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Chungnam National University is one of ten Flagship Korean National Universities. It is recognized as one of the most prestigious five national universities in Korea. Wikipedia.

You Y.,Chungnam National University
The American journal of emergency medicine | Year: 2012

Intravenous fat emulsion (IFE) therapy is an adjunct therapy administered to hemodynamically compromised patients with glyphosate-surfactant intoxication when they respond poorly to conventional therapies such as fluid resuscitation or vasopressors [1,2]. However, the use of IFE as an adjunct therapy in collapsed patients with glyphosate intoxication has not been reported previously. Here, we describe the case of a patient with glyphosate-surfactant-induced cardiovascular collapse who responded to IFE. Source

Bae J.,Chungnam National University | Kim S.,University of Seoul
Queueing Systems | Year: 2010

We consider a G/M/1 queue in which the patience time of the customers is constant. The stationary distribution of the workload of the server, or the virtual waiting time, is derived by the level crossing argument. To this end, we obtain the expected downcrossings of a level in the workload process during a busy cycle and then the expected length of a busy cycle. For both the expectations, we use the dual property between the M/G/1 and G/M/1 queue. © 2010 Springer Science+Business Media, LLC. Source

Kyung E.-J.,Chungnam National University | Ryu J.-H.,St Marys Hospital | Kim E.-Y.,Chung - Ang University
British Journal of Radiology | Year: 2013

Objective: To determine and analyse the characteristics of contrast media adverse reactions (CM-ARs) reported in a hospital. Methods: A retrospective review of CM-ARs from the electronic spontaneous adverse drug reaction (ADR) report system between January 2011 and August 2012 was conducted. CM-ARs were evaluated in terms of causality, severity, preventability and affected organs. Also, agreement and correlation among the tools used to evaluate CM-ARswere analysed. Results: The overall reaction rate was 1.5% (n=286). In total, 269 CM-ARs were identified. For ADR causality, 96.7% (n=260) and 98.5% (n=265) were evaluated as "probable" ADR using the Naranjo probability scale and the World Health Organization-Uppsala Monitoring Centre causality categories, whereas 98.1% (n=264) were evaluated as "certain" with Korean algorithm v. 2. Of these, 91.4% (n=246) were mild in severity and 96.7% (n=260) were unpreventable. Most patients (n=233, 86.7%) could be managed with observation and/or simple treatment. The most frequent reaction (n=383, 79.5%) was dermatological. Spearman's correlation coefficient was 0.667 (p<0.01), and the agreement was 98.1% between the Naranjo scale and the World Health Organization-Uppsala Monitoring Centre categories. No relationship was seen between CM-AR severity and gender or between in- and outpatients. Conclusion: In our study, most CM-ARs were mild and managed with simple treatment. However, as the number of patients undergoing CT procedures continues to increase, it is essential to identify and observe patients at risk for CM-ARs to prevent severe ADRs. Advances in knowledge: Continuous careful review of reporting and treatment protocols of CM-ARs is needed to prevent morbidity and mortality. © 2013 The Authors. Published by the British Institute of Radiology. Source

Bianchi L.,Johns Hopkins University | Efremova B.,Sigma Space Corporation | Hodge P.,University of Washington | Kang Y.,Johns Hopkins University | Kang Y.,Chungnam National University
Astronomical Journal | Year: 2012

We studied the young stellar populations of 22 star-forming regions in the Andromeda galaxy (M31), with Hubble Space Telescope (HST) multi-band imaging from far-UV to I. The regions were selected from Galaxy Evolution Explorer (GALEX) wide-field far-UV imaging; they sample different environments and galactocentric distances from 6 to 22kpc. They were imaged with 30 HST fields (360 distinct images, in six bandpasses), with a pixel scale of 0.38pc projected on the sky, at the distance of M31. This study is part of HST treasury survey program HST-GO-11079, which includes star-forming regions in eight Local Group galaxies. We provide a merged catalog of six-band stellar photometry in the 30 M31 fields, containing 118,036 sources brighter than V and B ∼ 23mag. Each HST field covers about 0.3kpc 2 in M31, and contains up to ∼7000 stars, of which the number varies by a factor of >7 among the target regions; a large fraction of the sample are hot massive stars, due to our choice of filters and exposures. We derived stellar physical parameters and interstellar extinction for individual sources by spectral energy distribution analysis with model-atmosphere colors, and used the results to infer ages, massive stars content, and extinction of the star-forming regions. Reddening is up to E(B - V) ≲ 0.6mag in some OB associations, and lowest in the outermost regions (average of ≲0.12mag in OB184 at 21.9kpc). We examined the spatial distribution (clustering) of the hot massive stars, and defined OB associations on various spatial scales from compact to wider, more spread out ones. A hierarchical structuring is observed, with small compact groups arranged within large complexes. Their areas vary from less than 10 to 10 5pc 2, and masses are up to 10 5 M ⊙, in the scales sampled by our analysis. Their cumulative mass distribution follows a power law, at least in part of the sampled regime. Hot-star counts in the young regions compare very well with integrated measurements of UV flux from GALEX. © 2012. The American Astronomical Society. All rights reserved. Source

Kim M.Y.,Chungnam National University
Journal of medicinal food | Year: 2010

The beneficial effect of Spirulina (Spirulina platensis) on tissue lipid peroxidation and oxidative DNA damage was tested in the hypercholesterolemic New Zealand White rabbit model. After hypercholesterolemia was induced by feeding a high cholesterol (0.5%) diet (HCD) for 4 weeks, then HCD supplemented with 1% or 5% Spirulina (SP1 or SP5, respectively) was provided for an additional 8 weeks. Spirulina supplementation significantly reduced the increased lipid peroxidation level in HCD-fed rabbits, and levels recovered to control values. Oxidative stress biomarkers such as glutathione, glutathione peroxidase, glutathione reductase, and glutathione S-transferase were significantly improved in the liver and red blood cells of rabbits fed SP1. Furthermore, SP5 induced antioxidant enzyme activity by 3.1-fold for glutathione, 2.5-fold for glutathione peroxidase, 2.7-fold for glutathione reductase, and 2.3-fold for glutathione S-transferase in liver, compared to the HCD group. DNA damage in lymphocytes was significantly reduced in both the SP1 and SP5 groups, based on the comet assay. Findings from the present study suggest that dietary supplementation with Spirulina may be useful to protect the cells from lipid peroxidation and oxidative DNA damage. Source

E-cadherin and β-catenin are molecules that mediate cell-cell adhesion in normal epithelium. Aberrant expression of these adhesion molecules results in the loss of intercellular adhesion, with possible cell transformation and tumour progression. We determined the role of E-cadherin and β-catenin in the pathogenesis of sinonasal inverted papilloma (IP) and its malignant transformation. We determined the expression of E-cadherin and β-catenin by immunohistochemistry in paraffin-embedded tissue of 21 subjects with nasal polyps, 56 with IPs, 7 IPs with dysplasia and 18 IPs with squamous cell carcinoma (SCC). The clinicopathological variables of the IPs with SCC correlated with the degree of expression of E-cadherin and β-catenin. The degree of expression of E-cadherin and β-catenin in the cell membrane was significantly lower in IPs with SCC than in nasal polyps and IPs. The degree of expression of β-catenin was significantly lower in IPs with SCC with a malignant proportion > 50% compared to a malignant proportion ≤ 50%. However, there was no significant association between the degree of expression of E-cadherin and β-catenin and clinicopathological variables, such as age, gender, T stage, tumour differentiation, or SCC type (metachronous vs. synchronous). In addition, there was no significant relationship between recurrence or survival rate in IPs with SCC and the degree of expression of E-cadherin or β-catenin in the cell membrane or nuclear β-catenin. Decreased expression of E-cadherin and β-catenin in the cell membrane may be associated with carcinogenesis of IPs and help predict malignant transformation in sinonasal IPs. Source

Yoo C.S.,Ulsan National Institute of Science and Technology | Luo Z.,University of Connecticut | Lu T.,University of Connecticut | Kim H.,Chungnam National University | Chen J.H.,Sandia National Laboratories
Proceedings of the Combustion Institute | Year: 2013

The effect of thermal stratification, spark-ignition, and turbulence on the ignition of a lean homogeneous iso-octane/air mixture at constant volume and high pressure is investigated by direct numerical simulations (DNS) with a new 99-species reduced kinetic mechanism developed for very lean mixtures from a detailed mechanism. Two-dimensional DNS are performed in a fixed volume with two-dimensional isotropic velocity spectrums, temperature fluctuations, and an ignition source superimposed on the initial scalar fields. The influence of variations in the initial temperature field imposed by changing the variance of temperature, the ignition-timing by changing the time at which the ignition source is superimposed, and the turbulence intensity and length scale on ignition of a lean iso-octane/air mixture is elucidated. The mean heat release rate increases more slowly and ignition delay decreases with increasing thermal stratification under homogeneous charge compression-ignition (HCCI) conditions since the present mean temperature lies far outside of the negative temperature coefficient (NTC) regime. The spark-ignition induces relatively short ignition delay under spark-assisted compression ignition (SACI) conditions while mildly spreading out the mean heat release rate. For SACI combustion, high turbulence intensity decreases the ignition delay more by increasing the turbulent flame area. Displacement speed and Damköhler number analyses reveal that the high degree of thermal stratification induces deflagration at the reaction fronts, and hence, the mean heat release rate is smoother subsequent to thermal runaway occurring at the highest temperature regions in the domain. For SACI combustion, the heat release rate occurs solely by deflagration prior to the occurrence of the maximum heat release rate and subsequently by mixed modes of deflagration and spontaneous ignition. These results suggest that thermal stratification provides smooth operation of HCCI engines and moreover, spark-ignition can precisely control the ignition timing for SACI combustion. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Source

Cha S.M.,Chungnam National University
Journal of Pediatric Orthopaedics Part B | Year: 2015

Solitary osteochondromas originating from the carpal bones are very uncommon; when they occur, they usually arise from the scaphoid or capitate. We report a solitary, unilobed osteochondroma arising from the hamate that was excised, with no evidence of recurrence at the 3-year follow-up. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. Source

Lee J.H.,Chungnam National University | Noh G.,Pyeongtaek International Hospital
Cytokine | Year: 2013

Background: AD patients exhibit sensitisation to multiple allergens due to a Th1/Th2 imbalance. Until now, it was impossible to improve the polysensitised status and elevated serum total IgE levels. In this study, the effects of IFN-gamma on systemic polysensitisation to multiple allergens and on serum total IgE levels are investigated. Methods: A total of 44 AD patients whose food allergies were completely controlled and who were polysensitised to multiple allergens according to the SPT were selected. Twenty-two of these patients received IFN-gamma therapy twice a week for 2. months, and 22 patients did not receive this therapy. The blood eosinophil % and serum total IgE levels were assessed, and a skin prick test for 51 allergens was performed before and after the IFN-gamma therapy. Results: With IFN-gamma therapy, the polysensitisation status was improved, as demonstrated by a decrease in the positive allergen count and skin reactivity (systemic polydesensitisation). The improvement in the polysensitised status was accompanied by a decrease in serum total IgE levels. The change in serum total IgE levels was significantly correlated with the change in polysensitisation status. Conclusions: IFN-gamma therapy resulted in systemic polydesensitisation with reduced levels of serum total IgE. IFN-gamma is indicated in AD patients with high serum total IgE levels whose food allergies are well controlled and who are polysensitised to multiple allergens. © 2013 Elsevier Ltd. Source

Lee G.,Chungnam National University | Kim J.-C.,Korea Institute of Water and Environment
Journal of Hydrologic Engineering | Year: 2010

Identifying the optimal drainage network based on digital elevation models (DEMs) is a fundamental task in rainfall-runoff modeling. Rapidly improving geographic information system technology enables hydrologists to use a variety of DEM-based hydrologic models that yield spatially concrete outputs. However, reliable drainage networks are still difficult to represent due to insufficient information about the dynamic behavior of water movement on catchment hillslopes. This study proposes an efficient method for drainage network identification through a comparative analysis of geomorphologic characteristics, such as drainage density, length of hillslope flow path, source area, etc., using area threshold and slope-area threshold criteria that incorporate scaling properties between the local slope and the contributing area. The results demonstrate that both criteria yield different drainage networks from "blue lines" based on topographic map from the Korean National Geographic Information Institute. Although the drainage networks obtained from the two criteria are visually similar, the area threshold yields an incorrect drainage structure due to excessive constraint of the draining source area size. In contrast, use of the slope-area threshold produces a relatively acceptable drainage structure in terms of preserving constant geomorphologic similarity to the study catchment. The proposed drainage network identification procedure may be used to describe landscape evolution for channel initiation in catchment hydrology. In addition, the comparative analysis of geomorphologic characteristics is found to provide important preprocess information for selecting a threshold value to generate reliable drainage networks based on DEMs before the application of hydrologic models. © 2011 ASCE. Source

Choi S.,Chungnam National University | Ong D.S.T.,Scripps Research Institute | Kelly J.W.,Scripps Research Institute
Journal of the American Chemical Society | Year: 2010

We describe a non-fluorescent, second generation stilbene that very selectively binds to transthyretin in complex biological environments and remains dark until it chemoselectively reacts with the pKa-perturbed Lys-15 ε-amino group of transthyretin to form a bright blue fluorescent conjugate. Stilbene A2 is mechanistically unusual in that it remains non-fluorescent in cell lysates lacking transthyretin, even though there is likely some proteome binding. Thus, it is especially useful for cellular imaging, as background fluorescence is undetectable until A2 reacts with transthyretin. The mechanistic basis for the effective lack of environment-sensitive fluorescence of A2 when bound to, but before reacting with, transthyretin is reported. Stilbene A2 exhibits sufficiently rapid transthyretin conjugation kinetics at 37 °C to enable pulse-chase experiments to be performed, in this case demonstrating that transthyretin is secreted from HeLa cells. As the chase compound, we employed C1, a cell-permeable, highly selective, non-covalent, transthyretin-binding dihydrostilbene that cannot become fluorescent. The progress reported is viewed as a first and necessary step toward our long-term goal of creating a one-chain, one-binding-site transthyretin tag, whose fluorescence can be regulated by adding A2 or an analogous molecule. Fusing proteins of interest to a one-chain, one-binding-site transthyretin tag regulated by A2 should be useful for studying folding, trafficking, and degradation in the cellular secretory pathway, utilizing pulse-chase experiments. Immediate applications of A2 include utilizing its conjugate fluorescence to quantify transthyretin concentration in human plasma, reflecting nutritional status, and determining the binding stoichiometry of kinetic stabilizer drugs to transthyretin in plasma. © 2010 American Chemical Society. Source

Byun E.-H.,Kyushu University | Byun E.-H.,Chungnam National University | Omura T.,Kyushu University | Yamada K.,Kyushu University | Tachibana H.,Kyushu University
FEBS Letters | Year: 2011

Here we show the molecular basis for the inhibition of peptidoglycan (PGN)-induced TLR2 signaling by a major green tea polyphenol epigallocatechin-3-gallate (EGCG). Recently, we identified the 67-kDa laminin receptor (67LR) as the cell-surface EGCG receptor. Anti-67LR antibody treatment or silencing of 67LR resulted in abrogation of the inhibitory action of EGCG on PGN-induced production of pro-inflammatory mediators and activation of mitogen-activated protein kinases. Silencing of Toll-interacting protein (Tollip), a negative regulator of TLR signaling impaired the TLR2 signaling inhibitory activity of EGCG, suggesting that TLR2 response could be inhibited by EGCG via 67LR and Tollip. © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved. Source

Lee G.,National Assembly Research Service | Yu W.,Kyoto University | Jung K.,Chungnam National University
Environmental Earth Sciences | Year: 2013

Increasing rainfall intensity and frequency due to extreme climate change and haphazard land development are aggravating soil erosion problems in Korea. A quantitative estimate of the amount of sediment from the catchment is essential for soil and water conservation planning and management. Essential to catchment-scale soil erosion modeling is the ability to represent the fluvial transport system associated with the processes of detachment, transport, and deposition of soil particles due to rainfall and surface flow. This study applied a spatially distributed hydrologic model of rainfall-runoff-sediment yield simulation for flood events due to typhoons and then assessed the impact of topographic and climatic factors on erosion and deposition at a catchment scale. Measured versus predicted values of runoff and sediment discharge were acceptable in terms of applied model performance measures despite underestimation of simulated sediment loads near peak concentrations. Erosion occurred widely throughout the catchment, whereas deposition appeared near the channel network grid cells with a short hillslope flow path distance and gentle slope; the critical values of both topographic factors, providing only deposition, were observed at 3.5 (km) (hillslope flow path distance) and 0.2 (m/m) (local slope), respectively. In addition, spatially heterogeneous rainfall intensity, dependent on Thiessen polygons, led to spatially distinct net-erosion patterns; erosion increased gradually as rainfall amount increased, whereas deposition responded irregularly to variations in rainfall. © 2012 Springer-Verlag Berlin Heidelberg. Source

Jang Y.-C.,Chungnam National University
Journal of Material Cycles and Waste Management | Year: 2010

In Korea, generation of waste electrical and electronic equipment (WEEE), or electronic waste (e-waste), has rapidly increased in recent years. The management of WEEE has become a major issue of concern for solid waste communities due to the volumes of waste being generated and the potential environmental impacts associated with the toxic chemicals found in most electronic devices. Special attention must be paid when dealing with WEEE because of toxic materials that it contains (e. g., heavy metals, polybrominated diphenyl ethers, phthalates, and polyvinyl chloride). If managed improperly, the disposal of WEEE can adversely affect the environment and human health. Environmental regulatory agencies; electronic equipment manufacturers, retailers, and recyclers; environmental nongovernmental organizations; and many others are much interested in updated statistics with regard to how much WEEE is generated, stored, recycled, and disposed of. In Korea, an extended producer responsibility policy was introduced in 2003 not only to reduce the amount of electronic products requiring disposal, but also to promote resource recovery from WEEE; the policy currently applies to a total of ten electrical and electronic product categories. This article presents an overview of the current recycling practices and management of electrical and electronic waste in Korea. Specifically, the generation rates, recycling systems and processes, and recent regulations of WEEE are discussed. We estimated that 1 263 000 refrigerators, 701 000 washing machines, 1 181 000 televisions, and 109 000 airconditioning units were retired and handled by the WEEE management system in 2006. More than 40% of the products were collected and recycled by producers. Four major producers' recycling centers and other WEEE recycling facilities are currently in operation, and these process a large faction of WEEE for the recovery of valuable materials. Much attention should still be paid to pollution prevention and resource conservation with respect to WEEE. Several suggestions are made in order to deal with electronic waste management problems effectively and to prevent potential impacts. © 2010 Springer Japan. Source

Noh H.-B.,Pusan National University | Rahman M.A.,Chungnam National University | Yang J.E.,Pusan National University | Shim Y.-B.,Pusan National University
Biosensors and Bioelectronics | Year: 2011

An ultrasensitive electrochemical immunosensor for a protein using a Ag (I)-cysteamine complex (Ag-Cys) as a label was fabricated. The low detection of a protein was based on the electrochemical stripping of Ag from the adsorbed Ag-Cys complex on the gold nanoparticles (AuNPs) conjugated human immunoglobulin G (anti-IgG) antibody (AuNPs-anti-IgG). The electrochemical immunosensor was fabricated by immobilizing anti-IgG antibody on a poly-5,2':5',2''-terthiophene-3'-carboxylic acid (polyTTCA) film grown on the glassy carbon electrode through the covalent bond formation between amine groups of anti-IgG and carboxylic acid groups of polyTTCA. The target protein, IgG was sandwiched between the anti-IgG antibody that covalently attached onto the polyTTCA layer and AuNPs-anti-IgG. Using square wave voltammetry, well defined Ag stripping voltammograms were obtained for the each target concentration. Various experimental parameters were optimized and interference effects from other proteins were checked out. The immunosensor exhibited a wide dynamic range with the detection limit of 0.4 ± 0.05. fg/mL. To evaluate the analytical reliability, the proposed immunosensor was applied to human IgG spiked serum samples and acceptable results were obtained indicating that the method can be readily extended to other bioaffinity assays of clinical or environmental significance. © 2011 Elsevier B.V. Source

Kim S.-J.,Chungnam National University
International Journal of Applied Engineering Research | Year: 2015

According to Cisco, global mobile data traffic will increase nearly 11-fold between 2013 and 2018. Mobile video traffic will reach 75% by 2018 from 66% in 2013 in Korea. As LTE provides high-speed service, the role of mobile phones seems to change from voice to data service. However, voice service is still the most important role of mobile phones. Thus, controllability of throughput and low BLER is indispensable for high-quality VoIP service among various type of traffic. Although the maximum AMR-WB, 23.85 Kbps is sufficient to a VoIP call, it is difficult for the LTE that can provide tens to hundreds of MB/s may not keep the certain level VoIP QoS especially in the cell-edge area. This paper proposes a new scheduling algorithm in order to improve VoIP performance. The proposal is the technology that applies more priority processing for VoIP than other applications in cell-edge area based on two-tier scheduling algorithm. The simulation result shows the improvement of VoIP performance in the viewpoint of throughput and BLER. © Research India Publications. Source

Choi S.,Chungnam National University | Kelly J.W.,Scripps Research Institute
Bioorganic and Medicinal Chemistry | Year: 2011

Herein we demonstrate that competition between candidate kinetic stabilizer binding to transthyretin (TTR) and stilbene binding to and reaction with the same thyroxine sites within TTR can be utilized to discover potent and highly selective non-covalent TTR amyloidogenesis inhibitors. We report two stilbenes, S1 and S2, for use in distinct competition assays. Each bind selectively to TTR and then chemoselectively react to form an amide bond with the Lys-15 residue of TTR, creating a fluorescent conjugate. We used 28 TTR kinetic stabilizers exhibiting a known spectrum of plasma TTR binding selectivities and TTR amyloid fibril inhibition efficacies to validate the 'TTR fluorescence conjugate competition assay'. The kinetic stabilizers competed with S1 for binding to recombinant TTR in buffer and with S2 for binding to endogenous levels of TTR in human blood serum. In both assay scenarios, we demonstrate that the lower the TTR-stilbene conjugate fluorescence after a 3 h competition, the greater the binding selectivity and potency of the candidate TTR kinetic stabilizer. These assays, particularly the assay utilizing S2 in human serum, replace two assays previously utilized to gather the same information. While not the focus of this manuscript, it is clear that the 'TTR fluorescence conjugate competition assay' could be adapted for high throughput screening applications. © 2011 Elsevier Ltd. All rights reserved. Source

Cho H.,Chungnam National University
Journal of the Korean Physical Society | Year: 2011

Motivated by the previous observation [Kato et al., J. Chem. Phys. 132, 074309 (2010)] that the structure seen in the elastic electron scattering cross sections from CH 3X (X = F, Cl, Br, and I) molecules at intermediate energies (50 - 200 eV) is also found, at least in part, in the corresponding noble gas species, we measured differential cross sections for the elastic scattering of electrons from CH 3Cl at the low incident electron energies of 5, 10, and 20 eV for scattering angles from 20° up to 180°. We confirmed that, as we went to lower electron energies, the "atomic-like" behavior faded out, and the "molecular-like" behavior became increasingly prominent. Source

Kim W.,Korea Advanced Institute of Science and Technology | Doh S.-J.,Korea University | Yu Y.,Chungnam National University | Lee Y.I.,Seoul National University
Marine Geology | Year: 2013

To identify the provenance of fine-grained sediments in the northern East China Sea, various magnetic parameters indicating concentration (magnetic susceptibility, susceptibility of anhysteretic remanent magnetization (χARM), and saturation of isothermal remanent magnetization (SIRM)), mineral composition (S300=-IRM-300mT/SIRM and HIRM (%)=50 (SIRM-IRM300mT)/SIRM), and grain size (frequency-dependent magnetic susceptibility (χFD), χARM/SIRM, and S20=IRM20mT/SIRM) were measured from surface sediments collected at 98 regularly spaced sites. As an unbiased analytic tool, fuzzy clustering analysis was performed on data from 97 sites except an outlier. Each dataset for each site comprised magnetic parameters representing ultrafine superparamagnetic (χFD), fine single-domain or pseudo-single-domain (χARM/SIRM), and coarse multidomain (S20) fractions, and the relative dominance of low- and high-coercivity minerals (S300 and HIRM (%), respectively). The statistical analysis yielded four clusters, indicating that the sediments in the study area can be differentiated magnetically. Of the magnetic properties of the cluster centers, the most distinctive feature of cluster 1 is a predominance of coarse-grained magnetic minerals (highest S20 value), while the contribution of high-coercivity minerals is highest in cluster 2 (highest HIRM (%) value). Ultrafine- and fine-grained fractions are prominent in cluster 3 (highest χFD and χARM/SIRM values), while cluster 4 has the highest ratio of low- to high-coercivity minerals (highest S300 value). Related to sediment provenance, the sediments of cluster 1 are interpreted to have been derived from the Yangtze River in China. The old Yellow River deposits are the primary source of sediments in cluster 2. Sediments in cluster 3 were probably transported from Taiwan or the Northwest Pacific by the Taiwan Warm Current or the Kuroshio Current, respectively, while Korean river deposits are the most probable sources of sediments in cluster 4. © 2013 Elsevier B.V. Source

To identify genes associated with genic male sterility (GMS) that could be useful for hybrid breeding in Chinese cabbage (Brassicarapa ssp. pekinensis), floral bud transcriptome analysis was carried out using a B. rapa microarray with 300,000 probes (Br300K). Among 47,548 clones deposited on a Br300K microarray with seven probes of 60 nt length within the 3' 150 bp region, a total of 10,622 genes were differentially expressed between fertile and sterile floral buds; 4,774 and 5,848 genes were up-regulated over 2-fold in fertile and sterile buds, respectively. However, the expression of 1,413 and 199 genes showed fertile and sterile bud-specific features, respectively. Genes expressed specifically in fertile buds, possibly GMS-related genes, included homologs of several Arabidopsis male sterility-related genes, genes associated with the cell wall and synthesis of its surface proteins, pollen wall and coat components, signaling components, and nutrient supplies. However, most early genes for pollen development, genes for primexine and callose formation, and genes for pollen maturation and anther dehiscence showed no difference in expression between fertile and sterile buds. Some of the known genes associated with Arabidopsis pollen development showed similar expression patterns to those seen in this study, while others did not. BrbHLH89 and BrMYP99 are putative GMS genes. Additionally, 17 novel genes identified only in B. rapa were specifically and highly expressed only in fertile buds, implying the possible involvement in male fertility. All data suggest that Chinese cabbage GMS might be controlled by genes acting in post-meiotic tapetal development that are different from those known to be associated with Arabidopsis male sterility. Source

Kim H.,University of Florida | Jang Y.-C.,Chungnam National University | Townsend T.,University of Florida
Journal of Hazardous Materials | Year: 2011

The long-term behavior and fate of metals in leachate from four simulated bioreactor landfills were explored using lysimeters under both aerobic and anaerobic conditions for a maximum of 1650 days. Metal concentrations varied with time and stage of landfill activity. The behavior of selected metals (Al, As, Cr, Cu, Fe, Pb, and Zn) significantly differed between aerobic and anaerobic conditions. Leachate from the aerobic lysimeters contained greater concentrations of Al, Cu, and Pb compared to leachate derived from the anaerobic lysimeters (average concentrations of Al, Cu and Pb in the aerobic/anaerobic lysimeters were 8.47/0.78. mg/L, 1.61/0.04. mg/L and 0.10/0.03. mg/L, respectively). In the anaerobic lysimeters, As, Fe and Zn leached at greater concentrations (average concentrations of As, Fe and Zn in the aerobic/anaerobic lysimeters were 0.40/1.14. mg/L, 13.5/136. mg/L and 15.3/168. mg/L, respectively). Though no significant difference in overall Cr concentrations was observed in leachate samples from aerobic and anaerobic lysimeters, during the alkali and methane phases approximately 45% of Cr was presented as Cr(VI) under aerobic conditions, whereas no Cr(VI) was detected under anaerobic conditions. © 2011 Elsevier B.V. Source

Lee S.,Korea Advanced Institute of Science and Technology | Kim C.-Y.,Chungnam National University | Hong S.,Korea Advanced Institute of Science and Technology
IEEE Transactions on Microwave Theory and Techniques | Year: 2012

This paper presents a K-band CMOS UWB radar transmitter with highly accurate variable delay circuits and a bi-phase modulating pulsed oscillator. The UWB radar transmitter is composed of three blocks: variable delay circuits that consist of a digital synchronized counter and a Vernier delay line (VDL), a baseband control signal generator, and a pulsed oscillator. The VDL allows a high range accuracy level of several millimeters. Asymmetric signals generated by the baseband control signal generator can control the phase of each output pulse. Because the pulsed oscillator operates only for the duration of a pulse, it has an extremely low level of DC power consumption and no LO leakage. It is fabricated with 0.13-μm CMOS technology and a chip with dimensions of 0.98 mm × 0.69 mm. The output spectrum is centered at 26.0 GHz, and the pulse width is controllable from 280 to 680 ps. The peak output power is about 2 dBm. © 2012 IEEE. Source

Shin J.W.,Korea Aerospace Research Institute | Lee Y.-S.,Chungnam National University
International Journal of Solids and Structures | Year: 2010

The dynamic propagation of an interface crack between two dissimilar functionally graded piezoelectric material (FGPM) layers under anti-plane shear is analyzed using the integral transform method. The properties of the FGPM layers vary continuously along the thickness. The properties of the FGPM layers vary differently and the two layers are connected weak-discontinuously. A constant velocity Yoffe-type moving crack is considered. Fourier transform is used to reduce the problem to two sets of dual integral equations, which are then expressed to the Fredholm integral equations of the second kind. Numerical values on the dynamic energy release rate (DERR) are presented for the FGPM to show the effects on the electric loading, gradient of material properties, crack moving velocity, and thickness of layers. Followings are helpful to increase of the resistance of the interface crack propagation of FGPM: (a) certain direction and magnitude of the electric loading; (b) increase of the gradient of material properties; (c) increase of the material properties from the interface to the upper and lower free surface; (d) increase of the thickness of FGPM layer. The DERR increases or decreases with increase of the crack moving velocity. © 2010 Elsevier Ltd. All rights reserved. Source

Jung J.-Y.,Electronics and Telecommunications Research Institute | Park C.-W.,Electronics and Telecommunications Research Institute | Yeom K.-W.,Chungnam National University
IEEE Transactions on Microwave Theory and Techniques | Year: 2012

In this paper, a novel carrier leakage suppression (CLS) front-end for UHF RF identification (RFID) reader is presented. We demonstrated through experiment in the laboratory environment that the proposed CLS front-end has a significant improvement in the carrier-to-data ratio by more than 36 dBc in the UHF RFID frequency band. When inserted between the antenna and a Class-1 RFID reader, measurements show that the reader can successfully demodulate the generated tag signal for a power level of -80 dBm, which corresponds to the backscattered power at 20-m distance. The read range of the reader with the proposed CLS front-end is verified again in an indoor environment. The measured read range is found to be about 23 m for a commercial battery-assisted passive (BAP) tag. We showed that a Class-3 RFID system for a long read range of 20 m can be successfully established with BAP tags and the Class-1 reader with the proposed CLS front-end. © 2012 IEEE. Source

HL-1 cells are the adult cardiac cell lines available that continuously divide while maintaining an atrial phenotype. Here we examined the expression and localization of inositol 1,4,5-trisphosphate receptor (IP(3)R) subtypes, and investigated how pattern of IP(3)-induced subcellular local Ca(2+) signaling is encoded by multiple IP(3)R subtypes in HL-1 cells. The type 1 IP(3)R (IP(3)R1) was expressed in the perinucleus with a diffuse pattern and the type 2 IP(3)R (IP(3)R2) was expressed in the cytosol with a punctate distribution. Extracellular ATP (1 mM) elicited transient intracellular Ca(2+) releases accompanied by a Ca(2+) oscillation, which was eliminated by the blocker of IP(3)Rs, 2-APB, and attenuated by ryanodine. Direct introduction of IP(3) into the permeabilized cells induced Ca(2+) transients with Ca(2+) oscillations at [Symbol: see text] 20 muM of IP(3), which was removed by the inhibition of IP(3)Rs using 2-APB and heparin. IP(3)-induced local Ca(2+) transients contained two distinct time courses: a rapid oscillation and a monophasic Ca(2+) transient. The magnitude of Ca(2+) oscillation was significantly larger in the cytosol than in the nucleus, while the monophasic Ca(2+) transient was more pronounced in the nucleus. These results provide evidence for the molecular and functional expression of IP(3)R1 and IP(3)R2 in HL-1 cells, and suggest that such distinct local Ca(2+) signaling may be correlated with the punctate distribution of IP(3)R2s in the cytosol and the diffuse localization of IP(3)R1 in the peri-nucleus. Source

Nam K.-C.,Sunchon National University | Jo C.,Chungnam National University | Lee M.,Seoul National University | Lee M.,Korea Food Research Institute
Meat Science | Year: 2010

Food consumption is a basic activity necessary for survival of the human race and evolved as an integral part of mankind's existence. This not only includes food consumption habits and styles but also food preparation methods, tool development for raw materials, harvesting and preservation as well as preparation of food dishes which are influenced by geographical localization, climatic conditions and abundance of the fauna and flora. Food preparation, trade and consumption have become leading factors shaping human behavior and developing a way of doing things that created tradition which has been passed from generation to generation making it unique for almost every human niche in the surface of the globe. Therefore, the success in understanding the culture of other countries or ethnic groups lies in understanding their rituals in food consumption customs. Meat consumption culture in the East has not been well developed by its characteristic environment, religion, history, and main food staples. However, recently, the amount of meat production and consumption of the Eastern countries has grown rapidly by the globalization of food industry and rapid economic growth of the countries. This manuscript introduces meat-based products and consumption culture in Asian countries. However, because the environments and cultures within Asia are too diverse to cover all food cultures, this manuscript focused mainly on three northeast Asian countries including China, Japan, and Korea (Republic of) and some southeast Asian countries including Vietnam and Thailand, which have similar environments and cultural interactions historically but retain their own characteristic food culture. © 2010 The American Meat Science Association. Source

Cho H.O.,Chungnam National University
Molecules and cells | Year: 2010

The highly polymorphic porcine major histocompatibility complex (MHC), or the swine leukocyte antigens (SLA), has been repeatedly associated with variations in swine immune response to pathogens and vaccines as well as with production traits. The SLA antigens are also important targets for immunological recognition of foreign tissue grafts. We recently established a resource population of Korean native pigs as models for human transplantation and xenotransplantation research. In this study, 115 animals derived from three generations of the Korean native pigs were genotyped for three SLA class I (SLA-2, SLA-3 and SLA-1) and three SLA class II loci (DRB1, DQB1, DQA) using PCR with sequence-specific primers (PCR-SSP) at the allele group resolution. A total of seven SLA haplotypes (Lr-5.34, Lr-7.23, Lr-31.13, Lr-56.23, Lr-56.30, Lr-59.1, Lr-65.34), comprising six unique class I and five unique class II haplotypes, were characterized in the founding animals. Class I haplotype Lr-65.0 and class II haplotype Lr-0.34 were novel; and together with Lr-56.0 these haplotypes appeared to be breed-specific. In the progeny population, Lr-7.23 and Lr-56.30 appeared to be the most prevalent haplotypes with frequencies of 34.7% and 31.6%, respectively; the overall homozygosity was 27.4%. This resource population of SLA-defined Korean native pigs will be useful as large animal models for various transplantation and xenotransplantation experiments, as well as for dissecting the roles of SLA proteins in swine disease resistance and production traits. Source

Ingole P.G.,Korea Institute of Energy Research | Ingole N.P.,Chungnam National University
Korean Journal of Chemical Engineering | Year: 2014

The discrimination of enantiomers is a challenging task in separation technology, and using a membrane is most promising for separating enantiomers from racemic mixture. The optical resolution of chiral compounds is of interest to researchers working in a variety of fields from analytical, organic and medicinal chemistry, to pharmaceutics and materials, to process engineering for fabricating pharmaceuticals, agrochemicals, fragrances and foods, and so on. There is considerable demand for separation techniques appropriate for the large-scale resolution of chiral molecules. The separation of chiral compounds using chiral or achiral/non-chiral polymeric membranes with or without chiral selector represents a promising system for future commercial applications. This review focuses on an active field of chiral separation, membrane-based enantioseparation technique, which has potential for large-scale production of singleenantiomers. Enantiomeric separation by membrane processes has been studied using various configurations of liquid and solid polymer membranes. Selectivity and permeability of liquid-membranes is reasonably good because the rate of diffusion of solute molecules is high in liquids but has inferior durability and stability. Solid polymer membranes have inferior permeability because diffusion of solute through solids is slow but quite stable and durable; however, commercial application of membrane technology for optical resolution is yet to be realized. Several chiral separation membranes were prepared from chiral polymers where enantioselectivity was generated from chiral carbons in the main chain. However, it is rather tricky to generate excellent chiral separation membranes from chiral polymers alone, because racemic penetrants mainly encounter the flexible side chains of the membrane polymers. © 2014, Korean Institute of Chemical Engineers, Seoul, Korea. Source

Jayasena D.D.,Chungnam National University | Jayasena D.D.,Uva Wellassa University | Jo C.,Seoul National University
Food Reviews International | Year: 2014

This review provides an overview of the published data on the antioxidative potentials of common essential oils and their components that could be considered suitable for application to meat and meat products. The positive effects of essential oils from oregano, rosemary, thyme, sage, basilica, ginger, and others, when used alone or in combination with other essential oils and/or as a part of hurdle technology to extend product shelf life by controlling lipid oxidation and improving the sensory qualities of meat and meat products, are well documented. Phenolic constituents of many of these essential oils act as free radical scavengers and hydrogen donators that prevent lipid oxidation. © 2014 Copyright Taylor and Francis Group, LLC. Source

Beers T.C.,University of Notre Dame | Norris J.E.,Australian National University | Placco V.M.,Gemini Observatory | Lee Y.S.,Chungnam National University | And 3 more authors.
Astrophysical Journal | Year: 2014

A new set of very high signal-to-noise (S/N > 100/1), medium-resolution (R ∼ 3000) optical spectra have been obtained for 302 of the candidate "weak-metal" stars selected by Bidelman & MacConnell. We use these data to calibrate the recently developed generalization of the Sloan Extension for Galactic Exploration and Understanding and Exploration (SEGUE) Stellar Parameter Pipeline, and obtain estimates of the atmospheric parameters (Teff, log g, and [Fe/H]) for these non-Sloan Digital Sky Survey/SEGUE data; we also obtain estimates of [C/Fe]. The new abundance measurements are shown to be consistent with available high-resolution spectroscopic determinations, and represent a substantial improvement over the accuracies obtained from the previous photometric estimates reported in Paper I of this series. The apparent offset in the photometric abundances of the giants in this sample noted by several authors is confirmed by our new spectroscopy; no such effect is found for the dwarfs. The presence of a metal-weak thick-disk (MWTD) population is clearly supported by these new abundance data. Some 25% of the stars with metallicities -1.8 < [Fe/H] ≤-0.8 exhibit orbital eccentricities e < 0.4, yet are clearly separated from members of the inner-halo population with similar metallicities by their location in a Lindblad energy versus angular momentum diagram. A comparison is made with recent results for a similar-size sample of Radial Velocity Experiment stars from Ruchti et al. We conclude, based on both of these samples, that the MWTD is real, and must be accounted for in discussions of the formation and evolution of the disk system of the Milky Way. © 2014 The American Astronomical Society. All rights reserved. Source

Yun H.-D.,Chungnam National University | Choi W.-C.,North Carolina A&T State University | Seo S.-Y.,Chungbuk National University
NDT and E International | Year: 2010

In this study, the applicability of acoustic emission (AE) techniques to monitor damage evolution in reinforced concrete (RC) beams strengthened in flexure with carbon fiber reinforced polymer (CFRP) sheets is investigated. The objective is to initiate the creation of a user-friendly health monitoring system for RC structures strengthened with CFRP sheets using AE techniques. Five beams, 200 mm×300 mm in cross-section, were tested under three-point bending over a span of 1700 mm. One of the beams was tested in its virgin condition to serve as reference; the remaining four beams were tested after being strengthened with CFRP sheets bonded on the tension face. The parameters investigated in this study include both the amount of CFRP sheets and construction imperfections (the CFRP sheets were intentionally bonded without adhesive in the centermost 10% and 20% bonding area). The AE signals were collected and analyzed for all specimens. The AE parameters were analyzed for four levels of damage based on initial crack, propagation, yielding of main bars, and fracture or rip-off of the CFRP sheets. The frequency-peak magnitude distribution of the AE parameters was used to determine the b-value, defined by the GutenbergRichter relationship, for evaluating the damage evolution and fracture process of RC beams strengthened in flexure with CFRP sheets. From the results of this study, the signal characteristics event, amplitude versus frequency, and amplitude versus duration show clear differences in the different loading stages, depending upon the active damage mechanism. The b-value is correlated to the fracture process of the RC beams bonded with CFRP sheets and the degree of localization of damage. The AE technique is a useful nondestructive technique for monitoring the behavior of RC beams that are externally reinforced in flexure with CFRP sheets. © 2010 Elsevier Ltd. Source

Son D.W.,Korea Forestry Research Institute | Kang S.-G.,Chungnam National University
Journal of the Korean Wood Science and Technology | Year: 2014

The purpose of this study is to analyze fundamental combustion characteristics of woods used for indoor applications. The combustion characteristics such as heat release rate, total heat release, gas yield, and mass loss were analyzed by the method of cone calorimeter or thermogravimetry. These analysis results show that material properties of wood are closely related to flammability. It was shown that the relationship between the mass loss and gas emission. The results of combustion properties of woods would be useful for fundamentals of guiding the safe use of wood indoor application. Source

Cho J.,Chungnam National University
Journal of Physics: Conference Series | Year: 2016

Electron magnetohydrodynamics (EMHD) provides a simple fluid-like description of physics below the proton gyro-scale in collisionless plasmas, such as the solar wind. In this paper, we discuss forward and inverse cascades in EMHD turbulence in the presence of a strong mean magnetic field. Similar to Alfvén waves, EMHD waves, or EMHD perturbations, propagate along magnetic field lines. Therefore, two types of EMHD waves can exist: waves moving parallel to and waves moving anti-parallel to the the magnetic field lines. For energy cascade in EMHD turbulence, the relative amplitudes of opposite-traveling waves are important. When the amplitudes are balanced, we will see fully-developed forward cascade with a k -7/3 energy spectrum and a scale-dependent anisotropy. On the other hand, when the amplitudes are imbalanced, we will see inverse cascade, as well as (presumably not fully developed) forward cascade. The underlying physics for the inverse cascade is magnetic helicity conservation. Source

Das M.,National Physical Laboratory India | Sumana G.,National Physical Laboratory India | Nagarajan R.,University of Delhi | Malhotra B.D.,National Physical Laboratory India | Malhotra B.D.,Chungnam National University
Applied Physics Letters | Year: 2010

Nanostructured zirconium oxide (ZrO2) film (particle size∼35 nm), electrochemically deposited onto gold(Au) surface, has been used to immobilize 21-mer oligonucleotide probe (ssDNA) specific to Mycobacterium tuberculosis by utilizing affinity between oxygen atom of phosphoric group and zirconium to fabricate DNA biosensor. This DNA- ZrO2 /Au bioelectrode, characterized using x-ray diffraction, Fourier transform infrared spectroscopy, cyclic voltammetry, and scanning electron microscopy techniques, can be used for early and rapid diagnosis of M. tuberculosis with detection limit of 0.065 ng/μL within 60s. © 2010 American Institute of Physics. Source

Shahid M.,Sungkyunkwan University | Shakir I.,Sungkyunkwan University | Yang S.-J.,Chungnam National University | Kang D.J.,Sungkyunkwan University
Materials Chemistry and Physics | Year: 2010

One-dimensional SnO2/V2O5 core-shell nanowires were synthesized by a combination of hydrothermal and wet chemical routes at room temperature. The photocatalytic behavior of the SnO 2/V2O5 nanowires for the photodegradation of toluidine blue "O" dye (TBO) under UV exposure was examined. SnO 2/V2O5 showed better photocatalytic activity than V2O5 nanowires and bulk. The significant enhancement of the photocatalytic activity of the core-shell SnO2/V 2O5 nanowires was attributed mainly to its large specific surface area and efficient charge separation at the SnO2/V 2O5 photocatalyst interface. © 2010 Elsevier B.V. All rights reserved. Source

Kang J.U.,Korea Nazarene University | Koo S.H.,Chungnam National University
International Journal of Molecular Medicine | Year: 2012

Microarray-based cytogenetics is revealing the tremendous fluidity and complexity of the human genome, and is starting to illustrate the implications of genomic variability with respect to human health and disease. In the last few years, the robustness of array-based technologies has provided accurate diagnosis and appropriate clinical management in a timely and efficient manner for identifying genomic defects of congenital and developmental abnormalities including developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASD) and/or multiple congenital anomalies (MCA). The implementation of this technology in these categories of disorders has been thoroughly evaluated and is now recommended as a first-line diagnostic approach for clinically suspected genetic disorders. However, clinical application of array-CGH in postnatal evaluation raises the debate of whether array-CGH will replace traditional cytogenetics in the near future and whether there is still a role for karyotyping and FISH. In this article, we therefore review the current status of array-based technology use for postnatal diagnosis and predict that it will replace standard cytogenetics as a first-line test for clinical evaluation in these population groups. Source

Choi S.H.,Chungnam National University | Suzuki K.,Japan Agency for Marine - Earth Science and Technology | Mukasa S.B.,University of Michigan | Lee J.-I.,Korea Polar Research Institute | Jung H.,Seoul National University
Earth and Planetary Science Letters | Year: 2010

The timing of sub-continental lithospheric mantle (SCLM) differentiation beneath Spitsbergen, western Svalbard, has been determined with spinel peridotite xenoliths using two complementary isotopic systems: Lu-Hf and Re-Os. The whole-rock Re-Os systematics (Re-Os errorchron, aluminochron, and Re-depletion age) define Paleoproterozoic/Neoarchean ages for isolation of the studied peridotites from the convecting mantle. We note that the age is independently supported by the Lu-Hf errorchron for the peridotite clinopyroxene grains, and average degree of melt depletion recorded in the samples. The obtained ages are indistinguishable from the oldest crustal ages reported in western Spitsbergen, implying that the mantle lithosphere in this area was stabilized at the same time as formation of the overlying crust. Our data suggest that the Spitsbergen lithosphere is unlikely to have undergone bulk lithospheric delamination since the tectonic transition from transpressional to transtensional which commenced in the Paleocene. We thus discount the delaminated and reactivated SCLM as a potential source for the Dupal-like enriched components in the Arctic upper mantle suggested by other studies. © 2010 Elsevier B.V. Source

Park J.,Chungnam National University | Logan K.J.,University of Florida
Journal of Fluency Disorders | Year: 2015

Purpose: Adults who stutter speak more fluently during choral speech contexts than they do during solo speech contexts. The underlying mechanisms for this effect remain unclear, however. In this study, we examined the extent to which the choral speech effect depended on presentation of intact temporal speech cues. We also examined whether speakers who stutter followed choral signals more closely than typical speakers did. Method: 8 adults who stuttered and 8 adults who did not stutter read 60 sentences aloud during a solo speaking condition and three choral speaking conditions (240 total sentences), two of which featured either temporally altered or indeterminate word duration patterns. Effects of these manipulations on speech fluency, rate, and temporal entrainment with the choral speech signal were assessed. Results: Adults who stutter spoke more fluently in all choral speaking conditions than they did when speaking solo. They also spoke slower and exhibited closer temporal entrainment with the choral signal during the mid- to late-stages of sentence production than the adults who did not stutter. Both groups entrained more closely with unaltered choral signals than they did with altered choral signals. Conclusions: Findings suggest that adults who stutter make greater use of speech-related information in choral signals when talking than adults with typical fluency do. The presence of fluency facilitation during temporally altered choral speech and conversation babble, however, suggests that temporal/gestural cueing alone cannot account for fluency facilitation in speakers who stutter. Other potential fluency enhancing mechanisms are discussed.Educational Objectives: The reader will be able to (a) summarize competing views on stuttering as a speech timing disorder, (b) describe the extent to which adults who stutter depend on an accurate rendering of temporal information in order to benefit from choral speech, and (c) discuss possible explanations for fluency facilitation in the presence of inaccurate or indeterminate temporal cues. © 2015 Elsevier Inc. Source

Gee J.S.,University of California at San Diego | Yu Y.,Chungnam National University | Bowles J.,University of Minnesota
Geochemistry, Geophysics, Geosystems | Year: 2010

Ash flow tuffs, or ignimbrites, typically contain fine-grained magnetite, spanning the superparamagnetic to single-domain size range that should be suitable for estimating geomagnetic field intensity. However, ignimbrites may have a remanence of thermal and chemical origin as a result of the complex magnetic mineralogy and variations in the thermal and alteration history. We examined three stratigraphic sections through the ∼0.76 Ma Bishop Tuff, where independent information on postemplacement cooling and alteration is available, as a test of the suitability of ignimbrites for paleointensity studies. Thermomagnetic curves suggest that low-Ti titanomagnetite (T c = 560°C-580°C) is the dominant phase, with a minor contribution from a higher Tc phase(s). Significant remanence unblocking above 580°C suggests that maghemite and/or (titano)maghemite is an important contributor to the remanence in most samples. We obtained successful paleofield estimates from remanence unblocked between 440°C and 580°C for 46 of 89 specimens (15 sites at two of three total localities). These specimens represent a range of degrees of welding and have variable alteration histories and yet provide a consistent paleofield estimate of 43.0 μT (±3.2), equivalent to a VADM of 7.8 × 1022 Am 2. The most densely welded sections of the tuff have emplacement temperatures inferred to be as high as ∼660°C, suggesting that the remanence may be primarily thermal in origin, though a contribution from thermochemical remanence cannot be excluded. These results suggest that ignimbrites may constitute a viable material for reliable paleointensity determinations. Copyright 2010 by the American Geophysical Union. Source

Tsunetsugu Y.,Japan Forestry and Forest Products Research Institute | Lee J.,Korea Forest Service | Park B.-J.,Chungnam National University | Tyrvainen L.,Finnish Forest Research Institute | And 2 more authors.
Landscape and Urban Planning | Year: 2013

The present study investigated the physiological and psychological effects of viewing urban forest landscapes on 48 young male urban residents. Four forested areas and four urban areas located in central and western Japan were used as the test sites. We found that in the forested areas, the subjects exhibited (i) significantly lower diastolic blood pressure, (ii) significantly higher parasympathetic nervous activity, but significantly lower sympathetic nervous activity, and (iii) significantly lower heart rate. The forest landscapes (iv) obtained better scores in subjective ratings, and (v) induced significantly less negative and more vigorous moods. Taken as whole, these findings suggest that even a short-term viewing of forests has relaxing effects. We have thus concluded that the approach taken in this study is useful in exploring the influences of urban green space on humans, as well as contributing to the planning and design of a healthy environment for urban residents. © 2013 Elsevier B.V. Source

Kim D.-W.,Chungnam National University
IEEE Microwave and Wireless Components Letters | Year: 2015

This letter proposes an effective output matching technique using drain shunt capacitors with tapered capacitance values for a GaN distributed power amplifier MMIC to simultaneously obtain optimum load impedance for maximum output power of each transistor and phase velocity balance between input and output artificial transmission lines as well as length reduction of the transmission lines. To support its plausibility, a 2-6 GHz 10 W distributed power amplifier MMIC is designed and fabricated using a 0.25 μm GaN HEMT process of WIN Semiconductors. Measurement of the S parameters and CW output power demonstrates successful operation of the proposed technique in the design frequency range. © 2015 IEEE. Source

Hua S.,University of California at Davis | An H.J.,Chungnam National University | Ozcan S.,University of California at Davis | Ro G.S.,University of California at Davis | And 3 more authors.
Analyst | Year: 2011

Glycosylation is highly sensitive to the biochemical environment and has been implicated in many diseases including cancer. Glycan compositional profiling of human serum with mass spectrometry has already identified potential biomarkers for several types of cancer and diseases; however, composition alone does not fully describe glycan stereo- and regioisomeric diversity. The vast structural heterogeneity of glycans presents a formidable analytical challenge. We have developed a method to identify and quantify isomeric native glycans using nanoflow liquid chromatography (nano-LC)/mass spectrometry. A microfluidic chip packed with graphitized carbon was used to chromatographically separate the glycans. To determine the utility of this method for structure-specific biomarker discovery, we analyzed serum samples from two groups of prostate cancer patients with different prognoses. More than 300 N-glycan species (including isomeric structures) were identified, corresponding to over 100 N-glycan compositions. Statistical tests established significant differences in glycan abundances between patient groups. This method provides comprehensive, selective, and quantitative glycan profiling. © 2011 The Royal Society of Chemistry. Source

Jeong Y.G.,Chungnam National University | An J.-E.,H&SHighTech Corporation
Macromolecular Research | Year: 2014

UV-cured epoxy hybrid composite films were manufactured by efficient and facile cationic photochemical polymerization of 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate mixtures including 5.0 wt% carbon nanofillers of different graphene/multi-walled carbon nanotube (MWCNT) compositions of 10/0, 9/1, 7/3, 5/5, 3/7, and 0/10 by weight ratio. TEM images confirmed that the mixed carbon nanofillers of graphene and MWCNT were well dispersed in the UV-cured epoxy matrix, while MWCNT as a single carbon nanofiller component was aggregated in the matrix. The electrical resistivity of the composite films was thus varied with the increment of the relative MWCNT content in 5.0 wt% carbon nanofillers, i.e., ∼160 Ωcm for the epoxy/graphene composite film, 30∼80 Ωcm for the epoxy/graphene/MWCNT composite films, and ∼16,200 Ωcm for the epoxy/MWCNT composite film. The decreased electrical resistivity of the epoxy/graphene/MWCNT composite films was associated with the interconnected network formation of graphene sheets and MWCNTs. Thus the UV-cured epoxy/graphene and epoxy/graphene/MWCNT composite films exhibited excellent electric heating performance in terms of rapid temperature response, stable maximum temperature, and high electric power efficiency. In addition, the UV-cured epoxy hybrid composite films as electric heating materials were found to be thermally stable up to ∼290 °C.[Figure not available: see fulltext.]. © 2014, The Polymer Society of Korea and Springer Sciene+Business Media Dordrecht. Source

Kang J.U.,Korea Nazarene University | Koo S.H.,Chungnam National University
International Journal of Molecular Medicine | Year: 2012

The lymph node metastatic (LNM) spread of tumor cells is a frequent event in the initial process of cancer dissemination and is a powerful independent prognostic indicator in gastric adenocarcinoma (GAC). High density genomic arrays were conducted to identify molecular markers associated with lymph node metastasis in GAC. In the genome-wide profile, large copy number gains involving chromosomes 1p, 3q, 8q, 9q, 11q, 16p, 19p, and 20q (log2 ratio >0.25) (>40% of patients) were more prevalent than copy number losses. The most notable finding was copy number gains at the long arm of chromosome 11, which occurred in 75.0% of lymphatic metastasis GAC cases, and the delineated minimal common region was 11q24.2-q12.1. More specifically, 2 amplified (>1 log2 ratio) loci on the 11q13.3 region were detected in 12.5% of the cases. The first locus, covers a region of ∼7.7 Mbp, and comprises the representative oncogene of cyclin D1 (CCNDI). This finding occurred in 12.5% of the cases. Additionally, an oral cancer overexpressed 1 (ORAOV1) gene was identified as a probable target within the 11q13 amplicon, which previously was not assumed to play a pathogenic role in GACs (12.5%). A second locus spanning 7.8 Mbp on 11q13.3 without associated genes also showed high-level amplifications in 12.5% of the GACs. This study indicates that the long arm of chromosome 11 harbors protooncogenes that are associated with lymphatic metastasis formation and the ORAOV1 gene at the 11q13.3 region could be a potential target and serve as an indicator for the presence of occult metastases in GAC. Source

Lee H.K.,Hanyang University | Park B.-Y.,Chungnam National University | Rho M.,Hanyang University | Rho M.,CEA Saclay Nuclear Research Center
Physical Review C - Nuclear Physics | Year: 2011

In a previous article, the four-dimensional (4D) half-Skyrmion (or five-dimensional dyonic salt) structure of dense baryonic matter described in crystalline configuration in the large Nc limit was shown to have nontrivial consequences on how antikaons behave in compressed nuclear matter with a possible implication for the "ice-9" phenomenon of deeply bound kaonic matter and condensed kaons in compact stars. We extend the analysis to make a further prediction on the scaling properties of hadrons that have a surprising effect on the nuclear tensor forces, the symmetry energy, and hence on the phase structure at high density. We treat this problem, relying on certain topological structures of chiral solitons. Combined with what can be deduced from hidden local symmetry for hadrons in a dense medium and the "soft" dilatonic degree of freedom associated with the trace anomaly of QCD, we uncover a novel structure of chiral symmetry in the "supersoft" symmetry energy that can influence the structure of neutron stars. © 2011 American Physical Society. Source

Lee J.-Y.,Korea Advanced Institute of Science and Technology | Kim Y.-R.,Korea Advanced Institute of Science and Technology | Kim Y.-R.,Chungnam National University | Park J.,Korea Advanced Institute of Science and Technology | Kim S.,Korea Advanced Institute of Science and Technology
Annals of the New York Academy of Sciences | Year: 2012

Inositol phosphates (IPs) act as signaling messengers to regulate various cellular processes such as growth. Inositol polyphosphate multikinase (IPMK) generates inositol tetrakis- and pentakisphosphates (IP4 and IP5), acting as a key enzyme for inositol polyphosphate biosynthesis. IPMK was initially discovered as an essential subunit of the arginine-sensing transcription complex in budding yeast. In mammals, IPMK is also known as a physiologically important phosphatidylinositol 3 kinase (PI3K) that forms phosphatidylinositol 3,4,5-trisphosphate (PIP3), which activates Akt/PKB and stimulates its signaling. Acting in a catalytically independent fashion, IPMK mediates the activation of mammalian target of rapamycin (mTOR) in response to essential amino acids. In addition, IPMK binds and modulates AMP-activated protein kinase (AMPK) signaling pathways, including those involved in hypothalamic control of food intake. These recent findings strongly suggest that IPMK is a versatile player in insulin-, nutrient-, and energy-mediated metabolism signaling networks. Agents that control IPMK functions may provide novel therapeutics in metabolic syndromes such as obesity and diabetes. © 2012 New York Academy of Sciences. Source

Chung H.,Chungnam National University | Choi H.,National Forensic Service | Heo S.,National Forensic Service | Kim E.,National Forensic Service | Lee J.,National Forensic Service
Forensic Toxicology | Year: 2014

The rapid increase in the number of new psychoactive substances and their abuse is the most recent drug abuse issue worldwide. Although abuse of synthetic cannabinoids is highly restricted in South Korea, the rapid increase in the number of new substances is forcing the legal regulation authority to continuously improve the drug regulation act. As a result of drug screening by the National Forensic Service from 2009 to June 2013, 26 species of synthetic cannabinoids were identified in materials seized mainly by the Police Agency and the Prosecutor's Office in South Korea. One of the most remarkable trends in synthetic cannabinoids is the increase in halogenated derivatives and new substances, including UR-144 and A-836,339 originally developed as analgesics by Abbott Laboratories. The N-pentyl fluorinated analog of UR-144 (XLR-11) has become the most frequently found synthetic cannabinoid in 2013 since its first appearance in 2012, whereas abuse of A-836,339 analogs has been little reported despite their abuse potential. Until early 2011, nicotine was the most frequently found active coingredient with synthetic cannabinoids. However, various psychoactive substances such as Δ9- tetrahydrocannabinol, α-pyrrolidinobutiophenone, α- pyrrolidinovalerothiophenone, and N,N-diallyl-5-methoxytryptamine have often been found as coingredients in herbal highs since late 2011. These coingredients should also be systematically regulated, because they can cause unexpected side effects. It is suggested that authorities in different countries share information about synthetic cannabinoids and their coingredients. © 2013 Japanese Association of Forensic Toxicology and Springer Japan. Source

Kim M.S.,Chungnam National University
International journal of nanomedicine | Year: 2011

The aim of this study was to improve the physicochemical properties and bioavailability of poorly water-soluble sirolimus via preparation of a solid dispersion of nanoparticles using a supercritical antisolvent (SAS) process. First, excipients for enhancing the stability and solubility of sirolimus were screened. Second, using the SAS process, solid dispersions of sirolimus-polyvinylpyrrolidone (PVP) K30 nanoparticles were prepared with or without surfactants such as sodium lauryl sulfate (SLS), tocopheryl propylene glycol succinate, Sucroester 15, Gelucire 50/13, and Myrj 52. A mean particle size of approximately 250 nm was obtained for PVP K30-sirolimus nanoparticles. Solid state characterization, kinetic solubility, powder dissolution, stability, and pharmacokinetics were analyzed in rats. X-ray diffraction, differential scanning calorimetry, and high-pressure liquid chromatography indicated that sirolimus existed in an anhydrous amorphous form within a solid dispersion of nanoparticles and that no degradation occurred after SAS processing. The improved supersaturation and dissolution of sirolimus as a solid dispersion of nanoparticles appeared to be well correlated with enhanced bioavailability of oral sirolimus in rats. With oral administration of a solid dispersion of PVP K30-SLS-sirolimus nanoparticles, the peak concentration and AUC(0→12h) of sirolimus were increased by approximately 18.3-fold and 15.2-fold, respectively. The results of this study suggest that preparation of PVP K30-sirolimus-surfactant nanoparticles using the SAS process may be a promising approach for improving the bioavailability of sirolimus. Source

Keum C.G.,Chungnam National University
International journal of nanomedicine | Year: 2011

Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA), are the most intensively investigated polymers for drug delivery systems. The objective of this study was to explore fully the development of a PLGA nanoparticle drug delivery system for alternative preparation of a commercial formulation. In our nanoparticle fabrication, our purpose was to compare various preparation parameters. Docetaxel-loaded PLGA nanoparticles were prepared by a single emulsion technique and solvent evaporation. The nanoparticles were characterized by various techniques, including scanning electron microscopy for surface morphology, dynamic light scattering for size and zeta potential, x-ray photoelectron spectroscopy for surface chemistry, and high-performance liquid chromatography for in vitro drug release kinetics. To obtain a smaller particle, 0.2% polyvinyl alcohol, 0.03% D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), 2% Poloxamer 188, a five-minute sonication time, 130 W sonication power, evaporation with magnetic stirring, and centrifugation at 8000 rpm were selected. To increase encapsulation efficiency in the nanoparticles, certain factors were varied, ie, 2-5 minutes of sonication time, 70-130 W sonication power, and 5-25 mg drug loading. A five-minute sonication time, 130 W sonication power, and a 10 mg drug loading amount were selected. Under these conditions, the nanoparticles reached over 90% encapsulation efficiency. Release kinetics showed that 20.83%, 40.07%, and 51.5% of the docetaxel was released in 28 days from nanoparticles containing Poloxamer 188, TPGS, or polyvinyl alcohol, respectively. TPGS and Poloxamer 188 had slower release kinetics than polyvinyl alcohol. It was predicted that there was residual drug remaining on the surface from x-ray photoelectron spectroscopy. Our research shows that the choice of surfactant is important for controlled release of docetaxel. Source

Cho J.,Chungnam National University | Lazarian A.,University of Wisconsin - Madison
Astrophysical Journal | Year: 2014

When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfvénic MHD turbulence in the relativistic limit can be described by interactions of counter-traveling wave packets. In this paper, we numerically study strong imbalanced MHD turbulence in such environments. Here, imbalanced turbulence means the waves traveling in one direction (dominant waves) have higher amplitudes than the opposite-traveling waves (sub-dominant waves). We find that (1) spectrum of the dominant waves is steeper than that of sub-dominant waves, (2) the anisotropy of the dominant waves is weaker than that of sub-dominant waves, and (3) the dependence of the ratio of magnetic energy densities of dominant and sub-dominant waves on the ratio of energy injection rates is steeper than quadratic (i.e., with n > 2). These results are consistent with those obtained for imbalanced non-relativistic Alfvénic turbulence. This corresponds well to the earlier reported similarity of the relativistic and non-relativistic balanced magnetic turbulence. © 2014. The American Astronomical Society. All rights reserved. Source

Lee H.,Seoul National University | Lee S.,Chungnam National University | Cho I.-H.,Korea Institute of Oriental Medicine | Lee S.J.,Seoul National University
Current Protein and Peptide Science | Year: 2013

Toll-like receptors (TLRs) are type I transmembrane signaling molecules that are expressed in cells of the innate immune system. In these cells, TLRs function as pattern recognition receptors (PRR) that recognize specific molecular patterns derived from microorganisms. Upon activation, TLRs trigger a cascade of intracellular signaling pathways in innate immune cells, leading to the induction of inflammatory and innate immune responses, which in turn regulate adaptive immune responses. In the nervous system, different members of the TLR family are expressed on glial cells (astrocytes, microglia, oligodendrocytes, and Schwann cells) and neurons. Recently, increasing evidence has supported the idea that TLRs also recognize endogenous molecules that are released from damaged tissue, thereby regulating inflammatory responses and subsequent tissue repair. These findings imply that TLRs on glial cells may also be involved in the inflammatory response to tissue damage in the nervous system. In this review, we discuss recent studies on TLR expression in the cells of the nervous system and their roles in acute neurological disorders involving tissue damage such as strokes, traumatic spinal cord and brain injuries, and peripheral nerve injuries. © 2013 Bentham Science Publishers. Source

Lee C.-H.,Kongju National University | Jeong M.-K.,Kongju National University | Fatih Kilicaslan M.,Kastamonu University | Lee J.-H.,Chungnam National University | And 2 more authors.
Waste Management | Year: 2013

In this study, a method which is environmentally sound, time and energy efficient has been used for recovery of indium from used liquid crystal display (LCD) panels. In this method, indium tin oxide (ITO) glass was crushed to micron size particles in seconds via high energy ball milling (HEBM). The parameters affecting the amount of dissolved indium such as milling time, particle size, effect time of acid solution, amount of HCl in the acid solution were tried to be optimized. The results show that by crushing ITO glass to micron size particles by HEBM, it is possible to extract higher amount of indium at room temperature than that by conventional methods using only conventional shredding machines. In this study, 86% of indium which exists in raw materials was recovered about in a very short time. © 2012 Elsevier Ltd. Source

Choi J.H.,Chungnam National University
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association | Year: 2013

Ginseng contains many bioactive constituents, including various ginsenosides that are believed to have anti-allergic, anti-oxidant, and immunostimulatory activities; however, its effects on atopic dermatitis (AD) remain unclear. In the current study, we hypothesized that cultivated ginseng (CG) would inhibit 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in NC/Nga mice by regulating the T helper (Th)1/Th2 balance. Also, CG inhibits TNF-α/IFN-γ-induced thymus- and activation-regulated chemokine (TARC) expression through nuclear factor-kappa B (NF-κB)-dependent signaling in HaCaT cells. CG ameliorated DNCB-induced dermatitis severity, serum levels of IgE and TARC, and mRNA expression of TARC, TNF-α, IFN-γ, IL-4, IL-5, and IL-13 in mice. Histopathological examination showed reduced thickness of the epidermis/dermis and dermal infiltration of inflammatory cells in the ears. Furthermore, CG suppressed the TNF-α/IFN-γ-induced mRNA expression of TARC in HaCaT cells. CG inhibited TNF-α/IFN-γ-induced NF-κB activation. These results suggest that CG inhibited the development of the AD-like skin symptoms by modulating Th1 and Th2 responses in the skin lesions in mice and TARC expression by suppressing TNF-α/IFN-γ-induced NF-κB activation in keratinocytes, and so may be a useful tool in the therapy of AD-like skin symptoms. Copyright © 2013 Elsevier Ltd. All rights reserved. Source

Cho J.,Chungnam National University
Astrophysical Journal | Year: 2014

The origin of magnetic fields in galaxy clusters is still an unsolved problem that is largely due to our poor understanding of initial seed magnetic fields. If the seed magnetic fields have primordial origins, it is likely that large-scale pervasive magnetic fields were present before the formation of the large-scale structure. On the other hand, if they were ejected from astrophysical bodies, then they were highly localized in space at the time of injection. In this paper, using turbulence dynamo models for high magnetic Prandtl number fluids, we find constraints on the seed magnetic fields. The hydrodynamic Reynolds number based on the Spitzer viscosity in the intracluster medium (ICM) is believed to be less than O(102), while the magnetic Reynolds number can be much larger. In this case, if the seed magnetic fields have primordial origins, they should be stronger than O(10-11)G, which is very close to the upper limit of O(10-9)G set by the cosmic microwave background observations. On the other hand, if the seed magnetic fields were ejected from astrophysical bodies, any seed magnetic fields stronger than O(10-9)G can safely magnetize the ICM. Therefore, it is less likely that primordial magnetic fields are the direct origin of present-day magnetic fields in the ICM. © 2014. The American Astronomical Society. All rights reserved. Source

Frank J.H.,University of Florida | Ahn K.-J.,Chungnam National University
ZooKeys | Year: 2011

We provide a list of the 392 described species of Staphylinidae confined to coastal habitats worldwide. The list is in taxonomic sequence by subfamily, tribe, and genus and includes 91 genera. We provide the page reference of the original description of every species and genus listed and of many synonyms. We note the existence of recent reviews, phylogenies and keys of each of the tribes and genera included. Coastal Staphylinidae contain eight subfamilies: Microsilphinae, Omaliinae, Pselaphinae, Aleocharinae, Oxytelinae, Scydmaeninae, Paederinae, and Staphylininae. By 'coastal habitats' we mean habitats existing on the sea coast and subject to inundation or at least splashing by the very highest tides. This includes rocky, boulder, coral, sandy, and muddy seashores, and at least portions of salt-marshes, estuaries, and mangrove swamps. We exclude the sand dune habitat and higher parts of sea-cliffs. The list notes distribution of all the species, first according to the ocean or sea on whose shores it has been recorded, and second by country (and for the larger countries by province or state). Although this distribution is undoubtedly incomplete, it provides a basis for future development of a dedicated database. The 'Habitats, Habits, and Classificatory Notes' section is designed to provide ecologists with further taxonomic and ecological information. It includes references to descriptions of the immature stages, behavior of adults and immatures, their food, natural enemies, and habitat. We would have preferred to separate these entities, but current knowledge of ecology is developed in few instances beyond natural history. The Pacific Ocean basin was the origin and contributed to the dispersal of the majority of specialist coastal Staphylinidae at the level of genus. However, at the level of species, species belonging to noncoastal- specialist genera are about as likely to occur on the shores of other oceans as on the shores of the Pacific. This difference is a reflection of the antiquity of coastal genera and species. A complete bibliography, and habitat and habitus photographs of some representative coastal Staphylinidae species are provided. © J.H. Frank, K.-J. Ahn. Source

Ju Chae D.,Korea University | Yoon Kim D.,Korea University | Geun Kim T.,Korea University | Mo Sung Y.,Korea University | Doeck Kim M.,Chungnam National University
Applied Physics Letters | Year: 2012

In this paper, improved electrical and optical properties of aluminum gallium nitride (AlGaN)-based ultraviolet light-emitting diodes using fluorine-doped indium tin oxide (F-ITO) electrodes are reported. F-doping was found to increase the work function as well as the energy bandgap of the ITO and, thereby, reduce the Shottky barrier height in contact with p-(Al)GaN. As a result, the optical transmittance increased from 79.7 to 86.9 at 380 nm, while the specific contact resistance decreased from 1.04 10 -3 cm 2 to 9.12 10 -4 cm 2 after F-doping, which led to an increase in the output power from 2.41 mW to 5.99 mW. © 2012 American Institute of Physics. Source

Cho J.,Chungnam National University
Journal of the Korean Physical Society | Year: 2014

When the magnetic field is so strong that the magnetic energy density is much larger than that of matter, magnetic perturbations propagate along the magnetic field lines, and the speed of propagation approaches the speed of light. As in the non-relativistic case, counter-traveling waves in this relativistic limit can interact and generate turbulence. In the present paper, we discuss the properties of the magnetohydrodynamic (MHD) turbulence generated by such interactions. First, we discuss the scaling relations for driven, balanced, relativistic MHD turbulence, in which the amplitudes of counter-traveling wave packets are similar. Second, we discuss the scaling relations of imbalanced relativistic MHD turbulence, in which the amplitudes of counter-traveling wave packets are different. Numerical simulations show that the scaling relations of relativistic MHD turbulence for both cases are very similar to those for their non-relativistic counterparts. © 2014, The Korean Physical Society. Source

Kim S.,Chungnam National University | Cho S.,Anyang University, South Korea
Journal of the American Society for Information Science and Technology | Year: 2013

Korea, along with Asia at large, is producing more and more valuable academic materials. Furthermore, the demand for academic materials produced in non-Western societies is increasing among English-speaking users. In order to search among such material, users rely on keywords such as author names. However, Asian nations such as Korea and China have markedly different methods of writing personal names from Western naming traditions. Among these differences are name components, structure, writing customs, and distribution of surnames. These differences influence the Anglicization of Asian academic researchers' names, often leading to them being written in various fashions, unlike Western personal names. These inconsistent formats can often lead to difficulties in searching and finding academic materials for Western users unfamiliar with Korean and Asian personal names. This article presents methods for precisely understanding and categorizing Korean personal names in order to make academic materials by Korean authors easier to find for Westerners. As such, this article discusses characteristics particular to Korean personal names and furthermore analyzes how the personal names of Korean academic researchers are currently being written in English. © 2012 ASIS&T. Source

Sung Y.J.,Chungnam National University | Shin S.-J.,Chungbuk National University
Biomass and Bioenergy | Year: 2011

The effects of electron beam irradiation on chemical decomposition of industrial hemp biomass were evaluated at doses of 150, 300, and 450 kGy. The quantity of decomposed components was indirectly estimated by measuring changes in alkaline extraction. The more severe degradation of structural components induced by higher irradiation doses resulted in larger amounts of alkaline extract. Carbohydrate compositional analysis using 1H-NMR spectroscopy was applied to quantitatively investigate changes in the polysaccharides of the industrial hemp. The xylose peak intensity in the NMR spectra decreased with increasing electron irradiation dose, indicating that xylan was more sensitive to electron beam irradiation than cellulose. © 2011 Elsevier Ltd. Source

Park C.H.,Chungnam National University
Signal Processing | Year: 2014

Query by humming (QBH) is to retrieve songs in the music database by using user's humming. In QBH, the huge size of a song database requires an efficient search method. Recently, local sensitive hashing (LSH) has been applied in QBH and showed its superior performance. In this paper, we propose a method for QBH which uses multiple spectral hashing (MSH) and scaled open-end dynamic time warping (SOEDTW). We construct multiple binary embedding spaces by utilizing eigenvectors obtained from spectral hashing, so we call this approach as multiple spectral hashing (MSH). We also apply an improved OEDTW method for similarity matching. The experimental results demonstrate that the proposed method can improve retrieval performance greatly. © 2014 Elsevier B.V. All rights reserved. Source

Moon J.,Korea University | Lim N.-H.,Chungnam National University | Lee H.-E.,Korea University
Thin-Walled Structures | Year: 2013

Corrugated steel plates have several advantages such as high resistance for shear without stiffeners, minimization of welding process, and high fatigue resistance. To take advantage of these benefits, several researchers have attempted to use corrugated steel plate as a web for I-girders. The flexural- torsional buckling is the major design aspect of such I-girders. However, the flexural-torsional buckling of the I-girder with corrugated steel webs still needs to be investigated especially for a real loading condition such as non-uniform bending. This paper investigated the flexural-torsional buckling strength of an I-girder with corrugated steel webs under linear moment gradient by using finite element analysis. From the results, it was found that the buckling behavior of the I-girder with corrugated steel webs differed depending on the number of periods of the corrugation. Also, a simple equation for the moment gradient correction factor for the I-girder with corrugated steel webs was suggested. The inelastic flexural-torsional buckling strength of the I-girder with corrugated steel webs was then discussed based on current design equations for ordinary I-girders and inelastic finite element analysis considering initial imperfection and residual stresses. © 2012 Elsevier Ltd. All rights reserved. Source

A recent paper by H.-J. Kim, J.-H. Kim, C.S.S.P. Kumar, D. Punnoose, S.-K. Kim, C.V.V.M. Gopi, S.S. Rao [1] provides a facile chemical bath deposition of CuS nano peas like structure as a high efficient counter electrode for quantum-dot-sensitized solar cells, but makes an unjustified approximation in the film thickness. Herein, the film thickness was carefully analyzed again based on the original paper. © 2015 Elsevier B.V. Source

Hui C.-Y.,Chungnam National University
Journal of Astronomy and Space Science | Year: 2014

The nature of the exotic stellar corpses which reincarnate by consuming their companion is reviewed. Apart from sucking life from their partners, they are actually eating the doomed companions away by their deadly and powerful particle/radiation beams. Such situation resembles that a female "black widow" spider that eats its mate after mating. These celestial zombies are called - Millisecond pulsars (MSPs). In this review article, I will focus on the effort of Fermi Asian Network (FAN) in exploring these intricating objects over the last five years. Two special classes of MSPs are particularly striking. Since Fermi Gamma-ray Space Telescope has started surveying the gamma-ray sky, the population of "black widows" has been boosted. Another dramatic class is so-called "redbacks" (Australian cousin of "black widows") which has just emerged in the last few years. These MSPs provide us with a long-sought missing link in understanding the transition between accretion-powered and rotation-powered systems. The strategy of hunting MSPs through mulitwavelength observations of the unidentified Fermi objects is also reviewed. © The Korean Space Science Society. Source

Ahn K.-J.,Chungnam National University | Jeon M.-J.,National Institute of Biological Resources | Branham M.A.,University of Florida
Cladistics | Year: 2010

A phylogenetic analysis of the tribe Liparocephalini Fenyes is presented based on morphological and molecular characters. The data set comprised 50 adult morphological characters, partial COI (907 bp), COII (366 bp) and 12S rDNA (325-355 bp), and nearly complete sequences of 18S rDNA (1768-1902 bp) for 21 species. Eighteen species of liparocephaline beetles from all eight genera and three outgroups, are included. The sequences were analysed separately and simultaneously with morphological characters by direct optimization in the program POY4 and by partitioned Bayesian analysis for the combined data. The direct optimization (DO) tree for the combined data under equal weighting, which also shows a minimum incongruence length difference value, resulted in a monophyletic Liparocephalini with the following patterns of phylogenetic relationships (outgroup ((Baeostethus, Ianmoorea) (Paramblopusa ((Amblopusa, Halorhadinus) (Liparocephalus, Diaulota))))). A sensitivity analysis using 16 different parameter sets for the combined data shows the monophyly of the liparocephalines and all its genera under all parameter sets. Bayesian analysis resulted in topological differences in comparison with the DO tree under equal weighting only in the position of the genus Paramblopusa and clade (Amblopusa + Halorhadinus), which were reversed. Historical biogeography and the stepwise evolutionary colonization of intertidal habitat in the Liparocephalini are discussed. Based on the biogeographical analyses, we hypothesize that the ancestor of the Liparocephalini occurred along the Panthallassan Ocean, the direct antecedent of the Pacific Ocean, followed by repeated dispersals to the Nearctic from the Palearctic. We also hypothesize that ancestors of the Liparocephalini appear to have arisen in the littoral zone of beaches and then colonized rocky reef areas in the low tidal zone later through high- to mid-tide zones. © The Willi Hennig Society 2009. © The Willi Hennig Society 2009. Source

Kang E.-S.,Chungnam National University
Journal of Institute of Control, Robotics and Systems | Year: 2015

Although human-sized bipedal humanoid robots have been developed as the ideal form of human-friendly robots, studies of humanoid robots from the user perspective and of actual interaction between humanoid robots and the public in daily environments are few. This paper presents a long-term public demonstration that encouraged interaction between a humanoid robot and unspecified individuals. We have collected a significant amount of subjective evaluation data from the public by performing a storytelling demonstration that enhanced people's empathy towards the robot. The evaluation model consists of the robot's human friendliness, which involves its impression on humans, interaction with humans, and imitation of human motions and the robot's human appearance which involves gender, age, height, and body type. This study shows that there is no significant difference in human-friendliness between gender groups (male and female), while there is a significant difference between age groups (children and adults). In human appearance, it appears that there is no significant difference between either gender groups or age groups, except for the case of the robot's height. © ICROS 2015. Source

Song D.,Chungnam National University
NeuroQuantology | Year: 2014

Motivated by the fact that information is encoded and processed by physical systems, the P versus NP problem is examined in terms of physical processes. In particular, we consider P as a class of deterministic, and NP as nondeterministic, polynomial-time physical processes. Based on these identifications, we review a self-reference physical process in quantum theory, which belongs to NP but cannot be contained in P. © 2014, NeuroQuantology. All rights reserved. Source

Kang S.K.,Chungnam National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2013

In the title compound (systematic name: {[(phenylformamido)carbonyl]amino} methanethioamide), C9H9N3O2S, both benzoyl and terminal thiourea fragments adopt transoid conformations with respect to the central carbonyl O atom. The benzoyl and thiobiuret groups are almost coplanar, making a dihedral angle of 4.40 (8)°. The molecular structure is stabilized by two intramolecular N - H⋯O hydrogen bonds. In the crystal, N - H⋯O and N - H⋯S hydrogen bonds link the molecules into a tape running along [101]. Source

Lee H.-R.,Korea Institute of Machinery and Materials | Chung K.-Y.,Korea Institute of Machinery and Materials | Jhang K.-S.,Chungnam National University
Journal of Information Processing Systems | Year: 2013

Maintenance Access Hatches are used to ensure urban safety and aesthetics while facilitating the management of power lines, telecommunication lines, and gas pipes. Such facilities necessitate affordable and effective surveillance. In this paper, we propose a FiCHS (Fixed Cluster head centralized Hierarchical Static clustering) routing protocol that is suitable for underground maintenance hatches using WSN (Wireless Sensor Network) technology. FiCHS is compared with three other protocols, LEACH, LEACH-C, and a simplified LEACH, based on an ns-2 simulation. FiCHS was observed to exhibit the highest levels of power and data transfer efficiency. © 2013 KIPS. Source

Lim H.S.,Chungnam National University
Laser Therapy | Year: 2011

Background and Aims: This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. Materials and Methods: We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. Results and Comments: The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. Conclusions: The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes. © 2011 JMLL, Tokyo, Japan. Source

Jung S.,Chungnam National University
Journal of Intelligent and Robotic Systems: Theory and Applications | Year: 2014

This article presents the contact force control approach for a quad-rotor system to perform tasks of interacting with the environment. The hovering capability of the quad-rotor system allows the force in the altitude direction to be regulated by realizing the impedance function. To obtain the better force control performance, inherent and external disturbances to the quad-rotor system are suppressed by designing the acceleration-based disturbance observer (AbDOB). Force tracking impedance control is applied to regulate the contact force to the environment. Simulation studies of force tracking control for changing a light bulb on the ceiling are performed to evaluate the feasibility of the proposed force control task for a quad-rotor system. © Springer Science+Business Media Dordrecht 2013. Source

Oh S.Y.,University of Delaware | Yi Y.,Chungnam National University | Bieber J.W.,University of Delaware
Solar Physics | Year: 2010

The diurnal variation of the galactic cosmic ray (GCR) count rates measured by a ground-based neutron monitor (NM) station represents an anisotropic flow of GCR at 1 AU. The variation of the local time of GCR maximum intensity (we call the phase) is thought in general to have a period of two sunspot cycles (22 years). However, other interpretations are also possible. In order to determine the cyclic behavior of GCR anisotropic variation more precisely, we have carried out a statistical study on the diurnal variation of the phase. We examined 54-year data of Huancayo (Haleakala), 40-year data from Rome, and 43-year data from Oulu NM stations using the 'pile-up' method and the F-test. We found that the phase variation has two components: of 22-year and 11-year cycles. All NM stations show mainly the 22-year phase variation controlled by the drift effect due to solar polar magnetic field reversal, regardless of their latitudinal location (cut-off rigidity). However, the lower the NM station latitude is (the higher the cut-off rigidity is), the higher is the contribution from the 11-year phase variation controlled by the diffusion effect due to the change in strength of the interplanetary magnetic fields associated with the sunspot cycle. © 2010 Springer Science+Business Media B.V. Source

Tam P.H.T.,National Tsing Hua University | Kong A.K.H.,National Tsing Hua University | Hui C.Y.,Chungnam National University | Cheng K.S.,University of Hong Kong | And 2 more authors.
Astrophysical Journal | Year: 2011

Globular clusters (GCs) are emerging as a new class of γ-ray emitters, thanks to the data obtained from the Fermi Gamma-ray Space Telescope. By now, eight GCs are known to emit γ-rays at energies >100 MeV. Based on the stellar encounter rate of the GCs, we identify potential γ-ray emitting GCs out of all known GCs that have not been studied in detail before. In this paper, we report the discovery of a number of new γ-ray GCs: Liller 1, NGC6624, and NGC6752, and evidence of γ-ray emission from M80, NGC6139, and NGC6541, in which γ-rays were found within the GC tidal radius. With one of the highest metallicities among all GCs in the Milky Way, the γ-ray luminosity of Liller 1 is found to be the highest of all known γ-ray GCs. In addition, we confirm a previous report of a significant γ-ray emitting region next to NGC6441. We briefly discuss the observed offset of γ-rays from some GC cores. The increasing number of known γ-ray GCs at distances out to 10 kpc is important for us to understand the γ-ray emitting mechanism and provides an alternative probe to the underlying millisecond pulsar populations of the GCs. © 2011. The American Astronomical Society. All rights reserved. Source

Yao L.,Tulane University | Han C.,Tulane University | Song K.,Tulane University | Zhang J.,Tulane University | And 2 more authors.
Cancer Research | Year: 2015

Prostaglandin E2 (PGE2) is a proinflammatory lipid mediator that promotes cancer growth. The 15-hydroxyprostaglandin dehydrogenase (15-PGDH) catalyzes oxidation of the 15(S)-hydroxyl group of PGE2, leading to its inactivation. Therefore, 15-PGDH induction may offer a strategy to treat cancers that are driven by PGE2, such as human cholangiocarcinoma. Here, we report that omega-3 polyunsaturated fatty acids (ω-3 PUFA) upregulate 15-PGDH expression by inhibiting miR-26a and miR-26b, thereby contributing to ω-3 PUFA-induced inhibition of human cholangiocarcinoma cell growth. Treatment of human cholangiocarcinoma cells (CCLP1 and TFK-1) with ω-3 PUFA (DHA) or transfection of these cells with the Fat-1 gene (encoding Caenorhabditis elegans desaturase, which converts ω-6 PUFA to ω-3 PUFA) significantly increased 15-PGDH enzymes levels, but with little effect on the activity of the 15-PGDH gene promoter. Mechanistic investigations revealed that this increase in 15-PGDH levels in cells was mediated by a reduction in the expression of miR-26aandmiR-26b, which target 15-PGDH mRNA and inhibit 15-PGDH translation. These findings were extended by the demonstration that overexpressing miR-26a or miR-26b decreased 15-PGDH protein levels, reversed ω-3 PUFA-induced accumulation of 15-PGDH protein, and prevented ω-3 PUFA-induced inhibition of cholangiocarcinoma cell growth. We further observed that ω-3 PUFA suppressed miR-26a and miR-26b by inhibiting c-myc, a transcription factor that regulates miR-26a/b. Accordingly, c-myc overexpression enhanced expression of miR-26a/b and ablated the ability of ω-3 PUFA to inhibit cell growth. Taken together, our results reveal a novel mechanism for ω-3 PUFA-induced expression of 15-PGDH in human cholangiocarcinoma and provide a preclinical rationale for the evaluation of ω-3 PUFA in treatment of this malignancy. © 2015 American Association for Cancer Research. Source

Park S.I.,Electronics and Telecommunications Research Institute | Lim H.,Electronics and Telecommunications Research Institute | Kim H.M.,Electronics and Telecommunications Research Institute | Wu Y.,Communications Research Center Canada | Oh W.,Chungnam National University
IEEE Transactions on Broadcasting | Year: 2012

In this paper, we propose a novel Augmented Data Transmission (ADT) system which can transmit an additional data stream in the Advanced Television Systems Committee (ATSC) terrestrial DTV system. The proposed ADT system can offer an additional data of rate up to a few megabits per second (Mbps) based on hierarchical modulation, DTV signal cancellation, and advanced error correction code. The proposed ADT system significantly enhances capability compared with the data transmission schemes used in the transmitter identification (TxID) system. Since the proposed ADT system uses the in-band hierarchical modulation, it does not require any additional RF spectrum to increase the data capacity in a 6 MHz RF channel. Meanwhile, the ADT system has negligible impact to legacy receivers, if the proposed ADT system is deployed over the frequency bands occupied by ATSC A/53 or A/153 services. © 2012 IEEE. Source

Ko H.,Sogang University | Lee J.,Sogang University | Kim Y.,Sogang University | Lee B.,Sogang University | And 5 more authors.
Advanced Materials | Year: 2014

Active, paper-based, microfluidic chips driven by electrowetting are fabricated and demonstrated for reagent transport and mixing. Instead of using the passive capillary force on the pulp to actuate a flow of a liquid, a group of digital drops are transported along programmed trajectories above the electrodes printed on low-cost paper, which should allow point-of-care production and diagnostic activities in the future. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kim M.R.,Kongju National University | Lim Y.T.,Chungnam National University | Cho K.Y.,Kongju National University
Macromolecular Rapid Communications | Year: 2013

Fabrication of physically engineered colloids and their application to the biological fields is emerging importance because of their potential to provide an enhanced performance without altering the chemical properties of biomaterials used. A facile approach is reported to fabricate sub-10-μm-sized PLGA microparticle with small dimples covering the surface by droplet imprinting. Optical and magnetic resonance bioimaging agents are easily co-encapsulated inside the microparticles to obtain a bi-modal imaging agent. Cell internalization efficacy of dimpled particles in DC 2.4 cell is enhanced compared with conventional smooth round-shaped colloids. Our result indicates that morphology-controlled microparticles show promise as a cell labeling with improved cell interaction. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Lee J.-W.,Chungnam National University | Park C.-M.,Chonbuk National University | Rhee H.,University of Montana
Land Degradation and Development | Year: 2013

Decomposed granite roadcuts are difficult to revegetate after losing the topsoil and vegetation cover. We developed a new drilling machine, Digger, to efficiently drill six holes simultaneously on decomposed granite roadcuts to facilitate revegetation. The Digger consists of a base machine (0.7m3-level excavator) and a mounting body with six hydraulic motors instead of a bucket. We tested its performance on two roadcuts in southwest Korea using time-motion studies, which showed that the Digger can drill 240m2 of decomposed granite roadcuts daily. The unit cost of the Digger was less than a half of other roadcut stabilization and revegetation techniques in Korea, making the Digger a cost-effective revegetation technology. Field germination and growth tests were also conducted to identify appropriate diameter and depth of drilling holes, suitable revegetation species, and mulching treatment. We drilled holes with three different diameters and depths, filled the holes with a mixture of plant seeds and cultivated soil, applied mulching treatments (coir geotextile, shade net, and no mulching), and measured the germination and growth results at two field plots after 1month and 1year. The results showed that drilling diameter 10cm and depth 10cm were large enough to result in better plant germination and growth. Erosion control species, Poa pratensis L. and Eragrostis curvula (Schrad.) Nees, survived and grew better than native woody species. Coir geotextile improved the plant germination and growth. The time-motion and revegetation results show that the Digger can be a promising technology to restore decomposed granite roadcuts. © 2013 John Wiley & Sons, Ltd. Source

Choi J.M.,Chungnam National University | Lee C.W.,North Dakota State University
Journal of Plant Nutrition | Year: 2012

The relationship between the total amount of micronutrients absorbed by the above-ground plant tissue and the occurrence of visible micronutrient deficiency symptoms in two strawberry cultivars as influenced by elevated phosphorus (P) levels in fertigation solution was investigated. The plants were cultured with a fertilizer solution containing 0, 0.5, 1, 2, 4, or 6 mM P and tissue nutrient content were determined at 120 days after transplanting. Young leaves of the plants grown with nutrient solution P levels higher than 4 mM and 2 mM, respectively, in 'Keumhyang' and 'Seonhong', developed interveinal chlorosis. Tissue concentrations (mg·kg-1 dry weight) of metallic micronutrients [iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn)] in both cultivars did not decrease, but the total amount absorbed by the aboveground plant tissue decreased in the treatments in which nutrient deficiencies were observed. These results indicate that total amount of micronutrients is a better indicator of P-induced micronutrient deficiency. © 2012 Copyright Taylor and Francis Group, LLC. Source

Choi H.-B.,Chungnam National University | Konno A.,Tohoku University | Uchiyama M.,Tohoku University
Robotica | Year: 2010

This paper deals with the design, implementation, and performance evaluation of a new type of 4-DOF parallel mechanism providing three translations and one rotation for high-speed handling and machining. This parallel mechanism is named H4. A necessary condition and system configuration of the H4 are also described. Hardware and kinematics of the H4 is addressed and the manipulability ellipsoid which is one of the widely used methods to examine the design of parallel mechanisms is addressed. The performance evaluation is carried out to demonstrate the H4 robot. The simulation and experimental results show that three different controllers, the PD, PD + velocity feed-forward, and dynamic compensation controller, dramatically improve the trajectory tracking accuracy. © 2009 Cambridge University Press. Source

Noh Y.-W.,Korea Research Institute of Bioscience and Biotechnology | Noh Y.-W.,Chonbuk National University | Jang Y.-S.,Chonbuk National University | Ahn K.-J.,Catholic University of Korea | And 2 more authors.
Biomaterials | Year: 2011

We report the fabrication of a one-pot antigen system that delivers antigen to dendritic cells (DCs) and tracks their in vivo migration after injection. Multifunctional polymer nanoparticles containing ovalbumin protein, magnetic resonance imaging contrast agents (iron oxide nanoparticles), and near-infrared fluorophores (indocyanine green, ICG), MPN-OVA, were prepared using a double emulsion method. The MPN-OVA was efficiently taken up by the dendritic cells and subsequently localized in the lysosome. Flow cytometry analysis revealed an increase in the uptake of OVA antigen by MPN-OVA at 37 °C, when compared with soluble OVA protein. We found that MPN-OVA had no effect on DC surface expression of MHC class I, costimulatory (CD80, CD86) or adhesion (CD54) molecules or the ability of DCs to mature in response to LPS. Following the uptake of MPN-OVA, exogenous OVA antigen was delivered to the cytoplasm, and OVA peptides were presented on MHC class I molecules, which enhanced OVA antigen-specific cross-presentation to OT-1 T cells and CD8OVA1.3 T cell hybridoma in vitro. The immunization of mice with MPN-OVA-treated DCs induced OVA-specific CTL activity in draining lymph nodes. The presence of MPN allowed us to monitor the migration of DCs via lymphatic drainage using NIR fluorescence imaging, and the homing of DCs into the lymph nodes was imaged using MRI. This system has potential for use as a delivery system to induce T cell priming and to image DC-based immunotherapies. © 2011 Elsevier Ltd. Source

Kang H.,Pusan National University | Ryu D.,Chungnam National University
Astrophysical Journal | Year: 2011

We examine diffusive shock acceleration (DSA) of the pre-existing as well as freshly injected populations of non-thermal, cosmic-ray (CR) particles at weak cosmological shocks. Assuming simple models for thermal leakage injection and Alfvénic drift, we derive analytic, time-dependent solutions for the two populations of CRs accelerated in the test-particle regime. We then compare them with the results from kinetic DSA simulations for shock waves that are expected to form in intracluster media and cluster outskirts in the course of large-scale structure formation. We show that the test-particle solutions provide a good approximation for the pressure and spectrum of CRs accelerated at these weak shocks. Since the injection is extremely inefficient at weak shocks, the pre-existing CR population dominates over the injected population. If the pressure due to pre-existing CR protons is about 5% of the gas thermal pressure in the upstream flow, the downstream CR pressure can absorb typically a few to 10% of the shock ram pressure at shocks with a Mach number M ≲ 3, yet the re-acceleration of CR electrons can result in a substantial synchrotron emission behind the shock. The enhancement in synchrotron radiation across the shock is estimated to be about a few to several for M ∼ 1.5 and 10 2-103 for M ∼ 3, depending on the detail model parameters. The implication of our findings for observed bright radio relics is discussed. © 2011. The American Astronomical Society. All rights reserved. Source

Xu B.,Hong Kong Baptist University | Sung C.,Chungnam National University
Food Bioscience | Year: 2015

The objectives of current study were to find the potential telomerase inhibitors from spices and to investigate their anticancer properties. The in vitro inhibitory effects of 28 spices against telomerase activity of HL-60 cells were systematically studied using polymerase chain reaction (PCR) based telomeric repeat amplification protocol, the PCR products were determined using native polyacrylamide gel electrophoresis. Telomerase inhibitory activity was evaluated by comparing DNA ladders. Telomerase inhibitory samples were further tested for anti-proliferation effects against gastric cancer cells SNU-1 using MTT assay. Hexane extract of onion, hexane extract of chili, ethyl acetate extract of chili, water extract of chili, and water extract of parsley exhibited strong telomerase inhibiting activity at the concentration of 10 μg/mL. Further anti-proliferation study indicated that hexane and ethyl acetate extracts of onion and ethyl acetate extract of chili at the concentration of 10 μg/mL showed 51.9%, 43.7% and 22.2% inhibitory rate against gastric cancer cells SNU-1, respectively; while the water extracts of chili and parsley did not show cancer cell proliferation inhibitory effect. The hexane extract of onion exhibited both telomerase inhibitory effect and cancer cell proliferation inhibitory effect with IC50 value at 14.18 μg/mL. Onion deserves to be further studied, it has a potential to be developed into an anticancer agent targeted on telomerase. © 2015 Elsevier Ltd. All rights reserved. Source

Park J.,Queens University | Sung N.-D.,Chungnam National University
Bulletin of the Korean Chemical Society | Year: 2011

Three dimensional quantitative structure-activity relationships (3D-QSARs) between new thiosemicarbazone analogues (1-31) as a substrate molecule and their inhibitory activity against tyrosinase as a receptor were performed and discussed quantitatively using CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) methods. According to the optimized CoMSIA 2 model obtained from the above procedure, inhibitory activities were mainly dependent upon H-bond acceptor favored field (36.5%) of substrate molecules. The optimized CoMSIA 2 model, with the sensitivity of the perturbation and the prediction, produced by a progressive scrambling analysis was not dependent on chance correlation. From molecular docking studies, it is supposed that the inhibitory activation of the substrate molecules against tyrosinase (PDB code: 1WX2) would not take place via uncompetitive inhibition forming a chelate between copper atoms in the active site of tyrosinase and thiosemicarbazone moieties of the substrate molecules, but via competitive inhibition based on H-bonding. Source

Kang E.G.,Wonkwang University | Jeon S.J.,Wonkwang University | Choi S.S.,Wonkwang University | Song C.J.,Chungnam National University | Yu I.K.,Eulji University
American Journal of Neuroradiology | Year: 2010

BACKGROUND AND PURPOSE: MR imaging features of HE have not been fully established. The purpose of this study was to determine the topographic distribution and DWI findings of HE. MATERIALS AND METHODS: We retrospectively evaluated HE MR imaging (n = 11). The topographic distribution of the lesions was evaluated on routine MR imaging, and DWI SI and ADC values were assessed. The ADC value of involved lesions was compared with the noninvolved subcorticalWMarea by use of the paired t test. RESULTS: MR images demonstrated bilateral diffusion-restrictive lesions in the posterior limb of the IC (n = 6), cerebral cortex (n = 8), CR (n = 7), CS (n = 9), hippocampus (n = 4), and BG (n = 1). The mean ADC value of lesions was 448.82 ± 92.34 × 10 -6 mm2/s compared with the mean ADC value of noninvolved lesions (837.72 ± 62.14 × 10-6 mm2/s); this difference was statistically significant (P < .000). The lesions showed complete resolution on follow-up DWI for 6 patients. Three patients with cortical involvement of ≥2 lobes showed partial recovery or death, but most of the other patients with WM involvement or cortical involvement in only 1 lobe experienced complete recovery. CONCLUSIONS: The topographic localization of the lesions was the posterior limb of the IC, cerebral cortex, CR, CS, hippocampus, and BG. Most HE lesions probably correspond to areas of reversible cytotoxic edema as seen on DWI, which can predict the prognosis of HE according to the degree of lesion extent. Source

Jo E.-K.,6 Munhwa dong | Jo E.-K.,Chungnam National University
Cellular Microbiology | Year: 2010

Summary: Autophagy is an ancient mechanism of protein degradation and a novel antimicrobial strategy. With respect to host defences against mycobacteria, autophagy plays a crucial role in antimycobacterial resistance, and contributes to immune surveillance of intracellular pathogens and vaccine efficacy. Vitamin D3 contributes to host immune responses against Mycobacterium tuberculosis through LL-37/hCAP-18, which is the only cathelicidin identified to date in humans. In this review, we discuss recent advances in our understanding of host immune strategies against mycobacteria, including vitamin D-mediated innate immunity and autophagy activation. This review also addresses our current understanding regarding the autophagy connection to principal innate machinery, such as ubiquitin- or inflammasome-involved pathways. Integrated dialog between autophagy and innate immunity may contribute to adequate host immune defences against mycobacterial infection. © 2010 Blackwell Publishing Ltd. Source

Jeong G.Y.,Andong National University | Jeong G.Y.,Chungnam National University | Lee K.-S.,Korea Basic Science Institute
American Mineralogist | Year: 2010

The most important terrestrial archive of the Quaternary climate is the Chinese Loess Plateau (CLP) distributed over a. vast region peripheral to the deserts of Inner Asia. Numerous paleoclimatic studies have examined magnetic, chemical, and isotopic proxies from deep loess-paleosol sections. However, the highly uniform mineralogy of the CLP has made it difficult to track the provenance, transportation, and deposition of dust particles. Here, we report that the micrometer-scale mineralogical heterogeneity of the loess particles has a significant potential in determining high-resolution loess provenance. Scanning and transmission electron microscopy of the Chinese loess reveals that biotite particles commonly have microinclusions of Ba-Sr sulfates displacing the micaceous layers along cleavages. Chemical compositions varied widely from barite to celestine within the same biotite grain. The Ba.-rich sulfates precipitated first, followed by an overgrowth of Sr-rich sulfates. The frequency of sulfate-bearing biotite varied greatly over several loess sections, implying a specific source and sedimentation process. Their abundance on the western CLP and sulfur isotopic composition support their derivation from porous sedimentary sequences reacted with hypersaline solutions, e.g., arkosic sandstone, probably located west of the CLP covering the Qilian Mountains, Qaidam Basin, and surrounding mountains of the Tibetan-Qinghai Plateau. The sulfate-bearing biotite is the first microscopic mineral tracer in the CLP, provoking further search for other microscopic heterogeneities of the Chinese loess and their equivalents in the source regions. Source

Sharma M.,Korea Institute of Energy Research | Sharma P.,Chungnam National University | Kim J.N.,Korea Institute of Energy Research
RSC Advances | Year: 2013

To chase the environmental regulations regarding the quality of fuels the global society calls for zero sulfur fuels. Therefore, the issue of the removal of aromatics from fuels has become more serious because the existence of aromatics in fuel hinders the production of ultra-low sulfur fuel. It creates an enormous interest amongst the scientific community worldwide in research involving the dearomatization of fuels. The present perspective review discusses the need for dearomatization, the concepts, advantages and disadvantages of various processes used for dearomatization together with advances in the dearomatization of hydrocarbon fuels, more specifically of diesel fractions by solvent extraction. The more challenging task required for the dearomatization of diesel fractions by solvent extraction is the selection of a proper solvent along with the optimum extraction conditions. This review reveals key solvents and extraction conditions influencing the removal of aromatic components from petroleum derived fractions. In addition, it demonstrates the dependence of solvent selection criteria on the properties and boiling range of the feedstock. It also demonstrates that each of the solvents used offers some advantages and disadvantages from a techno-economic point of view irrespective of the solvents used in a particular process. © The Royal Society of Chemistry 2013. Source

Jeong S.-H.,Chungnam National University | Kim H.-J.,Seoul National University | Kim J.-S.,Seoul National University
Seminars in Neurology | Year: 2013

Vestibular neuritis is the most common cause of acute spontaneous vertigo. Vestibular neuritis is ascribed to acute unilateral loss of vestibular function, probably due to reactivation of herpes simplex virus in the vestibular ganglia. The diagnostic hallmarks of vestibular neuritis are spontaneous horizontal-torsional nystagmus beating away from the lesion side, abnormal head impulse test for the involved semicircular canals, ipsilesional caloric paresis, decreased responses of vestibular-evoked myogenic potentials during stimulation of the affected ear, and unsteadiness with a falling tendency toward the lesion side. Vestibular neuritis preferentially involves the superior vestibular labyrinth and its afferents. Accordingly, the function of the posterior semicircular canal and saccule, which constitute the inferior vestibular labyrinth, is mostly spared in vestibular neuritis. However, because the rare subtype of inferior vestibular neuritis lacks the typical features of vestibular neuritis, it may be misdiagnosed as a central vestibular disorder. Even in the patient with the typical pattern of spontaneous nystagmus observed in vestibular neuritis, brain imaging is indicated when the patient has unprecedented headache, negative head impulse test, severe unsteadiness, or no recovery within 1 to 2 days. Symptomatic medication is indicated only during the acute phase to relieve the vertigo and nausea/vomiting. Vestibular rehabilitation hastens the recovery. The efficacy of topical and systemic steroids requires further validation. Copyright © 2013 by Thieme Medical Publishers, Inc. Source

Das P.K.,Chungnam National University
Molecules and cells | Year: 2012

Anthocyanins, a class of flavonoids, are recognized for their diverse functions in plant development and beneficial effects on human health. Many of the genes encoding anthocyanin biosynthesis enzymes and the transcription factors that activate or repress them have been identified. Regulatory proteins that control anthocyanin biosynthesis by regulating the expression of different structural genes at the transcriptional and post-transcriptional levels are differentially modulated by environmental and biological factors such as light, temperature, sugar and hormones. This minireview summarizes the recent findings contributing to our understanding of the role of sugars and hormones in the modulation of the anthocyanin biosynthesis pathway with emphasis on the coordinated regulation of the critical transcriptional R2R3-MYB/bHLH/WD40 (MBW) complex in Arabidopsis. Source

Han N.S.,Chungbuk National University | Kim T.-J.,Chungbuk National University | Park Y.-C.,Kookmin University | Kim J.,Chungnam National University | Seo J.-H.,Seoul National University
Biotechnology Advances | Year: 2012

Human milk contains a large variety of oligosaccharides (HMOs) that have the potential to modulate the gut flora, affect different gastrointestinal functions, and influence inflammatory processes. This review introduces the recent advances in the microbial and coupled enzymatic methods to produce HMOs with grouping them into trisaccharides (sialyllactose and fucosyllactose) and complex oligosaccharides (lacto- N-biose derivatives). The high purity and low cost of HMOs should make their use possible in new fields such as the food or pharmaceutical industries. © 2011 Elsevier Inc. Source

Lee H.,Dankook University | Choi J.S.,Chungnam National University | Larson R.G.,University of Michigan
Macromolecules | Year: 2011

G4 PAMAM dendrimers with each of the 64 termini grafted with zero to three histidine (His) residues followed by an end-grafted arginine (Arg) were simulated at two levels of protonation to mimic their electrostatic charges at pH 5 and 7. Arg is cationic at both pH values, and His is cationic only at pH 5. The simulations were carried out with a coarse-grained (CG) dendrimer force field that had previously predicted sizes and pH-dependent transitions between dense-core and dense-shell structures that were in agreement with experiments and all-atom simulations. In the work reported here, conjugation with Arg alone slightly increases the size of the dendrimer-conjugate complex at both pH 5 and 7 relative to that of the unmodified G4 dendrimer. Additional conjugation with His (pKa of ∼6.0), and with Arg again at the dendrimer terminals, does not change the complex size at pH 7 (at which His is neutral) relative to that with Arg alone, but at pH 5 (at which His is cationic), the addition of His does increase dendrimer size, showing that increased charge increases dendrimer swelling. The increased size may increase the cytotoxicity of the dendrimer at pH 5. Also, His conjugation induces a dense-core structure at pH 7 but does not change the dense-shell structure already present at pH 5 in the G4 dendrimer without amino acid conjugation. This indicates that the conjugation of His residues densifies the inner cavity of the dendrimer core at pH 7, leaving less room for other agents, and thus likely to lower drug encapsulation efficiency. These simulations suggest important possible effects of peptide conjugation on cytotoxicity and encapsulation efficiency at different pH, which need to be confirmed by experiments. © 2011 American Chemical Society. Source

Iwase T.,Johns Hopkins University | Nishi Y.,University of Tokyo | Jo Y.-J.,Chungnam National University
Journal of Cataract and Refractive Surgery | Year: 2011

Purpose: To evaluate posterior capsule opacification (PCO) 2 years after cataract surgery with implantation of a hydrophobic acrylic or single-piece sharp-edged hydrophilic acrylic intraocular lens (IOL). Setting: Toyama Prefectural Central Hospital, Toyama, Japan. Design: Case-control study. Methods: Patients with bilateral senile cataract were prospectively randomized to receive a hydrophobic IOL (Acrysof SA60AT) in 1 eye and a hydrophilic IOL (Meridian HP60M) in the other eye. The PCO density value, degree of IOL decentration and tilt, and anterior chamber depth (ACD) were measured using Scheimpflug videophotography 1, 6, 12, 18, and 24 months after surgery. Visual acuity and the number of eyes requiring neodymium:YAG laser capsulotomy were also assessed. Results: The study evaluated 16 eyes (63 patients). The PCO value in the hydrophilic group increased significantly with time and was statistically significantly greater than in the hydrophobic group 18 and 24 months postoperatively (both P<.001). The capsulotomy rate was statistically significantly higher in the hydrophilic group than in the hydrophobic group (P<.01). Visual acuity in the hydrophilic group worsened significantly with time and was statistically significantly worse than in the hydrophobic group at 18 and 24 months (both P<.001). Intraocular lens decentration, IOL tilt, and the ACD did not change significantly during the follow-up in either group (P>.05), and there were no statistically significant postoperative differences in these parameters between the 2 IOL groups (P>.05). Conclusion: Two years after surgery, the hydrophobic IOL group had less PCO, a lower capsulotomy rate, and better visual acuity than the hydrophilic IOL group. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. © 2011 ASCRS and ESCRS. Source

Ryu S.,Korea Atomic Energy Research Institute | Ko S.,Chungnam National University
Nuclear Engineering and Design | Year: 2012

The free energy based multiphase lattice Boltzmann method was used to directly simulate nucleate pool boiling. The interface capturing and energy equations with a phase change model were implemented into the isothermal lattice Boltzmann method. In order to validate the method, a bubble growth in a superheated liquid was simulated and compared to analytical solutions. Bubble departure diameter is dependent on gravity force, surface tension, contact angle, and wall superheat. Varying these parameters, numerical simulations were executed and the results were found to be in good agreement with the previous correlations. For a single nucleation site, the bubble growth on and departure from a superheated wall were simulated successfully. The vapor bubble shape and temperature fields were then compared to the experimental measurements. Also, for multiple nucleation sites, simulations were performed and their subsequent results are presented. The heat transfer rates of these simulations were calculated and compared to the empirical correlations for the nucleate pool boiling. Consequently, the multiphase lattice Boltzmann method with a phase change model is feasible for the direct numerical simulation of nucleate pool boiling. © 2012 Elsevier B.V. All rights reserved. Source

Shin J.H.,Seoul National University | Park J.S.,Chungnam National University | Son J.E.,Seoul National University
Agricultural Water Management | Year: 2014

Water management directly affects the productivity of paprika plants and is currently determined based on accumulated radiation levels. However, the amount of water used by the plants, which can be determined by their transpiration rates, does not always increase proportionally to the accumulated radiation levels, depending on the region and climate as well as crop growth stages and development. This effect is observed because the transpiration rate is also related to light intensity, which varies with the time of day and season. To develop a more efficient irrigation strategy, both factors should be analyzed based on the relationship between light intensity and transpiration rate in the short-term. In this study, a sigmoidal relationship between light intensity and transpiration rate at an interval of 10. min was observed using a consecutive transpiration monitoring system. From this relationship, a compensated equation that can calibrate the light intensity was developed. When a modified irrigation was applied using this compensated equation, less water was used compared to a conventional irrigation that supplies water proportional to accumulated radiation, especially in summer. Moreover, there were no significant differences in the transpiration rates and plant growth between plants watered with either the conventional or modified with compensated equation irrigation method. From these results, it was concluded that water was used more efficiently with the modified irrigation method without affecting plant growth. In a region with a high solar radiation in summer, such as Korea, using our equation to calculate for light intensity can prevent water waste, resulting in energy-saving and a reduction of environmental pollution in open-loop soilless cultures. © 2013 Elsevier B.V. Source

Miesch C.,University of Massachusetts Amherst | Kosif I.,University of Massachusetts Amherst | Lee E.,Chungnam National University | Kim J.-K.,University of Massachusetts Amherst | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2012

Stable double emulsions, both oil-in-water-in-oil and water-in-oil-in- water, stabilized by two types of nanoparticles residing at the o/w interfaces (see picture; red: CdSe quantum dots) were prepared in a simple fashion by shaking, and with narrow size distributions by microcapillary flow focusing. These double-emulsion droplets proved stable against coalescence throughout solvent evaporation, allowing for formation of nanoparticle foams and hexagonally arrayed structures. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kang M.S.,Gachon University | Lyou J.,Chungnam National University | Lee J.K.,Korea Atomic Energy Research Institute
Mechatronics | Year: 2010

This paper describes the application of an active magnetic bearing (AMB) system to levitate the elevation axis of an electro-optical sight mounted on a moving vehicle. In this type of system, it is desirable to retain the elevation axis in an air-gap between magnetic bearing stators while the vehicle is moving. A sliding mode control is applied to increase robustness to model uncertainties and to reduce disturbance responses. To ensure the authority of sliding mode control, model parameter uncertainties of AMB systems are analysed and reachability to sliding surface has been verified. The sliding surfaces are designed such that the poles of the closed-loop system locate at desired locations. The proposed control is applied to a 2-DOF active magnetic bearing system subject to base motion. The feasibility of the proposed technique is verified with experimental results. © 2009 Elsevier Ltd. All rights reserved. Source

Kim T.,Seoul National University | Hong J.,Seoul National University of Science and Technology | Koo H.,Chungnam National University
Industrial Management and Data Systems | Year: 2013

Purpose - The purpose of this study is to propose a systematic method for the diffusion of forecasting technology in the pre-launch stage. Design/methodology/approach - The authors designed survey question items that are familiar to interviewees as well as algebraically transformable into the parameters of a logistic diffusion model. In addition, they developed a procedure that reduces inconsistency in interviewee responses, removes outliers, and verifies conformability, in order to reduce the error and yield robust estimation results. Findings - The results show that the authors' method performed better in the empirical cases of digital media broadcasting and internet protocol television in terms of sum of squared error compared with an existing survey-based method, a regression method, and the guessing-by-analogy method. Specifically, the authors' method can reduce the error by using the conformability and outlier tests, while the consistency factor contributes to determining the final estimate with personal estimates. Research limitations/implications - The procedure proposed in this study is confined to the presented logistic model. Future research should aim to extend its application to other representative diffusion models such as the Bass model and the Gompertz model. Practical implications - The authors' method provides a better quality of forecasting for innovative new products and services compared with the guessing-by-analogy method, and it contributes to managerial decisions such as those in production planning. Originality/value - The authors introduce the concepts of conformability and consistency in order to reduce the error from personal biases and mistakes. Based on these concepts, they develop a procedure to yield robust estimation results with less error. © Emerald Group Publishing Limited. Source

Ha N.-Y.,Seoul National University | Cho N.-H.,Seoul National University | Kim Y.-S.,Chungnam National University | Choi M.-S.,Seoul National University | Kim I.-S.,Seoul National University
Infection and Immunity | Year: 2011

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular pathogen whose mechanism of cellular adhesion and invasion is poorly characterized. Bioinformatic analyses of two O. tsutsugamushi genomes revealed the presence of a group of genes that encode autotransporter proteins. In this study, we identified 10 autotransporter gene products and categorized them into five groups of orthologs (ScaA to ScaE) based on their sequence similarities. Sequence homology was highest between members of ScaC group, suggesting the functional conservation of bacterium-host interactions. ScaC was actively expressed on the surface of O. tsutsugamushi and induced antibody responses in scrub typhus patients. Experiments using microbeads conjugated to recombinant ScaC or a surrogate Escherichia coli expression system showed that ScaC was sufficient to mediate attachment to, but not invasion of, nonphagocytic mammalian cells. In addition, preincubation of host cells with recombinant ScaC significantly inhibited their interaction with O. tsutsugamushi. Finally, fibronectin was identified as a potential receptor for ScaC by using yeast two-hybrid screening, and this was confirmed using a glutathione S-transferase (GST) pulldown assay. Taken together, these results demonstrate that ScaC is involved in the interaction of O. tsutsugamushi with mammalian host cells and suggest that ScaC may play a critical role in bacterial pathogenesis. © 2011, American Society for Microbiology. Source

In this study, the influence of rapid freezing and thawing actions on mechanical properties of hybrid fibers reinforced strain-hardening cement-based composites (SHCCs), which exhibit multiple cracking and strain-hardening behavior in direct tension, were investigated. Four SHCC mixtures with different water-to-binder (W/B) ratios and hybrid fiber combinations were assessed experimentally. The SHCC mixtures incorporating hybrid polyvinyl alcohol (PVA) and ultra-high molecular weight polyethylene (PE) fibers at the 1.5% volume fraction were exposed to freezing and thawing according to ASTM C 666 (Procedure B). The freeze-thaw tests continued until the specimens achieved 300 freeze-thaw cycles. The results of these tests indicate that rapid freeze-thaw cycles in the laboratory have little effect on the compressive and tensile strength characteristics of the SHCC mixtures prepared in this study, whereas multiple cracking behavior and deformation capacity of SHCC specimens under direct tensile and flexural loadings indicate that freeze-thaw cycles have a negative effect on the these characteristics of the SHCC mixtures. A tendency toward reduced ductility is prominent for SHCC materials with higher W/B ratio and more hydrophilic PVA fiber. © 2013 Elsevier Ltd. All rights reserved. Source

Noh S.R.,Chungnam National University | Isaacowitz D.M.,Northeastern University
Psychology and Aging | Year: 2015

Despite many studies on the age-related positivity effect and its role in visual attention, discrepancies remain regarding whether full attention is required for age-related differences to emerge. The present study took a new approach to this question by varying the contextual demands of emotion processing. This was done by adding perceptual distractions, such as visual and auditory noise, that could disrupt attentional control. Younger and older participants viewed pairs of happy-neutral and fearful-neutral faces while their eye movements were recorded. Facial stimuli were shown either without noise, embedded in a background of visual noise (low, medium, or high), or with simultaneous auditory babble. Older adults showed positive gaze preferences, looking toward happy faces and away from fearful faces; however, their gaze preferences tended to be influenced by the level of visual noise. Specifically, the tendency to look away from fearful faces was not present in conditions with low and medium levels of visual noise but was present when there were high levels of visual noise. It is important to note, however, that in the high-visual-noise condition, external cues were present to facilitate the processing of emotional information. In addition, older adults' positive gaze preferences disappeared or were reduced when they first viewed emotional faces within a distracting context. The current results indicate that positive gaze preferences may be less likely to occur in distracting contexts that disrupt control of visual attention. © 2015 American Psychological Association. Source

Kim J.-N.,Korea Institute of Energy Research | Ko C.H.,Chonnam National University | Yi K.B.,Chungnam National University
International Journal of Hydrogen Energy | Year: 2013

Catalytic absorbents containing CaO and Ca12Al 14O33 and metallic Ni in one body were prepared in combination of precipitation and hydration and tested for sorption enhanced hydrogen production (SEHP). Adding aluminum precursor in the precipitation step induced the formation of Ca12Al14O33 and FIB-TEM analysis revealed that Ca12Al14O33 provides spacious pathway for CO2 diffusion by forming porous structure. In thermogravimetric analysis, Ca12Al14O 33 was identified as an excellent support material providing superior cyclic stability for Ca-based sorbent. Catalytic absorbents were prepared with adding various amount of Ni precursor (3, 5, 7, and 10 wt %). The SEHP test with the catalytic absorbents showed that 7wt% of Ni loading resulted in excellent performance in terms of H2 production and CH4 conversion. Ni agglomeration was observed when 10 wt% of Ni is loaded on the catalytic absorbent. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Shin B.S.,Chungnam National University | Park M.-H.,Dankook University
Korean Journal of Radiology | Year: 2010

Ectopic pregnancy is a potentially life-threatening condition. Detection of ectopic pregnancy on CT images is rare. In this case, we describe the CT findings of interstitial pregnancy both before and after rupture. If CT images demonstrate the presence of a strong enhancing ring-like mass in the pelvis, ectopic pregnancy should be considered. Source

Cho J.,Chungnam National University | Lazarian A.,University of Wisconsin - Madison | Timbie P.T.,University of Wisconsin - Madison
Astrophysical Journal | Year: 2012

One of the main challenges for future 21cm observations is to remove foregrounds which are several orders of magnitude more intense than the H I signal. We propose a new technique for removing foregrounds of the redshifted 21cm observations. We consider multi-frequency interferometer observations. We assume that the 21cm signals in different frequency channels are uncorrelated and the foreground signals change slowly as a function of frequency. When we add the visibilities of all channels, the foreground signals increase roughly by a factor of ∼N because they are highly correlated. However, the 21cm signals increase by a factor of ∼√N because the signals in different channels contribute randomly. This enables us to obtain an accurate shape of the foreground angular power spectrum. Then, we obtain the 21cm power spectrum by subtracting the foreground power spectrum obtained this way. We describe how to obtain the average power spectrum of the 21cm signal. © 2012 The American Astronomical Society. All rights reserved. Source

Cho J.,Chungnam National University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Turbulence is believed to play important roles in the origin of cosmic magnetism. While it is well known that turbulence can efficiently amplify a uniform or spatially homogeneous seed magnetic field, it is not clear whether or not we can draw a similar conclusion for a localized seed magnetic field. The main uncertainty is the rate of magnetic field diffusion on scales larger than the outer scale of turbulence. To measure the diffusion rate of magnetic field on those large scales, we perform a numerical simulation in which the outer scale of turbulence is much smaller than the size of the system. We numerically compare diffusion of a localized seed magnetic field and a localized passive scalar. We find that diffusion of the magnetic field can be much faster than that of the passive scalar and that turbulence can efficiently amplify the localized seed magnetic field. Based on the simulation result, we construct a model for fast diffusion of magnetic field. Our model suggests that a localized seed magnetic field can fill the whole system in ∼Lsys/L times the large-eddy turnover time and that growth of the magnetic field stops in ∼maxâ¡(15,Lsys/L) times the large-eddy turnover time, where Lsys is the size of the system and L is the driving scale. Our finding implies that, regardless of the shape of the seed field, fast magnetization is possible in turbulent systems, such as large-scale structure of the Universe or galaxies. © 2013 American Physical Society. Source

Kim S.Y.,Chungnam National University | Jeon S.H.,Hans Biomedical Daeduk Institute
Journal of Industrial and Engineering Chemistry | Year: 2012

Calcium phosphate cement (CPC) is a promising material for use in minimally invasive surgery for bone defect repair due to its similarity to the mineral phase of bone, biocompatibility, bioactivity, self-setting characteristics, low setting temperature, adequate stiffness and ease of shaping in complicated geometrics. In this study, we systematically investigate the influence of preparation variables on the final properties of CPCs. We determined the effects of CPC composition, accelerators, seed hydroxyapatite and reaction temperatures on the setting times and compressive strength of CPCs based on tetracalcium phosphate (TTCP), dicalcium phosphate dehydrate (DCPD), dicalcium phosphate anhydrous (DCPA), and α-tricalcium phosphate (α-TCP). The three types of CPCs (TTCP/DCPD, TTCP/DCPA, and TTCP/α-TCP-based bone cements) were prepared by varying the amounts of seed hydroxyapatite and citric acid used as a hardening accelerator. After 24. h of incubation, all three types of bone cements exhibited the characteristic peaks attributable to hydroxyapatite (HA) without characteristic peaks of unreacted raw materials. These results indicated that the bone cements were completely converted to HA. TTCP/DCPD-based bone cements showed faster setting times than TTCP/DCPA and TTCP/α-TCP-based bone cements. As citric acid concentrations in the liquid phase increased, the setting times of all three types of bone cements gradually decreased. However, the concentrations of seed HA in the cements were not related to significant changes in setting time. The compressive strengths of CPCs were significantly influenced by composition and reaction temperature. We also studied the effects of immersion time in physiological solution on the properties of the various CPCs. In the results of in vivo tests, subjects with bone defects implanted with CPCs exhibited more bone formation than control subjects that did not receive implantations of CPCs. © 2011 The Korean Society of Industrial and Engineering Chemistry. Source

Quan W.,Sungkyunkwan University | Jo E.-K.,Chungnam National University | Lee M.-S.,Sungkyunkwan University
Diabetes, Obesity and Metabolism | Year: 2013

Apoptosis of pancreatic β-cells is the final step in the development of type 1 diabetes (T1D), leading to critically diminished β-cell mass and contributing to the onset of hyperglycaemia. The spontaneous apoptosis of pancreatic β-cells during pancreas ontogeny also induces cell death-associated inflammation, stimulates antigen-presenting cells and sensitizes naïve diabetogenic T cells. The role of pancreatic β-cell death in type 2 diabetes (T2D) is less clear. In the preclinical period of T2D, hyperinsulinaemia and β-cell hyperplasia develop to compensate for insulin resistance, which is clearly seen in animal models of T2D. For the development of overt T2D, relative insulin deficiency is critical in addition to insulin resistance. Insulin deficiency could be due to β-cell dysfunction and/or decreased β-cell mass. Pancreatic β-cell apoptosis due to lipid injury (lipoapoptosis), endoplasmic reticulum (ER) stress or JNK activation could contribute to the decreased β-cell mass in T2D. Activation of inflammasomes by lipid injury, ER stress, human islet amyloid polypeptide, hyperglycaemia or autophagy insufficiency could also lead to β-cell death or dysfunction. Thus, β-cell death and cell death-associated inflammation through innate immune receptors could be important in both T1D and T2D. © 2013 John Wiley & Sons Ltd. Source

Cho J.,Chungnam National University
Physical Review Letters | Year: 2011

Electron magnetohydrodynamics (EMHD) provides a fluidlike description of small-scale magnetized plasmas. An EMHD wave propagates along magnetic field lines. The direction of propagation can be either parallel or antiparallel to the magnetic field lines. We numerically study propagation of three-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results. (1) Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite-traveling wave packets via self-interaction and cascade energy to smaller scales. (2) EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and two-dimensional (2D) hydrodynamic turbulence. © 2011 American Physical Society. Source

Huang R.H.H.,National Tsing Hua University | Kong A.K.H.,National Tsing Hua University | Takata J.,University of Hong Kong | Hui C.Y.,Chungnam National University | And 2 more authors.
Astrophysical Journal | Year: 2012

We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase-resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission, which is strongest when the pulsar wind interacts with the ablated material from the companion star. The geometry of the peak emission is determined in our study. The marginal softening of the spectrum of the non-thermal X-ray tail may indicate that particles injected at the termination shock are dominated by synchrotron cooling. © 2012. The American Astronomical Society. All rights reserved.. Source

Ma Y.-L.,Nagoya University | Harada M.,Nagoya University | Lee H.K.,Hanyang University | Oh Y.,Kyungpook National University | And 3 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Hadron properties in dense medium are treated in a unified way in a skyrmion model constructed with an effective Lagrangian, in which the ρ and ω vector mesons are introduced as hidden gauge bosons, valid up to O(p4) terms in chiral expansion including the homogeneous Wess-Zumino terms. All the low energy constants of the Lagrangian - apart from the pion decay constant and the vector meson mass - are fixed by the master formula derived from the relation between the five-dimensional holographic QCD and the four-dimensional hidden local symmetry Lagrangian. This Lagrangian allows one to pin down the density n1/2 at which the skyrmions in medium fractionize into half-skyrmions, bringing in a drastic change in the equation of state of dense baryonic matter. We find that the U(1) field that figures in the Chern-Simons term in the five-dimensional holographic QCD action or equivalently the ω field in the homogeneous Wess-Zumino term in the dimensionally reduced hidden local symmetry action plays a crucial role in the half-skyrmion phase. The importance of the ω degree of freedom may be connected to what happens in the instanton structure of elementary baryon noticed in holographic QCD. The most striking and intriguing in what is found in the model is that the pion decay constant that smoothly drops with increasing density in the skyrmion phase stops decreasing at n1/2 and remains nearly constant in the half-skyrmion phase. In accordance with the large Nc consideration, the baryon mass also stays nonscaling in the half-skyrmion phase. This feature which is reminiscent of the parity-doublet baryon model with a chirally invariant mass m0 is supported by the nuclear effective field theory with the parameters of the Lagrangian scaling modified at the skyrmion-half-skyrmion phase transition. It also matches with one-loop renormalization group analysis based on hidden local symmetry. A link between a nonvanishing m0 and the origin of nucleon mass distinctive from dynamically generated mass is suggested. We briefly discuss the possible consequences of the topology change found in this paper on the forthcoming experiments at the rare isotope beam machines under construction. © 2013 American Physical Society. Source

Choi W.-C.,North Carolina A&T State University | Yun H.-D.,Chungnam National University
Materials and Design | Year: 2013

This paper presents experimental results on the long-term deformations of recycled aggregate concrete (RAC) beams for over 1. year (380. days) and flexural behavior of RAC beams after exposure to sustained loading. Three reinforced concrete (RC) beam specimens were fabricated with replacement percentage of aggregate (100% natural aggregate, 100% recycled coarse aggregate, and 50% recycled fine aggregate) and subjected to sustained loading that is 50% of the nominal flexural capacity. During the sustained loading period (380. days), the long-term deflection due to creep and shrinkage was recorded and compared with predicted behavior that was determined based on current specifications (ACI 318 Code). After measuring the long-term deflection for 380. days, four-point bending tests were conducted to investigate the flexural behavior of RC beams after exposure to sustained loading and determine any reduction in flexural capacity. A modified equation to predict the long-term deflection values for RC beams with recycled aggregate is proposed, and the experimental results are compared with the predictions calculated using the ACI 318 Code provisions. © 2013 Elsevier Ltd. Source

Park S.H.,Hanyang University | Lee S.G.,Chungnam National University | Kim S.H.,Hanyang University
Composites Part A: Applied Science and Manufacturing | Year: 2013

Carbon nanotube (CNT)-reinforced polylactide (PLA) nanocomposites were prepared using a melt compounding process employing a twin-screw extruder. The isothermal crystallization kinetics of PLA/CNT nanocomposites according to Avrami's theory were analyzed using differential scanning calorimetry in the temperature range 90-120 °C. There was a significant dependence of CNT on the crystallization behavior of the PLA matrix. The incorporation of CNT improved effectively the crystallization rate of PLA/CNT nanocomposites through heterogeneous nucleation. The nucleating effect of CNTs which increased the number of nucleation sites and decreased the average spherulite size was confirmed using polarized optical microscopy. The rheological properties of the PLA/CNT nanocomposites were also investigated. Changes in the microstructure of the PLA/CNT nanocomposites occurred by incorporating CNT. Furthermore, the tensile strength/modulus and thermal stability of PLA/CNT nanocomposites were enhanced when a very small quantity of CNT was added. This research accounts for the effect of CNTs, which significantly influenced the isothermal behavior, thermal stability, mechanical, and rheological properties of the PLA/CNT nanocomposites, providing a design guide for PLA/CNT nanocomposites in industrial fields. © 2012 Elsevier B.V. All rights reserved. Source

The paper deals with the flexural and cracking behavior experimentally observed in the plain concrete beam with a hybrid polyvinyl alcohol (PVA) and polyethylene (PE) fiber reinforced strain-hardening cement composite (SHCC) layer before and after repeated freeze-thaw exposure. The influences of the SHCC layer thickness, SHCC type, and freezing-thawing cycles on the overall flexural performance of SHCC-layered concrete beams are investigated. Concrete beams, which had 100 × 100 mm rectangular cross section and 300 mm span length, were tested in four-point bending. Two kinds of SHCCs were used as layer materials for the tension zone of concrete beam. Beam specimens with two different SHCC layer thicknesses (30 mm and 50 mm) were prepared. Freezing and thawing tests of SHCC materials and SHCC-layered concrete beams followed ASTM C 666 Procedure B and continued until the specimen achieved 300 freeze-thaw cycles. Experimental study shows that when subject to monotonic flexural loading, the SHCC-layered repair system showed 2.5-3.5 times increased load carrying capacity, and mitigated cracking damage of plain concrete beam with a SHCC layer compared with plain concrete beam. The enhancement in the flexural strength and ductility is found to increase with the SHCC's tensile strain capacity and layer thickness. While the freezing and thawing exposure decreased the deflection at the ultimate flexural strength of SHCC-layered concrete beam, flexural strength of SHCC-layered beam after 300 cycles of freezing and thawing increased up to average 15% compared to that of virgin SHCC-layered concrete beam. © 2012 Elsevier Ltd. All rights reserved. Source

Kang S.,Seoul National University | Min K.,Seoul National University | Yu S.,Chungnam National University
International Journal of Hydrogen Energy | Year: 2012

The proton exchange membrane fuel cell (PEMFC) system with a shell-and-tube gas-to-gas membrane humidifier is considered to be a promising PEMFC system because of its energy-efficient operation. However, because the relative humidity of the dry air flowing into the stack depends on the stack exhaust air, this system can be unstable during transients. To investigate the dynamic behavior of the PEMFC system, a system model composed of a lumped dynamic model of an air blower, a two-dimensional dynamic model of a shell-and-tube gas-to-gas membrane humidifier, and a one-dimensional dynamic model of a PEMFC system is developed. Because the water management during transient of the PEMFC system is one of the key challenges, the system model is simulated at the step change of current. The variations in the PEMFC system characteristics are captured. To confirm the superiority of the system model, it is compared with the PEMFC component model during transients. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights. Source

Lee B.,Agency for Defense Development | Cha H.,Chungnam National University
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2012

In this paper, charging mode of series resonant converter for a high voltage energy storage capacitor are compared in terms of charging time, losses of switch, peak resonant current, voltage and switch utilization in each operation mode. Operating principles of the full bridge series resonant converter with capacitor load are explained and charging characteristics are analyzed in discontinuous and continuous operation mode. Based on the analysis and the simulation focused on above five performance indexes, 0.65ω r < ω s < 0.75ω r is evaluated to the best range of switching frequency for charging of an energy storage capacitor. 1.8 kJ/s SRC prototype is assembled with TI 28335 DSP controller and 40 kJ, 7 kV capacitor. Design rules based on the comparative analysis are verified by experiment. © 2012 IEEE. Source

Choi W.-J.,Chonnam National University | Lee M.-S.,Chonnam National University | Choi J.-E.,Chungnam National University | Yoon S.,Chonnam National University | Kim H.-Y.,Chonnam National University
Global Change Biology | Year: 2013

Here, we experimentally examined how an episodic lack of sunshine (ELS), as an extreme weather event, would affect rice productivity under warming with elevated [CO2]. In 2009 and 2010, rice plants were grown at two levels of [CO2] (ca. 390 and 650 μl l-1) and three levels of warming (≈ambient, +1.2 °C, and +2.2/2.4 °C) in six independent temperature gradient field chambers (three each for ambient and elevated [CO2]). At panicle initiation (PI), booting (BT), or flowering (FL), rice plants were exposed to ELS (ca. 18% of full sunlight) for 10-14 days consecutively. As expected, ELS elicited a significant reduction in aboveground biomass (AGB) and yields. However, elevated [CO2] had the potential to relieve the ELS-induced reduction in AGB and yield, whereas warming had the reverse effect for yields, without a significant warming × [CO2] interaction. When ELS applied at PI, BT, and FL, the extents to which warming-reduced yields (averaged across [CO2] levels) ranged from 9 to 25%, 7 to 14, and 10 to 18% at +1.2 °C, and ranged from 24 to 56%, 22 to 55%, and 18 to 46% at +2.2/2.4 °C across two seasons, respectively. Meanwhile, under normal sunshine they ranged from 1 to 3% at +1.2 °C and 7 to 21% at +2.2/2.4 °C. Warming predisposed rice plants that had experienced ELS to be more sensitive to spikelet sterility and spikelet number per panicle, accounting for most of the yield reductions. These findings provide evidence that an expected warming could further exacerbate rice productivity if ELS occurs simultaneously during reproductive stages. Our results collectively suggest that it might be critically important to consider extreme events for a holistic evaluation of the potential impact of warming and [CO2] on crop productivity, when considering changing climate. © 2012 Blackwell Publishing Ltd. Source

Ahn K.-H.,Chungnam National University
Journal of the Royal Society Interface | Year: 2013

In the ear, hair cells transform mechanical stimuli into neuronal signals with great sensitivity, relying on certain active processes. Individual hair cell bundles ofnon-mammals suchas frogs and turtles are known to showspontaneous oscillation. However, hair bundles in vivo must be quiet in the absence of stimuli, otherwise the signal is drowned in intrinsic noise. Thus, a certain mechanism is required in order to suppress intrinsic noise. Here, through a model study of elastically coupled hair bundles of bullfrog sacculi, we show that a low stimulus threshold and a high signal-to-noise ratio (SNR) can be achieved through the amplitude death phenomenon (the cessation of spontaneous oscillations by coupling). This phenomenon occurs only when the coupled hair bundles have inhomogeneous distribution, which is likely to be the case in biological systems. We show that the SNR has non-monotonic dependence on themass of the overlyingmembrane, and find out that the SNR hasmaximum value in the region of amplitude death. The low threshold of stimulus through amplitude death may account for the experimentally observed high sensitivity of frog sacculi in detecting vibration. The hair bundles' amplitude death mechanism provides a smart engineering design for low-noise amplification. © 2013 The Author(s) Published by the Royal Society. All rights reserved. Source

Kim Y.S.,University of Hawaii at Manoa | Kim K.H.,University of Hawaii at Manoa | Kim C.J.,Chungnam National University
Process Biochemistry | Year: 2012

Myostatin (MSTN) is a potent negative regulator for skeletal muscle growth, and binds to activin type IIB receptor (ActRIIB) for its cellular signal transduction. Administration of the extracellular domain of ActRIIB (ActRIIB-ECD) improved skeletal muscle growth in laboratory animals, suggesting that ActRIIB-ECD can be a useful pharmacological agent to improve skeletal muscle growth of meat-producing animals. In the current study, pig and chicken ActRIIB-ECDs were produced in the Pichia pastoris GS115, and the recombinant proteins were purified from induced culture media by Ni-NTA affinity chromatography. The digestion of pig and chicken ActRIIB-ECDs with PNGase F and glycoprotein staining demonstrated an N-linked glycosylation of these recombinant proteins. Glycoprotein staining also indicated an additional presence of glycosylation in chicken ActRIIB-ECD. Both the pig and chicken ActRIIB-ECDs were shown to inhibit MSTN activity in a reporter gene assay system in vitro. When MSTN-inhibitory potencies were compared by analyzing EC 50 values, no difference in MSTN-inhibitory potency was observed between the glycosylated and N-deglycosylated forms of pig or chicken ActRIIB-ECD, suggesting that glycosylation does not affect the bioactivity of ActRIIB-ECD. MSTN-inhibitory potency of chicken ActRIIB-ECD was greater (P < 0.01) than that of pig ActRIIB-ECD. Results of this study demonstrate that bioactive pig and chicken ActRIIB-ECDs can be produced from P. pastoris. In addition, the study indicates that the N-glycosylation status of ActRIIB-ECD does not affect its bioactivity in vitro. © 2011 Elsevier Ltd. All rights reserved. Source

Shin H.-C.,Korea Institute of Construction Materials | Miyauchi H.,Chungnam National University | Tanaka K.,Tokyo Institute of Technology
Construction and Building Materials | Year: 2011

The effect of temperature on fatigue resistance in repaired mortar and concrete members through epoxy injection is experimentally studied. First, fatigue equipment capable of inducing a small movement is developed to simulate cracks, which are monitored in a real wall structure. The fatigue test is performed considering three different levels of movement amplitude and four different levels of temperature by using fatigue equipment. From the fatigue test, increases in amplitudes and temperature cause reduced resistance to fatigue. Furthermore, the effect of temperature on the failure mode of epoxy-repaired mortar is evaluated. With higher temperature, the failure mode is changed from mortar failure to mixed failure of epoxy and interface. Then, in the mixed failure mode, resistance to fatigue significantly decreases owing to the temperature effect. © 2010 Elsevier Ltd. All rights reserved. Source

Jeong T.J.,National Institute of Biological Resources | Jun J.,National Institute of Biological Resources | Han S.,National Institute of Biological Resources | Kim H.T.,Chungnam National University | And 2 more authors.
Molecular Ecology Resources | Year: 2013

Recently, amphibians and reptiles have drawn attention because of declines in species and populations caused mainly by habitat loss, overexploitation and climate change. This study constructed a DNA barcode database for the Korean herpetofauna, including all the recorded amphibians and 68% of the recorded reptiles, to provide a useful, standardized tool for species identification in monitoring and management. A total of 103 individuals from 18 amphibian and 17 reptile species were used to generate barcode sequences using partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene and to compare it with other suggested barcode loci. Comparing 16S rRNA, cytochrome b (Cytb) and COI for amphibians and 12S rRNA, Cytb and COI for reptiles, our results revealed that COI is better than the other markers in terms of a high level of sequence variation without length variation and moderate amplification success. Although the COI marker had no clear barcoding gap because of the high level of intraspecific variation, all of the analysed individuals from the same species clustered together in a neighbour-joining tree. High intraspecific variation suggests the possibility of cryptic species. Finally, using this database, confiscated snakes were identified as Elaphe schrenckii, designated as endangered in Korea and a food contaminant was identified as the lizard Takydromus amurensis. © 2013 John Wiley & Sons Ltd. Source

Kochuveedu S.T.,Ewha Womans University | Kim D.-P.,Chungnam National University | Kim D.H.,Ewha Womans University
Journal of Physical Chemistry C | Year: 2012

This work is focused on the development of a surface plasmon-induced visible light active photocatalyst system composed of silica-titania core-shell (SiO 2@TiO 2) nanostructures decorated with Au nanoparticles (Au NPs). The influence of size and distribution of Au NPs on photocatalysis, its fabrication methods, and exploration of the mechanism of visible light activity were investigated. A favorable architecture of SiO 2 beads with a thin layer of TiO 2 was decorated with Au NP arrays having different size and areal density. Surface modification of SiO 2@TiO 2 leads to a viable and homogeneous loading of Au NPs on the surface of TiO 2, which renders visible light-induced photocatalytic activity on the whole TiO 2 surface. An optimized system employing Au NP arrays with 15 nm size and 700/μm 2 density showed best catalytic efficiency due to a synergistic effect of the firm contact between Au NPs and TiO 2 and efficiently coupled SPR excitation. A brief mechanism relating the electron transfer from surface-plasmon-stimulated Au NPs to the conduction band of TiO 2 is proposed. © 2011 American Chemical Society. Source

Yu Y.,Chungnam National University
Geochemistry, Geophysics, Geosystems | Year: 2010

Determining the strength of ancient planetary magnetic field is pivotal to understanding the evolution of planets and asteroids in the solar system. While the Thellier-type double heating technique provides the most faithful field strength information for rocks carrying a thermoremanent magnetization (TRM), many extraterrestrial rock samples respond unfavorably to heat treatment. The present study systematically examined the two well-known normalization techniques that avoid any heating by comparing the ratios of TRM/anhysteretic remanent magnetization (ARM) and TRM/saturation isothermal remanent magnetization (SIRM). Both the ratios of TRM/ARM and TRM/SIRM are dependent on the grain size as well as the volume concentration of magnetite. The remanence ratios also were found to increase as the alternating field increased during demagnetization for fine-grained magnetite. A new calibration relation of 2.60 ± 1.32 for the TRM/ARM and of (3.62 ± 1.28) × 10 -2 for the TRM/SIRM was defined for an external field of 50 μT. The TRM/SIRM is superior to TRM/ARM because the former showed less dispersion in the grain size dependence, the volume concentration dependence, and the stability against AF demagnetization. In addition, the standard error of the mean for the TRM/SIRM ratio was smaller than that for the TRM/ARM ratio. Thus, whenever heating is inapplicable, the SIRM method seems to be a better choice than the ARM method. However, it should be emphasized that the uncertainty of TRM/ARM and TRM/SIRM is still nearly an order of magnitude larger than that of the high-fidelity Thellier estimation and thus must be limited in use only when samples are irreversibly altered during heating. In practice, the best approach is to carry out both ARM and SIRM methods and check whether the two estimations agree within the uncertainties. Copyright 2010 by the American Geophysical Union. Source

Kim S.,Chungnam National University
Plastic and Reconstructive Surgery | Year: 2016

BACKGROUND:: One of the most serious complications of breast surgery using implants is capsular contracture. Several preventive treatments have been introduced; however, the mechanism of capsule formation has not been resolved completely. We previously identified negative effects of botulinum toxin type A (BTX-A) on capsule formation, expression of TGF-β1 and differentiation of fibroblasts into myofibroblasts. Thus, we investigated how to prevent capsule formation by BTX-A, particularly via TGF-β1 signaling, in human fibroblasts. METHODS:: In vitro, cultured human fibroblasts were treated with TGF-β1 and/or BTX-A. The expression of collagen, matrix metalloproteinase (MMP), and Smad were examined by Western blotting. The activation of MMP was observed by gelatin zymography. In vivo, the effect of BTX-A on the phosphorylation of Smad2 in silicone-induced capsule formation was evaluated by immunocytochemistry. RESULTS:: In vitro, the phosphorylation of Smad2 was inhibited by BTX-A treatment. The expression levels of collagen types 1 and 3 were inhibited by BTX-A treatment, while those of MMP2 and MMP9 were enhanced. Gelatin zymography experiments confirmed enhanced MMP2 activity in collagen degradation. In vivo, BTX-A treatment reduced capsule thickness and Smad2 phosphorylation in silicone-induced capsules. CONCLUSION:: Our study suggested that BTX-A plays an important role in the inhibition of capsule formation through the TGF-β/Smad signaling pathway. ©2016American Society of Plastic Surgeons Source

Song K.,Tulane University | Han C.,Tulane University | Zhang J.,Tulane University | Lu D.,Tulane University | And 4 more authors.
Hepatology | Year: 2013

MicroRNA-122 (miR-122), a pivotal liver-specific miRNA, has been implicated in several liver diseases including hepatocellular carcinoma (HCC) and hepatitis C and B viral infection. This study aimed to explore epigenetic regulation of miR-122 in human HCC cells and to examine the effect of hepatitis C virus (HCV) and hepatitis B virus (HBV). We performed microRNA microarray analysis and identified miR-122 as the most up-regulated miRNA (6-fold) in human HCC cells treated with 5'aza-2'deoxycytidine (5-Aza-CdR, DNA methylation inhibitor) and 4-phenylbutyric acid (PBA, histone deacetylation inhibitor). Real-time polymerase chain reaction (PCR) analysis verified significant up-regulation of miR-122 by 5'aza and PBA in HCC cells, and to a lesser extent in primary hepatocytes. Peroxisome proliferator activated receptor-gamma (PPARγ) and retinoid X receptor alpha (RXRα) complex was found to be associated with the DR1 and DR2 consensus site in the miR-122 gene promoter which enhanced miR-122 gene transcription. 5-Aza-CdR and PBA treatment increased the association of PPARγ/RXRα, but decreased the association of its corepressors (N-CoR and SMRT), with the miR-122 DR1 and DR2 motifs. The aforementioned DNA-protein complex also contains SUV39H1, an H3K9 histone methyl transferase, which down-regulates miR-122 expression. Conclusions: These findings establish a novel role of the PPARγ binding complex for epigenetic regulation of miR-122 in human HCC cells. Moreover, we show that hepatitis B virus X protein binds PPARγ and inhibits the transcription of miR-122, whereas hepatitis C viral particles exhibited no significant effect; these findings provide mechanistic insight into reduction of miR-122 in patients with HBV but not with HCV infection. © 2013 by the American Association for the Study of Liver Diseases. Source

Kim D.,Korea Institute of Nuclear Safety | Cha H.,Chungnam National University
Conference Proceedings - 2012 IEEE 7th International Power Electronics and Motion Control Conference - ECCE Asia, IPEMC 2012 | Year: 2012

Lead-acid batteries are used for DC power system in nuclear power plants. Standards of periodic surveillance and determining battery capacity for the batteries in the nuclear power plant are summarized. This paper is investigated for environment service condition, specification, advantages and disadvantages of Class 1E battery bank. Class 1E batteries of nuclear power plants in Korea are summarized in terms of specification, such as capacity, discharge rate, bank configuration, discharge end voltage, etc. This paper summarizes standards, and performance test results of the battery in the nuclear power plant. Also this paper analyses performance test results during 12 years and compared performance degradation in the battery bank. © 2012 IEEE. Source

Fabri M.,University of California at Los Angeles | Fabri M.,University of Cologne | Realegeno S.E.,University of California at Los Angeles | Jo E.-K.,Chungnam National University | Modlin R.L.,University of California at Los Angeles
Current Opinion in Immunology | Year: 2011

There is compelling evidence demonstrating a key role for autophagy in host defense against microbial infections. Induction and regulation of autophagy involves complex pathways including signaling molecules that have widespread roles in cell biological functions. For example, inhibiting mTOR by rapamycin, the most widely used chemical approach to induce autophagy, can also result in immunosupression. Nevertheless, advances in our understanding of autophagy provide a new opportunity to modulate host cellular responses as a potential therapeutic strategy to combat microbial infections in humans. © 2010 Elsevier Ltd. Source

Eom I.,Korea Basic Science Institute | Ahn S.-H.,Korea Basic Science Institute | Rhee H.,Korea Basic Science Institute | Rhee H.,Chungnam National University | And 2 more authors.
Physical Review Letters | Year: 2012

We demonstrate that a single-pulse characterization of electronic optical activity-free induction decay, which carries information on both circular dichroism and optical rotatory dispersion, is experimentally feasible. Employing a self-referencing scheme, we show that a highly reliable interferometric chiroptical measurement free from power and phase fluctuations is achievable on a shot-by-shot basis. © 2012 American Physical Society. Source

Kim W.,Korea Ocean Research and Development Institute | Doh S.-J.,Korea University | Yu Y.,Chungnam National University
Atmospheric Environment | Year: 2012

As conveyance media of natural minerals as well as anthropogenic pollutants, the Asian dust storm (ADS) marks a potential impact on human health in the world's most populated region and on the atmospheric energy budget by absorbing/reflecting the solar radiation in a hemispheric-scale. However, the physicochemical state of individual anthropogenic particulates in ADS including the average grain-size and volume concentrations, grain morphology, and the mixing states with natural minerals is not fully understood. Here we trace pollution features of ADS including the temporal atmospheric loadings of particulates carried by ADS using rock magnetic methods and intensive microscopic analyses. Magnetic concentration has coupled with the total suspended particulates in ADS and has increased ~9% for the past four years (2004-2007), resulting mainly from the increasing fossil-fuel combustion in East Asia. Notably, most of the observed particles in ADS contain carbon as a major element and some also contain sulfur. In addition, other anthropogenic elemental signatures encompass iron-oxides of combustion origin and heavy metals (Cr, Pb and Zn). Based on the predominance of carbon contents, increasing the atmospheric temperature in East Asia by ADS loadings can be expected by absorbing solar radiation effectively. © 2011 Elsevier Ltd. Source

Cha S.M.,Chungnam National University
Clinical orthopaedics and related research | Year: 2014

Studies have focused on intramedullary nailing of femoral simple bone cysts but have not clarified the recurrence frequency or management of recurrent cysts. In particular, the affect of pathologic fractures on cyst healing, recurrence, and complications of treatment have not been reported. We performed a retrospective comparative study to examine whether there were differences between simple bone cysts in the proximal femur nailed after pathologic fracture and those without pathologic fracture in terms of (1) healing time, (2) frequency and timing of recurrence, and (3) complications. From 1995 to 2005, 54 patients diagnosed with femoral simple bone cysts were treated and followed for a minimum of 8 years. Flexible nails were inserted in a retrograde fashion in 25 patients with fractures and 29 patients without fractures. The healing period, degree of radiographic consolidation based on the criteria of Capanna et al., recurrence frequency, and final bony abnormalities were analyzed. The mean followups were 107 months (range, 96-124 months) and 103 months (range, 96-140 months) in the groups with and without fractures, respectively. With the numbers available, a post hoc calculation showed that this study had 80% power to detect a difference of 7 months of healing time as significant with a probability less than 0.05. With the numbers available, the mean healing period was not different between groups (25 versus 30 months in the groups with and without fractures, respectively; p = 0.16). Complete healing was observed at 19 versus 18 months, incomplete healing at 5 versus 8 months, and recurrence was observed in one and three patients in the groups with and without fractures, respectively. No differences were found in the distribution of healing grade based on the criteria of Capanna et al. A second surgery was performed using intramedullary nails in two patients with an open physis and compression hip screw fixation was performed in two patients with a closed physis. Finally, the recurrent cysts were classified as completely healed in three patients and incompletely healed in one. Whether a pathologic fracture had occurred before surgical treatment, intramedullary nailing of femoral simple bone cysts resulted in reliable healing, and the frequency of recurrence did not differ. Because this was a retrospective study, the optimal treatment for recurred cysts after intramedullary nailing should be further investigated through a comparative or prospective study. Source

Choi B.-C.,Chungnam National University | Chung J.,Daejeon University
Theoretical Computer Science | Year: 2014

We consider two scheduling problems on a single machine with two agents. The objective is to optimize the performance measure for agent 1 while maintaining the weighted number of just-in-time jobs for agent 2 at or above a given threshold. The performance measures for agent 1 are the total weighted completion times and the weighted number of tardy jobs. We analyze how the complexities of the two problems change, depending on the conditions of processing times and weights. © 2014 Elsevier B.V. Source

Lee Y.,Chungnam National University
Computers and Mathematics with Applications | Year: 2014

We present a numerical method to evaluate financial derivatives under regime-switching jump-diffusion models. The prices of European and American options are derived by solving a partial integro-differential equation (PIDE) and a linear complementarity problem (LCP) respectively. We use the implicit method with three time levels to solve the PIDE and apply it coupled with the operator splitting method to solve the LCP. The proposed method has the advantage not only to avoid any fixed point iteration techniques at each time step, but also to evaluate directly the prices of the European and American options at all states of the economy. It is proved that the implicit method to solve the PIDE for the European option problem is stable with the second-order accuracy in the discrete ℓ2-norm. We perform some numerical simulations to illustrate the analysis of the proposed method under the regime-switching jump-diffusion models. © 2014 Elsevier Ltd. All rights reserved. Source

Kang J.-G.,Chungnam National University | Seog Gwag J.,Yeungnam University | Sohn Y.,Yeungnam University
Ceramics International | Year: 2015

We synthesized Dy(III) complexes with morphologies of nanorods and nanosheets by a hydrothermal method. Cubic phase Dy2O3 nanorods and nanosheets were obtained by high temperature post-thermal annealing of the corresponding complexes. The as-synthesized nanorods consisted of hexagonal phase Dy(OH)3 grown along the [0 0 1] direction. Their physicochemical properties were examined by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction crystallography, UV-visible-NIR absorption, differential scanning calorimetry/thermogravimetric analysis and X-ray photoelectron spectroscopy. © 2014 Elsevier Ltd and Techna Group S.r.l. Source

Ganguly A.,Seoul National University | Ganguly A.,Chungnam National University | Lee S.-H.,Seoul National University | Cho H.-T.,Seoul National University
Plant Journal | Year: 2012

Directional cell-to-cell movement of auxin is mediated by asymmetrically localized PIN-FORMED (PIN) auxin efflux transporters. The polar localization of PINs has been reported to be modulated by phosphorylation. In this study, the function of the phosphorylation sites of the PIN3 central hydrophilic loop (HL) was characterized. The phosphorylation sites were located in two conserved neighboring motifs, RKSNASRRSF(/L) and TPRPSNL, where the former played a more decisive role than the latter. Mutations of these phosphorylatable residues disrupted in planta phosphorylation of PIN3 and its subcellular trafficking, and caused defects in PIN3-mediated biological processes such as auxin efflux activity, auxin maxima formation, root growth, and root gravitropism. Because the defective intracellular trafficking behaviors of phospho-mutated PIN3 varied according to cell type, phosphorylation codes in PIN3-HL are likely to operate in a cell-type-specific manner. © 2012 Blackwell Publishing Ltd. Source

Baik K.H.,Chungnam National University
Journal of the Electrochemical Society | Year: 2013

A perovskite La0.7Sr0.3MnO3 (LSM) coating was deposited by atmospheric plasma spraying in order to improve the oxidation resistance and the area specific resistance (ASR) of ferritic stainless steel (SS430). The plasma-sprayed LSM coating using a smallsized feedstock powder had a low porosity of 1.0 area% and a high electrical conductivity of 148 S/cm at 800°C. The pristine SS430 suffered from a significant oxidation at 800°C in air, and formed a thick thermally grown oxide scale consisting of SiO2, FeCr2O4, Cr2O3 and MnCr2O4. The oxide scale for the SS430 had a relatively low electrical conductivity of ̃3×10-3 S/cm, and therefore the ASR for the oxidized SS430 rapidly increased with oxidation time. The protective LSM coating effectively retarded the growth rate of oxide scale beneath the coating by reducing oxygen inward diffusion. Furthermore, a long-term thermal exposure promoted the formation of duplex Cr2O 3-(Mn,Cr)3O4 scale whose conductivity was estimated to be ̃10-2 S/cm. The growth rate of the duplex Cr2O 3-(Mn,Cr)3O4 scale in the LSM coated SS430 followed a sub-parabolic law which represented a slow growth rate. The corresponding ASR for the LSM coated SS430 was limited to only ̃10 m.cm2 after oxidation at 800°C for 1200 h. © 2013 The Electrochemical Society. Source

Kim Y.,Korea Aerospace Research Institute | Hwang D.-H.,Chungnam National University
Journal of Institute of Control, Robotics and Systems | Year: 2013

The paper investigates the geometric effect of landmarks to the navigation error in the landmark based 3D vision navigation and introduces the INS/Vision integrated navigation system considering its effect. The integrated system uses the vision navigation results taking into account the dilution of precision for landmark geometry. Also, the integrated system helps the vision navigation to consider it. An indirect filter with feedback structure is designed, in which the position and the attitude errors are measurements of the filter. Performance of the integrated system is evaluated through the computer simulations. Simulation results show that the proposed algorithm works well and that better performance can be expected when the error characteristics of vision navigation are considered. © ICROS 2013. Source

Jeong Y.G.,Chungnam National University | Jeon G.W.,Kumoh National Institute of Technology
ACS Applied Materials and Interfaces | Year: 2013

We report microstructure of thermomechanically stable multiwalled carbon nanotube (MWCNT)/poly(m-phenylene isophthalamide) (m-aramid) composite films containing 0.0-10.0 wt % MWCNTs and their performance as electric heating elements. FE-SEM images show that the MWCNTs are well dispersed in the composite films and are wrapped with m-aramid chains and that the interfacial thickness of m-aramid wrapped MWCNTs decreases with the MWCNT content. The electrical resistivity of films varies from ∼1013 Ω cm for the neat m-aramid to ∼100 Ω cm of the film with 10.0 wt % MWCNT owing to the formation of a conductive three-dimensional network of MWCNTs. Accordingly, the performance of MWCNT/m-aramid films as electric heating elements is strongly dependent on MWCNT content as well as applied voltage. For the composite film with 10.0 wt % MWCNT, a maximum temperature of ∼176 C is attained even at a low applied voltage of 10 V. The excellent performance such as rapid temperature response and high electric power efficiency at given applied voltages is found to be related with the microstructural features of the MWCNT/m-aramid films. © 2013 American Chemical Society. Source

Kim Y.-S.,Korea Institute of Science and Technology | Cho E.-S.,Chungnam National University
Advances in Information Sciences and Service Sciences | Year: 2012

Context data is one of most important parts of every context-aware system. Context data is not only trigger of events but also result of these events. So, privacy of context is one of important issue of context-aware system. Established methods of privacy like RBAC are not efficient to context data because these methods cannot control context data itself. So, some methods add abstraction ontology to access control framework. Abstraction ontology control expose of context data. But, using ontology to control expose of context data also have some problems. One is reliability of abstracted value and the other is performance of context data. In this paper, we suggest abstraction based access control system which minimizes abstraction overhead. To do this, we classify context data newly first. Classification of context data is based on abstraction method. And then we propose abstraction method of context data. Few context data use abstraction ontology. But, many of context data do not use abstraction ontology and abstraction of these context data reduces abstraction cost. Source

Cho Y.,Kyungpook National University | Kim Y.H.,Korea Basic Science Institute | Kim Y.H.,Green Nano Materials Research Center | Kim S.,Kyungpook National University | Kim S.,Chungnam National University
Analytical Chemistry | Year: 2011

Planar limits, defined as lines generated by connecting maximum double-bond equivalence (DBE) values at given carbon numbers, are proposed as a means of predicting and understanding the molecular structure of compounds in crude oil. The slopes and y-intercepts of the lines are determined by the DBE/carbon number ratios of functional groups defining the planar limits. For example, the planar limit generated by a serial addition of saturated cyclic rings has a slope of 0.25. The planar limit formed by the linear and nonlinear addition of benzene rings yields lines with slopes of 0.75 and 1, respectively. The y-intercepts of these lines were determined by additional functional groups added within a series of molecules. Plots of DBE versus carbon number for S1 class compounds observed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) showed that saturates/aromatics/resins/asphaltenes (SARA) fractions exhibited unique slopes and y-intercepts. The slope of the planar limit observed from a saturates fraction matched well with the slope of a planar limit generated by the serial addition of saturated cyclic rings. The slopes of planar limits of aromatics and resins fractions were very similar to that obtained from the linear addition of benzene rings. Finally, the slope of the asphaltenes fraction was almost identical to the slope obtained from the nonlinear addition of benzene rings. Simulated and experimental data show that SARA fractions exhibit different molecular structure characteristics. On the basis of the slope and y-intercept of the planar limit, the structures of molecules in SARA fractions were predicted and suggested. The use of planar limits for structural interpretation is not limited to crude oil compounds but can also be used to study other organic mixtures such as humic substances or metabolites. © 2011 American Chemical Society. Source

Akahori T.,Chungnam National University | Yoshikawa K.,University of Tsukuba
Publications of the Astronomical Society of Japan | Year: 2010

We investigate a non-equilibrium ionization state and an electron-ion two-temperature structure of the intra-cluster medium (ICM) in merging galaxy clusters using a series of N-body and hydrodynamic simulations. Mergers wim various sets of mass ratios and impact parameters are systematically investigated, and it is found that, in most cases, ICM significantly departs from the ionization equilibrium state at the shock layers with a Mach number of ̃ 1.5-2.0 in the outskirts of the clusters, and the shock layers with a Mach number of ̃ 2-4 in front of the ICM cores. Accordingly, the intensity ratio between Fexxv and Fexxvi Kα line emissions is significantly altered from that in the ionization equilibrium state. If the effect of the two-temperature structure of ICM is incorporated, the electron temperature is ̃ 10%-20% and ̃30%-50% lower than the mean temperature of ICM at the shock layers in the outskirts and in front of the ICM cores, respectively, and the deviation from the ionization equilibrium state becomes larger. We also address the dependence of the intensity ratio on the viewing angle with respect to the merging plane. © 2010. Astronomical Society of Japan. Source

Kong A.K.H.,National Tsing Hua University | Hui C.Y.,Chungnam National University | Cheng K.S.,University of Hong Kong
Astrophysical Journal Letters | Year: 2010

We report the discovery of gamma-ray emission from the Galactic globular cluster (GC) Terzan 5 using data taken with the Fermi Gamma-ray Space Telescope, from 2008 August 8 to 2010 January 1. Terzan 5 is clearly detected in the 0.5-20 GeV band by Fermi at ∼27σ level. This makes Terzan 5 the second gamma-ray-emitting GC seen by Fermi after 47 Tuc. The energy spectrum of Terzan 5 is best represented by an exponential cutoff power-law model, with a photon index of ∼1.9 and a cutoff energy at ∼3.8 GeV. By comparing Terzan 5 to 47 Tuc, we suggest that the observed gamma-ray emission is associated with millisecond pulsars and is either from the magnetospheres or inverse Compton scattering between the relativistic electrons/positrons in the pulsar winds and the background soft photons from the Galactic plane. Furthermore, it is suggestive that the distance to Terzan 5 is less than 10 kpc and >10 GeV photons can be seen in the future. © 2010. The American Astronomical Society. All rights reserved.. Source

Cho S.,Chungnam National University | Kim G.-S.,Sangji University | Lee J.-H.,Chung - Ang University
Health and Quality of Life Outcomes | Year: 2013

Background: Sleep Hygiene Index (SHI) was designed to assess sleep hygiene. Although the SHI has shown adequate psychometric properties in a nonclinical sample, it has not been validated in a sample with chronic pain. Also, its factor structure, measurement error, and incremental validity over and above other factors affecting sleep quality have not been investigated in a nonclinical sample. Thus, this present study aimed to extend prior psychometric investigation of the SHI. Specifically, we evaluated the factor structure, measurement error, and incremental validity as well as the reliabilities and concurrent validity of the SHI in a sample with chronic pain.Methods: A total of 161 patients seeking treatment in a tertiary pain center located in Seoul, Korea participated. To explore the factor structure of the SHI, we performed an exploratory factor analysis using principal component with varimax. Cronbach's alphas and intraclass correlation coefficients were computed to investigate internal consistency and 2-week test-retest stability of the SHI, respectively. Measurement error was estimated using standard error of measurement and minimum detectable change (MDC) of the SHI. For concurrent validity, Pearson correlations were calculated to examine the relations between the SHI and outcome measures including background variables. Also for incremental validity, a hierarchical multiple regression was performed in relation to sleep quality.Results: Results indicated that two-factor solution is most appropriate; sleep disturbing behavior and environment (B/E) and irregular sleep-wake schedule. Results also showed that the internal consistencies and test-retest stability estimates of the SHI were deemed acceptable. At the 95% confidence level, the MDCs were 5.75 for 'sleep disturbing B/E,' 3.65 for 'irregular sleep-wake schedule,' and 7.49 points for total. The SHI was significantly correlated with age, depression, pain-related anxiety, and sleep quality. Also, sleep quality was significantly predicted by the irregular sleep-wake schedule subscale of the SHI, over and above background variables, pain intensity, depression, pain-related anxiety.Conclusions: The SHI has the reliability, measurement error, and concurrent and incremental validity support for assessing sleep hygiene in a sample with chronic pain. © 2013 Cho et al.; licensee BioMed Central Ltd. Source

Lee J.-H.,Agency for Defense Development | Woo J.-M.,Chungnam National University
IEEE Antennas and Wireless Propagation Letters | Year: 2016

A number of methods are available to obtain the spacing of three-and four-element arrays for a phase interferometer direction-finding (DF) system. Although these methods provide the array spacing having no angle ambiguity, some of these methods do not provide the information about phase error. Furthermore, some methods offer the phase error information but present the limited number of array spacings. The method proposed in this letter provides array spacings that satisfy the maximum phase error that is required at interferometer DF system by using the phase-difference and rotation matrices. © 2015 IEEE. Source

Yang Y.,University of California at Davis | Li J.,University of California at Davis | Li J.,Nanjing University | Wu H.,University of California at Davis | And 3 more authors.
Nano Letters | Year: 2012

We report a simple, controlled doping method for achieving n-type, intrinsic, and p-type lead sulfide (PbS) nanowires (NWs) grown by chemical vapor deposition without introducing any impurities. A wide range of carrier concentrations is realized by adjusting the ratio between the Pb and S precursors. The field effect electron mobility of n-type PbS NWs is up to 660 cm2/(V s) at room temperature, in agreement with a long minority carrier diffusion length measured by scanning photocurrent microscopy (SPCM). Interestingly, we have observed a strong dependence of minority carrier diffusion length on gate voltage, which can be understood by considering a carrier concentration dependent recombination lifetime. The demonstrated ambipolar doping of high quality PbS NWs opens up exciting avenues for their applications in photodetectors and photovoltaics. © 2012 American Chemical Society. Source

Jung S.,Chungnam National University
2012 9th International Conference on Ubiquitous Robots and Ambient Intelligence, URAI 2012 | Year: 2012

This paper presents the novel contact force control approach of a quad-rotor system to interact with the environment in the constrained space. Although the quad-rotor system is not rigid, a contact force in the altitude can be regulated by the position-based impedance force control scheme that adjusts the reference trajectory with respect to the applied force through an admittance filter. This simplifies the force control application. Simulation studies of force tracking control tasks are performed to evaluate the feasibility of the proposed force control schemes. Copyright © 2012 IEEE. Source

Jung J.,Dongguk University | Song K.,Dongguk University | Bae D.R.,Korea Basic Science Institute | Lee S.W.,Chungnam National University | And 2 more authors.
Nanoscale | Year: 2013

β-FeOOH nanorod (NR) catalysts prepared by ultrasonic-irradiated chemical synthesis enabled lithium-air cells to have high round-trip efficiency and extremely low overpotential as well as an outstanding rate capability. Good catalytic activities of the β-FeOOH NR bundle could be ascribed to its crystal structure, which consists of 2 × 2 tunnels formed by edge- and corner-sharing Fe(O,OH)6 octahedra as well as to its one-dimensional morphology, which makes the configured electrode highly porous, indicating that the -OOH-based catalyst can be a good substitute for oxide-base catalysts in lithium-air batteries. The ultrasonic-irradiated chemical synthesis suggested here may be a good solution to optimize the morphology of catalyst materials for maximum catalytic activity. © 2013 The Royal Society of Chemistry. Source

Park S.,Chungnam National University
Korean Journal of Anesthesiology | Year: 2016

The null hypothesis significance test method is popular in biological and medical research. Many researchers have used this method for their research without exact knowledge, though it has both merits and shortcomings. Readers will know its shortcomings, as well as several complementary or alternative methods, as such the estimated effect size and the confidence interval. © the Korean Society of Anesthesiologists, 2016. Source

Kwon H.-J.,U.S. National Institutes of Health | Kwon H.-J.,Chungnam National University | Won Y.-S.,U.S. National Institutes of Health | Won Y.-S.,Korea Research Institute of Bioscience and Biotechnology | And 3 more authors.
Hepatology | Year: 2014

Prednisolone is a corticosteroid that has been used to treat inflammatory liver diseases such as autoimmune hepatitis and alcoholic hepatitis. However, the results have been controversial, and how prednisolone affects liver disease progression remains unknown. In the current study we examined the effect of prednisolone treatment on several models of liver injury, including T/NKT cell hepatitis induced by concanavalin A (ConA) and α-galactosylceramide (α-GalCer), and hepatotoxin-mediated hepatitis induced by carbon tetrachloride (CCl4) and/or ethanol. Prednisolone administration attenuated ConA- and α-GalCer-induced hepatitis and systemic inflammatory responses. Treating mice with prednisolone also suppressed inflammatory responses in a model of hepatotoxin (CCl4)-induced hepatitis, but surprisingly exacerbated liver injury and delayed liver repair. In addition, administration of prednisolone also enhanced acetaminophen-, ethanol-, or ethanol plus CCl4-induced liver injury. Immunohistochemical and flow cytometric analyses demonstrated that prednisolone treatment inhibited hepatic macrophage and neutrophil infiltration in CCl4-induced hepatitis and suppressed their phagocytic activities in vivo and in vitro. Macrophage and/or neutrophil depletion aggravated CCl4-induced liver injury and impeded liver regeneration. Finally, conditional disruption of glucocorticoid receptor in macrophages and neutrophils abolished prednisolone-mediated exacerbation of hepatotoxin-induced liver injury. Conclusion: Prednisolone treatment prevents T/NKT cell hepatitis but exacerbates hepatotoxin-induced liver injury by inhibiting macrophage- and neutrophil-mediated phagocytic and hepatic regenerative functions. These findings may not only increase our understanding of the steroid treatment mechanism but also help us to better manage steroid therapy in liver diseases. © 2014 by the American Association for the Study of Liver Diseases. Source

Song J.,Dankook University | Lee E.,Chungnam National University | Cho B.-K.,Dankook University
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2013

A well-defined (PEO-PS)2-PLA miktoarm terpolymer (1) was synthesized by stepwise click reactions of individually prepared poly(ethylene oxide) (PEO), polystyrene (PS, polymerized by atom transfer radical polymerization), and polylactide (PLA, polymerized by ring-opening polymerization) blocks. As characterized by differential scanning calorimetry and small-angle X-ray scattering techniques, the terpolymer self-assembled into a hexagonal columnar structure consisting of PLA/PEO cylindrical cores surrounded by PS chains. In contrast, the ion-doped sample (1-Li+) with lithium concentration per ethylene oxide = 0.2 exhibited a three-phase lamellar structure, which was attributed to the microphase separation between PEO and PLA blocks and to the conformational stabilization of the longest PLA chain. The two-phase columnar morphology before the ion doping was used to prepare a nanoporous material. PLA chains in the cylindrical core region were hydrolyzed by sodium hydroxide, producing nanopores with a pore diameter of about 14 nm. The resulted nanoporous material sank to the bottom in water, because of water-compatible PEO chains on the walls. © 2012 Wiley Periodicals, Inc. Source

Han O.H.,Korea Basic Science Institute | Han O.H.,Chungnam National University | Han O.H.,Kyungpook National University
Progress in Nuclear Magnetic Resonance Spectroscopy | Year: 2013

The article focuses on NMR investigations of electrochemical reactions and dynamic properties closely related to electrochemical reactions in low temperature FCs operating in acidic conditions such as polymer electrolyte membrane FCs and direct alcohol FCs, mainly reported over the last 10 years. The first in situ NMR investigation of FCs was carried out with a homemade toroid cavity detector NMR probe dedicated for in situ NMR analyses of the electrochemical reactions on the different anode catalysts, such as carbon supported PtRu, and Pt in real direct methanol FCs. Compounds in the anode exhausts of direct ethanol FCs have been detected under operating conditions by using high performance liquid chromatography and gas chromatography, however, sequential trapping of the electrochemical reaction products was necessary to convert the products to chemicals detectable by high performance liquid chromatography and a cold trap to collect anode products was used for the gas chromatography analyses. Source

Choi T.H.,Chungnam National University | Liang R.,James Franck Institute | Maupin C.M.,Colorado School of Mines | Voth G.A.,James Franck Institute
Journal of Physical Chemistry B | Year: 2013

The self-consistent charge density functional tight binding (SCC-DFTB) method has been applied to hydroxide water clusters and a hydroxide ion in bulk water. To determine the impact of various implementations of SCC-DFTB on the energetics and dynamics of a hydroxide ion in gas phase and condensed phase, the DFTB2, DFTB2-γh, DFTB2-γh+gaus, DFTB3-diag, DFTB3-diag+gaus, DFTB3-Full+gaus, and DFTB3-3OB implementations have been tested. Energetic stabilities for small hydroxide clusters, OH -(H2O)n, where n = 4-7, are inconsistent with the results calculated with the B3LYP and second order Møller-Plesset (MP2) levels of ab initio theory. The condensed phase simulations, OH -(H2O)127, using the DFTB2, DFTB2-γh, DFTB2-γh+gaus, DFTB3-diag, DFTB3-diag+gaus, DFTB3-Full+gaus and DFTB3-3OB methods are compared to Car-Parrinello molecular dynamics (CPMD) simulations using the BLYP functional. The SCC-DFTB method including a modified O-H repulsive potential and the third order correction (DFTB3-diag/Full+gaus) is shown to poorly reproduce the CPMD computational results, while the DFTB2 and DFTB2-γh method somewhat more closely describe the structural and dynamical nature of the hydroxide ion in condensed phase. The DFTB3-3OB outperforms the MIO parameter set but is no more accurate than DFTB2. It is also shown that the overcoordinated water molecules lead to an incorrect bulk water density and result in unphysical water void formation. The results presented in this paper point to serious drawbacks for various DFTB extensions and corrections for a hydroxide ion in aqueous environments. © 2013 American Chemical Society. Source

Kim S.-W.,Ewha Womans University | Lee K.,Chungnam National University | Nam K.,Yeshiva University
Energy Policy | Year: 2010

Using STAR models, we investigate the nonlinear dynamic properties and the interdependence of CO2 emissions and economic growth for Korea. The estimation results indicate that the growth rate of both CO2 emissions and industrial production exhibit a significant nonlinear asymmetric dynamics. While the linear Granger causality test finds no causality in any direction, the results of the nonlinear Granger causality tests show a two-way causality between CO2 emissions and economic growth. The strong mutual causation between CO2 emissions and economic activities indicates that the economic impact from CO2 mitigation is expected to be higher in Korea. This suggests that the appropriate energy and environmental policy be to mitigate CO2 emissions while having less impact on the economy. © 2010 Elsevier Ltd. All rights reserved. Source

Chang C.,Chungnam National University | Zoback M.D.,Stanford University
Journal of Petroleum Science and Engineering | Year: 2010

Laboratory creep experiments show that compaction of dry Gulf of Mexico shale is a permanent irrecoverable process associated with viscoplastic deformation. In order to find a relatively simple model that can describe such viscoplastic behavior of the dry frame of the shale, we combined the Perzyna viscoplasticity constitutive law with a modified Cambridge clay plastic yield model. The constitutive equation for this model is a power-law function that relates strain rate to the ratio of dynamic and static yield surfaces defined by the modified Cam-clay model. By incorporating the effect of strain hardening on the static yield pressure, we derived an equation relating volumetric creep strain at a constant hydrostatic pressure level to the logarithm of time, which is in good agreement with experimental results. We determined the model parameters by fitting experimental data of creep strain as a function of time. The determined parameters indicate that the yield stress of the hydrostatically loaded shale increases by 6-7% as strain rate rises by an order of magnitude. This demonstrates that the laboratory-based prediction of yield stress (as well as porosity) may be significantly overestimated. Thus, strain-rate calibration is required for weak shales such as those studied here to appropriately estimate physical properties under in situ conditions. © 2010 Elsevier B.V. Source

Kandpal L.M.,Chungnam National University
Sensors (Basel, Switzerland) | Year: 2013

Spectroscopy has proven to be an efficient tool for measuring the properties of meat. In this article, hyperspectral imaging (HSI) techniques are used to determine the moisture content in cooked chicken breast over the VIS/NIR (400-1,000 nm) spectral range. Moisture measurements were performed using an oven drying method. A partial least squares regression (PLSR) model was developed to extract a relationship between the HSI spectra and the moisture content. In the full wavelength range, the PLSR model possessed a maximum  of 0.90 and an SEP of 0.74%. For the NIR range, the PLSR model yielded an  of 0.94 and an SEP of 0.71%. The majority of the absorption peaks occurred around 760 and 970 nm, representing the water content in the samples. Finally, PLSR images were constructed to visualize the dehydration and water distribution within different sample regions. The high correlation coefficient and low prediction error from the PLSR analysis validates that HSI is an effective tool for visualizing the chemical properties of meat. Source

Yoon S.H.,Chungnam National University
Korean Journal of Anesthesiology | Year: 2012

Septic patients portray instable hemodynamic states because of hypotension or cardiomyopathy, caused by vasodilation, thus, impairing global tissue perfusion and oxygenation threatening functions of critical organs. Therefore, it has become the primary concern of anesthesiologists in conducting anesthesia (induction, maintenance, recovery, and postoperative care), especially in the induction of those who are prone to fall into hemodynamic crisis, due to hemodynamic instability. The anesthesiologist must have a precise anesthetic plan based on a thorough preanesthetic evaluation because many cases are emergent. Primary circulatory status of patients, including mental status, blood pressure, urine output, and skin perfusion, are necessary, as well as more active assessment methods on intravascular volume status and cardiovascular function. Because it is difficult to accurately evaluate the intravascular volume, only by central venous pressure (CVP) measurements, the additional use of transthoracic echocardiography is recommended for the evaluation of myocardial performance and hemodynamic state. In order to hemodynamically stabilize septic patients, adequate fluid resuscitation must be given before induction. Most anesthetic induction agents cause blood pressure decline, however, it may be useful to use drugs, such as ketamine or etomidate, which carry less cardiovascular instability effects than propofol, thiopental and midazolam. However, if blood pressure is unstable, despite these efforts, vasopressors and inotropic agents must be administered to maintain adequate perfusion of organs and cellular oxygen uptake. © the Korean Society of Anesthesiologists, 2012. Source

Kang S.,Seoul National University | Min K.,Seoul National University | Yu S.,Chungnam National University
International Journal of Hydrogen Energy | Year: 2010

Water management is a crucial factor in determining the performance of proton exchange membrane fuel cell (PEMFC) for automotive application. The shell-and-tube water-to-gas membrane humidifier is useful for humidifying the PEMFC due to its good performance. Shell-and-tube water-to-gas membrane humidifiers have liquid water on one side of the tube wall and a dry gas on the other. In order to investigate humidifier performance, a two-dimensional dynamic model of a shell-and-tube water-to-gas membrane humidifier is developed. The model is discretized into three control volumes - shell, tube and membrane - in the cross-sectional direction to resolve the temperature and species concentration of the humidifier. For validation, the dew point temperature of the simulation result is compared with that of experimental data and shows good agreement with only a slight difference. The distribution of humidification characteristics can be captured using the discretization along the air-flow direction. The humidification performance of two different flow configurations, counter and parallel, are compared under various operating conditions and geometric parameters. Finally, the dynamic response of the humidifier at the step-change of various air flow rates is investigated. These results suggest that the model can be used to optimize the inlet flow humidity of a PEMFC. Crown Copyright © 2009. Source

Kim S.,Chungnam National University | Oh H.,Cranfield University | Oh H.,Defence Academy of the United Kingdom | Tsourdos A.,Cranfield University | Tsourdos A.,Defence Academy of the United Kingdom
Journal of Guidance, Control, and Dynamics | Year: 2013

This paper proposes a nonlinear model-predictive control framework for coordinated standoff tracking by a pair of unmanned aerial vehicles. The benefit of this approach is to get optimal performance compared with using a decoupled controller structure: heading control for standoff-distance keeping and speed control for phase keeping. The overall controller structure is fully decentralized as each unmanned aerial vehicle optimizes its controller based solely on the future propagation of the pair vehicle states and the target estimates received via communication. This paper uses an acceleration model for sophisticated and realistic target dynamics, which can consider a more reasonable system noise covariance matrix reflecting the target's motion characteristics. To simplify optimization formulation and decrease computation burden, a new manipulation using the inner product of position vectors of the unmanned aerial vehicles with respect to the target position is proposed for antipodal tracking instead of using the relative phase-angle difference. To consider a more realistic situation, inequality constraints are considered for collision avoidance between unmanned aerial vehicles and control input saturations using penalty functions in the model-predictive control scheme. Simulations with a pair of unmanned aerial vehicles are done using realistic car trajectory data in an urban environment in the United Kingdom to verify the feasibility and benefit of the proposed approach with comparing to a Lyapunov vector field guidance. Copyright © 2011 by Seungkeun Kim, Hyondong Oh, and Antonios Tsourdos. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Source

Choi J.-I.,Chonnam National University | Kim H.-J.,Chungnam National University
Carbohydrate Polymers | Year: 2013

Fucoidan is a marine sulfated polysaccharide with a wide variety of biological activities. Recently, it has been reported that low molecular weight fucoidan has the enhanced antioxidant and anticoagulative activities. However, degradation techniques such as enzymolysis and acid hydrolysis for obtaining low molecular weight fucoidan, have the disadvantages such as narrow substrate specificity and unfavorable hydrolysis of side groups, respectively. In this study, low molecular weight fucoidan was prepared by gamma-irradiation. When fucoidan was gamma-irradiated, the molecular weight rapidly dropped to 38 kDa when the sample was irradiated at 10 kGy, then gradually dropped to 7 kDa without the significant elimination of the sulfate groups. Low molecular weight fucoidan had higher cytotoxicity than native fucoidan in cancer cells, such as AGS, MCF-7, and HepG-2. In addition, low molecular weight fucoidan showed higher inhibitory activity of cell transformation, which resulted in higher anticarcinogenicity. This result suggests that low molecular weight fucoidan with enhanced biological activities can be produced by a simple irradiation method without changing the functional groups. © 2013 Elsevier Ltd. All rights reserved. Source

Patra A.K.,Korea Institute of Geoscience and Mineral Resources | Kim D.-J.,Korea Institute of Geoscience and Mineral Resources | Chung H.-S.,Konyang University | Lee S.-W.,Chungnam National University
Hydrometallurgy | Year: 2013

Two step leaching experiments were carried out to extract nickel, vanadium, and molybdenum present in spent refinery catalyst. A bioleaching process was applied in the first step. Pulp density, initial Fe(II) concentration, initial pH, particle size, and temperature were varied to optimize the bioleaching process. Ni, V, and Mo were leached out with maximum recoveries of 97%, 92% and 53%, respectively, at an optimized bioleaching condition of initial ferrous ion of 2 g/L, initial pH of 2, pulp density of 10% (w/v), particle size of (-106+45) μm, and a temperature of 35 °C. As the Mo leaching rate was very low, a second leaching step for the bioleached residue was applied with different concentrations of (NH4)2CO3, Na 2CO3, or H2SO4. The second step leaching was optimum at a concentration of 30 g/L (NH4) 2CO3 with respect to Mo extraction. The rate of Mo dissolution with respect to concentration of lixiviant in the second leaching step was evaluated. The percentages of Ni, V, and Mo leached were 97%, 97% and 99%, respectively, by combining the first step under optimized conditions and the second step with 30 g/L (NH4)2CO3. © 2012 Elsevier B.V. All rights reserved. Source

Bartolome L.,KAIST | Imran M.,King Saud University | Lee K.G.,University of Michigan | Sangalang A.,KAIST | And 2 more authors.
Green Chemistry | Year: 2014

There have been numerous studies to develop catalysts for the chemical recycling of poly(ethylene terephthalate) (PET) via glycolysis. However, in the field of PET glycolysis, only a few have attempted to recover and reuse the catalysts. This research utilized easily recoverable superparamagnetic γ-Fe2O3 nanoparticles as a reusable catalyst for PET glycolysis. γ-Fe2O3 nanoparticles were produced by calcining Fe3O4 nanoparticles prepared by the co-precipitation method. The produced γ-Fe2O3 nanoparticles had an average size of 10.5 ± 1.4 nm, and a very high surface area reaching 147 m2 g-1. Its superparamagnetic property was also confirmed. Glycolysis reactions were carried out, and the γ-Fe2O3 catalysts were recovered after the reactions by simple magnetic decantation. The use of magnetic iron oxide allowed the easy recovery of the catalyst from the glycolysis products. At 300 °C and a 0.05 catalyst/PET weight ratio, the maximum bis(2-hydroxyethlyl) terephthalate (BHET) monomer yield reached more than 90% in 60 min. At 255 °C and a 0.10 catalyst/PET weight ratio, the BHET yield reached more than 80% in 80 min. The catalyst was reused 10 times, giving almost the same BHET yield each time. © 2014 The Royal Society of Chemistry. Source

Hoa N.D.,Hanoi University of Science and Technology | Quang V.V.,Hanoi University of Science and Technology | Kim D.,Chungnam National University | Hieu N.V.,Hanoi University of Science and Technology
Journal of Alloys and Compounds | Year: 2013

The development of a general, low-cost, and scalable method for synthesizing nanowire (NW) structures made of different materials for use in the fast and accurate detection of toxic and flammable gases is extremely important for monitoring environmental pollution and gas leakage. This study reports on a scalable and general route for synthesizing nanowire-structured semiconducting metal oxides for gas nanosensors. Different metal oxide nanowires made of titanium oxide, tin oxide, zinc oxide, copper oxide, and tungsten oxide, were synthesized via sputter deposition of correlative metals over porous single-walled carbon nanotubes (SWNTs) templates followed by oxidation. The microstructures and morphologies of the metal oxide nanowires were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that the synthesized materials could be nanowires or bead-like nanowires, depending on the adhesion between the deposited metals and the SWNTs substrates. Different metal oxide nanowires with lengths of up to several micrometers and controllable diameters could be easily synthesized and were found to be suitable for gas sensor applications. This synthetic method is expected to introduce new strategies and promised potential applications for NWs in other fields, such as in photocatalysts, electrochemicals, and biosensors. © 2012 Elsevier B.V. All rights reserved. Source

Jeong Y.G.,Chungnam National University | An J.-E.,Kumoh National Institute of Technology
Composites Part A: Applied Science and Manufacturing | Year: 2014

Epoxy-based composite films are fabricated by film-casting and thermal-curing of epoxy resin/hardener mixtures with 5.0 wt% mixed carbon fillers of different compositions of graphene and MWCNT. The electrical resistivity of the composite films decreases from ∼103 to ∼102 Ω cm with increasing the MWCNT composition in the mixed carbon fillers, which results from the bridge effect of MWCNTs among graphene sheets. Accordingly, maximum temperature of the composite films attained at an applied voltage increases with the MWCNT composition in the hybrid carbon fillers. The composite films exhibit excellent electric heating performance in terms of temperature response rapidity and electric power efficiency. © 2013 Elsevier Ltd. All rights reserved. Source

Ba Linh N.T.,Soonchunhyang University | Lee K.-H.,Chungnam National University | Lee B.-T.,Soonchunhyang University
Journal of Biomedical Materials Research - Part A | Year: 2013

New biodegradable mats was successfully obtained by functional polyvinyl alcohol (PVA)/Gelatin (GE) blend fiber mats containing different BCP amounts (20, 40, and 50 w/v%) of biphasic calcium phosphate (BCP) nanoparticles for bone regeneration. BCP nanoparticles were loaded and dispersed successfully in the PVA/GE fibrous matrix. The addition of BCP was found to have increased fiber diameter, tensile strength, osteoblast cell adhesion, proliferation, and protein expression. Compared to the others, the 50% BCP-loaded electrospun PVA/GE fibers had the most favorable mechanical properties, cell attachment and growth, and protein expression. In vivo bone formation was examined using rat models, and increased bone formation was observed for the 50% BCP-loaded electrospun PVA/GE blends within 2 and 4 weeks. This result suggests that the 50% BCP-PVA/GE composite nanofiber mat has high potential for use in the field of bone regeneration and tissue engineering. Copyright © 2013 Wiley Periodicals, Inc. Source

Cho T.-Y.,Woojin Precision Co. | Han C.-W.,Korea Institute of Energy Research | Yoon S.-G.,Chungnam National University
Journal of Alloys and Compounds | Year: 2013

We fabricated the dye-sensitized solar cells (DSCs) with new type of working electrode, which consisted of conductive and flexible stainless steel mesh sheet coated with 170 nm-thick TiO2 blocking layer deposited using various deposition techniques. Stainless mesh samples with blocking layer showed higher efficiency than those without a blocking layer. The best cell property in the present study showed the open circuit voltage of 0.58 V, short-circuit current density of 11.98 mA/cm2, fill factor of 0.45, and efficiency of 3.11%. © 2013 Elsevier B.V. All rights reserved. Source

Park J.H.,Hundai WIA | Jung S.,Chungnam National University
Mechatronics | Year: 2013

This article presents a Mechatronics approach to make the complex dynamical system satisfy the specification as desired. The Mechatronics approach has several phases: analytical design, system integration, sensing & control, and evaluation. The Mechatronics approach means that cycles of design, implementation, sensing, and control are repeated until the system satisfies the goal through evaluation. A single-wheel robot system called GYROBO after a robot that uses gyroscopic effect is developed and controlled by the Mechatronics approach. The goal of GYROBO is to navigate its terrain while maintaining the stable balance. However, successful balancing and navigation of a single-wheel robot are quite difficult and challenging since one point contact may fall down in lateral direction with ease. To have a successful balancing performance, many problems have to be solved a priori before applying any advanced control algorithms. Among several phases of analytical design, integration, sensing & control, and evaluation, the most important phase is the analytical design. However, the analytical design cannot guarantee successful performances due to the complexity of the system. Practical Mechatronic approach is to repeat cycles of system integration, sensing & control, and evaluation. After several modifications of mechanical assembly and relocation of components inside the wheel housing, simple linear controllers enable GYROBO to perform successful balancing and navigation. GYROBO is able to follow the specified trajectory given by a remote operator. Experimental studies of control of balancing, driving forward and backward, turning, and climbing over an obstacle of GYROBO are conducted to demonstrate and evaluate its functionality and support the concept of the Mechatronics approach to control complex systems. © 2013 Elsevier Ltd. All rights reserved. Source

Jeong S.,LG Corp | Jung S.,Chungnam National University
Journal of Institute of Control, Robotics and Systems | Year: 2013

In this paper, a simple design of a DOB (Disturbance Observer) for attitude control of a quad-rotor system is presented. A modified DOB structure from the conventional DOB is introduced to eliminate time-delay in the calculation. The proposed simple modification in the DOB configuration provides an efficiency in the calculation of the disturbance term such that the delayed calculation is not required. The performance of the modified DOB is evaluated through simulation studies. To confirm the simulation results, experimental studies of the attitude control of a quad-rotor system are conducted. © ICROS 2013. Source

Hong S.G.,IT Convergence Technology Research Laboratory | Kim N.S.,IT Convergence Technology Research Laboratory | Kim W.W.,Chungnam National University
ETRI Journal | Year: 2013

A passive infrared or pyroelectric infrared (PIR) sensor is mainly used to sense the existence of moving objects in an indoor environment. However, in an outdoor environment, there are often outbreaks of false alarms from environmental changes and other sources. Therefore, it is difficult to provide reliable detection outdoors. In this paper, two algorithms are proposed to reduce false alarms and provide trustworthy quality to surveillance systems. We gather PIR signals outdoors, analyze the collected data, and extract the target features defined as window energy and alarm duration. Using these features, we model target and false alarms, from which we propose two target decision algorithms: window energy detection and alarm duration detection. Simulation results using real PIR signals show the performance of the proposed algorithms. © 2013 ETRI. Source

Kang H.,Pusan National University | Ryu D.,Chungnam National University | Jones T.W.,University of Minnesota
Astrophysical Journal | Year: 2012

Recent radio observations have identified a class of structures, so-called radio relics, in clusters of galaxies. The radio emission from these sources is interpreted as synchrotron radiation from GeV electrons gyrating in μG-level magnetic fields. Radio relics, located mostly in the outskirts of clusters, seem to associate with shock waves, especially those developed during mergers. In fact, they seem to be good structures to identify and probe such shocks in intracluster media (ICMs), provided we understand the electron acceleration and re-acceleration at those shocks. In this paper, we describe time-dependent simulations for diffusive shock acceleration at weak shocks that are expected to be found in ICMs. Freshly injected as well as pre-existing populations of cosmic-ray (CR) electrons are considered, and energy losses via synchrotron and inverse Compton are included. We then compare the synchrotron flux and spectral distributions estimated from the simulations with those in two well-observed radio relics in CIZA J2242.8+5301 and ZwCl0008.8+5215. Considering that CR electron injection is expected to be rather inefficient at weak shocks with Mach number M ≲ a few, the existence of radio relics could indicate the pre-existing population of low-energy CR electrons in ICMs. The implication of our results on the merger shock scenario of radio relics is discussed. © © 2012. The American Astronomical Society. All rights reserved. Source

Sharma P.,Korea Institute of Energy Research | Yeo J.-G.,Korea Institute of Energy Research | Kim D.K.,Korea Institute of Energy Research | Cho C.H.,Chungnam National University
Journal of Materials Chemistry | Year: 2012

Nanosize NaA zeolite particles of sizes ranging from 70 to 150 nm were hydrothermally synthesized from a high concentration inorganic precursor solution without using any organic additive. The nanocrystalline NaA zeolite particles have mesopores of pore diameter 2-20 nm. The mesoporous character was incurred by the intercrystalline and interparticular voids. © 2012 The Royal Society of Chemistry. Source

Kim B.S.,Seoul National University | Jeong Y.G.,Chungnam National University | Shin K.,Seoul National University
Journal of Physical Chemistry B | Year: 2013

The crystallization behavior and the orientation of linear alkane hentetracontane (C41) confined in cylindrical nanoporous alumina templates with different surface energies were investigated by nonisothermal crystallization and X-ray diffraction. The surface of pristine nanoporous alumina was modified to have low surface energy by grafting with polydimethylsiloxane. In the pristine nanoporous alumina, C41 crystallized at two crystallization temperature ranges, lower than bulk, and exhibited the decreased Avrami exponents. C41 in the surface-modified nanoporous alumina showed the inhibition of crystallization at higher temperature range among the two crystallization temperature ranges but the enhancement of crystallization at much lower temperature ranges than in the pristine nanoporous alumina. It was clearly shown that those variations of crystallization behavior imply the surface effect on crystallization. The crystal orientation was also affected by surface-modification of the alumina template. The a-axis of orthorhombic C41 crystals in the pristine nanoporous alumina was preferentially oriented parallel to the pore axis, while b-and c-axes were perpendicular to the pore axis. C41 crystals in the surface-modified nanoporous alumina showed two types of orientation. One was identical to that in the pristine nanoporous alumina, and the other was the orientation that the crystals were tilted with respect to the c-axis as the (110) plane parallel to the pore axis. © 2013 American Chemical Society. Source

Kim K.,Chungnam National University
Mathematical Problems in Engineering | Year: 2013

This paper discusses a computational method to construct positive realizations with sparse matrices for continuous-time positive linear systems with multiple complex poles. To construct a positive realization of a continuous-time system, we use a Markov sequence similar to the impulse response sequence that is used in the discrete-time case. The existence of the proposed positive realization can be analyzed with the concept of a polyhedral convex cone. We provide a constructive algorithm to compute positive realizations with sparse matrices of some positive systems under certain conditions. A sufficient condition for the existence of a positive realization, under which the proposed constructive algorithm works well, is analyzed. © 2013 Kyungsup Kim. Source

Choi T.H.,Chungnam National University
Bulletin of the Korean Chemical Society | Year: 2014

This report introduces Gaussian electrostatic models (GEMs) to account for charge penetration effects in water-water interactions, allowing electrostatic interactions to be accurately described. Three different Gaussian electrostatic models, GEM-3S, GEM-5S, and GEM-6S are designed with s-type Gaussian functions. The coefficients and exponents of the Gaussian functions are optimized using the electrostatic potential (ESP) fitting procedure based on that of the MP2/aug-cc-pVTZ method. The electrostatic energies of ten different water dimers that were calculated with GEM-6S agree well with the results of symmetry-adapted perturbation theory (SAPT), indicating that this designed model can be effectively applied to future water models. Source

Cho I.,Yeungnam University | Kang J.-G.,Chungnam National University | Sohn Y.,Yeungnam University
Bulletin of the Korean Chemical Society | Year: 2014

We uniformly coated Eu(III)- and Tb(III)-doped yttrium oxide onto the surface of SiO2 spheres and then characterized them by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction crystallography and UV-Visible absorption. 2D and 3D photoluminescence image map profiles were reported for the core-shell type structure. Red emission peaks of Eu(III) were observed between 580 to 730 nm and assigned to 2D0→ 7FJ (J =0- 4) transitions. The green emission peaks of Tb(III) between 450 and650 nm were attributed to the 5D4→ 7FJ (J = 6, 5, 4, 3) transitions. For annealed samples, Eu(III) ions were embedded at a C2 symmetry site in Y2O3, which was accompanied by an increase in luminescence intensity and redness, while Tb(III) was changed to Tb(IV), which resulted in no green emission. Source

Burkinshaw S.M.,University of Leeds | Son Y.-A.,Chungnam National University
Dyes and Pigments | Year: 2010

5% omf dyeings of three 1:2 pre-metallised acid dyes displayed poor fastness to repeated washing at 60 °C on 0.05 dtex 'supermicrofibre' artificial nylon suede. Although fastness was improved by an aftertreatment with the full backtan, considerable dye loss still occurred during repeated washing, which was attributed to the large surface area of the microfibre substrate. In contrast, the wash fastness of 4% omf dyeings of three vat dyes, applied as both the alkali leuco and acid leuco variants, was substantially better than that of the acid dyes, despite the considerably higher colour strength of the vat dyeings. Although the rub fastness of the vat dyeings was higher than that of the acid dyeings, the level of rub fastness, especially wet, was only moderate. The colour and colour strength of the acid leuco dyeings were generally different to those of the alkali leuco dyeings. © 2010 Elsevier Ltd. All rights reserved. Source

Kim J.S.,Samsung | Jung S.,Chungnam National University
Applied Soft Computing Journal | Year: 2015

This article presents the hardware implementation of the floating-point processor (FPP) to develop the radial basis function (RBF) neural network for the general purpose of pattern recognition and nonlinear control. The floating-point processor is designed on a field programmable gate array (FPGA) chip to execute nonlinear functions required in the parallel calculation of the back-propagation algorithm. Internal weights of the RBF network are updated by the online learning back-propagation algorithm. The on-line learning process of the RBF chip is compared numerically with the results of the RBF neural network learning process written in the MATLAB program. The performance of the designed RBF neural chip is tested for the real-time pattern classification of the XOR logic. Performances are evaluated by comparing results from the MATLAB through extensive experimental studies. © 2014 Elsevier B.V. Source

Ku J.H.,Seoul National University | Ryu J.H.,Seoul National University | Kim S.H.,Korea Basic Science Institute | Han O.H.,Korea Basic Science Institute | And 2 more authors.
Advanced Functional Materials | Year: 2012

This work demonstrates that structural defects in amorphous metal oxide electrodes can serve as a reversible Li + storage site for lithium secondary batteries. For instance, molybdenum dioxide electrode in amorphous form (a-MoO 2) exhibits an unexpectedly high Li + storage capacity (up to four Li per MoO 2 unit), which is larger by a factor of four than that for the crystalline counterpart. The conversion-type lithiation is discarded for this electrode from the absence of Mo metal and lithium oxide (Li 2O) in the lithiated a-MoO 2 electrode and the retention of local structural framework. The sloping voltage profile in a wide potential range suggests that Li + ions are inserted into the structural defects that are electrochemically nonequivalent. This electrode also shows an excellent cycle stability and rate capability. The latter feature is seemingly due to a rather opened Li + diffusion pathway provided by the structural defects. A high Li + mobility is confirmed from nuclear magnetic resonance study. An amorphous MoO 2 (a-Mo 2)electrode exhibits an unexpectedly high Li + storage capacity (up to 810 mA h g -1), which is larger by a factor of four than that of its crystalline counterpart. Li + ions are hosted by the structural defects in a-MoO 2 and opened vacancies and void spaces give a much faster charge/discharge rate as compared with the crystalline counterpart. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kim D.-H.,Korea University of Technology and Education | Lee G.-W.,Chungnam National University | Kim Y.-C.,Korea University of Technology and Education
Solid State Communications | Year: 2012

Interaction of a zinc interstitial (Zn i) with an oxygen vacancy (V O) was investigated to understand an origin of natively n-type characteristics of ZnO using density functional theory with the hybrid functional. The V O-Zn i complex is formed with a formation of 3.82 eV and is a shallow donor with 1 charge state near the conduction band minimum. Its formation energy, however, is not low enough to be stable thermodynamically. Energy barrier for Zn i migration in the V O-Zn i complex is studied to consider its existence from kinetic aspect, and a high value of 1.3 eV is obtained with the kick-out process. Therefore, the bound Zn i to V O can exist and supply electrons for native n-type ZnO kinetically. © 2012 Elsevier Ltd. All rights reserved. Source

Lee Y.-H.,Dankook University | Kim B.,Chungnam National University | Kim H.-J.,Gyeongnam National University of Science and Technology
Computers and Mathematics with Applications | Year: 2012

Localizing an object within an image is a common task in the field of computer vision, and represents the first step towards the solution of the recognition problem. This paper presents an efficient approach to object localization for image retrieval using query-by-region. The new algorithm utilizes correlogram back-projection in the YCbCr chromaticity components to handle the problem of subregion querying. Utilizing similar spatial color information enables users to detect and locate primary location and candidate regions accurately without the need for further information about the number of objects. Comparing this new approach to existing methods, an improvement of 21% was observed in experimental trials. These results reveal that color correlograms are markedly more effective than color histograms for this task. © 2011 Elsevier Ltd. All rights reserved. Source

Jang G.,Seoul National University | Kim M.K.,Chungnam National University | Lee B.C.,Seoul National University
Theriogenology | Year: 2010

Although somatic cell nuclear transfer (SCNT) technology and applications are well developed in most domesticated and laboratory animals, their use in dogs has advanced only slowly. Many technical difficulties had to be overcome before preliminary experiments could be conducted. First, due to the very low efficiency of dog oocyte maturation in vitro, in vivo matured oocytes were generally used. The nucleus of an in vivo matured oocyte was removed and a donor cell (from fetal or adult fibroblasts) was injected into the oocyte. Secondly, fusion of the reconstructed oocytes was problematic, and it was found that a higher electrical voltage was necessary, in comparison to other mammalian species. By transferring the resulting fused oocytes into surrogate females, several cloned offspring were born. SCNT was also used for producing cloned wolves, validating reproductive technologies for aiding conservation of endangered or extinct breeds. Although examples of transgenesis in canine species are very sparse, SCNT studies are increasing, and together with the new field of gene targeting technology, they have been applied in many fields of veterinary or bio-medical science. This review summarizes the current status of SCNT in dogs and evaluates its potential future applications. © 2010 Elsevier Inc. Source

Jang Y.-C.,Chungnam National University | Kim M.,Jeju National University
Resources, Conservation and Recycling | Year: 2010

Environmentally sound management of end-of-life mobile phones is an issue of growing concern in Korea and around the world. This paper discusses the generation rate, collection systems, and recycling processes of used & end-of-life mobile phones in Korea. The results were based on review of the existing literature, a survey of 1090 consumers, site visits to electronic waste recycling facilities, and interviews with mobile telecommunication companies and environmental regulatory authorities. The results show that on average 14.5 million mobile phones have been retired annually in Korea over the period of analysis (2000-2007). A large fraction of used & end-of-life mobile phones has been stored at home waiting for disposal. Approximately five million used & end-of-life mobile phones have been collected by mobile telecommunication companies and producers annually between 2004 and 2007. The results of the consumer survey showed that the average Korean consumer typically replaces his/her mobile phone every 28.8 months. Since collection and recycling of mobile phones has only recently started, the methods and infrastructure for collection and recycling process for used & end-of-life mobile phones have not yet been well-established. More active collection activities and systems for used & end-of-life mobile phone are still needed, adding more collection points where consumers can drop off their used mobile phones. Producers, consumers, mobile telecommunication companies, and local governments should consider more collective actions that can be taken to promote successful collection and recycling schemes. © 2010 Elsevier B.V. All rights reserved. Source

Hwangbo K.-H.,Kongju National University | Kim M.R.,Kongju National University | Lee C.-S.,Chungnam National University | Cho K.Y.,Kongju National University
Soft Matter | Year: 2011

We demonstrate the new fabrication of uniform polymer microparticles exhibiting not only an internal porous structure but also a golf-ball-like dimple pattern on the surface. The method provides a simple route for engineering the physical aspects of microparticles and can also be applied to various polymers that have been a continuous challenge in microparticle engineering. The final appearance of the porous structure interior of the microparticles was determined by the selection of amorphous or semi-crystalline polymers. © 2011 The Royal Society of Chemistry. Source

Kim M.-W.,Samsung | Rim S.,Chungnam National University | Yi C.-H.,Sogang University | Kim C.-M.,Sogang University
Optics Express | Year: 2013

We investigate the impact of local dynamics on chaos-Assisted tunneling in a highly deformed microcavity whose classical ray dynamics exhibits a small measure of trapezoidal-shaped orbit (TSO) stability islands in a main chaotic sea. These two classically completely decomposed regions in phase space can support resonance modes of their own respectively. Using numerical ray and wave analyses, we show that the emission characteristics of the TSO resonance mode are determined by local ray dynamics near TSO islands. The emission characteristics of the other high-Q resonance modes, on the other hand, are governed by usual ray-wave correspondence. We experimentally demonstrate that the TSO emission mode can be lased without selective excitations by devising a half-moon shaped highly deformed cavity. And we also show that the emission characteristics of the TSO lasing modes are well explained by numerical ray and wave analyses.©2013 Optical Society of America. © 2013 Optical Society of America. Source

Singh A.P.,State University of New York at Buffalo | Shin Y.G.,Chungnam National University | Shah D.K.,State University of New York at Buffalo
Pharmaceutical Research | Year: 2015

Characterization and prediction of the pharmacokinetics (PK) and pharmacodynamics (PD) of Antibody-Drug Conjugates (ADCs) is challenging, since it requires simultaneous quantitative understanding about the PK-PD properties of three different molecular species i.e., the monoclonal antibody, the drug, and the conjugate. Mathematical modeling and simulation provides an excellent tool to overcome these challenges, as it can simultaneously integrate the PK-PD of ADCs and their components in a quantitative manner. Additionally, the computational PK-PD models can also serve as a cornerstone for the model-based drug development and preclinical-to-clinical translation of ADCs. To provide an overview of this subject matter, this manuscript reviews the PK-PD models applicable to ADCs. Additionally, the usage of these models during different drug development stages (i.e., discovery, preclinical development, and clinical development) is also emphasized. The importance of PK-PD modeling and simulation in making rationale go/no-go decisions throughout the drug development process is also highlighted. There is an array of PK-PD models available, ranging from the systems models specifically developed for ADCs to the empirical models applicable to all chemotherapeutic agents, which one can employ for ADCs. The decision about which model to choose depends on the questions to be answered, time at hand, and resources available. © 2015 Springer Science+Business Media New York Source

Park C.H.,Chungnam National University
Journal of Computer Science | Year: 2015

Several hashing-based methods for Approximate Nearest Neighbors (ANN) search in a large data set have been proposed recently. In particular, semi-supervised hashing utilizes semantic similarity given for a small fraction of pairwise data samples and active hashing aims to improve the performance for ANN search by relying on an expert for the labeling of the most informative points. In this study, we present an active hashing method by prototype-based sample selection. Knowing semantic similarities between cluster prototypes can help extracting relations among the points in the corresponding clusters. For expert labeling, we select prototypes from clusters which do not contain any data points with labeled information so that all areas can be covered effectively. Experimental results demonstrate that the proposed active hashing method improves the performance for ANN search. © 2015 Cheong Hee Park. Source

Kim Y.J.,Chungnam National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2011

We retrospectively analyzed comparative toxicities and efficacies of chemotherapy regimens in advanced gastric cancer (AGC) patients who achieved complete response (CR) after chemotherapy. We reviewed the medical records of 1,203 patients, who were pathologically diagnosed as AGC in a single center between January 2001 and October 2007. On the basis of the Response Evaluation Criteria in Solid Tumors, CR was evaluated with abdominal computed tomography. Toxicities were evaluated using the National Cancer Institute's common toxicity criteria before each chemotherapy cycle. Among the 1,203 AGC patients enrolled in this study, 568 received chemotherapy and 635 received best supportive care. The major chemotherapy regimens were 5-fluorouracil, leucovorin and oxaliplatin (FOLFOX), docetaxel, cisplatin and 5-fluorouracil (DCF) and 5-fluorouracil, leucovorin and irinotecan (FOLFIRI). Among the 568 patients, 51 (9.0%) achieved CR (49 [8.6%] with FOLFOX [n=12], DCF [n=26], or FOLFIRI [n=11] and 2 [0.3%] with etoposide, leucovorin and 5-fluorouracil). For patients administered FOLFOX, DCF, and FOLFIRI, the median time to disease progression was 4 months (range, 1.8-59.5), 15 months (range, 2.9-31.2) and 10 months (range, 2.0-39.5), and the median survival times were 48 months (range, 5.9-74.0), 37 months (range, 14.0-86.0), and 30 months (range, 6.0-50.0), respectively. Grades 3-4 mucositis occurred mostly in patients administered DCF (n=8, 30.8%). Grades 3-4 leucopenia were observed in 1 (8.3%), 11 (42.3%), and 4 (36.4%) patients administered FOLFOX, DCF and FOLFIRI, respectively. No statistically significant differences were observed in the 3 regimens. All 3 regimens (FOLFOX, DCF and FOLFIRI) were active and tolerable. Their efficacies and toxicities were not significantly different. Source

Song J.,University of California at Santa Barbara | Han O.H.,Korea Basic Science Institute | Han O.H.,Chungnam National University | Han S.,University of California at Santa Barbara
Angewandte Chemie - International Edition | Year: 2015

Nafion, the most widely used polymer for electrolyte membranes (PEMs) in fuel cells, consists of a fluorocarbon backbone and acidic groups that, upon hydration, swell to form percolated channels through which water and ions diffuse. Although the effects of the channel structures and the acidic groups on water/ion transport have been studied before, the surface chemistry or the spatially heterogeneous diffusivity across water channels has never been shown to directly influence water/ion transport. By the use of molecular spin probes that are selectively partitioned into heterogeneous regions of the PEM and Overhauser dynamic nuclear polarization relaxometry, this study reveals that both water and proton diffusivity are significantly faster near the fluorocarbon and the acidic groups lining the water channels than within the water channels. The concept that surface chemistry at the (sub)nanometer scale dictates water and proton diffusivity invokes a new design principle for PEMs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Giorgi M.,University of Pisa | Yun H.,Chungnam National University
Veterinary Journal | Year: 2012

Mirtazapine (MRT) is a human antidepressant drug mainly metabolised by the cytochrome P450 enzyme system to 8-OH mirtazapine (8-OH) and dimetilmirtazapine (DMR). The drug is usually administered to dogs with anorexia according to doses extrapolated from humans, although it could also have applications as an antidepressant and analgesic in this species. The aim of this study was to assess the pharmacokinetics of MRT and its metabolites, DMT and 8-OH. Six healthy male Beagle dogs were administered MRT orally (20. mg/dog) and plasma MRT and metabolite concentrations were evaluated by high performance liquid chromatography with fluorescence detection.The pharmacokinetic profiles of MRT and DMR were similar (detected from 0.25 up to 10. h), while 8-OH (detected from 0.50 up to 10. h) attained the highest concentrations. The mean half-life of MRT was 6.17. h with a clearance of 1193. mL/h/kg. The study showed that MRT has a different pharmacokinetic profile in the dog compared to other species. © 2011 Elsevier Ltd. Source

Lim H.H.,Chungnam National University
Journal of Pediatric Endocrinology and Metabolism | Year: 2015

We investigated whether there is a relationship between serum cholesterol and bone mineral density (BMD), independent of BMI in children and adolescents. This study was based on data from the KNHANES 2009-2010. The data for 1557 children and adolescents were analyzed and classified into three groups: underweight, normal-weight, and overweight. We analyzed the relationships between serum cholesterol and BMD z-scores. Whole body BMD z-score was revealed as an inverse association with the serum cholesterol quartile in only normal-weight group (p=0.008). Serum cholesterol level correlated more inversely with BMD z-score in normal-weight boys (r2=0.040, p=0.002) than in girls (r2=0.019, p=0.042). Multivariate regression analysis identified serum cholesterol as association with BMD in normal-weight (r2=0.020, p=0.002). Serum cholesterol concentration may be a detrimental risk factor for BMD in normal-weight children and adolescents independent of BMI. © 2015 by De Gruyter. Source

Kang J.-G.,Chungnam National University | Min B.-K.,Yeungnam University | Sohn Y.,Yeungnam University
Journal of Alloys and Compounds | Year: 2014

We synthesized hexagonal phase Pr(OH)3nanorods by a hydrothermal method and obtained cubic phase Pr6O11by post-thermal annealing at above 550 °C. Pr(OH)3nanorod growth was found to occur in the [0 0 1] direction. Upon thermal annealing, the oxidation state of Pr(III) was changed to Pr(III, IV). The physicochemical properties were fully examined by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) crystallography, UV-Visible-NIR absorption, differential scanning calorimetry/thermogravimetric analysis (DSC/TGA), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR) and CO oxidation activity tests. © 2014 Elsevier B.V. All rights reserved. Source

Xiao Z.,Dalian University of Technology | Wang A.,Dalian University of Technology | Kim D.-P.,Chungnam National University
Journal of Materials Chemistry | Year: 2010

Three-dimensional (3D) macroporous SiCN ceramic patterns with tailored window size and pore shape were fabricated by thermal deformation of a close-packed polystyrene (PS) sphere template, which was obtained by applying consecutive capillary force and centrifugation in a packing process of a few hours. Subsequent infiltration of a viscous preceramic inorganic polymer under strong centrifugal force was followed by pyrolysis at 800 °C to decompose the sacrificial PS sphere-packed template. In this work, the window sizes among the interconnected macropores were controlled in the range of 258 to 740 nm by tailoring the shape of the packed PS spheres (diameter 1.5 μm) by annealing above the glass transition temperature (Tg) of the PS spheres for different periods. The pore shapes changed from circular to hexagonal, and the BET surface area of the samples was reduced from 443 to 337 m2 g -1 with a thinner network skeleton. This approach should be useful in combining a low pressure drop with high external surface area for microfluidic applications with 3D porous structures. © 2010 The Royal Society of Chemistry. Source

The aim of the present study was to investigate effects of the ethyl acetate fraction of an ethanol extract of Coix lachryma-jobi (ECLJ) on glucose uptake and adipocyte differentiation in 3T3-L1 cells. ECLJ phosphorylated AMP-activated protein kinase (AMPK) and its downstream substrate acetyl-coenzymeA carboxylase in 3T3-L1 cells in a time- and dose-dependent manner. Moreover, we discovered that compound C inhibits ECLJ-stimulated ACC phosphorylation. In addition, ECLJ exhibited a dose-dependent stimulation of glucose uptake in 3T3-L1 cells, and this increase was obviously attenuated by compound C. ECLJ also caused a decrease in the expression levels of adipogenesis factors such as fatty acid synthase, sterol-regulatory-element-binding protein-1c, peroxisome proliferator-activated receptor γ, and CAATT/enhancer binding protein α in a dose-dependent manner. Differentiation was examined by Oil red O staining activity after ECLJ treatment for 6 days. ECLJ decreased mean droplet size. These results suggest a possible role for AMPK in the process of adipose differentiation and that ECLJ targeted for adipocyte functions could be effective in improving the symptoms of metabolic syndrome. Source

Hui C.-Y.,Chungnam National University
Journal of Astronomy and Space Science | Year: 2013

Here we review the effort of Fermi Asian Network (FAN) in exploring the supernova remnants (SNRs) with state-of-art high energy observatories, including Fermi Gamma-ray Space Telescope and Chandra X-ray Observatory, in the period of 2011-2012. Utilizing the data from Fermi LAT, we have discovered the GeV emission at the position of the Galactic SNR Kes 17 which provides evidence for the hadronic acceleration. Our study also sheds light on the propagation of cosmic rays from their acceleration site to the intersteller medium. We have also launched an identification campaign of SNR candidates in the Milky Way, in which a new SNR G308.3-1.4 have been uncovered with our Chandra observation. Apart from the remnant, we have also discovered an associated compact object at its center. The multiwavelength properties of this X-ray source suggest it can possibly be the compact binary that survived a supernova explosion. © The Korean Space Science Society. Source

Jiang Z.,CAS Institute of Geology and Geophysics | Jiang Z.,University of Chinese Academy of Sciences | Liu Q.,CAS Institute of Geology and Geophysics | Barron V.,University of Cordoba, Spain | And 2 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2012

Hematite, a ubiquitous mineral in aerobic sediments and soils of temperate and warm areas, is weakly magnetic. However, it carries a stable natural remanent magnetization, and thus can reflect paleoenvironment changes. To quantify the influence of Al content in hematite on its magnetic properties, two series of hematite particles were prepared by hydrothermal transformation of ferrihydrite in aqueous suspension (HFh* series) and by thermal dehydration of goethite (HG* series). Crystal morphological and mineral magnetic properties of these two types of hematites differ distinctively. More specifically, the HFh* series samples display oblate (plate-like) morphologies, while the HG* series samples are prolate (highly acicular). HFh* series samples display higher saturation magnetization but lower magnetic coercivity than that of the HG* series. It is tenable that a better lattice ordering of Al substitution occurs during the process of dehydration of goethite than after transformation from ferrihydrite, resulting in weaker saturation magnetization for HG* series samples. The origin of single domain (SD) hematite in nature can be diagnosed by the correlation of unblocking temperature and magnetic coercivity: a positive correlation indicates the presence of pure (Al-free) SD hematite, while a negative correlation indicates a chemical origin of SD Al-substituted hematite. These results bear new information on decoding the complex magnetic properties of SD Al-hematite in nature environments, and thus deepen our understanding of the mechanism of variations in both paleomagnetic and paleoenvironmental signals carried by Al-hematite. Copyright © 2012 by the American Geophysical Union. Source

Santos-Lima R.,University of Sao Paulo | Santos-Lima R.,University of Wisconsin - Madison | Lazarian A.,University of Wisconsin - Madison | De Gouveia Dal Pino E.M.,University of Sao Paulo | And 2 more authors.
Astrophysical Journal | Year: 2010

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding fast magnetic reconnection in the presence of turbulence reassures that the magnetic field behavior in computer simulations and turbulent astrophysical environments is similar, as far as magnetic reconnection is concerned. This makes it meaningful to perform MHD simulations of turbulent flows in order to understand the diffusion of magnetic field in astrophysical environments. Our studies of magnetic field diffusion in turbulent medium reveal interesting new phenomena. First of all, our three-dimensional MHD simulations initiated with anti-correlating magnetic field and gaseous density exhibit at later times a de-correlation of the magnetic field and density, which corresponds well to the observations of the interstellar media. While earlier studies stressed the role of either ambipolar diffusion or time-dependent turbulent fluctuations for de-correlating magnetic field and density, we get the effect of permanent de-correlation with one fluid code, i.e., without invoking ambipolar diffusion. In addition, in the presence of gravity and turbulence, our three-dimensional simulations show the decrease of the magnetic flux-to-mass ratio as the gaseous density at the center of the gravitational potential increases. We observe this effect both in the situations when we start with equilibrium distributions of gas and magnetic field and when we follow the evolution of collapsing dynamically unstable configurations. Thus, the process of turbulent magnetic field removal should be applicable both to quasi-static subcritical molecular clouds and cores and violently collapsing supercritical entities. The increase of the gravitational potential as well as the magnetization of the gas increases the segregation of the mass and magnetic flux in the saturated final state of the simulations, supporting the notion that the reconnection-enabled diffusivity relaxes the magnetic field + gas system in the gravitational field to its minimal energy state. This effect is expected to play an important role in star formation, from its initial stages of concentrating interstellar gas to the final stages of the accretion to the forming protostar. In addition, we benchmark our codes by studying the heat transfer in magnetized compressible fluids and confirm the high rates of turbulent advection of heat obtained in an earlier study. © 2010 The American Astronomical Society. All rights reserved. Source

Sung Y.J.,Chungnam National University
Palpu Chongi Gisul/Journal of Korea Technical Association of the Pulp and Paper Industry | Year: 2010

The properties of paper are very susceptible to moisture content originated from relative humidity. This propensity of PVA impregnated paper was investigated in this study. Especially the hardening effect of borax treatment after PVA impregnation on the response of paper sample to the relative humidity was evaluated. When the moisture content was increased with the relative humidity, tensile stretch and tear resistance were increased while tensile strength and stiffness were decreased. A great increase in folding endurance of PVA impregnated paper sample was found at the higher relative humidity. The borax treatment could reduce the response of PVA impregated paper to the relative humidity. Source

Ryu D.,Chungnam National University | Das S.,Indian Institute of Technology Guwahati | Kang H.,Pusan National University
Astrophysical Journal | Year: 2010

We studied howthe intergalactic magnetic field (IGMF) affects the propagation of super-Greisen-Zatsepin-Kuzmin (GZK) protons that originate from extragalactic sources within the local GZK sphere. To this end, we set up hypothetical sources of ultra-high-energy cosmic rays (UHECRs), virtual observers, and the magnetized cosmic web in a model universe constructed from cosmological structure formation simulations.We then arranged a set of reference objectsmimicking active galactic nuclei (AGNs) in the local universe,with which correlations of simulated UHECR events are analyzed.With our model IGMF, the deflection angle between the arrival direction of super-GZK protons and the sky position of their actual sources is quite large with a mean value of ? ∼ 15°? and a median value of ? ∼ 7°-10°. On the other hand, the separation angle between the arrival direction and the sky position of nearest reference objects is substantially smaller with S ∼ 3°? 5-4°, which is similar to the mean angular distance in the sky to nearest neighbors among the reference objects. This is a direct consequence of our model that the sources, observers, reference objects, and the IGMF all trace the matter distribution of the universe. The result implies that extragalactic objects lying closest to the arrival direction of UHECRs are not necessarily their actual sources. With our model for the distribution of reference objects, the fraction of super-GZK proton events, whose closest AGNs are true sources, is less than 1/3.We discussed implications of our findings for correlation studies of realUHECRevents. © 2010. The American Astronomical Society. Source

Hui C.Y.,Chungnam National University | Hui C.Y.,University of Hong Kong | Cheng K.S.,University of Hong Kong | Taam R.E.,Northwestern University