Abstract: The present invention relates to: an underwater tunnel construction method for constructing an underwater tunnel by successively coupling new tunnel modules to the end of an already-constructed body part while moving a launching girder forward, wherein the new tunnel modules are sunk up to the opening of the launching girder and then introduced into the launching girder by using guide cables; and an underwater tunnel constructed by the construction method.

Abstract: The present disclosure relates to: a flexible joint connecting device used for sequentially coupling precast concrete segments so as to construct an underwater tunnel; an underwater tunnel construction method using the flexible joint connecting device so as to join, in a watertight manner, tunnel modules and integrally connect same, thereby constructing the underwater tunnel; and the underwater tunnel constructed by the construction method.

Abstract: The present disclosure relates to: a flexible joint connecting device used for sequentially coupling precast concrete segments so as to construct an underwater tunnel; an underwater tunnel construction method using the flexible joint connecting device so as to join, in a watertight manner, tunnel modules and integrally connect same, thereby constructing the underwater tunnel; and the underwater tunnel constructed by the construction method.

Abstract: An engagement guarantee system uses a gamification method and includes a sensor configured to sense vehicle data from a vehicle tag attached to a vehicle, to sense tool data from a tool tag attached to a tool, and to transmit the sensed data to a server A controller is configured to receive the vehicle data and the tool data from the server, to transmit an engagement torque corresponding to the vehicle to the tool, and to receive an engagement result from the tool An analyzer is configured to receive the engagement result from the controller, to analyze the engagement result, and to transmit an analyzed result to a display unit. The display unit is configured to display the analyzed result transmitted from the analyzer.

Abstract: An engagement guarantee system uses a gamification method and includes a sensor configured to sense vehicle data from a vehicle tag attached to a vehicle, to sense tool data from a tool tag attached to a tool, and to transmit the sensed data to a server A controller is configured to receive the vehicle data and the tool data from the server, to transmit an engagement torque corresponding to the vehicle to the tool, and to receive an engagement result from the tool An analyzer is configured to receive the engagement result from the controller, to analyze the engagement result, and to transmit an analyzed result to a display unit. The display unit is configured to display the analyzed result transmitted from the analyzer.

Abstract: Two types of HgO-modified electrodes are disclosed. The HgO-modified electrode according to the present invention comprises, HgO particles as precursor of mercury, which can be exposed on the surface of the said electrode and then can be reduced electrochemically into micro-droplets of mercury; and electro-conductive material to maintain optimal conductivity of the said modified electrode. In the HgO-modified electrode according to the present invention, built-in mercury precursor, HgO can be utilized feasibly for the generation of the surface mercury droplets by in situ electrochemical treatment or pretreatment without necessity of Hg.sup.2+ solution. The electrode surface can be renewed easily either by a simple polishing process for the bulk-modified electrode type-I or by simple exchange for the screen-printed disposable type modified electrode type-II. So further simplification of anodic stripping analysis process is possible by employing the HgO-modified electrodes according to the present invention.