The MiG-21 first came into service in the late 1950s and saw considerable service in the Vietnam War. The KPAF is estimated to be the fifth-largest air force in the world, with 110,000 service personnel and 820 combat aircraft. North Korean leader Kim Jong Un watches as a female fighter jet pilot performs drills. But there is considerable doubt as to how many of those aircraft, some of them dating back to the 1950s, are airworthy. Visitors to Pyongyang are often surprised by the sight of antiquated biplanes on the runway.
Research literature, recent books, and common sense, all point to the fact that there are different types, or styles, of ADHD. In the past we referred to Attention Deficit Disorder: Inattentive Type, or Impulsive/Hyperactive Type, or a Combined Type.
Doctors may classify symptoms as the following types of ADHD 1  : Combined type (inattentive/hyperactive/impulsive). 2  Children with this type of ADHD show all three symptoms. 3  This is the most common form of ADHD. 4  Hyperactive/impulsive type.