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Modified beat segmentation for DTW based ECG compression
(2015-01-26)
Chompusri, Yotaka
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Dejhan, Kobchai
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Yimman, Surapun
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Charbkaew, Noppadol
The proposed ECG compression method presents the new beat segmentation algorithm. Because this proposed compression method uses the residual difference between original ECG signal beat and the reference ECG beat, the ECG signal must be separated into each beat before doing the compression process. That is the duty of beat segmentation process. Therefore, this process is important step of the selective Mapping Technique ECG compression method. The main goal of this work is to design the beat segmentation algorithm which is the most suitable for this compression method. And this proposed beat segmentation algorithm is designed to replace the complicated operation algorithm. Consequently, this proposed beat segmentation algorithm uses only simple operation such as accumulation and shift operation. And moreover, the decision rule is not complicated as the previous method. The test results show that more than half of tested signals return higher compression ratio (CR). In addition, almost quarter of tested signals have better performance of percent root mean square difference (PRD). Therefore this is the alternative method for the best comparing selection.
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The estimation of GFR and ERPF using adaptive edge-based active contour for the segmentation of structures in dynamic renal scintigraphy
(2015-01-01)
Suapang, Piyamas
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Dejhan, Kobchai
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Yimman, Surapun
Dynamic renal scintigraphy is usually applied for the estimation of GFR and ERPF. The clearance of 98mTc-DTPA and 99mTc-MAGS were the relatively index of GFR and ERPF in the clinical evaluation of patients with acute and chronic renal failure using camera-based methods. In camera-based methods it is necessary to manually delineate ROIs for 99Tc-DTPA and 99m Tc-MAG3 calculation. The requirement may reduce the convenience and reliability of estimating GFR and ERPF from dynamic renal scintigraphy. This paper proposes the estimation of GFR and ERPF using adaptive edge-based active contour for the segmentation of structures in dynamic renal scintigraphy. The salient feature of proposed method is based on combining three other external force. First, the adaptive elastic parameter has been developed to automatically adjust the rigidity of the snake during its evolution towards an image contour. Second, the adaptive balloon force has been implemented to increase the GVF snake's captured range and convergence speed. Finally, a dynamic GVF force is introduced to provide an efficient evolution stop mechanism. Preliminary segmentation results demonstrate the potential of proposed method and are visually judged to be acceptable for clinical use in comparison with the original GVF snake method and manual segmentation by experts. Furthermore, the mean of estimating GFR and ERPF with the proposed method are successfully predicted and do not differ from APEX-XPERT program at the 5% level of significance.
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Weighted least-squares design of variable recursive digital filters with guaranteed stability
(2013-12-31)
Deng, Tian Bo
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Chivapreecha, Sorawat
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Dejhan, Kobchai
The stability guarantee is the most important issue in designing variable infinite-impulse-response (IIR) digital filters. This paper presents a new variable substitution method for transforming the denominator coefficients of a variable-IIR-filter into another set of variables such that arbitrary values of the new variables can guarantee the stability of the resulting variable-IIR-filter. That is, the design problem subject to stability guarantee (constrained non-linear design problem) is converted into an unconstrained design problem. As a consequence, the resulting variable-IIR-filters are always guaranteed theoretically. A lowpass variable-IIR-filter design example is given to illustrate the effectiveness of the design formulation. © 2013 IEEE.
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Single-input multiple-output tunable log-domain current-mode universal filter
(2013-08-27)
Prommee, Pipat
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Dejhan, Kobchai
This paper describes the design of a currentmode single-input multiple-output (SIMO) universal filter based on the log-domain filtering concept. The circuit is a direct realization of a first-order differential equation for obtaining the lossy integrator circuit. Lossless integrators are realized by log-domain lossy integrators. The proposed filter comprises only two grounded capacitors and twentyfour transistors. This filter suits to operate in very high frequency (VHF) applications. The pole-frequency of the proposed filter can be controlled over five decade frequency range through bias currents. The pole-Q can be independently controlled with the pole-frequency. Nonideal effects on the filter are studied in detail. A validated BJT model is used in the simulations operated by a single power supply, as low as 2.5 V. The simulation results using PSpice are included to confirm the good performances and are in agreement with the theory.
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Voltage-mode multifunction biquadratic filters using new ultra-low-power differential difference current conveyors
(2013-08-27)
Kumngern, Montree
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Khateb, Fabian
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Dejhan, Kobchai
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Phasukkit, Pattarapong
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Tungjitkusolmun, Supan
This paper presents two low-power voltagemode multifunction biquadratic filters using differential difference current conveyors. Each proposed circuit employs three differential difference current conveyors, two grounded capacitors and two grounded resistors. The low-voltage ultra-low-power differential difference current conveyor is used to provide low-power consumption of the proposed filters. By appropriately connecting the input and output terminals, the proposed filters can provide lowpass, band-pass, high-pass, band-stop and all-pass voltage responses at high-input terminals, which is a desirable feature for voltage-mode operations. The natural frequency and the quality factor can be orthogonally set by adjusting the circuit components. For realizing all the filter responses, no inverting-type input signal requirements as well as no component-matching conditional requirements are imposed. The incremental parameter sensitivities are also low. The characteristics of the proposed circuits are simulated by using PSPICE simulators to confirm the presented theory.
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Electronically tunable voltage-mode universal filter with single-input five-output using simple OTAs
(2013-08-01)
Kumngern, Montree
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Suwanjan, Peerawut
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Dejhan, Kobchai
This article presents a new electronically tunable voltage-mode universal biquadratic filter with single-input five-output using simple operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed configuration provides low-pass, band-pass, high-pass, band-stop and all-pass voltage responses at a high-impedance input terminal that enables easy cascading in voltage-mode. The natural frequency and the quality factor can be set orthogonally by adjusting the circuit components. The natural frequency can also be controlled electronically by adjusting the bias currents of the OTAs. For realising all the five standard filtering functions, no critical-matching conditions are imposed and all the incremental parameter sensitivities are low. Experimental and simulation results that confirm the theoretical predictions are given. © 2013 Copyright Taylor and Francis Group, LLC.
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Tunable sinusoidal oscillator using CCII with variable current gain
(2013-01-01)
Kumngern, Montree
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Phatsornsiri, Punnavich
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Dejhan, Kobchai
This paper presents a new electronically tunable sinusoidal oscillator. The proposed oscillator is consisted of two second-generation current conveyors with variable current gain, two grounded capacitors, one grounded resistor and one floating resistor. Unlike previously oscillators, the condition and the frequency of oscillation of this oscillator can be controlled electronically and independently by adjusting the current gains of current conveyors. The proposed circuit is beneficial to monolithic integrated circuit implementation using only grounded capacitors. Simulation results that confirm the theoretical predictions are also given. © 2013 IEEE.
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DDCCTA-based quadrature oscillator
(2013-01-01)
Kumngern, Montree
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Auttaput, Anusorn
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Dejhan, Kobchai
This paper presents a voltage-mode quadrature oscillator employing a differential difference current conveyor transconductance amplifier and all-grounded passive devices. The use of grounded passive devices makes the proposed circuit ideal for integrated circuit implementation. The oscillating condition and frequency of the circuit can be controlled orthogonally by the circuit component. The circuit also offers an electronic control of the oscillating frequency through adjusting the bias currents of active devices. The theoretical results are verified by PSPICE simulators. © 2013 IEEE.
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Four inputs and one output current-mode multifunction filter using CDTAs and all-grounded passive components
(2012-12-01)
Kumngern, Montree
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Phatsornsiri, Punnavich
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Dejhan, Kobchai
This paper presents a new current-mode universal filter with four inputs and one output using four current differencing transconductance amplifiers, two grounded capacitors and two grounded resistors. The proposed circuit can realize of low-pass, band-pass, high-pass, band-stop and all-pass current responses, without component-matching conditions and inverting-type input signals requirements. The natural frequency and the quality factor can be set orthogonally and electronically by adjusting the transconductance gains. The filter also offers the features of low input and high output impedances, low active and passive sensitivities and use of only grounded passive components which is ideal for integration point of view. The characteristics of the proposed circuit are simulated using PSPICE simulators to confirm the presented theory. © 2012 IEEE.
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Capacitor-grounded electronically tunable voltage-mode OTA-C multifunction filter with three inputs and five outputs
(2012-12-01)
Kumngern, Montree
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Dejhan, Kobchai
This paper presents an electronically tunable versatile multifunction voltage-mode biquadratic filter with three inputs and five outputs employing five operational transconductance amplifiers, two grounded capacitors and one grounded resistor. The use of grounded capacitors makes the circuit highly suitable for integrated circuit implementation. The proposed filter can simultaneously realize low-pass, band-pass, high-pass, band-stop and all-pass voltage responses by appropriately connecting the input and output terminals. The natural frequency and the quality factor can be orthogonally controlled. No inverting-type input signals are required for realizing all the filter responses, and all the incremental sensitivities are low. PSPICE simulation results are given to confirm the presented theory. © 2012 IEEE.

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