Abstract: Disclosed is a hot air welder that consecutively joins sheets of synthetic resin material together to make a large-sized pavilion or a tent fabric, or welds and seals the seam lines of waterproof textiles or the like for waterproofing process. Instead of the conventional table-shaped body, there are provided an upright-standing drive body; hot-air welding means on an upper-side of the drive body; upper and lower drive rollers under the welding means, and wherein the welding work is performed by rotating and using alternatively the upper drive roller or the lower drive roller, according to the kind of fabrics to be welded and the work-substances. Therefore the heat welding and waterproofing process may be performed more easily for more various shaped work-substances, and that the troublesome work-substances such as sleeve or shoulder parts of waterproof clothes that have various positioned and shaped seam lines may be moved and rotated easily by the worker to be heat-welded and become waterproofed.

Abstract: Disclosed is a hot air welder that consecutively joins sheets of synthetic resin material together to make a large-sized pavilion or a tent fabric, or welds and seals the seam lines of waterproof textiles or the like for waterproofing process. Instead of the conventional table-shaped body, there are provided an upright-standing drive body; hot-air welding means on an upper-side of the drive body; upper and lower drive rollers under the welding means, and wherein the welding work is performed by rotating and using alternatively the upper drive roller or the lower drive roller, according to the kind of fabrics to be welded and the work-substances. Therefore the heat welding and waterproofing process may be performed more easily for more various shaped work-substances, and that the troublesome work-substances such as sleeve or shoulder parts of waterproof clothes that have various positioned and shaped seam lines may be moved and rotated easily by the worker to be heat-welded and become waterproofed.

Abstract: A core for use in a slot type optical cable has one or more regularly disposed slots. One or more ribbon fibers are stacked into each of the slots, each of the ribbon fibers having a plurality of optical fibers. A tensile strength member is disposed at a center of the core. Each of the slots has a convex bottom surface with a predetermined curvature so that voids between the ribbon fiber at the bottom of the stack and top of the convex bottom surface in each of the slots are formed on both sides of the convex bottom surface. The convex bottom surface is provided with curvature whose radius is equal to or less than a distance from the center of the core to edges defined by the convex bottom surface meeting the pair of side surfaces in each of the slots.