Pokayoke in IUJ - 1

Product Design : Door knob/ lock
Location : All IUJ student dormitory rooms
Mistake Prevention : Accidentally locking the room from inside

The door lock in IUJ student dormitory room (SD2, SD3) is designed in such a way that it prevents somebody to accidentally lock the room from inside, when he or she wants to leave the room. Consider a typical bad example of lock design using a button mechanism: a button is accidentally pressed from the knob (inside the room). When the door is closed, it is locked from inside. However, the lock design of IUJ dormitory room doesn’t use the pressing button mechanism. When a person wants to leave his room, he can only lock the door using his key. Since there is no other ways to lock the room except by using key, this lock design prevents him from accidentally locking his room from inside.

About Pokayoke
Poka-yoke (ポカヨケ?) (IPA: [poka joke]) is a Japanese term that means "fail-safing", "Foolproof" or "mistake-proofing" — avoiding (yokeru) inadvertent errors (poka)) is a behavior-shaping constraint, or a method of preventing errors by putting limits on how an operation can be performed in order to force the correct completion of the operation. The concept was formalised, and the term adopted, by Shigeo Shingo as part of the Toyota Production System. Originally described as Baka-yoke, but as this means "fool-proofing" (or "idiot proofing") the name was changed to the milder Poka-yoke.

(source: Wikipedia)