Abstract : LTC(Low Temperature Combustion) technology has been studied to see feasibility of the combustion technology applied to heavy-duty engines on the laboratory scale. This study succeeded to develop a demo engine including realized low temperature combustion under partial load conditions. To find the best feasible LTC strategy, various LTC combustion methods such as PPCI, MK and highly diluted mixing controlled LTC were conducted on 6.0L heavy duty diesel engine. Air management system was re-designed to make these combustion scheme stable and the re-designed air system helped expand LTC operating range. This study finally revealed plausible LTC concept to maximize benefit of the alternative combustion technology while overcoming handicaps of the LTC strategy. Key words : Low temperature diesel combustion(저온디젤연소), Partially pre-mixed combustion ignition(예혼합연소), EGR(배기가스 재순환), Low pressure EGR(저압-배기가스재순환), NOx(질소산화물), PM(입자상물질), HD diesel engine(대형디젤엔진) Nomenclature 1) LTC : low temperature diesel combustionPPCI : partially pre-mixed combustion ignitionMK : modulated kineticsCDC : conventional diesel combustionEGR : exhaust gas recirculationHP-EGR : high pressure EGRLP-EGR : low pressure EGRNOx : nitrogen oxidesPM : particulate matterHC : hydro carbon