• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.6
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• pp.1034-1043
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• 2015

This is the continuation of a numerical study on vortex shedding from a blunt trailing-edge of a hydrofoil. In our previous work (Lee et al., 2015), numerical schemes for efficient computations were successfully implemented; i.e. multiple domains, the approximation of domain boundary conditions using cubic spline functions, and particle-based domain decomposition for better load balancing. In this study, numerical results through a hybrid particle-mesh method which adopts the Vortex-In-Cell (VIC) method and the Brinkman penalization model are further rigorously validated through comparison to experimental data at the Reynolds number of $2{\times}10^6$. The effects of changes in numerical parameters are also explored herein. We find that the present numerical method enables us to reasonably simulate vortex shedding phenomenon, as well as turbulent wakes of a hydrofoil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2158-2164
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• 2015

In u-GIS environments, various load shedding techniques have been researched in order to balance loads caused by input spatial data streams. However, typical load shedding methods on aspatial data lack regard for characteristics of spatial data, also previous load shedding approaches on spatial, which still lack regard for spatial data density or dynamic input data stream, give rise to troubles on spatial query processing performance and accuracy. Therefore, dynamic load shedding scheme over spatial data stream is proposed through stored spatial data deviation and load ratio of input data stream in order to improve spatial continuous query accuracy and performance in u-GIS environment. In proposed scheme, input data which are a big probability related to spatial continuous query may be a strong chance to be dropped relatively.

• 한국가시화정보학회:학술대회논문집
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• 2001.12a
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• pp.86-99
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• 2001

Vortex lock-on or resonance in the flow behind a circular cylinder is investigated from a time-resolved PIV when a single frequency oscillation is superimposed on the mean incident velocity. Measurements are made of the $K\acute{a}rm\acute{a}n$ and streamwise vortices in the wake-transition regime at the Reynolds number 360. Streamwise vortices at the lock-on and natural shedding states are observed, as well as the changes in the wake region with the change of the shedding frequency of lock-on state. When lock-on occurs, the vortex shedding frequency is found to be half the oscillation frequency as expected from previous experiments. At the lock-on state, the $K\acute{a}rm\acute{a}n$ vortices are observed to be more disordered by the increased strength and spanwise wavelength of the streamwise vortices, which leads to a strong three-dimensional motion. Recirculation and vortex formation region at the lock-on state is reduced as the oscillating frequency is increased. By comparing the Reynolds stresses at the lock-on and natural shedding states, $\bar{u'u'}\;and \;\bar{u'u'}$ at the lock-on state are concentrated on the shear layer around the cylinder. The $\bar{u'u'}\;at\;f_o/f_n=2.0$ has a large value near the centerline, compared with that of other cases. Considering the traces of maximum of u', in the wake region near the cylinder, wake width at the lock-on state is wider than that at the natural shedding state.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.3
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• pp.211-217
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• 2014

This study analyzes the nonlinear interaction between two different vortex shedding frequencies from a cylinder with two diameters. In particular, two different vortex shedding frequencies are generated by preparing a cylinder having two diameters artificially. Flow velocity fluctuations behind the cylinder are measured three-dimensionally. Additionally, we fabricated a hole and placed a pressure transducer for measuring the pressure on the cylinder surface. The pressure signal from the pressure transducer is used as basic signal. A TSC(Trans Spectrum Coherence) is used for checking the strength of the nonlinear interaction between two different vortex shedding frequencies. As a result, the following are clarified: i) frequency distribution behind the cylinder, ii) three-dimensional flow state behind the cylinder through calculation of ensemble average, and iii) close relationship between the vertical vortex and change of low frequency by nonlinear interaction between two different vortex shedding frequencies from the cylinder with two diameters.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.435-439
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• 2008

We evaluated the patterns of serology and fecal viral shedding for any differences by hemagglutination inhibition (HI) and real-time PCR on Korean CPV-2 isolates (CPV-2a-I, CPV-2a-V and CPV-2b). We successfully detected fecal viral shedding from samples extracted 2-3 d.p.i., regardless of the onset of clinical signs. In addition, the pattern of viral shedding differed depending on the CPV-2 isolates used for inoculation. We also observed differences in the serological pattern that was also depended on the CPV-2 isolates inoculated. The onset and amount of fecal viral shedding were not correlated with the level of antibody titers in this study. Our study is a valuable resource for understanding the different pathobiology of the CPV-2 isolates and the correlation between the patterns of serum antibody titer and fecal viral shedding.

• Molecules and Cells
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• v.45 no.8
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• pp.564-574
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• 2022

Epithin/PRSS14 is a membrane serine protease that plays a key role in tumor progression. The protease exists on the cell surface until its ectodomain shedding, which releases most of the extracellular domain. Previously, we showed that the remaining portion on the membrane undergoes intramembrane proteolysis, which results in the liberation of the intracellular domain and the intracellular domain-mediated gene expression. In this study, we investigated how the intramembrane proteolysis for the nuclear function is initiated. We observed that ectodomain shedding of epithin/PRSS14 in mouse breast cancer 4T1 cells increased depending on environmental conditions and was positively correlated with invasiveness of the cells and their proinvasive cytokine production. We identified selenite as an environmental factor that can induce ectodomain shedding of the protease and increase C-C motif chemokine ligand 2 (CCL2) secretion in an epithin/PRSS14-dependent manner. Additionally, by demonstrating that the expression of the intracellular domain of epithin/PRSS14 is sufficient to induce CCL2 secretion, we established that epithin/PRSS14-dependent shedding and its subsequent intramembrane proteolysis are responsible for the metastatic conversion of 4T1 cells under these conditions. Consequently, we propose that epithin/PRSS14 can act as an environment-sensing receptor that promotes cancer metastasis by liberating the intracellular domain bearing transcriptional activity under conditions promoting ectodomain shedding.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.51-53
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• 2006

• Journal of Life Science
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• v.23 no.5
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• pp.650-656
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• 2013

Endothelial protein C receptor (EPCR) plays a pivotal role in augmenting Protein C activation through the thrombin-thrombomodulin complex. EPCR activity is markedly changed by ectodomain cleavage and released as the soluble protein (sEPCR). EPCR shedding is mediated by tumor necrosis factor-${\alpha}$ converting enzyme (TACE). Lycopene found in tomatoes and tomato products has anti-oxidant, anti- cancer and anti-inflammatory effects. However, little is known about the effects of lycopene on EPCR shedding. We investigated this issue by monitoring the effects of lycopene on the phorbol-12-myristate 13-acetate (PMA), tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-$1{\beta}$ and on the cecal ligation and puncture (CLP)-mediated EPCR shedding. Data showed that lycopene potently inhibited the PMA, TNF-${\alpha}$, IL-$1{\beta}$ and CLP-induced EPCR shedding by suppressing TACE expression. Furthermore, lycopene reduced PMA-stimulated phosphorylation of p38, extracellular regulated kinases (ERK) 1/2 and c-Jun N-terminal kinase (JNK). Given these results, lycopene should be viewed as a candidate therapeutic agent for the treatment of various severe vascular inflammatory diseases via inhibition of the EPCR shedding.

• Wind and Structures
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• v.18 no.2
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• pp.181-194
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• 2014

A major problem with high-mast light poles is the effects that wind vortex shedding can have on the pole itself because of the lock-in phenomenon. It is desired that the coefficients in the AASHTO Standard Specifications ($5^{th}$ edition) for Structural Supports for Highway Signs, Luminaries, and Traffic Signals be analyzed and refined. This is for the belief that the span of the shapes of poles for which the coefficients are used is much too broad and a specific coefficient for each different shape is desired. The primary objective of this study is to develop wind vortex shedding coefficient for a multisided shape. To do that, an octagonal shape was used as the main focus since octagonal cross sectioned high-mast light poles are one of the most common shapes in service. For the needed data, many wind parameters, such as the static drag coefficient, the slope of aerodynamic lift coefficient, Strouhal number, the lock-in range of wind velocities producing vibrations, and variation of amplitude of vortex-induced vibration with Scruton number are needed. From wind tunnel experiments, aerodynamic parameters were obtained for an octagonal shape structure. Even though aerodynamic coefficients are known from past test results, they need to be refined by conducting further wind tunnel tests.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.193-200
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• 2008

We obtained quantitative information on leaf unfolding and leaf shedding by observing 45 species of cool temperate deciduous trees in an arboretum over 5 growing seasons. These trees were in leaf (the foliage period) for 207 days on average after 1 April; 50% of leaves had been shed by 192 days after 1 April. Duration from the start of leaf unfolding to 50% leaf shedding was 157 days on average. Leaf unfolding began 35 days on average after 1 April. For leaf unfolding to begin, a$ 51^{\circ}C{\cdot}day$ of cumulated daily mean air temperature above $5^{\circ}C$ from 1 January (modified Kira's warmth index) was needed. Fifty-nine days elapsed between initiation and the final stage of leaf unfolding. The period of net photosynthetic assimilation was 157 days. The species with succeeding- type leaf unfolding associated with the anemochore seed type dominated the early stage of succession, while the species with flush-type leaf unfolding tended to dominate the late stage of succession. Few species were found in regions where late frosts occur after the day when the cumulative temperature for leaf unfolding is achieved. Biological characteristics include time of leaf unfolding, which affects the life history of each species, so that each species occupies its own niche in the stand. We conclude that that leaf phenology, such as timing of leaf unfolding and leaf shedding, is one of the components of each species' ecological characteristics.