The appeal is dismissed.

The costs of appeal are assessed against the Plaintiff.

The grounds of appeal are examined.

1. In a case where a contractual content is written between the contracting parties in writing, which is a disposal document, if the objective meaning of the text is clear, barring special circumstances, the existence and content of the expression of intent shall be recognized as well. However, where the objective meaning of the text is not clearly revealed, it shall be reasonably interpreted in accordance with logical and empirical rules so that it conforms to the ideology of social justice and equity, by comprehensively taking into account the contents of the text, the motive and background leading up to the agreement, the purpose to be achieved by

(1) Article 20 of the Civil Procedure Act provides that “The court shall render a judgment as to whether the allegation is true in accordance with logical and empirical rules based on the ideology of social justice and equity by taking into account the purport of the entire pleadings and the result of the examination of evidence (see, e.g., Supreme Court Decisions 93Da3103, Oct. 26, 1993; 2002Da6753, Jun. 11, 2002).”

(Article 432 of the same Act). 2. The lower court determined to the following purport on the grounds stated in its reasoning.

(1) At the time of the conclusion of the instant contract, the Plaintiff, as a supplier, did not choose the method of product adjustment but selected the index adjustment method and decided to adjust the contract amount. The Plaintiff did not specify in the contract the specific index to be applied thereto.

(2) There is no dispute as to the application of the import price index surveyed and published by the Bank of Korea to the above contract price adjustment. The import price index surveyed and published by the Bank of Korea is classified into “import price index (basic classification)” and “agricultural, forestry and fishery products, mining products, and industrial products.”