Abstract: A polyurethane foam which is obtained by a reaction between a diol component and a diisocyanate component, with the diol component being a mixture of a polyether-based diol and a polyester-based diol, and a pneumatic tire to which the polyurethane foam is applied are provided. When a soft polyurethane foam is produced using a mixture of a polyether-based diol and a polyester-based diol as the diol component, and by varying the content of the expanding agent during the production process, and when the polyurethane foam is disposed in the cavity of a pneumatic tire, the polyurethane foam thus produced has an effect of reducing the resonance noise generated in the cavity of the tire and improving durability of the tire.

Abstract: Disclosed are a method for manufacturing a heavy-duty pneumatic tire by winding a reinforcing belt disposed in a belt layer of a tread with an untopped spiral steel cord, and a tire manufactured by the same.

Abstract: A tread pattern of a tire is disclosed which has wave-shaped and straight grooves capable of maintaining desired block rigidity and hydroplaning performance of the tire. In the tread pattern, which includes circumferential main grooves, transversal grooves formed between adjacent ones of the circumferential main grooves, and blocks formed between adjacent ones of the transversal grooves, at least one of the circumferential main grooves has a wave-shaped structure having opposite inclined side surfaces each comprising an upper surface portion having first and second curved surfaces alternately arranged along a circumferential direction of the tire while having substantially opposite curvatures, respectively, to form a continuous wave-shaped surface, and a lower surface portion having a straight side surface connected to the alternate first and second curved surfaces while extending along the circumferential direction to form a circumferential straight groove.

Abstract: The present invention relates to a molding material for a fuel cell separator including a graphite complex having a mixture of expandable graphite and non-expandable graphite; at least one of the conductive fillers selected from the group consisting of carbon black, carbon fiber and carbon nanotube; and at least one resin selected from a thermoplastic resin and thermosetting resin. With the present invention, both the mechanical strength and electrical conductivity of the fuel cell separator can be simultaneously improved.