Thumwarin, Pitak

Preferred name

Thumwarin, Pitak

Alternative Name

Thumwarin, P.

Main Affiliation

Music Science and Engineering

pitak.th@kmitl.ac.th

Now showing 1 - 10 of 31

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An adaptive generalized RAKE CDMA receiver for layered space time coded systems in multipath fading channels
(2010-07-30)
Keovkolyan, T.
;
Nugrahani, D.
;
Thumwarin, P.
;
Teekapakvisit, C.
;
Matsuura, T.
An adaptive generalized RAKE receiver for Layered Space Time Coded CDMA (LSTC-CDMA) system has been proposed in this paper. The proposed Generalized RAKE receiver, based on a joint adaptive iterative detection and decoding algorithm, adaptively mitigates the effect of multipath fading and cancels the system interferences such as Co-Channel Interference (CCI) and Multiple Access Interference (MAI). The Partially Filtered Gradient Least Means Square (PFGLMS) algorithm is used for both feed-forward filter and feedback filter in the adaptive detection in order to determine the weight coefficient of each finger element. The performance of the system is evaluated by simulation results for the various numbers of RAKE fingers in multipath Rayleigh fading channels.
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On-line writer recognition for Thai numeral
(2002-01-01)
Thumwarin, P.
;
Tangtisanon, P.
;
Murata, S.
;
Matsuura, T.
This paper discusses an on-line writer recognition for Thai numerals. First, a center point of a Thai numeral is determined after normalization. Then the center point is shifted to an origin. Secondly, the distance from the origin to the pen-point position in the handwriting process is measured and the area of a triangle determined from the origin and the two adjacent points of the pen-point position is calculated. Thirdly, the features of pen-point movement in the process are extracted by expanding the time sequence of the above distance and area into Fourier series. Then the features of pen-point movement are represented in terms of Fourier coefficients. Fourthly, in order to describe the handwriting process features, the FIR system with the above coefficients as input and output of the system is introduced. Then the impulse response of the FIR system is used as the feature of handwriting process. Furthermore in order to recognize the writer, K-L expansion (J.T. Tou and R.C. Gonzalez "Pattern Recognition Principles", Addison-Wesley, pp. 269, 1974) of the obtained impulse response is used. In the experiments, the average rates of type I (false rejection) and type II (false acceptance) error were 17.14% and 9.26%, respectively.
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FIR firearm identification system
(2009-01-01)
Thumwarin, P.
;
Prasit, C.
;
Suwanvesh, T.
;
Matsuura, T.
We propose a FIR(Finite impulse response) firearm identification system. The firearm can be identified by using the impulse response of the FIR system characterizing the rotation invariant feature of the cartridge case image. In this case, the rotation invariant feature can be extracted by the magnitude of Fourier coefficients of polar image of the cartridge. Then the obtained Fourier coefficients are used as the input and the output of the FIR system. The impulse response of the FIR system is used as the unique feature for firearm identification. Finally, the firearm can be identified by the Fisher's linear discriminant function. The experimental results are taken to show the effectiveness of the proposed method.
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On-line writer dependent character recognition for Khmer based on FIR system characterizing handwriting motion
(2008-12-01)
Thumwarin, Pitak
;
Khem, Sochenda
;
Janchitraponvej, Kanok
;
Matsuura, Takenobu
We propose an on-line writer dependent Khmer recognition method based on time-frequency characteristics of handwriting motion. The handwriting motion can be described by two features, barycenter trajectory and its velocity of pen-tip movement. Then the barycenter trajectory and its velocity of the pen-tip movement are expanded into wavelet series to extract the time-frequency characteristics of the handwriting motion. After that, The fluctuation of the wavelet coefficients can be reduced by the FIR(Finite Impulse Response) Wiener filter. Moreover, the FIR system characterizing the time-frequency characteristics of the handwriting motion is introduced by using wavelet coefficients of the velocity and trajectory of the barycenter with fluctuation reduced as the input and output of the FIR system, respectively. The obtained impulse response of the FIR system is considered as the individual feature for a particular character. Finally, Khmer alphabets can be recognized by using the Euclidean distance between the impulse responses obtained from the reference alphabets and those of the alphabets to be recognized. Khmer character recognition experiments were performed on a database consisting of 6,750 of numerals and alphabets written by 17 people. As the results, the average of the recognition rate was 98.17%. © 2008 SICE.
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Firearm identification system with rotation invariance
(2010-01-01)
Thumwarin, P.
;
Prasit, C.
;
Yakoompai, K.
;
Matsuura, T.
This paper presents a firearm identification method with rotation invariance. The rotation invariant feature can be extracted by the magnitude of Fourier coefficients of polar image of the cartridge on circles with different radii. Then the fluctuation of the obtained magnitude of Fourier coefficients can be reduced by the FIR(Finite impulse response) Wiener filter. And they are used as the input and the output of the FIR system characterizing the rotation invariant feature of cartridge image. The impulse response of the FIR system is used as the unique feature for firearm identification. Finally, the firearm can be identified by the Fisher's linear discriminant function. The experimental results are given to show the effectiveness of the proposed method. ©ICROS.
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On-line writer identification system characterizing velocity and areal velocity in handwriting process
(2009-12-01)
Matsuura, Takenobu
;
Thumwarin, Pitak
In this paper,we propose an on-line writer identification system characterizing velocity and areal velocity of pen-tip movement in handwriting process. The writer identification system consists of two finite impulse response (FIR) systems characterizing the velocity and areal velocity in handwriting process. Individual handwriting feature is represented by the impulse response of the FIR system. Writer can be identified by evaluating the difference between the impulse responses of the FIR systems for the reference and a person to be identified. In our experiments 2,000 Thai numerals were used to identify 10 different writers.
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Wide-band slot antenna for IEEE 802.11b/g
(2006-12-01)
Kueathawikun, W.
;
Thumwarin, P.
;
Anantrasirichai, N.
;
Wakabayashi, T.
This paper presents coplanar waveguide (CPW) fed step slot antenna. It achieves wide band from 2.0 GHz to 4.2 GHz which is the frequency band covered the standard IEEE 802.11b/g (2.4 - 2.485 GHz) for use in WLAN (Wireless Local Area Network) and covered two frequencies of WiMAX (Worldwide Interoperability for Microwave Access) 2.5 GHz and 3.5 GHz. The characteristics of antenna are proposed and analyzed for instance input impedance, return loss and far field radiation patterns. © 2006 ICASE.
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On-line signature verification based on FIR system characterizing velocity and direction change of barycenter trajectory
(2010-12-01)
Thumwarin, P.
;
Pernwong, J.
;
Wakayaphattaramanus, N.
;
Matsuura, T.
We propose an on-line signature verification method based on finite impulse response(FIR) system characterizing velocity and direction change of barycenter trajectory. First, the discrete cosine transforms (DCTs) of the characteristics are used to reduce fluctuation and extract the feature of handwriting in signing process. Then the signature verification system is realized by the three FIR subsystems. The obtained impulse responses of the three FIR subsystems are used as the individual feature for signature verification. Signature can be verified by evaluating the difference between the impulse responses of the FIR subsystems for a reference signature and the signature to be verified. The signature verification experiments were performed on the SUBCORPUS-100 MCYT signature database[6] consisting of 5,000 signatures from 100 signers. ©2010 IEEE.
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A robust coin recognition method with rotation invariance
(2006-12-01)
Thumwarin, P.
;
Malila, S.
;
Janthawong, P.
;
Pibulwej, W.
;
Matsuura, T.
This paper presents a robust coin recognition method with rotation invariance. The rotation invariance feature is represented by the absolute value of Fourier coefficients of polar image of coin on circles with different radii. The absolute value of Fourier coefficients is considered as the individual feature of the particular coin. Moreover, in this paper, the variations on surface of coin such as light reflection effect, are taken into account. Such variations effect can be reduced using the Fourier approximation of the coin image. Finally, coin can be recognized by the distance between the absolute value of Fourier coefficients obtained from the reference coin and the coin to be recognized. The coin recognition experiments are given to show the effectiveness of the proposed method. © 2006 IEEE.
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On-line signature verification based on FIR system characterizing motion pressure
(2011-12-01)
Thumwarin, P.
;
Pernwong, J.
;
Matsuura, T.
We propose an on-line signature verification method based on finite impulse response(FIR) system characterizing motion pressure of pen-point trajectory in signing process. The discrete cosine transforms(DCTs) of the handwriting feature is used to reduce the fluctuation and extract the feature of handwriting. The signature verification system is realized by four FIR subsystems. Then motion pressure can be characterized by using the FIR subsystem having the DCTs of the area pressure and motion pressure as the input and the output of the FIR system, respectively. The obtained impulse responses of the four FIR subsystems are used as the individual feature for signature verification. Finally, the signature can be verified by evaluating the difference between the impulse responses of the FIR subsystems for a reference signature and the signature to be verified. The signature verification experiments were performed on the SUBCORPUS-100 MCYT [J. Ortega-Garcia et al. 2003] signature database consisting of 5,000 signatures from 100 signers. The propose method yielded equal error rate(EER) 4.38 % on skilled forgeries. © 2011 ACM.

Thumwarin, Pitak

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