초록
We analyzed the effect of three different types of inventory systems for saving the total cost using simulation on the system where multiple depots and many retailers disperse on the limited area. Three types of inventory systems are single echelon system with inventory exchange and two-echelon system and the variant two-echelon system. Variant two echelon system is the two-echelon system where the inventory transshipmentsare allowed on every two stage inventory echelons. Inventories kept on every retailer are commonly used for all retailers when certain retailer has stock-out. And when all retailers are stock-out, inventories kept on every depot are commonly used for the retailers whose assigned depots are stock-out. These all three systems are simulated with the constraint of service level on wide range of parameter settings. Simulation results show that cost saving effect appear clear for single echelon system and two-echelon system when shortage cost portion and transportation cost portion becomes large respectively irrespective of depot number. Variant two echelon system seems to be superior to two other systems when transportationcost portion becomes very small. But this superiority is not proved in terms of statistics. So we may conclude that the variant two echelon system may be useless with the higher administrative efforts due to frequent inventory exchange. Also we note that the traditional two echelon system becomes inferior to two other systems in terms of statistics when service level becomes high or when demand variance becomes very large. And inventory integration effect that cost becomes saved when depot number decrease, diminishes when transportation cost or stock-out cost increases irrespective of inventory systems.
