• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.159-160
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• 2014

본 논문에서는 ${\Delta}$결선으로 구성된 Modular Multilevel Converter(MMC)에서 흐르는 전류가 매우 적은 경우 계통에 영향이 없이 셀 직류전압의 불평형을 제어할 수 있도록 영상분전류를 주입하는 방법을 제안하였고, 시뮬레이션을 통해 검증하였다.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.143-146
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• 1991

A new synthetic sequence for the chiral lactone moiety of compactin was developed from $\alpha$-D-glucose in 9 steps via simultaneous reductive detosylation and epoxide-ring opening of 2, 3-epoxy-4-tosylate using NaBH_4$ to afford 2, 4-dideoxy sugar as a key intermediate.

• Journal of The Korean Astronomical Society
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• v.31 no.2
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• pp.101-104
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• 1998

We have obtained photometry of stars in NGC 2264 with several combinations of H$\alpha$ filters and continuum filters. The main purpose of these observations was to determine the best filter combination for selecting low ma!,s member stars in their Pre-Main Sequence (PMS) stage using H$\alpha$ photometry. A narrow band H$\alpha$ filter (${\Delta}{\lambda}$ = $l0{\AA}$) with any combination of continuum filters showed the highest resolution in the H$\alpha$ photometry.

• Journal of Life Science
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• v.27 no.12
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• pp.1403-1409
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• 2017

In this study, the xylitol dehydrogenase (XYL2) gene was expressed in Saccharomyces cerevisiae as a host cell for ease of use in the degradation of lignocellulosic biomass (xylose). To select suitable expression systems for the S.XYL2 gene from S. cerevisiae and the P.XYL2 gene from Pichia stipitis, $pGMF{\alpha}-S.XYL2$, $pGMF{\alpha}-P.XYL2$, $pAMF{\alpha}-S.XYL2$ and $pAMF{\alpha}-P.XYL2$ plasmids with the GAL10 promoter and ADH1 promoter, respectively, were constructed. The mating factor ${\alpha}$ ($MF{\alpha}$) signal sequence was also connected to each promoter to allow secretion. Each plasmid was transformed into S. cerevisiae $SEY2102{\Delta}trp1$ strain and the xylitol dehydrogenase activity was investigated. The GAL10 promoter proved more suitable than the ADH1 promoter for expression of the XYL2 gene, and the xylitol dehydrogenase activity from P. stipitis was twice that from S. cerevisiae. The xylitol dehydrogenase showed $NAD^+$-dependent activity and about 77% of the recombinant xylitol dehydrogenase was secreted into the periplasmic space of the $SEY2102{\Delta}trp1/pGMF{\alpha}-P.XYL2$ strain. The xylitol dehydrogenase activity was increased by up to 41% when a glucose/xylose mixture was supplied as a carbon source, rather than glucose alone. The expression system and culture conditions optimized in this study resulted in large amounts of xylitol dehydrogenase using S. cerevisiae as the host strain, indicating the potential of this expression system for use in bioethanol production and industrial applications.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.194-199
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• 2002

Many oxidative metabolites of tetrahydrocannabinols (THCs), active components of marijuana, were pharmacologically active, and 11-hydroxy-THCs, 11-oxo-${\Delta}^8$-THC, 7-oxo-${\Delta}^8$-THC, 8$\beta$, 9$\beta$-epoxyhexahydrocannabinol (EHHC), 9$\alpha$, l0$\alpha$-EHHC and 3'-hydroxy-${\Delta}^9$-THC were more active than THC in pharmacological effects such as catalepsy, hypothermia and barbiturate synergism in mice. Cannabidiol (CBD), another major component, was biotransfomred to two novel metabolites, 6-hydroxymethyl-${\Delta}^9$-THC and 3-pentyl-6, 7, 7a, 8, 9, lla-hexahydro-I, 7-dihydroxy-7, 1O-dimethyldibenzo[b, d]oxepin (PHDO) through 8R, 9-epoxy-CBD and 85, 9-epoxy-CBD, respectively. Both metabolites exhibited some pharmacological effects comparable to d9 - THe. Cannabinol (CBN), the other major component, was mainly metabolized to ll-hydroxy-CBN by hepatic microsomes of animals including humans. The pharmacological effects of the metabolite were higher than those of CBN demonstrating that II-hydroxylation of CBN is metabolic activation pathway of the cannabinoid as is the case in THCs. Tolerance and reciprocal cross-tolerance developed to pharmacological effects d8 - THC and ll-hydroxy-d8-THC , and the magnitude of tolerance development produced by the metabolite was significantly higher than that by d8-THC. The results indicate that ll-hydroxy-d8-THC has an important role not only in the pharmacological effects but also its tolerance development of d8 - THe. THCs and their metabolites competed to the specific binding of CP-55, 940, an agonist of cannabinoid receptor, to synaptic membrane from bovine cerebral cortex. The Ki value of THCs and their metabolites were closely paralleled to their pharmacological effects in mice. A novel cytochrome P450 (cyp2c29) was purified and identified as a major enzyme responsible for the metabolic activation of d8-THC at the II-position in the mouse liver. cDNA of CYP2C29 was cloned from a mouse cDNA library and its sequence was determined. The oxidation mechanism of THC by cyp2c29 was proposed.

• BMB Reports
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• v.45 no.1
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• pp.32-37
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• 2012

Alternative splicing generates several interleukin-6 (IL-6) isoforms; for them an antagonistic activity to the wild-type IL-6 has been proposed. In this study we quantified the relative abundance of IL-6 mRNA isoforms in a panel of mouse tissues and in C2C12 cells during myoblast differentiation or after treatment with the $Ca^{2+}$ ionophore A23187, the AMP-mimetic AICAR and TNF-${\alpha}$. The two mouse IL-6 isoforms identified, IL-6${\delta}$5 (deletion of the first 58 bp of exon 5) and IL-6${\delta}$3 (lacking exon 3), were not conserved in rat and human, did not exhibit tissue specific regulation, were expressed at low levels and their abundance closely correlated to that of full-length IL-6. Species-specific features of the IL-6 sequence, such as the presence of competitive 3' acceptor site in exon 5 and insertion of retrotransposable elements in intron 3, could explain the production of IL-6${\delta}$5 and IL-6${\delta}$3. Our results argued against biological significance for mouse IL-6 isoforms.

• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.26-35
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• 1997

This paper deals with establishing correspondent points of feature pints and sampling period when we estimate object motion parameters from image information of freely moving objects in space of gravity-free state. Replacing the inertial coordinate system with the camera coordinate system which is equipped within a space robot, it is investigated to be able to analyze a problem of correspond points from image information, and to obtain sequence of angular velocity $\omega$ which determine a motion of object by means of computer simulation. And if a sampling period ${\Delta}t$ is shortened, the relative errors of angular velocity are increased because the relative errors against moving distance of feature points are increased by quantization. In reverse, if a sampling period ${\Delta}t$ is lengthened too much, the relative error are likewise increased because a sampling period is long for angular velocity to be approximated, and we confirmed the precision that grows according to ascending of resolution.

• Journal of The Korean Astronomical Society
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• v.18 no.2
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• pp.41-69
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• 1985

For the well observed 16 globular clusters with known metal abundance (Z), the helium abundances (Y) and ages are determined by various methods, and the relations between Y, Z and age are examined. The luminosity $L_{RR}$ of RR Lyrae stars is known to be dependent of evolutionary models and pulsation theory in the sense that the pulsation theory and horizontal branch (HB) models yield the anticorrelation between $L_{RR}$ and Z whereas main sequence (MS) and red giant branch (RGB) models yield the direct correlation between them. Similarly the anticorrelation between Y and Z is obtained from the HB models and pulsation theory whereas the direct correlation between them is obtained when the RGB model is applied. The current evolutionary models yield the anticorrelation between Z and age of clusters whenever the direct correlation between Y and Z holds. However when the anticorrelation between Y and Z is applied for age determination, the similar age of clusters is obtained as shown by Sandage (1982b). The ages, which are determined by the fitting of C-M diagrams to isochrones in the ($M_v$, B-V)-plane, suggest the two different chemical enrichment processes, which could be accounted for by the disk-halo model for the chemical evolution of the Galaxy (Lee and Ann 1981). Also it is known that the R-method is very useful for Y-determination and the derived Y's show the increasing rate of $\frac{{\Delta}Y}{{\Delta}Z}{\simeq}0.5$ which is comparable to the observed value of $\frac{{\Delta}Y}{{\Delta}Z}{\simeq}0.3$ from HII regions and planetary nebulae by Peimbert and Torres-Peimbert (1976). In this case, the age-metallicity relation of globular clusters could be explained by the disk-halo model.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.304-312
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• 2013

The thermotolerant methylotrophic yeast Hansenula polymorpha is attracting interest as a potential strain for the production of recombinant proteins and biofuels. However, only limited numbers of genome engineering tools are currently available for H. polymorpha. In the present study, we identified the HpPOL3 gene encoding the catalytic subunit of DNA polymerase ${\delta}$ of H. polymorpha and mutated the sequence encoding conserved amino acid residues that are important for its proofreading 3'${\rightarrow}$5' exonuclease activity. The resulting $HpPOL3^*$ gene encoding the error-prone proofreading-deficient DNA polymerase ${\delta}$ was cloned under a methanol oxidase promoter to construct the mutator plasmid pHIF8, which also contains additional elements for site-specific chromosomal integration, selection, and excision. In a H. polymorpha mutator strain chromosomally integrated with pHIF8, a $URA3^-$ mutant resistant to 5-fluoroorotic acid was generated at a 50-fold higher frequency than in the wild-type strain, due to the dominant negative expression of $HpPOL3^*$. Moreover, after obtaining the desired mutant, the mutator allele was readily removed from the chromosome by homologous recombination to avoid the uncontrolled accumulation of additional mutations. Our mutator system, which depends on the accumulation of random mutations that are incorporated during DNA replication, will be useful to generate strains with mutant phenotypes, especially those related to unknown or multiple genes on the chromosome.

• Journal of Microbiology
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• v.45 no.6
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• pp.558-565
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• 2007

Using microarray analysis, we determined those Salmonella genes induced at the entry of stationary phase, and subsequently discovered that uncharacterized yliH was induced most dramatically. We set out to establish the molecular mechanism underlying the stationary phase induction of yliH under the standard culture condition, LB with vigorous aeration, by analyzing its promoter activity in various mutant backgrounds, lacking stationary phase ${\sigma}$, $RpoS^-$, or stringent signal molecules ppGpp, ${\Delta}relA$ ${\Delta}spoT$. It was found that the stationary phase induction of yliHp was partially dependent on rpoS but entirely dependent on ppGpp. DNA sequence analysis revealed that the Salmonella yliH gene is composed of 381 base-pair nucleotides, with overall amino acid sequence revealing 76.38% amino acid identity and 88.98% similarity with Escherichia coli yliH, although no motif from data base was noted for its possible role. Recently however, it has been reported that yliH in E. coli was implicated in biofilm formation and motility by repressing these activities (Domka et al., 2006). We have constructed a mutant Salmonella deleting yliH gene by allele replacement and examined its phenotype, and found that the yliH in Salmonella more or less affects motility and adherence by enhancing these activities. The effect on biofilm formation in Salmonella was uncertain. Moreover, addition of cloned yliH of E. coli into Salmonella did not reduce motility or adherence. Taken together, it appears that the pathways implicating yliH for biofilm formation and motility in E. coli and in Salmonella are somewhat different.