1. Propulsion and Combustion Laboratory, School of Mechanical, Aerospace and Systems Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
2. Environmental Catalysis Laboratory, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-Dong, Pohang 790-784, Korea
3. Technology Center, ORDEG Corporation, 404 Mognae-dong, Danwon-gu, Ansan-si, Gyeonggi-do 425-100, Korea
4. Emission Research Team, Hyundai-Kia Motors, 772-1 Jangduk-dong, Hwaseong-si, Gyeonggi-do 445-706, Korea