• Journal of Korea Water Resources Association
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• v.52 no.10
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• pp.743-752
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• 2019

The flow in the meandering channel is characterized by the spiral motion of secondary currents that typically cause the erosion along the outer bank. Hydraulic structures, such as spur dike and groyne, are commonly installed on the channel bottom near the outer bank to mitigate the strength of secondary currents. This study is to investigate the effects of submerged vanes installed in a $90^{\circ}$ meandering channel on the development of secondary currents through three-dimensional numerical modeling using the hybrid RANS/LES method for turbulence and the volume of fluid method, based on OpenFOAM open source toolbox, for capturing the free surface at the Froude number of 0.43. We employ the second-order-accurate finite volume methods in the space and time for the numerical modeling and compare numerical results with experimental measurements for evaluating the numerical predictions. Numerical results show that the present simulations well reproduce the experimental measurements, in terms of the time-averaged streamwise velocity and secondary velocity vector fields in the bend with submerged vanes. The computed flow fields reveal that the streamwise velocity near the bed along the outer bank at the end section of bend dramatically decrease by one third of mean velocity after the installation of vanes, which support that submerged vanes mitigate the strength of primary secondary flow and are helpful for the channel stability along the outer bank. The flow between the top of vanes and the free surface accelerates and the maximum velocity of free surface flow near the flow impingement along the outer bank increases about 20% due to the installation of submerged vanes. Numerical solutions show the formations of the horseshoe vortices at the front of vanes and the lee wakes behind the vanes, which are responsible for strong local scour around vanes. Additional study on the shapes and arrangement of vanes is required for mitigate the local scour.

• Korean Journal of Plant Resources
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• v.32 no.4
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• pp.312-317
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• 2019

This study was conducted with the purpose of examining the suitability of Euphorbia jolkinii Boiss. as cut flower, so that it may be introduced as a new ornamental crop. For this purpose, effect of various holding solutions on vase solution uptake rate, vase life, and relative fresh weight of cut flowering branches of E. jolkinii was examined. After harvest, cut branches were treated with 10, 50, and $100mg{\cdot}L^{-1}$ of 8-hydroxyquinoline sulfate (8-HQS), 0.1 and 0.2 mM of silver thiosulfate (STS), Chrysal, and Floralife. The cut branches of E. jolkinii were placed under the environmental conditions maintained at air temperature of $22.6^{\circ}C$, relative humidity of 45%, and 9/15h photoperiod that was controlled using fluorescent lamps (light intensity of $9.89{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). A holding solution containing $10mg{\cdot}L^{-1}$ 8-HQS was found to be significantly effective for vase solution uptake rate compared to control, $50mg{\cdot}L^{-1}$ 8-HQS, and $100mg{\cdot}L^{-1}$ 8-HQS treatments. However, no significant difference was found in vase life between the branches treated with $10mg{\cdot}L^{-1}$ 8-HQS holding solution and branches of the control group. Increasing holding solution concentrations of STS was found to have negative effect on the vase life of cut E. jolkinii branches. Relative fresh weight of cut E. jolkinii branches were significantly decreased by two commercial holding solutions, Chrysal and Floralife. It is expected that these results would aid further studies on utilization of E. jolkinii as cut flower crop.

• Journal of Life Science
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• v.31 no.2
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• pp.229-236
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• 2021

This study was carried out to evaluate the antioxidant properties of the dried leaves and branches of Stewartia koreana Nakai. The dried leaf and branch of S. koreana were extracted with 70% ethanol at 80℃. The antioxidant activities of ethanol extracts of S. koreana leaf (EESL) and S. koreana branch (EESB) were analyzed. The total polyphenol contents in EESL and EESB were 162.57±0.9 mg of GAEs/extract g and 59.1±0.9 mg of GAEs/extract g, respectively. The flavonoid contents in EESL and EESB were 59.1±0.9 mg of QEs/extract g and 4.7±0.1 mg of QEs/extract g, respectively. EESL showed a better scavenging ability with DPPH and ABTS than EESB, at 0.4 mg/ml. Moreover, EESL were more effective according to ORAC values than EESL. The toxicity of EESL was investigated using a WST-1 assay on the human skin fibroblast cell line CCD-986sk. Therefore, EESL can be used as a potential source of functional, naturally-sourced material in cosmetics as well as food.

• Journal of Life Science
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• v.31 no.2
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• pp.199-208
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• 2021

Euonymus porphyreus, a species of plant in the Celastraceae family, is widely distributed in East Asia, especially in Southern China. The botanical characteristics of E. porphyreus have been reported, but its antioxidative and anticancer activities remain unclear. In this study, we evaluated the antioxidative and anticancer effects of ethanol extracts of E. porphyreus (EEEP) and the molecular mechanism of its anticancer activity in human lung adenocarcinoma A549 cells. The total polyphenol and flavonoid compound contents from EEEP were 115.42 mg/g and 23.07 mg/g, respectively. EEEP showed significant antioxidative effects with a concentration at 50% of the inhibition (IC50) value of 11.09 ㎍/ml, as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. EEEP showed cytotoxic activity by increasing the SubG1 cell population of A549 cells in a dose-dependent manner. Apoptosis in A549 cells treated with EEEP was evident due to increased apoptotic cells and apoptotic bodies, as detected by Annexin V and 4,6-diamidino-2-phenylindole (DAPI) staining, respectively. EEEP-induced apoptosis resulted in increased expression of the First apoptosis signal (Fas), p53, and Bax, with decreased expression of Bcl-2 and subsequent activation of caspase-8, -9, and caspase-3, leading to cleavage of poly (ADP-ribose) polymerase (PARP). Collectively, these results suggest that EEEP may exert an anticancer effect by inducing apoptosis in A549 cells through both intrinsic and extrinsic pathways.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.4
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• pp.53-68
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• 2020

The concentrations of ammonia, hydrogen sulfide and fine dust were measured in the compost facility of a full-time Hanwoo breeding farms. The experiments were conducted in stack type composting facility(T1) and mechanical-stirred composting facilities(T2, T3). In the stack type composting facility, the highest temperature of compost pile was 46℃, and in the two mechanical-stirred composting facilities, it rose to 63℃ and 68℃, respectively. The concentrations of PM2.5 at T1, T2 were 15 ㎍/㎥ and 5~10 ㎍/㎥, respectively. And the concentration of PM2.5 at T3 was below 10 ㎍/㎥. The highest concentration of ammonia generated at T1 was 4 ppm, but no hydrogen sulfide was detected. The ammonia concentrations at T2 and T3 were 3 ppm and 4 ppm, respectively. However, hydrogen sulfide was not detected in both facilities. At T3, the ammonia concentration increased to 65 ppm at the point where the compost was stirred with a mechanical agitator. During composting period, the pH of the compost pile decreased from 9.06 to 8.94 and then increased to 9.14 as the composting period elapsed. The NaCl content of compost was 0.09% after composting process was complete. Moisture content of compost decreased from 65.9% to 62% as composting progressed. As composting proceeded, the content of volatile solids decreased from 65.6% to 64.7% and the content of TKN decreased from 1.327% to 1.095%.

• Journal of Life Science
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• v.31 no.3
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• pp.298-304
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• 2021

The anti-aging and anti-inflammatory activities of hot-water (Ca-HW) and 70% ethanol (Ca-E70) whole-plant Calamagrostis arundinacea extracts, as well as their bioactive potentials, were investigated using cell-free and cell-mediated experimental systems. Use of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical decolorization assay to evaluate the antioxidant activity of the Ca-HW and Ca-E70 extracts revealed DPPH radical scavenging activities of 27% and 48%, respectively. Neither extract caused significant cytotoxicity, and both showed cell proliferation and promotion effects using RAW 264.7, B16F10, and CCD986sk cells. B16F10 melanoma cells showed higher melanin synthesis when treated with 100 mg/ml Ca-HW or Ca-E70 than with arbutin, indicating a stronger inhibitory effect of arbutin on melanin synthesis. Ca-HW and Ca-E70 increased pro-collagen biosynthesis in the human fibroblast CCD986-SK cell line by 24.69% and 12.55%, respectively. Analysis of the anti-inflammatory effects of different concentrations of Ca-HW and Ca-E70 in RAW264.7 cells revealed that Ca-E70 appeared to inhibit the lipopolysaccharide-induced production of nitric oxide and IL-6, a proinflammatory cytokine; therefore, Ca-E70 showed an anti-inflammatory effect. These results suggested that C. arundinacea extracts could have skin anti-aging and anti-inflammatory properties.

• Journal of the Korean Geotechnical Society
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• v.37 no.3
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• pp.19-30
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• 2021

The presence of the hydrate-bearing sediments in Ulleung Basin of South Korea has been confirmed from previous studies. Researches on gas production methods from the hydrate-bearing sediments have been conducted worldwide. As production mechanism is a complex phenomenon in which thermal, hydraulic, and mechanical phenomena occur simultaneously, it is difficult to accurately conduct the productivity and stability analysis of hydrate bearing sediments through lab-scale experiments. Thus, the importance of numerical analysis in evaluating gas productivity and stability of hydrate-bearing sediments has been emphasized. In this study, the numerical parametric analysis was conducted to investigate the effects of the bottom hole pressure and the depressurization rate on the gas productivity and stability of hydrate-bearing sediments during the depressurization method. The numerical analysis results confirmed that as the bottom hole pressure decreases, the productivity increases and the stability of sediments deteriorates. Meanwhile, it was shown that the depressurization rate did not largely affect the productivity and stability of the hydrate-bearing sediments. In addition, sensitivity analysis for gas productivity and stability of the sediments were conducted according to the depressurization rate in order to establish a production strategy that prevents sand production during gas production. As a result of the analysis, it was confirmed that controlling the depressurization rate from a low value to a high value is effective in securing the stability. Moreover, during gas production, the subsidence of sediments occurred near the production well, and ground heave occurred at the bottom of the production well due to the pressure gradient. From these results, it was concluded that both the productivity and stability analyses should be conducted in order to determine the bottom hole pressure when producing gas using the depressurization method. Additionally, the stress analysis of the production well, which is induced by the vertical displacements of sediments, should be evaluated.

• Journal of Life Science
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• v.31 no.3
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• pp.257-265
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• 2021

Heterotrimeric kinesin-2 is a molecular motor protein of the kinesin superfamily (KIF) that moves along a microtubule plus-end directed motor protein. It consists of three different motor subunits (KIF3A, KIF3B, and KIF3C) and a kinesin-associated protein 3 (KAP3) that form a heterotrimeric complex. Heterotrimeric kinesin-2 interacts with many different binding proteins through the cargo-binding domain of the KIF3s. The activity of heterotrimeric kinesin-2 is regulated to ensure that the cargo is directed to the right place at the right time. How this regulation occurs, however, remains in question. To identify the regulatory proteins for heterotrimeric kinesin-2, we performed yeast two-hybrid screening and found a specific interaction with creatine kinase B (CKB), which is the brain isoform of cytosolic creatine kinase enzyme. CKB bound to the cargo-binding domain of KIF3A but did not interact with the KIF3B, KIF5B, or KAP3 in the yeast two-hybrid assay. The carboxyl (C)-terminal region of CKB is essential for the interaction with KIF3A. Another protein kinase, CaMKIIa, interacted with KIF3A, but GSK3a did not interact with KIF3A in the yeast two-hybrid assay. KIF3A interacted with GST-CKB-C but not with GSK-CKB-N or GST alone. When co-expressed in HEK-293T cells, CKB co-localized with KIF3A and co-immunoprecipitated with KIF3A and KIF3B but not KIF5B. These results suggest that the CKB-KIF3A interaction may regulate the cargo transport of heterotrimeric kinesin-2 under energy-compromised conditions in cells.

• Journal of Life Science
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• v.31 no.3
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• pp.330-337
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• 2021

This study was conducted to investigate the potential of Stewartia koreana as oral healthcare materials. The antibacterial activity of ethanol extracts from leaves and branches of S. koreana against oral bacteria was confirmed. The leaf and branch extracts (1 mg/disc) showed antibacterial activity against P. gingivalis only among several tested oral bacteria. The leaf extracts showed higher antibacterial activity, with values similar to those of chlorhexidine, which was used as a positive control. The MIC of the leaf extract against P. gingivalis was 0.4 mg/ml and showed bacteriostatic action. The inhibitory effects of the extract on biofilm formation and on gene expression related to biofilm formation by P. gingivalis were determined by biofilm biomass staining, scanning electron microscopy (SEM), and qRT-PCR analysis. The biofilm production rate and cell growth of P. gingivalis in the cultures treated with 0.2-2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. The inhibitory effect on the formation of P. gingivalis biofilms at concentrations of 1 mg/ml was confirmed by SEM. The qRT-PCR analysis showed concentration-dependent suppression of the fimA and fimB gene expression associated with fimbriae formation in the cultures treated with 0.2-2.0 mg/ml S. koreana leaf extract. These results support the conclusion that S. koreana leaf extracts can be used as oral healthcare materials derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. gingivalis.

• Korean Journal of Psychosomatic Medicine
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• v.28 no.2
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• pp.161-167
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• 2020

Objectives : Although the seasonality of suicide is a well-known phenomenon, little is reported about the seasonality of non-suicidal self-injury. The purpose of this study was to identify the seasonality of wristcutting behavior and to examine its relationship with meteorological factors. Methods : To identify the presence of seasonality, we investigated whether there was a difference in the average number of visits per month to an emergency room (ER) of an urban hospital for 226 patients with wrist-cutting behavior enrolled between December 2014 and May 2019. To ascertain significant meteorological factors, we used the multiple Poisson regression using generalized additive model with time, monthly temperature, monthly sunshine hour, and atmospheric pressure in the prior month as explanatory variables. Results : In males, the average number of monthly visits to the ER for wrist cutting behavior differed by month and was the highest in September (male : p=0.048, female : p=0.21, total : p=0.28). As a result of multiple regression analysis, the average number of patients admitted to the ER for wrist cutting behavior was related to the interaction between atmospheric pressure in the prior month and temperature in males (p=0.010), and showed a positive correlation with sunlight in females [p=0.044, β=4.70×10-3, 95% CI=(1.19×10-4, 9.27×10-3)]. Conclusions : Wrist cutting behavior shows seasonality in male, which is associated with changes in meteorological variables.