The purpose of this study was to investigate factors influencing lifetime smoking and current smoking among adolescents in South Korea.

Hierarchical logistic regression was conducted based on complex sample analysis using statistics from the 10th (2014) Korea Youth Risk Behavior Web-Based Survey. The study sample comprised 72,060 adolescents aged 12 to 18.

The significant factors influencing adolescent lifetime smoking were female gender, older age, higher stress, higher weekly allowance, lower economic status, living apart from parents, parental smoking, sibling smoking, peer smoking, observation of school personnel smoking, and coed school compared to boys' school. The significant factors influencing adolescent current smoking were female gender, older age, higher stress, higher weekly allowance, both higher and lower economic status compared to middle economic status, living apart from parents, parental smoking, sibling smoking, peer smoking, observation of school personnel smoking, and coed school compared to boys' school.

Factors identified in this study need to be considered in programs directed at prevention of adolescent smoking and smoking cessation programs, as well as policies.

The purpose of this study was to investigate factors that influence sexual intercourse among middle school students in South Korea.

Using statistics from the 8th (2012) Korea Youth Risk Behavior Web-based Survey, hierarchical logistic regression analysis was conducted. The study sample comprised 37,297 middle school students aged primarily 12 to 15.

The significant predictors of sexual intercourse were grade, ever smoking, ever drinking, habitual or purposeful drug use, economic status, weekly allowance, cohabitation with family, and type of school.

The results suggest that intensified sex education is needed not only in the 1st grade of middle school, but also in the upper grades of elementary school. Sexual health interventions for high-risk groups may be needed, given the factors predicting sexual intercourse.