1. All of the plaintiffs' claims are dismissed.

2. The costs of lawsuit are assessed against the plaintiffs.

1. Basic facts

A. The party relations 1) The defendant is a public corporation established pursuant to the Local Public Enterprises Act and the Seoul Metropolitan Government Ordinance on the Establishment and Operation of the Seoul Metropolitan Government, which aims to build and operate subway 1 through 4 lines, and the non-party Seoul Urban Railroad Workers' Union is the defendant's trade union (hereinafter "non-party trade union").

(2) As the Defendant’s 1955 employee, the Plaintiffs were dismissed on December 31, 2014 on the premise that the retirement age was 59 years of age as follows.

B. 1) The Defendant’s employees’ retirement age was originally 60 years of age, but around December 200, the retirement age was reduced to 58 years of age through the conclusion of collective agreements and the revision of the Personnel Regulations (Article 32) between the Defendant and the Non-Party Cooperatives (Article 32). (2) The Defendant and the Non-Party Partnership agreed to the principle that “the retirement age is extended to and linked with the extension of the retirement age of the next public officials,” on several occasions during the process of concluding collective agreements in 2003 on December 31, 2003, collective agreements in the collective agreement in the year 2007, January 307, 2007, and November 208, 2008, as the Local Public Officials Act was amended in the order of June 13, 2008 and December 31, 2008.

However, there was no change in the content of the provision regarding the extension of retirement age under the collective agreement concluded on December 22, 2010 between the Defendant and the Nonparty Cooperative, as well as the provision regarding the extension of retirement age for public officials in the future.

3) Meanwhile, since 2011, discussions have been made on the issue of extending the retirement age of the Defendant’s employees. The Defendant and the non-party partnership reached the labor-management agreement on the issue of extending the retirement age on December 10, 2012. The relevant details among them are as follows (hereinafter “the provisions for extending the retirement age in 2012”).

1. The extension of retirement age and retirement allowances are as follows: (a) The extension of retirement age shall enter into force as a public official; (b) the extension of retirement age and the reduction of retirement allowances (including retirement allowances):