[Java] [Error] No EntityManager with actual transaction available for current thread

org.springframework.dao.InvalidDataAccessApiUsageException:
No EntityManager with actual transaction available for current thread
- cannot reliably process 'persist' call;
nested exception is javax.persistence.TransactionRequiredException:
No EntityManager with actual transaction available for current thread
- cannot reliably process 'persist' call

엔티티 메니저를 통한 모든 데이터 변경은 트렌잭션 아래에서 이루어져야함