• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.181-189
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• 2017

This study examines whether the variables used in the Unified Theory of Acceptance and Use of Technology(performance expectancy, effort expectancy, social influence, and facilitating conditions) is applicable to continuous usage of uTradeHub at a time of expansion in the use of uTradeHub. In addition, the role of user satisfaction(mediating effect) and CEO support(interaction effect) in the relationship is identified attempting to provide basic data to help uTradeHub management strategy establishment. A total of 101 valid responses collected through questionnaires were used for empirical analysis(using SPSS 24.0), and the results are as follows. First, for the effect of the integration technology acceptance factor on user satisfaction(H1), only performance expectancy, effort expectancy, and social influence were significant, but facilitating conditions was not significant. Second, for the effect of user satisfaction on the continued use of uTradeHub(H2), there was a significant result. Third, the mediation effect on verification of user satisfaction(H3) was full where performance expectancy, effort expectancy, and social influence prompted continuous usage through user satisfaction. Fourth, for interactive effect verification of CEO support(H4), an interaction effect was shown only in the influence relationship of performance expectancy and social influence on user satisfaction.

• Journal of the Korean Geotechnical Society
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• v.29 no.10
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• pp.49-56
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• 2013

The use of geothermal energy has been increased for economic and environmental friendly utilization. Ground thermal conductivity and borehole thermal resistance are very important parameters in the design of geothermal heat pump system. This paper presents an experimental study of heat exchange rate of U and W type ground heat exchangers (GHEs) measured by thermal performance tests (TPTs). U and W type GHEs were installed in a partially saturated dredged soil deposit, and TPTs were conducted to evaluate heat exchange rates under 100-hr continuous operation condition. The heat exchange rates were also calculated by analytical models to estimate borehole thermal resistances and were compared with experimental results. It comes out that multi-pole and equivalent diameter (EQD) models resulted in more accurate agreement than shape factor (SF) model which is currently more often used.

• Biomolecules & Therapeutics
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• v.28 no.2
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• pp.152-162
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• 2020

Cerebral ischemia exhibits a multiplicity of pathophysiological mechanisms. During ischemic stroke, the reactive oxygen species (ROS) concentration rises to a peak during reperfusion, possibly underlying neuronal death. Recombinant human erythropoietin (EPO) supplementation is one method of treating neurodegenerative disease by reducing the generation of ROS. We investigated the therapeutic effect of PEGylated EPO (P-EPO) on ischemic stroke. Mice were administered P-EPO (5,000 U/kg) via intravenous injection, and middle cerebral artery occlusion (MCAO) followed by reperfusion was performed to induce in vivo ischemic stroke. P-EPO ameliorated MCAO-induced neurological deficit and reduced behavioral disorder and the infarct area. Moreover, lipid peroxidation, expression of inflammatory proteins (cyclooxygenase-2 and inducible nitric oxide synthase), and cytokine levels in blood were reduced by the P-EPO treatment. In addition, higher activation of nuclear factor kappa B (NF-κB) was found in the brain after MCAO, but NF-κB activation was reduced in the P-EPO-injected group. Treatment with the NF-κB inhibitor PS-1145 (5 mg/kg) abolished the P-EPO-induced reduction of infarct volume, neuronal death, neuroinflammation, and oxidative stress. Moreover, P-EPO was more effective than EPO (5,000 U/kg) and similar to a tissue plasminogen activator (10 mg/kg). An in vitro study revealed that P-EPO (25, 50, and 100 U/mL) treatment protected against rotenone (100 nM)-induced neuronal loss, neuroinflammation, oxidative stress, and NF-κB activity. These results indicate that the administration of P-EPO exerted neuroprotective effects on cerebral ischemia damage through anti-oxidant and anti-inflammatory properties by inhibiting NF-κB activation.

• Biomolecules & Therapeutics
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• v.6 no.4
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• pp.383-388
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• 1998

The present study was aimed to investigate the preventive effects of rebamipide on the multiple organ dysfunction in a rat model of circulatory shock induced by bacterial endotoxin (E. coli lipopolysaccharide; LPS) in comparison with that of methotrexate. Endotoxemia for 6 hours resulted in little change in the levels of hemoglobin and neutrophils. However, treatment with methotrexate decreased significantly the numbers of circulating neutrophils. Significant increases in serum alanine aminotransferase (ALT,958 $\pm$ 250 lU/L, p<0.001) and aspartate aminotransferase (AST, 1350 $\pm$ 295 lU/L, p<0.001) levels induced by endotoxemia were significantly decreased by rebamipide and methotrexate. The increased level of lactic acid dehydrogenase (LDH) by LPS (2850 $\pm$ 467 lU/L, p<0.05) was significantly inhibited by rebamipide, but not by methot.elate. The elevated serum creatinine (1.2$\pm$0.1, p.0.05) and urea levels (55.3$\pm$6.5 mg/dL, p.0.01) by LPS were also decreased by rebamipide, but not by methotrexate. In line with these results, the plasma concentration of tumor necrosis factor-$\alpha$ (TNF-7,167 $\pm$ 20 pg/mL) was significantly increased upon injection of endotoxin at 1 hour by 1570$\pm$100 pg/mL, and declined to 312$\pm$35 pg/mL at 6 hours. The TNF-$\alpha$ level at 6 hours was significantly decreased by rebamipide to 207$\pm$8 pg/mL (P<0.05). Taken together, it is summarized that rebamipide inhibits the development of multiple ogran dysfunction by inhibition of neutrophil activation in association with inhibition of TNF-$\alpha$ formation in a murine model of endotoxemia.

• Journal of Korean Neurosurgical Society
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• v.63 no.4
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• pp.444-454
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• 2020

Objective : Glioblastoma multiforme (GBM) is the most aggressive for of brain tumor and treatment often fails due to the invasion of tumor cells into neighboring healthy brain tissues. Activation of the Janus kinase-signal transducer and activator of transcription (JAK/STAT) signaling pathway is essential for normal cellular function including angiogenesis, and has been proposed to have a pivotal role in glioma invasion. This study aimed to determine the dose-dependent effects of ruxolitinib, an inhibitor of JAK, on the interferon (IFN)-I/IFN-α/IFN-β receptor/STAT and IFN-γ/IFN-γ receptor/STAT1 axes of the IFN-receptor-dependent JAK/STAT signaling pathway in glioblastoma invasion and tumorigenesis in U87 glioblastoma tumor spheroids. Methods : We administered three different doses of ruxolitinib (50, 100, and 200 nM) to human U87 glioblastoma spheroids and analyzed the gene expression profiles of IFNs receptors from the JAK/STAT pathway. To evaluate activation of this pathway, we quantified the phosphorylation of JAK and STAT proteins using Western blotting. Results : Quantitative real-time polymerase chain reaction analysis demonstrated that ruxolitinib led to upregulated of the IFN-α and IFN-γ while no change on the hypoxia-inducible factor-1α and vascular endothelial growth factor expression levels. Additionally, we showed that ruxolitinib inhibited phosphorylation of JAK/STAT proteins. The inhibition of IFNs dependent JAK/STAT signaling by ruxolitinib leads to decreases of the U87 cells invasiveness and tumorigenesis. We demonstrate that ruxolitinib may inhibit glioma invasion and tumorigenesis through inhibition of the IFN-induced JAK/STAT signaling pathway. Conclusion : Collectively, our results revealed that ruxolitinib may have therapeutic potential in glioblastomas, possibly by JAK/STAT signaling triggered by IFN-α and IFN-γ.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1938-1944
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• 2008

The procpb gene encoding human procarboxypeptidase B (proCPB, GeneBank access code AJ224866) was cloned and its Pichia expression plasmid, $pPIC9{\alpha}$/hproCPB (9.2 kb), was constructed, in which procpb was under the control of the AOXl promoter and connected to the downstream of the mating factor ${\alpha}$-1 ($MF{\alpha}1$) signal sequence. The plasmid was linearized by digestion with Sacl, and integrated into the genome of P. pastoris strain GS115. By culturing of Pichia transformant on methanol medium, the human proCPB was successfully expressed and secreted into the culture supernatant. Moreover, Western blot analysis of the extracellular proteins showed proCPB bands clearly at a molecular mass of 45 kDa, confirming the expression of proCPB with its right size. The CPB activity reached about 3.5 U/ml and 12.7 U/ml in the flask and fermentor batch cultures of Pichia transformant, respectively. No CPB enzyme activity was found in the intracellular fraction. When the fed-batch cultivation was performed with methanol and glycerol mixture as a feeding medium, the extracellular CPB activity was increased to 42.0 U/ml, which corresponds to a 3.3-fold higher level of CPB activity than that of batch culture. The $K_m$ and $k_{cat}$ values of recombinant human CPB enzyme for hippuryl-$_L$-Arg as a substrate were estimated to be 0.16 mM and $11.93\;sec^{-1}$, respectively.

• Journal of Periodontal and Implant Science
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• v.44 no.6
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• pp.274-279
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• 2014

Purpose: To evaluate whether the levels of immunoglobulin G (IgG) antibody to Tanerella forsythia are associated with periodontal status. Methods: Patients with a diagnosis of chronic periodontitis were considered candidates for the study; thus 80 chronic periodontitis patients and 28 healthy persons (control group) were invited to participate in this investigation. The presence of T. forsythia was detected by polymerase chain reaction (PCR) analysis using primers designed to target the respective 16S rRNA gene sequences. Peripheral blood was collected from each subject to identify the IgG1 and IgG2 serum antibodies against T. forsythia. All microbiological and immunological laboratory processes were completed blindly, without awareness of the clinical status of the study patients or of the periodontal sites tested. Results: The bivariate analysis showed that lower mean levels of clinical attachment level (CAL) and probing depth were found in the presence of the IgG1 antibody titers against whole-cell T. forsythia; however, only the difference in CAL was statistically significant. In the presence of the IgG2 antibody titers against whole-cell T. forsythia, the periodontal parameters evaluated were higher but they did not show statistical differences, except for plaque. The unadjusted linear regression model showed that the IgG1 antibody against whole-cell T. forsythia in periodontitis patients was associated with a lower mean CAL (${\beta}=-0.654$; 95% confidence interval [CI], -1.27 to -0.28; P<0.05). This statistically significant association remained after adjusting for possible confounders (${\beta}=-0.655$; 95% CI, -1.28 to -0.29; P<0.05). On the other hand, smoking was a statistically significant risk factor in the model (${\beta}=0.704$; 95% CI, 0.24 to 1.38; P<0.05). Conclusions: Significantly lower mean levels of CAL were shown in the presence of the IgG1 antibody titers against whole-cell T. forsythia in periodontitis patients. Thus, the results of this study suggest that IgG1 antibody to T. forsythia may have been a protective factor from periodontitis in this sample.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.524-529
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• 2015

This study was conducted to optimize the medium composition for cold-adaptive protease production of Enterobacteriaceae sp. by response surface methodology (RSM). Yeast extract, and TritonX-100 were identified as the significant factors affecting protease from one-factor-at-a-time method. RSM studies for optimizing protease production of Enterobacteriaceae sp. have been carried out for three parameters including yeast extract concentration, TritonX-100 concentration, and culture pH. These significant factors were optimized as 6.690 g/L yeast extract, 0.018 g/L Triton$^{TM}$ X-10, and pH 6.677. The experimentally obtained protease activity was 8.03 U /L, and it became 1.5-fold increase before optimization.

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.65-73
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• 2001

Until recently, we use only weekly and monthly adjustment factors in order to estimate the AADT. By the way. we can suppose that the traffic is time series data related to flow of time. So we tried to analyse traffic patterns using time series analysis and apply them to estimate the AADT. We could divide traffic patterns into trend, cyclic variation, seasonal variation and irregular variation like as time series data. Also, in order to reduce random error components, we have looked for the weather conditions as an influential factor. There are many weather conditions such as rainfalls, but, temperatures, and sunshine hours among others but we selected rainfalls and lowest temperatures. And then, we have estimated the AADT using time series factors. To compare the results of, we have applied both irregular variation joined to weather factors and that not joined to. RMSE and U-test were opted at methods to appreciate results of AADT estimation.

• Journal of Korea Trade
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• v.25 no.7
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• pp.1-18
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• 2021

Purpose - In this study, we explore the relationship between the degree of internationalization (DOI) and firm performance (DOI-P) of small and medium-sized enterprises (SMEs) in the manufacturing sector. Specifically, we investigate whether the costs and benefits dynamics concerning the internationalization of SMEs differ between high-tech and non-high-tech industries. Design/methodology - We extend the prior literature on this relationship by employing 5-year data on 589 Korean SMEs in the manufacturing sector and examining the moderating impact of the industry characteristics. Our findings reveal a U-shaped relationship between the DOI and SME performance. High-tech SMEs demonstrate an inverted U-shaped relationship, whereas non-hightech SMEs exhibit a U-shaped relationship. Findings - Our findings illustrate the importance of the industry factor in testing the performance impact of the internationalization of Korean SMEs. By incorporating industry dynamics, our results indicate that the DOI-P relationship depends on the context of the industry in which an SME operates. High-tech SMEs also display a higher DOI but are outperformed by non-high-tech SMEs for the entire internationalization path, which implies that high-tech SMEs face more challenges than non-high-tech SMEs while seeking internationalization. Originality/value - The findings strongly validate that significant benefits exist for SMEs undertaking internationalization. We also employ the contextual framework contributing to increasing the understanding of the intrinsic value of internationalization and resolving the mixed results issue on the DOI-P relationship, by illustrating that the industry factor leads to different dynamics of costs and benefits of SME internationalization; it also determines the shape and direction of the relationship.