Authors:Suphachai Yordsawad, Natee Suriyanon Pages: 9 - 22 Abstract: This research was conducted as following. First, the research investigated the stress score of civil engineering staff in 56 projects of the department of rural roads which were carried out from July 2020 to December 2020. The results revealed that out of the full score of 100.00 point, the sample group’s average stress score was 50.16 points. The median score was 49.00 point and the lowest and highest scores were 20.00 point and 80.00 point, respectively. Categorizing the sample group according to stress levels showed that the groups with severe stress, high stress, moderate stress, and low stress accounted for 22.80%, 45%, 29.30%, and 2.90%, respectively. Second, the study analyzed the relationship between individual and career factors and stress scores. It appeared that gender, family income, and job positions had a significant relationship with stress scores, at a statistical significance of 0.05. Third, the research created a multiple linear regression model to predict stress scores, for which five individual and career factors were selected for inclusion: having excess income (family income), working as a foreman or a civil engineer, being male (gender), being 41 to 50 years of age (age), and having to work seven days a week (the number of workdays per week). The predicting power of the aforementioned model was at 13.10 %. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Chinnawat Srichat, Dolrerdee Hormdee Pages: 23 - 34 Abstract: At present, Ordinary Portland Cement has been widely used to improve the soil for highway base course. However, cement manufacturing process impacted on the environment. Geopolymer was chosen to replace the Ordinary Portland Cement for soil improvement in this research. This research was aimed to study the effect of wet-dry condition on unconfined compressive strength (UCS) of soil stabilized with Portland cement and fly ash-based geopolymer. Percentage of cement was 5 7 9 and 11 by mass and percentage of fly ash was 10 20 and 30 by mass. NaOH solution of 10 molar and various mix design at different fly ash/akali activator ratio and Na2SiO3/NaOH ratio were used to preparation specimens and cured for 2 7 and 28 days at room temperature. Each mixture was tested for UCS in accordant to the soil cement standard from the Portland Cement Association was used to perform wet-dry condition test. Wet-dry condition test was divided into 2 sets. The first set was used to conduct the UC test after through the process and the second set was determined the durability of the specimens. The results, revealed that the compressive strength of soil cement tended to decrease after processing and the mass loss percentage was 11.06. The unconfined compressive strength (UCS) of soil geopolymer tended to increase after the wet and dry condition and the mass loss percentage was 6.80. It was concluded that soil geopolymer exhibited the performance in withstanding the wet and dry condition better than soil cement. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Atthaphon Phra-khote, Dolrerdee Hormdee Pages: 35 - 48 Abstract: Loess soil in dry conation is easily lost its strength and collapsed when increased its moisture content for a sufficient time. The of objective this research is to study the improvement of the loess soil with bagasse and rice husk ash-based geopolymer material, compared with the standard of Department of Highways dh-s. 204/2556 for soil cement. The unconfined compression test and durability test in term of wet-dry process method were conducted in laboratory. The specimens were prepared as 95% modified compaction with optimum liquid content. For geopolymer, curing temperature of 70, 90 and 110 ๐C were used for 1 day then curing with room temperature up to 2, 7 and 28 days for curing time, respectively. The ratio of sodium silicate and sodium hydroxide of 1:3 is used. The results shown that for 7-day curing time, the maximum compressive strength was obtained from the lower percentage of bagasse ash with rice husk ash, BA10RH5 at the curing temperature of 70๐C but at higher curing temperature, the maximum compressive strength was obtained from the lower percentage of bagasse ash without rice husk ash, BA10 and that compressive strength were more than the compressive strength of soil-cement, SC5. In term of durability, the SC5, BA10-70 and BA10RH5-90 were chosen using wet-dry method. The percentage of loss in SC5 is 11.06% that was more than those of BA10-70 and BA10RH5-90 as 4.57% and 9.05%, respectively. The results of percentage of loss were related to their corresponding compressive strength. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Wuttichai Phudphong, Dolrerdee Hormdee Pages: 49 - 60 Abstract: This research was aimed to improve the loess soil for base course using palm oil fuel ash and granulated blast furnace slag – based geopolymer and compared to the conventional soil cement. The unconfined compression test and wet-dry durability test were performed in laboratory. The ratio cement is 5, 7, 9, and 11 percent by mass with the room temperature curing for 2, 7, and 28 days. Soil geopolymer used palm oil fuel ash of 5 and 10 percent by mass and 5 percent of palm oil fuel ash mixed with 3 percent granulated blast furnace slag by mass. The concentration of sodium hydroxide solution of 10 molars with the ratio of sodium silicate and sodium hydroxide of 1:3 was used as alkali base. The determined curing phase was 2, 7, and 28 days, controlling temperature at 70, 90, and 110 degrees of Celsius at the first day. The results shown that the soil geopolymer using palm oil fuel ash mix granulated blast furnace slag 5 with 3 percent by mass provided higher strength than using palm oil fuel ash 5 percent by mass about 2.8 percent at 70 degrees of Celsius at curing 28 days, and by exhibited higher strength than soil cement used 5 percent about 11.7 percent. In the term of percent weight loss on durability test, geopolymer using palm oil fuel ash with granulated blast furnace slag provided just littlebit more than using palm oil fuel ash as 0.3 percent and less than soil cement used 5 percent is 3.1 percent. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Thanakit Thepumong, Piyapong Chankawee, Thanakorn Chompoorat, Preeda Chaimahawan, Somboon Shaingchin Pages: 61 - 78 Abstract: Nowadays, the global warming is becoming more intense issue for human. Due to daily human activities, greenhouse gases are increased and they affects the global climate change. One of the effects of the global climate change is heavy rainfall events in many regions around the world. As aforesaid, the north of Thailand also confronts this issue, heavy rainfall, for example in 2010, heavy rainfall caused landslide damaging many people lives and property in Pong and Chiang Kham districts of Phayao province. Consequently, this paper aims to study the effect of the climate change causing the heavy rainfall event in Pong and Chiang Kham districts of Phayao province. The general circulation models (GCMs) using statistical minification are utilized for explanation of the future climate exchange in term of daily rainfall. The results were then predicted the rainfall and heavy rainfall occurrence in the future by comparing with the real observation data from meteorological station in the past. From this study, the result concluded that the rainfall in Pong district has increased approximately 8.0% - 30.0% during 2012-2098. Also, Chiang Kham district has increased 9.0%-35.0% during 2011-2099. Finally, the results of rainfall from GCMs in the future can be used for being on guard of future flood and landslide in the study area. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Panuwat Janbamroong, Chukait Nitayotan, Supachoke Techaudomtaworn, Aummarin Yampraywong, Pennapa Pirodamonchai Pages: 79 - 90 Abstract: This paper presents the design of a hybrid solar water pump inverter which is an alternative for the use of solar energy as a substitute for electric power. The hybrid solar water pump inverter is a system that uses both electricity and solar energy. Therefore, this system can be used in areas where electricity is not accessible, such as in a farm, garden, or remote area. And in the case of using of electric energy and solar energy together, the hybrid solar water pump inverter can be work all the time as needed and reduce electricity consumption. In the event of a power failure, the hybrid solar water pump can use the solar energy and run continuously without stopping the pump. The designed hybrid solar water pump is developed to be compatible both with 1-phase and 3-phase induction motor pump. It has important functions for using efficiently including Maximum Power Point Tracking (MPPT) for solar panel and Power Factor Correction (PFC) for AC input current. In addition, three power modes can be adjusted as appropriate: Grid mode that uses electricity only, Hybrid mode that uses electricity and solar energy together, and Stand-Alone mode that uses solar energy only. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Chocktawee Suriyawattanasin, Thanansak Theppaya, Warakorn Suwanruengsri, Ukrit Ramchaunchorn Pages: 91 - 100 Abstract: Currently, thermoelectric has been increasingly applied to various cooling equipment. It is commonly used in a small-size refrigeration system or in portable cooler box for cold storage. This research studied power supplies to thermoelectric affecting the cooling performance (COP) in a 17.5 L cooler box without cooling load. In experiment, electric power ranging from 19.3-74.1W was supplied to TEC1-12715 modules while airflow inside cooler box was kept at 32 cfm. A 90 L/h cooling water was circulated through a water block, attached on hot side of thermoelectric, and removed heat via radiator. The results showed that maximum COP was 0.53 occurred at cooling rate (qc) of 8.2 W and input power of 19.3 W. A maximum cooling rate of 18.7 W was achieved at 74.1 W input power, and consequently 0.32 COP. It can be seen that the maximum power input to the thermoelectric was not resulted in the maximum qc and COP concurrently. If optimum cooling rate was required, the thermoelectric modules must be powered in the range of 43.3-58.8 W to keep the lowest temperature in the cooling box by 2.0 ± 0.5 °C. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
Authors:Jutathip Leelathanapiat, Piyaphon Paichit, Orawan Reangsephet, Jitpatima Loysoongnern, Supanwipha Khunwiset, Wannaphon Suriyakat Pages: 101 - 111 Abstract: This study aimed to propose the appropriate forecasting method for sales of Green fishing net 380/18 with trend and seasonal components. In this study, the four methods, including decomposition method, Box-Jenkins method, exponential smoothing adjusted for trend and seasonal variation: Winter’s method, and Grey method, were considered. The mean absolute percentage error was uesd as the criterion for comparing the efficiency of the methods. The results revealed that the appropriate method to predict the Green fishing net 380/18 data is the exponential smoothing adjusted for trend and seasonal variation with multiplication model provide the lowest mean absolute percentage error, having the lowest mean absolute percentage error. PubDate: 2022-03-09 Issue No:Vol. 33, No. 1 (2022)
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