Abstract: Provided are a silicon nitride film etching composition, a method of etching a silicon nitride film using the same, and a manufacturing method of a semiconductor device. Specifically, a silicon nitride film may be stably etched with a high selection ratio relative to a silicon oxide film, and when the composition is applied to an etching process at a high temperature and a semiconductor manufacturing process, not only no precipitate occurs but also anomalous growth in which the thickness of the silicon oxide film is rather increased does not occur, thereby minimizing defects and reliability reduction.

Abstract: According to the disclosure, a position of a main control valve and a position of an auxiliary control valve are adjusted. In particular, a position of the auxiliary control valve is adjusted by determining whether a change in the position of the main control valve is in a preset deadband range, thereby preventing a periodic water level fluctuation of a steam generator.

Abstract: Provided are a method and system for improving control of a steam generator level for preventing oscillation of the steam generator level in a nuclear power plant. In order to prevent oscillation of a steam generator level and resultant shutdown of a nuclear reactor, which may be caused when a high-level priority control function is frequently and repeatedly turned on/off as the steam generator level is excessively increased, by improving a feedwater control system in the nuclear power plant, a proportional integral control value may be controlled to be reduced, and thus, output while a certain condition is met after a high-level priority mode is deactivated or a signal instructing to enter the high-level priority control mode may be controlled not to be output.

Abstract: Provided are a method and system for improving control of a steam generator level for preventing oscillation of the steam generator level in a nuclear power plant. In order to prevent oscillation of a steam generator level and resultant shutdown of a nuclear reactor, which may be caused when a high-level priority control function is frequently and repeatedly turned on/off as the steam generator level is excessively increased, by improving a feedwater control system in the nuclear power plant, a proportional integral control value may be controlled to be reduced, and thus, output while a certain condition is met after a high-level priority mode is deactivated or a signal instructing to enter the high-level priority control mode may be controlled not to be output.

Abstract: A system and a method of transforming a gain and an integral time constant of a proportional-integral (PI) controller according to a timer lapse time to relieve an excessive phenomenon of a steam generator level caused by rapid changes in open degrees of a downcomer feed-water valve and an economizer feed-water valve when reactor power transfers between low and high power sections. Accordingly, an excessive phenomenon of a steam generator level is relieved at a transfer time when reactor power transfers between low and high power sections. Therefore, a possibility of a stop of a reactor caused by the excessive phenomenon of the steam generator level is reduced to relieve burden on an operator and improve an operation rate and economic feasibility of a nuclear power plant.

Abstract: Provided is an apparatus for controlling a gain according to a water level change rate of a steam generator in nuclear power plants.

Abstract: An apparatus for controlling an output of a pressure setting signal to automatically control a steam bypass control system includes a pressure setting signal output unit for outputting a pressure setting signal according to a cold leg temperature of a reactor coolant; a first logic value output unit for outputting a first logic value that is changed according to reactor power; a second logic value output unit for outputting a second logic value that is changed according to a temperature difference between an average temperature of the reactor coolant and a reference temperature; a NAND gate circuit unit for outputting an inverse logic value according to the first and second logic values; and a first output control unit for controlling whether to output the pressure setting signal according to the inverse logic value of the NAND gate circuit unit.

Abstract: Disclosed herein is a method of manufacturing a door frame for a wind tower. The method includes a first step of forging a circular planar substance, thereby forming a through hole in a central portion of the substance, a second step of heating the substance that was processed in the first step, a third step of ring-rolling the heated substance around the through hole in an annular shape such that a circumstance of a center hole of the substance is equal to a length of a center line of the door frame, a fourth step of upset-forging the annular substance so that opposite sides of the substance are pressed to form linear sections, and a fifth step of fine-finishing the substance that was processed by the fourth step, thus completing the door frame.

Abstract: A system and a method of transforming a gain and an integral time constant of a proportional-integral (PI) controller according to a timer lapse time to relieve an excessive phenomenon of a steam generator level caused by rapid changes in open degrees of a downcomer feed-water valve and an economizer feed-water valve when reactor power transfers between low and high power sections. Accordingly, an excessive phenomenon of a steam generator level is relieved at a transfer time when reactor power transfers between low and high power sections. Therefore, a possibility of a stop of a reactor caused by the excessive phenomenon of the steam generator level is reduced to relieve burden on an operator and improve an operation rate and economic feasibility of a nuclear power plant.

Abstract: Provided are a method and apparatus for validating dynamic performance of a control system of a nuclear power plant in operation, without performing a power ascension test. According to the present invention, when the performance of the control system requires to be validated in order to change a control logic or its setpoint of or to replace hardware of the control system, the dynamic performance of the control system may be validated without performing the power ascension test which can be performed only in a trial operation and requires large expenses. In the present invention, a design computer code capable of simulating a transient state of the nuclear power plant is connected to the hardware of the control system, and tests to be performed at the power ascension test or in the transient state of the nuclear power plant are simulated by directly using the hardware of the control system instead of a control system model of the design computer code, in an on-line state.

Abstract: An interpenetration apparatus for the measurement of a magnitude of a blasting vibration comprises a housing including a fixture and a mover divided into two, symmetrically, in a longitudinal direction, in which the fixture includes a space for receiving a cable and the mover includes at least two grooves perforated to receive sensors, respectively; a head portion for fixing the front end of coupled fixture and mover to prevent the escape of the mover from the fixture; a handle including a fixing rod threadedly coupled to the rear portion of the fixture; a connecting rod connected to the fixing rod and extended in a predetermined length therefrom to insert the interpenetration apparatus into a working hole perforated adjacent to an approach to a tunnel; and a traction tool connected to the rear end of the mover to operate the mover, thereby enabling the housing to be at the nearest position from the blasting place, and sensitively detecting the wave motion of the blasting vibration as well as three dimensiona