In this paper analyzed the features of how native Korean speakers (K) and native Vietnamese Korean learners (VKL) organize the Apology conversation, focusing on the functional phase. Based on the discourse analysis, a role play was conducted to collect data. In order to investigate the influence of social variables (social status, intimacy), learners' mother tongues and learners' Korean proficiency, different social variables were given in role-play situations, and learners' Korean proficiency was limited to intermediate and advanced levels. The results of analyzing conversations focusing on ‘Error Checking–Apology-Apology Acceptance’, which is the intermediate phase of Apology conversation, are as follows. First, in the Error Checking Phase, K tended to make indirect or preliminary remarks. In contrast, VKL immediately presented communication purposes, and advanced VKL tended to use indirect speech and additional statement. Second, in the Apology phase, the higher social status the other party has and the lower intimacy the two speakers has, the more passive K were. Interestingly, VKL showed the same pattern. For intermediate-level VKL, it was observed that the dialogue sequences were not completed. Third, in the Apology Acceptance phase, K repeatedly expressed apologies through complex dialogue sequences. However, VKL performed a concise conversation by simple dialogue sequences, and the intermediate-level VKL expressed ‘relief’ and ‘gratitude’.

In the current study, MIL-101(Cr)-SO3H[HCl] as metal-organic frameworks (MOFs) was fabricated via a hydrothermal method. The physicochemical properties of the synthesized material were characterized using XRD, FT-IR, FE-SEM, TEM, and BET surface area analysis. The XRD diffraction pattern of the prepared MIL-101(Cr)-SO3H[HCl] was similar to previously reported patterns of MIL-101(Cr) type materials, indicating successful synthesis of MIL-101(Cr)-SO3H[HCl]. The FT-IR spectrum revealed the molecular structure and functional groups of the synthesized MIL-101(Cr)-SO3H[HCl]. FE-SEM and TEM images indicated the formation of rectangular parallelopiped structures in the prepared MIL-101(Cr)-SO3H[HCl]. Furthermore, the EDS spectrum showed that the synthesized material consisted of the elements of Cr, O, S, and C. The fabricated MIL-101(Cr)-SO3H[HCl] was then employed as an adsorbent for the removal of Sr2+ and Cs+ from aqueous solutions. The adsorption kinetics and adsorption isotherm models were studied in detail. The maximum adsorption capacities of MIL-101(Cr)-SO3H[HCl] for Sr2+ and Cs+ according to pH (3, 5.3∼5.8, 10) were 35.05, 43.35, and 79.72 mg/g and 78.58, 74.58, and 169.74 mg/g, respectively. These results demonstrate the potential of the synthesized MOFs, which can be effectively applied as an adsorbent for the removal of Sr2+ and Cs+ ions from aqueous solutions and other diverse applications.