1. The plaintiff (Counterclaim defendant)'s main claim is dismissed.

2. The Plaintiff (Counterclaim Defendant) is KRW 12,437,535,00 to the Defendant (Counterclaim Plaintiff).

(b) the facts that are common to the principal lawsuit and the counterclaim.

A. The Plaintiff is a company engaged in manufacturing industrial machinery and parts, and metal equipment and parts processing business, etc., and the Defendant is a person engaged in heat processing business with the trade name “B”.

나. 원고는 2013. 6.경 피고에게 스텝 라이너(STEP LINER, 규격 268*1020*2780, 무게 4,300kg , 이하 ‘이 사건 철강판’이라 한다) 1개에 대한 열처리 가공을 의뢰하면서, 피고와 사이에 이 사건 철강판에 대한 열처리 가공대금을 2,365,000원(부가가치세 포함)으로, 열처리 가공에 따른 이 사건 철강판의 표면경도 수치를 HS 55~65로 정하여 열처리 가공약정(이하 ‘이 사건 열처리 가공약정’이라 한다)을 체결하였다.

C. Around August 8, 2013, the Defendant completed heat processing work for the steel of this case and attached a report on heat processing with the surface longitude value stated in HS 63-64.

8. Around 12.1, the Defendant supplied the steel board of this case to the Defendant.

[Ground of recognition] The fact that there is no dispute, Gap's No. 1, 7, Gap's No. 4-2, 7, Eul's evidence No. 2, and the purport of the whole pleadings

2. Determination on the main claim

A. The plaintiff asserted 1) The plaintiff alleged that the defendant erred in processing heat of the steel of this case, thereby making it impossible to use the steel board any more than HS 55-65 because the surface diameter value of the steel board was below HS 55-65. The plaintiff asserted that the defendant suffered damage of the material cost of KRW 16 million, reprocessing cost of KRW 15 million, and KRW 34.5 million due to the defendant's nonperformance of obligation, and claimed payment of the above damages against the defendant. 2) The defendant alleged that the defect of the steel board of this case was due to the plaintiff's fault in processing heat of the steel of this case, not due to the defendant's fault in processing heat of the steel of this case, but due to the plaintiff's fault in cutting. Thus, the plaintiff's claim is unjust.

B. Each evidence mentioned above and the result of this court’s entrustment of appraisal to appraiser C.