Puttarak, Nattakan
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Puttarak, Nattakan
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Puttarak, N.
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nattakan.pu@kmitl.ac.th
15 results
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Item type:Publication, An implementation of low-density MDS array codes for data protection in distributed network data storage system(2016-09-07); Kaewprapha, PhisanWe present an implementation of disk arrays(RAIDs) in distributed networked data storage environment by applying an error-correcting to accommodate fault tolerance feature. Any of the current state-of-the-art distributed file systems, such as MooseFS [1], can be used as an underlying data space where low density-MDS (Maximum distance separable-Low density parity check) array codes [3] is used as a logical protection layer implemented through FUSE interface (File System In User Space). The redundancy/parity scheme is based on graph structures leading to an MDS code, then can be simply implemented in a parity matrix (H matrix) of an LDPC code. The ability of error correction and data recovery is shown as the bit-error rate (BER) has been investigated. It achieves the same trend compared to the simulation results in [3]. The low-density MDS array code can mitigate hardware failure at higher disk space efficiency comparing to the repetition code. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Network localization using tree search algorithm(2016-09-06) ;Kaewprapha, Phisan ;Tansarn, Thaewawe consider a network localization problem by modeling this as a unit disk graph where nodes are randomly placed with uniform distribution in an area where connectivity between nodes are defined when the distances fall within a unit range. Under a condition that a number of nodes know their locations (anchor nodes), this paper proposes a heuristic approach to find a realization for the rest of the network by applying a tree search algorithm in a depth-first-search manner utilizing graph properties to speed up the search, aka pruning the search tree by modeling an evaluation function from those properties. The evaluation function is used to select the order of the unknown nodes to iterate to. In [1,2], it is demonstrated that number of connections to previously localized nodes reduces the average feasible iterations within reasonable time. This paper also extends the idea further by accommodating various other properties of graph into the evaluation function. The results show that node degrees, node distances and shortest paths to anchor nodes drastically improve the number of iterations required for realizing feasible localization instance by 40%. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Track mis-registration detection using correlation functions in magnetic recording(2012-12-01); ; Track mis-registration (TMR) causes the asymmetric inter-track interference which degrades the system performance. In this work, we propose a TMR detection method based on the cross-correlation functions in bit patterned media (BPM) recording systems. Firstly, the coefficients of the channel are predicted with the cross-correlation functions between the readback signals and the recorded bit sequences on the main track as well as the interfering tracks. Using the ratio of the channel coefficients, the presence and direction of TMR and can be predicted more accurately. © 2012 DSI. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Non-invasive Optical Blood Glucose Measuring System using Regression Models(2023-01-01); ;Seemavijai, Mayravee ;Pongmee, Narutchai ;Kanayat, PannitaDiabetes is one of the chronic diseases with an increasing number of patients every year. Therefore, blood glucose level (BGL) is an essential health information for diagnosis and management of diabetes. Commonly, the BGL is usually measured invasively by taking blood samples, which can cause pain or discomfort to the patients. Our paper aims to design and develop a low-cost, low-computational non-invasive blood glucose measuring system using optical technique. The proposed system consists of a hardware for measuring photoplethysmogram (PPG). The PPG signal is subsequently analyzed to estimate the corresponding BGL, which is sent wirelessly to be stored in a database and displayed on an Android application. The application recommends the appropriate dosage of insulin injection based on the type of users and their diets. The report of historical blood glucose levels in the database can also be generated for further medical examination.Three PPG features, namely peak-to-peak amplitude, maximum amplitude, and standard deviation of signal amplitude, have the strongest correlations to the BGL. We investigate three regression models for estimating the BGL from these PPG parameters. The robustness of the system is assessed using cross validations. The average root mean squares error (RMSE) for three-fold cross-validations are 17.38, 16.76, and 16.39 mg/dL for simple linear regression, principal component regression, and partial least squares regression, respectively. The RMSEs from leave-one-out cross validation are approximately 12 mg/dL, with partial least squares regression model having the best accuracy. Furthermore, the results from Clarke Error Grid Analysis indicate that the system can be implemented with any of the three models for practical usage. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Low-density MDS array codes based on rigid graph structure(2014-10-15); Kaewprapha, PhisanIn data communications system including wired and wireless transmissions, the reliability, integrity, speed, and cost efficiency are the main issues that people desire. An error correcting code is one of the efficient and nearly-optimal methods to improve the system performance. Based on the idea of constructing MDS codes called CGR codes in [3] for disk arrays, this paper introduces a new perspective and construction of LDPC codes due to its sparsity and advantage complexity in implementation. The performance of this code in Additive White Gaussian Noise (AWGN) and fading channels gains about 1.0 dB at the 10<sup>-3</sup> of bit error rate (BER) compared with an EVENODD code. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Cardiac Arrhythmia Teletriage using Electrocardiogram(2021-01-01); ;Chokchaichumnankit, Thunchanok ;Sanguanchom, Jirayu ;Soyphan, NatchanonTelehealth has become a favorable method for receiving medical care during the COVID-19 pandemic. It reduces physical contact and also benefits those who live a distance from hospitals. In this paper we present a cardiac arrhythmia teletriage using electrocardiogram (ECG). The system consists of a diagnostic algorithm for arrhythmias and an Android application. The diagnostic algorithm can detect five types of cardiac problems-arrhythmia, bradycardia, tachycardia, bradyarrhythmia, and tachyarrhythmia. The Android application is the main communication channel between patients and healthcare providers. The user uploads their ECG and receives a preliminary diagnosis of their heart health via the application. The system notifies the user if it detects any abnormalities. The user can then make an appointment online for further examination at the hospital. The capability of the proposed system is evaluated using four databases from PhysioNet - MITBIH Normal Sinus Rhythm Database, MIT-BIH Arrhythmia Database, MIT-BIH Atrial Fibrillation Database, and CU Ventricular Tachyarrhythmia Database. It is found that the algorithm is able to detect abnormal ECG signals with an average accuracy of 82.1%. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Reference Signal Received Power Prediction Using Convolutional Neural Network with Residual Loss(2023-01-01) ;Ngenjaroendee, Thearrawit; ;Wijitpornchai, Thongchai ;Areeprayoonkij, PoonlarpJaruvitayakovit, TanunIn this paper, LTE measurement reports collected from user equipments are used to generate the residual loss, which can represent the loss value of each grid. The residual loss and geospatial data are used in the learning process of convolutional neural network (CNN). We also use the site configuration and three-dimensional antenna pattern. Thus, the neural network and convolutional neural network are proposed to construct deep learning to predict the reference signal received power (RSRP) in Bangkok, Thailand. The results show that residual loss can improve the efficiency of prediction. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A short-term rain-induced attenuation model for satellite link quality prediction(2014-01-01) ;Poolsawut, Jirutchaya; This paper proposes a novel but simple satellite link quality prediction based on the relationship between rainfall rate and satellite signal attenuation. After quantifying their relationship statistically, we describe their contemporaneous variations using a linear dynamical system response model. The expectation-maximization (EM) algorithm is used to obtain the maximum likelihood estimates of the model parameters. Subsequently, the communication link quality is predicted by thresholding the estimated short-term signal attenuation level obtained from the Expectation step of the EM algorithm. The prediction performance of the proposed method is compared against the measured beacon signals from Thaicom-4 (IPSTAR) satellite during rainfalls. Using solely the observed rainfall rates from a tipping bucket rain gauge, the algorithm is able to decently predict the satellite link quality. We believe the proposed model can be modified as a predictive tool for real-time link unavailability monitoring of satellite communication system. © 2014 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An implementation of maximum likelihood decoder for error-file recovery on cloud storage system(2018-07-02) ;Sangprasittichok, PakpoomCloud storage system is a distributed storage system which stores data in many disks on the Internet. In order to achieve more reliable data and improve performance of the storage system, an erasure code is invented and applied to cloud storage system wherein the user's data will be stored online through the Internet. This paper applies the complete graph of ring (CGR) codes [7], which is a maximum distance separable (MDS) code, and implements in cloud storage system. Moreover, the maximum likelihood decoder (MLD) is also applied and implemented on the receiver to detect and correct errors due to noisy channel. In this paper, the grey-scale images/files are randomly stored on distributed cloud storage, then sent via communications channel, and finally read by receivers. The result shows that the receiver operated with the MLD outperforms by giving the lower BER. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Designed MMSE equalizers for nonlinear magnetic recording channels(2014-01-01) ;Sirirungsakulwong, Atitaya; Writing process in hard disk drives (HDD) is affected from nonlinearity. Normally, nonlinearity is not easy to be avoided or removed since it is unexpected and caused by various sources. In this paper, we review a description of a nonlinearity behavior by using a Volterra model, and using a random binary number to generate an input data. The Volterra model can describe both linear and nonlinear parts of the read-back signals in terms of the volterra equations. In addition, we propose to use an MMSE method to equalize the read-back signals with nonlinearity using various constraints before applying the Viterbi detector. For a 2nd-order Volterra model, the results show that the equalizer with g<inf>1</inf> =1 constraint gives the lowest MMSE values. Furthermore, as the nonlinearity level increases, the bit error rate (BER) performance degrades. © 2014 IEEE.
