Isarakorn, Don

Preferred name

Isarakorn, Don

Alternative Name

Isarakorn, D.

Main Affiliation

School of Engineering

don.is@kmitl.ac.th

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Fabrication and evaluation of energy harvesting floor using piezoelectric frequency up-converting mechanism
(2018-08-15)
Panthongsy, Phosy
;
Isarakorn, Don
;
Janphuang, Pattanaphong
;
Hamamoto, Kazuhiko
This paper reports on the fabrication and evaluation of an energy harvesting floor tile using unimorph PZT piezoelectric cantilevers to convert kinetic energy from human footsteps into usable electricity. The operation of the tile is based on frequency up-converting mechanism in which low frequency input vibrations are converted into high frequency vibrations of an electromechanical transduction. The operational frequency of the PZT unimorph cantilever was converted up by an interaction between a permanent magnet and an iron bar. Vertical displacement of the oscillating cantilever was localized with a stopper preventing damage to the piezoelectric layer from shock or over-displacement excitation. The magnetic field density between the magnet and the iron bar was investigated through finite element analysis simulation in order to define an optimal air gap. Experimentally, a unimorph PZT cantilever was initially prototyped to validate the design. The results showed a successful frequency up-conversion with a resonant frequency of 10.54 Hz. Then, it was scaled up by accommodating 24 unimorph PZT cantilevers followed by experimental validation to evaluate its energy harvesting performance. Each cantilever was connected to a full wave bridge rectifier then connected in parallel with the other cantilevers. The generated electrical power and energy were investigated through various resistive loads. The average power and total output energy produced by one foot step on the tile were found to be 1.24 mW and 3.49 mJ, respectively at an optimal load resistance of 74.44 kΩ. The energy conversion efficiency reached 17.12% demonstrating the potential of harvesting energy from human motion.
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Primary screening of diabetic retinopathy based on integrating morphological operation and support vector machine
(2017-07-02)
Sreng, Syna
;
Maneerat, Noppadol
;
Isarakorn, Don
;
Hamamoto, Kazuhiko
;
Panjaphongse, Ronakorn
Diabetic retinopathy is one of the most frequent causes of blindness due to diabetes. Primary screening is essential due to prerequisite step toward the diagnosis of diabetic retinopathy in order to prevent vision loss or blindness. This paper presents the methods to discriminate between healthy images and diabetic retinopathy images on the retinal images. The proposed method involves three main steps. Initially, the image is preprocessed to remove small noises and enhance the contrast of the image. Secondly, Kirsch edge detection is utilized to detect the bright lesions. Subsequently, the red lesions are detected depending on top-hat morphological filtering methods. Then the bright and dark lesions are combined by using logical AND operator. In order to be left only pathological signs, the noises near the vicinity of the optic disc and blood vessels are further removed using blob analysis. Finally, morphological features are extracted and fed to the SVM classifier. The proposed method was evaluated with three datasets containing 229 images. It achieved the accuracy of 90%, sensitivity of 86.33% and specificity of 98.55% with the average computational time 8 seconds per image. The method is simple and fast, easy to implement and the result is promising.
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Design and evaluation of double-stage energy harvesting floor tile
(2019-10-01)
Isarakorn, Don
;
Jayasvasti, Subhawat
;
Panthongsy, Phosy
;
Janphuang, Pattanaphong
;
Hamamoto, Kazuhiko
This paper introduces the design and characterization of a double-stage energy harvesting floor tile that uses a piezoelectric cantilever to generate electricity from human footsteps. A frequency up-conversion principle, in the form of an overshooting piezoelectric cantilever, plucked with a proof mass is utilized to increase energy conversion efficiency. The overshoot of the proof mass is implemented by a mechanical impact between a moving cover plate and a stopper to prevent damage to the plucked piezoelectric element. In an experiment, the piezoelectric cantilever of a floor tile prototype was excited by a pneumatic actuator that simulated human footsteps. The key parameters affecting the electrical power and energy outputs were investigated by actuating the prototype with a few kinds of excitation input. It was found that, when actuated by a single simulated footstep, the prototype was able to produce electrical power and energy in two stages. The cantilever resonated at a frequency of 14.08 Hz. The output electricity was directly proportional to the acceleration of the moving cover plate and the gap between the cover plate and the stopper. An average power of 0.82 mW and a total energy of 2.40 mJ were obtained at an acceleration of 0.93 g and a gap of 4 mm. The prototype had a simple structure and was able to operate over a wide range of frequencies.
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A test bench for characterization of piezoelectric frequency up-converting energy harvesters
(2018-07-02)
Panthongsy, Phosy
;
Isarakorn, Don
;
Hamamoto, Kazuhiko
This work focuses on the design and realization of a test bench used to characterize the performances of the piezoelectric cantilever for frequency up-converting energy harvesters. A test bench is completed by combining a frequency up-converter with an oscilloscope (Tektronix TD 3032B). The frequency up-conversion mechanism achieves the excitation on a piezoelectric cantilever through an interaction between a permanent magnet and an iron bar. In the mechanism design, the air gap between a permanent magnet and an iron bar is analyzed by Finite Element Method (FEM). After the design is verified, a test bench is fabricated and then validated with experimental study by testing the performances of a PZT-5H bimorph (T220-H4-503X, Piezo Systems, Inc.); the considered performances are resonant frequency, average output power, total output energy and energy conversion efficiency. The experimental results demonstrate that a fabricated test bench is satisfactory.
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Automatic hemorrhages detection based on fundus images
(2015-01-01)
Sreng, Syna
;
Maneerat, Noppadol
;
Isarakorn, Don
;
Hamamoto, Kazuhiko
;
Panjaphongse, Ronakorn
This paper proposes methods to detect hemorrhages which are known as a kind of lesions in diabetic retinopathy. To detect the symptom, eye fundus structures (blood vessels and fovea) as well as microaneuysms need to be discriminated to filter out only the hemorrhages. Five processing steps are proposed based analysis on fundus images. First, preprocessing step is processed to improve the quality of the image. Then all red features are filtered out. They include blood vessels, fovea, microaneurysms and hemorrhages. After that, morphology operation and compactness measurement are applied to eliminate the fovea, and blood vessels. Finally, hemorrhages can be classified by using area method to remove microaneurysms and some small noise. 579 fundus images from Bhumibol Adulyadej Hospital were tested. The results were analysis by ophthalmologist in order to define system accuracy and preciseness. According to results of comparison, we found that the accuracy is 90 % and the average of processing time is 6.23 seconds per image.
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Performance and behavior analysis of piezoelectric energy harvesting floor tiles
(2019-07-01)
Panthongsy, Phosy
;
Isarakorn, Don
;
Hamamoto, Kazuhiko
;
Janphuang, Pattanaphong
This paper presents the performance and behavior analysis of two unlike piezoelectric energy harvesting floor tiles in which they are functioned with different frequency up-conversion strategies to achieve the high energy conversion efficiency from low and variable-frequency vibration as the human footstep. One of such strategies is to convert the frequency of piezoelectric bimorph up through the magnetic interaction between a permanent magnet and an iron plate, while another one is achieved on that through the mechanical impact between a cover plate and a wall of the floor tile. Experimentally, the floor tiles having one piezoelectric bimorph inside of them are prototyped and then mounted to their individual input-exciting kit to investigate the energy harvesting performance. The input-exciting kits are employed to simulate the human footstep on floor tiles. The results show that the floor tile with frequency up-converting mechanism based on mechanical impact should be a better option for energy harvesting from human footstep due to the low-profile structure and good energy harvesting performance. Moreover, its operational way can result in long-lasting piezoelectric bimorph. When a cover plate is actuated to move down with the velocity of 54.13 mm/s and then released, the floor tile can produce the average power of 0.82 mW at load resistance approximately of 55.68 kΩ.

Isarakorn, Don

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