Actually it's not so new, but the Koreanization of the suburbs in the northwest Valley has really taken hold. I think every church my parents tried to drag me into growing up now holds services in Korean or Spanish. Amanda Covarrubias in the LAT:

Koreans have changed the face of Valley neighborhoods such as Northridge, Granada Hills, Porter Ranch and Chatsworth, where signs in Korean and English announce the presence of churches, hair salons, restaurants and home-goods stores catering to Koreans.

Community leaders estimate 50,000 to 60,000 Koreans and Korean Americans live in the Valley. What's more, the San Fernando Valley Korean Business Directory lists nearly 1,500 Korean-owned businesses in the area, including acupuncturists, liquor stores and doughnut shops.

It helps explain why David Lee, the Korean-American owner of more Los Angeles office buildings than anyone else, is often called "a San Fernando Valley physician."