• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.73.2-73.2
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• 2019

The physical origin of low escape fractions of ionizing radiation derived from Lyman-break galaxies (LBGs) at z ~ 3 - 4 is a puzzle in the theory of reionization. We perform idealized disk galaxy simulations to investigate how galactic properties, such as metallicity and gas mass, affect the escape of Lyman continuum (LyC) photons using radiation-hydrodynamic code RAMSES-RT, with strong stellar feedback. We find that the luminosity-weighted escape fraction from a metal-poor (Z=0.002) galaxy embedded in a halo of mass M_h ~ 10¹¹ M_⊙ is 〈f^3D_esc〉 ~ 8%. However, when the gas metallicity is increased to Z=0.02, the escape fraction is significantly reduced to 〈f^3D_esc〉 ~ 1%, as young stars are enshrouded by their birth clouds for a longer period of time. On the other hand, increasing the gas mass by a factor of 5 leads to 〈f^3D_esc〉 ~ 4%, as LyC photons are only moderately absorbed by the thicker disk. Our experiments seem to suggest that high metallicity is primarily responsible for the low escape fractions observed from LBGs, supporting the scenario in which the escape fraction has a negative correlation with halo mass. Indeed, our simulated galaxy with the typical metallicity of LBGs (Z=0.006) shows the relative escape fraction of 8%, consistent with recent observations of galaxies with M₁₅₀₀ = -20.

• YAKHAK HOEJI
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• v.43 no.3
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• pp.378-384
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• 1999

Retinoic acid (RA) and dibutyryl cyclic AMP (dbcAMP) induce the differentiation of the multipotent embryonic carcinoma cell line, F9 cells, into parietal endoderm like cell. The F9 cells are highly proliferative doubling approximately 12 hourse. S Phase is predominant, lasting 10 hours and G2/M phase occupies most of the remaining cycle (2 hours) and G1 phase is nearly non-existent. In this study, we showed the effect of RA and dbcAMPon the cell cycle associated molecules (especially around G1 phase) during F9 cell differentiation. Differentiation of F9 cells was induced by the combined addition of RA ($10^{-7}M$) and dbcAMP (0.5mM), and cells were harvested daily up to 4 days. Flow cytometric analysis showed the prolongation of G1 phase around 30 hours after induction. Western blot analysis revealed that the amount of cyclin D1 and cdk2 were increased at day 4. However, histone H1 kinase activity of cdk2 was decreased. These data strongly suggest that RA and dbcAMP induce the growth arrest of F9 cells at G1 phase by decreasing the activity of cdk2, although they have increased the protein contents of cyclin D1 and cdk2. The reason for the discrepancy between the H1 kinase activity and protein contents are not clear yet.

• Bulletin of the Korean Mathematical Society
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• v.55 no.6
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• pp.1859-1868
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• 2018

In the present paper, we have proved the sharp inequality ${\mid}H_{3,1}(f){\mid}{\leq}4$ and ${\mid}H_{3,1}(f){\mid}{\leq}1$ for analytic functions f with $a_n:=f^{(n)}(0)/n!$, $n{\in}{\mathbb{N}},$, such that $$Re\frac{f(z)}{z}>{\alpha},\;z{\in}{\mathbb{D}}:=\{z{\in}{\mathbb{C}}:{\mid}z{\mid}<1\}$$ for ${\alpha}=0$ and ${\alpha}=1/2$, respectively, where $$H_{3,1}(f):=\left|{\array{{\alpha}_1&{\alpha}_2&{\alpha}_3\\{\alpha}_2&{\alpha}_3&{\alpha}_4\\{\alpha}_3&{\alpha}_4&{\alpha}_5}}\right|$$ is the third Hankel determinant.

• Journal of Korean Society of Forest Science
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• v.70 no.1
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• pp.28-37
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• 1985

In order to estimate breast-height form factors of Pinus thunbergii and Cryptomeria japonica, 8 models based on tree age, diameter at breast height and tree height were suggested and evaluated. It was the following equations that turned out to be most fit for estimating them; for Pinus thunbergii, $F=0.553-4.567\;1/A+71.409\;1/A^2$ ($R^2=0.928$), based on tree age, ($6.727^{**}$) ($14.100^{**}$) $F=0.356+1.774\;1/D-0.770\;1/D^2$ ($R^2=0.944$), based on diameter at breast height, ($15.102^{**}$) ($2.908^{**}$) $F=0.316+1.546\;1/H+0.397\;1/H^2$ ($R^2=0.941$), based on tree height, ($8.380^{**}$) ($3.896^{**}$) for Cryptomeria japonica, $F=0.400+2.348\;1/A+17.053\;1/A^2$ ($R^2=0.889$), based on tree age, ($3.501^{**}$) ($3.298^{**}$) $F=0.353+2.118\;1/D-1.462\;1/D^2$ ($R^2=0.923$), based on diameter at breast height, ($14.873^{**}$) ($3.545^{**}$) $F=0.403+0.427\;1/H+2.843\;1/H^2$ ($R^2=0.887$), based on tree height. ($3.254^{**}$) ($5.742^{**}$) The above estimated breast-height form factors proved to be overestimated for young trees and small diameter trees, and to be underestimated for old trees and large diameter trees, in comparison to generally accepted figure in Korea, that is, the form factor of 0.45.

• Archives of Pharmacal Research
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• v.3 no.2
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• pp.87-88
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• 1980

The goal of this research is to provide information that will lead to the development of new non-phototoxic antimalarial compounds. The goal was approached by first learning the chemical mechanism of phototoxicity of six representative compounds 1a-f: a[(diethyl-, -dihexyl-, and -dioctyl- aminomethyl)]-2-(3', 4' -dichlorophenyl)-6-methoxy-4-quinolinemethanol (1a, 1b, and 1c) and .alpha. [(diethyl-, -dibutyl-, and -dihexyl-aminomethyl)]-2-(-4'-methoxyphenyl-6-methoxy-7-chloro-4-quinolinemethan ol (1d, 1e, and 1f). The photochemical reaction of these compounds was investigated in 2-propanol. Similar photochemical fragmentation reactions accurred in all compounds.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.36-40
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• 2011

Purpose: $^{18}F$-FDG injected dose to the patient is quite different between the recommended dose from manufacturer and the actual dose applied to each of hospitals. injection of inappropriate $^{18}F$-FDG dose may not only increase the exposed dose to patients but also reduce the image quality. we thus evaluated the proper $^{18}F$-FDG injected dose to decrease the exposed dose to patients considering the image quality. Materials And Methods: NEMA Nu2-1994 phantom was filled with $^{18}F$-FDG increasing hot cylinder radioactivity concentration to 1, 3, 5, 7, 9 MBq/kg based on the ratio of 4:1 between the hot cylinder and background activity. after completing the transmission scan using ct, emission scan was acquired in 3D mode for 2 minutes 30 seconds/bed. ROI was set up on hot cylinder and background radioactivity region. after measuring $SUV_{max}$ those regions, then analyzed SNR at the points. clinical experiment has been conducted the object of patients who have came to smc from november 2009 to august 2010, 97 patients without having a hepatic lesions were selected. ROI was set up in the liver and thigh area. after measuring $SUV_{max}$, the image quality was compared following the injected dose. Results: in phantom study, as the injected radioactivity concentration per unit mass was 1, 3, 5, 7, 9 MBq/kg, $SUV_{max}$ was 23.1, 24.1, 24.3, 22.8, 23.6 and SNR was shown 0.48, 0.54, 0.56, 0.55, 0.55. according to increment of the injected dose, $SUV_{max}$ and SNR was increased under 5 MBq/kg but they were decreased over 7 MBq/kg. in case of clinical experiment, as increased the injected radioactivity concentration per unit mass was 4.72, 5.34, 6.16, 7.41, 8.68 MBq/kg, $SUV_{max}$ was 2.68, 2.67, 2.26, 1.88, 1.95 and SNR was shown 0.52, 0.53, 0.46, 0.46, 0.44. if the injected dose exceeds 5 MBq/kg, showed a decrease pattern as phantom study. Conclusion: increasing $^{18}F$-FDG injected dose considered patient's body weight improve image quality within a certain range. if it exceeds the range, it can be reduced image quality due to random and scatter coincidences. this study indicates that the optimal injected dose was 5 MBq/kg per unit mass the injected radioactivity concentration in 3d wb pet/ct.

• Korean journal of applied entomology
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• v.31 no.1
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• pp.50-68
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• 1992

The results of survey on the nematodes associated with sapling from 8 Forestry Experiment Stations(F.E.S.) in Korea are reported herein. A total of 35 species under 20 genera, 11 families, and 2 orders were identified from the soils around the roots of 119 tree species and amongst them, Xiphinema insigne is unrecorded species for Korea and Geocenamus sp. is a new species. Tylenchorhynchus claytoni, which showed the highest detection rate (D.R.) from all F.E.S., except Nambu F.E.S, was the dominant species among the nematodes associated with saplings. The D.R. of T. claytoni was the highest in Ch’ungnam F.E.S. by 100% from 15 saplings sampled, followed by 87.5% in Kangwon, 66.6% in Kyongbuk, 58.3% in Cheonbuk, 48.1% in Ch’ungbuk, 41.3% in Kyongki, and 40% in Cheonnam F.E.S. Other important nematode species which showed very high densities by stations are; Criconemella morgensis (D.R.: 37.5%), Helicotylenchus digonicus (D.R. : 35%), Pararotylenchus pini (D.R.: 37%), Tylenchorhynchus nudus (D.R.: 37.9%), Criconemella informis (D.R.: 27.5%), and Meloidogyne sp. (D.R.: 12.5), from Chunbuk, Chunnam, Ch’ungbuk, Kyongki, and Kangwon F.E.S., respectively.

• Korean Journal of Materials Research
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• v.29 no.7
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• pp.451-455
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• 2019

The electromagnetic and thermal properties of a heavy fermion $CeNi_2Ge_2$ are investigated using first-principle methods with local density approximation (LDA) and fully relativistic approaches. The Ce f-bands are located near the Fermi energy $E_F$ and hybridized with the Ni-3d states. This hybridization plays important roles in the characteristics of this material. The fully relativistic approach shows that the 4f states split into $4f_{7/2}$ and $4f_{5/2}$ states due to spin-orbit coupling effects. It can be found that within the LDA calculation, the density of states near the Fermi level are mainly of Ce-derived 4f states. The Ni-derived 3d states have high peaks around -1.7eV and spreaded over wide range around the Fermi level. The calculated magnetic of $CeNi_2Ge_2$ with LDA method does not match with that of experimental result because of strong correlation interaction between electrons in f orbitals. The calculations show that the specific heat coefficient underestimates the experimental value by a factor of 19.1. The discrepancy between the band calculation and experiment for specific heat coefficient is attributed to the formation of a quasiparticle. Because of the volume contraction, the exchange interaction between the f states and the conduction electrons is large in $CeNi_2Ge_2$, which increases the quasiparticle mass. This will result in the enhancement of the specific hear coefficient.

• Natural Product Sciences
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• v.19 no.3
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• pp.258-262
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• 2013

Three ergosterol derivatives, ergosta-4,6,8(14),22-tetraen-3-one (1), ergosta-7,24(28)-dien-3-ol (2), and 5,8-epidioxyergosta-6,22-dien-3-ol(3) were isolated from the fruit body of Phellinus pini. Their structures were based on spectroscopic methods including IR, MS, and NMR (1D and 2D). These compounds were evaluated for their activity to decrease melanin production in ${\alpha}$-MSH (melanocyte stimulating hormone) activated B16F10 cells. Compound 1, 2, and 3 reduced melanin content in a dose-dependent manner at concentrations of 5~15 uM. They also suppressed the tyrosinase expression of protein and m-RNA level dose dependently by western blot analysis and RT-PCR experiment in B16F10 murine melanoma cells.

• Journal of Microbiology and Biotechnology
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• v.9 no.3
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• pp.376-380
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• 1999

Constructs, encoding a single-chain variable fragment of a catalytic antibody 4f4f (scFv-4f4f) with glycosidase activity, were made by combining the coding sequences for the heavy and light chain variable domains with a sequence encoding a linker (GGGGS). Using three different plasmid systems, single-chain antibodies were expressed separately in Escherichia coli, demonstrating significant differences in the expression level and amounts in soluble form of the recombinant protein. The protein expression from pET3a-scFv-4f4f was up to 20% of the total soluble proteins and, more importantly, the proteins were mostly found in a soluble form. An SDS-PAGE analysis of the purified single-chain proteins, yielding higher than 5mg from a 1-1 culture, showed a single band corresponding to its molecular weight of 29,100. A preliminary study shows that the expressed scFv-4f4f is catalytically active. The catalytic parameters for the hydrolysis of p-nitrophenyl-$\beta$-D-glucopyranoside by scFv-4f4f are being investigated.