Abstract: The present invention relates to a method for estimating a distance between nodes by using a round trip time (RTT) of a packet based on a CSMA/CA protocol in wireless sensor networks and a system thereof. The present invention provides a method for estimating a distance between nodes in wireless sensor networks that includes (a) measuring a transmission time of a transmission signal transmitted to the other node and a reception time of a reception signal received from the other node in response the transmission signal, and receiving a reception time of the transmission signal through the reception signal from the other node and a transmission time of the reception signal through a signal received after the reception signal from the other node; and (b) estimating a distance to the other node by using the transmission/reception time of all signals acquired in step (a).

Abstract: An electrolytic sterilizing apparatus comprises an electrolytic module (10) including an inlet port (11-1) disposed at one end thereof for allowing ballast water (40) to be introduced therethrough, an outlet port (11-2) disposed at the other end thereof for allowing the ballast water (40) to be discharged therethrough, a baffle unit (20) mounted at the inlet port (11-1) side for generating eddy flow, a sensor (30) mounted at the outlet port (11-2) side for measuring residual chlorine concentration, and a chamber (11) disposed between the baffle unit (20) and the sensor (30), the chamber (11) having electrode sets (12-1) mounted therein, each of the electrode sets (12-1) including a pair of electrodes (12), a power supply unit (50) for supplying power to the electrolytic module (10), and a connecting unit (60) including a pump (61) for introducing and discharging the ballast water (40), a pipe (62) connected to the pump (61), and a valve (63).

Abstract: Disclosed herein is a method of calibrating a robot. The robot has a robot arm with a mechanically restricted moving displacement. In the robot calibration method of the present invention, a first moving displacement between a normal position of the robot arm and a contact position, where the robot arm comes into contact with the body of the robot, is obtained. A second moving displacement between a current position of the robot arm and the contact position is obtained by moving the robot arm to the contact position. The current position of the robot arm is corrected to the normal position on the basis of a difference between the first and second moving displacements.

Abstract: A method of calibrating a robot having a robot arm with a mechanically restricted moving displacement, includes obtaining a first moving displacement between a normal position of the robot arm and a contact position in which the robot arm comes into contact with the body of the robot. A second moving displacement between a current position of the robot arm and the contact position is further obtained by moving the robot arm to the contact position. The current position of the robot arm is corrected to the normal position based on a difference between the first and second moving displacements.