Abstract: The present invention provides a piston apparatus having an oil scraper ring, by which smoke due to incomplete combustion of fuel is prevented in a manner of preventing oil attached to an inner cylinder wall and piston in an internal combustion engine from rising into a combustion room by a reverse pressure and preventing a blow-by phenomenon and in which the oil scraper ring can play roles as an oil ring and an oil scraper to prevent excessive oil consumption. The present invention includes an oil scraper ring provided to a ring groove formed below the compression ring, wherein upper and lower protrusions provided to an outer circumference of the oil scraper ring to be brought into contact with an inner circumference of a cylinder and wherein the upper and lower protrusions built in one body have no perforated hole in-between to provide a scraper function and an oil ring function simultaneously.

Abstract: Disclosed herein is a method for joining dissimilar metals without a need for a separate welding process. The method comprises applying a flux on a metal to be joined, inserting the metal into a mold, and injecting a molten metal into the mold. Thus, the base metal to be cast and the different metal are joined simultaneously with a casting process.