• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.504-515
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• 2008

Fast transmission speeds and various wired network services have been combined with the convenience and mobility of wireless services. The combination of wired/wireless technologies is spreading rapidly since it enables the creation of new services and provides new features to both users and service providers. In such wired/wireless integrated services, network integration is very important because such systems are integrated by a linkage between heterogeneous networks and they involve an integration of transmission technologies across networks. In this situation, existing security and communication technologies are unsuitable since the network are integrated with heterogeneous networks. The network may also have several security flaws. In existing homogeneous networks, user authentication and key management between heterogeneous networks are required for these new technologies. The establishment of security technologies for heterogeneous devices is a very important task between homogeneous networks. In this paper, we propose a secure and efficient key management system for a heterogeneous network environment. Our system provides secure communications between heterogeneous network devices.

• Genomics & Informatics
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• v.21 no.1
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• pp.7.1-7.11
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• 2023

The gram-positive bacterium Listeria monocytogenes is an important foodborne intracellular pathogen that is widespread in the environment. The functions of hypothetical proteins (HP) from various pathogenic bacteria have been successfully annotated using a variety of bioinformatics strategies. In this study, a HP Imo0888 (NP_464414.1) from the Listeria monocytogenes EGD-e strain was annotated using several bioinformatics tools. Various techniques, including CELLO, PSORTb, and SOSUIGramN, identified the candidate protein as cytoplasmic. Domain and motif analysis revealed that the target protein is a PemK/MazF-like toxin protein of the type II toxin-antitoxin system (TAS) which was consistent with BLASTp analysis. Through secondary structure analysis, we found the random coil to be the most frequent. The Alpha Fold 2 Protein Structure Prediction Database was used to determine the three-dimensional (3D) structure of the HP using the template structure of a type II TAS PemK/MazF family toxin protein (DB ID_AFDB: A0A4B9HQB9) with 99.1% sequence identity. Various quality evaluation tools, such as PROCHECK, ERRAT, Verify 3D, and QMEAN were used to validate the 3D structure. Following the YASARA energy minimization method, the target protein's 3D structure became more stable. The active site of the developed 3D structure was determined by the CASTp server. Most pathogens that harbor TAS create a crucial risk to human health. Our aim to annotate the HP Imo088 found in Listeria could offer a chance to understand bacterial pathogenicity and identify a number of potential targets for drug development.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.19-23
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• 2013

A simple and rapid method has been developed and validated for simultaneous determination of each macrolides residues (spiramycin, josamycin, tilmicosin, tylosin) in chicken muscle by high-performance liquid chromatography- photo diode array (HPLC-PDA). Chicken muscle sample have been extracted with liquid-liquid extraction process; analytes was extracted by acetonitrile, and then defatted with hexane saturated by acetonitrile. The HPLC separation was performed on a Unison UK-$C_{18}$ ($150mm{\times}3.0mm$, $3{\mu}m$) with a gradient system of 0.1% trifloroacetic acid (TFA) and 0.1% trifloroacetic acid (TFA) in acetonitrile as the mobile phase. The drugs were detected at 232 nm for spiramycin and josamycin, and 287 nm for tilmicosin and tylosin. The limits of quantification (LOQs) were between 27 and $59{\mu}g/kg$; and the intra- and inter-day precision (relative standard deviation; RSD) was between 0.9-13.2 and 2.4-13.1%, respectively in chicken muscle sample. The method may has been successfully applied for multiresidue determination of four macrolides below the maximum residue limits (MRLs) established by the European Union (EU).

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.119-119
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• 2011

This study examined the synthesis of large area graphene and the change of its characteristics depending on the ratio of CH4/H2 by using the thermal CVD methods and performed the experiments to control the electron-hole conduction and Dirac-point of graphene by using chemical doping methods. Firstly, with regard to the characteristics of the large area graphene depending on the ratio of CH4/H2, hydrophobic characteristics of the graphene changed to hydrophilic characteristics as the ratio of CH4/H2 reduces. The angle of contact also increased to 78$^{\circ}$ from 58$^{\circ}$. According to the results of Raman spectroscopy showing the degree of defect, the ratio of I(D)/I(G) increases to 0.42% from 0.25% and the surface resistance also increased to 950 ${\Omega}$ from 750 ${\Omega}$/sq. As for the graphene synthesis at the high temperature of 1,000$^{\circ}$ by using CH4/H2 in a Cu-Foil, the possibility of graphene formation was determined as a function of the ratio of H2 included in the fixed quantity of CH4 as per specifications of every equipment. It was observed that the excessive amount of H2 prevented graphene from forming, as extra H-atoms and molecules activated the reaction to C-bond of graphene. Secondly, in the experiment for the electron-hole conduction and the Dirac-point of graphene using the chemical doping method, the shift of Dirac-point and the change in the electron-hole conduction were observed for both the N-type (PEI) and the P-type (Diazonium) dopings. The ID-VG results show that, for the N-type (PEI) doped graphene, Dirac-point shifted to the left (-voltage direction) by 90V at an hour and by 130 V at 2 hours respectively, compared to the pristine graphene. Carrier mobility was also reduced by 1,600 cm2/Vs (1 hour) and 1,100 cm2/Vs (2 hours), compared to the maximum hole mobility of the pristine graphene.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.4
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• pp.259-266
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• 2015

Cervical cancer is the third most common cancer among women worldwide. Cervical cancer is significantly associated with human papillomavirus (HPV) infection. The prevalence of HPV infection is influenced by geography, immune status, sexual history and genetic factors. For example, geographically, HPV prevalence varies from 1.5% to 39%. However, little is known about the relationship between HPV prevalence and age. An analysis of HPV prevalence by age will help determine when high-risk groups are exposed to HPV. Such an analysis could also demonstrate a correlation between specific HPV genotypes and age. In addition, the analysis might clarify the optimum age for using vaccines. In this study, HPV prevalence and genotype distribution among Korean and Chinese women are analyzed by age. The REBA HPV-ID$^{(R)}$ assay (YD diagnostics, Yong-in, Republic of Korea) was used for detecting HPV genotypes in uterine cervical liquid-based cytology samples from 533 women from Korea and 324 from East China (Western Shandong province. Women with severe dysplasia such as SCC (Squamous cell carcinoma) and HSIL (High-grade squamous intraepithelial lesion) groups were primarily in their 40s and 50s, whereas women with mild and moderate dysplasia (ASCUS and LSIL groups) were primarily in their 30s and 40s. Women with HPV genotype 16 and 18 infections were primarily in their 40s. The results suggest that HPV infection is associated with certain age groups in the Korean population.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.863-870
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• 2016

We investigated the physical/chemical phenomena that a slow loss of $CO_2$ inventory into sodium after the sodium-$CO_2$ boundary failure in printed circuit heat exchangers (PCHEs), which is considered for the supercritical $CO_2$ Brayton cycle power conversion system of a sodium-cooled fast reactor (SFR). The first phenomenon is plugging inside narrow sodium channels by micro cracks and the other one is damage propagation referred to as wastage combined with the corrosion/erosion effect. Experimental results of plugging shows that sodium flow immediately stopped as $CO_2$ was injected through the nozzle at $300{\sim}400^{\circ}C$ in 3 mmID sodium channels, whereas sodium flow stopped about 60 min after $CO_2$ injection in 5 mmID sodium channels. These results imply that if pressure boundary of sodium-$CO_2$ fails a narrow sodium channel would be plugged by reaction products in a short time whereas a relatively wider sodium channel would be plugged with higher concentration of reaction products. Wastage by the erosion effect of $CO_2$ (200~250 bar) hardly occurred regardless of the kinds of materials (stainless steel 316, Inconel 600, and 9Cr-1Mo steel), temperature ($400{\sim}500^{\circ}C$), or the diameter of the $CO_2$ nozzle (0.2~0.8 mm). Velocities at the $CO_2$ nozzle were specified as Mach 0.4~0.7. Our experimental results are expected to be used for determining the design parameters of PCHEs for their safeties.

• Journal of the Korean Magnetics Society
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• v.25 no.3
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• pp.67-73
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• 2015

This is a basic research for improving soft magnetic property of Fe based nano crystalline alloy powder core. The main study is done around characteristics of permeability, core loss, and DC bias depending on amount of insulation coating agent and particle size. First, $Fe_{73.5}Si_{13.5}B_9Nb_3Cu_1$ amorphous alloy ribbon was fabricated by using the planar flow casting (PFC) device. Then, heat treatment and ball milling were done to obtain alloy powder. The amount of polyether imide (PEI) added to it was varied by 0.5, 1.0, 2.0, 2.5 wt% to have compression molding into $16ton/cm^2$. After going through crystalline heat treatment, the made toroidal nano crystalline powder core ($OD12.7mm^*ID7.62mm^*H4.75mm$) had smaller permeability as amount of insulation coating agent decreases. However, it was found out that core loss and DC bias characteristics have been improved. The reason for this results were expected to be because green density of power core decreases as amorphous alloy powder particles become smaller as amount of alloy powder insulation coating agent increases, it was determined that 1 wt% of insulation coating agent is appropriate. Also, for powder core made based on alloy powder size with amount of insulation coating agent fixed at 1 wt%, effective permeability and core loss were outstanding as particle size became bigger. However, characteristics of DC bias became worse as applied DC field increases. This is expected to be due to insulation effect, residual pores, or molding density of powder core resulting from thickness of coating on surface of alloy powder.

• Journal of Life Science
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• v.32 no.4
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• pp.310-317
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• 2022

Recently, interest in the harmful factors of particulate matter (PM), a major component of air pollution, has been increasing. In particular, PM_2.5 with a diameter of less than 2.5 ㎛ is well known to induce oxidative stress accompanied by autophagy in human lung epithelial cells. However, studies on whether PM_2.5 increases autophagy under oxidative stress and whether this process is reactive oxygen species (ROS)-dependent are insufficient. Therefore, in this study, we investigated whether PM_2.5 promotes autophagy through the generation of ROS in human alveolar epithelial A594 cells. According to our results, cells co-treated with PM_2.5 and hydrogen peroxide (H₂O₂) showed a lower cell viability than cells treated with each alone, which was associated with increased total and mitochondrial ROS production. The co-treatment of PM_2.5 and H₂O₂ also increased autophagy induction, which was confirmed through Cyto-ID staining, and the expression of autophagy biomarker proteins increased. However, when ROS generation was artificially blocked by N-acetyl-L-cysteine pretreatment, the reduction in cell viability and induction of autophagy by PM_2.5 and H₂O₂ co-treatment were markedly attenuated. Therefore, the present results suggest that PM_2.5-induced ROS generation may play a critical role in autophagy induction in A549 cells.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.269-277
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• 2003

Some species of true bugs have become serious problems in rice, upland crops, and tree fruits. It would be meaningful to understand research status by reviewing articles on those true bugs in Korea. Articles on those bugs published in several scientific Korean journals were reviewed, except articles on true bugs on rice plants; CD Part 1 included classification and morphological studies on eggs and larvae of Piesma spp., on external genitalia of Gonopsis affinis, and on spermathecae of some Podopinae and Asopinae species. $\circled2$ Development and growth analysis of Piesma sp., P. maculata, and 2 species of Coreidae were reviewed in part 2. $\circled3$ In part 3 we reviewed with major pest bug species on soybean, sweet persimmon, yuzu, citrus, chrysanthemum, and Cynanchum wilfordii, and insect fauna in mountain areas. $\circled4$ In part 4, damage levels in soybean, sweet persimmon, yuzu, grapes were reviewed. $\circled5$ ID In part 5 we reviewed seasonal occurrence patterns of Halyomorpha halys, Plautia stali, Riptortus clavatus in sweet persimmon orchards, of some species in soybean fields, of Nysius plebejus on chrysanthemum, and of Tropidothorax cruciger on Cynanchum wilfordii. $\circled6$ Chemical control methods in a sweet persimmon orchard, in grapevine yards, in a soybean field, and in a chrythansemum field were introduced in part 6. Some laboratory bioassay on insecticides against R. clavatus were mentioned, too. $\circled7$ Finally in part 7, researches on transmission by Halyomorpha halys and Cyrtopeltis tenuis of micoplasma-like organism which is a pathogen of paulownia withces' -broom to Catharanthus roseus were reviewed.

• Journal of Broadcast Engineering
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• v.14 no.4
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• pp.518-536
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• 2009

To verify the performance of a Distributed Translator Network(DTxR) system in the real world conditions, 5 legacy DTV broadcasting repeater sites were implemented with 5 DTxR systems and field-tested by the DTV field test truck. The 4 DTV broadcasting repeater sites are selected in congested areas where their service areas are overlapped and the 5th site is deviated from the other sites to examine the effect of long-delayed multipath signals. First of all, we checked the receiving signal of the main station that used as a transmitting signal in 5 DTxR systems on the pre-selected 60 test points and tested every case of a DTxR system's on & off except 1 repeater site due to the already built-in DTV repeater system. The test items are received signal electric field strength, noise margin, ease of reception and subjective evaluation of the picture quality for received signals. We used 3rd, 5th, and 6th generation DTV receivers to examine the differences of the receivability by each generation of DTV receivers. Reviewing the test results, we conclude that the DTxR system can be adopted in the current DTV Repeater sites and it could improve the quality and receivability of the main signals by extending the service areas and enhancing the signal levels in the shadow areas without using the extra broadcasting channels.