• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.603-610
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• 2020

This study examined the mental health-related factors of Korean adolescents, especially focusing on the influence of internet use. This study analyzed the raw data from the 14th Korea Youth Risk Behavior Survey, 2018. The study population was 60,040, with 50.7% male students and 49.3% female students, and 49.7% high school students and 50.3% middle school students. The dependent variables were stress, sadness and despair, suicidal ideation, suicidal plan, and suicidal attempt. The independent variables were gender and age, health behaviors, and time using the internet. Logistic regression analysis was applied to derive the related factors. For all dependent variables, the main contributing variables were gender, grade, economic status, and academic performance. The mental health of adolescents was related to various factors. In particular, the time using the internet was linearly related to the degree of stress, and a higher student group of time using the internet had a more significant effect on sadness, despair, suicidal thoughts, and suicidal plans. In conclusion, the time using the internet has harmful effects on the mental health of Korean adolescents.

• Journal of Physiology & Pathology in Korean Medicine
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• v.31 no.4
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• pp.220-225
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• 2017

Lithospermi Radix (LR) is known to have an anti-inflammatory effect. However, the mechanisms are not well known. In this study, LPS-induced mouse RAW 264.7 macrophage cells were treated with LR to investigate the time-dependent inflammation response of LR. RAW 264.7 cells were treated with various concentrations of LR for 24 hours, followed by MTS assay. Cell viability was increased at all experimental concentrations. The mRNA expression levels of $IL-1{\beta}$, $TNF-{\alpha}$ and iNOS were increased by treatment of RAW 264.7 cells with LR at a concentration of $200{\mu}g/ml$ for 6 hours and 24 hours. Treatment of LR with $200{\mu}g/ml$ concentration for 6 hours promoted mRNA expression levels of $IL-1{\beta}$, $TNF-{\alpha}$ and iNOS in LPS-induced RAW 264.7 cells. However, $IL-1{\beta}$, $TNF-{\alpha}$ and iNOS mRNA expression was suppressed by treatment of LR with $200{\mu}g/ml$ concentration for 24 hours in LPS-induced RAW 264.7 cells. These results suggest that the effect on inflammation of LR is promptly promoted and then to rapidly alleviate the inflammatory reaction. This study proposes that the time-dependent activities of herbal medicine is a very important factor in analyzing the anti-inflammatory effect of various herbal medicines including LR.

• Natural Product Sciences
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• v.29 no.1
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• pp.42-49
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• 2023

This study investigated the effect of ethanol extracts of horsetail, alfalfa, ortie, chêne and aleppo oak on blood coagulation in vitro. Extraction was performed by the maceration method. Extracts were mixed with platelet and plasma, then prothrombin time (PT), activated partial thromboplastin time (APTT) and platelet aggregation tests were conducted. Alfalfa extract had a dose-dependent effect on the PT. Ortie, and horsetail, reduced the PT significantly compared to control group. Alfalfa, horsetail, and ortie reduced the APTT, but their effect was insignificant compared to the control group. The pooled extract showed the highest effect compared to the single extracts in a dose-dependent manner. Horsetail and alfalfa induced platelet aggregation in response to arachidonic acid but not in response to collagen. In the case of ortie, no aggregation occurred regarding the arachidonic acid, and incomplete was observed in response to collagen. Interestingly, blood clotting occurred immediately after adding the chêne, aleppo oak and the pooled extract, and therefore platelet poor plasma (PPP) and platelet rich plasma (PRP) became jelly. Generally, chêne and aleppo oak, as well as pooled extract, were more effective in inducing both primary and secondary coagulation pathways via shortening the PT and APTT, and induction of platelet aggregation.

• The Journal of Korean Medicine
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• v.24 no.2
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• pp.166-178
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• 2003

Objectives : Nitric oxide (NO) plays an important role in normal and pathophysiological cells as a messenger molecule, neurotransmitter, microbiological agent, or dilator of blood vessels and arteriosclerosis, respectively. This study was undertaken to understand the mechanism of NO production and effect of Hyeolbuchukeo-tang (Xiefuzhuyu-tang) on NO production in cultured vascular smooth muscle cell (VSMC). Methods and Results : VSMC was isolated from aorta and cultured. Cultured primary cells were identified as VSMC with anti--smooth muscle actin antibody. A large amount of NO was produced in cultured VSMC treated with $IFN-{\gamma}$ plus TNF in a time- and dose-dependent manner. $TNF-{\alpha}$ was a more efficient stimulator than $IFN-{\gamma}$ in NO production of cultured VSMC. iNOS protein wasdetected within 3 hrs and it increased up to 12 hrs in a time-dependent manner. However, accumulated NO in cytokine-treated VSMC was not detected within 3 hrs. NO production in cytokine-treated VSMC showed the dose- and time-dependent manner, and increased up to 48 hrs. The activated VSMC produced a large amount of NO (about 60 uM). Hyeolbuchukeo-tang (Xiefuzhuyu-tang) alone did not induceNO production, but it potentiated the effect of $TNF-{\alpha}$ on NO production and increased NO production by about 20%. Hyeolbuchukeo-tang (Xiefuzhuyu-tang) did not affect the transcriptional activity of iNOS gene, but increased the accumulation of iNOS. These results indicate that Hyeolbuchukeo-tang (Xiefuzhuyu-tang) could modulate the translational level of iNOS. PKC did not modulate NO production, but calcium ionophore A23187 decreased NO production. However, Hyeolbuchukeo-tang (Xiefuzhuyu-tang) elevated the decreased NO production in A23187-treated VSMC by modulating the stability of iNOS transcripts. Half-life of the synthesized transcripts appeared to have about 6 hrs. PDTC, an $NF-{\kappa}B$ inhibitor, blocked the accumulation of iNOS mRNA, indicating that $NF-{\kappa}B$ served as an important modulator in the transcriptional regulation of iNOS. As Hyeolbuchukeo-tang (Xiefuzhuyu-tang) potentiated the effect of the $TNF-{\alpha}$ on NO production but had no additional effect on PDTC-modulated NO production, it is suggested that Hyeolbuchukeo-tang (Xiefuzhuyu-tang) enhances the $TNF-{\alpha}-mediated$ NO production of VSMC by modulating the iNOS activity and the stability of iNOS transcripts in activated VSMC having the elevated intracellular calcium ion. Conclusions : This study suggests that Hyeolbuchukeo-tang (Xiefuzhuyu-tang) has a potential capacity for preventing and treating diseases of the circulation system, including arteriosclerosis.

• Journal of Korean Academy of Nursing
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• v.34 no.6
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• pp.934-944
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• 2004

Purpose: This meta-analysis was conducted to evaluate the effects of a self-efficacy promoting program and analyze its components. Method: The material used for this study were 18 self-efficacy promoting program studies carried out from Jan. 1980 to Oct. 2003. The studies were analyzed in differen categories: 1) types of dependent variables 2) sample characteristics 3) types of experimental treatment conditions 4) types of self-efficacy source and 5) total amount of time Result: 1) The weighted mean of a self-efficacy promoting program ranged from 1.383 to 0.015 2) for the experimental treatment condition, exercise had a much larger effect in increasing general self-efficacy and self-care than education 3) the studies using 3 sources had a much larger effect in increasing self-care than the studies using 4 sources 4) a time period longer than 900 minutes had a much larger effect in increasing specific self-efficacy, general self-efficacy and self-care than in a time period shorter than 900 minutes. 5) effect size of specific self-efficacy was significantly higher than general self-efficacy. Conclusion: These results can be used to guide the development of a self-efficacy promoting program for nursing practice.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.4
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• pp.467-481
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• 2013

The study examined the main effect of the reward channel and reward time of customer loyalty programs for on-offline shopping channels; in addition, it investigated the interaction effect of the reward channels and merchandise as well as the interaction effect of the reward time and merchandise. An online apparel shopping web experiment was conducted with a 2 (reward channel: online channel reward vs. offline channel reward) ${\times}2$ (reward time: immediate vs. delayed) ${\times}2$ (merchandise: online channel product vs. offline channel products) between-subject factorial design. An online shopping channel was considered the core-shopping channel and a department store was considered the cross-shopping channel. Loyalty program value, core-channel loyalty and cross-channel loyalty were measured as dependent variables. A total of 845 shoppers (who had experiences in shopping in both channels) participated in the experiment. The results of the study revealed (1) the main effect of the reward channel on loyalty program value, core-channel loyalty and cross-channel loyalty [online>offline channel rewards], (2) the main effect of reward time on loyalty program value, core-channel loyalty and cross-channel loyalty [immediate>delayed reward], and (3) the interaction effect of the reward channel and merchandise on loyalty program value, core-channel loyalty, and cross-channel loyalty. (4) Finally the study found that loyalty program value affected cross-channel loyalty indirectly through core-channel loyalty. This study suggested diverse theoretical and managerial implications for multi-channel retailers.

• Molecules and Cells
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• v.28 no.3
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• pp.189-194
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• 2009

The modulating effect of IGF-I on the regulation of AR gene expression and activation in skeletal muscle cells remains poorly understood. In this study, the effects of IGF-I treatment on AR induction and activation in the absence of AR ligands were examined. Differentiating C2C12 cells were treated with different concentrations (0-250 ng/ml) of IGF-I or for various periods of time (0-60 min) of 250 ng/ml IGF-I. Treatment of C2C12 cells with IGF-I resulted in a dose- and time-dependent increase in total AR and phosphorylated AR (Ser 213). IGF-I treatment also led to significantly increased AR mRNA expression when compared with the control. The levels of skeletal ${\alpha}-actin$ and myogenin mRNA, known target genes of AR, were also significantly upregulated after 5 or 10 min of treatment with IGF-I. Confocal images revealed that IGF-I stimulated nuclear localization of AR in the absence of ligands. In addition, an electrophoretic mobility shift assay indicated that IGF-I stimulated the AR DNA binding activity in a time-dependent manner. The present results suggest that IGF-I stimulates the expression and activation of AR by ligand-independent mechanism in differentiating C2C12 mouse skeletal muscle cells.

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.78-86
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• 1992

The creep behaviors of 1%Cr-Mo-V and 12%Cr steam turbine rotor steels under static or cyclic load were examined at 600 and $700^{\circ}C$. The relationship between these two kinds of phenomena was studied and the experimental results were summarized as follows: 1) It is confirmed that the cyclic creep strain dependent on time is more available for creep, behavior analysis according to frequency change than that dependent on number of cycles, and the static creep, the special case of cyclic creep with stress ratio of 1 can be also more effectively analyzed by time-dependence. 2) The steady cyclic creep rate vs. the steady static creep rate, increases according to the increase of stress ratio, and this phenomena may occur on occasion of the decrease of the internal stress. 3) The initial strain affects on all the creep properties of the transient region, the steady state region and the rupture time in cyclic creep as well as static creep, and the quantitative relationships among them exist.

• Advances in environmental research
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• v.4 no.2
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• pp.119-133
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• 2015

Water pollution means that the physical, chemical and biological properties of water are changing. In this study, adsorption was chosen as the treatment method because it is an eco-friendly and low cost approach. Magnetite is a magnetic material that can synthesize chemical precipitation. Magnetite was used for the removal of copper in artificial water samples. For this purpose, metal removal from water dependent on the pH, initial concentration of metal, amount of adsorbent and effect of sorption time were investigated. Magnetite was characterized using XRD, SEM and particle size distribution. The copper ions were determined by atomic absorption spectrometry. The adsorption of copper on the magnetite was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 10 to $50mg\;l^{-1}$. Optimum conditions for using magnetite were found to be concentration of $10mg\;L^{-1}$, pH: 4.5, contact time: 40 min. Optimum adsorbent was found to be 0.3 gr. Furthermore, adsorption isotherm data were analyzed using the Langmuir and Freundlich equations. The adsorption data fitted well with the Freundlich ($r^2=0.9701$) and Langmuir isotherm ($r^2=0.9711$) equations. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were described well by a pseudo-second-order kinetic model.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.725-737
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• 2017

An analytical method considering axial equilibrium is proposed for the short- and long-term analyses of shear lag effect in reinforced concrete (RC) box girders. The axial equilibrium of box girders is taken into account by using an additional generalized displacement, referred to as the longitudinal displacement of the web. Three independent shear lag functions are introduced to describe different shear lag intensities of the top, bottom, and cantilever plates. The time-dependent material properties of the concrete are simulated by the age-adjusted effective modulus method (AEMM), while the reinforcement is assumed to behave in a linear-elastic fashion. The differential equations are derived based on the longitudinal displacement of the web, the vertical displacement of the cross section, and the shear lag functions of the flanges. The time-dependent expressions of the generalized displacements are then deduced for box girders subjected to uniformly distributed loads. The accuracy of the proposed method is validated against the finite element results regarding the short- and long-term responses of a simply-supported RC box girder. Furthermore, creep analyses considering and neglecting shrinkage are performed to quantify the time effects on the long-term behavior of a continuous RC box girder. The results show that the proposed method can well evaluate both the short- and long-term behavior of box girders, and that concrete shrinkage has a considerable impact on the concrete stresses and internal forces, while concrete creep can remarkably affect the long-term deflections.