• Journal of Life Science
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• v.11 no.2
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• pp.120-125
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• 2001

The pyrR gene of the pyrimidine biosynthesis (pyr) operon of the thermophile Bacillus caldolyticus, encoding a uracil phosphoribosyltransferase (UPRTase), turned to rely as a pyr operon regulator. It has been proposed that PyrR mediates transcriptional termination-antitermination at three intercistronic regions of the par operon (S.-Y Ghim and J. Neuhard, J. Bacteriol.,176, 3698-3707, 1994). In this research, a plasmid carrying the pyrR region of B. caldolyticus could restore a pyrimidine regulation in a pyrR mutant of B. subtilis. Expression of pyrR was found to increase 6-7 fold during pyrimidine starvation. Additionally, a highly conserved nucleotide sequence which may constitute the binding site for a PyrR protein (PyrR-binding loop) in transcript was staggested. Alternative antiterminator and terminator structures involving three conserved motifs in front of the pyrR, pyrP and pyrB genes, respectively, are proposed to account for the observed regulation pattern.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.31-38
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• 2006

Quercus mongolica is the most common hardwood species distributed in Korea. This study was conducted to investigate the biomass and energy content of the belowground biomass of Q. mongolica and to obtain the regression equation for estimating root biomass using the tree height and diameter at breast height (DBH). A total of 18 sample trees ranging 20 to 60 year-old were selected in the study sites. Tree height, DBH, age, and weight of stemwood, sapwood, heartwood, stembark, branch, leaf, and root were measured for total biomass. The highly positive correlation was shown between the biomass of most of variables of aboveground components and root biomass. The regression equation of the aboveground total biomass was $log\;W_A\;=\;1.469\;+\;0.992\;log\;D^2H\;(R^2 =0.99)$. The regression equation of the belowground biomass was $log\;W_R\;=\;1.527\;+\;0.808\;log\;D^2H\;(R^2\;=\;0.97)$. The mean energy contents of sapwood, heartwood, bark, leaf, and root were 19,594 J/g DW, 19,571 J/g DW, 19,999 J/g DW, 20,664 J/g DW, and 19,273 J/g DW, respectively. The results obtained from this study can be used to estimate biomass and energy content of belowground using easily measurable variables such as DBH and tree height ranging from 20 to 60-year-old Q. mongolica stands.

• Membrane Journal
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• v.24 no.1
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• pp.39-49
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• 2014

The effects of pH and oxygen back-flushing were investigated in hybrid process of ceramic microfiltration and PES (polyethersulfone) beads loaded with titanium dioxide ($TiO_2$) photocatalyst for advanced drinking water treatment in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As increasing pH, $R_f$ decreased and J increased. Finally the maximum $V_T$ could be acquired at pH 9. Treatment efficiencies of turbidity was almost same independent of pH. Treatment efficiency of dissolved organic matters (DOM) decreased as increasing pH. As results of comparing the oxygen and nitrogen back-flushing, $R_{f,180}$ at oxygen back-flushing was the lower than that at nitrogen back-flushing, and the dimensionless final permeate flux ($J_{180}/J_0$) by initial permeate flux ($J_0$) at oxygen back-flushing was maintained the higher than that at nitrogen back-flushing except 10 and 12 min of back-flushing period (FT). Treatment efficiency of turbidity at oxygen back-flushing was a little higher than that at nitrogen back-flushing. Treatment efficiency of the DOM at nitrogen back-flushing was the higher than that at oxygen back-flushing. Also, treatment efficiency of turbidity at saturated oxygen was similar with those of oxygen and nitrogen back-flushing, but the treatment efficiency of DOM was increased significantly because OH radical could be generated by reaction between saturated oxygen and photocatalyst.

• Journal of the Korean Chemical Society
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• v.8 no.3
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• pp.131-133
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• 1964

• The Academic Congress of Korean Shoulder and Elbow Society
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• 1998.03a
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• pp.41-42
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• 1998

• Bulletin of the Korean Mathematical Society
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• v.41 no.3
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• pp.507-519
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• 2004

For a ring endomorphism $\sigma$ of a ring R, J. Krempa called $\sigma$ a rigid endomorphism if a$\sigma$(a)＝0 implies a＝0 for a ${\in}$R. A ring R is called rigid if there exists a rigid endomorphism of R. In this paper, we extend the (J'-rigid property of a ring R to the upper nilradical $N_{r}$(R) of R. For an endomorphism R and the upper nilradical $N_{r}$(R) of a ring R, we introduce the condition (*): $N_{r}$(R) is a $\sigma$-ideal of R and a$\sigma$(a) ${\in}$ $N_{r}$(R) implies a ${\in}$ $N_{r}$(R) for a ${\in}$ R. We study characterizations of a ring R with an endomorphism $\sigma$ satisfying the condition (*), and we investigate their related properties. The connections between the upper nilradical of R and the upper nilradical of the skew power series ring R[[$\chi$;$\sigma$]] of R are also investigated.ated.

• Nuclear industry
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• v.16 no.7 s.161
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• pp.39-46
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• 1996

• Journal of Animal Science and Technology
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• v.49 no.4
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• pp.437-442
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• 2007

The melanocortin-4 receptor(MC4R) is virtually expressed in all brain regions and plays an important role in energy homeostasis in mammals. MC4R has been intensively studied as a trait gene controlling economically important traits, such as growth and feed conversion, etc. Six hundreds and sixty Duroc pigs were genotyped for the MC4R locus and analyzed their relationships with breeding values for average daily gain(ADG), backfat thickness(BF), days to 90kg(D90) and feed conversion(FC). The estimated genotype frequencies for the all Duroc pigs were: 30.8%, 45.2%, 24.1% for AA, AB and BB genotypes, respectively. The mutant A allele was significantly associated with ADG, D90 and BF whereas no significant relationship was found with FC. The change of gene frequencies by generation was shown in both selected and culled groups. These results indicate that the MC4R polymorphism could be integrated in the present selection program to realize a marker-assisted selection for the growth traits of the Duroc population.

• Proceedings of the Korean Vacuum Society Conference
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• 1993.07a
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• pp.104-105
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• 1993

• 한국약용작물학회:학술대회논문집
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• 2011.04a
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• pp.98-99
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• 2011