AN 18-year-old man who sexually assaulted a 38-year-old woman was yesterday sentenced to one month in prison. Yeung Kwok-kuen was convicted after trial by magistrate Miss Loh Kim-wan. He pleaded not guilty. Defence counsel Mr Kaiser Kong told Western Court reports showed Yeung had been a slow learner. Mr Kong said Yeung had seen a psychiatrist from the age of seven until the age of 16. The offence took place on August 23 in Des Voeux Road West, Western.