• Korean Journal of Microbiology
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• v.29 no.2
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• pp.75-79
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• 1991

The yeast L-A virus (4.6 kb dsRNA genome) encodes the major coat protein and a "gag-pol" fusion minor coat protein that separately encapsidate itself and $M_{1}$, a 1.8 kb dsRNA satellite virus encoding a secreted protein toxin (the killer toxin). The teast chromosomal SKI genes prevent viral cytopathology by lowering the virus copy number. Thus, $ski^{-}$ mutants are ts and cs for growth. We transformed a ski2-2 virus-infested mutant with a yeast bank in a high copy cloning vector and selected the rare healthy transformants for analysis. One type of transformant segregated M-O L-A-O cells with high frequency. Elimination of the DNA clone from the ski2-2 strain eliminated this phinotype and introduction of the DNA clone recovered from such transformants into the parent ski2-2 strain, or into ski3 or ski6 mutants gave the same phenotype. This killer-curing phenotype was due to the curing of the helper L-A dsRNA virus. The 6.5 kb insert only had this activity when carried on a high copy vector and in $ski^{-}$ cells (not in $SKI^{+}$ cells). This 6.5 kb insert acts as a mutagen on L-A dsRNA producing a high rate of deletion mutations.mutations.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.669-675
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• 1998

Taq DNA polymerase exhibits a sizable drawback compared to the other thermophilic DNA polymerases in that it demonstrates lower proof-reading activity due to the deficiency of 3'-5'exonuclease activity. A study was undertaken to improve the 3'-5' exonuclease activity in the PCR of Taq DNA polymerase. The three-dimensional structural alignment of the polymerase and 3'-5' exonuclease domains from the pol I family DNA polymerases explains why Taq DNA polymerase has just a background level of 3'-5'exonuclease activity. A comparison indicated that the two polymerase domains are very similar in primary and tertiary conformations, even though Taq DNA polymerase carries a much shorter 3'-5'exonuclease domain than that of E. coli DNA polymerase I. Those two polymerase domains were interchanged between Taq DNA polymerase and E. coli DNA polymerase I. The 3'-5' exonuclease domain from E. coli DNA polymerase I was separated and pasted into the polymerase domain of Taq DNA polymerase I, which resulted in a functional fusion-Stoffel fragment. The 3'-5'exonuclease activity of the fusion-Stoffel fragment increased up to 48% of the value of the Klenow fragment, while that of Taq DNA polymerase remained at 6.0% of the Klenow fragment.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.624-627
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• 2003

Benzo[a]pyrene (B[a]P) is an environmental pollutant that has been implicated in carcinogenesis. Saccharomyces cerevisiae was treated with B[a]P, and the responses of its cytochrome P450 (CYP) enzyme and DNA-damage checkpoint genes were examined through gene expression profiles using a reverse transcription polymerase chain reaction (RT-PCR). The DNA-damage checkpoint genes tested were the chk1 and pds1 genes, involved in a metaphase arrest, the swi6 gene targeted by G1 arrest, the pol2 gene related to S phase arrest, and the cln2 gene encoding a cyclin protein, all of which are based on rad9 and rad24. Among these genes, no noticeable effect was found when the cells were exposed to various concentrations of B[a]P. However, the transcriptional activity of CYP51 was significantly different when the cells were exposed to B[a]P. Accordingly, the present results indicate that cytochrome P450 plays a more significant role than DNA-damage checkpoint genes in the response of S. cerevisiae to B[a]P.

• Wind and Structures
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• v.7 no.4
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• pp.251-264
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• 2004

The effects of a class of nonlinear Tuned Mass Dampers on the aeroelastic behavior of SDOF systems are investigated. Unlike classical linear TMDs, nonlinear constitutive laws of the internal damping acting between the primary oscillator and the TMD are considered, while the elastic properties are keept linear. The perturbative Multiple Scale Method is applied to derive a set of bifurcation equations in the amplitude and phase and a parametric analysis is performed to describe the postcritical scenario of the system. Both cubic- and van der Pol-type dampings are considered and the dependence of the limit-cycle amplitudes on the system parameters is studied. These new results, compared with the previously obtained bifurcation scenario of a SDOF aeroelastic oscillator equipped with a linear TMD, show a detrimental effect on the maximum limit-cycle amplitude reduction of the nonlinear TMD. However, the analyses evidence that in the parameter region away from the perfect tuning condition the nonlinear connection can be used to tune the system with an enhancement of the limit-cycle amplitude reduction.

• Steel and Composite Structures
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• v.22 no.4
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• pp.777-796
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• 2016

In this paper, the behavior of woven E-glass fabric composite laminate was experimentally investigated under quasi-static indentation and high velocity impact by flat-ended, hemispherical, conical (cone angle of $37^{\circ}$ and $90^{\circ}$) and ogival (CRH of 1.5 and 2.5) cylindrical perforators. Moreover, the results are compared in order to explore the possibility of extending quasi-static indentation test results to high velocity impact test results in different characteristics such as perforation mechanisms, performance of perforators, energy absorption, friction force, etc. The effects of perforator nose shape, nose length and nose-shank connection shapes were investigated. The results showed that the quasi-static indentation test has a great ability to predict the high velocity impact behavior of the composite laminates especially in several characteristics such as perforation mechanisms, perforator performance. In both experiments, the highest performance occurs for 2.5 CRH projectile and the lowest is related to blunt projectiles. The results show that sharp perforators indicate lower values of dynamic enhancement factor and the flat-ended perforator represents the maximum dynamic enhancement factor among other perforators. Moreover, damage propagation far more occurred in high velocity impact tests then quasi-static tests. The highest damage area is mostly observed in ballistic limit of each projectile which projectile deviation strongly increases this area.

• Wind and Structures
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• v.29 no.6
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• pp.441-455
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• 2019

In this study, vortex induced vibrations of a cylinder mounted on a flexible rod are analyzed. This simple configuration represents the key element of new conception bladeless wind turbine (Whitlock 2015). In this study the structure oscillations equation coupled to the wake oscillation equation for this configuration are solved using analytical perturbation method, for the first time. An analytical expression that predicts the lock-in phenomena range of wind speed is derived. The discretized equations of motion are also solved using RKF45 numerical method. The equations of motion are discretized by Galerkin method. Free vibration mode shape of the structure taking into account the discontinuity of the cross section are used as comparison function. Numerical results are compared to the analytical results, and they show a satisfying agreement. The effect of system parameters on the oscillations of structure and wake as well as on the lock-in domain are presented. Moreover, it is shown that the values of wind speed triggering the start and the stop of the lock-in phenomenon, for increasing wind speed are different from those values obtained during the reverse process, i.e., when the wind speed decreases.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.990-998
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• 2007

Adaptive output feedback control technique using Neural Networks(NN) is proposed for uncertain nonlinear Multi-Input Multi-Output(MIMO) systems. Modified Dynamic Inversion Model(MDIM) is introduced to decouple uncertain nonlinearities from inversion-based control input. MDIM consists of approximated dynamic inversion model and inversion model error. One NN is applied to compensate the MDIM of the system. The output of the NN augments the tracking controller which is based upon a filtered error approximation with online weight adaptation laws which are derived from Lyapunov's direct method to guarantee tracking performance and ultimate boundedness. Several numerical results are illustrated in the simulation of Van der Pol system and unmanned helicopter with model uncertainties.

• Applied Biological Chemistry
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• v.31 no.3
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• pp.219-225
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• 1988

Reverse transcriptase gene of Avian sarcoma virus(ASV) was cloned with a thermoinducible expression vector, pPL-lambda. E. coli N4830 which carries temperature sensitive cI857 la mbda repressor, was transformed with this pPL-pol plasmid DNA. The RNA transcribed by those tranoformants was isolated and analyzed. It was shown that the inserted reverse transcriptase gene of ASV was transcribed at high-level when cells were grown at high temperature.

• Korean Journal of Microbiology
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• v.35 no.2
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• pp.107-114
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• 1999

To assess genetic diversity amoug 21 strains from sixleen Frrsn~i~nn species , we used RAPD(rando1n amplified pol.ymorphic DNA) analysis based on PCR(po1ymerase chain reaction). Eleven primers showing Ule polymorphism were chosen from the 40 random pnmers-tcstcd. A total of 263 polymorphic bands were generated by the primers and the size of amplified DNA fragments ranged from 0.1 lo 3.0 kb. Sirnilku-it), coefficients between strains were calcnlatcd, and UPGMA cluster analysis was used to generate a dendrogram showing relationships among them. The results from RAPD-PCR analysis were grouped into four main groups at the si~nilarity level of 0.627.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.67-80
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• 1990

This study was performed for elucidating the effects on surface polishing of composite resins. In this study, Silux(microfilled), Graft(hybrid), Bisfil- I (hybrid posterior) and Hi-pol(conventional) were used. Sixty specimens were made with 4 brands of composite resins and Optilux system in $2.0{\times}1.3{\times}1.0cm$ resin block which has a cavity with 0.5cm diameter and 0.5cm depth. Polishing was done with #600 sand paper and Soflex, Super-snap, Micron finishing system, or Composite polishing kit. Final polished surfaces were measured by roughness tester(Kasaka Lab. Ltd., Japan) and image analyser(Omnimet Image Analyser, Buehler, USA). The results were as follows, 1. The celluloid strip produced the smoothest surfaces. 2. Light curing microfilled composite resin, Silux, had smoother surface than any others. 3. The surfaces polished by Soflex were smoothest. 4. Aluminum oxide disk, Soflex and Super-Snap, made smoother surface than diamond bur, M.F.S., or silicon point, Composite polishing kit. 5. The roughness values of surface polished by M.F.S. composed of diamond burs, were less than those of Composite polishing kit made from silicone points.