1. The plaintiff's appeal is dismissed.

2. The costs of appeal shall be borne by the Plaintiff, including the part arising from the supplementary participation.

The reasoning of the court of first instance is as stated in the reasoning of the judgment in the judgment of the court of first instance, in addition to using some parts as follows. As such, Article 8(2) of the Administrative Litigation Act and Article 420 of the Civil Procedure Act shall be cited. On the other hand, the part to be used is as follows: “(2) whether the retirement age provision in this case is valid” (from 10th to 13th 20th 10th 10th 10th 10th 10th 10th 10th 10th 20th 20th 20th 20th 200). The supplementary provision in this case provides that “The supplementary agreement may be concluded even during the effective period of this agreement with respect to matters which are to be modified by changing social or economic conditions or by amending laws, etc., and the supplementary agreement shall have the same effect as this Convention, and thus, the said collective agreement shall be concluded with an employer and workers’ labor union may not be acknowledged for the purpose of improving their economic conditions and collective agreement terms and conditions.”

(see Supreme Court Decision 201Da86287, Feb. 13, 2014). The Trade Union and Labor Relations Adjustment Act (hereinafter “Trade Union and Labor Relations Adjustment Act”) adopts the system of simplification of bargaining windows, thereby prescribing the Trade Union and Labor Relations Adjustment Act.