Abstract: A duct ventilation apparatus according to the present invention, which is installed in the interior of a duct, is equipped with a rotating means comprising a shaft having a plurality of blades attached on the outer circumferential surface thereof, the shaft having a length and rotating by being connected to a motor, wherein the rotating means is disposed in the inflected part of the flow space in the interior of the duct.

Abstract: Disclosed is a device for generating airflow. According to one embodiment of the present invention, the device comprises a case for dividing inner space into a couple to be faced separately side by side in the length direction, wherein an inhalation hole and an outlet hole are formed in the space, respectively, and an opening connected to the outlet hole is formed between the space, and a couple of rotation units rotatably mounted in the space and emitting outside air from the inhalation hole to the outlet hole through mutual reverse rotation by power of a motor. In this case, airflow pulling air current between the opening holes is generated by making air pressure difference between the outlet hole and inhalation hole by the emitted air through the outlet hole.

Abstract: Disclosed herein is an electric fan. The electric fan includes a casing, a rotary unit and a cover. The casing has a frame shape such that a first opening is formed in a central portion of the casing. An inlet hole and an outlet hole are respectively formed in inner and outer peripheral surfaces of the frame. A space is defined in the casing. The rotary unit includes an impeller installed in the space, and a drive unit. The rotary unit is configured such that when the impeller is rotated by the drive unit, external air is drawn into the space through the inlet hole and then discharged out of the space through an outlet hole. The cover is installed on a front part of the casing in a direct contact manner. The cover defines a second opening communicating with the first opening so that air supplied from the outlet hole is discharged out of the second opening.

Abstract: UBR traffic control apparatus and methods can control UBR bandwidth according to cell traffic state and congestion occurrence at the switch terminal. Preferred embodiments can include an egress subscriber terminal that monitors congestion of cells at the switch terminal and traffic state to generate UBR bandwidth information, and an ingress subscriber terminal that outputs UBR cells to the switch terminal according to the generated UBR bandwidth information. Preferred embodiments can increase or maximize UBR traffic by flexibly increasing, decreasing or maintaining UBR bandwidth in consideration of the cells' congestion experience at the switch terminal, the egress subscriber terminal's buffer threshold value and traffic load. By managing cell traffic state for each transmitting subscriber board and by determining subscriber boards to be controlled in consideration of the traffic state at the time of UBR bandwidth's increase or decrease, the preferred embodiments may improve the quality of UBR service.

Abstract: A traffic control apparatus for UBR service includes a first subscriber side connected to a second subscriber side through an ATM exchange. The first subscriber side includes an egress subscriber end which extracts UBR band information of the subscriber board of a second subscriber end fed back, and which determines the UBR band in accordance with the presence of cell traffic congestion and traffic loading state transmitted from the board of the second subscriber end. The apparatus further includes an ingress subscriber end which receives the UBR band information determined by the egress subscriber end, feeds back the UBR band information to the subscriber board of the second subscriber end, and processes a UBR user cell in accordance with the UBR band information of the second subscriber's board.