• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.4
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• pp.166-179
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• 2018

This study aims at numerically investigating the water-surface characteristics such as wave height distribution depending on the current direction around the three-dimensional permeable submerged breakwaters in wave-current coexisting field which has not been considered in detail so far. In addition, the characteristics of the velocity field including the average flow velocity, longshore current and turbulent kinetic energy, which act as the main external forces of formation of salient, are also examined. For numerical analysis, olaFlow which is open source code of CFD was used and the numerical tests included different types of target waves, both regular waves and irregular waves. Numerical results indicated that wave height variation with wave following or opposing a current behind the submerged breakwater is closely related to turbulent kinetic energy. Furthermore, it was found that weaker longshore currents are formed under wave-current coexisting field compared to the non-current conditions, and transport flow is attenuated. As a result, it was possible to understand the influence of current existence and direction (following and opposing) on the formation of the salient formed behind the submerged breakwaters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.1-10
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• 2020

The application of multiphase flows is increasingly being applied to analyze phenomena such as single phase flows where the fluid boundary changes continuously over time or the problem of mixing a liquid phase and a gas phase. In particular, multiphase flow models that take into account incompressible Newtonian fluids for liquid and gas are often applied to solve the problems of the free water surface such as wave fields. In general, multi-phase flow models require time-based the surface tracking of each fluid's phase boundary, which determines the accuracy of the final calculation of the model. This study evaluates the advection performance of representative VOF-type boundary tracking techniques applied to various CFD numerical codes. The effectiveness of the FCT method to control the numerical flux to minimize the numerical diffusion in the conventional VOF-type boundary tracking method and advection calculation was mainly evaluated. In addition, the possibility of tracking performance of free surface using CIP method (Yabe and Aoki, 1991) was also investigated. Numerical results show that the FCT-VOF method introducing an anti-diffusive flux to precent excessive diffusion is superior to other methods under the confined conditions in this study. The results from this study are expected to be used as an important basic data in selecting free surface tracking techniques applied to various numerical codes.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1446-1451
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• 2016

Clostridium difficile toxin A causes acute gut inflammation in animals and humans. It is known to downregulate the tight junctions between colonic epithelial cells, allowing luminal contents to access body tissues and trigger acute immune responses. However, it is not yet known whether this loss of the barrier function is a critical factor in the progression of toxin A-induced pseudomembranous colitis. We previously showed that NADH:quinone oxidoreductase 1 (NQO1) KO (knockout) mice spontaneously display weak gut inflammation and a marked loss of colonic epithelial tight junctions. Moreover, NQO1 KO mice exhibited highly increased inflammatory responses compared with NQO1 WT (wild-type) control mice when subjected to DSS-induced experimental colitis. Here, we tested whether toxin A could also trigger more severe inflammatory responses in NQO1 KO mice compared with NQO1 WT mice. Indeed, our results show that C. difficile toxin A-mediated enteritis is significantly enhanced in NQO1 KO mice compared with NQO1 WT mice. The levels of fluid secretion, villus disruption, and epithelial cell apoptosis were also higher in toxin A-treated NQO1 KO mice compared with WT mice. The previous and present results collectively show that NQO1 is involved in the formation of tight junctions in the small intestine, and that defects in NQO1 enhance C. difficile toxin A-induced acute inflammatory responses, presumably via the loss of epithelial cell tight junctions.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1629-1635
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• 2012

Previously, we demonstrated that the erythropoietin receptor (EpoR) is present on fibroblasts, where it regulates focal contact. Here, we assessed whether this action of EpoR is involved in the reduced cell adhesion observed in colonocytes exposed to Clostridium difficile toxin A. EpoR was present and functionally active in cells of the human colonic epithelial cell line HT29 and epithelial cells of human colon tissues. Toxin A significantly decreased activating phosphorylations of EpoR and its downstream signaling molecules JAK-2 (Janus kinase 2) and STAT5 (signal transducer and activator of transcription 5). In vitro kinase assays confirmed that toxin A inhibited JAK 2 kinase activity. Pharmacological inhibition of JAK2 (with AG490) abrogated activating phosphorylations of EpoR and also decreased focal contacts in association with inactivation of paxillin, an essential focal adhesion molecule. In addition, AG490 treatment significantly decreased expression of occludin (a tight junction molecule) and tight junction levels. Taken together, these data suggest that inhibition of JAK2 by toxin A in colonocytes causes inactivation of EpoR, thereby enhancing the inhibition of focal contact formation and loss of tight junctions known to be associated with the enzymatic activity of toxin A.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.186-192
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• 2005

We investigated the deposition characteristics and mass transport flux estimation of the Nakdong estuary, Korea. To understand the effects of the tidal current circulation that influences estuary terrain changes, we used a 2D numerical model to map seawater circulation under three different situations, with the level of river flow being set as none or flood. The net-water flux of the cross-sectional area between sandbars (known as dung) was estimated. From our review of previous research, we know that the development of local sandbars shifted from the west to the east side of the estuary after the construction of the Nakdong River dike. Current development is occurring mostly at the Bakhap-dung near Tadea. The seawater circulation pattern over this large-scale area of tidal na is brings changes related to the quantity of the outflow from the Nakdong River. Based on the calculated results for the net-water flux of the cross-sectional area, we see very strong accumulation in local waters around Jangjiado, Bakhapdung, and Tadae under flood river flow conditions, but accumulation in local waters around Jinudo under the other states of flow. Consequently, in the Nakdong estuary, the main sensitive regions that are affected by changes in the flow of river discharge are the local waters around Jangiado, Bakhapdung, Tadae, and Jinudo.

• Korean Journal of Environmental Agriculture
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• v.7 no.1
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• pp.1-7
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• 1988

In order to clarify how much of the residues of Bentazon could be taken up by crops, soybean and radish were grown for 28 days in soils containing freshly treated $^{14}C-Bentazon$ and non-extractable soil-hound residues of $^{14}C-Bentazon.$ The results obtained are summarized as follows. 1. $^{14}CO_2$ evolution from $^{14}C$-Bentazon during the 6-month pre-incubation in soil was 14.79% relative to the applied radioactivity. 2. Mineralization of ^$^{14}C$-Bentazon in soil to $^{14}CO_2$ during 28 days of crop growing was much higher in the freshly treated soil than in the bound soil, and much higher in radish than in soybean. 3. The amounts of $^{14}C-Bentazon$ and its metabolites absorbed by soybean and radish were 45.41 and 21.48%, respectively, in freshly treated soil, whereas those were 3.92 and 1.23% in bound soil, respectively. The translocation ratios of radioactivity .from the root to the shoot were much higher in radish than in soybean, remarkably. 4. The uptake ratios of the freshly treated $^{14}C-Bentazon$ to the bound $^{14}C-Bentazon$ by soybean and radish were 12 : 1 and 17 : 1, respectively. 5. It was well verified that the presence of crops enhanced the mineralization to $^{14}CO_2$ and the transformation to polar metabolites of Bentazon.

• Korean Journal of Animal Reproduction
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• v.15 no.1
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• pp.59-66
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• 1991

This study was carried out to investigate the length of the estrous cycle and duration of estrus in Korean native goats. The effects of the type of last estrus : induced or natural, and the length of preceeding estrous cycle on the subsequent cycle and duration of estrus in goats were also examined. From 481 observations, the mean length of estrous cycles was 18.1${\pm}$0.5days. The cycle length was significantly(P<0.05) shorter following induced estrus (15.2${\pm}$0.8 d) than natural estrus(19.0${\pm}$0.6 d). Significantly higher(P<0.05) incidence of short estrous cycle was observed following induced estrus(40%) than natural estrus(27%). The frequency distribution in the estrous cycle was 30%, 3%, 56% and 11% for short(3-11 d), medium(12-16 d), normal(17-24 d) and long(${\geqq}$25 d), respectively. The most frequent type of short estrous cycle was 6 days in length. Mean duration of estrus was 34.0${\pm}$0.5 h with a range of 18 to 84 h. Duration of estrus was not significantly different the preceeding natural (33.8${\pm}$0.6 h) and induced estrus (34.4${\pm}$1.1 h), and was not significantly affected by the last cycle length. These results suggest that the short estrus cycles are more frequent following induced estrus than natural one, and the duration of estrus are affected greatly by the various intrinsic and extrinsic factors.

• Journal of Animal Science and Technology
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• v.50 no.3
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• pp.309-314
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• 2008

The objective of this study was to estimate effects of the condition of racetrack on racing time in Thoroughbred racehorses, using 148,865 racing records for 8,189 heads that collected from KRA(Korea Racing Association). The results obtained were as follows. Based on moisture contents, the condition of racetrack was classified into Heavy, Good, Soft, Yielding and Sloppy. The condition of racetrack for last 12 years was 40.7%, 34.4%, 14.4%, 8.7% and 1.8% for Heavy, Good, Soft, Yielding and Sloppy, respectively. The frequency of heavy condition for racetrack was the highest and those of Yielding and Sloppy were relatively low. On the other hand, the frequency of heavy condition for racetrack was increased in spring and winter, whereas frequency of sloppy racetrack was increased in summer. The frequency of good condition was the highest in autumn. The regression coefficients of moisture contents in racetrack for racing time by racing distance ranged from －0.068~－0.162 seconds and the racing time was faster in sloppy condition than other track conditions. The time differences between Heavy and Sloppy ranged from －1.47~－3.41 seconds by distance.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.239-247
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• 1995

The improvement of distribution system and freshness prolongation of crisphead lettuce were carried out through vacuum cooling and distribution under the low temperature. Lettuce that vacuum-cooled and transported by cold storage car was shown better freshness than that distributed by conventional method when they arrived at cunsuming area. And it took $10{\sim}17$ hours until their temperatures arrived at same temperatures when they were stored at $0{\sim}15^{\circ}C$ cold storage room. It was cooled to $1^{\circ}C$ after 27 minutes with vacuum cooling apparatus. The weight loss of lettuce that vacuum cooled and transported by cold storage car was below 5% after 30 days cold storage. And ascorbic acid and chlorophyll retentions were 86% and 52%, respectively. The shelf-life of crisphead lettuce, distributed by vacuum cooling and cold storage car transportation, was 5 days at $15^{\circ}C$ and over 40 days at $0^{\circ}C$, respectively. However, when it was distributed by conventional method, it was only 3 days at $15^{\circ}C$ and 20 days at $0^{\circ}C$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1133-1138
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• 2010

The purpose of our study was to evaluate the correlation between expression of VEGF, HIF-$1{\alpha}$, E-cadherin, and p53 and pathologic stage. We retrospectively reviewed the medical records of the 101 patients who underwent surgery of thyroid nodules from 2000 to 2007. Expression of VEGF, HIF-$1{\alpha}$, E-cadherin, and p53 were examinated immunohistochemically. Papillary thyroid carcinoma in this study included 54 cases of more than 45 years old. Each expression of VEGF, HIF-$1{\alpha}$, E-cadherin, and p53 was analysed. Only expression loss of E-cadherin was associated with the stage. High HIF-1 expression was significantly associated with VEGF immunoreactivity (p<0.05). Expression loss of E-cadherin was independent unfavorable factors. It is suggested that high HIF-$1{\alpha}$ expression may be associated with intratumoral neovascularization possibly through HIF-VEGF pathway.