Abstract: A method of operating the semiconductor device includes performing an erase operation on a plurality of memory cells, performing a back-tunneling operation by injecting electrons into a storage node from a gate electrode of a memory cell, selected among the plurality of memory cells, and performing a program operation by injecting electrons into the storage node from a channel layer of the selected memory cell.

Abstract: An optical fiber unit for air blown installation includes at least one optical fiber having a core layer and a clad layer, a protective layer coated on the surface of the optical fiber; and protrusions made of polymer resin and formed on the outer circumference of the protective layer in a banded shape. The protrusions may be formed either by supplying polymer resin to the outer circumference of the optical fiber with passing the optical fiber through an extrusion dice in which grooves of a predetermined shape are formed on a hollow inner circumference thereof, or by supplying polymer resin to the outer circumference of the optical fiber through nozzles with moving the optical fiber in a longitudinal direction.

Abstract: An Outside Vapor Deposition (OVD) apparatus for making an optical fiber preform with uniform deposition of silica particles through uniform heating to the overall length of the preform includes a mandrel having a predetermined length and driven to rotate and a burner for emitting a combustion gas together with a combustion gas toward the mandrel and burning the combustion gas to make silica particles to that the silica particles are deposited on a surface of the mandrel, wherein the burner has a length corresponding to the length of the mandrel and provides uniform temperature throughout the overall length of the mandrel at the same time.

Abstract: An optical fiber unit installation apparatus having a unit for preventing a fluid from flowing backward toward entrance of the optical unit to prevent fluid leakage while the optical fiber unit is installed using air pressure is disclosed. The apparatus includes an optical fiber unit supplier; a blowing head having an entrance for introduction of an optical fiber unit supplied from the supplier, and an exit communicated with the entrance and combined with a tube for air pressure installation; a pressing unit for applying air pressure to the optical fiber unit introduced into the blowing head to insert the optical fiber unit into the tube; and a fiber sealing unit, an aggregation of fur-type elastic fibers, mounted in an advancing path of the optical fiber unit through the blowing head to prevent fluid leakage by surrounding the optical fiber unit with fiber ends contacted thereon.

Abstract: Disclosed is a tube for installing an optical fiber unit having lubricous surface, which is installed in a communication pipe. The tube for installation includes an inner layer having lubricant components to decrease friction against an optical fiber unit, and an outer layer provided around the inner layer and composed of polymer having a lower friction coefficient than polyethylene so as to decrease friction when the tube is installed in the communication pipe. The tube is easier to install than the conventional one due to decreased friction against the communication pipe.

Abstract: An optical fiber unit installation apparatus having a unit for preventing a fluid from flowing backward toward entrance of the optical unit to prevent fluid leakage while the optical fiber unit is installed using air pressure is disclosed. The apparatus includes an optical fiber unit supplier; a blowing head having an entrance for introduction of an optical fiber unit supplied from the supplier, and an exit communicated with the entrance and combined with a tube for air pressure installation; a pressing unit for applying air pressure to the optical fiber unit introduced into the blowing head to insert the optical fiber unit into the tube; and a fiber sealing unit, an aggregation of fur-type elastic fibers, mounted in an advancing path of the optical fiber unit through the blowing head to prevent fluid leakage by surrounding the optical fiber unit with fiber ends contacted thereon.

Abstract: Method and apparatus for installing an optical fiber unit capable of removing static electricity existing between the optical fiber unit and an installation tube, by using gas flow. In the method and apparatus, ions are included in a gas for installing the optical fiber unit so as to neutralizing and remove the static electricity generated during installation. The ions included in the installation gas may be obtained by disposing an ion generator at a front or rear end of a pressing means which compresses the installation gas.

Abstract: An optical fiber unit for air blown installation includes at least one optical fiber having a core layer and a clad layer, a protective layer coated on the surface of the optical fiber; and protrusions made of polymer resin and formed on the outer circumference of the protective layer in a banded shape. The protrusions may be formed either by supplying polymer resin to the outer circumference of the optical fiber with passing the optical fiber through an extrusion dice in which grooves of a predetermined shape are formed on a hollow inner circumference thereof, or by supplying polymer resin to the outer circumference of the optical fiber through nozzles with moving the optical fiber in a longitudinal direction.

Abstract: A method of applying spin to a coated optical fiber to be rotated on its longitudinal axis so that the optical fiber has an ultra-low PMD (Polarization Mode Dispersion) includes the steps of: guiding the coated optical fiber so as not to be deviated from a certain range off a drawing axis at a lower end of an optical fiber coating point; giving torque to the optical fiber by contacting the coated optical fiber with a driving roller which vibrates on the center of an axis substantially parallel to a drawing direction at a lower end of the guiding point; and adjusting an amplitude (A) of the driving roller and a distance (l) between the guiding point and the vibrating point so as to control an angle (?) between the vibrating optical and the drawing axis. This makes it possible to control a spin rate (spins/m) of the optical fiber generated by rotation.

Abstract: A method for making an optical fiber preform having an ultimately low PMD (Polarization Mode Dispersion) through improvement of ovality is provided. This method has several collapse steps for collapsing an optical fiber preform having a clad/core deposition layer formed in a preform tube in which a rate of collapse is 0.01-0.06 mm/min at each collapsing step. By using this method, ovality and PMD of the optical fiber preform may be improved.

Abstract: Disclosed are method and apparatus for fabricating an optical fiber preform in OVD (Outside Vapor Deposition) by depositing soot particles, generated by reaction of gas emitted from a burner, on a surface of a rotating mandrel. In the method and apparatus, it is controlled so that deposition concentration of the soot particles deposited on the preform is kept constant regardless of a radius of the preform or gradually increasing outward by keeping constant or gradually decreasing a trajectory velocity of a certain time on the surface of the rotating preform while depositing the soot particles.

Abstract: An Outside Vapor Deposition (OVD) apparatus for making an optical fiber perform with uniform deposition of silica particles through uniform heating to the overall length of the preform includes a mandrel having a predetermined length and driven to rotate and a burner for emitting a combustion gas toward the mandrel and burning the combustion gas to make silica particles to that the silica particles are deposited on a surface of the mandrel, wherein the burner has a length corresponding to the length of the mandrel and provides uniform temperature throughout the overall length of the mandrel at the same time.