Tuntrakool, Sunti

Preferred name

Tuntrakool, Sunti

Alternative Name

Tuntrakool, S.

Main Affiliation

School of Industrial Education and Technology

sunti.tu@kmitl.ac.th

Now showing 1 - 10 of 18

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Quadrature oscillator with independent frequency control using ECCIIs
(2015-01-26)
Kumngern, Montree
;
Tuntrakool, Sunti
This paper presents a new mixed-mode quadrature oscillator. The proposed structure employs two electronically tunable second-generation current conveyors, two grounded capacitors and three grounded resistors which is suitable for integrated circuit implementation. Unlike previously oscillators, both the condition of oscillation and the frequency of oscillation of the proposed oscillator can be controlled using resistors and/or current-gain of ECCII. The circuit provides two quadrature current outputs and two quadrature voltage outputs. The current output terminals also possess high-impedance level which can be directly connected to the next stage without additional buffer circuits. PSPICE simulation results are given to confirm the workability of the proposed structure.
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Polarization insensitive switchable metamaterial absorber/reflector for x-band applications
(2020-01-01)
Mustapha, M. G.
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Rahim, M. K.A.
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Murad, N. A.
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Ayop, O.
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Tuntrakool, S.
A unit cell of squared shaped polarization-insensitive switchable metamaterial absorber/reflector is presented. The structure operates at 10.20 GHz under both absorber mode and reflector mode configurations. Copper wire bridging the gaps to form a circular shape structure were used as switches for operation mode selections. The structure was designed on an FR4 substrate, and the incidental wave angles were varied from 0 to 50 degrees. The structure demonstrated almost 100% absorption at resonance, 3.314 GHz percentage bandwidth at 80% as an absorber. On the other hand, as reflector, it demonstrated almost a 90% reflection and a usable bandwidth of 3.327 GHz.
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Broadband Reflective Metasurface at X-band Frequency Using Snowflakes Fractal Ring Design
(2025-01-01)
Yaziz, Nur Syahirah Mohd
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Rahim, Mohamad Kamal A.
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Samsuri, Noor Asmawati
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Zubir, Farid
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Tuntrakool, Sunti
A broadband reflective metasurface has been designed to integrate inward and outward fractal Koch rings operating at X-band frequencies. The integration between the inward and outward fractal Koch ring creates the snowflake fractal shape that operates at a center frequency of 10 GHz. Based on the simulated results, the reflection values are 0.9 with the reflection phase of 1800 which is between 900 to -900. Overall, all resonance frequencies exhibit more than 90% reflected power, with bandwidth of 1.90 GHz that cover from 8.70 GHz to 10.60 GHz.
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Dual-Band Reflective Metasurfaces for 5G mmWave Applications: Design, Analysis, and Waveguide Validations
(2026-01-01)
Mohammed, Sunusi Garba
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Samsuri, Noor Asmawati Binti
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Rahim, Mohamad Kamal B.A.
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Ripin, Nabilah Binti
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Taufiqqurrachman
This paper presents a dual-band reflective metasurface unit cell for millimeter-wave RIS applications operating at 26 GHz and 28 GHz, covering the 5G n258 and n257 bands. The proposed design features a hybrid resonator structure to achieve a consistent phase trend and strong reflection performance across the 5G mmWave frequency band. To ensure stable dual-band performance of the unit cell, parametric optimization is conducted. The unit cell is investigated through Floquet simulations and WR-34 rectangular -to-square waveguide-transition-based full-wave simulations, followed by experimental validation using a fabricated WR-34 rectangular-to-square waveguide transition. The simulated resonances at 26 GHz and 28 GHz are experimentally observed at 26.7 GHz and 28.9 GHz, respectively, indicating minor frequency deviations. Measured results demonstrate reflection magnitudes of -1.80 dB at 26.7 GHz and -0.80 dB at 28.9 GHz, with corresponding phase responses of - 68° and -13°, and bandwidths of 5.12% and 6.07%, respectively.
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Integer- And fractional-order VCO using non-inertial amplitude stabilization and modern active elements
(2020-04-28)
Sotner, Roman
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Petrzela, Jiri
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Jerabek, Jan
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Langhammer, Lukas
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Polak, Josef
This paper introduces design of the linearly tunable quadrature voltage-controlled oscillator (VCO) using modern off-the-shelf active elements suitable for the design of electronically adjustable applications. The simplified topology was achieved using non-inertial stabilization of amplitude. It allows targeting adjustability of the oscillation frequency only into lossless integrator part of the topology. This arrangement simplifies the design and the tenability also. Derived symbolical expressions indicate that gain adjustment of used amplifiers (that are still in single path) does not influence amplitude and phase shift ratio of generated waveforms, which is a beneficial feature. The performances of the circuit are tested experimentally in band of units of MHz and results confirmed expected behavior. Initial study of the oscillator with fractional-order capacitors is presented and discussed. Results are supported by laboratory measurements.
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Voltage Differencing Current Conveyor Differential Input Transconductance Amplifier: Novel Active Element and Its Resistorless Filtering Application
(2019-10-01)
Sotner, Roman
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Jerabek, Jan
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Langhammer, Lukas
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Petrzela, Jiri
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Jaikla, Winai
This paper introduces novel modification of active element based on current conveyor transconductance amplifier core abbreviated as current controlled voltage differencing current conveyor differential input transconductance amplifier (CC-VDCCDITA). The active element is implemented by recently developed and manufactured IC modular device based on I3T25 0.35 μm ON Semiconductor CMOS process. Active element uses three internal active cells of this IC device for construction of the CC-VDCCDITA. An application example of proposed element in simple special resistor-less electronically adjustable biquadratic filter is shown. Brief comparison with state-of-the-art solutions indicates beneficial features of proposed solution. Simulation results in Cadence IC tool accompany precise laboratory experimental measurements with real prototype.
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AWC 708C Laser Cutting Manual Learning Set
(2020-09-23)
Sae-Jeng, Wasin
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Tuntrakool, Sunti
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Maunsaiyat, Somchai
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Supavarasuwat, Piya
This research paper presents AWC 708C laser cutting manual learning set. It is a learning set which is relevant to high school courses and taught in a module (namely 30291 Creativity and Innovation). The researchers have developed a combination between the augmented reality technology and the AWC708C laser cutting learning kit to make them more attractive and reduce danger to users by adding additional security systems to the device. Also, it includes teaching how to use the machine through a designed worksheet to accompany with an augmented reality technology which is intended to be suitable for high school students in grade 10 (Mathayomsuksa 4). The results of this research found that overall quality of the AWC 708C laser cutting learning kit is in good quality level with average of 4.48±0.58. Outstanding results from an overall quality assessment are the convenience in preparing the equipment and the simple method of using the machine. Also, the quality level of the worksheet is in good quality level with average of 4.24±0.66. In addition, it was found that the results of the evaluation on satisfaction with the AWC 708C laser cutting machine learning kit is in very good level with average of 4.77±0.42. From the comparison of academic achievement between before and after using the learning set analyzed by t-test, it is found that the pre and post test scores of the sample groups had an average score of 5.50 and 8.96, respectively. From t distribution table which has df = 23, confidence value at 0.05 level with t = 2.707, the analysis result is 15.37 higher than the t distribution table. It is implied that the results of the pre-test achievement were different from the post-test achievement scores with significance level of 0.05. From the research hypothesis, it is found that those who studied with AWC708C laser cutting manual learning set had academic achievement after studied higher than before, according to the assumptions. Hence, in this research it can be concluded that the quality of the AWC 708C laser cutting machine learning kit can be increased.
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High input impedance voltage-mode universal filter and its modification as quadrature oscillator using VDDDAs
(2017-05-01)
Tuntrakool, Sunti
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Kumngern, Montree
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Sotner, Roman
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Herencsar, Norbert
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Suwanjan, Peerawut
The second order universal voltage-mode filter using voltage differencing differential difference amplifiers (VDDDAs) has been proposed. It has high input impedance voltage-mode biquad filter with orthogonal tune of natural frequency and quality factor. The proposed filter simultaneously provides five filter responses: low-pass (LP), high-pass (HP), band-reject (BR), all-pass (AP) and band-pass (BP) in the same circuit topology. The natural frequency and quality factor can be tuned electronically and orthogonally dc bias current. The output impedance at output nodes HP, AP and BR has low impedance which can connect to other circuit without the use of voltage buffers. The proposed filter consists of three VDDDAs, one grounded resistor and two grounded capacitors. This makes the proposed filter suitable for integrated circuit development. With slightly modifying the proposed filter, the voltage-mode qudrature sinusoidal oscillator with low output impedance and independent control of condition of oscillation (CO) and frequency of oscillation (FO) has been achieved. The results shown in this paper are from PSPICE simulation and experiment to validate the proposed circuits.
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A Model of Engineering Education for Innovation
(2018-09-17)
Sunthonkanokpong, Wisuit
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Murphy, Elizabeth
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Tuntrakool, Sunti
The purpose of this paper is to present implications of innovation for Engineering Education (EE) and research. The specific objectives are as follows: Analyze innovation policies from India, Malaysia, Thailand, Korea and the Association of South-East Nations (ASEAN): Identify common themes between policies; determine implications for EE for Innovation (EEFI); create a model of EEFI; determine implications for EEFI research. Analysis of the policies led to the identification of seven themes: prosperity, humanity, inclusivity, capacity, sustainability, inquiry, and community. These themes guided the creation of a model of EEFI. The model consists of four principal bases: learner-based; STEM + AE-based, problem-based and; project-based. Learner-based focuses on what engineers are in terms of their personal and professional competencies. STEM + AE are a reminder that engineers must be more than technicians, well-versed in STEM. Their education needs to include the arts and entrepreneurship. The problem base refers to EEFI activity being driven by complex, authentic, ill-structured challenges, problems and issues that have a social as well as a technical character. The project-base involves collaborative efforts to find answers to questions and create solutions to problems and challenges. Implications for research highlight a range of approaches to researching EEFI from quantitative surveys of perceptions of participants to complex research designs whereby engineers in training are collaboratively solving real problems in communities.
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Comparison between Snowflake Fractal and Koch Fractal for Intelligent Reflecting Surface
(2025-01-01)
Yaziz, Nur Syahirah Mohd
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Rahim, Mohamad Kamal A.
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Samsuri, Noor Asmawati
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Zubir, Farid
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Tuntrakool, Sunti
This paper compares two fractal metasurface designs for Intelligent Reflecting Surfaces at X-band which is with a snowflake-shaped fractal ring and a fractal Koch metasurface. The snowflake ring design with a 10GHz center frequency achieves very high reflectance (~90%) at resonance and a bandwidth of about 1.90 GHz. The Koch-fractal design response with a bandwidth of 2.10 GHz at a center frequency of 10GHz. The method for both fractal metasurfaces and a comparable on their reflection coefficients, phase behaviour, bandwidth and current distributions are discussed in section II and section III.
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Tuntrakool, Sunti

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