All appeals are dismissed.

The costs of appeal are assessed against the plaintiffs.

The grounds of appeal are examined.

1. As to the grounds of appeal No. 1, the lower court dismissed the Plaintiffs’ claim for return of unjust enrichment on the ground that there is insufficient evidence to support that the amount paid by Plaintiffs B, C, and G was used as the construction cost of the instant apartment.

Examining the record, the above determination by the court below is justifiable.

There is no error of exceeding the bounds of the principle of free evaluation of evidence against logical and empirical rules or misapprehending the legal principles on unjust enrichment without exhausting all necessary deliberations.

(2) As to the grounds of appeal Nos. 2 and 4, the lower court, on the grounds as indicated in its reasoning, determined that there is insufficient evidence to support the completion of subcontracted construction works by Austria Co., Ltd. (hereinafter “I”), and that Plaintiff F did not fully bear the burden of proving the scope of construction works and construction costs performed by Austria Co., Ltd., and dismissed Plaintiff F’s claim.

Examining the record, the above determination by the court below is justifiable.

In doing so, there is no error of exceeding the bounds of the principle of free evaluation of evidence against logical and empirical rules, or by misapprehending the legal principles on the principle of pleading.

(3) As to the ground of appeal No. 3, ratification of invalidation or unauthorized representation is a single act with knowledge of the invalidation and the effect of such an act on his/her own, and it does not require a certain method as to the method of expression of intent. Thus, in order to recognize implied ratification, there should be circumstances to deem that the person himself/herself has fully understood the legal status faced by such act and, even if so, it should be recognized that the result of such act belongs to himself/herself.

Supreme Court Decision 201No. 13.