• 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.

• Safety and Health at Work
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• v.14 no.1
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• pp.85-92
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• 2023

Background: Presenteeism is closely related to work performance, work quality and quantity, and productivity at work. According to the job demand-control-support model, job demand, job control, and support play important roles in presenteeism. The present study investigated job characteristics profiles based on the job demand-control-support model and identify the association between job characteristics profiles and presenteeism. Methods: This secondary data analysis used the Sixth Korean Working Condition Survey, a nationwide cross-sectional dataset. The study included 25,361 Korean wage workers employed in the workplace with two or more workers. Participants were classified into four job characteristics profiles based on the job demand-control-support model, using latent profile analysis, and logistic regression was performed to examine the association between study variables. Results: Overall, 11.0 % of study participants reported experience of presenteeism in the past 12 months. Age, sex, location, monthly income, shift work, work hours, health problems, and sleep disturbances were significantly associated with presenteeism. The rate of presenteeism was the highest in the passive isolate group. The passive collective, active collective, and low-stain collective groups had a 23.0%, 21.0%, and 29.0% lower likelihood of experiencing presenteeism, respectively, than the passive isolate group. Conclusions: The job demand-control-support profiles and the risk of presenteeism were significantly associated. The most significant group that lowered the experience of presenteeism was the low-strain collective group, which had a low level of demand and high levels of control and support. Therefore, we need a policy to reduce job demand and increase job control and support at the organizational and national levels.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.309-316
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• 2010

This paper proposed a nonlocal anisotropic damage model to simulate the behavior of plain and reinforced concrete structures that are predominantly tensile and compressive load. This model based on continuum damage mechanics, used a symmetric second-order tensor as the damage variable. For quasi-brittle materials, such as concrete, the damage patterns were different in tension and in compression. These two damage states were modeled by damage evolution laws ensuring a damage tensor rate proportional to the total strain tensor in terms of principal components. To investigate the effectiveness of proposed model, the double edge notched specimen experimented by nooru-mohamed and reinforced concrete bending beam were analyzed using the implementation of the proposed model. As the results for the simulation, the nonlocal anisotropic damage model with an adequate control of rupture correctly represented the crack propagation for mixed mode fracture. In the structural failure of reinforced concrete bending beam, the proposed model can be showed up to a very high damage level and yielding of the reinforcements.

• Journal of The Geomorphological Association of Korea
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• v.27 no.1
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• pp.33-45
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• 2020

A number of unconsolidated deposits, consisting of a layer of gravels and silt, are found in Dangjeong-ri, Seocheon-gun in the western coast. From below in the stratigraphic sequence, the gravel layer ranging up to a maximum thickness of about 2 meters is interpreted as being formed by fluvial processes of an old channel (Dangjeong S.), and the overlying silt or sandy silt layer of 2 to 3 thickness meters is assumed to be emerged paleo-tidal sediments which was deposited in low tidal-energy environments. As the results of rock surface IRSL datings, the depositional ages of gravels are confirmed as ca. 78,000 ~ 83,000 years BP, indicating that the layer was formed in response to a high-stand sea level of MIS 5a along the Dangjeongcheon estuary. It is presumed that the relative height of 4.5 meter between the altitude of the stream bed (9.5 m) and the altitude of the bedrock boundary in the gravel layer (14 m) indicates the uplift amount since deposition. Paleo-sedimentary environments and an altitude of paleo-shoreline in the study area will be discussed with additional age dating focused on the silt layer.

• Advances in nano research
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• v.16 no.3
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• pp.231-249
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• 2024

When the amplitude of the vibrations is equivalent to that clearance, the vibrations for small amplitudes will really be significantly nonlinear. Nonlinearities will not be significant for amplitudes that are rather modest. Finally, nonlinearities will become crucial once again for big amplitudes. Therefore, the concrete panel system may experience a big amplitude in this work as a result of the high temperature. Based on the 3D modeling of the shell theory, the current work shows the influences of the von Kármán strain-displacement kinematic nonlinearity on the constitutive laws of the structure. The system's governing Equations in the nonlinear form are solved using Kronecker and Hadamard products, the discretization of Equations on the space domain, and Duffing-type Equations. Thermo-elasticity Equations. are used to represent the system's temperature. The harmonic solution technique for the displacement domain and the multiple-scale approach for the time domain are both covered in the section on solution procedures for solving nonlinear Equations. An effective data-driven solution is often utilized to predict how different systems would behave. The number of hidden layers and the learning rate are two hyperparameters for the network that are often chosen manually when required. Additionally, the data-driven method is offered for addressing the nonlinear vibration issue in order to reduce the computing cost of the current study. The conclusions of the present study may be validated by contrasting them with those of data-driven solutions and other published articles. The findings show that certain physical and geometrical characteristics have a significant effect on the existing concrete panel structure's susceptibility to temperature change and GPL weight fraction. For building construction industries, several useful recommendations for improving the thermo-mechanics' behavior of structural concrete panels are presented.

• Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.379-391
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• 2024

Tocopherol, carotenoids, and chlorophyll are the primary components of the antioxidative response in microalgae. Conditions of stress, such salt stress, can trigger the processes responsible for the accumulation of tocopherol and carotene. It has been found that the most difficult part of culturing microalgae is keeping it affordable. This study investigated the effects of different salt types and concentrations on the amount of α-tocopherol, carotenoid derivatives, and flocculation efficiency of Euglena sp. Cultures of Euglena sp. was developed under salt stress conditions of NaCl 200 mM and KCl 200 mM. UV-VIS spectrophotometry was used to confirm the presence of α-tocopherol and carotenoid derivatives under thirteen days of salt stress testing. Increasing salinity has a significant effect on Euglena sp., causing spherical cell morphologies with aspect ratio 1.385 ± 0.031 for NaCl 200 mM and 1.414 ± 0.040 for KCl 200 mM. Increasing salinity also slowing down development with specific growth rate value of 0.171 ± 0.006 per day and 0.122 ± 0.029 per day for NaCl and KCl 200 mM, respectively. Nevertheless, the amount of α-tocopherol in Euglena sp. increases with a high salt concentration; algal cells flocculated more successfully when increasing the salt concentrations (NaCl 200 mM and KCl 200 mM) was added. Due to the inhibition of photosynthetic activity in salt-stressed cells, the control group exhibited higher levels of carotenoid derivatives (ranging from 0.5-1 ㎍/mL) and pheophytin a and b (0.0062 ± 0.001 ㎍/mL and 0.0064 ± 0.001 ㎍/mL) than the group treated with salt stress. In conclusion, salt stress was an effective way to raises the concentration of α-tocopherol and significantly reduce the expense of harvesting Euglena sp.

• Korean Journal of Poultry Science
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• v.44 no.2
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• pp.123-134
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• 2017

This study was conducted to establish new synthetic lines of Korean Native Chicken. We performed $5{\times}5$ diallel crossings with GPS lines of Korean Native Chicken for the selection of parent stock. The production traits including viability, body weight, age at first egg laying, egg weight, hen-day egg production, and hen-housed egg production were measured and analyzed for 25 crosses with 1,157 hens. The heterosis effects of these traits were also estimated. The results showed that the average survival rate during laying periods was 67.7% in the pure lines and 77.1% in the crosses. The 25 cross combinations were shown to be distinctly divided into three groups according to body weight; nine crosses in the high-weight group, 12 crosses in the medium-weight group and four crosses in the light-weight group. The average body weight at 12 weeks of age was $1,873.8{\pm}43.0g$ in the high group, $1,595.4{\pm}56.6g$ in the medium group and $1,152.7{\pm}24.7g$ in the light group, and $1,560.2{\pm}339.3g$ in the pure lines and $1,640.9{\pm}213.7g$ in the crosses. In terms of egg production performance, the age at first egg laying was $139.7{\pm}4.9$ days in the pure lines and $135.8{\pm}5.1$ days in the crosses. The average egg weight was $52.3{\pm}1.6g$ in the pure line and $53.0{\pm}1.6g$ in the crosses. The average hen-housed egg production from 20 to 40 weeks was $58.3{\pm}12.9$ eggs in the pure line and $69.2{\pm}10.4$ eggs in the crosses. The average heterosis effect was 16.9% for survival rate, 5.4% for body weight at 12 weeks, -2.7% for age at first egg laying, 1.3% for egg weight, and 14.3% for hen-day egg production. Generally, the heterosis effect for viability and egg production traits was higher than that for growth trait. On the basis of these results, it is expected that the selection of the HF combination, which had excellent growth performance, is the most desirable as the paternal strain, and the selection of GW and FW combinations, which had excellent laying performance, are preferable as the maternal strain.

• The Korean Journal of Zoology
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• v.13 no.3
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• pp.68-74
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• 1970

In the previous studies, the present author found that high proportion of the follicular oocytes from mouse and rabbit ovaries are able to resume their maturation division in the anterior chamber of the eye in which they have been incubated by auto- or homoplastic transplantation. Especially in the case of the homoplastic transplantation, it was known that no trouble has been detected in the process of resumption of the oval maturation in particular connection with the antigen-antibody reaction between donor and recipient. These findings provide a possibility that the follicular oocytes from various animals would be matured in the eye even after the xenoplastic transplantation. Under such an assumption, the present studies were performed to examine the behavior of the follicular oocytes in the eye chamber of the animals of different species. For the donor of the follicular oocytes, domestic rabbits, albino rats of Sprague-Dowley strain, and albino mice of A-strain bred in our laboratory were used. The oocytes obtained from the ovarian follicules were introduced to the anterior chamber of the eye of different species of animals, with an exception of rabbit in which only the female animals were used as a recipient. The procedures of collection of ova, introduction to the eye, harvest from the eye ball, fixation, and staining were the same as mentioned in the previous reports (Cho, 1967b; Cho and Kim, 1968). The conclusions obtained are summarized as below. 1. The rabbit follicular oocytes are able to mature in the eye chambers of both male mouse and rat, although the proportion of the maturation is lower than when they are incubated autoplastically in the eye. When the ova were incubated in the male mouse eye for 24 hours, 21 per cent of them showed chromosomes at metaphase I and II, whereas the rate was 32 per cent when they were incubated in the eye of the male rat. These are apparently low comparing to the rate of 52 per cent of autoplastic transplantation. 2. When rat follicular oocytes were transferred into the mouse eye chamber and recovered after 24 hours, 43 per cent of them produced the mataphase I and II chromosomes. This proportion was higher than the result of the homoplastic transplantation which yielded 23 per cent of the ova on maturation. 3. The most striking result was found in the experiment with mouse follicular oocytes. Seventy-six per cent of the oocytes resumed their maturation division within 24 hours after they were transferred into the male rat eye chamber, and this figure was significantly high compared to the result o 55 per cent obtained by the homoplastic transplantation. In the rat eye, the induction of the degenerative ova also was low (19%). On the other hand, the proportion of the oval maturation decreased to 45 per cent, while that of degeneration increased 33 per cent when they were incubated in the eye of the female rabbit. 4. It was apparent from the present experiments that the follicular oocytes can reveal their activation to maturation in the eye chamber which contains aqueous humor which is known to be composed of low protein content and of very little gamma-globulin which acts as an antibody(Oser, 1965), and that it shows higher osmolarity than blood serum(Levene, 1958). Taking these properities into consideration the humor may provide unfavourable environment to the cells and tissues incubated in. However, it could be noteworthy finding that only the follicular oocytes in the eye of the different species can grow in healthy condition although the maturation rates are varied with the animal species. The fact that the rabbit follicular oocytes show the lower proportion in maturation may be due to the greater amount of the yolk granules in the egg cytoplasm than those in the mouse and rat oocytes. That the mouse oocytes incubated in the eye of the rat mouse and rat oocytes. That the mouse oocytes incubated in the eye of the rat resumed their maturation process in greater proportion would e explained by the fact that the rat eye chamber particularly provides the better environment to the mouse oocytes than the eye chamber of mouse does.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.542-550
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• 2020

The use of high-strength aluminum alloys for ships and of shore structures has many benefits compared to carbon steels. Recently, high-strength aluminum alloys have been widely used in onshore and of shore industries, and they are widely used for the side shell structures of special-purpose ships. Their use in box girders of bridge structures and in the topside of fixed platforms is also becoming more widespread. Use of aluminum material can reduce fuel consumption by reducing the weight of the composite material through a weight composition ratio of 1/3 compared to carbon steel. The characteristics of the stress strain relationship of an aluminum structure are quite different from those of a steel structure, because of the influence of the welding[process heat affected zone (HAZ). The HAZ of aluminum is much wider than that of steel owing to its higher heat conductivity. In this study, by considering the HAZ generated by metal insert gas (MIG) welding, the buckling and final strength characteristics of an aluminum reinforcing plate against longitudinal compression loads were analyzed. MIG welding reduces both the buckling and ultimate strength, and the energy dissipation rate after initial yielding is high in the range of the HAZ being 15 mm, and then the difference is small when HAZ being 25 mm or more. Therefore, it is important to review and analyze the influence of the HAZ to estimate the structural behavior of the stiffened plate to which the aluminum alloy material is applied.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.241-250
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• 2007

In case of retrofitting a concrete structure subjected to blast load by using retrofit materials such as FRP (fiber-reinforced polymer), appropriate ductility as well as raising stiffness must be obtained. But the previous approximate and simplified models, which have been generally used in the design and analysis of structures subjected to blast load, cannot accurately consider effects on retrofit materials. Problems on the accuracy and reliability of analysis results have also been pointed out. In addition, as the response of concrete and reinforcement on dynamic load is different from that on static load, it is not appropriate to use material properties defined in the previous static or quasi-static conditions to in calculating the response on the blast load. In this study, therefore, an accurate HFPB (high fidelity physics based) finite element analysis technique, which includes material models considering strength increase, and strain rate effect on blast load with very fast loading velocity, has been suggested using LS-DYNA, an explicit analysis program. Through the suggested analysis technique, the behavior on the blast load of retrofitted concrete walls using CFRP (carbon fiber-reinforced polymer) and GFRP (glass fiber-reinforced polymer) have been analyzed, and the retrofit capacity analysis has also been carried out by comparing with the analysis results of a wall without retrofit. As a result of the analysis, the retrofit capacity showing an approximate $26{\sim}28%$ reduction of maximum deflection, according to the retrofit, was confirmed, and it is judged ate suggested analysis technique can be effectively applicable in evaluating effectiveness of retrofit materials and techniques.