• The Journal of Information Systems
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• v.30 no.4
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• pp.43-69
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• 2021

Purpose Although companies occupied the network market take the advantageous position first and can be successful in securing users over a certain size, it is important to satisfy the customers' demand and prevent the outflow of users toward a new alternative SNS. What is more, there are frequent changes in the flow of users toward new SNSs. Despite these dynamic market circumstances, there is a lack of research to explain the switching behaviors of SNS users. Design/methodology/approach The objective of this study is to explain and verify a specified migration theory(Push-Pull-Mooring model) focused on SNS fatigue in the psychological point of view, as well as reviewing previous studies on functional and technical characteristics of SNSs themselves. Moreover, this study tried to highlight factors affecting users actual SNS switch rather than their switching intention. Findings According to the statistical analysis, the most influenced pull factor to switch SNS was the alternative attractiveness. On the other hand, undesired relationship burden, service innovation and important mooring factors to prevent users' SNS switch. This study has a significant contribution to the theory, which analyzed users' actual SNS switch, and examined SNS users' psychological factors(SNS fatigue), reviewing the characteristics of existing services. To secure more users and to keep them, companies providing social network service need to develop differentiated strategies by analyzing psychological characteristics of various users.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.221-221
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• 2020

Curcumin, a hydrophobic polyphenol derived from turmeric, has been used a food additive and as a herbal medicine for the treatment of various diseases. In the present study, we found the functional role of a nanosphere loaded with curcumin (CN) in the promotion of the motility of human umbilical cord blood derived mesenchymal stem cells (hUCB-MSCs) during the wound closure. We found that the efficacy of hUCB-MSCs migration induced by CN was 1000-fold higher than that of curcumin powder. CN significantly increased the motility of hUCB-MSCs by activating c-Src, which is responsible for the phosphorylation of protein kinase C (PKC) and extracellular signal-regulated kinase (ERK). CN induced the expression levels of α-actinin-1, profilin-1 and filamentous-actin, as regulated by the phosphorylation of nuclear factor-kappa B during its promotion of cell migration. In a mouse skin excisional wound model, we found that transplantation of UCB-MSCs pre-treated with CN enhances wound closure, granulation, and re-epithelialization at mouse skin wound sites. These results indicate that CN is a functional agent that promotes the mobilization of UCB-MSCs for cutaneous wound repair.

• Journal of Pharmacopuncture
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• v.26 no.4
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• pp.357-365
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• 2023

Objectives: Since stroke is a serious health issue, novel therapeutic strategies are required. In a mouse model of ischemic stroke, this study analyzed the potential of electroacupuncture (EA) and tenuigenin (TE) to improve the efficacy of human mesenchymal stem cell (hMSC) transplantation. Methods: Middle cerebral artery occlusion (MCAO) with reperfusion was used to generate ischemic stroke. Forty-eight male C57BL/6 mice were randomly divided into five groups: control, MCAO-operated, MCAO-EA, MCAO-TE, or MCAO + EA + TE. Subsequently, hMSCs were transplanted into the ischemic region and EA, TE, or the combination was administered. Behavior assessments and immunohistochemistry were conducted to evaluate motor and cognitive recovery and hMSCs survival, migration, and differentiation. Results: The combined treatment of EA and TE exhibited enhanced hMSCs survival, migration and differentiation into neural cell lineages while suppressing astrocyte formation. Immunohistochemistry demonstrated increased neurogenesis through hMSCs transplantation in the ischemic brain. Immediate behavioral improvements were not significantly different between groups, but there was a gradual recovery in motor and cognitive function over time. Conclusion: These findings highlight the potential of EA and TE co-treatment as a therapeutic strategy for ischemic stroke, opening avenues for further research to optimize treatment protocols and elucidate underlying mechanisms.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.178-184
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• 2002

For economy and convenience, seismic refraction survey is widely used in surveying for large civil engineering work. The purpose of this study is to obtain the numerical responses of various models using Kirchhoff migration, and to analyze its application to the real data processing. Synthetic traveltime curve was calculated by vidale's algorithm, and various models such as 2 or 3 layer model and irregular topography model are tested to simulate the response of real structure. In order to compare the effect of initial velocity model, true velocity models, inversion results by tomography, smooth velocity models are used as an initial guess. The responses of model data show that the algorithm of this study is more sensitive to initial velocity model than the reflection survey, so choosing a suitable initial velocity model will be the most important thing in real data processing.

• Journal of Korea Water Resources Association
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• v.50 no.5
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• pp.315-324
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• 2017

In this study, the HEC-GeoRAS model was used to estimate the changes of flood inundation depth and area of the Hyeoam-cheon basin after the channel migration and river improvement. The target area was extremely damaged due to the heavy rainfall on 25th August, 2014 after the costruction. According to the results of the analysis, the HEC-GeoRAS model can be used to accurately estimate the changes of flood innundation depth and area in agrecultural lands and lowlands of which the topographic changes and elevation differences are small. The inundation depths were increased 0.99 m in heavy rainfall and 0.39 m in 100 year frequency flood. The inundation areas in 100 year frequency flood were reduced in inundation depths under 1.5 m while they were increased in depths above 4.5 m. It was concluded that the loss of natural resevoir capacity of agricultural lands and lowlands due to the channel migration and river improvement caused the damage of flood in 2014 and the decrease of actual effective widths of the channel added the damage.

• Nutritional Sciences
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• v.7 no.3
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• pp.144-150
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• 2004

We have investigated the effect of calcium spirulan(Ca-SP) isolated from a blue-green alga Spirulina platensis, which is a sulfated polysaccharide chelating calcium and mainly composed of rhamnose and fructose, on invasion of both B16- BL6 melanoma cells, Colon 26 carcinoma and HT-1080 fibrosarcoma cells through reconstituted basement membrane (Matrigel). Ca-SP significantly inhibited the invasion of these tumor cells through Matrigel/fibronectin-coated filters in a concentration-dependent manner. Ca-SP also inhibited the haptotactic migration of tumor cells to laminin, but it had no inhibitory effect on tumor cell migration to fibronectin-coated filters. Ca-SP prevented the adhesion of B16-BL6 cells to Matrigel- and laminin-substrates but did not affect the adhesion to fibronectin. The pretreatment of tumor cells with Ca-SP inhibited the adhesion to laminin in a concentration-dependent fashion, while the pretreatment of laminin-substrates did not. Ca-SP had no effect on the production and activation of type IV collagenase in gelatin zymography. In contraset, Ca-SP significantly inhibited degradation of heparan sulfate by purified heparanase. The experimental lung metastasis was significantly reduced by co-injection of B16-BL6 cells with Ca-SP in a dose-dependent manner. Seven intermittent ⅰ.ⅴ. injection of 100$\mu\textrm{g}$ of Ca-SP caused a marked decrease of lung tumor colonization of B16-BL6 cells in a spontaneous lung metastasis model. These results suggest that Ca-SP, a novel sulfated polysaccharide, could reduce the lung colonization of B16-BL6 melanoma cells in experimental metastasis model, by inhibiting the tumor invasion of basement membrane Matrigel, probably through the prevention of the adhesion and migration of tumor cells to laminin-substrate and of the heparanase activity.

• Journal of Ginseng Research
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• v.47 no.1
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• pp.133-143
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• 2023

Background: Past studies suggested that ginseng extracts and ginseng-derived molecules exerted significant regulatory effects on skin. However, no reports have described the effects of ginseng-derived nanoparticles (GDNPs) on skin cell proliferation and wound healing. In this study, we investigated whether GDNPs regulate the proliferation of skin cells and promote wound healing in a mouse model. Methods: GDNPs were separated and purified via differential centrifugation and sucrose/D2O gradient ultracentrifugation. GDNP uptake, cell proliferation and cell cycle progression were measured by confocal microscopy, CCK-8 assay and flow cytometry, respectively. Cell migration and angiogenic effects were assessed by the wound scratch assay and tube formation assay, respectively. ELISA was used to detect extracellular matrix secretion. The relevant signaling pathway was confirmed by western blotting. The effects of GDNPs on skin wound healing were assessed by wound observation, HE staining, and western blotting. Results: GDNPs possessed the essential features of exosomes, and they were accumulated by skin cells. Treatment with GDNPs notably enhanced the proliferation of HaCaT, BJ and HUVECs. GDNPs also enhanced the migration in HaCaT cells and HUVECs and angiogenesis in HUVECs. GDNPs increased the secretion of MMP-1, fibronectin-1, elastin-1, and COL1A1 in all three cell lines. GDNPs regulated cell proliferation through the ERK and AKT/ mTOR pathways. Furthermore, GDNPs facilitated skin wound healing and decreased inflammation in a mouse skin wound model. Conclusion: GDNPs can promote skin wound healing through the ERK and AKT/mTOR pathways. GDNPs thus represent an alternative treatment for chronic skin wounds.

• Journal of the Korean association of regional geographers
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• v.11 no.4
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• pp.523-535
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• 2005

This study is aimed at researching the applicability of teaching-learning models in highschool geography class by designing the models on the basis of geographical experience the learners go through everyday life. The procedures and results of the application of the models are as followed. First, the systematization of the teaching concepts should be preceded to internalize the learners cognitive development, that is, to systemize cognitive structure. The concrete learning points of geographical concepts from the units about Migration and Population Changes are systemized with 'migration' as a higher concept, 'moving type' as basic concept, 'moving factors' as the lower concept. Everyday geographical experiences the students can go through are surveyed. Second, as preparation for the geography class, hand-outs about family-moving history and the change of the family number were used as basic material for real class teaching activity, showing the learners' general concepts are very effective as basic units which can be easily understood and accessed to. Third, with the experimental class, the geography class should secure the flexibility on the teaching-learning process. The result of applying the newly developed teaching-learning model to actual geography classes was that experimental group had higher achievement rate than the compared group with general teaching-learning model applied to. The result of analyzing students' response of the new teaching-learning model was that the students were interested and satisfied emphatically and they showed positive response in regard to practical use of the contents. Here, it is noticeable that the new teaching-learning model causes the students to be interested. But it's also found that there's no big difference in improving the students' inquisitive mind.

• Journal of Soil and Groundwater Environment
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• v.27 no.spc
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• pp.75-91
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• 2022

Differences in subsurface migration of LNAPL/DNAPL contaminants caused by a selection of 3-phase (aqueous, NAPL, and gas) relative permeability function (RPF) models in numerical modeling were investigated. Several types of RPF models developed from both experimental and theoretical backgrounds were introduced prior to conducting numerical modeling. Among the RPF models, two representative models (Stone I and Parker model) were employed to simulate subsurface LNAPLs/DNAPLs migration through numerical calculation. For each model, the spatiotemporal distribution of individual phases and the mole fractions of 6 NAPL components (4 LNAPL and 2 DNAPL components) were calculated through a multi-phase and multi-component numerical simulator. The simulation results indicated that both spilled LNAPLs and DNAPLs in the unsaturated zone migrated faster and reached the groundwater table sooner for Stone I model than Parker model while LNAPLs migrated faster on the groundwater table under Parker model. This results signified the crucial effect of 3-phase relative permeability on the prediction of NAPL contamination and suggested that RPF models should be carefully selected based on adequate verification processes for proper implementation of numerical models.

• Archives of Plastic Surgery
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• v.51 no.2
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• pp.163-168
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• 2024

Background The study determined to compare the clinical outcomes of traditional gold weight implantation for the correction of paralytic lagophthalmos with those of a newly designed model. Methods In this retrospective cohort study, we enrolled 30 patients (76% females; average age 60.8 ± 12 years) with facial palsy who underwent implantation of either the traditional pretarsal gold weight (PT group; n = 15) or a new supratarsal model (ST group; n = 15) from May 2014 to April 2019. The main outcome measures were the 12-month postoperative weight prominence, weight migration, improvement of lagophthalmos, upper eyelid contour, and upper eyelid ptosis. The secondary outcome was long-term (24 months) reoperative rate. Results The new model group had significantly better eyelid contour (risk ratio [RR] 3.16, 95% confidence interval [CI] 1.62-6.15, p = 0.001), less weight prominence (RR 1.74, 95% CI 1.13-2.70, p = 0.013), less weight migration (RR 1.31, 95% CI 1.12-1.54, p = 0.001), and less eyelid ptosis (RR 2.36, 95% CI 1.21-4.59, p = 0.011) than the traditional model group. Improvement of lagophthalmos was not statistically significant between the two groups (RR 1.44, 95% CI 0.72-2.91, p = 0.303). The 24-month reoperative rate was 53.3% in the PT group versus 13.3% in the ST group (RR 2.00, 95% CI 1.15-3.49, p = 0.015). Conclusion The newly designed supratarsal gold weight showed superior postoperative outcomes than the standard traditional model.