• YAKHAK HOEJI
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• v.32 no.2
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• pp.129-136
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• 1988

Effects of the selective alpha-adrenoceptor agonists, clonidine, oxymetazoline and phenylephrine, on heart rate and contractile force were investigated in the isolated frog atria and it was attempted to examine the influence of adrenoceptor antagonist upon those. Clonidine produced dose-dependent negative chronotropic and positive inotropic effects. The negative chronotropic effect was significantly attenuated in the presence of prazosin and yohimbine but not propranolol. The positive inotropic effect was significantly attenuated by prazosin, yohimbine and propranolol. Oxymetazoline produced dose-dependent negative chronotropic and inotropic effects. The negative chronotropic effect was significantly attenuated in the presence of prazosin, which was partially augmented by yohimbine but was not affected by propranolol. The negative inotropic effect was not affected by propranolol but it was partially augmented by yohimbine and was partially attenuated by prazosin. Phenylephrine produced dose-dependent positive chronotropic and inotropic effects. The positive chronotropic and inotropic effect were significantly attenuated in the presence of propranolol but were not affected by prazosin and yohimbine. These results suggest that the negative chronotropic effect by clonidine and oxymetazoline is mediated by alpha-adrenoceptors, the positive chronotropic and inotropic effects by phenylephrine are mediated by beta-adrenoceptors, and alpha-adrenoceptors mediated the inhibitory chronotropic responses exists in the isolated frog atria.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.51-66
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• 2007

A layer of compressible, rotating, elastica-viscous fluid heated & soluted from below is considered in the presence of vertical magnetic field to include the effect of Hall currents. Dispersion relation governing the effect of viscoelasticity, salinity gradient, rotation, magnetic field and Hall currents is derived. For the case of stationary convection, the Rivlin-Erickson fluid behaves like an ordinary Newtonian fluid. The compressibility, stable solute gradient, rotation and magnetic field postpone the onset of thermosolutal instability whereas Hall currents are found to hasten the onset of thermosolutal instability in the absence of rotation. In the presence of rotation, Hall currents postpone/hasten the onset of instability depending upon the value of wavenumbers. Again, the dispersion relation is analyzed numerically & the results depicted graphically. The stable solute gradient and magnetic field (and corresponding Hall currents) introduce oscillatory modes in the system which were non-existent in their absence. The case of overstability is discussed & sufficient conditions for non-existence of overstability are derived.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.179-182
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• 2000

Toluene-degrading bacterium, Microbacterium esteraromaticum CS3-1 was isolated from the biofilter for the removal of BTEX. Microbacterium esteraromaticum CS3-1 was shown to utilize toluene as a primary carbon and energy source. Effect of mixed BTEX gases on toluene degradation rate by M. esteraromaticum CS3-1 was investigated in this study. Toluene degradation rate was 2.26(only toluene), 2.06(toluene+benzene), 2.57(toluene+ethylbenzene), and 4.74(toluene+xylene) mmole $toluene\;{\cdot}\;g-DCW^{-1}\;{\cdot}\;h^{-1}$. Toluene degradation rate was 2.26(only toluene), 1.23(toluene+benzene+ethylbenzene), 1.52 (toluene+ethylbenzene+xylene), and 1.76(toluene+benzene+ethylbenzene+xylene) mmole $toluene\;{\cdot}\;g-DCW^{-1}\;{\cdot}\;h^{-1}$. The presence of BTEX compounds over three mixtures had a negative effect on toluene degradation rate. Toluene degradation rates were enhanced by the presence of ethylbenzene or xylene, whereas the presence of benzene had a negative effect on toluene degradation rate in comparison with toluene degradation rate when only toluene is existent.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4239-4243
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• 2011

Biocompatible hydrogels from 2-hydroxyethyl methacrylate (HEMA) monomer containing various amount of alginate in the presence and absence of hydrophilic methacrylic acid (MAA) were synthesized in order for biomedical application. The antimicrobial effect and interaction with proteins for hydrogels were investigated in this study. MAA was introduced because it was expected to increase the amount of water content in the polymer which is an important factor for biocompatibility, and alginate was expected to enhance the antimicrobial activity. The antimicrobial effect against S. aureus and E. coli increased for all hydrogels as the amount of alginate and MAA contained. Presence of MAA further enhances the antimicrobial effect. Amount of adsorption of bovine serum albumin (BSA) increased with increasing concentration of alginate whether MAA was present or not. Contrarily, the amount of lysozyme was not affected with increasing alginate concentration in the absence of MAA, while it decreased in the presence of MAA.

• The Journal of Korean Association of Computer Education
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• v.16 no.4
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• pp.1-11
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• 2013

The purpose of this study is to investigate a structural relationship among elementary students' self-determinant learning motivation, teaching-presence and learning outcomes (learning satisfaction, persistence) in blended learning environment. Participants were 5th and 6th grade students who enrolled in a mathematics learning service. The results showed that self-determinant learning motivation had direct effect on teaching presence, learning satisfaction and learning persistence. Teaching Presence had an direct effect on learning satisfaction and learning satisfaction had an direct effect on learning persistence. Based on the results, proper strategies were recommended to facilitate self-determinant learning motivation and teaching presence before and during learning since they play critical roles for the success of elementary students learning outcomes in a blended learning environment.

• Journal of Broadcast Engineering
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• v.26 no.5
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• pp.508-518
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• 2021

Recently as a result of covid 19, it has emphasis on the importance of non-contact. VR content has been attracting attention as an alternative to visual arts, media art, new media exhibitions and performances with limited offline activities. Although interest in 360 VR video contents such as VR contents for exhibitions and performances is increasing, research on immersion and satisfaction is focused on games and animation VR contents. In this paper, it verified the effect of the difference in the position and height of the VR camera in exhibitions and performances on the user's presence and satisfaction. For this experiment, the presence and satisfaction were measured after experiencing the VR contents of the convergence exhibition and performance filmed at different locations and heights. As a result of the experiment, the difference of VR camera's position had a significant effect on presence and satisfaction, the difference of VR camera's height had a significant effect only Realistic immersion of the presence.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.223-237
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• 2022

The purpose of this study is to examine the influence of the presence and transportation of the experience of seeing a musical upon satisfaction and verify the mediating effect of emotional responses. For this study, the researcher surveyed the audiences of a musical and analyzed the response from 339 participants. The data were analyzed using SPSS 23.0 and AMOS 23.0 programs. The findings of this study are as follows; First, the presence and transportation of the experience of seeing a musical had a significant impact on emotional responses. Second, the presence and transportation in the experience of seeing a musical had a significant impact on satisfaction. Third, the emotional responses to the musical had a significant impact on satisfaction. Fourth, emotional responses were shown to have a mediating effect in the relationship between the presence and transportation of the experience and the satisfaction with it. As the share of online performances in performing art industries is increasing and the paradigm of seeing a performance is changing, this study implies that it provided a set of basic data for the industry and producers of such events, who are now seeking a new profit model through not only in-person events but also online performances in the future.

• Journal of the Ergonomics Society of Korea
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• v.27 no.2
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• pp.39-47
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• 2008

This research was conducted to explore relationships among situation awareness, presence, and performance on a handheld game console. Situation Awareness was measured by SAGAT (Situation Awareness Global Assessment Technique) while presence was measured by PQ (Presence Questionnaire) version 3.0. The performance was measured by the number of aircraft shot down during the flight simulator game. The results show that both situation awareness and presence were positively significantly correlated with performance. In order to investigate the effect of performance level, subjects were divided into two significantly different groups: low and high performance groups. In the low performance group, both situation awareness and presence showed a significantly positive correlation with performance. The correlation between presence and situation awareness also showed a positively significant correlation. However, in the high performance group, there were no significant correlations among them. In conclusion, different performance levels could be said to be an important factor in the study of situation awareness and presence. Furthermore, this study also proved that the domain of research on situation awareness and presence was extended to small displays such as the handheld game console.

• YAKHAK HOEJI
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• v.53 no.5
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• pp.259-264
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• 2009

The present study was to investigate the effect of naringin, a flavonoid, on the pharmacokinetics of losartan in rats. Pharmacokinetic parameters of losartan in rats were determined after an oral administration of losartan (9 mg/kg) in the presence or absence of naringin (0.5, 2.5 and 10 mg/kg). The pharmacokinetic parameters of losartan were significantly altered by the presence of naringin compared with the control group (given losartan alone). Presence of naringin significantly (p<0.05, 2.5 mg/kg; p<0.01, 10 mg/kg) increased the area under the plasma concentration?time curve (AUC) of losartan by 43.7~63.0% and peak plasma concentration ($C_{max}$) of losartan by 31.7~45.5%. Consequently, the absolute bioavailability (AB) of losartan in the presence of naringin was 43.8~62.9%, which was enhanced significantly (p<0.05, p<0.01) compared to that in the oral control group (22.4%). The relative bioavailability (R.B.) of losartan increased by 1.44- to 1.63-fold in the presence of naringin. However, there was no significant change in the peak plasma concentration ($T_{max}$) and terminal half-life ($t_{1/2}$) of losartan in the presence of naringin. In conclusion, the presence of naringin significantly enhanced the oral bioavailability of losartan, implying that presence of naringin might be mainly effective to inhibit the cytochrome P450 (CYP)3A-mediated metabolism, resulting in reducing gastrointestinal and hepatic first-pass metabilism and Pglycoprotein (P-gp)-mediated efflux of losartan in small intestine. Concurrent use of naringin or naringin-containing dietary supplement with losartan should require close monitoring for potential drug interactions.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.2
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• pp.295-310
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• 2023

The current virtual fashion influencers are a hyper-real prototype in that it has a higher presence than the virtual humans in the past. Also, they are leading fashion trend with more than tens of thousands of followers on social media. This study investigated the physical and social presence of virtual fashion influencer perceived by consumer and verified effects on evaluation attributes of influencers and the relationship maintenance behavior. A total of 321 Korean women in their 20s and 30s who have Instagram account participated in the online survey. The data was analyzed using AMOS 23.0. The results revealed that the physical presence had a significant impact on attractiveness of virtual fashion influencers. In case of social presence had a positive effect on friendliness and reliability of virtual fashion influencers. In addition, evaluation attributes of virtual fashion influencers' friendliness, attractiveness and reliability in the order of influence on relationship maintenance behavior. This study suggested that the development of social presence of virtual fashion influencers with friendliness and attractiveness is more important than the physical presence that has already reached a high level.