Kasetsart Engineering Journal

Group of factors for assessing the development of construction projects in line with the principles of the Sufficiency Economy Philosophy

2023-04-07T15:43:48+07:00

Construction Projects contribute significantly to the development of people's lives. If sufficiency economy philosophy can be used to assess the construction project during development stage, allocation of budget can be more efficient. The study aims to factor analyzed construction project development indicators in accordance with the sufficiency economy philosophy. Data was collected through interview with questionnaire with 138 engineers in Thai construction industry. The results revealed that the 38 initial indicators were divided into 7 groups: Group 1 Accurate problem identification focusing on the underprivileged group with 7 factors, Group 2 Securing economy necessity for the underprivileged group with 10 factors, Group 3 Sincere mitigation of development impact with 4 factors, Group 4 Maximize utilities through comprehensive consideration with 6 factors, Group 5 Extended value of development to a sustainable community with 4 factors, Group 6 Systematically alternatives develop with comprehensive knowledge with 4 factors, and Group 7 Strong teamwork and team spirit with 3 factors. The total variance explained is 61.860%. The respondents emphasized most on Sincere mitigation of development impact (4.23). However, they do not give importance as much on Securing economy necessity for the underprivileged group (3.65) and Extended value of development to a sustainable community (3.23) especially on solving underprivileged group’s problems of making a living (3.23) and also developing the project knowledge for local people to understand and further extend the project benefits (2.75).

The relationship between groups of factors for assessing the development of construction projects in accordance with the Sufficiency Economy Philosophy influencing people's quality of life enhancement

2023-04-25T11:35:53+07:00

The purpose of this article is to study the relationship of a group of factors in the development of a construction project in accordance with the philosophy of sufficiency economy influencing on enhancing people's quality of life in accordance with the Sustainable Development Goal 17 (SDG17). The quantitative research was conducted by collecting data with a Likert scale at 5 levels from 138 engineers working on construction projects with over 5 years of work experience in public sectors, private sectors, and state enterprises. Then statistical data were analyzed by multiple regression analysis using a group of factors consisting of 7 independent variables and 4 dependent variables. The result found that there were only 5 groups of factors directly related to enhancing people's quality of life and the remaining two groups of factors were not directly related to enhancing people's quality of life. These two groups of factors will lead to a relationship that relies on the mediator variable, which is in accordance with the theory of the relationship of the sufficiency economy philosophy. The relationship concluded from this study can be analyzed in further research. This will enable the development of construction projects to proceed efficiently and in accordance with the sufficiency economy philosophy which will lead to long-term sustainability. As a result, the people in the country will be able to take full advantage of the developed projects and get the most benefit from the development of construction projects according to future urban expansion.

Interference Effects by the in front obstructing building on Wind Pressure Acting on a Tall Building Using CFD Software

2023-04-05T17:53:45+07:00

The analysis of wind forces acting on a structure using Computational Fluid Dynamics (CFD) techniques is widely used in many countries to determine force and pressure coefficients, building top displacements, base shear and moment, surface pressure around the building, etc. This research was conducted using the CFD technique to study the wind effects on a tall building model according to the CARRC (Commonwealth Advisory Aeronautical Council) standard, including building responses in the along-wind and across-wind directions, to verify the applied software and analysis results. Additionally, the interference effects of an obstructing building on wind pressure acting on a tall building were studied. However, in Thailand, wind tunnel experiments are typically used to determine wind force acting on a building model, which is complex and requires expensive instruments. Furthermore, the wind tunnel test is not flexible for adjusting the model to study different experimental conditions and parameters. The accuracy of the analysis was verified by comparing the simulated results of a CFD model software with the results from wind tunnel experimental results of previous research. It was found that the pressure and force coefficients at the location of two-thirds height of the building were slightly different from the experimental results, about 7% and 11%, respectively. Nonetheless, the simulation results can be concluded to be in accordance with the vibration at the top of the building in both along-wind and across-wind directions. Regarding the study of interference effects by the obstructing building, it was found that, with the obstruct distance, u, less than 20, the closer the obstructing building was, the smaller the base shear of the main building could be observed. The same interference effect for the base moment of the main building can be observed since the reduced obstructing distance, u = x/L, is less than 17. Finally, a manual for performing CFD analysis using CFD commercial software for studying wind effects on a tall building has been prepared for further research. It is noted that the computer's performance is an important factor for the CFD analysis. With higher computer performance, more accurate simulation results and faster computation can be obtained.

Interference Effects of Double buildings on Wind Pressure Acting on a Tall Building Using CFD Software

2023-06-12T09:12:14+07:00

There are only few studies of wind load using Computational Fluid Dynamics (CFD) to investigate interference affects on wind pressure acting on a tall building, and mostly only a single obstructing building is considered. Moreover studies of interference effects on base shear and base moment caused by wind are very rare. although they are practically main building design parameters. therefore, this research has been conducted to study interference effects of the in front obstructing double buildings on wind pressure acting on a tall building. The main concerned parameters consist of distance and position of those obstructing double buildings. The same size of 2 obstructing buildings (including, size of small, medium and large) are modelled at various distances in front and located symmetry along the horizontal axis perpendicular to the front surface of the main building with the equal space to the length of the main building along wind direction for allowing wind flow passing through to act on the main building and then analyzed suing commercial CFD software. The obtained simulation results of wind pressure and wind forces acting on the main building are used to find the relationship for estimating the base shear and moment acting on the main building. From the study, if the reduced interference distance, u, less than 1, the interference by the obstructing buildings is small about 10%. But when the obstruct distance increases, the interference effects also increase and reach maximum of the reduced obstructing distance about 11. For u larges than 11, the interference effects decrease with the further obstructing distance. For comparison results of the simulation by CFD with the wind tunnel test, the obtained results are quite different since the wind tunnel test consists of more than 2 surrounding buildings and 1 large low rise neighbour building. For the prediction of base shear and moment acting on the main building caused by wind using the interference factors, the estimation gives smaller base shear and moment than those obtained from CFD simulation for about 53% and 56% respectively. And if compares with the wind tunnel test results, the estimation is about 27% and 38% lesser for base shear and moment respectively

The Causes of Construction Delays in Perspective of Civil Engineers

2023-05-18T15:08:21+07:00

The completion date of a construction project is an important consideration used to determine the reasonable price, proper construction techniques and the right competency for selecting contractors. The purpose of this research was to identify the causal factors associated with construction delays by using questionnaire. The opinions were surveyed from the viewpoints of civil engineers who know the details and are directly responsible for the project the most. Civil engineers also have direct work experience that can best reflect various problems that arise. A sample of 110 civil engineers was selected by the purposive sampling method. The top five highest-rated causes of delays were “Labor shortages”, “Lack of financial liquidity of contractors”, “Change orders during the construction”, “Unclear scope and objectives of the work”, and “Contractors do not pay workers or subcontractors”. In addition, the results of the hypothesis testing revealed that differences in construction types and roles in construction organizations where civil engineers work effect on different opinions on the causes of the delay. The results of this research can therefore be used as guidelines for preparations to address delays at the major causes identified from this research before the implementation of the project.

Effect of Stop-hole Arrangement and Diameter on Crack Growth Retardation of Steel Plate under Flexural Loading

2023-06-30T14:15:00+07:00

This paper presents the effects of stop-hole arrangement and diameter (D) of a single stop-drill hole (SDH), double SDH, and crack flank holes (CFH) on the fatigue life extension of steel plate under out-of-plane flexural loading. The effect of stop-hole configurations on fatigue crack retardation was experimentally investigated on six steel plate specimens with a central through-thickness crack and a stress ratio (R) of -1. Finite element models were developed to evaluate the stress intensity factor at crack tips and the stress concentration around SDH. The experimental and analytical results showed that SDH effectively retarded the propagation of fatigue cracks under flexural loading. The finite element models considering crack surface interference provided a reasonable estimate of the stress intensity factor at crack tips and a prediction of the crack growth direction. The stress concentration around stop holes decreased with an increase in D. For the same D, CFH gave the lowest stop-hole stress concentration, which provided the longest fatigue life initiation from the drilled hole, followed by double SDH and single SDH, respectively. The CFH with a distance between the crack tip and center of the drilled holes of -0.25D provided the most significant fatigue crack retardation.

Procurement and Inventory Optimization of a Frozen Durian Manufacturer

2023-07-27T18:29:37+07:00

The aim of this research is to propose a mathematical model for effectively managing the inventory of whole frozen durian as raw materials, with the objective of minimizing logistics costs and formulating the procurement and storage policies of the company. The research commences by investigating logistics processes and supply chains, with a specific focus on the areas of procurement and storage of raw materials, production, and transportation. To accomplish this, an integer programming is developed to solve the problem by optimizing the objective function of minimizing costs. The obtained results are analyzed using CPLEX Studio, and the model's performance is evaluated using historical data while assessing the sensitivity of various parameters. The findings reveal that the raw material expenses constitute a significant portion, accounting for 97.16% of the total costs. Consequently, the model establishes two distinct price ranges: raw materials will be procured for storage if the price falls below 81.50 baht per kilogram, whereas the range of 82-85 baht per kilogram will be considered for production purposes. Subsequently, the raw materials will be stored in external cold storage facilities, with priority given to the first and second facilities, respectively.

Design of A Low-Power Low-Noise Analog Frontend with Electronically Tunable Anti-Aliasing Capability for Electrocardiogram Recording

2023-07-19T09:58:49+07:00

This paper presents the design of a low-power low-noise chopped analog frontend (AFE) for wearable electrocardiogram recording devices. The AFE has an embedded anti-aliasing filter without the need of an additional lowpass filter, which saves the chip area and overall power consumption without significantly increasing the AFE’s input-referred noise. The AFE’s cutoff frequency can be tuned to the minimum value of 200 Hz via electronically tuning a resistance value with the duty-cycle resistance technique. Designed and fabricated in a 180-nm CMOS process, the AFE, operating from a 1.2-V supply voltage and occupying an area of 0.55 mm², provides a gain of 20 V/V, consumes 2.32 µW of power, and exhibits an input-referred noise of 1.6 µV_rmsintegrated from 1-250 Hz.

Economic assessment of commercial bio-lubricant production from vegetable oils

2023-06-01T15:15:11+07:00

Lubricants are essential petroleum products in any industrial production. Therefore, the possibility of bio-lubricant production from vegetable oil to replace petroleum lubricants was studied. The objectives were to construct a process model of the bio-lubricant production from soybean oil and palm fatty acid distillate using the ASPEN Plus program. Then the economic feasibility of the proposed process was assessed. The bio-lubricant production process comprised converting triglyceride to free fatty acid, concentrating unsaturated fatty acid, and molecular modifying of unsaturated fatty acid to ester or bio-lubricant. The economic assessment showed that if 918 kg/hr of soybean oil and 696 kg/hr of palm fatty acid distillate were used as raw material, 1814 kg/hr of bio-lubricant or 2-ethylhexyl ester was produced. According to the profitability calculation, the net present value (NPV) was 12.60, the internal rate of return (IRR) was 15.24%, and the pay-back period was 4 years within 3 months.