Development Of Probabilistic Lead Time Model Based On Fuzzy System To Solve Integrated Inventory Problem
Abstract
Supply activity is one of activities involved in manufacturing system in order to
achieve customer satisfaction by supplying parts or products to all organizations level
in supply chain. Coordination of managing inventory system among the organizations
is one of the motivation for developing integrated inventory model. The final aim of
this research are to minimize the total cost caused by holding inventory in warehouse
and maintain long term relationship among the organizations. Common problems
occur in integrated inventory are demand and lead time uncertainty. This research
proposes the development of integrated inventory model by adding delay ratio caused
by non productive time in vendor production process, whereas delay times is the part
of lead time that consist of moving, waiting, and queuing time. This proposed model
uses fuzzy logic to model delay ratio and identify the effect of delay changing to total
cost. The result of initial fuzzy logic model gives MSE and PME value is 2.41E-5 and
22.513% respectively. Fuzzy logic model optimization is conducted using branch and
bound technique by optimizing weight of fuzzy rule consequent. The MSE and PME
after optimization are reduced into 8.96E-8 and 1.170% respectively. Optimal total
cost of integrated inventory is obtained by applying solution procedures. The optimum
result of total cost is Rp. 857,326.25, while quantity (Q) is 1147, and shipment
frequency (n) is 7 at delay 0.0096. Delay prediction calculation is conducted to check
fuzzy logic model validation and the result shows the MSE and PME value 2.41E-7
and 2.20% respectively. The development of integrated inventory model is useful to
respond lead time uncertainty particularly uncertainty due to internal production
process.
Keywords: Lead time, Non productive time, Delay, Fuzzy Logic, and Integrated
Inventory model
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- Industrial Engineering [2231]