• Analytical Science and Technology
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• v.11 no.4
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• pp.235-242
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• 1998

Membrane electrode based on chitin(po1y-[$1{\rightarrow}4$]-${\beta}$-N-acetyl-D-glucosamine) was prepared by mixing uniformly grounded of chitin (100 mesh) with PVC and DOS. We investigated the potential response of chitin membrane electrode to metal ions. It was observed that the response slopes for $Cd^{2+}$(34.9 mV/decade) and $Cu^{2+}$(34.0 mV/decade) were larger than those for other ions in pH 4 acetate buffer. The potentiometric response of chitin electrode to varying pH was nearly constant in the pH range of 2~12.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.167-173
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• 2023

Li₃V₂(PO₄)₃ and Li₃V₂(PO₄)₃/C composite with single phase monoclinic structure for the cathode materials are successfully synthesized by direct co-precipitation method using N₂H₄·H₂O as the reducing agent and alginic acid as the carbon source, and their electrochemical properties were compared. The particles with approximately 1~2 ㎛ size and the uniform spherical-like morphology of the narrow particle size distribution were obtained. In addition, the residual carbon can also improve the electrical conductivity. The Li₃V₂(PO₄)₃/C composite has improved initial specific discharge capacity and excellent cycle characteristics to maintain capacity stably than Li₃V₂(PO₄)₃. The results indicate that the reducing agent and carbon composite can affect the good crystallinity and electrochemical performance of the cathode materials.

• Bulletin of the Korean Mathematical Society
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• v.49 no.6
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• pp.1311-1326
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• 2012

We are concerned with the multiplicity of semiclassical solutions of the following Schr$\ddot{o}$dinger system involving critical nonlinearity and magnetic fields $$\{-({\varepsilon}{\nabla}+iA(x))^2u+V(x)u=H_u(u,v)+K(x)|u|^{2*-2}u,\;x{\in}\mathbb{R}^N,\\-({\varepsilon}{\nabla}+iB(x))^2v+V(x)v=H_v(u,v)+K(x)|v|^{2*-2}v,\;x{\in}\mathbb{R}^N,$$ where $2^*=2N/(N-2)$ is the Sobolev critical exponent and $i$ is the imaginary unit. Under proper conditions, we prove the existence and multiplicity of the nontrivial solutions to the perturbed system.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.183-187
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• 2015

We use ALLWISE data release W1- and W2-band epoch photometry collected by the Wide-Field Infrared Survey Explorer (WISE) to determine slopes of the period-luminosity relations for RR Lyrae stars in 15 globular clusters in the corresponding bands. We further combine these results with V- and K-band photometry of Galactic field RR Lyrae stars to determine the metallicity slopes of the log $P_F-[Fe/H]-M_K$, log $P_F-[Fe/H]-M_{W1}$, and log $P_F-[Fe/H]-M_{W2}$ period-metallicity-luminosity relations. We infer the zero points of these relations and determine the kinematical parameters of thick-disk and halo RR Lyraes via statistical parallax, and estimate the RR Lyrae-based distances to 18 Local-Group galaxies including the center of the Milky Way.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.257-261
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• 2008

Previous studies have suggested a possible correlation between cell surface hydrophobicity (CSH) and stress tolerance in Bifidobacterium. In this study, the relationship was examined between CSH and environmental stress tolerance in Lactobacillus spp. By measuring the adhesion to hexadecane, 2 Lactobacillus fermentum strains- KLB 261 and KLB 231 were found to have high and low CSH, respectively. To measure their tolerance to various stresses, cells were subjected to salt (2 M NaCl), acid (pH 2), $H_2O_2$ (0.01 %, v/v), ethanol (20%, v/v), heat ($60^{\circ}C$), and cold ($-20^{\circ}C$). Compared with KLB 231, the hydrophobic KLB 261 was found to be much more resistant to the various stresses examined. After being subjected to different stresses for a period of time, KLB 261 and KLB 231 showed 50 and 0% survivability in 2 M NaCl, 108.2 and 0.6% in 0.01 %(v/v) $H_2O_2$, 40.2%(v/v), and 3.7% at $60^{\circ}C$ incubation, 4 and 0.6% at $-20^{\circ}C$, 12.9 and 0.1 % in pH 2, 33.8 and 0.2% in 20%(v/v) ethanol, respectively. Autoaggregation test and morphological observation were also conducted in an attempt to explain these differences. These results suggested that high CSH could strengthen the stress tolerance of lactobacilli.

• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.414-421
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• 2022

In this study, we isolated Weizmannia ginsengihumi LGHNH (KCTC 14462BP) from 30-year-old wild Panax ginseng C.A. Meyer and elucidated the characteristics of the isolated bacterium and its industrial potential as an anti-aging material. W. ginsengihumi LGHNH was investigated to produce indole-3-acetic acid (IAA), a plant growth-promoting hormone (1.38 ㎍/ml to 2.22 ㎍/ml). We also confirmed the existence of bioconversion activity via the comparison of the ginsenoside content before and after fermentation. As for the converted minor ginsenoside, Rg2(R), Rg4, Rg6, Rg3(S), Rg3(R), Rk1, Rg5, Rh1(R), Rk3 and Rh4 are known to have high bioavailability and various skin effects. We measured mitochondrial membrane potential and ATP biosynthesis to elucidate W. ginsengihumi LGHNH cultured product (WCP) as an anti-aging material. As a result, the mitochondrial membrane potential in HaCaT cells with UVB decreased to 39.3% compared to the unirradiated group, but was recovered to 57.3% and 58.1% by 0.001% (v/v) and 0.01% (v/v) WCP, respectively. In addition, we measured mitochondrial ATP biosynthesis. It decreased to 94.3% compared to the unirradiated group with UVB, but was recovered to 105.3% and 105.7% by 0.001% (v/v) and 0.01% (v/v) WCP.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.834-841
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• 2008

Purpose : This study was perfomed to analyze in detail the viral etiology of acute lower respiratory tract infections (ALRI) in Cheunan, Korea by multiplex RT-PCR, including human rhinovirus (hRV) and newly identified viruses such as human metapneumovirus (hMPV) and human coronavirus (HCoV-OC43, HCoV-229E/NL63). Method : Nasopharyngeal aspirates (NPA) were collected from 863 hospitalized children with ALRI on the first day of admission at Soonchunhyang University Cheonan Hospital and analyzed by multiplex RT-PCR from December 2005 to November 2006. Results : Viral agents were detected from 474 subjects (54.9%). The identified viral pathogens were hRV 9.2%, hMPV 6.8%, HCoV-229E/NL63 1.4%, and HCoV-OC43 2.1%. Coinfections with ${\geq}2$ viruses were observed in 108 patients (22.8%). The major period of viral ALRI was the first year of life. Clinical diagnoses of viral ALRI were pneumonia (59.5%), bronchiolitis (24.7%), tracheobronchitis (11.4%), and croup (4%). The most common causes of bronchiolitis was respiratory syncytial virus B (RSV B), whereas hMPV, hRV, HCoV-229E/NL63, and HCoV-OC43 were commonly found in patients with pneumonia. The number of hMPV infections peaked between March and May 2006. HCoV-OC43 was prevalent from November to February 2006, whereas HCoV-229E and hRV were detected throughout the year. Conclusion : Although the study was confined to one year, hMPV was not detected during winter and peaked between March and April, which was not consistent with previous studies'. This present study indicates that HCoV is a less common respiratory pathogen in cases of ALRI in Korean children

• Journal of the Korean Chemical Society
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• v.26 no.2
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• pp.81-87
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• 1982

The monooxo-bridged binuclear molybdenum(V) complexes, $Mo_2O_3(NCS)_4(Bipy)_2\;(Bipy = bipyridine),\;Mo_2O_3(NCS)-4(Phen)-2$ (Phen = 1,10-phenanthroline), and $Mo_2O_3(NCS)_4(Ox)_2(OxH)_2$ (Ox = oxinato and OxH = oxine) have been prepared. Their electronic and IR spectra, electric conductivity, and magnetic susceptibility were measured. From the results all of th complexes turned out to be electroneutral dimers with about 0.5 BM, and in the oxine complex, $Mo_2O_3(NCS)_2(Ox)_2(OxH)_2$, the oxine seems to bind partly as monodentate and partly as bidentate molecule.

• Economic and Environmental Geology
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• v.34 no.3
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• pp.301-306
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• 2001

Column tests were conducted to investigate the optimal condition of surfactant solution pH that can affect the removal efficiency in surfactant-assisted remediation. Toluene and 1,2,4-trichlorobenzene were chosen as the model hydrophobic substances. Two Iowa soils, Fruitfield sand and Webster clay loam, were leached with solutions of 4%(v/v) sodium diphenyl oxide disulfonate (DOSL, trade name Dowfax 8390), or 4%(v/v) trideceth-19-carboxylic acid (TDCA, trade name Sandopan JA36), or 4% (v/v) octylphenoxypoly ethoxyethanol (OPEE, trade name Triton X100). The test results revealed that a maximum removal of toluene and 1,2,4-trichlorobenzene was obtained at pH 10 of surfactant solution, and maximum recoveries of added toluene (94%) or 1 ,2,4- trichlorobenzene (97 %) were obtained for DOSL surfactant solution in Fruitfield sandy soil column. Increased removal efficiency by pH control of both toluene and 1,2,4trichlorobenzene was 16% and 20% for DOSL with Fruitfild sandy soil, respectively. In addition, the maximum recoveries of added toluene or I ,2,4-trichlorobenzene were 89% and 93% for DOSL surfactant solution in Webster clay loam soil column. The maximum increase of toluene and 1,2,4-trichlorobenzene removal was 26% and 19% for DOSL with Webster clay loam soil, respectively. These experimental results indicate that maintaining a high pH surfactant solution in surfactant-assisted remediation is desirable for efficient removal of NAPLs from contminated soils.

• Journal of the Korean Vacuum Society
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• v.11 no.3
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• pp.151-158
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• 2002

Fabricated were ultra-shallow $p^+-n$ junctions on n-type Si(100) substrates using decaborane $(B_{10}H_{14})$ ion implantation. Decaborane ions were implanted at the acceleration voltages of 5 kV to 10 kV and at the dosages of $1\times10^{12}\textrm{cm}^2$.The implanted specimens were annealed at $800^{\circ}C$, $900^{\circ}C$ and $1000^{\circ}C$ for 10 s in $N_2$ atmosphere through a rapid thermal process. From the measurement of the implantation-induced damages through $2MeV^4 He^{2+}$ channeling spectra, the implanted specimen at the acceleration voltage of 15 kV showed higher backscattering yield than those of the bare n-type Si wafer and the implanted specimens at 5 kV and 10 kV. From the channeling spectra, the calculated thicknesses of amorphous layers induced by the ioin implantation at the acceleration voltages of 5 kV, 10 kV and 15 kV were 1.9 nm, 2.5 nm and 4.3 nm, respectively. After annealing at $800^{\circ}C$ for 10 s in $N_2$ atmosphere, most implantation-induced damages of the specimens implanted at the acceleration voltage of 10 kV were recovered and they exhibited the same channeling yield as the bare Si wafer. In this case, the calculated thickness of the amorphous layer was 0.98 nm. Hall measurements and sheet resistance measurements showed that the dopant activation increased with implantation energy, ion dosage and annealing temperature. From the current-voltage measurement, it is observed that leakage current density is decreased with the increase of annealing temperature and implantation energy.