There's no doubt that the Asian financial crisis will affect the U.S. economy in 1998, probably slowing inflation-adjusted growth by about one-half a percentage point. U.S. exporters of electronics, telecommunications, and other capital equipment will probably take the brunt of the slowdown, says Jerry J. Jasinowski, president of the National Assn. of Manufacturers, Washington. The slowdown may significantly help the overall U.S. economy, says Jasinowski, keeping growth at sustainable levels and prolonging the expansion that's going into its seventh year.