• Journal of the Society of Naval Architects of Korea
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• v.56 no.4
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• pp.335-342
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• 2019

The objective of this study is to analyze the mechanical properties of plywood used as a thermal insulating material for LNG CCS (Liquefied Natural Gas, Cargo Containment System). It is created by bonding an odd number of parallel and perpendicular direction for preventing contraction and expansion of wood. Also plywood is widely used as LNG CCS insulating material because of its durability, light weight and high stiffness. Since LNG CCS is loaded with liquid cargo, the impact load by sloshing during operation and the wide temperature range (room temperature, low temperature, cryogenic temperature) exposed during loading, unloading should be considered. The thickness of the plywood which is used for the membrane type MARKIII was selected as the thickness of the test specimen. In this present study, plywood is analyzed by the fracture behavior and mechanical properties of plywood by temperature and grain direction. In addition, it is necessary to analyze the fracture shape and predict the fracture strain by using regression model because the critical load may cause cracks inside the tank, which may affect the leakage of cryogenic liquid.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.357-366
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• 2019

We first confirmed the involvement of MalQ (4-${\alpha}$-glucanotransferase) in Escherichia coli glycogen breakdown by both in vitro and in vivo assays. In vivo tests of the knock-out mutant, ${\Delta}malQ$, showed that glycogen slowly decreased after the stationary phase compared to the wild-type strain, indicating the involvement of MalQ in glycogen degradation. In vitro assays incubated glycogen-mimic substrate, branched cyclodextrin (maltotetraosyl-${\beta}$-CD: G4-${\beta}$-CD) and glycogen phosphorylase (GlgP)-limit dextrin with a set of variable combinations of E. coli enzymes, including GlgX (debranching enzyme), MalP (maltodextrin phosphorylase), GlgP and MalQ. In the absence of GlgP, the reaction of MalP, GlgX and MalQ on substrates produced glucose-1-P (glc-1-P) 3-fold faster than without MalQ. The results revealed that MalQ led to disproportionate G4 released from GlgP-limit dextrin to another acceptor, G4, which is phosphorylated by MalP. In contrast, in the absence of MalP, the reaction of GlgX, GlgP and MalQ resulted in a 1.6-fold increased production of glc-1-P than without MalQ. The result indicated that the G4-branch chains of GlgP-limit dextrin are released by GlgX hydrolysis, and then MalQ transfers the resultant G4 either to another branch chain or another G4 that can immediately be phosphorylated into glc-1-P by GlgP. Thus, we propose a model of two possible MalQ-involved pathways in glycogen degradation. The operon structure of MalP-defecting enterobacteria strongly supports the involvement of MalQ and GlgP as alternative pathways in glycogen degradation.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.417-426
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• 2018

Piezoelectric shunt is an electric type damper capable of reducing the vibration of the structure. Vibration generated at the natural frequency of the structure are converted into electrical energy through the piezoelectric material attached to the structure. Electric energy can be dissipated by thermal energy using piezoelectric shunt composed of inductor and resistance to reduce vibration. In this paper, the equation for the optimum inductance required to reduce the vibration of the cantilever beam was examined and the vibration of the aluminum cantilever was reduced by using finite element analysis and experiments. In the finite element analysis, the mode shape and the strain energy distribution were calculated to examine the mounting position, and the vibration reduction of the cantilever was calculated by adjusting the inductance and resistance circuit values. In addition, in the experiment, a variable inductor module was used to reduce the vibration occurring at a specific frequency of the cantilever. Finally, based on the results of the finite element analysis and the experiment, it was verified that the piezoelectric shunt can effectively reduce the vibration of the cantilever.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1109-1114
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• 2021

Chlamydia pneumoniae is a type of pathogenic gram-negative bacteria that causes various respiratory tract infections including asthma. Chlamydia species infect humans and cause respiratory infection by rupturing the lining of the respiratory which includes the throat, lungs and windpipe. Meanwhile, the function of interleukin-4 (IL-4) in Ch. pneumoniae respiratory infection and its association with the development of airway hyperresponsiveness (AHR) in adulthood and causing allergic airway disease (AAD) are not understood properly. We therefore investigated the role of IL-4 in respiratory infection and allergy caused by early life Chlamydia infection. In this study, Ch. pneumonia strain was propagated and cultured in HEp-2 cells according to standard protocol and infant C57BL/6 mice around 3-4 weeks old were infected to study the role of IL-4 in respiratory infection and allergy caused by early life Chlamydia infection. We observed that IL-4 is linked with Chlamydia respiratory infection and its absence lowers respiratory infection. IL-4R α2 is also responsible for controlling the IL-4 signaling pathway and averts the progression of infection and inflammation. Furthermore, the IL-4 signaling pathway also influences infection-induced AHR and aids in increasing AAD severity. STAT6 also promotes respiratory infection caused by Ch. pneumoniae and further enhanced its downstream process. Our study concluded that IL-4 is a potential target for preventing infection-induced AHR and severe asthma.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.375-385
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• 2020

The purpose of this study was to investigate the quality characteristics of kimchi prepared with a single starter culture of biogenic amines (BA)-forming lactic acid bacteria (LAB) or a combined starter cultures composed of BA-forming and BA-degrading LAB. As the fermentation proceeded, the lactic acid bacterial count, titratable acidity, and BA content in kimchi prepared with myeolchi-aekjeot were slightly higher than those of kimchi prepared with saeu-jeot. The amount and type of BA produced by LAB were mostly strain dependent rather than species specific. Among all of the isolated LAB strains, the highest levels of cadaverine, histamine, putrescine and tyramine were produced by Leuconostoc mesenteroides MBK32, Lactobacillus brevis MBK34, Lactobacillus curvatus MBK31 and Enterococcus faecalis SBK31, respectively. BA-forming and BA-degrading starter cultures played an important role in the growth rate and organic acid-producing ability of LAB in kimchi. Interestingly, BA contents in kimchi increased by adding single BA-forming LAB starter were effectively lowered by the mixed cultures with BA-degrading LAB.

• Korean Journal of Veterinary Research
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• v.61 no.2
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• pp.13.1-13.8
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• 2021

Mammalian reovirus (MRV) causes respiratory and intestinal disease in mammals. Although MRV isolates have been reported to circulate in several animals, there are no reports on Korean MRV isolates from wildlife. We investigated the biological and molecular characteristics of Korean MRV isolates based on the nucleotide sequence of the segment 1 gene. In total, 144 swabs from wild animals were prepared for virus isolation. Based on virus isolation with specific cytopathic effects, indirect fluorescence assays, electron microscopy, and reverse transcription-polymerase chain reaction, only one isolate was confirmed to be MRV from a Korean roe deer (Capreolus pygargus). The isolate exhibited a hemagglutination activity level of 16 units with pig erythrocytes and had a maximum viral titer of 10^5.7 50% tissue culture infectious dose (TCID₅₀)/mL in Vero cells at 5 days after inoculation. The nucleotide and amino-acid sequences of the partial segment S1 of the MReo2045 isolate were determined and compared with those of other MRV strains. The MReo2045 isolate had nucleotide sequences similar to MRV-3 and was most similar (96.1%) to the T3/Bat/Germany/342/08 strain, which was isolated in Germany in 2008. The MReo2045 isolate will be useful as an antigen for sero-epidemiological studies and developing diagnostic tools.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.733-739
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• 2021

Acinetobacter strains are widely present in the environment. Some antimicrobial-resistant strains of this genus have been implicated in infections acquired in hospitals. Genetic similarities have been reported between Acinetobacter strains in nosocomial infections and those isolated from foods. However, the antimicrobial resistance of Acinetobacter strains in foods, such as meat, remains unclear. This study initially aimed to isolate Campylobacter strains; instead, strains of the genus Acinetobacter were isolated from meat products, and their antimicrobial resistance was investigated. In total, 58 Acinetobacter strains were isolated from 381 meat samples. Of these, 32 strains (38.6%) were from beef, 22 (26.5%) from pork, and 4 (4.8%) from duck meat. Antimicrobial susceptibility tests revealed that 12 strains were resistant to more than one antimicrobial agent, whereas two strains were multidrug-resistant; both strains were resistant to colistin. Cephalosporin antimicrobials showed high minimal inhibitory concentration against Acinetobacter strains. Resfinder analysis showed that one colistin-resistant strain carried mcr-4.3; this plasmid type was not confirmed, even when analyzed with PlasmidFinder. Analysis of the contig harboring mcr-4.3 using BLAST confirmed that this contig was related to mcr-4.3 of Acinetobacter baumannii. The increase in antimicrobial resistance in food production environments increases the resistance rate of Acinetobacter strains present in meat, inhibits the isolation of Campylobacter strains, and acts as a medium for the transmission of antimicrobial resistance in the environment. Therefore, further investigations are warranted to prevent the spread of antimicrobial resistance in food products.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.1
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• pp.106-122
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• 2021

This study confirmed the mechanical properties of an auxetic re-entrant pattern prepared using 3D printing technology and its composite fabric with neoprene for the production of functional auxetic patterns/textiles for safety shoes. Samples were prepared by the tilt angle of a re-entrant pattern of 0°, 30°, 45°, 60° and 90°, and then analyzed using Poisson's ratio, bending, compression, and tensile properties. A 3D printed auxetic re-entrant pattern (3DP-RE) and its composite fabric (3DP-RE/NP) showed a negative Poisson's ratio in all tilting angles that indicated auxetic properties. The results of the bending property shown that strength of 3DP-RE/NP was 1.5 times lower than NP, but the strain improved 2.0 times. It was confirmed that the deformation of 3DP-RE/NP is possible with a low load. Each sample type of compression behavior indicated similar regardless of the tilting angles; in addition, the compression toughness of 3DP-RE/NP increased 1.2 times compared with NP. In the case of tensile properties, 3DP-RE and 3DP-RE/NP were affected by the tilting angle, samples with 90° (the opposite of load direction) showed best tensile property and toughness. 3DP-RE/NP indicated improved bending, compression, and tensile properties.

• Geomechanics and Engineering
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• v.24 no.4
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• pp.323-335
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• 2021

This paper aims to estimate the range of the excavation damaged zone (EDZ) formation caused by the tunnel boring machine (TBM) advancement through dynamic three-dimensional large deformation finite element analysis. Large deformation analysis based on Coupled Eulerian-Lagrangian (CEL) analysis is used to accurately simulate the behavior during TBM excavation. The analysis model is verified based on numerous test results reported in the literature. The range of the formed EDZ will be suggested as a boundary under various conditions - different tunnel diameter, tunnel depth, and rock type. Moreover, evaluation of the integrity of the tunnel structure during excavation has been carried out. Based on the numerical results, the apparent boundary of the EDZ is shown to within the range of 0.7D (D: tunnel diameter) around the excavation surface. Through series of numerical computation, it is clear that for the rock of with higher rock mass rating (RMR) grade (close to 1st grade), the EDZ around the tunnel tends to increase. The size of the EDZ is found to be direct proportional to the tunnel diameter, whereas the depth of the tunnel is inversely proportional to the magnitude of the EDZ. However, the relationship between the formation of the EDZ and the stability of the tunnel was not found to be consistent. In case where the TBM excavation is carried out in hard rock or rock under high confinement (excavation under greater depth), large range of the EDZ may be formed, but less strain occurs along the excavation surface during excavation and is found to be more stable.

• The Korean Journal of Food And Nutrition
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• v.34 no.6
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• pp.604-611
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• 2021

In this study, we investigated the effects of adding oat and lactic acid bacteria on the quality and functionality of yogurt. Yogurt was fermented with various lactic acid bacteria,; Lactobacillus acidophilus (LA), Lactobacillus delbrueckii sub. bulgaricus (LB), and Streptococcus thermophilussei (ST) and quality properties, β-glucan content, antioxidant activity were estimated. The quality of control and oat added yogurt (OY) showed significant differences depending on the type of strain and combination. The addition of oats significantly accelerated the lactic acid bacteria production, decreased the pH, and increased the titratable acidity and count of the viable cells compared to the control. Acid production was highest in ST, with the complex strains containing ST and LALBST showing high quality characteristics. The viscosity of oat yogurt was higher than that of the control group, and LALBST was also significantly higher than that of the control group. The β-glucan content of OY was 0.14-0.2%, and the organic acid content and antioxidant activity were also significantly increased by the addition of oats. As a result, it is thought that the addition of oats and a combination of lactic acid bacteria can be used for improving the quality and functionality of yogurt.