• Mycobiology
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• v.51 no.3
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• pp.169-177
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• 2023

To further explore the molecular mechanism of triterpenoid biosynthesis and acquire high-value strain of Sanghuangporus baumii, the Agrobacterium tumefaciens-mediated transformation (ATMT) system was studied. The key triterpenoid biosynthesis-associated gene isopentenyl diphosphate isomerase (IDI) was transformed into S. baumii by ATMT system. Then, the qRT-PCR technique was used to analyze gene transcript level, and the widely targeted metabolomics was used to investigate individual triterpenoid content. Total triterpenoid content and anti-oxidant activity were determined by spectrophotometer. In this study, we for the first time established an efficient ATMT system and transferred the IDI gene into S. baumii. Relative to the wild-type (WT) strain, the IDI-transformant (IT) strain showed significantly higher transcript levels of IDI and total triterpenoid content. We then investigated individual triterpenoids in S. baumii, which led to the identification of 10 distinct triterpenoids. The contents of individual triterpenoids produced by the IT2 strain were 1.76-10.03 times higher than those produced by the WT strain. The triterpenoid production showed a significant positive correlation with the IDI gene expression. Besides, IT2 strain showed better anti-oxidant activity. The findings provide valuable information about the biosynthetic pathway of triterpenoids and provide a strategy for cultivating high-value S. baumii strains.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.177-183
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• 2007

Using complementation of RpoH deficient E. coli strain A7448, the rpoH gene encoding heat shock sigma factor 32 (${\sigma}^{32}$) from Methylovorus sp. strain SS1 DSM11726 was cloned and sequenced. Sequence analysis of a stretch of 1,796-bp revealed existence of an open reading frame encoding a polypeptide of 284 amino acid (32,006 dalton). Deduced amino acid sequence of the Methylovorus sp. strain SS1 RpoH showed that 59.6%, 39.1% and 51.4% identities with those of Nitrosomonas europaea (${\beta}$-proteobacteria), Agrobacterium tumefaciens ($\alpha$-proteobacteria) and E. coli (${\gamma}$-proteobacteria). The expression level of the functional ortholog of RpoH of Methylovorus sp. strain SS1 was increased transiently after heat induction, further indicating that it functions as a heat shock sigma factor.

• Earthquakes and Structures
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• v.1 no.1
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• pp.129-146
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• 2010

This paper proposes an approximate procedure to estimate seismic displacement capacity - defined as yield displacement times the displacement ductility - of piles in marine oil terminals. It is shown that the displacement ductility of piles is relatively insensitive to most of the pile parameters within ranges typically applicable to most piles in marine oil terminals. Based on parametric studies, lower bound values of the displacement ductility of two types of piles commonly used in marine oil terminals - reinforced-concrete and hollow-steel - with either pin connection or full-moment-connection to the deck for two seismic design levels - Level 1 or Level 2 - and for two locations of the hinging in the pile - near the deck or below the ground - are proposed. The lower bound values of the displacement ductility are determined such that the material strain limits specified in the Marine Oil Terminal Engineering and Maintenance Standard (MOTEMS) are satisfied at each design level. The simplified procedure presented in this paper is intended to be used for preliminary design of piles or as a check on the results from the detailed nonlinear static pushover analysis procedure, with material strain control, specified in the MOTEMS.

• Computers and Concrete
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• v.6 no.5
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• pp.377-390
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• 2009

In this paper an improved one-dimensional frame element for modelling of reinforced concrete beams and columns subjected to impact is presented. The model is developed in the framework of a flexibility fibre element formulation that ignores the shear effect at material level. However, a simple shear cap is introduced at section level to take account of possible shear failure. The effect of strain rate at the fibre level is taken into account by using the dynamic increase factor (DIF) concept for steel and concrete. The capability of the formulation for estimating the element response history is demonstrated by some numerical examples and it is shown that the developed 1D element has the potential to be used for dynamic analysis of large framed structures subjected to impact of air blast and rigid objects.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.238-241
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• 2007

We present an innovative method of multi-physics application involving energetic materials. Energetic materials are related to reacting flows in extreme environments such as fires and explosions. They typically involve high pressure, hish temperature, strong non-linear shock waves, and high strain rate deformation of metals. We use an Eulerian methodology to address these problems. Our approach is naturally free from large deformation of materials that makes it suitable for high strain-rate multi-material interaction problems. Furthermore we eliminate the possible interface smearing by using the level sets. We have devised a new level set based tracking framework that can elegantly handle large gradients typically found in reacting gases and metals. We show several work-in-progress applications of our algorithm including the Taylor impact test, explosive venting and additional confined explosion problems of modem interest.

• Korean journal of applied entomology
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• v.33 no.4
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• pp.242-249
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• 1994

These studles were conducted to investigate the development of chem~cal resistance and cross.resista. nce m dlarnondback moth (Piuteiia xylostella L). The resistance development of diamondback moth greatly vaned under single selection of five insectlades. The tnflumuron and lambda cyhalothnn strains at 8th selected generation showed 374- and 29.l.fold resistant levels. respectively, as compared with the susceptible strain. However, the Baciilus thuringiensis-seleded at 8th selected generatLon exhibited 240-fold resistant level. and the prothiophos-selected at 8th generation revealed 14.3-fold resistant !eve1 while the cartap hydrochloride-selected at 8th generailon showed 9.1-fold resistant level Prothiophos- selected strain showed low cross-resistance level to cartap hydrochloride, while this strain exhibited no cross-resistance of 1.3 to 2.8-fold to other msectlcides. Cartap hydrochlonde- seleded strain showed 19.9-fold. a high cross-resistance to lambda cyhalothrin, but this strain showed 2.2-34 fold, no cross resistance to other insecticide. Lambda cyhalothnn-selected strain exhibited cross-resistance to cartap hydrochlolide and prothiophas. Triflumuron-seleded strain showed 1.3-4.9 fold. no cross-resistance to other ~nsectic~dTe he B. ihuring~ensis-selededs train showed no cross-resistance to other insecticides.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.91-102
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• 1990

The representative tests in this study are performed at a selected site which has the soil layers to analyze the safety and economy of the dynamic analysis for the variable soil conditions. Crosshole test and downhole test of small strain level tests and triaxial test of large strain level test are performed in the soil layers, and in the rock layers, crosshole test and downhole in-situ tests and laboratory sonic test are performed to measure the dynamic shear modulus, damping ratio, and Poisson$\acute{s}$ ratio of the soil and the rock. The correlations between the dynamic soil properties from the tests and the basic soil properties are determined through the regression analysis. The representative design value of the soil is determined by probability analysis of the test results. It is determined from the nonlinear stress-strain model in soils, and the value at small strain level is computed in rocks according to the distribution of the type of soils and the affecting variables. The constitutive value is systematized to be utilized in the analysis of the test results, and computation of the input soil data.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.882-889
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• 2021

In order to use an enzyme industrially, it is necessary to increase the activity of the enzyme and optimize the reaction characteristics through molecular evolution techniques. We used the error-prone PCR method to improve the reaction characteristics of LipCA lipase discovered in Antarctic Croceibacter atlanticus. Recombinant Escherichia coli colonies showing large halo zones were selected in tributyrin-containing medium. The lipase activity of one mutant strain (M3-1) was significantly increased, compared to the wild-type (WT) strain. M3-1 strain produced about three times more lipase enzyme than did WT strain. After confirming the nucleotide sequence of the M3-1 gene to be different from that of the WT gene by four bases (73, 381, 756, and 822), the secondary structures of WT and M3-1 mRNA were predicted and compared by RNAfold web program. Compared to the mean free energy (MFE) of WT mRNA, that of M3-1 mRNA was lowered by 4.4 kcal/mol, and the MFE value was significantly lowered by mutations of bases 73 and 756. Site-directed mutagenesis was performed to find out which of the four base mutations actually affected the enzyme expression level. Among them, one mutant enzyme production decreased as WT enzyme production when the base 73 was changed (T→ C). These results show that one base change at position 73 can significantly affect protein expression level, and demonstrate that changing the mRNA sequence can increase the stability of mRNA, and can increase the production of foreign protein in E. coli.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1180-1187
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• 2007

In the present work, topology optimization method using adaptive inner-front level set method is presented. In the conventional level set based topology optimization method, there exists an incapability for inner-front creation during optimization process. In this regard, as a new attempt to avoid and to overcome the limitation, an inner-front creation algorithm is proposed. In the inner-front creation algorithm, the strain energy density of a structure along with volume constraint is considered. Especially, to facilitate the inner-front creation process during the optimization process, the inner-front creation map which corresponds to the discrete valued function of strain energy density is constructed. In the evolution of the level set function during the optimization process, the least-squares finite element method (LSFEM) is employed. As an application to shell structures, the lightweight design of doubly curved shell and segmented mirror is carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.422-427
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• 2002

This paper focuses on the formulation and validation of an automatic strategy for the selection of the locations and directions of strain gauges to capture at best the modal response of a blade in a series of modes. These locations and directions are selected to render the strain measurements as robust as possible with respect to random mispositioning of the gauges and gauge failures. The approach relies on the evaluation of the signal-to-noise ratios of the gauge measurements from finite element strain data and includes the effects of gauge size. A genetic algorithm is used to find the strain gauge locations-directions that lead to the largest possible value of the smallest modal strain signal-to-noise ratio, in the absence of gauge failure, or of its expected value when gauge failure is possible. A fan blade is used to exemplify the applicability of the proposed methodology and to demonstrate the effects of the essential parameters of the problem, i.e. the mispositioning level, the probability of gauge failure, and the number of gauges.