Fırsatlar ve dışsal rassal şoklar altında kalite ve üretim kontrolü

In a production process, opportunities arise due to exogenous or indigenous factors,for cost reduction. In this dissertation, we consider such opportunities in qualitycontrol chart design and production planning for the lot sizing problem. In the firstpart of the dissertation, we study the economic design of X control charts for a singlemachine facing exogenous random shocks, which create opportunities for inspectionand repair at reduced cost. We develop the expected cycle cost and expected operatingtime functions, and invoking the renewal reward theorem, we derive the objectivefunction to obtain the optimum values for the control chart design parameters. In thesecond part, we consider the quality control chart design for the multiple machineenvironment operating under jidoka (autonomation) policy, in which the opportunitiesare due to individual machine stoppages. We provide the exact model derivation andan approximate model employing the single machine model developed in the firstpart. For both models, we conduct extensive numerical studies and observe thatmodeling the inspection and repair opportunities provide considerable cost savings.We also show that partitioning of the machines as opportunity takers and opportunitynon-takers yields further cost savings. In the third part, we consider the dynamic lotsizing problem with finite capacity and where there are opportunities to keep theprocess warm at a unit variable cost for the next period if more than a threshold valuehas been produced. For this warm/cold process, we develop a dynamic programmingformulation of the problem and establish theoretical results on the optimal policystructure. For a special case, we show that forward solution algorithms are available,and provide rules for identifying planning horizons. Our numerical study indicatesthat utilizing the undertime option results in significant cost savings, and it hasmanagerial implications for capacity planning and selection.