Isarakorn, Don

Preferred name

Isarakorn, Don

Alternative Name

Isarakorn, D.

Main Affiliation

School of Engineering

don.is@kmitl.ac.th

Now showing 1 - 10 of 26

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Automatic exudate extraction for early detection of Diabetic Retinopathy
(2013-01-01)
Sreng, Syna
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Takada, Jun Ichi
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Maneerat, Noppadol
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Isarakorn, Don
;
Pasaya, Bundit
Diabetic Retinopathy (DR) is the most common cause of blindness in diabetic patients, but early detection and timely treatment can prevent this problem. Exudates have been found to be one of the signs and serious DR anomalies so the proper detection of these lesions and the treatment should be done immediately to prevent loss of vision. The aim of this study is to automatically detect these lesions in fundus images. To achieve this goal, the proposed method first preprocesses to improve the quality of fundus image, and then Optic Disc (OD) is detected and eliminated to prevent the interference to the result of exudate detection by combination of 3 methods; image binarization, Region Of Interest (ROI) based segmentation and Morphological Reconstruction (MR). Next, exudates are detected by applying the maximum entropy thresholding to filter out the bright pixels from the result of OD region eliminated. Since the result contains some noises which appear as bright light at the edge of fundus area in some images, that affect is considered and eliminated to improve the result of false positive. Finally, exudates are extracted by using MR. The proposed technique has been tested on 100 fundus images from hospital. Experimental results show that 91 % of exudate is extracted correctly with the average process of 3.92 second per image. © 2013 IEEE.
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Comparative study of QCM analyzers based on pierce oscillator and electromechanical impedance techniques
(2017-02-21)
Jayasvasti, Subhawat
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Isarakorn, Don
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Nundrakwang, Songmoung
This paper presents a comparison between pierce oscillator and impedance analysis techniques for measuring the frequency of the quartz crystal. The QCM analyzer based on pierce oscillator is designed, realized, and then compared to the impedance analyzer (Type bode 100). The comparison is focused on accuracy and precision of measurement. The pierce oscillator in a completed-chip is employed in the QCM analyzing device in order to simplify the circuit of system. The frequency drift and standard deviation (SD) values which are obtained from resonant frequency measurement are studied in order to investigate the accurate and precise measurement of devices. In the experiment, an AT-cut quartz disc of crystal oscillator package HC49U is unloaded and loaded while it is being measured the frequency. From the experimental results, the QCM analyzer based on pierce oscillator and impedance analyzer have the approximate accuracy and precision of measurement. The QCM analyzer based on pierce oscillator has lower sensitivity due to the frequency drift.
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Polymer based microneedle patch fabricated using microinjection moulding
(2018-08-14)
Janphuang, Pattanaphong
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Laebua, Mongkhol
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Sriphung, Chanwut
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Taweewat, Phatsakon
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Sirichalarmkul, Anan
This paper presents the development of a polymer based microneedle patch for transdermal drug delivery application using plastic microinjection moulding. Design and analysis of the microneedle cavities and mould insert used in the injection moulding process were carried out using Computer-Aided Engineering (CAE) software. A mould insert with low surface roughness was fabricated using Micro Electrical Discharge Machining (μ-EDM). The injection moulding parameters including clamping force, temperature, injection pressure and velocity were characterized in order to obtain the optimum reproducibility. Solid truncated cone microneedles, made of biocompatible polymethyl methacrylate (PMMA), with a round tip radius of 50 μm and 500 μm in height have been realized by microinjection moulding process demonstrating the potential of a low cost, high production efficiency, and suitable for mass production. In addition, a mould insert of cylindrical microneedles fabricated using X-ray LIGA has been proposed.
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Electrical and dielectric properties of barium titanate–polydimethylsiloxane nanocomposite with 0-3 connectivity modified with carbon nanotube (CNT)
(2019-01-02)
Nawanil, Chanisa
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Makcharoen, Worawut
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Khaosa-Ard, Krittanat
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Maluangnont, Tosapol
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Vittayakorn, Wanwilai
This study explored the preparation and electrical properties of 0–3 barium titanate/polydimethylsiloxane nanocomposites by dispersing barium titanate nanoparticles (BaTiO<inf>3</inf>; BT) into the polydimethylsiloxane (PDMS) matrix phase. The effect of barium titanate nanoparticles on electrical properties has been investigated systematically, and the relative permittivity of nanocomposites was found to increase significantly with increasing barium titanate content. Different theoretical models were used to predict the dielectric constant of these composites and compare their experimental value with the theoretical value in order to find an appropriate equation. The result indicated that the dielectric properties of composites are influenced not only by relative permittivity of the components but also dependence on interactions between ceramics and polymers. Furthermore, the preparation and dielectric properties of BT/PDMS nanocomposites modified with carbon nanotube (CNT) were also studied. The dielectric results demonstrate that adding CNT can enhance the relative permittivity of the BT/PDMS composite via improvement of dispersion and distribution of the BT nanoparticles in the PDMS matrix phase. Moreover, the electrical outputs from the BT/PDMS/CNT nanocomposites generator were measured under periodic knocking. The nanocomposites innovatively expand the feasibility of self-powered energy systems for smart sensor and energy harvesting applications.
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Design and realization of an energy autonomous wireless sensor system for ball screw fault diagnosis
(2017-05-01)
Sudhawiyangkul, Thapanun
;
Isarakorn, Don
This paper presents the design and realization of an energy autonomous wireless sensor system for monitoring and fault diagnosis of ball screw condition. The proposed system is mainly composed of a wireless sensor node and an energy harvester. The novelty of the proposed system is lying in the point that it can be used with any machines that have a linear actuator and generate a low level of vibrations. The sensor node is used to measure the vibration of the ball screw in a linear actuator, while the energy harvester is used to convert linear kinetic motions of the actuator to electrical energy and powered the system. In this work, the design of wireless sensor node, energy harvester and energy management system are proposed. The electrical characteristics of the sensor node and the harvester are investigated to optimize the performance of the system. Lastly, sixteen energy autonomous wireless sensor nodes are fabricated and installed into the DISCO Automatic Dicing Saw DFD6340 machines for examining their performances. As the results, the proposed system can distinguish the condition of ball screw. The average acceleration level of ball screw showing some damage is significantly higher than the average acceleration level of ball screw with normal condition.
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Fabrication and evaluation of energy harvesting floor using piezoelectric frequency up-converting mechanism
(2018-08-15)
Panthongsy, Phosy
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Isarakorn, Don
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Janphuang, Pattanaphong
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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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Comparative study of piezoelectric energy harvesters based on polycrystalline PZT and single-crystalline PMN-PT materials
(2016-09-06)
Panthongsy, Phosy
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Isarakorn, Don
The piezoelectric energy harvester for supplying power to low-power electronic devices, especially low-power wireless sensor node has been studied and received more attraction over the past decade. In order to simplify installation and obtain the sufficient power for systems, the harvester possessing simple structure with highest output power is highly required. The aim of this study is to design and compare the characteristic and performance of piezoelectric polycrystalline PZT and single-crystalline PMN-PT energy harvesters based on unimorph configuration. By utilizing ANSYS<sup>®</sup> for finite element analysis (FEA), the numerical model of composite piezoelectric unimorph generators with proof mass exciting at resonant frequency 150 Hz are designed and then fabricated. For the energy harvesting experiment, the prototypes of harvesters are mounted to the electromagnetic shaker and inputted the vibration with vary frequencies and accelerations. As the results, the piezoelectric single-crystalline PMN-PT unimorph energy harvester has the higher energy density which is 352.85 J/gm<sup>3</sup>, while the piezoelectric polycrystalline PZT unimorph energy harvester has 8.44 J/gm<inf>3</inf>.
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Indoor positioning system on identification of neurodegenerative disease: A comparative study of BLE versus RFID
(2019-07-01)
Jayasvasti, Subhawat
;
Isarakorn, Don
This paper introduces the feasibility examination of indoor positioning system using the Bluetooth low energy (BLE) and the radio-frequency identification (RFID) devices to further apply in the diagnosis of neurodegenerative disease leading an unusual human body motion. Experimentally, a BLE module and a RFID tag are simulated to be the wearable devices mounted to human body, moving with common body motions. Their movements affecting on position tracking efficiency are investigated through smartphone and ultra-high frequency RFID reader, respectively. The results show that a BLE device presents the best position sensing ability.
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Piezoelectric energy harvesting from machine vibrations for wireless sensor system
(2015-08-17)
Panthongsy, Phosy
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Isarakorn, Don
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Sudhawiyangkul, Thapanun
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Nundrakwang, Songmoung
In recent years, wireless sensor network is used in a variety of applications and highly required. These wireless sensor network is powered by the battery with limit energy. Therefore, the integration of energy harvester and wireless sensor network has received more attention because it can prolong the lifetime of battery in a sensor node. The focus of this paper is to design the energy harvesting device from machine vibrations for wireless sensor node, which the amplitude and frequency of vibration source were contributed on the design. The structure of energy harvesting devices is a resonant type piezoelectric energy harvester with a proof mass at the tip of the beam for tuning its resonant frequency. The proposed piezoelectric energy harvesters were then designed and analyzed by using Finite Element Method (FEM) to optimize the natural frequency of the harvester. Then, the prototype energy harvesters were made and mounted to a vibration source for experiments. The result reveals that the optimal piezoelectric energy harvester can generate the output power of 82.29 μW at the resonant frequency of 50 Hz.
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DC motor control using CDM based two-degree-of-freedom controller for desired tracking and disturbance rejection characteristics
(2012-12-01)
Isarakorn, Don
This paper focuses on a design of two-degree-of-freedom (2DOF) controller by Coefficient Diagram Method (CDM) for position control of a DC motor. It is known that the 2DOF control system can be designed to meet both tracking and disturbance rejection performances, which are the most important for the position control system. Nevertheless, it requires tuning of many parameters. The CDM is an efficient method in designing the parameters of 2DOF controller based on the stability and the speed of the controlled system so that the desired performance criteria can be met. By the proposed design method, the parameters of 2DOF controller for a DC motor control system are obtained properly without any adjustment. Furthermore, the tracking and disturbance rejection performances are simultaneously designed. The results reveal the versatility of the CDM tuning technique in the position control of a DC motor. © 2012 ICROS.

Isarakorn, Don

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