• Korean Journal of Materials Research
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• v.26 no.2
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• pp.73-78
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• 2016

$TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

• Molecules and Cells
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• v.21 no.1
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• pp.63-75
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• 2006

The 5′-region of Potato virus X (PVX) RNA, which contains an AC-rich, single-stranded region and stem-loop structure 1 (SL1), affects RNA replication and assembly. Using Systemic Evolution of Ligands by EXponential enrichment (SELEX) and the electrophoretic mobility shift assay, we demonstrate that SL1 interacts specifically with tobacco protoplast protein extracts (S100). The 36 nucleotides that correspond to the top region of SL1, which comprises stem C, loop C, stem D, and the tetra loop (TL), were randomized and bound to the S100. Remarkably, the wild-type (wt) sequence was selected in the second round, and the number of wt sequences increased as selection proceeded. All of the selected clones from the fifth round contained the wt sequence. Secondary structure predictions (mFOLD) of the recovered sequences revealed relatively stable stem-loop structures that resembled SL1, although the nucleotide sequences therein were different. Moreover, many of the clones selected in the fourth round conserved the TL and C-C mismatch, which suggests the importance of these elements in host protein binding. The SELEX clone that closely resembled the wt SL1 structure with the TL and C-C mismatch was able to replicate and cause systemic symptoms in plants, while most of the other winners replicated poorly only on inoculated leaves. The RNA replication level on protoplasts was also similarly affected. Taken together, these results indicate that the SL1 of PVX interacts with host protein(s) that play important roles related to virus replication.

• Molecules and Cells
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• v.28 no.5
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• pp.463-472
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• 2009

Although the possible cellular roles of several ubiquitin-specific proteases (UBPs) were identified in Arabidopsis, almost nothing is known about UBP homologs in rice, a monocot model plant. In this report, we searched the rice genome database (http://signal.salk.edu/cgi-bin/RiceGE) and identified 21 putative UBP family members (OsUBPs) in the rice genome. These OsUBP genes each contain a ubiquitin carboxyl-terminal hydrolase (UCH) domain with highly conserved Cys and His boxes and were subdivided into 9 groups based on their sequence identities and domain structures. RT-PCR analysis indicated that rice OsUBP genes are expressed at varying degrees in different rice tissues. We isolated a full-length cDNA clone for OsUBP6, which possesses not only a UCH domain, but also an N-terminal ubiquitin motif. Bacterially expressed OsUBP6 was capable of dismantling K48-linked tetra-ubiquitin chains in vitro. Quantitative real-time RT-PCR indicated that OsUBP6 is constitutively expressed in different tissues of rice plants. An in vivo targeting experiment showed that OsUBP6 is predominantly localized to the nucleus in onion epidermal cells. We also examined how knock-out of OsUBP6 affects developmental growth of rice plants. Although homozygous T3 osubp6 T-DNA insertion mutant seedlings displayed slower growth relative to wild type seedlings, mature mutant plants appeared to be normal. These results raise the possibility that loss of OsUBP6 is functionally compensated for by an as-yet unknown OsUBP homolog during later stages of development in rice plants.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.5
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• pp.2103-2123
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• 2018

Ships built today are larger in scale and feature more complex structures. The ever-evolving systems used on board a ship require vast amounts of data processing. In the future, with the advent of smart ships, unmanned ships and other next-generation ships, the volumes of data to be processed will continue to increase. Yet, to date, ship data has been processed using wired networks. Placed at fixed locations, the nodes on wired networks often fail to process data from mobile devices. Despite many attempts made to use Wi-Fi on ships just as on land to create wireless networks, Wi-Fi has hardly been available due to the complex metal structures of ships. Therefore, Wi-Fi on ships has been patchy as the ship-wide total Wi-Fi coverage has not properly implemented. A new ship-wide wireless network environment is part of the technology conducive to the shipbuilding industry. The wireless network environment should not only serve the purpose of communication but also be able to manage and control multiple features in real-time: fault diagnostics, tracking, accident prevention and safety management. To better understand the characteristics of wireless frequencies for ships, this paper tests the widely used TETRA, UHF and Wi-Fi and sheds light on the features, advantages and disadvantages of each technology in ship settings. The proposed deployment of a Super Wi-Fi network leveraging the legacy UHF system of TMS generates a ship-wide wireless network environment. The experimental findings corroborate the feasibility of the proposed ship-wide Super Wi-Fi network environment.

• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.46-50
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• 1996

Monoanionic nickel(Ⅲ) complexes, [Ni(dmbit)2]1- and [Ni(dmbbip)2]1- where dmbit2- and dmbbip2- denote 2-thiobenzo[d]-1,3-dithiole-5,6-dithiolate and 1,2-bis(isopropylthio)benzen-4,5-dithiolate, respectively, have been synthesized by the iodine oxidation of dianionic complexes. In the scanning electron microscopic(SEM) images, these complexes show the well-grown two-dimensional layered structures which are clearly comparable to the dianionic ones with three-dimensional structures. Magnetic susceptibilities of nickel(Ⅲ)complexes are fitted well with the two-dimensional Heisenberg antiferromagnet model of S=1/2 system resulting in the spin-exchange parameters (|J|/k) of 11.4 K and 0.45 K, respectively. The weaker magnetic interaction in [Ni(dmbbip)2]1- is resulted from the bulky isopropyl groups on the periphery of dmbbip ligand. EPR measurements for [Ni(dmbit)2]1- give the signal with axial symmetry and the anisotropic g-values for low-spin nickel(Ⅲ) (g//=2.158, g =2.030,gav=2.074 at 300 K; g//=2.162, g =2.038, gav=2.080 at 77 K). It is therefore concluded that nickel(Ⅱ) is oxidized to nickel(Ⅲ), rather than dmbit2- and dmbbip2- ligands are, by the iodine oxidation. The paramagnetic Ni(Ⅲ) would be located in the axial symmetry(D4h) with the electronic configuration of (dxz2dyz2dz22dxy1dx2-y20).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.552-560
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• 2021

This study investigated anti-inflammatory and antibacterial activities of Sedum takesimense ethanolic extract, and 3 isolated compounds. To confirm anti-inflammatory and anti-acne activities, a nitric oxide (NO) inhibition assay, pro-inflammatory factor (TNF-α, IL-1β, and IL-8) inhibition assays, and minimum inhibitory concentration (MIC) tests were performed. The 3 isolated compounds were identified as 4,6-di-O-galloylarbutin (OGA), 2,4,6-tri-O-galloyl-glucose (OGG), and 1,2,4,6-tetra-O-galloyl-β-glucose (TOGG). The ethanolic extract and isolated compounds (OGA, OGG, TOGG) effectively inhibited production of NO and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-8). Furthermore, OGG and TOGG exhibited MIC values toward Cutibacterium acnes of 12.5 ㎍/mL and 3.2 ㎍/mL, respectively. These results suggest that S. takesimense extract exerts an anti-inflammatory effect on LPS-induced RAW264.7 cells, and an antibacterial efficacy against C. acnes.

• The Korea Journal of Herbology
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• v.36 no.3
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• pp.39-46
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• 2021

Objectives : Mangifera indica leaves are well known for having a variety of benefits, including anti-inflammatory, anti-tumor, diabetic retinopathy and diabetic vasculosis. However, the effects of Mangifera indica leaves on hair loss inhibition have not been studied. In this study, we investigated to find out the activity of Mangifera indica leaves on hair loss. Methods : 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid(ABTS) analysis was performed to confirm the antioxidant efficacy of the water extract of Mangifera indica leaves (WEML). To examine the effect of WEML on cell viability in dermal papillar (DP) cells, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra Zolium (MTS) analysis was performed. The changes in the mRNA expression level of the hair loss and hair growth-related genes in dermal papilla cells by WEML treatment were confirmed by quantitative RT-PCR. Results : In dermal papilla (DP) cells, ABTS analysis and MTS analysis of WEML showed antioxidant efficacy and low cytotoxicity. As a result of gene expression analysis through Quantitative RT-PCR, no changes in hair growth-related genes BMP6 and CTNNB1 was confirmed. but inhibitory activity of WEML on hair loss-related genes EGR1, SGK, DKK1, SRD5A1 and SRD5A2 was confirmed. Conclusion : We confirmed that WEML has excellent antioxidant efficacy and a inhibitory activity of hair loss-related genes including 5α-reductase genes. These results suggest that Mangifera indica leaves have a potential activity as a hair loss treatment for hair loss and hair growth. Biochemical or molecular biological research on hair loss is needed.

• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.267-273
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• 2021

Camellia nut shell was collected, dried at room temperature and ground to get fine powder. The powder was extracted three times with 95% EtOH, combined, evaporated, and then freeze dried. The crude powder was dissolved in H₂O and then sequentially fractionated with n-hexane, CH₂Cl₂, EtOAc and n-BuOH. A part of EtOAc fraction was chromatographed on a silica gel and on a Sephadex LH-20 columns using MeOH, aqueous MeOH, EtOAc-n-hexane and EtOH-n-hexane to isolate gallotannins. Three gallotannins, 1,2-di-O-galloyl-β-D-glucopyranoside (2), 1,2,6-tri-O-galloyl-β-D-glucopyranoside (3) and 1,2,3,6-tetra-O-galloyl-β-D-glucopyranoside (4), including gallic acid (1), were isolated and elucidated by NMR and Mass spectroscopies. Although nothing new, these gallotannins were first reported from the nut shell extractives of camellia tree (Camellia oleifera C. Abel). This study was to investigate the chemical constituents, especially hydrolysable tannins, of nut shell extractives of Camellia oleifera and to provide basic information for the future chemical utilization of this species.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.109-118
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• 2018

Two-row overlap pile wall, currently under development for use in deep excavations, is a novel retaining structure designed to perform itself as a cutoff wall as well as a high-stiffness wall by constructing four overlapping piles arranged in zigzag manner at a time using a tetra-axis auger. This wall has a relatively complex cross-section, compared with other types of pile wall, which would make it difficult to determine design parameters related to cross-section. In this study, a flexural rigidity equation has been derived by analyzing both theoretically and statistically various wall cross-sections with different pile diameters and overlap lengths. The flexural rigidity equation was found to show the maximum error rate of 3%.

• Tribology and Lubricants
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• v.35 no.2
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• pp.87-93
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• 2019

This work aims to develop a dry lubricant for oilless bush, especially a solid lubricant, thereby creating a coating method with improved properties of anti-friction and load-carrying capacity without oil lubrication. In this work, spherical-shaped powders of thermosetting resin such as polyimide (PI) are mixed with a binder matrix obtained by mixing a fluorocarbon compound resin such as Polytetrafluoroethylene (PTFE) or Ethylene tetra fluoro ethylene (ETFE) with itself or with a non-fluorocarbon thermoplastic resin such as Polyether ether ketone (PEEK). And these dry lubricant mixtures are thickly coated (200-300 mm in the thickness) on the inner surface of the bush by using a wet-typed air-spray deposition method. It was found that the load-carrying capacity of the solid lubricant for excavator bush (60 mm in diameter) that operates under a high load condition (at 40 MPa) is greatly improved owing to the spherical-shaped powders of thermosetting resin. In addition, the coefficient of friction at the sliding surface is also reduced less than 0.1. Thick coating also lowers the contact stress at the edge of a bush that results in better tribological performances. The result suggests that the lubrication performance and durability life of the bush can be remarkably improved even without lubrication (oil or grease).