Patents by Inventor Cheong J. Kang

Cheong J. Kang has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Door lock having security device
    Patent number: 5004278
    Abstract: An improvement of the door lock which is extensively used in all kinds of doors is disclosed which is characterized in that a security device is added to the existing door lock without modifying the constitution and the operating principle of the existing door lock, so that, once the security device is activated from the inside of the room, the door lock can never be opened by even the corresponding key and other means from the outside, thereby protecting the persons staying inside the room from the attempt of an unpermitted intruder.
    Type: Grant
    Filed: November 20, 1989
    Date of Patent: April 2, 1991
    Inventors: Cheong J. Kang, Seok J. Kang