Abstract: A front cover for a helmet connectable to a shell for the helmet for covering an upper side, a rear side, and two sides of the head of a wearer so as to protect the upper side, the rear side, and two sides of the head of the wearer, is provided. The front cover includes a jaw protection portion configured to protect the wearer's jaw when the front cover is connected to the shell, and a jaw mediation portion connected to the jaw protection portion and configured to serve to mediate the jaw protection portion and the shell by being connected to the shell. When the jaw protection portion is connected to the shell by the jaw mediation portion, the jaw protection portion is rotatable based on the shell.

Abstract: A front cover for a helmet connectable to a shell for the helmet for covering an upper side, a rear side, and two sides of the head of a wearer so as to protect the upper side, the rear side, and two sides of the head of the wearer, is provided. The front cover includes a jaw protection portion configured to protect the wearer's jaw when the front cover is connected to the shell, and a jaw mediation portion connected to the jaw protection portion and configured to serve to mediate the jaw protection portion and the shell by being connected to the shell. When the jaw protection portion is connected to the shell by the jaw mediation portion, the jaw protection portion is rotatable based on the shell.

Abstract: A helmet according to the present invention includes: a head frame being open toward the user's face, designed to cover the user's head, and having a rotation part at both sides; a face frame coupled to be turned up and down about the rotation parts and selectively closing the opening of the head frame; and a sun visor disposed at an upper portion of the face frame and coupled to be turned up and down about the rotation parts, in which the sun visor is turned up with the face frame when the face frame is turned up to open the opening of the head frame, and is fixed regardless of rotation of the face frame when a predetermined rotational limit is reached.

Abstract: A helmet according to the present invention includes: a head frame being open toward the user's face, designed to cover the user's head, and having a rotation part at both sides; a face frame coupled to be turned up and down about the rotation parts and selectively closing the opening of the head frame; and a sun visor disposed at an upper portion of the face frame and coupled to be turned up and down about the rotation parts, in which the sun visor is turned up with the face frame when the face frame is turned up to open the opening of the head frame, and is fixed regardless of rotation of the face frame when a predetermined rotational limit is reached.

Abstract: A method for pretreating a semiconductor surface, comprising the steps of: placing a titanium nitride substrate in a reaction chamber and subjecting the reaction chamber to vacuum; purging the reaction chamber with an inert gas selected from the group consisting of N.sub.2, Ar and He and evacuating the reaction chamber into 1 mTorr or lower; treating the surface of the titanium nitride substrate with a reaction gas comprising WF; charging a reducing gas and a source gas for deposition material to form a thin film on the titanium nitride substrate, by which the nucleation rate of deposition material and the number of nucleation sites on the substrate can be increased and a thin film with a uniform thickness and high density can be formed on the substrate.