CREATE TABLE table_298883_5 (dimensions VARCHAR2, reverse VARCHAR2)

What are the dimensions of the coin with western sea barrage and locks at taedong gang on the reverse side?
SELECT dimensions FROM table_298883_5 WHERE reverse = "Western sea barrage and locks at Taedong Gang"
SELECT "dimensions" FROM "table_298883_5" WHERE "Western sea barrage and locks at Taedong Gang" = "reverse"