Abstract: A roaming service method for a fast and secure wireless network is provided. In an embodiment of the present invention, an AP, which an STA associates with, transmits security keys needed for roaming to neighbor APs of the AP. When the STA moves to one of the neighbor APs, a reassociation is carried out between the STA and the neighbor AP using the already provided security key. In another embodiment of the present invention, an authentication server transmits security keys needed for roaming to neighbor APs to which the STA is likely to move, so that when the STA moves to one of the neighbor APs, a reassociation is carried out between the STA and the neighbor AP using the already provided security key.

Abstract: Disclosed is a method for packaging an organic light emitting display having a reinforcing member between a first substrate and a second substrate by rolling a roll retaining a curable material on non-pixel regions of unit display panels. Organic light emitting pixel arrays are formed at a plurality of pixel regions of a first mother substrate. A frit is formed at a position of a second mother substrate corresponding to the non-pixel regions of the first mother substrate. The mother substrates are coalesced to each other and sealed by the frit. The first and second mother substrates are cut into unit display panels. The unit display panels are aligned. The curable material is coated at a side the unit display panels and cured to form the reinforcing member.

Abstract: A method to form a thick layer by screen printing and a method to form a piezoelectric actuator of an inkjet head. The method to form the thick layer including forming a guide groove in a surface to a predetermined depth, and forming the thick layer by applying a material to the surface inside the guide groove through screen printing. The method to form the piezoelectric actuator including forming an insulating layer on a top surface of a vibration plate and forming a guide groove in the top surface of the vibration plate or an insulating layer to a predetermined depth at a position corresponding to each of a plurality of pressure chambers, forming a lower electrode on the top surface of the insulating layer; forming a piezoelectric layer inside the guide groove by screen printing, and forming an upper electrode on a top surface of the piezoelectric layer.

Abstract: An organic light emitting display in which differential pressure is controlled to prevent Newton's rings from being generated and a method of fabricating the same are provided. The organic light emitting display includes a first substrate including a pixel region in which at least one organic light emitting diode (OLED) is formed and a non-pixel region, a second substrate attached to one region including the pixel region of the first substrate, and a frit provided between the non-pixel region of the first substrate and the second substrate. At least one of the first substrate and the second substrate is formed to be convex outward.

Abstract: A piezoelectric actuator of an inkjet head and a method of forming the piezoelectric actuator. The piezoelectric actuator is formed on a vibration plate to provide a driving force to each of a plurality of pressure chambers. The piezoelectric actuator includes a lower electrode formed on the vibration plate, a piezoelectric layer formed on the lower electrode at a position corresponding to each of the pressure chambers, a supporting pad formed on the lower electrode, the supporting pad contacting one end of the piezoelectric layer and extending away from the one end of the piezoelectric layer, and an upper electrode extending from a top surface of the piezoelectric layer to a top surface of the supporting pad. The upper electrode is bonded to a driving circuit above the supporting pad to receive a voltage from the driving circuit. The piezoelectric layer may have substantially the same length as the pressure chamber.

Abstract: Disclosed is a method for packaging an organic light emitting display having a reinforcing member formed between a first substrate and a second substrate by dipping non-pixel regions of unit display panels in a liquid curable material. Organic light emitting pixel arrays are formed at a plurality of pixel regions of a first mother substrate. A frit is formed at a position of the second mother substrate corresponding to non-pixel regions of the first mother substrate. The first and second mother substrates are coalesced to each other and sealed by the frit. The mother substrates are cut into unit display panels. The unit display panels are aligned. Non-pixel regions of the unit display panels are dipped in the liquid curable material and the material is cured to form the reinforcing member.

Abstract: A method of forming a piezoelectric actuator of an inkjet head formed on a vibrating plate to provide a driving power for ejecting ink to each of pressure chambers is provided. The method includes forming a lower electrode on a vibrating plate, forming a piezoelectric layer on the lower electrode to be located above each of pressure chambers, forming a protecting layer covering the lower electrode and the piezoelectric layer, exposing an upper surface of the piezoelectric layer by decreasing a thickness of the protecting layer and the piezoelectric layer, forming an upper electrode on the upper surface of the piezoelectric layer, removing the protecting layer. According to the present invention, since the piezoelectric layer having a flat upper surface is formed in uniform figure, area and thickness of the upper electrode formed thereon is uniformly controlled.

Abstract: The present invention relates to a novel fulvene compound and a preparation method thereof, and more particularly to a fulvene compound having substituted groups in the 2- and 5-positions, prepared from an unsaturated ketone having a substituted group in the ?-position and a halogen atom in the ?-position, and a preparation method thereof. The present invention also relates to a metallocene catalyst having a substituted group in the ?-position carbon of the bridge of the cyclopentadienyl group only by reaction of a fulvene compound and an anion group including the cyclopentadienyl group, and a preparation method of a polyolefin copolymer using the same.

Abstract: A semiconductor device having reduced pitting may be formed from isolation layer patterns on a semiconductor substrate defining an active region, a tunnel oxide layer on the active region, the tunnel oxide layer having a nitrified surface, a floating gate on the tunnel oxide layer, a dielectric layer on the floating gate, and a control gate on the dielectric layer.

Abstract: Disclosed is a frame structure in a high-speed wireless personal area network (WPAN) and a message transmitting method thereof which enable communications among devices existing in different piconets by using a device that provides a bridging function in the IEEE 802.15.3 WPAN. In a high-speed WPAN system which includes a parent piconet having a plurality of devices and a child piconet using time slots allocated by the devices located in the parent piconet, and a bridge device located in the child piconet, that broadcasts information about the devices of the parent piconet and information about the devices of the child piconet to the devices included in the high-speed WPAN, and operates to perform a data transfer between a first specified device in the child piconet and a second specified device in the parent piconet.

Abstract: A piezoelectric inkjet printhead includes a manifold, a chamber array including a plurality of chambers in connection with the manifold and arranged along at least one side of the manifold, a vibrating plate to cover the plurality of chambers, and a plurality of piezoelectric actuators formed on the vibrating plate to change pressures of corresponding ones of the plurality of chambers by vibrating the vibrating plate. The plurality of chambers includes a plurality of pressure chambers disposed in a center portion of the chamber array and having corresponding ink ejecting nozzles, and at least two dummy chambers, one disposed on each side of the chamber array and having corresponding dummy nozzles that do not eject ink. A plurality of trenches may be formed in the vibrating plate between each of the piezoelectric actuators.

Abstract: A piezoelectric inkjet printhead includes a fluid path forming substrate having a pressure chamber, a piezoelectric actuator formed on the fluid path forming substrate to provide a drive force to the pressure chamber to eject ink, and a damping layer formed on the piezoelectric actuator to dampen a residual vibration of the piezoelectric actuator.

Abstract: A micro device and a micro mirror employing a piezo actuator are provided. The micro mirror includes a substrate; a plate which is rotatably suspended about a rotation axis over the substrate; at least two cantilevers, each comprising a fixed end fixed to the substrate, and a free end perpendicularly crossing the rotation axis of the plate and connecting to a side of the plate, each cantilever having a piezo actuator installed on an upper surface of the cantilever; a plurality of connectors each one of which connects the free end of a corresponding one of the cantilevers to a side of the plate; and a pair of torsion springs which are connected to the plate and act as a rotational axis for the plate.

Abstract: An inkjet printhead and a method of driving the inkjet printhead include a flow channel substrate having a pressure chamber, and a piezoelectric actuator formed on the flow channel substrate to apply a driving force to the pressure chamber to eject ink. The piezoelectric actuator includes a piezoelectric layer formed on the flow channel substrate to correspond to the pressure chamber, and a plurality of common electrodes and a plurality of driving electrodes alternately arranged in a length direction of the piezoelectric layer.

Abstract: Disclosed is an organic light-emitting display device in which a substrate and an encapsulation substrate are joined by a frit and a reinforcing structure. The first substrate has a pixel region in which an organic light-emitting diode is formed, and a non-pixel region formed outside the pixel region. The second substrate is attached the first substrate by the frit. A bracket is joined with substrates by the reinforcing structure. A curable material is applied to inside the frame, moves between the first and second substrates, and then cured to form the reinforcing structure.

Abstract: Disclosed are an organic light emitting display and a fabricating method of the same, which form a bracket by at least one material selected from the group consisting of a plastic, a reinforcement plastic, or a high elastic and high molecular organic material in order to enhance an adhesive strength and an elasticity of a substrate and a bracket adhered to each other by means of an adhesive. A first substrate includes a pixel region and a non-pixel region. At least one organic light emitting diode is formed at the pixel region and having a first electrode, an organic layer, and a second electrode. The non-pixel region is formed beside pixel region. A second substrate is bonded to a first side of the first substrate to seal the pixel region. A frit is disposed between the non-pixel region of the first substrate and the second substrate and adheres the first and second substrates to each other.

Abstract: Provided are a bimetallic zinc complex and a method of producing polycarbonate, including polymerizing an epoxy compound and carbon dioxide using the bimetallic zinc complex. The bimetallic zinc complex according to the present invention has a distance between zinc-zinc atoms, which is maintained in a limited range regardless of its concentration in a reaction medium for the polymerization. Thus, the bimetallic zinc complex can have a polymerization activity even at a high ratio of monomer/catalyst, thereby reducing a catalyst amount to be used, which is economically advantageous. Further, the bimetallic zinc complex can produce a high molecular weight polycarbonate.

Abstract: A two-axis micro scanner is provided in which horizontal driving required for high frequency motion uses a vertical comb-type electrode structure and vertical driving required for low frequency motion uses a piezo-actuator. The micro scanner includes: a frame; a horizontal driving unit including a micro mirror, a plurality of vertical moving comb-electrodes formed parallel to each other along opposite sides of the micro mirror, a plurality of vertical static comb-electrodes formed to alternate with the moving comb-electrodes; and a vertical driving unit including a plurality of cantilevers extending from the frame and respectively connecting opposite ends of the horizontal driving unit to support the horizontal driving unit. A piezo-actuator is installed on an upper surface of each of the cantilevers, wherein the cantilevers are upwardly/downwardly bent according to contraction/expansion of the piezo-actuators.

Abstract: Example embodiments of the present invention relate to an alloy solder and a semiconductor device using the alloy solder. Other example embodiments relate to an alloy solder capable of increasing reliability of a junction between a semiconductor chip and a substrate. According to still other example embodiments of the present invention, there may be a tin-bismuth (Sn—Bi) family alloy solder between a semiconductor chip and a substrate, and a semiconductor device using the alloy solder. The semiconductor device may include a semiconductor chip formed with a plurality of gold (Au) bumps, a substrate having metal wirings connected to the gold (Au) bumps, and a junction including a tin-bismuth (Sn—Bi) family alloy solder interposed between and connecting the gold (Au) bump and the metal wiring.

Abstract: An LCD device and a method of fabricating the same is disclosed, which can prevent transmitting light from being mixed in adjacent pixels, the LCD device including: a plurality of etching patterns formed in an insulation substrate; a plurality of color filter patterns of red, green and blue colors formed in the respective etching patterns; a black matrix pattern formed on the insulation substrate between each of the color filter patterns; and an overcoat layer formed on an entire surface of the insulation substrate including the black matrix pattern.