers in safeguarding against cyber threats to ensure the security of critical data within information systems and to prevent cyber attacks from malicious actors in the future. Initially, it addresses historical and contemporary cyber attacks both domestically and internationally. Subsequently, it explores the application of AI to bolster cybersecurity measures. Finally, the article proposes the utilization of AGI (Artificial General Intelligence) systems in collaboration with Air Force Cyber Centers as a framework for developing cybersecurity standards and defense mechanisms.