1) Make a lot of noise. Tell your kids to make a lot of noise. Sing, laugh, call bear names, shout to your children.
The more - the merrier, if it gets quiet - your kids are up to something...

2) Food. Keep it away from you, in a bear-proof container and keep its smells to the minimum.

3) Carry bear spray capable of shooting 30ft. It's not good in your backpack, it should be on your hip at a moments reach. Don't spray it just for practice - old pepper spray smell attracts bears.

4) Consider carrying a firearm on another hip. .357 with good 4+ inch barrel is an absolute minimum, .44Magnum is better, in semi-autos I think .40-caliber is better than .45 (but firearm experts might correct me...). Don't shoot the bear with it unless he's attacking you NOW, otherwise you're pissing him off (warning shot might actually be a good thing - to scare him, but hold it too, it must surprise him like hell, not be a casual noise). If you have to shoot, aim into bears mouth - it's all soft tissue and bear's brain is aligned to it.

Disclaimer: all of it is a compillation of other people stories and suggestions. I was pretty good at avoiding the bear following 1) and 2)