Abstract: A method of fabricating a silicon wafer, which includes the steps of preparing a silicon wafer by slicing, grinding, and cleaning an ingot, inserting the silicon wafer in a diffusion furnace having an ambience of one of Ar, N2 and inert gas including Ar and N2, pre-heating and maintaining the diffusion furnace at about 500° C., changing the ambience into one of H2, Ar and inert gas including H2 and Ar successively, increasing a temperature of the diffusion furnace by a temperature-increasing speed of 50˜70° C./min between 500˜800° C., 10˜50° C./min between 800˜900° C., 0.5˜10° C./min between 900˜1000° C., and 0.1˜0.5° C./min between 1000˜1250° C., maintaining the diffusion furnace at 1200˜1250° C.

Abstract: A method of fabricating a silicon wafer, which includes the steps of preparing a silicon wafer by slicing, grinding, and cleaning an ingot, inserting the silicon wafer in a diffusion furnace having an ambience of one of Ar, N2 and inert gas including Ar and N2, pre-heating and maintaining the diffusion furnace at about 500° C., changing the ambience into one of H2, Ar and inert gas including H2 and Ar successively, increasing a temperature of the diffusion furnace by a temperature-increasing speed of 50˜70 ° C./min between 500˜800° C., 10˜50° C./min between 800˜900° C., 0.5˜10 ° C./min between 900˜1000° C., and 0.1˜0.5° C./min between 1000˜1250° C., maintaining the diffusion furnace at 1200˜1250° C.

Abstract: The vacuum insulator in accordance with the present invention comprises glass white wool body which density is 0.1˜0.5 g/cm3 in density and is below 0.0023 kcal/mh° C. in thermal conductivity, and a non permeable container surrounding the body in which the pressure is between 10−6 ˜10−1 torr. The vacuum insulator is fabricated by piling up glass white wool, thermal-pressutizing the piled glass white wool to form a body of 0.1˜0.5 g/cm3 in density wherein the pressurizing is done at 0.007˜1.5 kg/cm2 and under 20° C. for more than 10 minutes, putting the body in the non-permeable container, and producing a vacuum in the container.

Abstract: A method for filament winding a pressure vessel having at both end domes thereof holes of different diameters and preferably used for a high pressure combustor of a rocket engine. The present method comprises first and second winding processes. In the first process, the first mandrel on which the winding band is wound is provided with a jig which makes the outer diameters of the opposite bosses of the mandrel be equal to each other and is removed after hardening process. In the second process, the winding band is again wound on the second mandrel comprising a first body obtained from the first process and provided with a jig which makes the outer diameters of the opposite bosses of the second mandrel be equal to each other and is removed after hardening process.