The development of information and communication technology has been changing not only the lifestyle of modern people but also the educational environment at a striking speed. E-learning, which uses computers and the Internet to learn in class, has already become a common learning method, and the development of such information and communication devices provides both teachers and learners with opportunities to experience a new teaching and learning environment [1]. The global pandemic and spread of COVID-19 have accelerated the convergence of technology with the classroom in response to an emergency where the sustainability of education is at stake. With the recent innovative progress in digital technology, the use of digital devices today has penetrated into all aspects of our lives. Recently, mobile phones have become a must-have item for people living in the era of the digital revolution. Mobile phones are equipped with multitask functions such as wireless computer activity, phone function, camera function, memo function, and personal information management function without time and space restrictions. In addition, a lot of activities are possible with mobile phones, such as listening to music, watching video clips, using a navigator in driving, taking photos and videos, checking an e-calendar, taking notes, reading an e-book, and playing mobile games. Therefore, it can be said that mobile phones can be utilized as a new educational tool that can accelerate a new type of mobile learning environment [2]. Mobile devices are not only replacing traditional learning tools but are also being recognized as an expanded learning tool for the digital learning environment, which requires new teaching and learning functions [3]. Moreover, the characteristics of portable digital devices enable learner-centered education by enabling cooperative learning through ubiquitous interaction beyond face-to-face relationships in the classroom [4]. Integrating mobile phones in learning and teaching has received favorable responses from both educators and students [5]. Research results show that mobile devices could boost learner motivation, make the learning process more engaging, and help students acquire knowledge in an entertaining way [6].

In the field of English as foreign language education (EFL), there is no exception in efforts to integrate technology into the field of language learning and teaching [7]. With the development of the ICT industry, interest in mobile learning in the field of English teaching and learning is growing, and research is also being actively conducted ^[8][9][10][8,9,10]. As a result, the extensive use of technology-integrated instruction has made it possible for EFL learners to experience the diverse capabilities of technology in their language learning [11]. One of the most valuable affordances of mobile phones is situated learning [12]. In situated language learning environment, language learners can act as active constructors of their own knowledge as they learn to understand their own needs and develop learning styles and strategies. English communicative competence is best acquired within authentic contexts, in which students can be involved in realistic language learning tasks [13]. Technology-integrated instruction can help the students focus on the situated learning context in language learning and knowledge construction. Integrating language learning activities into real-world settings holds the potential to make learning more relevant and enjoyable [14]. With the more learner-centered innovative approaches of new technologies, language learners can have opportunities to achieve communicative competence while engaging in authentic communication in relevant and meaningful contexts [15]. Utilizing digital devices can support language learners in acquiring communicative competence to meet their learning needs and to engage them in authentic communication from meaningful and sustainable perspectives.

Incorporating digital devices, such as mobile phones or pads, into the language learning process has potential as an innovative language learning and teaching method due to several aspects, such as portability, agility, and connectivity [16]. As using mobile phones has become an integral part of everyday life for most college students, educators and researchers have been scrutinizing how to integrate digital smart devices into classroom procedures. The widespread use of smartphones among college students has prompted teachers to explore how this digital technology can help enhance learning motivation and maintain students’ sustainable learning experiences [17].

2. REnhance Learning Experience with Mobile-Assisted Language Learning

With the growth of information and communication technology, technology-enhanced language learning has been increasingly regarded as a successful way to support learners with more interconnecting and collaborative language learning environments. Since smartphones have recently become an indispensable item in modern society, mobile-assisted language learning (m-learning) has been introduced to assist students’ language learning with the convenient features of digital devices and mobile technologies ^[6][18][6,18]. In particular, in the situation in which schools have been shut down due to the global COVID-19 pandemic and the sustainability of education has been threatened, the role of m-learning becomes even more important to provide quality education to students outside of school and help them to continue their self-directed learning. Self-directed learning is the concept of autonomous learning outside the classroom dimension [19]. When schooling is threatened and too limited to allow meaningful learning to happen, as it is today, it is crucial to utilize the alternative educational resources available outside the classroom. The accessibility and flexibility of the mobile-assisted language learning environment provides students with more authentic learning opportunities, making it easier to adapt to unfamiliar learning experiences. This is why technology-enhanced m-learning is inevitable for sustainable self-directed learning [20]. M-learning can support students to develop digital literacy and technology competence. It also provides a learner-centered and self-directed learning environment where learning is autonomous and sustainable [21]. The ICT Development Index (IDI) is a composite index with 11 indicators combined into a composite score. It is used to monitor and compare developments in information and communication technology between countries over time. According to the International Telecommunication Union (ITU) report, South Korea placed 1st in the IDI (ICT Development Index) ranking among 147 countries in 2016 and 2nd out of 176 countries in 2017 [22]. Korea also shows higher levels of ICT accessibility, network infrastructure, ICT intensity of society, and ICT influence in digital literacy. Korea ranks first in the world for smartphone ownership and internet use. Nine out ten Korean adults make use of the internet and own a smartphone. Korea is also known as the country with the best internet connection in the world. It showed the highest internet penetration rate at 96 percent followed by the Netherlands and Australia (both at 93 percent) [23]. According to the report by the US-based Pew Research Center, South Korea recorded the highest smartphone ownership rate of 94 percent followed by Israel (83 percent) and Australia (82 percent) as seen in Figure 1 below [23]. As can be seen from Figure 2 below, this statistic shows the smartphone ownership rate of internet users in Korea as of September 2020 by age group. It shows that 99% of people aged 20–59 have smartphones and utilize the internet, and 94.7% aged 6–19 and 93.1% aged 60–69 have smartphones and utilize the internet [24]. For university students in particular in South Korea, the use of digital technology and smartphones has become an inseparable part of their daily activities. Hence, instructors at college have investigated teaching methods to transform their students’ enthusiasm for using digital devices into a pedagogic paradigm. Researchers and instructors have also investigated educational designs that can leverage the beneficial elements of smartphone applications to tailor the needs and interests of tech-savvy, digitally native college students. Thanks to the all-encompassing capabilities of smartphones, mobile learning has become a prominent element of the e-learning movement. Smartphone integration gives students easy access to language learning resources and allows them to interact with teachers and fellow students whenever and wherever they want [25]. Smartphones can be useful and convenient learning tools in language education because they have features such as Internet connectivity, voice and text messaging, and audiovisual recording capabilities. All the characteristics of mobile phones can be successfully implemented in the learning and teaching of a new language. Table 1 classifies the characteristics of mobile learning into six categories [20]. Interrelated factors, such as learner characteristics, teachers’ educational beliefs, the context of a particular course, and learning assessment, have played an essential role in the success of mobile learning. The most important characteristics of mobile learning are accessibility, mobility, interactivity, and flexibility [26]. Smart education has the advantage of allowing users to access the Internet anytime, anywhere using digital devices such as mobile phones and tablets, and this enables language learners to choose the learning contents and learning environment that suit their learning style and strategy. Most digital devices are equipped with innovative and cutting-edge technologies, such as high-quality camera features, voice recording capabilities, good storage capacity, proper screen sizes, and a longer battery life, so language educators have been working to increase the use of technology in the classroom [27]. In addition, these days, it is possible for learners to perform various language learning activities, such as language dictionary searches, translation, real-time tutoring, and recording using various mobile applications. These features are attracting attention as useful smart learning tools that can increase the efficiency of foreign language learning because they allow learners to consume the necessary language learning contents at their own pace [28]. Digital devices can only make students’ language learning experience itself truly mobile when language teachers are able to make use of creative learning tasks that allow their students’ learning experience to extend beyond the classroom. With such instructional strategies, students expressed their enjoyment of being able to learn and practice a language outside of the classroom with the support of mobile phones [29]. Mobile learning can provide students with a more exciting learning environment. It can also allow students to collaborate with immediate feedback, dynamic classroom interactions, and improved learning outcomes [30]. Other research has shown that the integration of mobile phones and digital applications into EFL education can improve EFL learners’ speaking, reading, grammar, and writing skills ^[5][31][5,31]. To develop EFL students’ English communication competence and to guarantee sustainable self-directed learning experiences, smart technologies should be integrated into existing educational curricula to create more opportunities for authentic social interaction and meaningful negotiation experiences [32].