removeChild
http://www.kirupa.com/forum/archive/index.php/t-269002.html
http://pv3d.org/tag/removechild/
http://www.rockonflash.com/demos/pv3d/docs/org/papervision3d/core/proto/SceneObject3D.html#removeChild%28%29
Material remove 하기
http://forum.papervision3d.org/viewtopic.php?f=12&t=1140
http://destroyyourcomputer.com/blog/material-memory-leak-issue-in-papervision3d/
http://osflash.org/pipermail/papervision3d_osflash.org/2008-July/024111.html
http://www.papervision3d.org/docs/as3/org/papervision3d/materials/MaterialsList.html#removeMaterialByName%28%29
참고
http://cafe.naver.com/multism.cafe?iframe_url=/ArticleRead.nhn%3Farticleid=933 :differences between delete and null in as3.0
http://livedocs.adobe.com/flash/9.0_kr/ActionScriptLangRefV3/flash/events/IEventDispatcher.html : useWeakReference
