Tuwanut, Panwit
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Tuwanut, Panwit
Alternative Name
Tuwanut, P.
Tuwanuti, Panwit
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panwit.tu@kmitl.ac.th
28 results
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Item type:Publication, Breathing sound detection from the external auditory canal with condenser microphones(2021-05-19); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, New pulse oximetry detection based on the light absorbance ratio as determined from amplitude modulation indexes in the time and frequency domains(2022-05-01); ; The Pandemic COVID-19 situation, a pulse Oximetry is significant to detect a varying blood oxygen saturation of a patient who needed the device to operate with continuous, rapid, high accuracy, and immune of moving artifacts. In this article, three main schemes for low-complexity pulse oximetry detection are proposed. In the first scheme, the light absorbance ratio (R) is obtained by separating the red and infrared photoplethysmography (PPG) amplitude modulation (AM) signals from the frequency-division multiplexing (FDM) signal with two different bandpass filters (BPFs), determining the ratio of modulation index of red and infrared PPG AM signals. In the second scheme, the output PPG AM signals for the red and infrared light wavelengths from the BPFs are transformed into the frequency domain such that the AC components of both PPG AM signals are the magnitudes of the highest peaks in their respective sidebands, while the DC components are the magnitude of their carrier frequencies; then, the AC/DC ratio of the red PPG AM signal is divided by the AC/DC ratio of the infrared PPG AM signal is R. In the last scheme, the FDM signal is transformed into the frequency domain without being passed through any BPF, and R is obtained in the same way as in the same second scheme. Experimental results obtained by using the first scheme have an average error of about 0.7138%, for the second and the last scheme have an average error of about 1%, and all the methods agree with the corresponding mathematical model. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Pulse Oximetry Based on Quadrature Multiplexing of the Amplitude Modulated Photoplethysmographic Signals(2023-07-01); ; ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Practical Circuit of Cyclic Chirp Spread Spectrum Modulation for Long Range Communication(2022-01-01); ; ; Various technologies have been utilized in long range communication to satisfy increasing usage of the internet of things in a wide large area. Recently, a modulating technique called cyclic chirp spread spectrum (CSS) modulation has attracted attention due to its low power usage and long-range coverage. However, a cyclic CSS circuit is complex to build. Hence, the objective of the work is to propose a practical circuit of cyclic CSS modulation. The proposed circuit is designed to complicated-free creation. To prove that the presented circuit is pragmatic, a simulation test is performed. The simulation results have illustrated that the designed circuit well generates a chirp modulating signal. Also, the proposed circuit is flexibly configurable. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An Image Resizing Function Embedded in an Inverse Discrete Cosine Transform(2022-01-01); Image resizing is an everyday activity and can be done in either a spatial domain or a transform domain. This work realizes that an image is commonly stored in the transform domain and the transformed image must be converted back to the spatial domain to display. This work hence proposes embedding an image resizing function based on a scaled frequency (SF) in a matrix operation of inverse discrete cosine transform (IDCT) for the sake of convenience. By adopting the proposed technique called as the SF-IDCT is not only capable of resizing the transformed image to a given resolution, but also acquiring the IDCT as a by-product. Image data can be shortened or lengthened in proportion to their frequencies by varying the frequencies of the DCT basis functions. Besides, the effects of modifying the pattern of the image data are also studied. The experimental results indicate that the SF-IDCT functions well. The proposed technique reconstructs an upsized image of equal or better visual quality than those produced by existing methods. For a downsized image, the performance of the presented approach is competitive with other available methods. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of Light Intensity on a Motion Artifact Signal in a Photoplethysmographic Signal(2018-11-27); ; A photoplethygraphic (PPG) signal acquired from a commercial pulse oximeter is habitually disfigured by a motion artifact (MA) signal while any motion takes place. Inherently, the MA signal can either be additive or multiplicative, By having the MA signal intertwined with the PPG signal, the estimate of the oxygen saturation (SpO2) value is unreliable. The computation of SO02 value is based on proper red and infrared (IR) PPG signals measured by the pulse oximeter. Generally, the frequency components of the red and IR PPG signals as well as the MA signal are in the same range. To overwhelm this problem, the frequency components of the red and IR PPG signals are severed from the frequency band of the MA signal. To implement the separation, a legacy source of driving red and IR LEDs in the pulse oximeter is replaced by two alternating current sources having different frequencies. With this solution, the additive MA signal is no longer involved but the multiplicative MA signal is yet not concluded. In this work, change in light intensity fed to both red and IR LEDs is studied whether the changed light intensity has any impact on the multiplicative MA signal. According to the study, it is found that change in light intensity does not affect the multiplicative MA signal. The multiplicative MA signal still exists since the overall calculated SpO2 values have some error up to 1 %. Besides, change in light intensity does not improve the quality of the estimated SpO2 values while resting. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, New analytic solution of second-order oscillator using multi-time variables technique(2005-01-01); ; In this paper, a new analysis of sinusoidal oscillator amplitude controlled by forced response using the second order differential equation (ODE) is proposed. In general, the amplitude of the complete response is derived where forced response slope is normally assumed to be zero. The value of forced response only at initial time is thus employed to determine the amplitude. But if forced input is dynamic signal the amplitude of complete response gained by using such assumption is different from the experimental result. Thus, a new analysis of amplitude for a dynamic forced response is proposed in this paper. It is found that the forced response at any arbitrary time (not only at the initial time) is presented in a term of natural response magnitude. Magnitude of natural response is therefore directly controlled by forced response. To confirm the theoretical analysis, experimental results have been demonstrated and agreed well with the analysis results. © 2005 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A simple and economic PWM and ΣΔ modulator circuit based on modified source-couple oscillator(2006-01-01); ; In this article, a simple and economic Pulse Width Modulator (PWM) and Sigma Delta Modulator (ΣΔ) circuit which is based on the modified CMOS source couple voltage-control oscillator is presented. The circuit can work either as PWM or ΣΔ modulator, depending on the condition of the two bias currents which are forced of the source couples. Namely, the circuit is a PWM when these two bias currents are out of phase. Otherwise, it is a ΣΔ modulator when both bias currents are identical. In addition, another feature of the proposed circuit is that the modulated signal can be either in voltage or current format. Moreover, the proposed circuit provides wide range of frequency operation because of few numbers of CMOS in the circuit. Furthermore, the circuit is very suitable for realization in integrated circuits (ICs) form and can be employed for optical communication application. The simulation results of the circuit are demonstrated and agreed well with theoretical anticipation. © 2006 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental performance evaluation of LoRaWAN: A case study in Bangkok(2017-09-05); The Internet of Things (IoT) is a vision which real-world objects are part of the internet. Every object is uniquely identified, and accessible to the network. There are various types of communication protocol for connect the device to the Internet. One of them is a Low Power Wide Area Network (LPWAN) which is a novel technology use to implement IoT applications. There are many platforms of LPWAN such as NB-IoT, LoRaWAN. In this paper, the experimental performance evaluation of LoRaWAN over a real environment in Bangkok, Thailand is presented. From these experimental results, the communication ranges in both an outdoor and an indoor environment are limited. Hence, the IoT application with LoRaWAN technology can be reliable in limited of communication ranges. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, EORL: Energy Optimization via Reinforcement Learning in Software-Defined Wireless Sensor Networks(2024-01-01); ; Tanessakulwattana, SarayootA wireless sensor network is a collection of sensors placed in a particular area to collect and transmit data to the base station or sink. They usually have batteries as the primary power sources. If they work for a long time, their energy will be exhausted. Replacing the battery may not be cost-effective compared to developing an algorithm that optimizes energy efficiency to extend the network lifetime. This work optimizes the energy consumption of wireless sensor networks by adaptively selecting an optimal routing path in a Software-defined Wireless Sensor Networks (SDWSN) environment. A concept of the energy balance among nodes according to the current network status by the SDWSN controller using Reinforcement Learning (RL) is introduced. We propose energy optimization via reinforcement learning (EORL) for SDWSN using a minimum energy reward function and state design that considers energy consumption. The EORL algorithm then identifies the node that requires attention and selects the most energy-efficient path for that node. The performance of the EORL shows that it has a more extended network lifetime compared with other RL solutions.