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Lifespan Estimation of Closed-Circuit Television (CCTV) Systems Using Weibull Modeling
(2026-02-01)
Chutchavong, Vanvisa
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Pirajnanchai, Virote
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Doungpan, Satawat
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Kasettakarn, Witchapon
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Phungtua-eng, Thanapol
Ensuring the availability and reliability of electronic components or materials during operation necessitates conducting a sampling inspection of their lifespan. This is particularly crucial when comparing equipment or materials deployed in various areas with diverse environments, conditions, and situations. Many studies rely on one-method parameter estimation methods, which fall short in identifying the two explicit parameters of the Weibull distribution. Moreover, inaccurate parameter estimation methods impede the attainment of reliable analysis results. Consequently, this paper introduces three analytical estimation methods to determine the parameters of the Weibull distribution. The accuracy of these methods is evaluated using the mean square error (MSE). Furthermore, we utlized the Kolmogorov–Smirnov and Anderson–Darling test on real datasets, confirming that the data follow a Weibull distribution. Simulation results indicate that the maximum likelihood estimate outperforms the other estimators by minimizing the MSE and yielding optimal parameters. These optimal parameters were then applied to real CCTV datasets, demonstrating a good fit and enabling assessment of CCTV lifespan through the mean time to failure, which is estimated to be 6.6 years. This holds true even when the equipment operates in environments with different conditions and situations.
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A Flexible and Compact UWB MIMO Antenna with Dual-Band-Notched Double U-Shaped Slot on Mylar® Polyester Film
(2025-09-01)
Chutchavong, Vanvisa
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Chanwattanapong, Wanchalerm
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Wongsin, Norakamon
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Rakluea, Paitoon
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Tangjitjetsada, Maleeya
Ultra-wideband (UWB) technology is a crucial facilitator for high-data-rate wireless communication due to its extensive frequency spectrum and low power consumption. Simultaneously, multiple-input multiple-output (MIMO) systems have garnered considerable attention owing to their capability to enhance channel capacity and link dependability. This article discusses the development of small, high-performance MIMO UWB antennas with mutual suppression capabilities to fully use the benefits of both technologies. Additionally, the suggested antenna features a straightforward design and dual-band-notched characteristics. The antenna structure includes two radiating elements measuring 85 × 45 mm2. These elements use a rectangular patch provided by a coplanar waveguide (CPW). Double U-shaped slots are incorporated into the rectangular patch to introduce dual-band-notched properties, which help mitigate interference from WiMAX and WLAN communication systems. The antenna is fabricated on a Mylar® polyester film substrate of 0.3 mm in thickness, with a dielectric constant of 3.2. According to the measurement results, the suggested antenna functions efficiently across the frequency spectrum of 2.29 to 20 GHz, with excellent impedance matching throughout the bandwidth. Furthermore, it provides dual-band-notched coverage at 3.08–3.8 GHz for WiMAX and 4.98–5.89 GHz for WLAN. The antenna exhibits impressive performance, including favorable radiation attributes, consistent gain, and little mutual coupling (less than −20 dB). Additionally, the envelope correlation coefficient (ECC) is extremely low (ECC < 0.01) across the working bandwidth, which indicates excellent UWB MIMO performance. This paper offers an appropriate design methodology for future flexible and compact UWB MIMO systems that can serve as interference-resilient antennas for next-generation wireless applications.
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Synthesis of Video Gain Equalizer via Distributed circuits
(2025-01-01)
Chutchavong, Vanvisa
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Pirajnanchai, Virote
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Rattanathanawan, Pongpan
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Ngammongkolwong, Sudasawan
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Puntapa, Vorawut
This paper presents a linear luminance and chrominance gain equalizer in video waveform transmission. Practically, the distributed devices have physical characteristics similar to the transmission line. Therefore, it can be employed to function in approximately as a passive lumped element. For this purpose, a novel transformation can be realized on equalizer using commemorated passive and active filters with uniformly distributed URC lines. In this paper we introduce two types of gain equalizers. The first type consists of resistive, conductive and capacitive, known as uniform GCR elements. The second type approximated by the uniformly distributed RC transfer function. As the results the proposed gain equalizer prove in equalizing both the luminance and chrominance gain distortions correction. From the simulation results, it is shown that the proposed distributed circuit gives good amplitude chrominance characteristic for both types of luminance gain equalizers.
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A Wideband Antenna Integrated into a Military Fabric for X-Band Satellite Communication
(2025-01-01)
Chutchavong, Vanvisa
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Aroonmitr, Pongsathorn
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Rakluea, Paitoon
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Jangjing, Thinnawat
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Rakluea, Chawalit
The study examines a wideband antenna solution that combines military fabric integration with X-band satellite functionality. The proposed antenna, with dimensions of 40×40×0.565 mm3, is constructed using gabardine fabric with a herringbone twill (HBT) pattern with physical parameters of 0.395 mm thickness, relative permittivity of 1.8848, and dielectric loss tangent measuring 0.02611. Testing in an anechoic chamber shows excellent agreement between simulated and measured results, with the antenna operating from 7.25 - 12.28 GHz, corresponding to a fractional bandwidth of 50.89%, a measured peak gain of 6.49 dBi, while radiation patterns, return loss, and gain measurements validate its practical performance. Exploiting advancements in wearable electromagnetic systems and demonstrating seamless integration into military apparel, the proposed antenna establishes a robust solution viable for deployment in sophisticated defense communication infrastructures.
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Study on Damage to Flexible Pavement Road in Thailand: Identification Types of Crack on Roads Using Image Processing Takes
(2025-01-01)
Chutchavong, Vanvisa
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Doungpan, Satawat
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Kasettakarn, Witchapon
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Thiabkhuang, Surapit
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Phungtua-Eng, Thanapol
The detection and identification of flexible pavement road cracks pose a significant challenge for civil engineers when they start work at the beginning level, as it requires extensive work experience of engineers in classifying types of cracks for planning road maintenance. Inaccurate analysis and identification of cracks can negatively affect the quality of maintenance work and threaten the safety of road users in the future. This paper presents a case study of 60 asphalt roads managed by the Provincial Administrative Organization (PAO) in central of Thailand (case of two provinces, Uthai Thani and Nakhon Sawan), focusing on identification type road cracks. The study aims to address issues related to data preparation and classification across various domains Our data are fed model, which is photography to medium-resolution images of flexible pavement road cracks so that guidelines for engineers' inspection and identification of road cracks. We propose the development of a U-Net model specifically designed for image processing tasks. The results indicate that the U-Net model is effective in converting road cracks images into segmentation masks, and this effectiveness is evaluated using four well-defined key performance indicators.
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Assessment of Electromagnetic Field Exposure from Multiple Sources Simultaneously in the High-Frequency Range Based on Safety Standards
(2025-01-01)
Chutchavong, Vanvisa
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Aroonmitr, Pongsathorn
This study presents a method for evaluating electromagnetic field (EMF) exposure from multiple sources operating simultaneously across a wide range of frequencies, based on the guidelines defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in its 2020 publication. The proposed approach adopts the normalized exposure ratio, which combines the exposure values from all relevant sources and frequency bands. A key issue addressed in this study is the lack of standardized measurement methods for absorbed power density (S<inf>ab</inf>) in high-frequency bands above 10 GHz, despite the existence of defined exposure limits. A comparison reveals that the difference between the limits for S<inf>ab</inf> and incident power density (S<inf>inc</inf>) for the general public is relatively small when compared to the gap between the general public and occupational exposure limits. Therefore, the use of S<inf>inc</inf> is proposed as a temporary surrogate for S<inf>ab</inf> in frequency ranges where direct measurement is not yet feasible. This approach enables comprehensive exposure assessment from multiple sources under both near-field and far-field conditions. It also serves as a practical alternative while S<inf>ab</inf> measurement techniques for high-frequency applications such as 5G, WiGig, and next-generation wireless technologies are still under development.
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Improvement of Renz's Active Band-Pass Filter Using Uniformly Distributed RC Circuit
(2024-01-01)
Wachirarattanapornkul, Sorapong
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Chutchavong, Vanvisa
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Attavunich, Pornsak
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Rattanathanawan, Pongpan
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Ngammongkolwong, Sudasawan
This paper presents the improvement of Renz' s active band-pass filter. We proposed two types of band-pass filter. The first type of filter circuit structure, resembles to Renz's band-pass filter. The circuit comprising a single gain amplifier and three uniformly distributed RC network (URC). The second type band-pass filter circuit configuration consists of a gain amplifier with one URC and a double capacitive layer (DURC). From the experimental results, it is showed that the behavior of the proposed band-pass filter gives good narrow bandwidth, high Q and low sensitivities compared to the Renz's filter.
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Design of Luminance-Chrominance Gain Equalizer Using Uniformly Distributed RC Circuits
(2024-01-01)
Chutchavong, Vanvisa
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Pirajnanchai, Virote
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Doungpan, Satawat
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Ngammongkolwong, Sudasawan
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Rattanathanawan, Pongpan
The propose of this paper is to design the luminance-chrominance gain equalizer use in the video waveform transmission. As it is known, the conventional measurement and gain corrector of chrominance distortion equipment is not so simple. This network corrector has to use fillers and delay time to separate the luminance signal and chrominance signal by means of low-pass and high-pass filter in connection. Here in, we deploy the uniformly distributed RC circuit (URC). We introduce two types of equalizers. The first type is to correct the luminance signal without deteriorating the chrominance signal. The second type is designed to correct the chrominance signal with no effect to luminance signal. Both equalizers comprise of a few gain amplifiers and URC circuits. From the simulation results, it is shown that the frequency response of gain equalizer given good effective in correcting video signal distortion. We also introduce the modulated sine-squared pulse test signal for measuring and correcting the amount of low gain and high gain of the chrominance signal.
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Synthesis of Crossover Network Using O′Shea′s Transformation via URC
(2024-01-01)
Janchitrapongvej, Kanok
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Chutchavong, Vanvisa
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Doungpan, Satawat
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Ngammongkolwong, Sudasawan
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Rattanathanawan, Pongpan
This paper describes method of synthesis two-way cross-over network, namely low-pass filter and high-pass filter. Firstly, we introduce synthesis method of obtain all-pass filter. We introduce O′Shea′s transformation P(s) = cosh√SRC and Wyndrum′s transformation W(s) = tanh√SRC via uniformly distributed RC (URC) network. After obtaining a desired all-pass filter, as an elementary process. We construct low-pass filter and high-pass filter by means of all-pass filter basis. Simulation results MATLAB are carried out and stability are also investigated.
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Optimized Gaussian Pulse Design for UWB System Using Particle Swarm Optimization Based-on Generalized Bessel Polynomials
(2022-01-01)
Chutchavong, Vanvisa
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Anuwongpinit, Thanavit
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Purahong, Boonchana
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Archevapanich, Tuanjai
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Janchitrapongvej, Kanok
The ultrawideband system operates a very short pulse with enormous bandwidth to provide high data rates for data transmission. To design the UWB pulse, considering the pulse shape is very necessary, and a spectral emission mask of the designed pulse should meet the FCC spectral mask requirement between frequency range 3.1 GHz to 10.6 GHz. The traditional UWB pulse design is based on the Gaussian derivative. However, the frequency spectrum is not satisfied the FCC spectral mask requirement. In this study, the Gaussian pulse can be designed from the mathematical characteristic of the generalized Bessel polynomial. The spectral efficiency of the proposed pulse can be improved by the combination of the derivative of Gaussian pulse with a weight coefficient optimization with particle swarm optimization (PSO). PSO is a population-based optimization algorithm inspired by animal behavior. PSO is applied with generalized Bessel polynomial transfer function to gain the best weight coefficient, we proposed to optimize its weight vector to design a pulse that exceeds to FCC spectral mask. The results were found in MATLAB software show that generalized Bessel polynomials can approximate the proposed pulse with combination method and PSO. The spectral efficiency is improved to 89.30% and the spectrum is greater close to the FCC spectral mask requirement. To confirm an improved spectral efficiency compared to the previous works.

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