• Advances in nano research
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• v.15 no.1
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• pp.35-48
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• 2023

Nanoparticles are known for their outstanding properties such as particle size, surface area, optical and electrical properties. These properties have significantly boasted their applications in various surface phenomena. In this work, calcium oxide nanoparticles were synthesized from periwinkle shells as an approach towards waste management through resource recovery. The sol gel method was used for the synthesis. The nanoparticles were characterized using X-Ray diffractometer (XRD), Fourier Transformed Infra-Red Spectrophotometer (FTIR), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultra violet visible spectrophotometer (UV-visible). While DLS and SEM underestimate the particle diameter, the BET analysis reveals surface area of 138.998 m²/g, pore volume = 0.167 m³/g and pore diameter of 2.47 nm. The nanoparticles were also employed as an adsorbent for the purification of dye (methyl orange) contaminated water. The adsorbent showed excellent removal efficiency (up to 97 %) for the dye through the mechanism of physical adsorption. The adsorption of the dye fitted the Langmuir and Temkin models. Analysis of FTIR spectrum after adsorption complemented with computational chemistry modelling to reveal the imine nitrogen group as the site for the adsorption of the dye unto the nanomaterials. The synthesized nanomaterials have an average particle size of 24 nm, showed a unique XRD peak and is thermally and mechanically stable within the investigated temperature range (30 to 70 ℃).

• Advances in nano research
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• v.13 no.4
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• pp.325-339
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• 2022

Endophytes ascertain a symbiotic relationship with plants as promoters of growth, defense mechanism etc. This study is a first report to screen the endophytic population in Waltheria indica, a tropical medicinal plant. 5 bacterial and 3 fungal strains in leaves, 3 bacterial and 1 yeast species in stems were differentiated morphologically and identified by biochemical and molecular methods. The phylogenetic tree of the isolated endophytes was constructed using MEGA X. Silver nanoparticles were biosynthesized from a rare endophytic bacterium Cupriavidus metallidurans isolated from the leaf of W. indica. The formation of silver nanoparticles was confirmed by UV-Visible spectrophotometer that evidenced a strong absorption band at 408.5 nm of UV-Visible range with crystalline nature and average particle size of 16.4 nm by Particle size analyzer. The Fourier Transform Infra-Red spectrum displayed the presence of various functional groups that stabilized the nanoparticles. X-ray diffraction peaks were conferred to face centered cubic structure. Transmission Electron Microscope and Scanning Electron Microscope revealed the spherical-shaped, polycrystalline nature with the presence of elemental silver analyzed by Energy Dispersive of X-Ray spectrum. Selected area electron diffraction also confirmed the orientation of AgNPs at 111, 200, 220, 311 planes similar to X-ray diffraction analysis. The synthesized nanoparticles are evaluated for antimicrobial activity against 7 bacterial and 3 fungal pathogens. A good zone of inhibition was observed against pathogenic bacteria than fungal pathogens. Thus the study could hold a key aspect in drug discovery research and other pharmacological conducts of human clinical conditions.

• Advances in nano research
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• v.15 no.4
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• pp.295-304
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• 2023

In this paper, a powerful photocatalyst based on carbon nanocomposite is developed in order to obtain a new material applicable in water treatment and especially for the discoloration of effluents used in the textile industry. For that, TiO₂-graphene nanocomposites have been successfully synthesized by a mixture of Functionalized Graphene Sheet (FGS) and tetrachlorotitanium complexes to form FGS-TiO₂ nanocomposite. In the presence of an anionic surfactant, we used a new chemical process to functionalize graphene sheets in order to make them an excellent medium for blocking and preventing the aggregation of TiO₂ nanoparticles. The components of these nanocomposites are characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), which confirms the successful formation of the FGS-TiO₂ nanocomposite. It was found that the TiO₂ nanoparticles were dispersed uniformly on the graphene plane which possesses better charge separation capability than pure TiO₂. The FGS-TiO₂ nanocomposites exhibited higher photocatalytic activity compared to pure TiO₂ for the removal of three dyes: such as Methylene Blue (MB), Bromophenol Blue (BB) and Alizarin Red-S (AR) in water. The removal process was fast and more efficient with FGS-TiO₂ nanocomposite in daylight (in the absence of UV irradiation) compared to pure TiO₂ nanoparticles without and under UV in all pH range.

• Journal of the Korea Society of Computer and Information
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• v.28 no.11
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• pp.103-111
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• 2023

Recently, many universities have used various electronic attendance systems such as NFC, QR code, Sound-QR, Bluetooth BLE authentication, and face recognition to process attendance. However, existing methods have various problems such as attendance errors due to deformation of authentication signals, mis-recognition attendance from outside the classroom, and difficulty to process seat absence during class. Therefore, this study proposes a high-frequency signal-based electronic attendance system to solve these problems and manage more accurate electronic attendance. As the high-frequency signal replaces the BLE signal, and the transmission range of the signal is limited to the classroom, and the signal value can be immediately changed if a change of the signal is needed. To verify the performance of the proposed system, we conducted a comparative experiment with the Bluetooth based electronic attendance system, and as a result, the proposed method showed high accuracy. Thus, the proposed method will be a useful service that can be immediately used in smart device-based electronic attendance system.

• Mycobiology
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• v.51 no.4
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• pp.195-209
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• 2023

The seed borne disease such as bakanae is difficult to control. Crop yield loss caused by bakanae depending on the regions and varieties grown, ranging from 3.0% to 95.4%. Bakanae is an important disease of rice worldwide and the pathogen was identified as Fusarium fujikuroi Nirenberg (teleomorph: Gibberella fujikuroi Sawada). Currently, four Fusaria (F. fujikuroi, F. proliferatum, F. verticillioides and F. andiyazi) belonging to F. fujikuroi species complex are generally known as the pathogens of bakanae. The infection occurs through both seed and soil-borne transmission. When infection occurs during the heading stage, rice seeds become contaminated. Molecular detection of pathogens of bakanae is important because identification based on morphological and biological characters could lead to incorrect species designation and time-consuming. Seed disinfection has been studied for a long time in Korea for the management of the bakanae disease of rice. As seed disinfectants have been studied to control bakanae, resistance studies to chemicals have been also conducted. Presently biological control and resistant varieties are not widely used. The detection of this pathogen is critical for seed certification and for preventing field infections. In South Korea, bakanae is designated as a regulated pathogen. To provide highly qualified rice seeds to farms, Korea Seed & Variety Service (KSVS) has been producing and distributing certified rice seeds for producing healthy rice in fields. Therefore, the objective of the study is to summarize the recent progress in molecular identification, fungicide resistance, and the management strategy of bakanae.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.487-495
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• 2022

This paper describes the design and development of a high-power transmit receive module(TRM) for mounting on X-band synthetic aperture radar(SAR) of the NEXTSat-2. The TRM generates a high-power pulse signal with a bandwidth of 100 MHz in the target frequency range of X-band and amplifies a low-noise on the received signal. Tx. path of the TRM has output signal level of more than 200 watts (53.01 dB), pulse droop of 0.35 dB, signal strength change of 0.04 dB during transmission signal output, and phase change of 1.7 ˚. Rx. path has noise figure of 3.99 dB and gain of 37.38 ~ 37.46 dB. It was confirmed the TRM satisfies all requirements. The TRM mounted on the NEXTSat-2 flight model(FM) which will be launched using the KSLV-II (Nuri).

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.216-221
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• 2024

Ion cyclotron range of frequency (ICRF) heating system is an important auxiliary heating method in the experimental Advanced Superconducting Tokamak (EAST). In EAST, several megawatts of power are transmitted with coaxial transmission lines and coupled to the plasma. For the long pulse and high power operation of the ICRF waves heating system, it is very important to effectively control the power and initial phase of the ICRF signals. In this paper, a power and phase feedback control system is described based on field programmable gate array (FPGA) devices, which can realize complicated algorithms with the advantages of fast running and high reliability. The transmitted power and antenna phase are measured by a power and phase detector and digitized. The power and phase feedback control algorithms is designed to achieve the target power and antenna phase. The power feedback control system was tested on a dummy load and during plasma experiments. Test results confirm that the feedback control system can precisely control ICRF power and antenna phase and is robust during plasma variations.

• Journal of the Korea Society of Computer and Information
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• v.29 no.5
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• pp.67-74
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• 2024

As the number of coffee shops increases, many people are studying or working at coffee shops. Coffee shop operators have been required to analyze customer visits due to customer turnover and profit problems. Methods such as image analysis, QR code authentication, and Bluetooth beacon have been proposed for these statistics and analysis. However, it is difficult to use due to problems such as invasion of privacy and low accuracy. Therefore, in this study, to solve these problem and provide more accurate in-store congestion information, we propose a crowding measurement method of coffee shop using high frequency signal. There is an advantage in that a high frequency signal replaces the Bluetooth signal, and the transmission range of the signal is limited to the store, thereby increasing the accuracy of the method. To verify the performance of the proposed system, we conducted a comparative experiment with a Bluetooth based system, and as a result, the proposed method showed lower misrecognition rate. Thus, the proposed method will be an effective useful service for providing information on crowding at coffee shops and processing statistics.

• Safety and Health at Work
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• v.14 no.4
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• pp.347-357
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• 2023

Introduction: The COVID-19 pandemic turned biological hazards in the working environment into a global concern. This systematized review of published reviews aimed to provide a comprehensive overview of the specific jobs and categories of workers exposed to biological hazards with the related prevention. Methods: We extracted reviews published in English and French in PubMed, Embase, and Web of Science. Two authors, working independently, subsequently screened the potentially relevant titles and abstracts recovered (step 1) and then examined relevant full texts (step 2). Disagreements were resolved by consensus. We built tables summarizing populations of exposed workers, types of hazards, types of outcomes (types of health issues, means of prevention), and routes of transmission. Results: Of 1426 studies initially identified, 79 studies by authors from every continent were selected, mostly published after 2010 (n = 63, 79.7%). About half of the reviews dealt with infectious hazards alone (n = 38, 48.1%). The industrial sectors identified involved healthcare alone (n = 16), laboratories (n = 10), agriculture (including the animal, vegetable, and grain sectors, n = 32), waste (n = 10), in addition of 11 studies without specific sectors. The results also highlighted a range of hazards (infectious and noninfectious agents, endotoxins, bioaerosols, organic dust, and emerging agents). Conclusion: This systematized overview allowed to list the populations of workers exposed to biological hazards and underlined how prevention measures in the healthcare and laboratory sectors were usually well defined and controlled, although this was not the case in the agriculture and waste sectors. Further studies are necessary to quantify these risks and implement prevention measures that can be applied in every country.

• International Journal of Computer Science & Network Security
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• v.24 no.9
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• pp.127-134
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• 2024

The acute respiratory infection known as a coronavirus (COVID-19) may present with a wide range of clinical manifestations, ranging from no symptoms at all to severe pneumonia and even death. Expert medical systems, particularly those used in the diagnostic and monitoring phases of treatment, have the potential to provide beneficial results in the fight against COVID-19. The significance of healthcare mobile technologies, as well as the advantages they provide, are quickly growing, particularly when such applications are linked to the internet of things. This research work presents a knowledge-based smart system for the primary diagnosis of COVID-19. The system uses symptoms that manifest in the patient to make an educated guess about the severity of the COVID-19 infection. The proposed inference system can assist individuals in self-diagnosing their conditions and can also assist medical professionals in identifying the ailment. The system is designed to be user-friendly and easy to use, with the goal of increasing the speed and accuracy of COVID-19 diagnosis. With the current global pandemic, early identification of COVID-19 is essential to regulate and break the cycle of transmission of the disease. The results of this research demonstrate the feasibility and effectiveness of using a knowledge-based smart system for COVID-19 diagnosis, and the system has the potential to improve the overall response to the COVID-19 pandemic. In conclusion, these sorts of knowledge-based smart technologies have the potential to be useful in preventing the deaths caused by the COVID-19 pandemic.