Korean businessman Tongsun Park went into D.C. Superior Court yesterday to fight for his interest in the corporation which manages the Pisces Club, a private Georgetown club.

Park, who has acknowledged that he gave more than $850,000 in cash payments to United States congressmen in connection with efforts by Korea to insure continued U.S. support, testified yesterday that his 66 shares in the 3040 M Street Corporation were sold in 1977 to Robert Viner without his consent.

Viner's attorney, Thomas C. Green, produced a November 14, 1977, letter during the trial yesterday in which Park's London secretary, S. Dane, asserted that he was forwarding Park's signed stock certificate assigning his stock to Viner, a local businessman who has had several business dealings with Park, including one in which they imported backgammon sets from Korea.

Park testified yesterday that confusion as to whether he sold his controlling interest in the corporation was caused by Francis Rosenbaum, whom Park described as a "dear friend" who moved ahead to sell Park's interest in the corporation without Park's authority.

"Mr. Rosenbaum was considered more or less as a messenger between Mr. Viner and myself," Park said. "I have never indicated to anyone that Mr. Rosenbaum had the authority to represent me in a business transaction."

Park, who is scheduled to testify in a federal bribery trial in New Orleans next week, said yesterday that his 66 shares of 3040 M Street stock are worth $33,000. In addition, Park said he is attempting to protect a $500,000 investment in 3040 M Street made over the last five years by another of his firms, Pacific Development Inc.