1. The defendant's appeal is dismissed.

2. Of the appeal costs, the part arising between the Plaintiff and the Defendant is the Defendant.

1. Basic facts

A. On April 4, 2008, the Plaintiff was awarded a subcontract for construction works of art galleries located in a park from the Posi-dong 384 and 262 lots of land from the Posi-si to the Posi-dong 384 and the 262 lots of land from the Posi-si to the Posi-si. 2) on April 4, 2008 with respect to the interior, water supply, and natural materials supply (hereinafter “the instant construction works”) from the Plaintiff during the said construction works (hereinafter “the instant construction works”), with the amount of construction cost of KRW 715,00,000,000 and the period of construction from May 1, 2008 to September 30, 2008.

(3) Since the conclusion of the instant subcontract, Tech did not commence construction works due to design changes and delay in construction works. On October 2009, most of the remaining construction works were completed, the instant subcontract commenced around that time. (b) The Defendant and Museum entered into a guarantee insurance contract with respect to the instant subcontract, with the content that the insured is the Plaintiff, the instant subcontract, the contract amount of which is KRW 715,00,000,000, and each guarantee insurance contract with respect to the remaining matters (hereinafter referred to as the “each of the instant guarantees insurance contracts”), and the Defendant’s Intervenor jointly and severally guaranteed obligations, such as reimbursement of damages, against the Defendant of Tex under the instant advance payment contract (hereinafter referred to as the “instant advance payment guarantee contract”) on October 27, 2009.

A contract deposit under the supply contract of April 30, 208 (amended by November 30, 2009) under the supply contract of which the contents of the main contract to guarantee the insurance amount are fulfilled on April 7, 2008 (contract) and the contents of the main contract to guarantee the insurance amount are 71,50,000 won on April 4, 2008; - May 1, 2008 - September 30, 2008 (amended by November 30, 2009 after 200,000 won on April 15, 2008).