This study is an empirical research that examines the factors affecting service loyalty aimed at users of social service voucher system in the perspective of institution performance. First, this research analyzes the mediating effect of relationship quality on the relationship between social service quality perceived by service users and service loyalty, through the structural relationship between variables from the perspective of their institutional performance. To this end, this study investigates the direct and indirect impacts among the variables. Above all, it examines the moderating role of switching barriers between relationship quality and service loyalty in the field of social services and also finds the existence of moderating effects according to the characteristics of users groups.
For empirical analysis, data is collected from 719 people including 242 people from 20 institutions of long-term care service for the elderly, 256 people from 13 institutions of Personal Assistance Service, and 221 people from 20 institutions of psychological support services for children and adolescents located in Busan. AMOS 22.0 is used for the analysis of the structural equation model, and SPSS 22.0 for the hierarchical regression analysis. The findings are as follows.
First of all, this study analyzes the direct and indirect impact of social service quality on the loyalty of service users through the mediation of relationship quality, which is composed of satisfaction, trust, and commitment; the findings are as follows: First, social service quality has the greatest direct impact on satisfaction among factors to do with relationship quality, followed by commitment and trust.
Second, this study examines the mediating effect of relationship quality between the social service quality perceived by users and the loyalty of users. Social service quality has a significant effect on the intention of reuse and on word-of-mouth intention. It is also discovered that social service quality has an important effect on service loyalty through mediation of relationship quality. Social service quality has a direct impact on the order of trust, satisfaction, and commitment in relationship quality, but is also an important factor that has direct and indirect impacts on intention to reuse, and word-of-mouth intentions. This is how this study proved that the trust, satisfaction, and commitment of relationship quality have a partial mediating effect between social service quality and intention of reuse, and between social service quality and word-of-mouth intentions.
This means that when social service quality is high, the factors concerning relationship quality generally improve and service loyalty is enhanced. This can be interpreted that when the users receive services whose sociality and expertise are guaranteed, when they perceive that the providers are doing their best and can be trusted, when they are generally satisfied with the services, and when they are committed to the institutions and providers, they tend to have more reuse and word-of-mouth intentions.
Next, this study analyzes the moderating role of the switching barriers in the relationship between relationship quality and service loyalty. First, the existence of a moderating effect of switching cost between relationship quality of social service users and service loyalty is found. Switching cost has a moderating effect that weaken the positive impact on the relationship between satisfaction, trust, and commitment and intention of reuse, and between satisfaction and trust and word-of-mouth intention. The higher switching cost, the lower will be the impact of satisfaction, trust, and commitment on intention of reuse and impact of satisfaction and trust on word-of-mouth intention.
Second, is found that attractiveness of alternatives has a moderating effect on the relationship between relationship quality of social service users and service loyalty. This effect strengthens the positive impact on the relationship between satisfaction and intention of reuse, between trust and intention of reuse, and between satisfaction and word-of-mouth intention. The higher attractiveness of alternatives, the higher will be the impact of satisfaction and trust on intention of reuse and word-of-mouth intention.
this study compares the moderating effects of switching barriers in the domain of social services, and discovers that, generally, switching cost has more effect than attractiveness of alternatives. This may be because users do not perceive attractiveness of alternatives more than switching cost, which led to attractiveness of alternatives having a lower moderating effect.
As for the moderating effect between relationship quality and service loyalty, it''s found that trust is affected more by switching cost and attractiveness of alternatives than by satisfaction or commitment. Moreover, the moderating effect of switching barriers is higher in the relationship with reuse intention than in the relationship with word-of-mouth intention. Examination of switching barriers'' moderating effects on the relationship between relationship quality in social services and service loyalty shows that there is no moderating effect of switching cost on the relationship between commitment and word-of-mouth intentions, and no moderating effect of attractiveness of alternatives on the relationship between commitment and intention of reuse, commitment and word-of-mouth intention, between, or between satisfaction and word-of-mouth intention.
In addition, this study analyzes whether there is a difference in the effects of switching barriers on the relationship between of relationship quality and service loyalty according to the type of services that are provided in keeping with the characteristics of users groups. First, concerning the long-term care service for the elderly, switching cost has a weakening moderating effect only on the relationship between trust and reuse intention, and between trust and word-of-mouth intention. Attractiveness of alternatives has a strengthening moderating effect only on the relationship between trust and word-of-mouth intention.
Concerning Personal Assistance Service, switching cost has a weakened moderating effect on the relationships between satisfaction, trust, and intention of reuse, and between satisfaction, trust, and word-of-mouth intention. Attractiveness of alternatives has a strengthened moderating effect on the relationships between satisfaction, trust, and intention of reuse, and between satisfaction, trust, and word-of-mouth intention. As for the psychological support services for children and adolescents, there wis no moderating effect of switching barriers. Instead, satisfaction, trust and commitment of relationship quality have an important impact on reuse and word-of-mouth intentions.
In conclusion, in order to enhance performance from the perspective of the market, the mediating effect of relationship quality between the social service quality and service loyalty, and the moderating effect of switching barriers between relationship quality and service loyalty must be treated as important. Therefore, the policies of social services should pay particular attention to addressing relationship quality and switching barriers in consideration of the roles that switching cost and attraction of alternatives play at the policy design stage. To this end, organizations should provide education on the sensitivity of relationships for the service providers in order to improve relationship quality. The difference in the roles of switching barriers according to service type shows that switching barriers must be handled with consideration to the characteristics of users groups.

Key words : social service quality, relationship quality, satisfaction, trust, commitment, switching barriers, switching cost, attractiveness of alternatives, service loyalty, intention of reuse, word-of-mouth intention.