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    Item type:Publication,
    DETECTION OF DRIVER DROWSINESS FROM EEG SIGNALS USING WEARABLE BRAIN SENSING HEADBAND
    (2021-05-31)
    Chan, Khune Satt Nyein
    ;
    Srisurangkul, C.
    ;
    Depaiwa, N.
    ;
    Pangkreung, S.
    Driver drowsiness detection plays an important role in the field of road safety and advanced driver assistance system. Electroencephalogram (EEG) signals are one of the most accurate and reliable indicators of fatigue and drowsiness but in the case of detecting drowsiness, its medical graded measuring system can be intrusive to the driver. The purpose of this research is to test the feasibility and usability of the consumer graded EEG sensor to use in a driver drowsiness detection system. The experiment was carried out by using MUSE S brain sensing headband. Fast Fourier Transform (FFT) method was used to extract features from EEG signals. The extracted feature data are then used to build two classification model, the Support Vector Machine (SVM) and Artificial Neural Network (ANN). The detection of drowsiness is the binary classification task which is to classify between drowsy epochs and alert epochs. In the case of detecting only drowsy epochs, the SVM model detected 82.7% of the drowsy epochs which was better than the ANN model which can only detect 81.25% of the drowsy epochs. But in the detection of both drowsy and alert epochs, the ANN model performed better than that of SVM. The SVM model was tested with different kernel function and Fine Gaussian SVM model showed the highest accuracy of 87.8%. The ANN model performed slightly higher than the SVM model with an accuracy of 87.9%. The ability of consumer graded EEG sensor to use in drowsiness detection system was validated in this research.
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    Item type:Publication,
    IMPROVEMENT OF ESTIMATION METHOD FOR BATTERY CELL HEAT GENERATION
    (2021-05-31)
    Kulranut, J.
    ;
    Depaiwa, N.
    ;
    Yenwichai, T.
    ;
    Intano, W.
    ;
    Masomtob, M.
    This work represents a new experimental method to precisely estimate the heat generation of the battery cell by reducing heat losses to the ambient. The temperature ambient in the chamber is controlled to be close to the battery cell temperature as much as possible in order to reduce the heat loss from the battery to the ambient. The battery is covered by an insulator, and the heat loss due to the heat conduction at the electric connectors is also considered. Therefore, the heat generation term is absorbed by the heat capacity term; in other words, the heat generation of the battery cell can be calculated via the rising temperature of the heat capacity term and the heat loss of the connectors. Consequently, this new method can obtain the precision of the estimated heat generation that can be used to design an appropriate battery thermal management system for the battery pack.
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    Item type:Publication,
    Flow stress determination of steel tube for hydroformability evaluation
    (2013-08-01)
    Boonpuek, P.
    ;
    Jirathearanat, S.
    ;
    Depaiwa, N.
    This study aims to determine flow stress of a steel tube by using hydraulic bulge test. A new proposed analytical model for analyzing bulge shapes of hydroformed tubes is postulated. Bulge test apparatus designed using FEA simulation of hydroforming and STKM 11A steel tubes are used in the hydraulic bulge test. Bulge heights and internal pressures are measured during bulge testing. Tube thicknesses at vertex of a bulge shape are measured by a dial caliper gauge. Bulge curvatures and contact points are measured by taking digital photos of bulge shapes combined with measurement methods in CAD software. Effective stress-strain relationships are obtained from the newly developed analytical model using those measured values. Flow stress curves obtained from the effective stress-strain relationships are compared with those by other researchers and tensile test. Finite element analysis methods are used to conduct simulation of tube hydroforming using the flow stress curves. Predicted internal pressures versus bulge heights and tube thicknesses are compared with experimental results. Verification of the developed analytical model is presented. The flow stress at neck point of the formed tube is determined. © 2013 American Scientific Publishers All rights reserved.
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    Item type:Publication,
    Flow stress determination of steel tube for hydroformability evaluation
    (2013-01-28)
    Boonpuek, P.
    ;
    Jirathearanat, S.
    ;
    Depaiwa, N.
    This study aims to determine flow stress of a steel tube by using hydraulic bulge test. A new proposed analytical model for analyzing bulge shapes of hydroformed tubes is postulated. Bulge test apparatus designed using FEA simulation of hydroforming and STKM 11A steel tubes are used in the hydraulic bulge test. Bulge heights and internal pressures are measured during bulge testing. Tube thicknesses at vertex of a bulge shape are measured by a dial caliper gauge. Bulge curvatures and contact points are measured by taking digital photos of bulge shapes combined with measurement methods in CAD software. Effective stress - strain relationships are obtained from the newly developed analytical model using those measured values. Flow stress curves obtained from the effective stress - strain relationships are compared with those by other researchers and tensile test. Finite element analysis methods are used to conduct simulation of tube hydroforming using the flow stress curves. Predicted internal pressures versus bulge heights and tube thicknesses are compared with experimental results. Verification of the developed analytical model is presented. The flow stress at neck point of formed tube is determined. © (2013) Trans Tech Publications, Switzerland.