In recent years, there has been significant academic and social interest in precarious employment (PE) (Benach et al., 2014). The standard employment relationship (SER) refers to a employment relationship in which employees are engaged in a stable, full-time, and permanent employment contract, entailing comprehensive legal rights and benefits (Schoukens and Barrio, 2017). However, the traditional employee-employer relationship has undergone rapid changes in the labor market recently. The advancement of digital technology has brought about Industry 4.0, leading to a noticeable increase in the proportion of non-standard labor, such as gig work (Scully-Russ and Torraco, 2020). The changes in economic structure and the expansion of PE are accompanied by a rise in inequalities in health and wealth within the working population (Benach et al., 2016; Muntaner, 2016). Consequently, researchers in the fields of occupational safety and health have begun to measure and operationalize PE using a multidimensional approach (Bodin et al., 2020). Traditionally, PE has referred to temporary employment as a counterpart to permanent employment (Vives et al., 2020b). However, a recently proposed conceptual framework by Kreshpaj et al. demonstrates that PE is a multifaceted construct with three primary dimensions (employment insecurity, income inadequacy, and lack of rights and protection) and corresponding subthemes (Kreshpaj et al., 2020). Specifically, employment insecurity comprises contractual relationship insecurity, contractual temporariness, underemployment, and holding multiple jobs. Income inadequacy comprises income level and income volatility, while the lack of rights and protection includes factors such as the absence of union representation, social security, regulatory support, and workplace rights.

Previous studies, primarily relying on unidimensional measures of PE, have demonstrated their association with poor mental health (Jaramillo et al., 2022; Koseoglu Ornek et al., 2022; Ronnblad et al., 2019). For instance, a meta-analysis by Ronnblad et al. showed that job insecurity is positively associated with depressive symptoms, anxiety symptoms, and psychotic drug use (Ronnblad et al., 2019). However, measurements that encompass multiple dimensions of PE have been shown to be more sensitive to workers' health outcomes than unidimensional measures (Vives et al., 2020a; Vives et al., 2020b). For instance, previous studies utilizing multidimensional measures of PE showed that high levels of PE are linked with occupational injuries, (Koranyi et al., 2018), increased body weight (Oddo et al., 2023), and stroke (Matilla-Santander et al., 2022). Additionally, previous studies have consistently shown that the high Employment Precariousness Scale (EPRES) is positively associated with workers' mental health problems (Jaramillo et al., 2022; Jonsson et al., 2021a; Padrosa et al., 2022).

Although several studies have utilized a summative score approach (e.g., EPRES), an alternative methodology that has been widely employed for comprehending PE is a typological approach that uses latent class analysis (LCA) to identify various types of PE among workers (Cho, 2020; Jonsson et al., 2021b; Jonsson et al., 2021c; Peckham et al., 2022a; Van Aerden et al., 2017; Van Aerden et al., 2014). While each methodology has its unique objectives, the typological approach offers distinct advantages in profiling the employment conditions of the targeted working population and assessing health implications of PE (Jonsson et al., 2021b). Previous studies have shown that workers belonging to PE typologies characterized by high employment insecurity or low income are more likely to report poor self-rated health than workers belonging to typologies characterized by low employment insecurity, high income, and high levels of workers' rights and protections (Cho, 2020; Jonsson et al., 2021c; Van Aerden et al., 2017).

Despite several studies on the association between PE and mental health among workers, the current literature has some major limitations. First, most studies on PE have been conducted in Western countries, such as Europe and the United States, and the typologies of PE in Asian countries and their associations with health have not been investigated. Commonly used analytical tools to explore the health impacts of PE, such as the EPRES (Vives et al., 2010), Precarious Employment Scale (Oddo et al., 2021), and Swedish Register-based Operationalization of Precarious Employment (Jonsson et al., 2021b), have been developed in Western countries, but conceptualization and operationalization of PE have been understudied in the context of Asia. Given that labor environments and policies differ across regions, examining how PE manifests and affects health in the Asian context is important, both academically and policy-wise (Kang, 2023). Moreover, as previous studies on the mental health impact of PE have primarily focused on employment insecurity, there is a lack of evidence regarding other components of PE, such as the lack of rights and protection (Jaramillo et al., 2022; Ronnblad et al., 2019).

Therefore, the objectives of this study are threefold: (i) to operationalize PE in the context of Korea using a theory-based conceptualization; (ii) to identify distinct patterns of employment conditions among Korean wageworkers through a typological approach; and (iii) to investigate the association between PE and mental health outcomes among Korean wageworkers.