I painted weight map in 3d coat, but it shows problem. I attached the pictures below. How can I fix? I want to make it smooth

if you just painted and didn't change the mesh,  try importing the new textures to the original model.  looking good

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Just from looking at it. It looks like it could be the skin weights being attached to the arms. So that mesh around the chest is stuck on the arm bones. The skin weights can be changed in CC3. 

If it's not the skin weights interfering. The weight map is possibly too bright. Try turning it down in the weight map section in iclone.

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I edited mesh smooth, then the frills texture became smooth. When I made the character to dance, I noticed the frills are not moving smooth. so I pained skin weight. I painted green so that it can become smooth, but result is not good. the frills are hidden. How can I fix?

ouch,  that's a difficult one.
I'm sure there's a simple answer,  but I'm still looking for it myserlf,  lol ....I've run into bugs and glitches when editing the weight map in cc3 for too long. 

the best results i've had so far with issues like that depended on the tpose  - where arm weight is distributed relatively to how the character will be used.

For example...first of your picture is hard T Pose -  2nd image is an A - pose -  maybe try transferring weights on an a-pose instead of a hard t-pose so the weights are transferred relatively to the pose -  not a far stretch.

then for the rest of the "natural" look,  I'd look into cloth physics so the lace part can bounce around depending on pose.

with cc3,  I've found the more you try to manually fix weights,  the worse it gets,  so if you can't fix something easy in say 15 minutes - reset and try a new approach... sometimes you have to trick the software into getting it right heh!  One example of tricking the program is making the mesh smaller during weight transfer,  then making it big again when "conforming" or other way around,  make weight map too big or small then shrink or enlarge it with conform..

Good luck

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"To define Tao is to defile it" - Lao Tzu

Any mesh which is away from the skin for more that couple of inches and is in between 2 or more influenced bones, require physics. So you need to enable soft cloth and paint underarms mesh with smooth B/W physics map.
It is not an easy thing to properly balance 2 types of weights along with physics mesh controls and collision shapes. But that is the only way.