• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.311-319
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• 2018

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (${\Delta}{\psi}_m$). Therefore, pharmacological manipulation of ${\Delta}{\psi}_m$ can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ${\Delta}{\psi}_m$ against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity ($100{\mu}M$, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate ($100{\mu}M$)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of $Ca^{2+}$ ($5{\mu}M$). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ${\Delta}{\psi}_m$ were completely abolished in $K^+-free$ medium on pure isolated mitochondria. Taken together, results demonstrate that $K^+$ influx into mitochondria is critically involved in partial mitochondrial depolarization-related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial $K^+$ influx is probably mediated, at least in part, by activation of mitochondrial $K^+$ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.691-696
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• 2000

Shear strengthening method by steel plates and fiber reinforced polymer lamination has recently been favorably selected due to its efficiencies of duration and performance. Shear failure being brittle and difficult to predict, reinforced concrete structures must have sufficient capacity to absorb the energy for shear failure and to support temporarily the overload which may result due to the loss of shear capacity to the structure. These respects being considered, this research has carried out with the purpose of the experimental verification of the shear strengthening effect and ductility evaluation.

• Journal of the Korea Safety Management & Science
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• v.16 no.1
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• pp.109-117
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• 2014

This paper reviewed the relationship between job demands/resources and safety participation, and the moderating effect of safety self-efficacy. Based on the responses from 247 employees, the results of multiple regression analysis appeared as follow; 1) job demands factors(role conflict, role ambiguity and role overload) effect negatively on safety participation. 2) job resources factors(autonomy and social support) effect positively on safety participation. 3) safety self-efficacy moderates positively 3 relationships-between role conflict and safety participation, between role ambiguity and safety participation, between social support and safety participation.

• Journal of Smart Tourism
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• v.3 no.3
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• pp.5-15
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• 2023

Given the increasing information overload among users of online review websites, understanding the manner in which cognitive costs are reduced and efficient information is made reliable has become increasingly important. This study targets a unique consumer review design and explores how reviews from an external peer-to-peer site embedded in an online travel agency (OTA) website influence subsequent evaluation behaviors. The empirical results indicate that (1) embedded external reviews with a high average valence tend to strengthen the influence of the positive evaluation ratio while diminishing the effect of the review volume, and (2) embedded external reviews with a large variance strengthen the positive effect of the review volume while weakening the effect of the positive evaluation ratio on subsequent positive evaluations. The findings provide practical insights for consumers and online platforms.

• Information Systems Review
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• v.16 no.2
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• pp.97-124
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• 2014

This study applies the concepts of sociotechnical theory and role theory in order to verify the effects of stress (that is, technostress) created from information and computer technology (ICT) concerning role stress and performance. We suggest diverse perspectives concerning the elements leading to technostress along with the stress-creating process of ICT among organizational members. The following four major hypotheses are proposed: (1) Technostress is positively related to role stress (e.g., conflict and overload of roles), adverse psychological outcomes, and adverse IS use related outcomes, (2) Role conflict is positively related to adverse psychological outcomes and adverse IS use related outcomes, (3) Role overload is positively related to adverse psychological outcomes and adverse IS use related outcomes, and (4) Innovation support will play as a moderator between technostress, roles tress, adverse psychological outcomes and adverse IS use related outcomes. A partial least square (PLS) with data gathered data from ICT users of organizations was used to verify the proposed hypotheses. The results supported our claims excluding the hypothesis associated to the relationship between technostress and role stress. We suggest a theoretical implication based on the verification of technostress related to the current concept of stress experienced by individuals within organizations. We also propose that a practical implication concerning the opposite effect of technostress, can be utilized as a method of reducing role stress, and suggests a diagnostic tool for assessing the degree of technostress within organizations.

• Journal of Ginseng Research
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• v.46 no.4
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• pp.515-525
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• 2022

Background: The incidence of ischemic cerebrovascular disease is increasing in recent years and has been one of the leading causes of neurological dysfunction and death. Ginsenoside Rg1 has been found to protect against neuronal damage in many neurodegenerative diseases. However, the effect and mechanism by which Rg1 protects against cerebral ischemia-reperfusion injury (CIRI) are not fully understood. Here, we report the neuroprotective effects of Rg1 treatment on CIRI and its possible mechanisms in mice. Methods: A bilateral common carotid artery ligation was used to establish a chronic CIRI model in mice. HT22 cells were treated with Rg1 after OGD/R to study its effect on [Ca²⁺]_i. The open-field test and poleclimbing experiment were used to detect behavioral injury. The laser speckle blood flowmeter was used to measure brain blood flow. The Nissl and H&E staining were used to examine the neuronal damage. The Western blotting was used to examine MAP2, PSD95, Tau, p-Tau, NOX2, PLC, p-PLC, CN, NFAT1, and NLRP1 expression. Calcium imaging was used to test the level of [Ca²⁺]_i. Results: Rg1 treatment significantly improved cerebral blood flow, locomotion, and limb coordination, reduced ROS production, increased MAP2 and PSD95 expression, and decreased p-Tau, NOX2, p-PLC, CN, NFAT1, and NLRP1 expression. Calcium imaging results showed that Rg1 could inhibit calcium overload and resist the imbalance of calcium homeostasis after OGD/R in HT22 cells. Conclusion: Rg1 plays a neuroprotective role in attenuating CIRI by inhibiting oxidative stress, calcium overload, and neuroinflammation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.04a
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• pp.34-34
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• 1997

The effect of alloying mode and porosity on the axial tension-tension fatigue behavior of a P/M steel of nominal composition Fe-4w/o Ni-1.5w/o Cu-O.5w/o Mo-O.5w/o C has been evaluated. Alloying modes utilized were elemental powder mixing, partial alloying(distaloy) and prealloying by water atomization; in each case the carbon was introduced as graphite prior to sintering. Powder compacts were sintered($1120{\circ}C$/30 min.) in 7Sv/o $H_2$/25v/o $N_2$ to densities in the range 6.77-7.2 g/$cm^3$. The dependence of fatigue limit response on alloying mode and porosity was interpreted in terms of the constituent phases and the pore and fracture morphologies associated with the three alloying modes. For the same nominal composition, the three alloying modes resulted in different sintered microstructures. In the elemental mix alloy and the distaloy, the major constituent was coarse and fine pearlite, with regions of Ni-rich ferrite, Ni-rich martensite and Ni-rich areas. In contrast, the prealloy consisted primarily of martensite by with some Ni-rich areas. From an examination of the fracture surfaces following fatigue testing it was concluded that essentially all of the fracture surfaces exhibited dimpled rupture, characteristic of tensile overload. Thus, the extent of growth of any fatigue cracks prior to overload was small. The stress amplitude for the three alloying modes at 2x$l0^6$ was used for the comparison of fatigue strengths. For load cycles <3x$l0^5$, the prealloy exhibited optimum fatigue response followed by the distaloy and elemental mix alloy, respectively. At load cycles >2x$l0^6$, similar fatigue limits were exhibited by the three alloys. It was concluded that fatigue cracks propagate primarily through pores, rather than through the constituent phases of the microstructure. A decrease in pore SIze improved the S-N behavior of the sintered steel.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.659-665
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• 2021

Short video applications (e.g., TikTok, YouTube shorts) are growing quickly in terms of active users and usage time. Of course, advertising industry is utilizing the app as AD channel. The current study, however, argues that the effectiveness of ADs in short video apps are not articulated well and that precise research for measuring the effect is required. In this context, this study measured the effects of storytelling ad types(reality, parody, creative) and message sensation value(high vs. low level) on story transportation. The notable finding is that when creative storytelling ad type which requires more cognitive resources than other two types meets high level of message sensation value, ad viewers could reach cognitive overload state which induced low effectiveness of ad. As its result, the effectiveness of AD reduced. More specific theoretical discussion and suggestions for advertising producers are described.

• Convergence Security Journal
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• v.15 no.3_2
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• pp.31-42
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• 2015

This study aims to discuss how job stress of private security guards would influence organizational commitment and turnover intention, and it basically looks into mediating effects of job burnout to understand the former's effects on the latter. In order to conduct the analysis, the study selected private security guards working for security agencies located in Seoul as a research subject, and carried out a survey targeting 700 of those security guards who had been gathered by a random cluster sampling method. The survey was conducted for about four months from May of 2014 to September of the same year and with 24 samples that had not been returned or that had been observed to have some outliers excluded, a total of 676 samples were applied as final data. The study used SPSSWIN 18.0 Statistical Package for analyzing the data, and hypotheses were confirmed via a Frequency Analysis, Factor analysis, Cronbach's Alpha, Person's Correlation Analysis, regression analysis and a path analysis. Findings of the analysis reported that emotional exhaustion has partially mediating effects on relations among role conflict, role overload and organizational commitment and that role ambiguity is not significantly connected. In addition, as for a relation of role conflict and turnover intention, emotional exhaustion was turned out to have a full mediating effect on the relation. The study did not notice any significant connection between emotional exhaustion and role ambiguity. Add to that, in terms of a relation between role overload and turnover intention, emotional exhaustion appeared to have a partial mediating effect on the relation which helped a relevant hypothesis to be partly adopted. Regarding a relation of job stress with organizational commitment, according to results of a path analysis on dehumanization, dehumanization does not significantly affect a relation between role ambiguity and organizational commitment and as for role conflict and role overload, the study confirmed that they have a partially mediating effect on this relation of dehumanization with organizational commitment. The study learned then that dehumanization does not have a significant influence on a relation between role ambiguity and turnover intention. However, the study figured out that when it comes to a relation of role conflict and role overload, dehumanization has a partially mediating effect on the relation and as a consequence, a relevant hypothesis was adopted in part.

• Asia Marketing Journal
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• v.13 no.1
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• pp.113-141
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• 2011

Companies are competing each other, and as the competitions became higher, consumer's information processing for purchase became more complicated. Consumer confusion problem is getting more serious, but there are still not much considerations on this problem. The purpose of this study is to find out that the consumer confusion can causes consumer's negative emotion(anger). This research studied the mediation effect of negative emotion on the relationship between consumer confusion, which was classified into three categories, and two consequences, word-of-mouth and trust. And also it concentrates on moderating effects of negative affectivity and intolerance of uncertainty in the relationship between consumer confusion and negative emotion. For the empirical study, we carried out a survey targeting consumers who live in the Dae-gu metropolitan area. The specific results of this study are as follows. First, all sub-dimensions of the consumer confusion had a positive effect on anger. Second, anger had a positive effect on word of mouth and on the other hand, anger had a negative effect on trust. Third, negative affectivity had a moderating effects on the links between overload and ambiguity confusion with anger, and intolerance of uncertainty only had a moderating effects on the links between overload confusion and anger.