• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.10-16
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• 2012

The Streptomyces peucetius OIM (Overproducing Industrial Mutant) strain is a recursively-mutated and optimally-screened strain used for the industrial production of polyketide antibiotics, such as doxorubicin (DXR). Using the S. peucetius OIM mutant strain as a surrogate host, a model minimal polyketide pathway for aloesaponarin II, an actinorhodin shunt product, was cloned in a high-copy conjugative plasmid, followed by functional pathway expression and quantitative metabolite analysis. The level of aloesaponarin II production was noted as being significantly higher in the OIM strain than in the wild-type S. peucetius, as well as in the regulatory network-stimulated S. coelicolor mutant strain. Moreover, the aloesaponarin II production level was seen to be even higher in a down-regulator $wblA_{spe}$-deleted S. peucetius OIM strain, implying that the rationally-engineered S. peucetius OIM mutant strain could be used as an efficient surrogate host for the high expression of foreign polyketide pathways.

• Journal of Life Science
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• v.9 no.1
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• pp.14-16
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• 1999

Genetic variability was monitored by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) in dicofol-susceptible (S), dicofol-resistant (R) and its reverse-selected (RS) strains of two-spotted spider mite, of Tetranychus urticae. Before the reverse-selection, RS strain, selected reversely from R strain, was 23-fold resistance ratio at {TEX}$LC_{50}${/TEX} to S strain. The resistance was started to in incline slowly to the resistance level of S strain after one year, and the resistance ratio was 4-fold in the 7 years after then. PCR-amplification of T. urticae DNA showed polymorphism in the amplifications with 12 primers in 100 kinds of arbitrary DNA sequences. RAPD amplification with primer OPR-12 (5`-ACAGGTGCGT-3`) showed amplified bands at 1,000 base pair in the S-and RS-strain, and at 350 base pair in R-strain. The results of polymorphism are genetic variabilities derived from development and selection of resistance in each strain. The peculiarly amplified fragments were guessed to participate in dicofol resistance. From the analysis of genetic similarity, it is inferred the gene composition of S-and RS-strain is much closer than that of R-strain.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.8
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• pp.2572-2592
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• 1996

A low-Reynolds-number second moment turbulence closure was developed with the aid of DNS data. Model coefficients of nonlinear return to isotropy term were derived by use of Cayley-Hamilton theorem and two component turbulence limit condition as the functions of invariances of anisotropy and turbulent Reynolds number. Launder and Tselepidakis' cubic mean pressure strain model was modified to fit the predicted pressure-strain components to the DNS data. Two component turbulence limit condition was the precondition to be satisfied in developing the second moment turbulence closure for the realizable Reynolds stress prediction. But the satisfactions of Reynolds stress level and pressure-strain level of each component were compromised because the satisfaction of both levels was impossible.

• Journal of Microbiology and Biotechnology
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• v.30 no.6
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• pp.793-803
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• 2020

Adaptive laboratory evolution (ALE) is an evolutionary engineering approach in artificial conditions that improves organisms through the imitation of natural evolution. Due to the development of multi-level omics technologies in recent decades, ALE can be performed for various purposes at the laboratory level. This review delineates the basics of the experimental design of ALE based on several ALE studies of industrial microbial strains and updates current strategies combined with progressed metabolic engineering, in silico modeling and automation to maximize the evolution efficiency. Moreover, the review sheds light on the applicability of ALE as a strain development approach that complies with non-recombinant preferences in various food industries. Overall, recent progress in the utilization of ALE for strain development leading to successful industrialization is discussed.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.141-145
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• 2003

The FBG sensors are inserted on the liners of the filament wound pressure tanks. The strains near the welding region of the liners are monitored in the hydro-pressurizing tests. The hydro-pressurizing tests consist of the proof tests at 4500 or 3300 psi and repeated test at the operating pressure, 3000 psi. The FBG sensors work well under $3000\mu\varepsilon$, but the strains calculated from the reflected signals are instable at the high strain level. The transverse compression on the sensor head results in the split of the reflected peaks, and the calculating algorism from the split peaks is not robust under the various signal condition. The FBG sensors fracture near $7500\mu\varepsilon$ level and lose their function permanently.

• International Journal of Human Ecology
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• v.10 no.2
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• pp.1-12
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• 2009

The purpose of this study was to explore the dynamics of stepfamilies and the adjustment difficulties such families may experience. The study describes some sociodemographic characteristics of a sample of 117 stepfamilies. The independent variables were stresses due to adjustment difficulties, which were defined as "role strains". Sociodemographic variables included gender, family income level, length of time since remarriage, type of stepfamily, and the existence of any children born to the new marriage. The dependent variable was the extent of stepfamily adjustment, expressed as a scale. The factors influencing family adjustment included stepparent gender, family income level, type of stepfamily, and various role strain variables (family boundary ambiguity, role conflict, etc.). Practical recommendations for social work are made and possibilities for future research in this area are discussed based on the results of this study.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.71-83
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• 2019

This investigation presented conventional triaxial and creep-permeability tests on sandstones considering thermally-induced damage (TID). The TID had no visible effects on rock surface color, effective porosity and permeability below $300^{\circ}C$ TID level. The permeability enlarged approximately two orders of magnitude as TID increased to $1000^{\circ}C$ level. TID of $700^{\circ}C$ level was a threshold where the influence of TID on the normalized mass and volume of the specimen can be divided into two linear phases. Moreover, no prominent variations in the deformation moduli and peak strength and strain appeared as TID< $500^{\circ}C$ level. It is interesting that the peak strength increased by 24.3% at $700^{\circ}C$ level but decreased by 11.5% at $1000^{\circ}C$ level. The time-related deformation and steady-state creep rate had positive correlations with creep loading and the TID level, whereas the instantaneous modulus showed the opposite. The strain rates under creep failure stresses raised 1-4 orders of magnitude than those at low-stress levels. The permeability was not only dependent on the TID level but also dependent on creep deformation. The TID resulted in large deformation and complexity of failure pattern for the sandstone.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.281-282
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• 2010

In this study, it aimed to analyze relation of stress and strain strain for concrete with various under-loading level at elevated temperature.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.341-348
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• 2001

The effect of initial ${\alpha}^{\prime}$ in STS 304 Stainless Steel on fatigue resistance, and fatigue crack propagation behavior was studied with using C-T specimens. Higher ${\Delta}K_{th}$ was observed in the specimens with the content of 0% initial ${\alpha}^{\prime}$ than in the contents of 2% and 33% initial ${\alpha}^{\prime}$. The difference of da/dN at the same level of ${\Delta}K$ was distinctive in low and intermediate level of ${\Delta}K$ however became less different as the level of ${\Delta}K$ increased. It is because the formation of strain induced martensite occurred readily in lower ${\alpha}^{\prime}$ at the vicinity of the fatigue crack tip, which causes compressive residual stresses resulting in the enhancement of crack closure. In general fatigue cracks propagated transgranular mode and many segments of ridges were observed on the fracture surfaces. At the higher contents of initial ${\alpha}^{\prime}$ appeared the smaller size of ridge segments. Slips in austenite were blocked more frequently by the martensite colonies formed in austenite.

• Advances in concrete construction
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• v.5 no.5
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• pp.539-561
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• 2017

In this study, the effects of initial damage of concrete columns on the post-repair performance of reinforced concrete (RC) columns strengthened with carbon-fiber-reinforced polymer (CFRP) composite are investigated experimentally. Four kinds of compression-damaged RC cylinders were reinforced using external CFRP composite wraps, and the stress-strain behavior of the composite/concrete system was investigated. These concrete cylinders were compressed to four pre-damaged states including low -level, medium -level, high -level and total damage states. The percentages of the stress levels of pre-damage were, respectively, 40, 60, 80, and 100% of that of the control RC cylinder. These damaged concrete cylinders simulate bridge piers or building columns subjected to different magnitudes of stress, or at various stages in long-term behavior. Experimental data, as well as a stress-strain model proposed for the behavior of damaged and undamaged concrete strengthened by external CFRP composite sheets are presented. The experimental data shows that external confinement of concrete by CFRP composite wrap significantly improves both compressive strength and ductility of concrete, though the improvement is inversely proportional to the initial degree of damage to the concrete. The failure modes of the composite/damaged concrete systems were examined to evaluate the benefit of this reinforcing methodology. Results predicted by the model showed very good agreement with those of the current experimental program.