Tongsun Park, the wealthy South Korean businessman, concluded his testimony today after a tedious, week-long cross-examination in the bribery and tax evasion trial of former representative Otto E. Passman (D-La.).

The relaxed atmosphere of the courtroom turned to heated exchanges between the federal judge and the defense counsel, and frequent objections from the prosecution, in Park's last day of testimony.

Park is here as the chief prosecution witness against the former congressman.

Passman, 78, is on trial on charges of having received more than $200,000 from Tongsum Park in exchange for using his powerful chairmanship of a House Appropriations subcommittee to pressure the U.S. and Korean governments into rice sales beneficial to Park.

The government during direct examination detailed three payments central to the bribery charges -- $50,000 in April 1973, and $20,000 and $28,000 in June 1973.

Defense counsel Camille F. Gravel Jr. avoided any questions about the three payments. Instead his lengthy cross-examination, intended to impeach Park's testimony, concentrated on issues outside the scope of the indictment. Passman has denied ever receiving any money from Park.

The drawn-out questioning prompted the U.S. District Court judge for the western region of Louisiana, Earl Veron, to ask Gravel to get from the "south forty" to the "north forty." A legal motion filed by the government called for a speedy conclusion to the cross-examination and an end to "asking the same questions in virtually unaltered form five, six and seven times."

Park's testimony was interrupted twice earlier this week for the appearance of his counsel, William Hundley, and Park's past companion and Washington Hostess, Tandy Dickinson.

Dickinson explained that she removed Park's 1972 diary, a key piece of evidence in the trial, from Park's home in 1974 and returned it to Hundley after Park was indicted in 1977.

Dickinson also testified about a telephone converation between Attorney General Griffin B. Bell and Tongsun Park shortly after Park's indictment. She said Bell spoke with Park from her Watergate apartment while Park remained outside the United States on instructions from Hundley.

Hundley, who Park said coached him "to stay put" in London, said he was he was unaware of Park's call to Bell.

Gravel's defense strategy, according to one source, is designed to confuse the jury of Passman's former constituents and to raise suspicions about Park's connections with the Korean government and his agreement with the Justice Department to testify against Passman.

Gravel dwelled on minor inconsistencies in Park's ledger most of Wednesday. Today he called Park a "pawn of the prosecution" who had no choice but to testify against Passman.

However, Gravel elicited testimony that:

Park did not need Passman's help in early 1972 to regain the lucrative rice trade as charged in the indictment.

Park paid a half million dollars to Gen. Yang Bu Hwan, a top Korean Central Intelligence Agency officer, in 1974 and 1975 as a part of what Park called a "forced loan" which he made as a "wise business decision."

Park regularly paid other Korean officials and often exchanged Korean currency into coveted U.S. dollars for Korean firends and officials.

Park made statements to U.S. and Korean prosecutors prior to his indictment denying payments to Passman.

Park only cooperated with U.S. officials after a $4.5 million tax lien was filed against him and after being ordered to cooperate by the Korean government.

Hundley, who thought Park "was standing up well" to the cross-examination, in commenting about the prolonged trial said, "I know how the South lost the war, but the real question is how they ever ended it!"

Former congressman Richard Hanna, the only other congressman indicted in the Korea bribery scandal, now serving a prison sentence for his involvement with Park, is expected to testify tomorrow.