The defendant is a corporation established with the purpose of contributing to the improvement of people's lives and the promotion of public welfare by facilitating the supply of water for living and improving water quality through the comprehensive development and management of water resources, and the plaintiffs are currently workers of the defendant.

The defendant paid wages according to the rules of the defendant's annual salary, etc., by enforcing the annual salary system for employees under his/her jurisdiction, monthly salary for the 21st day of each month (monthlyly paid annual salary, which is divided into the standard salary, additional salary, job pay, and treatment pay according to the results of evaluation of capacity, duties, etc. and grades), performance-based salary (in accordance with the results of evaluation of achievements, etc. by individuals and departments in the preceding year, it is divided into performance-based bonuses and benefits-based bonuses), and additional salary (an annual salary paid according to job conditions, living conditions, etc.), and paid the annual salary as 12th day of each month.

The parts concerning management evaluation of performance rates and the payment of qualification allowances among the defendant's annual salary rules and the implementation rules of annual salary regulations are as follows:

[Rules of Annual Salaries] Article 15 (Management Evaluation Incentives) (1) Management evaluation bonuses shall be paid based on basic monthly salary, based on incentives, incentives, etc. based on the results of management evaluation of public institutions.

(2) The payment rate of performance evaluation rates shall be paid after reflecting the results of evaluation of internal management performance under the Management Regulations.

(3) The basic monthly salary under paragraph (1) shall be based on December of the immediately preceding year.

Provided, That the relevant management evaluation performance rate for an employee who is not subject to management evaluation in the year of employment shall be calculated based on the basic monthly salary of the month of retirement.

(4) Detailed matters concerning the payment of piece rates shall be prescribed by detailed regulations.

[Enforcement Regulations of the Annual Salary Regulations] Article 10 (Management Evaluation Incentives) (1) Business reputation and performance rates shall be paid quarterly.