First, thanks for the answers.

I can remove those wierd patterns by increasing the ray bias,
but it makes less reflection as bagginsbill said.

Since I'm really newbie to this 3D things, I cannot understand something like "tripling bad polys" now.
I think I have to give up this car (because other one does not makes problem at all),
and have other trials using poser.

I really appreciate to all your helps.
Thanks.

The solution drives me mad.

I blow up the previous installation of uvmapper,
re-download it from uvmapper.com

And it work!

I spend whole day for this poor problem.

Anyway, Thanks you Rorsdors for your kind answer.
Thanks to the other guys who read my posting.

Thie is the procedure I followed

1. Execute uvmapper
2. Load blMilWom.obj
3. Import IT_A_02_Mech_Head_UVS.uvs

the window seems
+-----------------------------------------------+
|    Cyborg Head         MilWom Body   |
|                                                                |
|    nothing                    nothing             |
+-----------------------------------------------+

1. Save the object as IT_A_02_Mech_Head.obj

2. Close the uvmapper

3. Rerun uvmapper

4. Load IT_A_02_Mech_Head.obj

5. Select MilWom Body part (Upper-right part of the window. The color changed to red)

6. Import IT_A_02_Mech_Torso_UVS.uvs

The tutorial says upper-right part should be changed to cyborg torso.
But in my case, the uv mapper print out "Incompatable Facet Structure"
and nothing changes.

I tried several ways, and searched previous answers. But still I cannot solve this problem.
Any help please. Thanks !