• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1550-1554
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• 2008

A hydrogen sulfide $(H_2S)$ detecting tube was developed for the quantitative determination of $H_2S$ produced by yeast during laboratory scale wine fermentations. The detecting tube consisted of a small transparent plastic tube packed with an $H_2S$-sensitive color-indicating medium. The packed medium changed color, with the color change progressing upward from the bottom of the tube, upon exposure to $H_2S$ produced by yeast during fermentation. A calibration study using a standard $H_2S$ gas showed that the length of the portion that darkened was directly related to the quantity of $H_2S$ (${\mu}g$) with a high correlation coefficient ($r^2$=0.9997). The reproducibility of the $H_2S$ detecting tubes was determined with five repetitive measurements using a standard $H_2S$ solution [5.6${\mu}g$/200 ml (28 ppb)], which resulted in a coefficient of variation of 3.6% at this level of $H_2S$. With the sulfide detecting tubes, the production of $H_2S$ was continuously monitored and quantified from laboratory scale wine fermentations with different yeast strains and with the addition of different levels of elemental sulfur to the grape juice. This sulfide detecting tube technology may allow winemakers to quantitatively measure $H_2S$ produced under different fermentation conditions, which will eventually lead winemakers to better understand the specific factors and conditions for the excessive production of $H_2S$ during wine fermentation in a large production scale.

• Tunnel and Underground Space
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• v.25 no.4
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• pp.383-396
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• 2015

It is analyzed the risk of building damage due to ground surface subsidence occurred during constructing a tunnel below buildings in sand-gravel layer. The overburden and the thickness of sand-gravel layer is about 20m and the width and the height of the tunnel are 12m and 8.6m, respectively. The tunnel is pre-reinforced by umbrella method with three rows of long steel pipes and grouting. Surface subsidence is measured at 36 points surrounding buildings and measured data are used to calculate optimized three dimensional subsidence surface. Depending on the building location, deflection ratio and horizontal strain are calculated to evaluate the risk of building damage. No damage occurs at the buildings because of both the small deflection ratios involved 1~4mm subsidence and compressive horizontal strains.

• Tribology and Lubricants
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• v.18 no.3
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• pp.194-203
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• 2002

This paper is the first step fur thermo-mechanical stress analyses of part with coated layer under contact load. A lot of coated material is applied in many structures to endure severe situation, like thermal stresses, high temperature gradients, irradiation, impacts by microscopic meteorites, and so on. In this part we are going to apply the FEM to analyze space parts with a coated layer subjected to a contact load thermo-mechanically. Coating layer is very thin in comparision with the structure, therefore it should take more times and behaviors to analyze whole model. In these reason we develop the FEM method of analyzing part with coated layer under contact load using partial model. Steady state temperature distribution of the part is obtained first, and then we apply quasi-static external load on the part. To obtain the final stage of solution, we compute the total solution, and by subtracting the thermal strain from the total ones we get the mechanical strains to compute stresses of the parts. In using the FEM, one has to discretize the model into many sub-domain, finite elements. The method is consisited of two steps. First step is to analyze the whole model with rather coarse meshes. Second step we cut a small region near the loading point, and analyze with very fine meshes. This method is allowable by the Saint-Venant's principle. And then, we finally shall check the therma1 load on the stresses of the space part with coating layer with or without substrate cracks. Then, we predict the actual behaviors of the part used in space.

• Research in Plant Disease
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• v.19 no.4
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• pp.300-307
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• 2013

This study was conducted to determine the occurrence of leaf rot and leaf ring spot, caused by Rhizoctonia solani in Chinese cabbage under seedling nursery and cultivation greenhouses. Symptoms of leaf rot and leaf ring spot were found in three Chinese cabbage cultivars, Brassica campestris subsp. pekinensis, 'Ryeokgwang', 'Daetong', and 'CR mat'. In Hwacheon, the disease incidence was 73.8% in the seedling stage of the Chinese cabbage. In Icheon, the symptoms were observed on the upper leaves of the Chinese cabbage cultivar, 'Norangmini' with 20.5% of disease incidence. The symptoms appeared as primary lesions consisting of small, circular necrotic ring spots with gray color, 1.4-3.0 mm in diameter, accompanied by secondary rot lesions with large irregular borders of leaves. The color of mycelial mat of 20 isolates was dark brown and light brown. The average hyphal diameter of all the isolates was within 5.01-11.12 ${\mu}m$. Among the 20 strains isolated from Chinese cabbage, 16 isolates and four isolates anastomosed with the AG-1 (IB) and AG-1 (IC), respectively. Twenty isolates tested were only virulent on foliage parts of Chinese cabbage leaves but were avirulent on stem parts of the plants. Based on the mycological characteristics and pathogenicity test on host plants, the fungus was identified as Rhizoctonia solani.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.428-439
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• 2020

Erwinia pyrifoliae is a Gram-negative bacterial plant pathogen that causes black shoot blight in apple and pear. Although earlier studies reported the genome comparison of Erwinia species, E. pyrifoliae strains for such analysis were isolated in 1996. In 2014, the strain E. pyrifoliae EpK1/15 was newly isolated in the apple tree showing black shoot blight in South Korea. This study aimed to better understand the similarities and differences caused by natural variations at the genomic level between newly isolated E. pyrifoliae EpK1/15 and the strain Ep1/96, which were isolated almost 20 years apart. Several comparative genomic analyses were conducted, and Clusters of Orthologous Groups of proteins (COG) database was used to classify functional annotation for each strain. E. pyrifoliae EpK1/15 had similarities with the Ep1/96 strain in stress-related genes, Tn3 transposase of insertion sequences, type III secretion systems, and small RNAs. The most remarkable difference to emerge from this comparison was that although the draft genome of E. pyrifoliae EpK1/15 was almost conserved, Epk1/15 strain had at least three sorts of structural variations in functional annotation according to COG database; chromosome inversion, translocation, and duplication. These results indicate that E. pyrifoliae species has gone natural variations within almost 20 years at the genomic level, and we can trace their similarities and differences with comparative genomic analysis.

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.959-966
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• 2004

Twenty-three cultures of harmful algal bloom (HAB)-(causing dinoflagellates were isolated from the coastal waters of Korea. For each of the 14 morphospecies, the nuclearencoded small subunit (SSU) rDNA was analyzed to determine the phylogenetic relatedness of the species. Despite temporal and spatial isolation, 3-4 clonal cultures of Alexandrium catenella, Cochlodinium polykrikoides, and Gymnodinium catenatum had 100% identical SSU rDNA sequences. In contrast, heterogeneities in the SSU rDNA sequences were observed in Akashiwo sanguinea and Lingulodinium polyedrum strains. Extreme sequence polymorphism was shown within the SSU rRNA genes of an Al. tamarense clonal culture. A homology search in GenBank revealed that 11 dinoflagellate species were located in clusters corresponding to their morphological classification. The SSU rDNA sequences of C. polykrikoides, Gyrodinium instriatum, and Pheopolykrikos hartmannii, which were determined for the first time in this study, showed the following phylogenetic relationships: C. polykrikoides formed an independent branch separated from other dinoflagellates; Gyr. instriatum was placed in a monophyletic group with Gyr. dorsum and Gyr. uncatenum; and Ph. hartmanii, which forms a distinct two-celled pseudocolony, belonged to Gymnodinium sensu Hansen and Moestrup.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.29-36
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• 2008

In this paper, the orbital forming analysis of an automotive hub bearing was studied to predict forming performances using the explicit finite element method. To find an efficient solution technique for the orbital forming, axisymmetric finite element models and 3D solid element models were solved and numerically compared. The time scaling and mass scaling techniques were introduced to reduce the excessive computational time caused by small element size in case of the explicit finite element method. It was found from the numerical simulations on the orbital forming that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations at the inner race of bearing were quite different. Finally the strains at the inner race of bearing and the forming forces to the peen were measured for the same product of the numerical model by test, and were compared with the 3D solid element results. It was founded that the test results were in good agreements with the numerical ones.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1028-1038
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• 2005

To elucidate phylogenetic relationships of Phellinus and its related genera, nuclear internal transcribed spacer and mitochondrial small subunit ribosomal DNA sequences from 65 strains were determined and compared. The combined dataset of two sequences increased informative characters and led to the production of trees with higher levels of resolution. Phylogenetic analysis of the combined dataset revealed thirteen evolutionary lineages and several unresolved species that were together subdivided into two large clusters consisting of oligonucleate species and binucleate species. These results coincided with previous cytological, morphological, and molecular studies. It is newly recognized that the Phellinus linteus complex forms a sister clade to Inonotus, and that Fulvifomes is somehow related to Inocutis. The Phellinus linteus complex of dimitic perennial taxa made an independent clade from Inonotus and suggested that hyphal miticity and fruitbody permanence had enough phylogenetic significance to keep the complex within the traditional genus Phellinus. Taxa lacking setae were clustered into Fulvifomes, Phylloporia, Inocutis, and Fomitiporia, and the first three were closely related sister groups, but Fomitiporia was a genus distantly related to them. Several taxa with branched setae were shown among distantly related genera. Molecular evidence indicated that the ancestral nuclear type could be a binucleate feature, and that there might be parallel gains of branched setae and parallel losses of setae in the Hymenochaetales.

• Journal of Microbiology and Biotechnology
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• v.30 no.4
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• pp.497-504
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• 2020

For control of brucellosis in small ruminants, attenuated B. melitensis Rev1 is used but it can be virulent for animals and human. Based on these aspects, it is essential to identify potential immunogens to avoid these problems in prevention of brucellosis. The majority of OMPs in the Omp25/31 family have been studied because these proteins are relevant in maintaining the integrity of the outer membrane but their implication in the virulence of the different species of this genus is not clearly described. Therefore, in this work we studied the role of Omp31 on virulence by determining the residual virulence and detecting lesions in spleen and testis of mice inoculated with the B. melitensis LVM31 mutant strain. In addition, we evaluated the conferred protection in mice immunized with the mutant strain against the challenge with the B. melitensis Bm133 virulent strain. Our results showed that the mutation of omp31 caused a decrease in splenic colonization without generating apparent lesions or histopathological changes apparent in both organs in comparison with the control strains and that the mutant strain conferred similar protection as the B. melitensis Rev1 vaccine strain against the challenge with B. melitensis Bm133 virulent strain. These results allow us to conclude that Omp31 plays an important role on the virulence of B. melitensis in the murine model, and due to the attenuation shown by the strain, it could be considered a vaccine candidate for the prevention of goat brucellosis.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2082-2089
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• 2015

Avian beta-defensin 9 (AvBD9) is a small cationic peptide consisting of 41 amino acids that plays a crucial rule in innate immunity and acquired immunity in chickens. Owing to its wide antibacterial spectrum, lack of a residue, and failure to induce bacterial drug resistance, AvBD9 is expected to become a substitute for conventional antibiotics in the livestock and poultry industries. Using the preferred codon of Pichia pastoris, the mature AvBD9 peptide was designed and synthesized, based on the sequence from GenBank. The P. pastoris constitutive expression vector pGHKα was used to construct a pGHKα-AvBD9 recombinant plasmid. Restriction enzyme digestion was performed using SacI and BglII to remove the ampicillin resistance gene, and the plasmid was electrotransformed into P. pastoris GS115. High-expression strains with G418 resistance were screened, and the culture supernatant was analyzed by Tricine-SDS-PAGE and western blot assay to identify target bands of about 6 kDa. A concentrate of the supernatant containing AvBD9 was used for determination of antimicrobial activity. The supernatant concentrate was effective against Escherichia coli, Salmonella paratyphi, Salmonella pullorum, Pseudomonas aeruginosa, Enterococcus faecalis, and Enterobacter cloacae. The fermentation product of P. pastoris carrying the recombinant AvBD9 plasmid was adjusted to 1.0 × 10⁸ CFU/ml and added to the drinking water of white feather broilers at different concentrations. The daily average weight gain and immune organ indices in broilers older than 7 days were significantly improved by the AvBD9 treatment.