Nakhon Ratchasima, Thailand

Nakhon Ratchasima Rajabhat University
Nakhon Ratchasima, Thailand
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Lin J.-L.,Yuan Ze University | Khomnotai L.,Nakhon Ratchasima Rajabhat University
Entropy | Year: 2017

With a privacy-aware reputation system, an auction website allows the buyer in a transaction to hide his/her identity from the public for privacy protection. However, fraudsters can also take advantage of this buyer-anonymized function to hide the connections between themselves and their accomplices. Traditional fraudster detection methods become useless for detecting such fraudsters because these methods rely on accessing these connections to work effectively. To resolve this problem, we introduce two attributes to quantify the buyer-anonymized activities associated with each user and use them to reinforce the traditional methods. Experimental results on a dataset crawled from an auction website show that the proposed attributes effectively enhance the prediction accuracy for detecting fraudsters, particularly when the proportion of the buyer-anonymized activities in the dataset is large. Because many auction websites have adopted privacy-aware reputation systems, the two proposed attributes should be incorporated into their fraudster detection schemes to combat these fraudulent activities. © 2017 by the authors.

Toboonsung B.,Nakhon Ratchasima Rajabhat University
Key Engineering Materials | Year: 2017

Fe-doped NiO nanoparticles was prepared by the co-precipitation method. The precipitation solution were used the concentration of FeSO4 mixing NiCl2 for 0.5 M. The precipitation process was used a magnetic stirrer of 1100 rpm, a temperature of 30-60 °C for 0.5 h and the dropping a NaOH of 0.5 M in the mixing solution. The precipitate product was dried at the temperature of 120 °C for 9 h and calcined in a furnace at the temperature of 400 °C for 4 h in air atmosphere. The powder product was analyzed a crystal structure by a x-rays diffractometer, calculated an energy band gap by UV-VIS spectrophotometer, measured a magnetic properties by a vibrating sample magnetometer and explained morphology by a scanning electron microscope. It was found that the crystal structure was shown face center cubic. The nanoparticles in the range of 30-100 nm was observed the morphology of the optimum product. However, the coercive, the magnetic moment and the energy band gap was found the optimum at the doping Fe of 8 wt% at the precipitation temperature of 40 °C. © 2017 Trans Tech Publications, Switzerland.

Visutthi M.,Nakhon Ratchasima Rajabhat University
Proceedings 2015 International Conference on Science and Technology, TICST 2015 | Year: 2015

Quorum sensing is an intercellular signaling system in bacteria in response to cell population. Several physiological processes in pathogenesis of medically important bacteria are associated with quorum sensing. As quorum sensing controls bacterial virulences, the inhibition of the system is being considered as a novel approach for antibacterial substance. This research determined the effect of 47 Thai medicinal plant species on bacterial quorum sensing, Chromobacterium violaceum. Anti-quorum sensing activity was indicated by the inhibition of violacein pigment producing of biomonitor strain, C. violaceum DMST 21761. Screening test by disc diffusion assay revealed that five plant extracts exhibited anti-quorum sensing activity including Alpinia galanga Sw., Feronia limonia (L.) Swing, Millingtonia hortensis Linn., Oroxylum indicum (L.) Kurz., and Sesbania grandiflora (L.) Poiret. All extracts, except A. galanga, reduced violacein production. Sixteen extracts produced pronounced inhibitory activity. This result may reveal the mode of action of botanical plants including anti-quorum sensing property and this activity should be further examinations. © 2015 IEEE.

Toboonsung B.,Nakhon Ratchasima Rajabhat University | Singjai P.,Chiang Mai University
Journal of Alloys and Compounds | Year: 2012

A flexible angle sensor was prepared using an electrophoretic co-deposition process to form nanocomposite networks of multi-wall carbon nanotube/cupric oxide/cuprous oxide (MWNT/CuO/Cu 2O) on a polyethylene terephthalate (PET) sheet. The deposition method used copper and stainless steel electrodes, and the effects of varying of electrode separation, MWNT concentration in deionized water, voltage and deposition time were studied. The film resistance of the as-deposited samples decreased with increasing the MWNT concentration up to 0.3 mg/ml. The angle sensor showed a linear relation between the film resistance and the bending angle, a relationship that was illustrated with loop area and sensitivity data. The best angle sensor was successfully made with an electrode separation of 8 mm, a concentration of 0.3 mg/ml, a voltage of 10 V and a deposition time of 3 h, parameters that resulted in a minimum loop area and the most stability in sensitivity over a thousand bending cycles. © 2012 Published by Elsevier B.V.

Sata V.,Khon Kaen University | Sathonsaowaphak A.,Nakhon Ratchasima Rajabhat University | Chindaprasirt P.,Khon Kaen University
Cement and Concrete Composites | Year: 2012

This paper presents an investigation of the compressive strength and the durability of lignite bottom ash geopolymer mortars in 3% sulfuric acid and 5% sodium sulfate solutions. Three finenesses of ground bottom ash viz., fine, medium and coarse bottom ash were used to make geopolymer mortars. Sodium silicate, sodium hydroxide and curing temperature of 75°C for 48 h were used to activate the geopolymerization. The results were compared to those of Portland cement and high volume fly ash mortars. It was found that the fine bottom ash was more reactive and gave geopolymer mortars with higher compressive strengths than those of the coarser fly ashes. All bottom ash geopolymer mortars were less susceptible to the attack by sodium sulfate and sulfuric acid solutions than the traditional Portland cement mortars. © 2012 Elsevier Ltd. All rights reserved.

Phaiboonnugulkij M.,Nakhon Ratchasima Rajabhat University
International Journal of Applied Linguistics and English Literature | Year: 2016

The objectives of this paper were to compare total and individual metacognitive strategies by four groups of university students from different majors in five different tourism situational lessons. The total of 34 students participated in this study, and they were categorized into four groups based on their major of study and English proficiency level. The research instruments were a web-based speaking test in English for Tourism (WBST-EFT), a strategy coding scheme and the Internet-mediated contextualized English for Domestic Tourism lessons (InConMedt). Mixed methods of quantitative and qualitative approaches were employed in the present study. The quantitative analysis included Kruskal Wallis, Mann-Whitney U test as well as Chi-square, mean rank, frequency and percentages. Qualitative content analysis from the verbal reports in the stimulated recall session on metacognitive strategies was employed in this study. The findings showed that four groups significantly and differently employed total metacognitive strategies in five lessons, 2(3, N = 34) = 10.00, p =.01. The significant difference was evident in the use of individual metacognitive strategies including goal setting and planning of the groups and in a particular lesson. The insights from the verbal report content analysis revealed significant information on how the high proficiency group effectively employed their metacognitive strategy in their speaking performances; whereas the information from the low proficiency group also shed more light in the instructional approach on how to train these students to improve their speaking ability using effective strategies. © 2016, Australian International Academic Centre PTY LTD. All rights reserved.

Amornsinlaphachai P.,Nakhon Ratchasima Rajabhat University
2016 8th International Conference on Knowledge and Smart Technology, KST 2016 | Year: 2016

Two purposes of this study are 1) to select a data mining model to predict learners' academic performance in computer programming subject to group learners for cooperative learning by comparing the efficiency of the models created from data mining with classification technique and 2) to develop a model for cooperative learning via web using the selected data mining model to group learners. The efficiency of seven models created from data mining with classification technique by using seven algorithms that are Artificial Neural Network, K-Nearest Neighbor, Naive Bayes, Bayesian Belief Network, JRIP, ID3 and C4.5 is compared and it was found that the models created from C4.5 has the best efficiency. The accuracy of the model created from C4.5 is about 74.8945% and the accuracy tests show that this model is reliable. Therefore this model is selected to group learners with STAD technique for cooperative learning through web. The result also shows that ID3 is inappropriate to predict learners' performance. The data mining model created from C4.5 shows that math's GPA has the most influential for academic performance in computer programming subject. The model for the cooperative learning model via web using C4.5 to group learners consists of 5 components that are data management module, prediction and grouping module, learning resources, cooperative community and quiz module. The results also show that in the case of using the selected model to group learners and in the case of grouping learners by the lecturers, the learning progressive-score in the first case is higher. © 2016 IEEE.

Lin J.-L.,Yuan Ze University | Khomnotai L.,Yuan Ze University | Khomnotai L.,Nakhon Ratchasima Rajabhat University
Entropy | Year: 2014

Online auctions attract not only legitimate businesses trying to sell their products but also fraudsters wishing to commit fraudulent transactions. Consequently, fraudster detection is crucial to ensure the continued success of online auctions. This paper proposes an approach to detect fraudsters based on the concept of neighbor diversity. The neighbor diversity of an auction account quantifies the diversity of all traders that have transactions with this account. Based on four different features of each trader (i.e., the number of received ratings, the number of cancelled transactions, k-core, and the joined date), four measurements of neighbor diversity are proposed to discern fraudsters from legitimate traders. An experiment is conducted using data gathered from a real world auction website. The results show that, although the use of neighbor diversity on k-core or on the joined date shows little or no improvement in detecting fraudsters, both the neighbor diversity on the number of received ratings and the neighbor diversity on the number of cancelled transactions improve classification accuracy, compared to the state-of-the-art methods that use k-core and center weight. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Jittabut P.,Nakhon Ratchasima Rajabhat University
Energy Procedia | Year: 2015

This research was presented the mechanical and thermal properties of cement-based composite for thermal energy storage materials. The effects of nanosilica particle size and concentration determined by mixing three nanosilica particle sizes of 12, 50 and 150 nm, using nanosilica were of 1-5 wt%. Thermal properties coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of nanosilica on the performance, such as compressive strength, bulk density, thermal conductivity, volume heat capacity and thermal diffusivity of hardened composite cement pastes were studied for future solar thermal energy materials with better performance. According to the development of thermal storage materials and their application environment requirement in solar thermal power, the specimens were subjected to heat at 350oC and 900oC. There were observed that, before heating, the compressive strength is optimized at nanosilica amount of 4wt% with nanosilica particle size of 50 nm at the age of 28 days. Moreover, after heating at 350oC and 900oC, the thermal conductivity and volume heat capacity of the cement paste enriched with nanosilica were significantly lesser than that of the before heating one. © 2015 The Authors. Published by Elsevier Ltd.

Jittabut P.,Nakhon Ratchasima Rajabhat University
Energy Procedia | Year: 2015

The physical and thermal properties of the briquette were determined by varying rice straw and sugarcane leaves ratios of 100:0, 80:20, 50:50, 20:80 and 0:100 using molasses as the binding agent. The briquette-molasses to binder ratio of 100:50 was used. Ultimate and proximate analyses were carried out to determine the average composition of their constituents. The physical properties studied included species density, compressive strength and moisture content. Fuel properties were determined using standard laboratory methods. The result was indicated that the density, high heating value, and compressive strength were also tested. Results showed that fixed carbon was 9.06-13.63%, volatile matter was 68.14-74.67%, ash content was 7.84-12.85%, and moisture content was 4.2-6.2%. Results from ultimate analysis showed that the content of C H O N S was follows; 38.6-43.2%, 5.4-6.2%, 34.5-36.4%, 0.27-0.44% and 0.02-0.04%. The high heating value was in the range of 16.3-17.83 MJ/kg. The density was in the range of 0.53-0.58 kg/m3. The compressive strength was in the range of 32.4-44.7 kg/cm2. The briquette from rice straw: sugarcane leaves had optimum ratio at the ratio 50:50. The thermal properties and physicochemical characteristics of these wastes demonstrated that they are potential candidates to produce briquettes as fuel in several applications. © 2015 The Authors. Published by Elsevier Ltd.

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