Korean-born Sun Hoe Ku and his wife were naturalized as American citizens yesterday and their bosses stopped by to witness the ceremony.

Chief Justice Warren Burger, who heads the Supreme Court where Ku is employed as a carpenter, made sure Ku and his wife, who works as a housekeeper for Mrs. Burger, arrived on time and in style.

Ku, his wife, Mun Ja Ku, and their two children all were carried to federal court in Alexandria in the Burgers' gray, chauffeur-driven limousine, accompanied by Burger and his wife, Elvera.

And while friends, relatives, sponsors and spectators jammed the white-paneled, second-floor courtroom, the white-haired Burger ascended to the bench and watched proudly as the two elder Kus and 67 others swore allegiance to their newly adopted country.

Was it a rare occasion for the Chief Justice?

"I'd say so, yes," said Burger as U.S. marshals escorted him to the chambers of District Judge Albert V. Bryan Jr. before the 20-minute ceremony. "I've never done it before."

Burger, his hand resting on the shoulder of Ku's 10-year-old son, described the family as friends. The Ku children, he said, are "tops in their class, wherever they go."

Ku, a former officer in the South Korean army, and his family came to the United States six years ago. Ku -- who yesterday changed his name to Richard Harrison Khu -- is employed in repairing and refurnishing furniture and woodwork at the court. His wife -- henceforth Alice Monica Khu -- works as a housekeeper at the Burgers' North Arlington home. The family lives in a separate residence on the Burger property, a court spokesman said.

The appearance by "The Chief," as district court personnel dubbed him, created a stir in the normally staid halls and offices of the 51-year-old red brick courthouse in the heart of the city's historic Old Town section.

Security personnel were notified of the visit only a few hours in advance, said chief deputy marshal Roger Ray. Still, law clerks, secretaries and a few local lawyers, drawn by the day's celebrity visitor, were among the approximately 200 on-lookers as Burger, Bryan and senior District Judge Oren R. Lewis took their places.

After the clerk administered the oath of allegiance to the new Americans, Bryan, describing the proceedings as "one of the few times when everyone in the courtroom is a winner," said Burger's presence made the ceremony "doubly memorable.

"He asked if he could participate, and the court, of course, agreed," said Bryan.

Burger, recalling that all four of his grandparents had been immigrants to America about 130 years ago, urged the naturalized citizens to "find a better way of life and help found a greater nation. . . . Your opportunity is as great today as it was when my grandparents came."

Afterward, Burger threaded his way past happy couples kissing and embracing in the hall outside the courtroom and left with his party by a rear door.

"I was surprised by his [Burger's] appearance, but I liked it, too," said J. S. Sawhney, 33, of Annandale, who emigrated from India in 1974 and was among those taking the oath yesterday.

"You have a feeling for where you were born. But God has given everything to this country, and it's up to the citizens whether they make something of it. The ceremony was an exciting moment. If feel kind of proud."