Modern industry was transformed to the era of Information & Communication Technology(ICT) while Information Technology(IT) age was evolved. The rapid development of information and communication technology has brought in great changes in the global industry. The personal computer and wired Internet started to change the business types, and in the end the emergence of wireless Internet and smartphone created a new industrial paradigm accordingly. The creation of smartphone makes a lot of new businesses created by the paradigm shift which transcends time and space that are accessible anywhere and anytime through the ubiquity, portability, and wireless connection. In other words, the ICT era has been flourished by the growth of the network, that started by the widespread use of personal computers, and the popularization of smartphones of the IT era and now it is moving toward a connected generation. The advent of the Web 2.0 era has led to the rapid growth of SNS like KakaoTalk, and LINE, etc. in Korea and Twitter, Facebook, and Instagram, etc. globally, and various businesses have been created and utilized this platform. In 2007, Facebook pursued an open platform and started the social platform era.
While Facebook is a global social platform, there is Kakao in Korea. These social platforms has rapidly grown along with the popularization of smartphone and the number of users worldwide is at 1.96 billion(as of 2015) and estimated to be around 2.44 billion in 2018 with (eMaketer, Starbase, 2015). The social platforms create and connect diverse businesses accordingly beyond simple social networks, that is a communication stage. However, the research on the social platform is in the beginning stage. From this point of view, this study develops and suggests the leading factors and outcome factors, focusing on the key factors that could influence the users’ intention to continuous use of the social platform.
The reliability, validity and explanatory power of each variable were verified through the empirical process. In order to find out the characteristic variables of social platforms, this study conducts a questionnaire survey on the users of the social platform and the previous research. As a result, this study develops the characteristic variables that explain users enjoy 'fun' through entertainment contents such as video contents(UCC) and social games in addition to communication (story) through SNS which is the basis of social platform. In other words, this study examines what variables actually affect the intention to continuous use through fun. Theoretically, this study derives the fun factors from the intention of continuous use of the social platform based on the fun theory by Malone, T.W. and Lazzaro, N., and applied to the extended technology acceptance model (ETAM) with perceived ease and perceived usefulness. In other words, this study derives the emotional variables (challenge, curiosity, fantasy, and relationship) which are independent variables of this study and apply them to the technology acceptance model that extended the perceived fun factor in addition to the perceived ease and perceived usefulness. The purpose of this study is to suggest a method for businesses to match the expectation level and the perception level of the social platform to the consumers. On the basis of the findings above, the statistical analysis was performed using SPSS 22 and AMOS 22 after establishing the theoretical study model. With regard to the analysis method, this study performed the verification of convergent validity and discriminant validity of the measurement index by using the descriptive statistics analysis, the reliability test, the exploratory factor analysis, and the confirmatory factor analysis of the research model. The causal relationship was empirically analyzed by verifying the structure model for the measurement items that the verification of validity and reliability were completed.

The implications for the empirical analysis of this study are
First, this study empirically examines the causal relationship between the social platform and the extension technology acceptance model, and present the user influence factors of the social platform to the social platform operators as the fun factors and causal factors.
Second, this study defines the sense of challenge, curiosity, fantasy, and relationship as composing measurement items of the fun theory. It was analyzed that the curiosity and relationship affected the perceived fun factors of social platform whereas the challenge and fantasy did not have positive effects on them. This suggests that challenge and fantasy were related to the creation of content on a social platform, and the survey results suggest that only 14.5% of users of the social platform actually created the contents.
Third, as a result of the study on the intention to use perceived ease and perceived usefulness with perceived fun factors, this study derived conclusion that both perceived fun and perceived ease have positive effects on continuous intention to use, but perceived usefulness has no effect.
Fourth, this study concluded that the perceived fun factors have positive effects on both the effects perceived usefulness and perceived ease.
In addition, the fit of the measurement model and the fit of the model to the hypothesis test are around the general recommendation level, so that the fit of the research model is high.

The implications of the theoretical aspects of the results of this study
First, this study is meaningful in presenting and proving the factors affecting the continuous use of the social platform users through theoretically, the proven variables and measurement items through the empirical analysis process, and perceived ease of use, and perceived usefulness through structural equation modeling.
Second, this study set up the theoretical foundations for the empirical study in this field by developing the sense of challenge, curiosity, fantasy, and relationship based on the fun theory as sub-factors of perceived fun factors, and establishing the definition and the reliable and valid measurement items.
Third, social aspects of social platform are more meaningful for continuous use when considering perceived fun factor of social platforms as content aspect of challenge and fantasy, and social aspect of curiosity and relationship. This will be an opportunity to establish the play and fun theory on social platform, unlike the conventional play theory and fun theory of digital content (video and game).

The practical implications of this study are
First, this study establishes the foundation for the empirical study in this field by investigating the relationship between the fun factor of the social platform, the user perception elements, and the dependent variables, and by suggesting the measurement items for variables with the definition, reliability, and validity. It is also expected to contribute the establishment of social platforms and marketing strategies by used as strategic tools of platform business for prospect social platform operators.
Second, this study shows that the curiosity and sociality have positive effects among the fun factors of social platform. This indicates that curiosity and relationship factors are important when users utilize social platforms. Therefore, social platform providers should focus on creating new communities and maximizing new human connections in delivering their services.
Third, the research suggests that the challenge and fantasy do not have a positive effect on the fun factors of the social platform. This implies that users need to build an environment that would stimulate more active contents on the social platform. It can be interpreted as the users would have continuos intention to use only when the fun is maintained in communicating with each other by attracting attention with something unique or behavior like formation of own image while using the social platform.
Therefore, social platform operators should concentrate their efforts to find motivational method to stimulate the creation of contents in the social platforms.

The contributions of this study to social platform providers and consumers are
First, social platforms are aiming for platform businesses beyond social network services, but they have not yet been able to commercialize them for young college students. This demonstrates that the social platforms is at the stage of ease and fun. It can be also seen that they do not provide the further usefulness as the platform businesses for users.
Second, the ratio of users creating contents directly on the social platform is low. This can be interpreted as it affects on usability, suggesting lack of diversity in social platforms.

The results of this study can be summarized as follows.
Although social platform operators should faithfully perform the standard features of SNS, they also should provide various profitable contents in order to enhance platform the business and the strategic plans in order to expand their ratio of user creating their own contents. Since the contents consumers cannot exist without the creators, it is necessary to raise the effects of overall fun factors by increasing the ratio of creators further by the motivations. In addition, they should consider to enhance the usefulness of the social platform. Currently the social platform is primarily considered as a simple and enjoyable tool, but it is necessary to develop and apply the useful and creative contents that provide useful values for the users as a true platform in the future.

Key words: Platform, Social platform, Extended technology acceptance model, Fun, Play, Continuous intention to use, Challenge, Curiosity, Fantasy, Relationship, People.