Science & Technology Asia <p style="text-align: justify;">Science &amp; Technology Asia (formerly Thammasat International Journal of Science and Technology), first published in 1996, is a peer-reviewed, open access journal containing original research articles, review articles, and short communications in the fields associated with science and technology.&nbsp;Science &amp; Technology Asia aims to be a forum through which scientists and experts in the fields of science and technology share and discuss their quality research work. Original research articles as well as review articles and short communications in multidisciplinary fields of science and technology are within the scope of the journal.<br>The journal welcomes contributions in the following fields:<br>1. Physical sciences such as chemistry, physics, mathematics, statistics.<br>2. Engineering such as electrical engineering, chemical engineering, civil engineering, environmental engineering, computer engineering; and information technology.<br>3. Biological sciences such as biology, zoology, botany, genetics, agriculture, ecology.<br>The journal publishes 4 issues per year: No.1 January-March, No.2 April-June, No.3 July-September and No.4 October-December.<br>Science &amp; Technology Asia&nbsp;is currently indexed in both national and international electronic/online databases, namely, Thai-Journal Citation Index (TCI) Tier 1, ASEAN Citation Index (ACI), Elektronische Zeitschriftenbibliothek (EZB).</p> <p style="text-align: justify;">This journal has adopted a double-blind reviewing policy whereby both the referees and author(s) remain anonymous throughout the process.</p> en-US (Wutiphol Sintunavarat) (Thanyarat Jeamklin Thammasat University (Rangsit Campus)) Thu, 28 Jun 2018 00:00:00 +0700 OJS 60 Optimal and Near-Optimal Inventory Policies with Shipping Cost and Planned Backorders <p>This article extends the Economic Order Quantity with backorders (EOQB) model with a mode of oversea shipping cost, namely full container load (FCL), by introducing a constraint of containers’ capacity limitation to the model. Exact algorithm is proposed for straightforwardly solving a single product EOQB with shipping cost. The illustrative examples show that the proposed method yields the optimal solutions without using any complicated mathematical calculations. The model of multi-product EOQB with shipping cost is also presented. It is more complicated than the first one. We make use of the method of Lagrange multipliers to solve it systematically. The acceptable near-optimal solutions can be found; the differences ranges from 0.08-4.96% when compared to those obtained from the Excel solver. However, the second proposed method needs a skilled analyst to solve it on a spreadsheet.</p> Choosak Pornsing ##submission.copyrightStatement## Thu, 28 Jun 2018 00:00:00 +0700 Effects of Intercropping of Marigold and Yardlong Bean on Population of Cowpea Aphid, Aphis Craccivora Koch <p>The experimental field was planted at Pathum Thani Province to assess the effects of marigold and yardlong bean intercropping on a number of cowpea aphids, a number of natural enemies, growth and yield of yardlong bean and insect bio-diversity. The experimental design was a randomized complete block design (RCBD) with four treatments each of which was replicated three times. Each of the 12 plots measured 7 m x 5 m in the experiment. The distance between inter and intra row spacing for all treatments was 70 x 50 cm with 1 m spacing between plots. The intercropping treatments were: sole yardlong bean (T1), 1 row of yardlong bean with 1 row of marigold (T2), 2 rows of yardlong bean with 1 row of marigold (T3) and 3 rows of yardlong bean with 1 row of marigold (T4). The results showed that intercropping yardlong bean with marigold had significant (p&lt;0.05) effect on the number of cowpea aphids, the number of natural enemies, growth and yield of yardlong bean and insect bio-diversity when compared with the sole yardlong bean. The 1 row yardlong bean + 1 row marigold had the lowest number of cowpea aphids from week1 to week6 when compared with other intercropping. The 1 row yardlong bean + 1 row marigold were value with 26.32+1.24, 42.00+0.61, 65.33+1.69, 70.33+1.69, 110.66+1.24 and 145.00+1.63 aphids/ 5 yardlong, ladybird beetles (34.60 + 1.24), black ant (30.80 + 1.24) and spider (17.33 + 0.94), plant height and weight (42.25 + 0.82 cm and 2.75 + 0.82 kg) and insect bio-diversity (1.44). Therefore, intercropping yardlong bean with marigold is an effective practice in the control of cowpea aphids and enhancing insect bio-diversity.</p> Nathapong Matintarangson ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 Concrete Crack Detection Using the Integration of Convolutional Neural Network and Support Vector Machine <p>Crack detection in concrete structures is an important task in the inspection of buildings to ensure their safety and serviceability. Previous studies relating to crack detection via image-processing and machine learning techniques generally involve the complex modelling of cracks and the extraction of hand crafted crack features. This approach often fails to apply to images from a real environment. This paper proposes a new image-based crack detection system using a combined model of classifiers, namely a Convolutional Neural Network (CNN) and a Support Vector Machine (SVM), which was proven to perform better than the methods involving the handcrafted features. In the proposed technique, a CNN is used in extracting deep convolutional features from the RGB images of cracks and an SVM classifier is used as an alternative to a softmax layer to enhance classification ability. The combined model automatically extracts features and determines whether or not an image patch belongs to a crack class. A dataset of 550 images are collected by a digital camera from various locations, and from the results, it is concluded that the proposed method is able to identify cracks on concrete surface with an accuracy of 90.76 %</p> Mayank Sharma, Weerachai Anotaipaiboon, Krisada Chaiyasarn ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 Influence of Whey Protein on Stability of α-Mangostin Entrapped in Alginate/Whey Protein Beads <p>Although encapsulation efficiency of various biopolymers has been documented, no attempts have been made to investigate stability of α-mangostin entrapped and an encapsulation efficiency of biopolymer beads in different conditions. In this study, the efficiency of whey protein (W) and Alginate (A) to encapsulate α-mangostin was assessed through the investigation of the α-mangostin content stored at different conditions. Particle size and stiffness of biopolymer beads were measured. An increase in whey protein content enhanced gel viscosity, which resulted in particles with significantly higher dimension size and weight (p&lt;0.05). A decrease in encapsulation efficiency was found at higher temperatures and lower pH values. However, higher encapsulation efficiency was observed in gel beads which contained whey protein (50A : 50W and 60A : 40W) at all conditions. An increased protein content resulted in a higher gel network density and retention of the α-mangostin in the beads. The released α-mangostin content decreased with increasing protein content at all conditions during storage. The results confirmed that the α-mangostin stability was significantly governed by both conditions and the use of whey protein to protect the target compound.</p> Tunyaporn Sirilert, Nattapol Kajonboon, Nattiga Silalai ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 The Effect of Inspiratory and Expiratory Muscle Warm-Up on Rowing Performance in Youth Rowers <p>Warm-up is an essential part of preparation for rowing, especially in competitions. Respiratory muscle warm-up has been proposed to be the beneficial warm-up protocol for enhancing rowing performance. Therefore, the aim of this study is to determine the effect of inspiratory and expiratory muscle warm-up on rowing performance. The design of the study is a crossover study with controlled experiments. Fourteen youth rowers from the Rower and Canoeing Association of Thailand (six males, eight females) had to perform two warm-up protocols: specific rowing warm-up (SWU) and a combination of inspiratory and expiratory muscle warm-up with specific rowing warm-up (RWU+SWU). Afterwards, they had to perform a six minute all-out test. Mean power, distance, pre- and post-maximum inspiratory and expiratory muscle strength (MIP, MEP) of these results were compared. The results showed no significant differences in mean power (p=0.233) and distance (p=0.177) between SWU and RWU+SWU. Furthermore, pre-post MIP and MEP were not different in both warm-up protocols. However, mean power and distance in male rowers tend to increase under the RWU+SWU protocol, but both of parameters result in females conversely. In conclusion, the effect of RWU+SWU on rowing performance is not different from SWU, but if gender is considered, male and female rowers will react to the RWU+SWU protocol differently. Hence, this should be further investigated with a larger number of participants.</p> Supattra Silapabanleng, Sasipa Buranapuntalug ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 Optimization and Validation Study of HPLC with Fluorescence Detection Method for Analysis of Benzo[C]Fluorine <p>Optimization and method validation of HPLC with fluorescence detector for the determination of benzo[c]fluorene were studied. The results showed that benzo[c]fluorene had a maximum excitation wavelength at 309 nm and a maximum emission wavelength at 354 nm. The mixture of acetonitrile-water was used as a mobile phase at a ratio of 85:15. The standard curve was linear over the concentration range of 0.5-50 ng/ml. The limit of detection and the limit of quantification were 0.27 ng/ml and 0.90 ng/ml, respectively. The relative standard deviation of precision for intra-day and inter- days were less than 5% for both low (5 ng/ml) and high (50 ng/ml) concentration of benzo[c]fluorene. The method was validated and showed satisfactory results of linearity, precision, limit of detection, and limit of quantification. Accuracy in terms of percent recovery strongly depends on sample matrix. Therefore, further studies are needed to investigate the accuracy when the method is applied in the real sample such as environmental and food samples.</p> Piyada Songsermsaku, Kazuichi Hayakawa ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 Design of Trajectory Tracking System for DC Motors with Uncertain Time-Varying Inertial Loads <p>We considered the problem in which a DC motor was controlled to track a given trajectory<br>when the corresponding driven load was associated with uncertain time-varying mass moment of<br>inertia. With the existence of such inertia variation, the corresponding system matrix and input<br>matrix of the control system were simultaneously uncertain and time-varying. Accordingly,<br>stability of the control system could not be guaranteed by simply locating all the poles of the<br>linearized model in the LHP at all time. Based on Lyapunov stability theorem, we came up with<br>a robust PID controller design technique that yielded satisfactory results for this problem. Our<br>robust PID controller was easy to implement, and guaranteed uniform input-to-state stability for<br>the system. It appeared in our investigation on a large Maxxon DC motor that our controller<br>allowed as high as 100% variation of equivalent inertia loading with respect to rotor inertia. We<br>provided a tool to facilitate controller tuning so that the resulting control signal stayed within<br>practical bounds, while achieving a satisfactory level of performance. By selecting an<br>appropriate transmission ratio, our tracking control system could be employed in demanding<br>applications such as independent joint control of robots, and spindle control of modern machining<br>machines.</p> Pinit Ngamsom ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 Sampled-data Modeling of a Single-Ended Primary Inductor Converter in Discontinuous Conduction Mode <p>This paper presents the small-signal modeling of a Single-Ended Primary Inductor<br>Converter power stage operating in discontinuous conduction mode using the sampled-data<br>modeling technique. In addition, two algebraic manipulating features are revealed; the simpler<br>periodic solution determination by the concept of Volt-Second and Capacitor-Charge balance,<br>and the replacement of the expression involving the singular matrix by the equivalent function<br>with the s  domain matrix. Four pulse transfer functions are derived from the model: the smallsignal<br>input-to-output voltage pulse transfer function, the small-signal duty duration-to-output<br>voltage pulse transfer function, the input-to-output voltage pulse transfer function, and the duty<br>duration-to-output voltage pulse transfer function. The model verification is analyzed by the<br>simulation results. The response sequences from the pulse transfer functions oscillate by the same<br>phase and frequency to the one from the simulation with slightly peak amplitude differences,<br>confirming the validity of the acquired pulse transfer functions.</p> Yossawee Weerakamhaeng ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700 Acceptor Specificity of Recombinant Cyclodextrin Glycosyltransferase from Bacillus circulans A11 <p>Cyclodextrin glycosyltransferase (CGTase) catalyzes an intermolecular transglycosylation reaction to produce functional oligosaccharides or glycosides, which can be used in several industries. In this study, the p19bBC recombinant cells containing CGTase gene from Bacillus circulans A11 were used for synthesizing CGTase. The maximum expression was obtained when the p19bBC cells were cultured at 37oC for 24 h with 0.2 mM IPTG. The recombinant CGTase was purified up to 6-fold by 5% (w/v) starch adsorption and the specific activity of enzyme was 1.08x104 units/mg with a 71% yield. The 72-kDa relative molecular mass of purified enzyme was determined by 10% SDS-PAGE. In addition, the acceptor specificity of enzyme was investigated from transglycosylation reaction using β-cyclodextrin as glycosyl donor and various saccharides and flavonoids as acceptors. Among the group of saccharide acceptors, glucose gave the highest activity, followed by maltose and mannose. Within the flavonoid group, hesperidin gave the highest activity with 13.5% as compared to glucose. Due to the broad range of bioactivities of hesperidin flavonoid, and also, the possibility of new glycoside products, this study suggested that using hesperidin as an acceptor is far superior to the saccharides in terms of further applications.</p> Titaporn Chaisin, Jarunee Kaulpiboon, Natwadee Poomipark ##submission.copyrightStatement## Sat, 30 Jun 2018 00:00:00 +0700