Granted Patent
Utility
US 6,026,892 · App. 08/927,542
Heat transfer tube with cross-grooved inner surface and manufacturing method thereof
Inventors:
Pyung Gon Kim, Kill Soon Kwak
Patented Case
View Patent ↗
Granted: Feb 22, 2000
Filed: Sep 11, 1997
Inventors
Pyung Gon Kim
Kill Soon Kwak
Assignee (at issue)
Poongsan Corporation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.