【正文】 Setting OP E D D L T57 Fixed Order Period Systems ? Behavior of Economic Order Period (EOP) Systems ? Economic Order Period Model 58 Behavior of Economic Order Period Systems ? As demand for the inventoried item occurs, the inventory level drops ? When a prescribed period of time (EOP) has elapsed, the ordering process is triggered, ., the time between orders is fixed or constant ? At that time the order quantity is determined using order quantity = upper inventory target inventory level + EDDLT ? . . . more 59 Behavior of Economic Order Period Systems ? After the lead time elapses, the ordered quantity is received , and the inventory level increases ? The upper inventory level may be determined by the amount of space allocated to an item ? This system is used where it is desirable to physically count inventory each time an order is placed 60 EOP = 2S / DCDetermining the EOP ? Using an approach similar to that used to derive EOQ, the optimal value of the fixed time between orders is derived to be 61 Other Inventory Models ? Hybrid Inventory Models ? SinglePeriod Inventory Models 62 Hybrid Inventory Models ? Optional replenishment model ? Similar to the fixed order period model ? Unless inventory has dropped below a prescribed level when the order period has elapsed, no order is placed ? Protects against placing very small orders ? Attractive when review and ordering costs are large ? . . . more 63 Hybrid Inventory Models ? Base stock model ? Start with a certain inventory level ? Whenever a withdrawal is made, an order of equal size is placed ? Ensures that inventory maintained at an approximately constant level ? Appropriate for very expensive items with small ordering costs 64 Single Period Inventory Models ? Order quantity decision covers only one period ? Appropriate for perishable items, ., fashion goods, certain foods, magazines ? Payoff tables may be used to analyze the decision under uncertainty ? . . . more 65 Single Period Inventory Models ? One of the following rules can be used in the analysis ? greatest profit ? least total expected long and short costs ? least total expected costs 66 Some Realities of Inventory Planning ? ABC Classification ? EOQ and Uncertainty ? Dynamics of Inventory Planning 67 ABC Classification ? Start with the inventoried items ranked by dollar value in inventory in descending order ? Plot the cumulative dollar value in inventory versus the cumulative items in inventory ? . . . more 68 ABC Classification ? Typical observations ? A small percentage of the items (Class A) make up a large percentage of the inventory value ? A large percentage of the items (Class C) make up a small percentage of the inventory value ? These classifications determine how much attention should be given to controlling the inventory of different items 69 EOQ and Uncertainty ? The TSC and TMC curves are relatively flat, therefore moving left or right of the optimal order quantity on the order quantity axis has little effect on the costs ? Estimation errors of the values of parameter used to pute an EOQ usually do not have a significant impact on total costs ? . . . more 70 EOQ and Uncertainty ? Many costs are not directly incorporated in the EOQ and EOP formulas, but could be important factors ? Emergency procedures to replenish inventories quickly should be established 71 Dynamics of Inventory Planning ? Continually review ordering practices and decisions ? Modify to fit the firm’s demand and supply patterns ? Constraints, such as storage capacity and available funds, can impact inventory planning ? Computers and information technology are used extensively in inventory planning 72 WrapUp: WorldClass Practice ? Inventory cycle is the central focus of independent demand inventory systems ? Production planning and control systems are changing to support lean inventory strategies ? Information systems electronically link supply chain 73 End of Chapter 14