Since David Chu has owned his convenience store in the heart of the 14th Street redevelopment area, he has been vandalized, hit by shoplifters and robbed at gunpoint four times in one year alone.

Yet none of his brushes with crime over the four years unnerved the Korean businessman quite as much as his first encounter with American justice.

The day after one of Chu's armed assailants was caught, the youth turned up in Chu's store, shopping.

"It scared everyone to death," Chu said.

"In Korea, anyone who robs or kills will be killed or sentenced to life imprisonment," he said. "Here we find the law is too weak."

Befuddled by a criminal justice system where criminals go free and victims waste work days in court, about 20 Korean business people Saturday met with members of the police's robbery squad for a lesson in coping with American justice.

Armed with slides and a program recorded in Korean, the officers explained how the American system of justice works -- from arrest to conviction.Police brochures outlined holdup prevention techniques, and the officers emphasized how important it was to prosecute cases.

"We have to impress upon them that in order for our criminal justice system to work they must come to court and prosecute people," said Sgt. Donald E. Blake of the robbery division.

"If a business gets a reputation for not prosecuting, the criminals will keep coming back. We know this for a fact."

Though they represent less than 5 percent of the District's population, Korean merchants run half the city's "mom and pop" grocery stores. In 1979, 20 percent of the city's reported armed robberies were in their stores.

Early in January a D.C. police sergeant shopping in a Korean-owned 7-Eleven store in Southeast Washington shot and killed an armed robber who fired two shots, missing everyone.

A grand jury cleared the officer, Sgt. Arnold Nicholson, of any charges in the incident. And the Korean Businessman's Association presented him with a plaque during the workshop.

"We felt Sgt. Nicholson did prevent the killing of one Korean businessman," John Yoon, vice president of the association said in an interview. "We're grateful. We're not trying to praise somebody who kills somebody, but somebody who protects us."

Chu, who is vice president of one of the merchants groups that sponsored the workshop, said the groups are encouraging Korean store owners to report crimes, study crime prevention techniques and follow through with prosecuting cases.

Chu siad merchants are also beginning to air complaints about the police.

"Most complain police come late," he said. Others argue that bilingual police officers are needed to communicate with Koreans who cannot fully describe the crimes in English.

"Koreans think police don't cooperate and police think Koreans don't cooperate. I think we have to get together. As long as we're living here and doing business, we need instruction on how the system works," Chu said.

Adding to the confusion, Chu said, is a debate among Korean merchants as to whether they should arm themselves. Half feel they should, he said, the other half don't.

But because many of them don't understand American law, the merchants' attempts to protect themselves have sometimes backfired, Chu said.

"A businessman with a permit to use a gun in his store chased a robber outside and found it was against the law to carry the gun outside his store. The businessman had to go to court. The crook got away."