Rerkratn, Apinai

Preferred name

Rerkratn, Apinai

Alternative Name

Rerkratn, A.

Main Affiliation

School of Engineering

apinai.re@kmitl.ac.th

Now showing 1 - 10 of 10

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8-Electrode data collection system for electrical capacitance tomography
(2006-12-01)
Rerkratn, Apinai
;
Lertpakdee, Thanakorn
;
Chitsakul, Kitiphol
;
Sangworasil, Manas
;
Petchmaneelumka, Wandee
8-electrode data collection system for electrical capacitance tomography is presented. The system mainly consists of a signal generator, 8×2 multiplexer, detector, amplifier, band-pass filter, rms-to-dc converter, A/D converter circuit and control computer. Experimental results with a circular sensor show that the proposed system is able to collect data with satisfy sensitivities, linearity, resolution and also being insensitive to noise. Reconstructed images from collected data are shown. © 2006 ICASE.
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Electrical impedance tomography system using 3D finite element algorithm
(2000-12-01)
Rerkratn, A.
;
Chitsakul, K.
;
Suwanna, P.
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Sangworasil, M.
A 3D finite element model is used for solving the problem of nonlinearity and multidimensional distribution of electric field in the reconstruction of impedance tomographic image of a conductive object. The boundary values of the problem are the small current injected through the cross-section and voltage measured around the object. The Newton-Raphson method is used for varying the resistivity distribution to fit the set of the measured voltage. The calculated resistivity of each elements can be reconstructed the image of cross-section. The experimental results with saline tank phantom are shown the reduction of the error, comparing to 2D model, due to the position of electrodes around the object and distribution of electric field along the thickness of the object.
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Voltage signal Max/Min finder
(2009-12-01)
Lekthamrong, Chanon
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Rerkratn, Apinai
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Petchmaneelumka, Wandee
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Riewruja, Vanchai
In this paper, a circuit technique to realize Max/Min finder for fuzzy applications is presented. The maximum or minimum operation can be provided by setting the external control current without changing the topology, while the input signals are in the voltage forms. The proposed Max/Min finder configuration is simple and suitable for fabrication in standard CMOS technology. The circuit performance is studied using PSPICE analog simulation program. Simulation results verifying the performance of the proposed scheme are agreed with the expected values. © 2009 SICE.
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4-channel bio-impedance measurement system for medical applications
(2004-12-01)
Rerkratn, Apinai
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Chitsakul, Kitiphol
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Sangworasil, Manus
In this paper we introduce a new multi-channel system for measuring electrical impedance of biological tissues. This 4-channel impedance measurement system was designed to achieve high sensitivity, high resolution, good stability and safety for medical applications. The system consists of a sine-wave oscillator, an 16X4 multiplexer, a voltage control current source, an instrumentation amplifier, a band pass filter, a detector, a low pass filter, an isolation amplifier and an A/D converter. Results of some experiments with the resistance box have been shown that we have obtained a bio-impedance measurement system with high sensitivity, high resolution, good stability and safety for medical applications.
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Ultrasonic measuring circuit using sample and hold method
(2008-12-01)
Rerkratn, Apinai
;
Akejakrawan, Sakolkrit
;
Kaewpoonsuk, Anucha
This paper presents the simple ultrasonic measuring circuit using sample and hold method. The proposed method is to measure the transit time of ultrasonic wave in fluid. The system consists of the pulse generator circuit, amplifier circuits, band pass filter, detector circuit, comparator circuit, timing circuit, saw-tooth generator circuit, and sample and hold circuit. The voltage output signal of the proposed technique is proportional to the transit time. The sugar solution with differential concentrations was measured in our experiment as an illustrative case study. Experimental results show that the proposed method can measure the transition time of the ultrasonic signal with satisfied sensitivity and good linearity. © 2008 SICE.
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A novel resolver-to-DC converter based on OTA-based inverse-sine function circuit
(2008-12-01)
Kaewpoonsuk, Anucha
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Petchmaneelumka, Wandee
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Rerkratn, Apinai
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Tammaruckwattana, Sirichai
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Riewruja, Vanchai
A new technique for realizing the resolver-to-DC converter using the OTA-based inverse-sine function circuit is presented. The proposed converter comprises the demodulator, absolute detector, minimum detector, ± unity-gain amplifier, controlled signal logic circuit, and OTA-based inverse-sine function circuit. The output voltage is linearly proportional to the resolver angle with maximum absolute error of about 0.195%, which is less than the error from the conventional resolver-to-DC converter based on the similar OTA-based inverse-sine function circuit. PSPICE simulation and experimental results verifying the performances of the proposed circuit are in close agreement with the expected values. © 2008 SICE.
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Preparation and properties indium tin-oxide thin films by RF sputtered for photodetectors
(2008-01-01)
Srithanachai, I.
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Nutaman, K.
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Rerkratn, A.
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Niemcharoen, S.
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Supadech, S.
This paper descript studying and preparation indium-tin oxide (ITO) thin film from method 90 wt.% ln<inf>2</inf>O<inf>3</inf> and 10 wt.% SnO<inf>2</inf> formula target with 99.99% purity on glass slide by RF reactive sputtering method at room temperature. This paper, sputtering time 5, 15, 30 and 60 mins. Thin films ITO were measured crystallization, optical and electrical characteristic by an X-ray diffractometer (XRD), scan electron microscopy (SEM) , Four Point Probe and UV-VIS spectrophotometry. The results found that thin films which made from RF sputtering method had a high crystallization, order arrangement grain. Strong peak of XRD (400) and (441), low resistivity are 2.2 × 10-3 4.4 × 10-3 1 × 10-3 and 7 × 10-4 β-cm, transmittance are 82%, 84%, 87% and 89%, respectively. The overall experimental results identify that fabricated thin films ITO have good properties and is suitable for transparent electrode application. The ultimate goal is developing schottky photodetector. © 2008 Trans Tech Publications, Switzerland.
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An accurate CCII-based voltage controlled current source
(2008-12-01)
Kaewpoonsuk, Anucha
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Riewruja, Vancliai
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Rerkratn, Apinai
;
Kamsri, Thawatchai
In this paper, a voltage controlled current source (VCCS) providing low distortion in output signal and wide output current range is introducted. In order to obtain the high accuracy, the proposed technique employs the designed scheme to connect in feedback loop of the basic VCCS based on second generation current conveyor (CCII). This scheme consists of instrumentation and differential amplifiers and one resistor. The performances of the proposed circuit were studied through the use of PSPICE simulation program. Simulation results are agreed with the expected values.
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High current low frequency eddy current imaging system
(2007-12-01)
Rerkratn, Apinai
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Pulkham, Jirayut
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Chitsakul, Kitiphol
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Sangworasil, Manas
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Keawpoonsuk, Anucha
Eddy current technique plays an important role in non destructive test. Based on the principal of electromagnetism. We introduce, in this paper our new eddy current imaging system for flaw detection in aluminium plate. The propose system using high current and low frequency with single coil. Results of some preliminary experiments have been shown satisfy sensitivities, resolution and stability of the proposed system. © ICROS.
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Electrical capacitance tomography system for industrial applications
(2006-12-01)
Rerkratn, Apinai
;
Yossontiku, Chanrit
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Lertpakdee, Thanakorn
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Chitsakul, Kitiphol
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Sangworasil, Manas
An electrical capacitance tomography system (ECT) has been developed. The system consists of a circular sensor with 8 electrodes. A charge generator injects charges into the sensor filled with objects different dielectric constants. The charges, in the form of potential dropped, on another electrode are measured and acquired digitally to a PC for calculating the capacitance and estimating the dielectric distribution. Linear back-projection algorithm (LBP) with iterations is applied for reconstructing cross sectional images of the sensor. Some experiments as the sensor filled with vegetable oil and a Teflon bar placed on a specified area was carried on. We have found that the minimum and maximum capacitance between the electrode pairs is about 0.1245 pF and 2.6760 pF respectively. These very low capacitance values suggested that the measuring circuit being implemented should have high sensitivity and also be insensitive to noise. The reconstructed images of the object closely resemble the cross-section of the specific test phantom. The low gray level artifacts, however often present in the reconstructed image because of the limitation of the LBP algorithm. This may be improved by using image thresholding or using suitable number of iterations.

Rerkratn, Apinai

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