There will be snow in February so you will be pretty much limited to exploring the valley on a short visit. There is a small alpine ski area and cross country skiing on the Glacier Point road. Some of the trails out of the valley may be open to hiking some of the way up but may be closed due to snow and ice. The rest of Yosemite including hwy 120 is winter backcountry and only visitable to the well equipped winter backpacker. While you can do a drive through and see a few things Yosemite is a bit of a drive from most places that hold conferences and it's better if you can stay in the valley. While Yosemite is an amazing place in winter it's a bit of an effort for a short visit. California has a lot to offer so for a short visit there maybe something closer to your conference. You don't say where your conference is or how long you have so it's hard to recommend anything.