Subjects’ general characteristics, included age, sex, education level, average monthly income, General health condition. The unit of monthly income is 10,000 Korean won. Educational levels were categorized as low for subjects educated to high school level or lower and high for subjects educated to college level or higher. Job stress was set to ‘Low’ for 1 ~ 2 points and ‘High’ for 3 ~ 5 points. General health condition is very good, good, normal is defined as Good, bad, and very bad as Bad.