Forest Products Society 65th International Convention - Poster . POSTER 25 Effect of Chemical Modification of Hybrid Fillers on the Mechanical and Water absorption Properties of Wood Plastic Composites Geum-Hyun Doh and Sun-Young Lee, Korea Forest Research Institute. POSTER 26 Mechanical Properties of Bamboo-Based Lumber Composite and Potential for Structural UseQuality Approval System for Wood Products in Korea - Cost Action E53 May 7, 2010 . Korean government has started quality approval (QA) system for wood products including preservative treated wood, . lumber, wood pellets and wood composite materials. The QA system is based on the two . preservative treated wood, plywood and structural lumber. The QA system becomes effective..