Can you use electronics on a plane?

I'm a South Korean and I'm in America right now. I'm leaving this sunday and I'm going to visit Korea for a few weeks. The plane ride will be long so, I will be bored. I have lots of electronics. I'm bringing my MacBook Air, iPad Air, iPhone 4s, and my Galaxy SIII. Just wondering if I can use them.

Korea, unlike the US, does not currently allow electronics during all phases of flight from what i know. It depends on what carrier you are using. If it is a korean one, they probably won't let you use them during takeoff/landing, if its an american carrier, you will probably be allowed to use them during all of takeoff, but its sketchy with the landing part with the conflicting regulations. Since you will be in korean airspace, you most likely will not be able to use them under 10000 feet, when you are landing.

Well yes some of the electronics can't be used on the airline

I think it is allowed now:

The Federal Aviation Commission has officially approved use of electronic devices in all stages of flight, with a few exceptions.
The new FAA rules apply specifically to e-readers, laptops, tablets and, in some cases, smartphones. But they must be switched to airplane mode or have their cellular signal disabled. Laptops and other larger devices must still be stowed during takeoff and landing.
Previously, use of electronic devices was only permitted above certain altitudes. Now many electronic devices can be used "gate to gate." Individual airlines are implementing the new policy one by one after getting FAA approval.

Dumped, no you can't during take off and landing, and an announcement will be made when you will be able to use it.

Airlines in the US and Canada can operate electronics, but not on all international airlines.