• The Plant Pathology Journal
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• v.40 no.2
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• pp.151-159
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• 2024

Bacterial soft rot caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) is one of the most severe diseases in radish cultivation. To control this plant disease, the most effective method has been known to cultivate resistant cultivars. Previously, we developed an efficient bioassay method for investigating resistance levels with 21 resistant and moderately resistant cultivars of radish against a strain Pcc KACC 10421. In this study, our research expanded to investigate the resistance of radish cultivars against six Pcc strains, KACC 10225, KACC 10421, ATCC 12312, ATCC 15713, LY34, and ECC 301365. To this end, the virulence of the six Pcc strains was determined based on the development of bacterial soft rot in seedlings of four susceptible radish cultivars. The results showed that the Pcc strains exhibited different virulence in the susceptible cultivars. To explore the race differentiation of Pcc strains corresponding to the resistance in radish cultivars, we investigated the occurrence of bacterial soft rot caused by the six Pcc strains on the 21 resistant and moderate resistant cultivars. Our results showed that the average values of the area under the disease progress curve were positively correlated with the virulence of the strains and the number of resistant cultivars decreased as the virulence of Pcc strains increased. Taken together, our results suggest that the resistance to Pcc of the radish cultivars commercialized in Korea is more likely affected by the virulence of Pcc strains rather than by race differentiation of Pcc.

• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.211-225
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• 2024

Soft bending actuators have gained significant interest in robotic applications due to their compliance and lightweight nature. Their compliance allows for safer and more natural interactions with humans or other objects, reducing the risk of injury or damage. However, the nonlinear behaviour of soft actuators presents challenges in accurately predicting their bending motion and force exertion. In this research, a new comprehensive study has been conducted by employing a developed 3D finite element model (FEM) to investigate the effect of geometrical and material parameters on the bending behaviour of a soft pneumatic actuator reinforced with Kevlar fibres. A series of experiments are designed to validate the FE model, and the FE model investigates the improvement of actuator performance. The material used for fabricating the actuator is RTV-2 silicone rubber. In this study, the Cauchy stress was expanded for hyperelastic models and the best model to express the stress-strain behaviour based on ASTM D412 Type C tensile test for this material has been obtained. The results show that the greatest bending angle was achieved for the semi-elliptical actuator made of RTV2 material with a pitch of 1.5 mm and second layer thickness of 1 mm. In comparison, the maximum response force was obtained for the semi-elliptical actuator made of RTV2 material with a pitch of 6 mm and a second layer thickness of 2 mm. Additionally, this research opens up new possibilities for development of safer and more efficient robotic systems that can interact seamlessly with humans and their environment.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.969-977
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• 2024

Indigo is a valuable, natural blue dye that has been used for centuries in the textile industry. The large-scale commercial production of indigo relies on its extraction from plants and chemical synthesis. Studies are being conducted to develop methods for environment-friendly and sustainable production of indigo using genetically engineered microbes. Here, to enhance the yield of bioindigo from an E. coli whole-cell system containing tryptophanase (TnaA) and flavin-containing monooxygenase (FMO), we evaluated tryptophan transporters to improve the transport of aromatic compounds, such as indole and tryptophan, which are not easily soluble and passable through cell walls. Among the three transporters, Mtr, AroP, and TnaB, AroP enhanced indigo production the most. The combination of each transporter with AroP was also evaluated, and the combination of AroP and TnaB showed the best performance compared to the single transporters and two transporters. Bioindigo production was then optimized by examining the culture medium, temperature, isopropyl β-D-1-thiogalactopyranoside concentration, shaking speed (rpm), and pH. The novel strain containing aroP and tnaB plasmid with tnaA and FMO produced 8.77 mM (2.3 g/l) of bioindigo after 66 h of culture. The produced bioindigo was further recovered using a simple method and used as a watercolor dye, showing good mixing with other colors and color retention for a relatively long time. This study presents an effective strategy for enhancing indigo production using a combination of transporters.

• Journal of Microbiology and Biotechnology
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• v.34 no.3
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• pp.570-579
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• 2024

Root-nodule nitrogen-fixing bacteria are known for being specific to particular legumes. This study isolated the endophytic root-nodule bacteria from the nodules of legumes and examined them to determine whether they could be used to promote the formation of nodules in other legumes. Forty-six isolates were collected from five leguminous plants and screened for housekeeping (16S rRNA), nitrogen fixation (nifH), and nodulation (nodC) genes. Based on the 16S rRNA gene sequencing and phylogenetic analysis, the bacterial isolates WC15, WC16, WC24, and GM5 were identified as Rhizobium, Sphingomonas, Methylobacterium, and Bradyrhizobium, respectively. The four isolates were found to have the nifH gene, and the study confirmed that one isolate (GM5) had both the nifH and nodC genes. The Salkowski method was used to measure the isolated bacteria for their capacity to produce phytohormone indole acetic acid (IAA). Additional experiments were performed to examine the effect of the isolated bacteria on root morphology and nodulation. Among the four tested isolates, both WC24 and GM5 induced nodulation in Glycine max. The gene expression studies revealed that GM5 had a higher expression of the nifH gene. The existence and expression of the nitrogen-fixing genes implied that the tested strain had the ability to fix the atmospheric nitrogen. These findings demonstrated that a nitrogen-fixing bacterium, Methylobacterium (WC24), isolated from a Trifolium repens, induced the formation of root nodules in non-host leguminous plants (Glycine max). This suggested the potential application of these rhizobia as biofertilizer. Further studies are required to verify the N₂-fixing efficiency of the isolates.

• Geomechanics and Engineering
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• v.38 no.2
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• pp.125-137
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• 2024

In paste backfill mining, cemented coal gangue-fly ash backfill (CGFB) can effectively utilize coal-based solid waste, such as gangue, to control surface subsidence. However, given the pressurized water accumulation environment in goafs, CGFB is subject to coupling effects from water pressure and chloride ions. Therefore, studying the influence of pressurized water on the chlorine salt erosion of CGFB to ensure green mining safety is important. In this study, CGFB samples were soaked in a chloride salt solution at different pressures (0, 0.5, 1.5, and 3.0 MPa) to investigate the chloride ion transport characteristics, hydration products, micromorphology, pore characteristics, and mechanical properties of CGFB. Water pressure was found to promote chloride ion transfer to the CGFB interior and the material hydration reaction; enhance the internal CGFB pore structure, penetration depth, and chloride ion content; and fill the pores between the material to reduce its porosity. Furthermore, the CGFB peak uniaxial compression strain gradually decreased with increasing soaking pressure, whereas the uniaxial compressive strength first increased and then decreased. The resulting effects on the stability of the CGFB solid-phase hydration products can change the overall CGFB mechanical properties. These findings are significant for further improving the adaptability of CGFB for coal mine engineering.

• Clinical and Experimental Vaccine Research
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• v.13 no.1
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• pp.54-62
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• 2024

Purpose: Accidental vaccination with a live attenuated low-virulence strain of Miyagi (LOM) vaccine led to the reemergence of classical swine fever virus (CSFV) in Jeju province, South Korea in 2014. To control the continual outbreaks of LOM-derived CSFV, the provincial government launched a provincial mass vaccination project using a CSF-E2 subunit vaccine. We conducted this study to assess the herd immunity level and outcomes of E2 vaccine-based immunization in breeding and growing herds on Jeju Island during 2020-2021. Materials and Methods: A large-scale vaccination trial using the Bayovac CSF-E2 vaccine investigated its efficacy in breeding and growing herds under farm application conditions (10 CSFV-affected and three CSFV-naïve swine farms). Results: The level of herd immunity in each farm was classified into three (S1-S3) and six (G1-G6) profiles in breeding and growing herds, respectively. Immunity monitoring revealed a remarkable improvement in the herd immunity status in all farms. The majority (10/13) of farms, including CSFV-free farms, showed the S1G1 immunity profile in 2021, indicating the appropriate implementation of the advised vaccination regime. Moreover, there were significant decreases in E^rns seropositivity from 100% to 50% and 25.9% to 4.3% at farm and pig levels, respectively. In particular, all farms were confirmed as CSFV free in the growing-finishing herds. Conclusion: Our large-scale trial demonstrated the effectiveness of the E2 subunit vaccine in establishing herd immunity stabilization and eliminating CSFV circulation in the affected farms and highlighted the need for a provincial vaccination policy to regain the CSF-free status on Jeju Island.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.183-193
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• 2006

This study deals with the response of reinforced concrete beams strengthened with carbon fiber sheets. Test beams are subjected to static loading and repeated loading. Based on the static test results of the RC beams strengthened with carbon fiber sheets, repeated loading tests are performed. The variables of repeated loading test are composed of the number of carbon fiber sheets, the existence of U-shaped band at the end for anchoring, and loading rate of repeated loading, etc. Test results show the flexural behavior, the characteristics of strength, the characteristics of ductility, the change of flexural rigidity, and the amount of energy loss of RC beams under monotonic incremental loading and repeated loading. The failure strain of carbon fiber sheets is also estimated under repeated loading. From the experimental results, this work presents a basis of the data needed to analyze and design the static and dynamic flexural response of RC beams strengthened with carbon fiber sheets.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.119-126
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• 2008

In 1980 and 1990's most of residential buildings were constructed with relatively low strength concrete of 18 MPa. And, columns were designed considering only vertical loads. In this study, compressive strength tests for low strength RC columns retrofitted by carbon fiber sheets were carried out. Carbon fiber sheet provides constructability and high tensile strength as well as good corrosion resistance characteristics. A pair of carbon sheets were wrapped with ${\pm}60^{\circ}$ angle with respect to longitudinal direction of RC column to increase structural capacity against axial and lateral load simultaneously. Strength and strain patterns and failure modes of specimens were analyzed and prediction equation of increased compressive strength of RC column confined by carbon fiber sheet was proposed based on regression analysis.

• Journal of fish pathology
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• v.28 no.2
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• pp.63-69
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• 2015

The biological characteristics of Bacillus sp.CPB-St as a probiotic strain to control fish streptococcosis was determined. Based on 16S rRNA sequencing, Bacillus sp.CPB-St was identified as Bacillus pumilus and named B. pumilus CPB-St (Abbreviated as CPB-St). Growth inhibitory activity of CPB-St against Streptococcus spp. was examined at three different incubation temperatures ($20^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$) and three culture media (NA, TSA, and BHIA) based on the diameter of inhibition zone. Its activity (inhibition zone of 11~29 mm) at $20^{\circ}C$ was higher than that (12~21 mm) at $30^{\circ}C$. Its activity (29 mm) in NA media was the same as that (29 mm) in TSA media. However, it was higher than that (22 mm) in BHIA media. The inhibitory activity of CPB-St against Streptococcus spp. was high at pH7. However, its activity was the same at salinity of 0.5% to 3%. CPB-St showed maximum growth after incubation at $25^{\circ}C$ for 48 h. To use CPB-St as probiotics, settlement studies in fish intestine and its efficacy through feeding are needed. CPB-St was highly resistant to gastric juice at pH4 and flounder's bile salt as well as deoxycholic acid at $300{\mu}g/ml$. CPB-St showed optimal viability in 1% NaCl. It showed similar growth in 0% to 7% NaCl. CPB-St could tolerate $-20^{\circ}C$ and $-70^{\circ}C$ for 45 min. There was no difference in the growth of the strain between room temperature and $4^{\circ}C$. Fish diet supplemented with CPB-St could be stored at low temperature without cell loss. Therefore, CPB-St might be used as probiotics to control streptococcosis of fish.

• Korean Journal of Poultry Science
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• v.18 no.1
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• pp.33-42
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• 1991

In order to study effects of the 9round charcoal and organic acid on the egg production, White Leghorn strain(Hyline) layer of 113 week-old were fed control diet during a week of previous feeding and subsquent experimental diets during 12 weeks of experimental feeding . The experimental diets were the basal (control) diet composed of mainly corn-soybean meal, diet (CPB) substituted 0.5％ of ground charcoal with the defatted rice bran of the control, diet (PWV) added 0.1 mM(based on the acetic acid) of wood vinegar in the CPD and diet(PFA) added 0.1 mM (based on the acetic acid) of fermented acetic acid in the CPD. During experimental feeding period, birds (ed control, CPD and PWV diets showed similar feed intake which was shown a decreasing tendency in birds fed PFA diet as the passage of experimental feeding period. Birds fed experimental diets containing ground charcoal were tended to increase egg weight (g/egg) , while which of birds fed CPD was higher(P＜0.05) than that fed control diet. Chicks fed the control, CPD and PWV diets produced 75.9, 75.0 and 75. 9％ of egg, respectively, which were significantly(P＜0.05) higher than those of birds fed PFA. Daily egg mass(g/bird) were reached to 48.6, 49.9 and 49.5g i,1 layer fed the control, CPD and PWV diets, respectively, showing an increasing tendency in layer fed CPD and PWV compared with those of birds fed control, which were significantly (P＜0.05) higher than those of birds fed PFA . Although the effect of experimental diets on the feed efficiency (egg/feed) was not found, which was shown an increasing tendency in layer fed CPD compared with those in control diet. Compared with the incidence of cracked or shelless eggs in birds fed control diet, which were lowered to 37％ in birds fed CPD diet and 70％ in PWV-fed birds and increased to two times in birds fed PFA . The contents of cholesterol in egg was not affected by experimental diets, while birds fed CPD diet increased significantly(P＜0.05) the daily biosynthesis of egg protein and showed a trend to increase the thickness of eggshell and eggshell contents per eggs compared with that of control diet-fed birds. The results indicated that the ground charcoal powder improved the performance of layer.