• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.257-270
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• 2021

Since African swine fever (ASF) spread to East Asia, a fatal crisis has occurred in the global pig industry, because Asia is dominant in pig production. Although some studies conducted bibliometric analysis on ASF, few studies compared research networks, and identified subthemes by major keywords. To fill this gap, this study identified the knowledge structure network of the research, its influence, and core research themes by utilizing the bibliometric analysis of 337 ASF-related journal articles over 50 years from 1970 to 2020 on the Web of Science. The result indicated that papers are mainly published in the fields of veterinary science, virology, microbiology, infectious disease and applied microbiology, and in particular, the fields of veterinary science and virology showed unrivaled weights as they account for 73.40%. With regard to cooperative relationships, European countries such as the UK, Germany, Italy, and Denmark, centered on Spain, are actively contributing to the ASF research. China, France, Thailand, Japan, Vietnam, and South Korea are leading research cooperation, centering on the United States. In the early stage of the studies, major keywords appeared to be related to outbreaks, quarantine and diagnosis, and in the middle stage, the keywords were expanded to a wide range of pig diseases. Recently, the keywords are becoming more diverse towards antibodies, cross-border transmission and disease monitoring. Based on data on major keywords related to ASF, this study proposed discussions and implications for activating ASF research including genotype, protein, vaccine, diagnosis, defense against infection and epidemiological investigation.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3317-3323
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• 2022

Half Value Layer calculations theoretically need prior specification of linear attenuation calculations, since the HVL value is derived by dividing ln(2) by the linear attenuation coefficient. The purpose of this study was to establish a direct computational model for determining HVL, a vital parameter in nuclear radiation safety studies and shielding material design. Accordingly, a typical gamma-ray transmission setup has been modeled using MCNPX (version 2.4.0) general-purpose Monte Carlo code. The MCNPX code's INPUT file was designed with two detection locations for primary and secondary gamma-rays, as well as attenuator material between those detectors. Next, Half Value Layer values of some well-known gamma-ray shielding materials such as lead and ordinary concrete have been calculated throughout a broad gamma-ray energy range. The outcomes were then compared to data from the National Institute of Standards and Technology. The Half Value Layer values obtained from MCNPX were reported to be highly compatible with the HVL values obtained from the NIST standard database. Our results indicate that the developed INPUT file may be utilized for direct computations of Half Value Layer values for nuclear safety assessments as well as medical radiation applications. In conclusion, advanced simulation methods such as the Monte Carlo code are very powerful and useful instruments that should be considered for daily radiation safety measures. The modeled MCNPX input file will be provided to the scientific community upon reasonable request.

• Journal of IKEEE
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• v.26 no.4
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• pp.659-670
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• 2022

An 830-Mb/s/pin transceiver for a controller supporting ×32 LPDDR2 memory is designed. The transmitter consists of eight unit circuits has an impedance in the range of 34Ω ∽ 240Ω, and its impedance is controlled by an impedance correction circuit. The transmitted DQS signal has a phase shifted by 90° compared to the DQ signals. In the receive operation, the read time calibration is performed by per-pin skew calibration and clock-domain crossing within a byte. The implemented transceiver for the LPDDR2 memory controller is designed by using a 55-nm process using a 1.2V supply voltage and has a maximum signal transmission rate of 830 Mb/s/pin. The area and power consumption of each lane are 0.664 mm² and 22.3 mW, respectively.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1062-1070
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• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• Journal of the Korea Society of Computer and Information
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• v.27 no.12
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• pp.231-238
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• 2022

In this paper, among short-range wireless communication technologies such as Beacon, Bluetooth, UWB (Ultra-wideband), ZigBee, NFC (Near Field Communication), Z-Wave, 6LoWPAN (IPv6 over Low power WPAN), D2D (Device to Device), etc., proposed an IoT service platform based on a beacon that can provide indoor positioning. And, a beacon-linked web server was designed by blocking indiscriminate beacon spam signals and applying REST web service technology with flexibility and scalability. Data accessibility between different devices was verified by testing the success rate of data transmission, the success rate of blocking beacon push, the success rate of IoT interlocking processing, the accuracy of location positioning, and the success rate of REST web service-based data processing. Through the designed IoT service platform, various proposals and research on short-distance-based business models and service platforms will be conducted in the future.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.153-163
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• 2023

This study is situated in the context of intelligent transport systems, where in-vehicle devices assist drivers to avoid accidents and therefore improve road safety. The vehicles present in a given area form an ad' hoc network of vehicles called vehicular ad' hoc network. In this type of network, the nodes are mobile vehicles and the messages exchanged are messages to warn about obstacles that may hinder the correct driving. Node mobilities make it impossible for inter-node communication to be end-to-end. Recognizing this characteristic has led to delay-tolerant vehicular networks. Embedded devices have small buffers (memory) to hold messages that a node needs to transmit when no other node is within its visibility range for transmission. The performance of a vehicular delay-tolerant network is closely tied to the successful management of the nodes' transit buffer. In this paper, we propose a message transit buffer management model for nodes in vehicular delay tolerant networks. This model consists in setting up, on the one hand, a policy of dropping messages from the buffer when the buffer is full and must receive a new message. This drop policy is based on the concept of intermediate node to destination, queues and priority class of service. It is also based on the properties of the message (size, weight, number of hops, number of replications, remaining time-to-live, etc.). On the other hand, the model defines the policy for selecting the message to be transmitted. The proposed model was evaluated with the ONE opportunistic network simulator based on a 4000m x 4000m area of downtown Bouaké in Côte d'Ivoire. The map data were imported using the Open Street Map tool. The results obtained show that our model improves the delivery ratio of security alert messages, reduces their delivery delay and network overload compared to the existing model. This improvement in communication within a network of vehicles can contribute to the improvement of road safety.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.287-295
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• 2023

Iron nanoparticles (Fe-NPs) were synthesized employing Lagenaria siceraria (LS) leaf aqueous extract as a reducing and capping medium to remove methylene blue (MB) dye and have antibacterial properties against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus). The formation of LS-Fe-NPs (Lagenaria-siceraria-iron-nanoparticles) was confirmed by a change in color from pale yellow to dark brown. Characterization techniques, such as particle size analysis (PSA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), were employed to prove nano spherical particles of size range between 80-100 nm. Phytochemicals and the presence of iron in LS-Fe-NPs nanoparticles were proved by UV-visible spectrophotometry. Further, Fourier transform infrared spectroscopy (FTIR) analysis results confirmed the existence of bioactive molecules in the plants. The magnetic property was analyzed using a vibrating sample magnetometer (VSM), which displayed that the synthesized nanoparticles were superparamagnetic and exhibiting a saturation magnetization of 12.5 emu/g. Synthesized magnetic nanoparticles were used in methylene blue (MB) dye removal through adsorption. About 83% of 100 mg/L MB dye was removed within 120 min at pH 6 with a maximum adsorption capacity of 246.8 mg/g. Antibacterial efficacy of LS-Fe-NPs was screened against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus), respectively, and found that LS-Fe-NPs were effective against Staphylococcus aureus.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.45-55
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• 2006

This paper presents the results of full-scale uplift load tests performed on 30 passive anchors grouted to various lengths at Taean site in Korea. Various rock types were tested, ranging from highly weathered to sound gneiss. Rock anchors were installed over a wide range of rock types and qualities with a fixed anchored depth of $1{\sim}4m$. The majority of installations used SD4O-D51 no high grade steel rebar to induce rock failure prior to rod failure. In many tests, rock failure was reached and the ultimate loads were recorded along with observations of the shape and extent of the failure surface. The test results, the failure mechanisms as well as uplift capacities of rock anchors depend mostly on rock type and quality, embedded fixed length, and the strength of rebar. Based on test results, the main parameters governing the uplift capacity of the rock anchor system were determined.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.5-15
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• 2009

This paper presents the results of full-scale uplift load tests performed on 24 passive anchors grouted to various lengths at Okchun and Changnyong site. Rock anchors were installed over a wide range of rock types and qualities with a fixed anchored depth of 1~6 m. The majority of installations used D51 mm high grade steel rebar to induce rock failure prior to rod failure. However, a few installations included the use of D32 mm rebar at relatively deeper anchored depth so as to induce rod failure. In many tests, rock failure was reached and the ultimate loads were recorded along with observations of the shape and extent of the failure surface. In addition to field tests, laboratory pullout tests were conducted to determine bond strength and bond stress-shear slip relation at the tendon/grout interface when a corrosion protection sheath is installed in the cement-based grout. The test results show that the ultimate tendon-grout bond strength is measured from 18~25% of unconfined compressive strength of grout. One of the important results from these tests is that the measured strains along the corrosion protection sheath were so small that practically the reduction of bond strength by the presence of sheath would be negligible.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.197-202
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• 2023

Calcium fluoride (CaF₂) single crystal is applied to numerous industrial applications, especially for optical uses. To have excellent optical transmission properties, however, CaF₂ crystals should be carefully fabricated through liquid-phase crystal growth techniques. In this study, as one of the early stage research activities to grow CaF₂ crystals with a good transmittance at the ultraviolet wavelength range, computational thermodynamic models were provided to deepen the understanding of the crystal growing processes of CaF₂ under various conditions. To remove point defects and oxygen impurities in the grown CaF₂ crystals, the system was thermodynamically evaluated to get optimal process conditions. From the reviews of previous experimental studies, computational thermodynamic approaches were found to be an effective and powerful tool to understand the meaning of the crystal growth processes and to obtain optimal process conditions.