1. The defendant's KRW 1,485,452,350 and its amount among the plaintiff

A. From September 19, 2014 to March 18, 2016, for KRW 1,105,910,000.

1. Circumstances leading to the dispute of this case;

A. 1) The Korea Gas Corporation contracted the Plaintiff with the construction work of the main pipe Nos. 1 from the Ulsan to the ero-speed pipelines. The Plaintiff signed a contract on July 5, 2010 with A Co., Ltd. (hereinafter “A”).

B from among the construction works of the first section of the PPP 1 main pipes from winter up to wintering (hereinafter “instant construction works”).

(1) The contract amount was determined and subcontracted from July 5, 2010 to December 31, 2013 (hereinafter “instant contract for construction”) as KRW 12,427,80,000 for the contract amount, and the construction period was determined and subcontracted as from December 5, 2010 for the construction period.

(2) After that, the Plaintiff and A had modified the instant construction contract four times, and finally changed the contract amount to KRW 11,383,350,000 on March 14, 2012.

B. On March 14, 2012, A issued an advance payment guarantee certificate with the Defendant and the instant construction contract: (a) the guaranteed amount was KRW 1,045,629,863; (b) the guarantee period was from March 14, 2012 to December 31, 2012; and (c) the guarantee creditor was determined as the Plaintiff and entered into an advance payment guarantee agreement.

On March 14, 2012, the Plaintiff received advance payment of KRW 990,00,000 from A, while paying advance payment of KRW 990,000.

C. On February 3, 2012, A issued a contract performance guarantee certificate with the Defendant and the instant construction contract: (a) the guaranteed amount was KRW 1,116,542,350 for the instant construction contract; (b) the guarantee period was from July 5, 2010 to December 31, 2013; and (c) the guarantee creditor entered into a contract for performance guarantee with the Plaintiff.

A issued a contract guarantee with the same content as the Defendant and issued it to the Plaintiff.

1) From June 2012, A does not pay equipment costs and wages due to business aggravation. On August 31, 2012, A suspended the instant construction project. The Plaintiff requested several times to resume the construction project due to concerns over delay in the construction. However, on September 25, 2012, A submitted a written statement that he/she waived the instant construction project for business reason. 2) Accordingly, the Plaintiff terminated the instant construction contract to A on September 28, 2012.