• Structural Engineering and Mechanics
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• v.3 no.6
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• pp.611-622
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• 1995

This paper is concerned with inelastic load carrying capacity of tapered steel members with or without accumulated plastic strains resulted from previous loading histories. A finite element program is developed using stiffness matrices of tapered members and is applicable for analyses with material and geometric nonlinearity. Results of analyses are compared with other available solutions and with experimental results.

• Korean Journal of Poultry Science
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• v.27 no.2
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• pp.91-98
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• 2000

Phylogenetic tree constructed from the nucleotide sequences of the S1 gene showed that the 15 Korean strains of infectious bronchitis virus(IBV) examined were classified into 2 genetically distinct groups, except one respiratory strain, RB86, which was clustered with Massachusetts group. All the 5 respiratory strains belonged to Korean group I and the rest 9 nephropathogenic strains belonged to Korean group II according to the analysis, based on S1 gene sequences. Like previous classifications corresponded with the geographic origin, Korean stains were discriminated from geographically distinct reference strains of IBV. The nephropathogenic strains within Korean group IIsharing 96% homology were continuously isolated since 1990, and seemed to be genetically stable. Whereas the respiratory strains within Korean group Ⅰ sharing 88% homology were sporadically isolate since 1986m and seemed to be genetically unstable. Because we found putative accumulated point mutation as well as recombination events in Korean group Ⅰ, we discussed why genetic variations have often occurred in respiratory strains rather than nephropathognic strains.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.85-89
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• 2003

The difference in the thermotolerance between Saccharomyces cerevisiae KNU5377 and ATCC24858 was compared by assaying the amounts of trehalose accumulated under growth and heat shock conditions. Both strains exhibited similar trehalose accumulation during the growth period, but an intrinsic thermotolerance was much higher in KNU5377 than in the control strain. This result implied that some strain-specific characteristics of KNU5377, other than trehalose accumulation, primarily were responsible fur its higher intrinsic thermotolerance. Heat shock at $43^{\circ}C$ for 90 min to the exponentially growing cells resulted in the maximum level of trehalose In both strains. Trehalose accumulated at least twice more in KNU5377 by the heat shock than in the control, due to the maintenance of its neutral trehalase activity even after the heat shock. Consequently, the Increase of acquired thermotolerance in both strains correlated with an increase in the trehalose content in each strain. In conclusion, KNU5377 exhibited a well-modulated trehalose-related mechanism to accumulate more trehalose by means of maintaining neutral trehalase activity after heat shock than the control strain, thereby contributing to its acquired thermotolerance.

• Archives of Pharmacal Research
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• v.18 no.3
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• pp.173-178
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• 1995

Ciprofloxacin resistance mechanisms were studied by investigating the inhibitory effect of ciprofloxacin on the gyrase-mediated DNA supercoiling and the intracellular accumulation of ciprofloxacin in clinical isolates of Pseudomonas aeruginosa. A higher amount of ciprofloxacin was required to inhibit the gyrases purified from the ciprofloxacin-resistant strains than that from the sensitive strain. Reconstitution of heterologous gyrase subunits from different strains revealed alterations in the A and/or the B subunits of gyrase in these strains. In addition, the resistant strains accumulated approximately a half amount of ciprofloxacin inside the cells, compared to the sensitive strain. However, when the active efflux was blocked by carbonyl cyanide m-chlorophenyl hydrazone treatment, intracellular concentration of ciprofloxacin was elevated about 4-7 fold in these strains, while the sensitive strain was not significantly affected by this treatment, indicating that the ciprofloxacin-resistant strains developed a drug efflux system. Interestingly, these resistant strains expressed an envelope protein of approximately 51 kD. These studies suggest that alterations in the gyrase as well as the active drug-efflux system conferred dual ciprofloxacin resistance mechanisms to these clinical isolates of P. aeruginosa.

• Journal of the Korean Chemical Society
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• v.26 no.6
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• pp.396-402
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• 1982

Bacteriophage T4 tRNA processing in E. coli mutant strains defective in RNase Ⅲ, RNase E$^-$, and RNase P, respectively, singly or in combinations, was investigated. In $RNase E^- strains, a RNA band, which would be referred as 9S RNA, accumulates, while in RNase$ P^-$ strains, lower band of 6S double band is accumulated. In RNase III$^-$ strains, the production of tRAN$^{Gln}$ coded by T4 tRNA gene cluster, is severely depressed and also production of species 1 RNA, which is coded by T4 DNA but not by the tRNA gene cluster, is in somewhat depressed amounts; on the other hand, at the same time, an upper band of 6S double bands, coded by T4 tRNA gene cluster, is accumulated in rather greater amounts as compared to the RNase $^+$ strain. The upper band RNA of the 6S double band, however, does not appear to be a precursor to the tRNA$^{Gln}$. The present work points to the lack of evidence for an essential cleavage role of RNase Ⅲ, although there must be a role for the RNase Ⅲ in the T4 tRNA processing.

• The Korean Journal of Zoology
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• v.25 no.2
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• pp.93-106
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• 1982

Proteins, which may be closely related to differentiation of a cell group into a predestined fate, were investigated using imaginal discs of a wing mutant, vestigial of Drosophila melanogaster. The wing discs of the mutant fail to differentiate into normal wings, even though the third instar larvae form wing discs, which are very similar to those of the normal strain in size and shape. Patterns of proteins of accumulated or synthesized in the discs of the third instar larvae of the normal and mutant strains were analyzed by acrylamide gel electrophoresis. The patterns of accumulated proteins were found to be slightly different between two strains in quantity rather than in quality. The patterns of proteins synthesized at various times of the third instar were found to be very similar to each other, even though there were a few proteins specific to the normal or to the mutant strain.

• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.340-346
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• 1994

Six bacterial strains capable to grow on medium containing cholesterol as sole carbon source were isolated from soil, pork fat and cheese. Three of them were tentatively identified as Rhodococcus species, Rhodococcus sp. CD-1, R. sp. CD-2, and R. sp. CD-3. All the isolates showed a varying amount of cholest-4-en-3-one as the degradation product, and three strains of Rhodococcus spp. showed rapid degradation of cholesterol. Radioisotopic studies revealed that cholesterol was degraded to non-sterol hydrophilic compounds via cholest-4-en-3-one, and presumably to C0$_{2}$- These strains showed two distinct patterns in further degradation of cholest-4-en-3-one. By one group, R. sp. CD-1 and R. sp. CD-3, cholest-4-en-3-one was rapidly converted to non-sterol inter- mediates without significant accumulation of sterol derivatives in the culture broth. In contrast, by another group, R. sp. CD-2, the substantial amount of cholest-4-en-3-one was accumulated indica- ting a lower conversion of the compound to the next metabolites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.195-204
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• 2004

A series of constant creep and repeated creep tests are performed to investigate the behavior of visco-elasto-plastic materials of chemical grouted sands. In the result of constant creep test, the material exhibits three types of shear strain : elastic, plastic, viscoelastic. The elastic, plastic and viscoelastic strains are linear, i.e., the strains are proportional to the stresses for loading. Good agreement is found between the predicted viscoelastic and test results by the power law and the generalized model. In the repeated creep test, the instantaneous recoverable strain is time-independent and the magnitude of accumulated plastic strain increases with number of cycles. Also it is seen that the accumulated plastic strains are approximately proportional to stress. There are no significant differences between test results predicted values for first cycle, and the differences increase relatively insignificantly with number of cycles.

• Mycobiology
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• v.51 no.1
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• pp.26-35
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• 2023

The diversity of A mating type in wild strains of Lentinula edodes was extensively analyzed to characterize and utilize them for developing new cultivars. One hundred twenty-three A mating type alleles, including 67 newly discovered alleles, were identified from 106 wild strains collected for the past four decades in Korea. Based on previous studies and current findings, a total of 130 A mating type alleles have been found, 124 of which were discovered from wild strains, indicating the hyper-variability of A mating type alleles of L. edodes. About half of the A mating type alleles in wild strains were found in more than two strains, whereas the other half of the alleles were found in only one strain. About 90% of A mating type combinations in dikaryotic wild strains showed a single occurrence. Geographically, diverse A mating type alleles were intensively located in the central region of the Korean peninsula, whereas only allele A17 was observed throughout Korea. We also found the conservation of the TCCCAC motif in addition to the previously reported motifs, including ATTGT, ACAAT, and GCGGAG, in the intergenic regions of A mating loci. Sequence comparison among some alleles indicated that accumulated mutation and recombination would contribute to the diversification of A mating type alleles in L. edodes. Our data support the rapid evolution of A mating locus in L. edodes, and would help to understand the characteristics of A mating loci of wild strains in Korea and help to utilize them for developing new cultivars.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.383-393
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• 2024

Monopile foundations of offshore wind turbines embedded in soft clay are subjected to the long-term cyclic lateral loads induced by winds, currents, and waves, the vibration of monopile leads to the accumulation of pore pressure and cyclic strains in the soil in its vicinity, which poses a threat to the safety operation of monopile. The researchers mainly focused on the hysteretic stress-strain relationship of soft clay and kinds of stiffness degradation models have been adopted, which may consume considerable computing resources and is not applicable for the long-term bearing performance analysis of monopile. In this study, a modified cyclic stiffness degradation model considering the effect of plastic strain and pore pressure change has been proposed and validated by comparing with the triaxial test results. Subsequently, the effects of cyclic load ratio, pile aspect ratio, number of load cycles, and length to embedded depth ratio on the accumulated rotation angle and pore pressure are presented. The results indicate the number of load cycles can significantly affect the accumulated rotation angle of monopile, whereas the accumulated pore pressure distribution along the pile merely changes with pile diameter, embedded length, and the number of load cycles, the stiffness of monopile can be significantly weakened by decreasing the embedded depth ratio L/H of monopile. The stiffness degradation of soil is more significant in the passive earth pressure zone, in which soil liquefaction is likely to occur. Furthermore, the suitability of the "accumulated rotation angle" and "accumulated pore pressure" design criteria for determining the required cyclic load ratio are discussed.