• Journal of Electrochemical Science and Technology
• /
• v.12 no.2
• /
• pp.230-236
• /
• 2021

Ionic conduction mechanism of Mg-Al layered double hydroxides (LDHs) intercalated with CO₃^2- (Mg-Al CO₃^2- LDH) was studied. The electromotive force for the water vapor concentration cell using Mg-Al CO₃^2- LDH as electrolyte showed water vapor partial pressure dependence and obeyed the Nernst equation, indicating that the hydroxide ion transport number of Mg-Al CO₃^2- LDH is almost unity. The ionic conductivity of Mg(OH)₂, MgCO₃ and Al₂(CO₃)₃ was also examined. Only Al₂(CO₃)₃ showed high hydroxide ion conductivity of the order of 10^-4 S cm^-1 under 80% relative humidity, suggesting that Al₂(CO₃)₃ is an ion conducting material and related to the generation of carrier by interaction with water. To discuss the ionic conduction mechanism, Mg-Al CO₃^2- LDH having deuterium water as interlayer water (Mg-Al CO₃^2- LDH(D₂O)) was prepared. After the adsorbed water molecules on the surface of Mg-Al CO₃^2- LDH(D₂O) were removed by drying, DC polarization test for dried Mg-Al CO₃^2- LDH(D₂O) was examined. The absorbance attributed to O-D-stretching band for Mg-Al CO₃^2- LDH(D₂O) powder at around the positively charged electrode is larger than that before polarization, indicating that the interlayer in Mg-Al CO₃^2- LDH is a hydroxide ion conduction channel.

• The Journal of Advanced Prosthodontics
• /
• v.11 no.3
• /
• pp.162-168
• /
• 2019

PURPOSE. The aim of this study was to evaluate the effect of occlusal adjustments on the surface roughness of yttria-tetragonal zirconia polycrystal (Y-TZP) and wear of opposing artificial enamel. MATERIALS AND METHODS. Twenty-five Y-TZP slabs from each brand (Lava, 3M and Bruxzir, Glidewell Laboratories) with different surface conditions (Control polished - CPZ; Polished/ground - GRZ; Polished/ground/repolished - RPZ; Glazed - GZ; Porcelain-veneered - PVZ; n=5) were abraded (500,000 cycles, 80 N) against artificial enamel (6 mm diameter steatite). Y-TZP roughness (in ${\mu}m$) before and after chewing simulation (CS) and antagonist steatite volume loss (in $mm^3$) were evaluated using a contact surface profilometer. Y-TZP roughness was analyzed by three-way analysis of variance (ANOVA) and steatite wear by two-way ANOVA and Tukey Honest Difference (HSD) (P=.05). RESULTS. There was no effect of Y-TZP brand on surface roughness (P=.216) and steatite loss (P=.064). A significant interaction effect (P<.001) between surface condition and CS on Y-TZP roughness was observed. GZ specimens showed higher roughness after CS (before CS - $3.7{\pm}1.8{\mu}m$; after CS - $13.54{\pm}3.11{\mu}m$), with partial removal of the glaze layer. Indenters abraded against CPZ ($0.09{\pm}0.03mm^3$) were worn more than those abraded against PVZ ($0.02{\pm}0.01mm^3$) and GZ ($0.02{\pm}0.01mm^3$). Higher wear caused by direct abrasion against zirconia was confirmed by SEM. CONCLUSION. Polishing with an intraoral polishing system did not reduce the roughness of zirconia. Wear of the opposing artificial enamel was affected by the material on the surface rather than the finishing technique applied, indicating that polished zirconia is more deleterious to artificial enamel than are glazed and porcelain-veneered restorations.

• Membrane Journal
• /
• v.28 no.6
• /
• pp.388-394
• /
• 2018

Carbon nanotube (CNT) based membranes are promising candidates for separation membranes by showing high water transport rate and ion rejection rate according to their radii. The ion selectivity is an important factor to discover the full potential of CNT membranes, and it is affected by the functionalization of CNTs. With multivalent/size ion mixtures, the ion selectivity is affected by not only ion-functional groups interaction but also ion-ion interactions and ion size exclusion in a complex manner. In this study, molecular dynamics simulations are performed to study the ion selectivity of functionalized carbon nanotubes when multivalent/size ions are contained. The permeation energy barriers are calculated by plotting potential of mean force profiles, and various factors, such as CNT size and partial charges, affecting ion selectivity are investigated. The results presented here will be useful for designing CNT membranes for ion separation, biomimetic ion channels, etc.

• Journal of Digital Convergence
• /
• v.17 no.4
• /
• pp.267-278
• /
• 2019

The purpose of this study is to verify empirically the effects of BJ worship and perceived homophily on game efficacy through mediating effect of loyalty to viewing. 485 participants who had watched personal game broadcasting were collected as a sample through an online survey and the collected data were analyzed through structural equation modeling. The research model assuming full mediating effect and the alternative model assuming partial mediating effect were compared and bootstrapping was performed to analyze direct and indirect effects between variables. The results showed BJ worship and perceived homophily had significant effects on game efficacy through the full mediated effect of loyalty to viewing. The noteworthy contribution of this study is to verify how viewing personal game broadcasting has a significant impact on the formation of game efficacy and then ultimately provide positive perception of BJ.

• Geomechanics and Engineering
• /
• v.24 no.1
• /
• pp.29-42
• /
• 2021

The utilization of buildings can be improved by extending them vertically. However, the added load of the extension might require building foundations to be underpinned; otherwise, the loads on the foundations might exceed their bearing capacity. In this study, a preloading method was presented aiming at transferring partial loads from existing piles to underpinning piles. A pneumatic-type model preloading device was developed and used to carry out centrifuge experiments to evaluate the load-displacement behavior of piles, the pile-soil interaction during preloading, and the additional loading caused by vertical extension. The results showed that the preloading devices effectively transfer load from existing piles to underpinning piles. In the additional loading test of group piles, the load-sharing ratio of a pile increased with its stiffness. The load-sharing ratio of a preloaded micropile was less than that of a non-preloaded micropile as a result of the reduction in axial stiffness caused by preloading before additional loading. Therefore, a slight reduction of the load-sharing capacity of an underpinning pile should be considered if the preloading method is applied. Further, two full scale preloading devices was developed. The devices preload underpinning piles and thereby produce reaction forces on a reaction frame to jack existing piles upward, thus transferring load from the existing piles to the underpinning piles. Specifically, screw-type and hydraulic-jack type devices were developed for the practical application of foundation underpinning during vertical extension, and their operability and load transfer effect verified via full-scale structural experiments.

• International Area Studies Review
• /
• v.21 no.1
• /
• pp.79-96
• /
• 2017

As Chinese luxury consumption is rapidly expanding and dominant in global luxury market, it becomes very critical to understand Chinese consumers' luxury consumption pattern. Under this circumstance, this study empirically tested the impacts of Chinese consumers' perceived service quality of luxury stores and extended self of luxury on luxury purchasing intention. The result of this study is as follows. First of all, Chinese consumer' perceived service quality of luxury store and extended self of luxury have positive impacts on luxury purchasing intention. However, Chinese consumer' extended self of luxury has partial interaction impact on luxury purchasing intention. From the results, to promote Chinese consumers' luxury consumption, marketers must improve the service quality of luxury store and extended self of luxury. This research not only enrich theoretical knowledge about Chinese consumers' luxury purchase behavior, but also assist marketer to develop luxury marketing strategies in China.

• Advances in nano research
• /
• v.11 no.6
• /
• pp.581-593
• /
• 2021

This model is proposed to describe the buckling behavior of Carbon Nanotubes (CNTs) embedded in an elastic medium taking into account the combined effects of the magnetic field, the temperature, the nonlocal parameter, the number of walls. Using Eringen's nonlocal elasticity theory, thin cylindrical shell theory and Van der Waal force (VdW) interactions, we develop a system of partial differential equations governing the buckling response of CNTs embedded on Winkler, Pasternak, and Kerr foundations in a thermal-magnetic environment. The pre-buckling stresses are obtained by applying airy's stress function and an adjacent equilibrium criterion. To estimate the nonlocal critical buckling load of CNTs under the simultaneous effects of the magnetic field, the temperature change, and the number of walls, an optimization technique is proposed. Furthermore, analytical formulas are developed to obtain the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effects of the nonlocal parameter. These formulas take into account VdW interactions between adjacent tubes and the effect of terms involving differences in tube radii generally neglected in the derived expressions of the critical buckling load published in the literature. Most scientific research on modeling the effects of magnetic fields is based on beam theories, this motivation pushes me to develop a cylindrical shell model for studying the effect of the magnetic field on the static behavior of CNTs. The results show that the magnetic field has significant effects on the static behavior of CNTs and can lead to slow buckling. On the other hand, thermal effects reduce the critical buckling load. The findings in this work can help us design of CNTs for various applications (e.g. structural, electrical, mechanical and biological applications) in a thermal and magnetic environment.

• Journal of Digital Convergence
• /
• v.20 no.5
• /
• pp.221-226
• /
• 2022

The purpose of this study is to explore the differentiated motivations of users of live commerce by focusing on the entry into untact consumption culture. In addition, we intend to verify the mediating effect of engagement in the relationship between the motivation and attitude of live commerce use. As for the research method, an online survey was conducted targeting live commerce users, and 245 valid samples were used for analysis. For data analysis, frequency analysis, exploratory factor analysis, reliability analysis, multiple regression analysis, and mediation regression analysis were performed. As a result of the analysis, the motivation for using live commerce was derived from four factors: Enjoyment of interaction, Substitutability of personal examination, Need for community, Trend setting. And Engagement was found to have a significant effect on attitude. Finally, engagement was found to have a partial mediating effect in the relationship between the motivation and attitude of live commerce use. The research results will provide implications for understanding non-face-to-face consumption culture and establishing effective strategies for the live commerce industry in the future.

• Korean Journal of Culture and Social Issue
• /
• v.27 no.4
• /
• pp.505-528
• /
• 2021

The current study examined the differential effects of giving and receiving social support in the elderly when relationships(family, friend/neighbor) are important. For this purpose, the mediation effects of meaning in life on the relationship between giving and receiving social support and self-esteem were analyzed. Self-reporting data of 310 adults aged over 60 living in Busan and Gyeongnam in South Korea were collected regarding giving and receiving social support, meaning of life and self-esteem. The mediation analysis showed that giving social support had a positive effect on self-esteem with the partial mediation effect of meaning in life. Receiving social support, however, showed no significant mediation effect of meaning in life. This pattern was similar regardless of both family and non-family relations. The result that giving social support enhances self-worth in the elderly through meaning in life suggests the importance of social interaction with intimate others as a source of happiness in the elderly.

• Journal of Electrochemical Science and Technology
• /
• v.14 no.1
• /
• pp.96-104
• /
• 2023

Synergistically increased oxygen evolution reaction (OER) of manganese oxide (MnO₂) catalyst is introduced with surface-modified halloysite nanotube (Fe₃O₄-HNTs) structure. The flake shaped MnO₂ catalyst is attached on the nanotube template (Fe₃O₄-HNTs) by series of wet chemical and hydrothermal method. The strong interaction between MnO₂ and Fe₃O₄-HNTs maximized active surface area and inter-connectivity for festinate charge transfer reaction for OER. The synergistical effect between Fe₃O₄ layer and MnO₂ catalyst enhance the Mn³⁺/Mn⁴⁺ ratio by partial replacement of Mn ions with Fe. The relatively increased Mn³⁺/Mn⁴⁺ ratio on MnO₂@FHNTs induced 𝜎^* orbital (e_g) occupation close to single electron, improving the OER performances. The MnO₂@FHNTs catalyst exhibited the reduced overpotential of 0.42 V (E vs. RHE) at 10 mA/cm² and Tafel slope of (99 mV/dec), compared with that of MnO₂ with unmodified HNTs (0.65 V, 219 mV/dec) and pristine MnO₂ (0.53 V, 205 mV/dec). The present study provides simple and innovative method to fabricate nano fiberized OER catalyst for a broad application of energy conversion and storage systems.