Abstract: A grinding wheel includes a plurality of wheel tips. The plurality of wheel tips include a plurality of diamond abrasive grains and a bonding material mixed with the diamond abrasive grains. The plurality of diamond abrasive grains have a ratio of a length in a long axis direction to a width in a short axis direction of 1:2.5 to 1:3.5 and includes edges or vertices having a grinding angle of 90° or less.

Abstract: A washing machine including a washing tub to allow enhancement in washing efficiency. A washing tub of the washing machine includes a pattern having a protrusion portion to generate friction force between laundry and the washing tub and to thereby increase washing efficiency. The pattern has a concave-convex structure and performs action similar to a lifter, washing efficiency may be enhanced using tumbling generated by the pattern. A plurality of drain holes are arranged in a certain pattern in the washing tub to prevent a dehydration bottleneck phenomenon in which dehydration is concentrated at a particular drain hole and to increase a dehydration rate. The pattern is provided such that protrusion portions and recessed portions continue on the surface of the washing tub to enhance stiffness of the washing tub.

Abstract: A washing machine including a washing tub to allow enhancement in washing efficiency. A washing tub of the washing machine includes a pattern having a protrusion portion to generate friction force between laundry and the washing tub and to thereby increase washing efficiency. The pattern has a concave-convex structure and performs action similar to a lifter, washing efficiency may be enhanced using tumbling generated by the pattern. A plurality of drain holes are arranged in a certain pattern in the washing tub to prevent a dehydration bottleneck phenomenon in which dehydration is concentrated at a particular drain hole and to increase a dehydration rate. The pattern is provided such that protrusion portions and recessed portions continue on the surface of the washing tub to enhance stiffness of the washing tub.

Abstract: A washing machine including a drum capable of improving washing efficiency is provided. The washing machine includes a body, a tub provided at an inside the body to store wash water, a drum rotatably provided at an inner side of the tub to accommodate laundry, a driving apparatus to rotate the drum, protrusions that are formed of polygons having polygonal shapes and protruding inward from the drum, and a through-hole provided between adjacent protrusions to drain water. A protrusion having polygons generates frictional force between laundry and the drum, thereby increasing the washing power. The through-holes are uniformly located around the protrusion, thereby preventing a spin dry water bottleneck phenomenon that occurs when water from a spin dry is concentrated on a certain through-hole, and thus enhancing the spin dry efficiency.