WASHINGTON, Jan. 4 - Acknowledging serious flaws in how it has dealt with sexual assault within the military, the Pentagon announced steps today aimed at preventing such crimes, investigating them more thoroughly when they occur and treating victims with more consideration. Defense Department officials said that, from now on, there will be one set of definitions among all services, and at every base within each service, on what constitutes sexual assault. There will also be uniform procedures for dealing with possible victims and suspected offenders, the officials said. "The department understands that our traditional system does not afford sexual-assault victims...