Issued Patents 1989
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4842447 | Manufacturing method and device of hollow-typed reverse circulating piles | — | 1989-06-27 |
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4842447 | Manufacturing method and device of hollow-typed reverse circulating piles | — | 1989-06-27 |