• Applied Chemistry for Engineering
• /
• v.32 no.3
• /
• pp.283-289
• /
• 2021

Adsorption characteristics of carbol fuchsin (CF) dye by coal-based activated carbon (CAC) were investigated using pH, initial concentration, temperature and contact time as adsorption variables. CF dissociates in water to have a cation, NH₂⁺, which is bonded to the negatively charged surface of the activated carbon in the basic region by electrostatic attraction. Under the optimum condition of pH 11, 96.6% of the initial concentration was adsorbed. Isothermal adsorption behavior was analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. Langmuir's equation was the best fit for the experimental results. Therefore, the adsorption mechanism was expected to be adsorbed as a monolayer on the surface of activated carbon with a uniform energy distribution. From the evaluated Langmuir's dimensionless separation coefficients (R_L = 0.503~0.672), it was found that CF can be effectively treated by activated carbon. The adsorption energies determined by Temkin and Dubinin-Radushkevich models were E = 15.31~7.12 J/mol and B = 0.223~0.365 kJ/mol, respectively. Therefore, the adsorption process was physical (E < 20 J/mol, B < 8 kJ/mol). The experimental result of adsorption kinetics fit better the pseudo second order model. In the adsorption reaction of CF dye to CAC, the negative free energy change increased as the temperature increased. It was found that the spontaneity also increased with increasing temperature. The positive enthalpy change (40.09 kJ/mol) indicated an endothermic reaction.

• Journal of Venture Innovation
• /
• v.6 no.1
• /
• pp.75-93
• /
• 2023

As non-face-to-face contact was activated due to the progress of the 4th Industrial Revolution and COVID-19, the government's civil service was also rapidly reflecting this phenomenon. However, there were cases in which it was quite burdensome and rather uncomfortable for the elderly who were relatively alienated from the digital culture. Therefore, in this study, we tried to empirically analyze the factors that affect the use of government 24(a government civil integration service) by the elderly. For this purpose, the characteristics of the elderly and the characteristics of services were paid attention. As the characteristic factors of the elderly, cognitive characteristics, psychological characteristics, and physical characteristics were derived, and as service characteristics, usefulness, ease of use, security, and government support were derived when using government 24. The effect of these factors on the intention to use Government 24 was empirically analyzed. For empirical analysis, a survey was conducted targeting the elderly in their 60s and older, and 250 valid sample were used for analysis. The analysis results were as follows. Among the characteristics of the elderly, cognitive characteristics, psychological characteristics, and physical characteristics were all found to had a significant negative (-) effect on the intention to use Government 24. On the other hand, usefulness, ease of use, and government support were found to had a significant positive (+) effect on the intention to use government 24. On the other hand, security was not tested for a significant relationship with government 24 use intention. Among the variables that have a significant impact, the psychological characteristics of the elderly had the greatest impact on the intention to use Government 24. Usefulness, cognitive characteristics, physical characteristics, ease of use, and government support were in order. The fact that this study conducted an empirical analysis by combining the characteristics of the elderly and the characteristics of services was meaningful at the academic level. In addition, considering that psychological characteristics appeared to be the most important factor, it seemed necessary to consider these points to promote the use of Government 24 by the elderly.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.24 no.4
• /
• pp.337-349
• /
• 2008

Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in delayed loading conditions. A total of 36 solid screw implants (diameter 3.75 mm, length 10mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium Implants served as control. Gold crowns were inserted 3 months. Radiographic assessments and stabilitytests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 1 and 3 months after loading. Histological observations and morphometrical measurements were also performed. Of 36 implants, 32 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels (p=0.413) and RFA values. The mean BIC % in the Mg-implants was $54.4{\pm}20.2%$. The mean BIC % in the turned implant was $48.9{\pm}8.0%$. These differences between the Mg-implant and control implant were not statistically significant (P=0.264). In the limitation of this study, bone-to-implant contact (BIC) and bone area of Mg-incorporated oxidized implant were similar to machine-turned implant. The stability analysis showed no significantly different ISQ values and marginal bone loss between two groups. Considering time-dependent bone responses of Mg-implant, it seems that Mg-implants enhanced bone responses in early loading conditions and osseointegrated similarly to cp Ti implants in delayed loading conditions. However, further investigations are necessary to obtain long-term bone response of the Mg-implant in human.