ABSTRACT
Under the background of global cross-border mobile commerce (m-commerce) integration, the importance of cross-border payment research is becoming increasingly prominent and urgent. The important value of this study is to empirically research the influence power of key elements in using two different mobile payment (m-payment) platforms in Korea. The extended unified theory of acceptance and use of technology (UTAUT2) has been widely applied in various studies because of its strong interpretive power. In Korea, there are a few empirical studies on Chinese users. Based on a survey of 908 Chinese participants (486 WeChat Pay's Chinese users and 465 Kakao Pay's Korean users) in Korea, this study is one application extending UTAUT2 by incorporating multi-group and multi-model constructs: UTAUT2, information system success (ISS) model, and an initial trust model (ITM), considering a multi-group analysis with some mediating variables (payment difference). By comparing the two different payment platforms' characters, this manuscript provides a set of targeted measures to ensure Chinese WeChat Payment platform decision-makers create effective long-term strategic policies for cross-border m-payments in Korea, and eventually, benefit cross-border m-commerce and economic cooperation in Southeast Asia.
ABSTRACT
Along with the increase in the demand for existing colored concrete, the demand for secondary concrete products of various colors is also increasing. However, the initial surplus water in mortar causes the internal calcium component to leach out and contaminate the surface, and the hardening of concrete that contains pigment is generally slower than that of normal concrete. This study was to evaluate the physical properties of mortar colored by carbon amino silica black (CASB), using a methyl cellulose (MC) polymer to reduce surface efflorescence and increase early strength by means of steam curing. MC modifies the mechanical properties of mortar by forming a polymer film, which prevents the soluble calcium from migrating to the surface and reduces whitening in steam cured mortar. However, steam curing significantly decreased the strength with increasing MC content when CASB content was high.
ABSTRACT
Environmentally friendly superhydrophilic and superhydrophobic sponges were synthesized using a one-step approach for oil/water separation. A superhydrophilic or superhydrophobic sponge (MFS/CC-DKGM or MFS/CC-PDMS) was synthesized by one-step coating of melamine formaldehyde sponge (MFS) with a mixture of calcium carbonate (CC) rods and deacetylized Konjac glucomannan (DKGM) [or polydimethylsiloxane (PDMS)]. The MFS/CC-PDMS showed excellent absorption capacity, which reached 52â»76 g/g following immersion into various types of oil/water mixtures. Furthermore, the MFS/CC-DKGM and MFS/CC-PDMS exhibited excellent water- and oil-flux performances, which reached 4,702 L/m² h and 19,591 L/m² h, respectively, when they were used as filters. The MFS/CC-DKGM and MFS/CC-PDMS maintained their wettability characteristics relatively well after the chemical, thermal, and mechanical stability tests.
ABSTRACT
A convection heat treatment that can replace existing chemical oxidation methods was developed for the preparation of hierarchically oxidized Cu meshes with various surface morphologies, representing a very simple and green route that does not involve toxic chemicals. Three types of Cu meshes [bumpy-like (BL) and short and long needle-like (NL) structures] exhibited similar separation efficiencies of 95-99% over 20 separation cycles, as indicated by their similar water contact angles (WCAs; 147-150°). However, these Cu meshes exhibited different flux behaviors. Excessively rough and excessively smooth surfaces of the Cu mesh resulted in increased resistance to flow and to a decrease of the penetration of oil. A surface with intermediate smoothness, such as the BL-Cu mesh, was necessary for high flux over a broad range of oil viscosities. Furthermore, a less rough surface was more suitable for the separation of highly viscous oil. Computational fluid dynamics (CFD) simulations were carried out to support our experimental results. The BL-Cu meshes also showed outstanding mechanical stability because of their low resistance to the flow of fluids.
ABSTRACT
BACKGROUND: Validated simple calcium questionnaires are available to assess the intake of calcium and vitamin D in western countries, but they are not appropriate for Koreans since dairy products are not the major source of calcium and vitamin D in Korea. Thus, the objective of the present study was to develop and validate a simple and easy food frequency questionnaire (FFQ) of calcium and vitamin D for Korean. METHODS: Two hundred and fifty-six women were asked to complete the validated FFQ used by the Korean National Health and Nutrition Examination Survey (KNHANES) and a newly developed FFQ, the Korean Calcium Assessment Tool (KCAT), which contain the 7 food groups with 24 categories of 45 food items that are consumed frequently by Koreans. RESULTS: Calcium intake was not significantly different between the two methods; Pearson's correlation coefficient of 0.98 indicated a positive correlation, and Cohen's kappa coefficient of 0.78 indicated the subjects were correctly classified. Bland-Altman plot also showed that the mean differences of the calcium intake as assessed by the two methods were in high agreement. However, the vitamin D intake assessed by KCAT was significantly higher than that assessed by the FFQ used in KNHANES. The vitamin D intakes as assessed by the two methods were positively correlated but the two methods were in moderate agreement. CONCLUSIONS: The results suggested that the newly developed KCAT was a valid tool for assessing the calcium intake in Korean women, but it might overestimate the vitamin D intake.
