Sokjabok, Siwakon

Preferred name

Sokjabok, Siwakon

Alternative Name

Sokjabok, S.

Main Affiliation

KMITL Prince of Chumphon Campus

siwakon.so@kmitl.ac.th

Now showing 1 - 9 of 9

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Symbol-flipping method for block decoding in bit-patterned magnetic recording
(2021-05-19)
Sokjabok, Siwakon
;
Mattayakan, Mutita
;
Warisarn, Chanon
;
Koonkarnkhai, Santi
;
Kovintavewat, Piya
Bit-patterned magnetic recording (BPMR) technology can provide an areal density (AD) up to 15 Terabit per square inch (Tb/in2). However, the consequence of an increased AD results in severe inter-symbol interference (ISI) and inter-track interference (ITI). In practice, a run-length limited (RLL) code can be used to alleviate this problem. Therefore, this research proposes a symbol-flipping method in an iterative detection scheme between a soft-output Viterbi algorithm (SOVA) detector and an RLL decoder to help reduce errors resulting from these two interferences in a BPMR system. Simulation results reveal that the proposed system performs better than the same system architecture without the symbol-flipping method by 0.5 decibels at an AD of 5 Tb/in2.
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Codeword design of a Rate-5/6 for single-reader two-track reading in BPMR systems
(2021-05-19)
Mattayakan, Mutita
;
Sokjabok, Siwakon
;
Warisarn, Chanon
At present, the information storage demand of hard disk drive (HDD) was dramatically increasing every year. However, an increase of an areal density (AD) for bit-patterned media recording (BPMR) seems to be crucial for HDD industry. One of the main problems of BPMR system is two-dimensional interference effect that composes of inter-track interference (ITI) and inter-symbol interference (ISI), which still be the main challenge that we have to flounder to continuously enhance the efficiency of magnetic recording system. Therefore, this paper proposes a rate-5/6 2D modulation code to evolve bit error rate (BER) efficiency of a staggered single-reader two-track reading (SRTR) based BPMR systems. We select all 32 codewords from all 64 considered patterns according to the statistics principle considering. The first 32 patterns that provide the least error-bit number will then be defined as our proposed codewords. These selected patterns can efficiently avoid the forbidden patterns that means it is going to radically suppress both ISI and ITI effects. We simply encode by using a look-up table, while we use the Euclidean distance concept to recover user bits in the decoding process. From the simulation, we found that the proposed method shows a better BER efficiency than both the uncoded and conventional recording systems. Even we add more media noises, this proposed system still provides us with a better performance. Moreover, SRTR scheme offers us more satisfactory capability than the conventional recording systems.
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Study of CNN-Based Data Detection in Dual-Layer Bit-Patterned Magnetic Recording Systems
(2025-01-01)
Sangthong, Siraphop
;
Sokjabok, Siwakon
;
Khametong, Anawin
;
Warisarn, Chanon
This paper introduces an innovative data detection system that utilizes convolutional neural networks (CNNs) for dual-layered bit-patterned magnetic systems. Using a mutual-information CNN architecture, the proposed system tackles the challenge of decoding overlapping readback signals from upper and lower layers. The sliding window detection schemes are implemented with input lengths of 6 (2×3) and 14 (2×7) bits, processing oversampled readback signals from a dataset of 1,000,000 bits. Simulation results conducted over a signal-to-noise ratio range of 10 to 24 dBs indicate that the CNN model with a larger input window significantly outperforms smaller input models and conventional partial response maximum likelihood detectors in terms of bit error rate. These findings illustrate the effectiveness of CNN-based detection in enhancing classification accuracy under high-noise conditions, paving the way for future ultra-high-density magnetic recording systems.
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Fabrication of Eco-Friendly Pineapple Leaf Fiber-Based Vegan Leather for Environmental Sustainability
(2026-01-20)
Srisang, Siriwan
;
Kunyuan, Jumpon
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Hutangkoon, Thunyanat
;
Eiangmee, Orranat
;
Maikaew, Jatuphat
The environmental impact of synthetic leather production has raised global concerns due to its reliance on petroleum-based polymers and poor biodegradability. Therefore, the development of sustainable, eco-friendly alternatives using renewable resources has become increasingly important. A biodegradable vegan leather was developed from natural rubber and pineapple leaf fibers (PALF), with properties analyzed using Response Surface Methodology (RSM). The effects of fiber content (X1), compression time (X2), and compression temperature (X3) were studied on biodegradation (Y1), water absorption (Y2), and tensile strength (Y3). Results showed that all three factors significantly influenced Y1, with the predictive model demonstrating high reliability (R > 90%). The optimum condition for Y1 was X1 = 3.0 g, X2 = 70.0 min, and X3 = 110.0 C, yielding a maximum predicted biodegradation of about 21%. In contrast, the models for Y2 and Y3 were statistically unreliable (P > 0.05) due to low RÂ² values. However, Y2 passed the lack-of-fit test, suggesting an adequate model form, while Y3 failed (P < 0.05), indicating an inadequate prediction model. These findings suggest future experiments should narrow factor ranges and include additional control variables to improve the predictability of Y2 and Y3. Despite these limitations, the study highlights a sustainable alternative to conventional synthetic leather, aligning with circular economy principles and supporting the United Nations Sustainable Development Goals (SDGs). Importantly, the process is resource-efficient: from 1 kg of pineapple leaves, only 20 g of fibers is obtained, and just 75 g of PALF was used in 15 experimental runs. This minimal material requirement underscores the potential of the approach for sustainable production, while highlighting potential applications in sustainable fashion, packaging, and eco-friendly product design.
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Modified 2D Viterbi Algorithm using 2D Modulation Encoding Constraints in BPMR Systems
(2020-06-01)
Sokjabok, Siwakon
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Warisarn, Chanon
;
Koonkarnkhai, Santi
;
Lee, Jaejin
The severity of inter-symbol interference (ISI) and inter-track interference (ITI) effects caused by the reduction of the spacing between bit islands in the along- and across-track directions to acquire ultra-high areal densities (ADs) is the main problem in bit-patterned magnetic recording (BPMR) systems. We call these two effects as two-dimensional (2D) interference, which can degrade the overall system performance. Practically, a one-dimensional (1D) modulation code, e.g., run-length limited (RLL) code, is essentially utilized to prevent the severe ISI effect. The use of 2D detectors is also one of the important ways to cope with the severe ITI; however, its complexity is quite high. To avoid the severe ITI effect and complex 2D detectors; therefore, we propose to apply the 1D RLL code as the 2D modulation code. Then, the 2D modulation encoding constraint is employed to reduce the number of states and branches in the trellis of the proposed modified 2D Viterbi detector. Simulation results reveal that the proposed detector not only delivers a lower complexity but also provides superior bit error rate gain, especially at ultra-high ADs and/or large location fluctuation.
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Preparation and evaluation of blend polymer films for wound dressing using vancomycin-loaded polycaprolactone and carboxymethyl cellulose via crosslinking methods: Effect of mechanical strength, antibacterial activity, and cytotoxicity
(2024-03-01)
Meedecha, Paweena
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Srisang, Naruebodee
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Eawsakul, Komgrit
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Ongtanasup, Tassanee
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Tambunlertchai, Supreeda
Polycaprolactone (PCL) and carboxymethyl cellulose (CMC) are two materials with beneficial properties for wound healing applications. Here, the simple preparation of PCL/CMC polymer films via the crosslinking method was demonstrated for the first time. The polymer films represented the suitable properties of liquid absorption and tensile strength to be used as a wound dressing. The blend polymer films can also load the vancomycin, which prolongs the drug release for effectiveness against S. aureus. The trifluoroethanol showed less toxicity in comparison with other crosslinking agents. This process can also be applied further in other medical devices and wound healing applications.
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Simple Soft-Information Developers Based on Parallel Detection Scheme in Bit-Patterned Media Recording (BPMR) Systems
(2021-06-27)
Mattayakan, Mutita
;
Sokjabok, Siwakon
;
Warisam, Chanon
Among the alternate ultra-high density data storage technologies, bit-patterned media recording (BPMR) is one of the mentioned technologies that was proposed to achieve a higher density. Due to the closeness between the magnetic islands, so the readback sequences are disrupted from the effect of two-dimensional (2D) interference, which includes both intersymbol interference (ISI) and intertrack interference (ITI). In this paper; therefore, we propose the simple and effective soft-information developers (SIDs) to improve the soft-information that are obtained from both vertical and horizontal detectors. An optimal weight was optimized under the BPMR channel before multiplying with the horizontal soft-information. The proposed SIDs and conventional 2D detector's performances were carefully compared in the terms of BER. The results show that our proposed methods achieve a gain of approximately 8 dB at a BER of 10-3.
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An improvement of BER using two-dimensional constrained code for array-reader-based magnetic recording
(2021-05-01)
Sokjabok, Siwakon
;
Koonkarnkhai, Santi
;
Lee, Jaejin
;
Warisarn, Chanon
To achieve ultra-high areal densities in future magnetic recording technologies such as bit-patterned magnetic recording (BPMR) systems, each bit-island must be closely moved. However, the reduction of bit island spacing always leads to both inter-symbol interference (ISI) and inter-track interference (ITI), which can degenerate system performance. Previously, a one-dimensional (1D) run-length limited (RLL) code was employed to efficiently avoid the ISI effect, while a two-dimensional (2D) detector is widely utilized to deal with the ITI effect as well. However, its complexity is higher than the traditional 1D detector. Therefore, to avoid the fatal data patterns that lead to severe ITI effect, we first present the application of 1D RLL code to be as the 2D modulation code in the multi-head multi-track BPMR systems. Moreover, we also present the modified 2D Viterbi detector that is designed based on our proposed encoding condition. The numbers of state and branch in the traditional trellis's structure are properly reduced according to encoding condition, thus it does not only provide a lower complexity but also operate better than the traditional 2D Viterbi detector. Results reveal that our proposed coding scheme and modified 2D Viterbi detector can efficiently protect and cope with the ITI effect.
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Constrained codes in single-reader/two-track reading bit-patterned magnetic recording
(2021-01-01)
Sokjabok, S.
;
Mattayakan, M.
;
Buajong, C.
;
Koonkarnkhai, S.
;
Kovintavewat, P.
A reduction in track width of ultra-high density magnetic recording such as bit-patterned media recording (BPMR) results in an increase in areal density. However, the unfortunate appearance of extreme inter-symbol interference (ISI) and inter-track interference (ITI) can severely deteriorate the system performance. To deal with these problems, we propose to use a single-reader/two-track reading (SRTR) technique, where a single reader was employed to read two parallel-track at once and the bit islands were arranged in a staggered manner. Then, a received readback signal was sampled at an over-sampling rate, where an obtained data sequence can be operated using only a one-dimensional equalization and detection scheme. Moreover, we also present the simple constrained coding schemes consisting of the rate-3/5 and -4/6 constrained codes, where both are properly designed for an SRTR BPMR system by avoiding all data patterns that are more susceptible to ISI and ITI effects. Simulation results show that the severe ISI and ITI effects can be mitigated through the use of our proposed coding schemes. Consequently, the proposed systems are superior to the conventional system (without our constrained codes) at a same user density of 3.0 Tb/in2.

Sokjabok, Siwakon

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