1. The Defendants are jointly and severally liable to the Plaintiff for KRW 10,091,133 as well as 5% per annum from June 1, 2014 to April 19, 2017.

1. Basic facts

A. On January 1, 2014, the Plaintiff was awarded a contract with the Defendants for remodeling/electrics, telecommunications, and fire fighting (hereinafter “instant construction”) on the D4-story building in Busan Shipping Daegu, and completed construction from that to May 2014.

B. The Defendants paid the Plaintiff the construction cost of KRW 48 million from February 13, 2014 to April 23, 2014.

[Ground of recognition] Facts without dispute, purport of whole pleading

2. The parties' assertion

A. On January 8, 2014, the Plaintiff received a contract for the instant construction work from the Defendants in the amount of KRW 35.5 million (excluding value-added tax).

On February 20, 2014, the Plaintiff agreed with the Defendants to increase the construction cost as KRW 55.8 million (excluding value-added tax). On March 30, 2014, the Plaintiff again agreed on the additional construction cost separate from the Defendants (value-added tax).

Therefore, the total construction cost is KRW 7,2490,000 and value-added tax amounting to KRW 65,90,000. Therefore, the Defendants are obligated to pay the remainder construction cost to the Plaintiff.

B. At the beginning of the Defendants, the construction amount contracted with the Plaintiff was KRW 28 million, but on January 13, 2014, the Plaintiff agreed with the Defendants to increase the construction amount to KRW 33.5 million.

However, on February 20, 2014, the Plaintiff unilaterally presented a written estimate, which increased the construction cost of KRW 55.8 million, to the Defendants. On March 30, 2014, the Plaintiff again demanded the Defendants to pay additional construction cost of KRW 10.1 million.

However, the Defendants did not have any agreement with the Plaintiff on the additional construction cost claimed by the Plaintiff, but there is a fact that they agreed to make an estimate of the Plaintiff’s construction cost calculated in the third chain E, as the instant construction cost.

E calculated the amount of the part of the construction work performed by the Plaintiff as KRW 42,724,90,09, and the Defendants paid the amount above that amount to the Plaintiff, thus there is no obligation to pay the construction cost.

3. Determination

A. First, the Plaintiff is 50 million won.