• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 추계학술대회 논문집
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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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• 제14권2호
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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.

• 천문학회지
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• 제31권2호
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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.

• 생명과학회지
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• 제27권12호
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• pp.1403-1409
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• 2017

본 연구에서는 lignocellulosic biomass (xylose)의 부가가치를 높이고 효율적인 활용을 위해 xylitol dehydrogenase를 Saccharomyces cerevisiae 숙주세포에서 분비 생산하고자 하였다. 먼저 S. cerevisiae와 Pichia stipitis유래 XYL2 유전자(S.XYL2 and P.XYL2 gene)의 발현 시스템을 구축하기 위하여 GAL10 promoter와 ADH1 promoter 하류에 각각 mating factor ${\alpha}$ ($MF{\alpha}$) signal sequence와 XYL2유전자를 가진 $pGMF{\alpha}-S.XYL2$, $pGMF{\alpha}-P.XYL2$, $pAMF{\alpha}-S.XYL2$와 $pAMF{\alpha}-P.XYL2$ plasmid를 구축하였다. 각각의 plasmid는 S. cerevisiae $SEY2102{\Delta}trp1$ 균주에 형질전환되었고, 생산된 xylitol dehydrogenase의 활성을 조사해 본 결과, GAL10 promoter가 ADH1 promoter보다 XYL2유전자의 발현에 더욱 적합함을 확인 할 수 있었다. 또한 P. stipitis 유래의 xylitol dehydrogenase 효소 활성이 S. cerevisiae 유래의 효소 활성보다 2배 이상 더 높았으며, 활성의 증가를 위해 두 유전자 모두 cofactor로 $NAD^+$에 의존한다는 것을 확인하였다. 재조합 유전자가 가지는 분비서열에 의해 $SEY2102{\Delta}trp1/pGMF{\alpha}-P.XYL2$ 균주에서 xylitol dehydrogenase의 약 77%는 periplasmic space로 분비 발현되었음을 알 수 있었다. 또한 재조합 xylitol dehydrogenase의 효율적인 생산을 위해 탄소원의 영향을 조사해본 결과, glucose 단독보다 glucose와 xylose를 혼합 배양한 경우에서 효소활성이 최대 41% 정도 증가되었음을 확인 할 수 있었다. 본 연구에서 최적화한 발현 시스템 및 배양 조건은 xylose 뿐만 아니라 다양한 biomass를 이용한 유용물질 생산을 위한 관련 단백질의 발현 분비시스템 구축 및 대량생산에도 응용될 수 있을 것이라 생각된다.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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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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• 제45권1호
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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.

• 한국음향학회지
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• 제16권5호
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• pp.26-35
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• 1997

본 논문에서는 무중력하에서 자유운동하는 물체의 화상정보로부터 그 운동을 추정할 때의 특징점의 대응점을 선택과 샘플링 주기를 설정하는 방법을 제안하였다. 관성 좌표계를 우주 로봇에 내장된 카메라 좌표계로 치환하여 화상에서 구해진 정보로부터 대응점 문제를 해석하고, 대상 물체의 운동을 결정하는 각속도 vector $\omega$를 구하는 것이 가능하다는 것을 시뮬레이션에 의하여 조사하였다. 또한, 특징점의 운동거리에 대한 상대오차가 양자화에 의해서 증가하기 때문에 샘플링 주기 ${\Delta}t$가 짧으면 각속도의 상대오차는 증가한다. 역으로 샘플링 주기 ${\Delta}t$가 너무 길어져도 각속도가 근사화될 때 샘를링 주기가 길기 때문에 오차가 증가한다. 한편, 정밀도는 해상도가 증가함에 따라 증가한다는 것을 확인하였다.

• 천문학회지
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• 제18권2호
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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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• 제23권3호
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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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• 제45권6호
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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.