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In this study, feasibility tests of secondary air injection technology and lean A/F control technology were performed for LEV program using the FTP75 test on a 2.0 DOHC A/T vehicle. Second-by-second emissions and temperatures were evaluated. The temperatures of exhaust gas were measured at exhaust manifold, front of warm up, and the center of warm up converter. At first, amount of secondary air injection was determined with a bench aged warm up converter and a fresh UCC. And then, the performances of secondary air injection and lean A/F control strategy were compared with 80,000km vehicle aged converters(warm up converter, UCC). Both secondary air injection and lean A/F control technologies satisfied the ULEV regulation. This study shows that the lean A/F control strategy can be one of the potential technologies to meet the LEV/ULEV regulations without an active system that need a cost up.

To reduce cold-start emissions that is a bottleneck of tightened regulation, a photocatalyst was suggested and studied. Conventional TWC can reduce more than 96% of harmful emissions after the activation, but under a cold-start condition it needs a lot of energy to activate. During the activation time (light-off time) harmful gases are exhausted without any purification and it makes the conventional TWC difficult to satisfy tightened regulation. A photocatalyst can be activated by light that has wavelengths lower than 380 nano-meters. The activation needs no time and loss of energy like a TWC. To apply the photocatalyst on a vehicle aftertreatment a photocatalyst system was suggested that uses non-thermal plasma as a light source of photocatalyst. The durability of a photocatalyst was also studied with hydrothermal aging method. The properties of aged catalyst were tested with surface area, phase transformation and conversion efficiency of HC.