Nunak, Navaphattra
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Nunak, Navaphattra
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Nunak, N.
Nunak, Navapattra
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navaphattra.nu@kmitl.ac.th
30 results
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Item type:Publication, Effect of Installation Angle of Ultrasonic Flow Meter on Water Velocity Measurement in Pipe(2017-01-01); The aim of this paper was to study the effect of installation angle of ultrasonic flow meter on the water velocity measurement in a pipe. The path angles of 45º, 55º, 65º, 75º, and 85ºwere performed in this study. The velocities were estimated by CFD techniques using the realizable k-ε model and measured by a transit time ultrasonic flow meter, and then they are compared with the results obtained from weighing method (ISO 4185). It was found that velocities estimated from CFD flow simulation at various path angles and measured from ultrasonic flow meter had a similar trend. The more difference of path angle away from the recommended specification was set, the more error of velocity measurement was obtained. The velocities at the path angles of 65ºand 85ºwere almost the same because they had an equal difference of path angle from the one that suggested in the specification. The simulated results from CFD had much error than the measured velocities of ultrasonic flow meter, especially at the long distance of path length or at a small path angle. This needed to be compensated with the correction factor. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Optimal Design and Installation of Solar Rooftop for Thai government building(2025-01-01); ; This research presents an approach for installing grid-connected solar cells on the rooftops of a prototype building in Thailand to offset electricity consumption, aligning with TOU electricity pricing. It includes design methods, energy-saving calculations, and illustrates the savings from solar cell installation over a one-year period, without accounting for solar cell deterioration or system loss charges. The study compares the concept of installing solar cells on the rooftop based on the building's electricity usage characteristics, distinguishing between installing solar cells across the entire rooftop area and according to the building's electricity usage behavior during daytime and working days, ensuring minimal electricity remains while still being sufficient for use. Furthermore, it calculates the comparison before and after installation to provide information for rooftop installation on the prototype building. The research results indicate that installing solar cells across the entire rooftop area can save electricity costs up to 550,000 THB per year. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Similarity model for estimating the error of clamp-on ultrasonic flowmeter: Flow in water supply piping system(2017-01-01); ; This study was aimed at presenting the similarity model for the estimation of error of a clamp-on, transit-time ultrasonic flow measurement. Dimensional analysis was based on the Buckingham Pi’s theorem. The groups of independent parameters that were taken into account for the analysis included pipe characteristic, fluid characteristic, and meter installation setting. Experimental testing section was fabricated using PVC pipes with diameters of 1-in and 2-in and 45º PVC elbows. Flow velocity was fixed at 0.5 m/s. The upstream and downstream distances were in the ranges of 2D-20D and 2D-10D, respectively. It was found that the upstream and downstream distances greatly affected the accuracy of the measurement. Larger relative errors were found from the measurement on the smaller pipe. With the installation of ultrasonic transducers according to the recommended value by FCI, the error obtained with the measurements on 1-in and 2-in diameter pipes were, respectively, 7% and 0.35%. The acceptable measurement ranges of upstream distance for 1-in and 2-in diameter pipes were 16D-20D and 6D-20D, respectively. The measurements on a 2-in diameter pipe with a downstream distance in a range of 4D-10D was acceptable. For the 1-in diameter pipe, any downstream distance less than 10D resulted in unacceptable error. The accuracy of measurement was more sensitive to the change of downstream distance than the change of upstream distance. The applicable range of the prototype prediction equation was greatly affected by the flow model. The equation obtained with a 1-in diameter flow model could only be used to predict a 2-in diameter prototype within a range of 18D-20D. Increasing the size a flow model could greatly broaden the applicable range the applicable range of the prediction equation. A 2-in diameter flow model could be used to predict a prototype upto 150 in. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Estimating the Power Losses in Induction Motor using Temperature Monitoring(2025-01-01); ; The paper proposes the estimation of power losses in electrical machines using a measurement technique based on the temperature of the electrical machine and the heat transfer equation. To demonstrate this concept, the heat diffusivity of the induction motor can be illustrated through thermal images. This research addresses the impact of supply voltage unbalance on power loss in induction motors. The system comprises A contact temperature measuring circuit utilizing the IC LM 35DZ as a temperature sensor and signal converter, paired with a computer equipped with a National Instruments PCI 6014 data acquisition card. The experiment was conducted by adjusting the phase unbalance to 10%, 20%, and 50% to observe temperature changes. This allows for a direct temperature in the induction motor. The primary advantage of this method is that the machines do not need to stop or be removed from their operational process to measure their losses during preliminary maintenance. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An investigation of oil residue on surface by infrared thermography(2020-01-01); ; This work aims to propose a visual inspection, infrared thermography technique, of oil residual mass on stainless steel surface (SS) (hydrophilic surface representative) and polytetrafluoroethylene (PTFE) surface (hydrophobic surface representative). An improved understanding of the oil fouling characteristic is a key point to develop this technique. The effect of surface roughness on the oil contact angle, oil residual mass, and the resulting average temperature of the residues on SS and PTFE surface was studied. For the infrared thermography technique, the mass of oil adhered to each interface using heating at a temperature of 80<sup>0</sup>C for 10 minutes. SS AISI 304 plaques with the average surface roughness of 0.4, 0.8, and 3.2 µm and PTFE with that of 0.4 and 0.8 µm were examined. All samples were snapped top view using a thermal image camera. The average temperatures were obtained from the color spectrum of the thermal images. It could be summarized that the proposed measurement is possible to detect the accumulation of oil on the SS whereas it was not clearly different that on the PTFE surface. A greater oil residual mass on both hydrophilic and hydrophobic surfaces is a result of an increase in surface roughness and sequential wettability from the contact angle as expected. Moreover, each liquid-solid interfacial material has its specific surface characteristic. Finally, each liquid-solid interfacial material has its specific surface characteristic and the new and used oil-SS interface could be detected by infrared thermography technique. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, 3D inspection for HDD production process using laser light sectioning(2015-01-01); This research proposes the automatic visual inspection from three-dimensional characteristics of Hard Disk Drive case tightening process by machine vision system using laser light sectioning. The machine vision camera captures a number of features of HDD perpendicular to a conveyor belt as seen by a laser strip light. The narrow band pass filter (650 nm.) was mouthed in front of lens in order to cut off the unwanted wavelength. After image pre-processing, the laser profiles were calculated the center of gravity to extract the image coordinate. The features used here are the laser strip profile at various locations along the HDD formulating the 3D data. The homography computation was used to transform the image coordinate to the real world distance (in metric system). This scheme can be used to inspect the completeness of screwing process of the HDD which the 2D visual inspection cannot perform on the top view. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal image resolution on angular emissivity measurements using infrared thermography(2015-01-01); This paper reports the effect of viewing angle and thermal image resolution (IFOV and FOV) of Thermal Imager (TI) on the emissivity, with a view to providing a potential temperature monitoring of equipment in the electrical power distribution system which the reliability of system is the most important concern. The results show that the emissivity, which is the most important parameter to obtain the accurate temperature, is approximately constant at the viewing angle less than 45°. In case of the changing of the object to detector distance, this will not affect to the temperature measurement if MFOV at the object level is smaller than the targeted object. This can be concluded that TI is an effective tool to measure the temperature and monitor the failure of electrical equipment installed in the position at far away from the operator. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Similarity Model of MWA Thailand Water System for Error Estimation of Ultrasonic Flow Meter(2017-01-01); This paper proposed a similarity model of MWA water system using the dimensional analysis based on the theory of Buckingham Pi for error estimation of transit-time ultrasonic flow meter with clamp-on at different installation conditions. There were three main parameters groups, i.e., pipe characteristic, meter installation, and fluid characteristic and properties and could be arranged in five Pi terms, i.e. E×(L<inf>e</inf>/D), µ/ρvD, L<inf>e</inf>/D, U<inf>s</inf>/D and U<inf>s</inf>/D. The results showed that the relative errors of measurement increased with the decreasing of upstream and downstream of meter at the same velocity and there was a possibility to use the model to determine the correction factor to compensate the velocity measurement of ultrasonic flow meter as the installation could not comply with the requirement. However, the further experiments should be performed for validation of the model predictive equation i.e., E 0.3607 E <sup>.</sup> p m. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Detection of Foreign Bodies in Roasted Coffee by using Active Thermography(2017-01-01); This paper presents the detection of foreign bodies in roasted coffee by using active thermography with real-time thermal image processing. Foreign bodies, including stone, wood, etc., are found in roasted coffee beans contaminated during drying process and transportation. The principle of radiation from objects with different emissivity and heat capacity is applied. The heat radiation from the roasted coffee and the foreign body are different; therefore, the thermal image can be used to identify the foreign objects. The active thermography system consists of a thermal image camera and computer image processing, heat source and conveyor system controlled by programmable logic controller. The testing and experimental results of the proposed system show that the foreign bodies in roasted coffee beans can be found in all batches, however, the number counting of foreign objects are inaccurate. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, DEVELOPMENT OF OBJECT DETECTION AND CLASSIFICATION WITH YOLOV4 FOR SIMILAR AND STRUCTURAL DEFORMED FISH(2022-03-31); ; Food scarcity is an issue of concern due to the continued growth of the human population and the threat of global warming and climate change. Increasing food production is expected to meet the challenges of food needs that will continue to increase in the future. Automation is one of the solutions to increase food productivity, including in the aquaculture industry, where fish recognition is essential to support it. This paper presents fish recognition using YOLO version 4 (YOLOv4) on the «Fish-Pak» dataset, which contains six species of identical and structurally damaged fish, both of which are characteristics of fish processed in the aquaculture industry. Data augmentation was generated to meet the validation criteria and improve the data balance between classes. For fish images on a conveyor, flip, rotation, and translation augmentation techniques are appropriate. YOLOv4 was applied to the whole fish body and then combined with several techniques to determine the impact on the accuracy of the results. These techniques include landmarking, subclassing, adding scale data, adding head data, and class elimination. Performance for each model was evaluated with a confusion matrix, and analysis of the impact of the combination of these techniques was also reviewed. From the experimental test results, the accuracy of YOLOv4 for the whole fish body is only 43.01 %. The result rose to 72.65 % with the landmarking technique, then rose to 76.64 % with the subclassing technique, and finally rose to 77.42 % by adding scale data. The accuracy did not improve to 76.47 % by adding head data, and the accuracy rose to 98.75 % with the class elimination technique. The final result was excellent and acceptable.