物流國際化實務

江蘇海事職業技術學院仲穎InventoryManagementChapter4-2ElementsofInventoryManagementInventoryControlSystemsEconomicOrderQuantityModelsTheBasicEOQModelChapterTopicsElementsofInventoryManagementIn-processinventories在制品Rawmaterialsinventory原材料finishedparts產成品RoleofInventoryElementsofInventoryManagementInventoryCostsOrderingcosts訂貨成本-costsofreplenishingstockofinventory.Expressedasdollaramountperorder,independentof ordersize.Varywiththenumberofordersmade.Includepurchaseorders,shipping,handling,inspection,etc.InventoryControlSystemsAninventorycontrolsystemcontrolsthelevelofinventorybydetermininghowmuch(replenishmentlevel)andwhentoorder.EconomicOrderQuantityModelsEconomicorderquantity經濟訂貨批量,oreconomiclotsize,isthequantityorderedwheninventorydecreasestothereorderpoint.EconomicOrderQuantityModelsBasicEOQModelTheInventoryOrderCycleBasicEOQModel全年持有成本計算Annualcarryingcostequalscarryingcostperunitperyeartimesaverageinventorylevel: Carryingcostperunitperyear=CcAverageinventory=Q/2Annualcarryingcost=CcQ/2. CarryingCostBasicEOQModelAverageInventoryBasicEOQModel全年訂貨成本計算Totalannualorderingcostequalscostperorder(Co)timesnumberofordersperyear.Numberofordersperyear,withknownandconstantdemand,D,isD/Q,whereQistheordersize: Annualorderingcost=CoD/QOnlyvariableisQ,CoandDareconstantparameters.OrderingCostBasicEOQModel全年總成本等于兩者之和Totalannualinventorycostissumoforderingandcarryingcost:TC=CoD/Q+CcQ/2TotalInventoryCostBasicEOQModelTheEOQCostModelTotalInventoryCostBasicEOQModelEOQoccurswheretotalcostcurveisatminimumvalueandcarryingcostequalsorderingcost:EOQandMinimumTotalCostEOQ=SQR（2CoD/Cc）TheEOQmodelisrobustbecauseQisasquarerootanderrorsintheestimationofD,CcandCoaredampened.Example(1of2)I-75CarpetDiscountStore,SuperShagcarpetsales.Givenfollowingdata,determinenumberoforderstobemadeannuallyandtimebetweenordersgivenstoreisopeneverydayexceptSunday,ThanksgivingDay,andChristmasDay.ModelparametersBasicEOQModelCc=＄0.75，Co=＄150，D=10,000yd Optimalordersize

EOQ=SQR（2CoD/Cc）=SQR（2*150*10000/0.75)=2000ydExample(1of2)withoutThanksgivingDay,andChristmasDay.TotalannualinventorycostBasicEOQModelTC=CoD/Q+CcQ/2 =150*10000/2000+0.75*2000/2=1500 Numberofordersperyear Q=10000/2000=5 Ordercycletime=311/5=62.2days(why311=365-52-1-1)EOQAnalysisOverTime(2of2)Foranytimeperiodunitofanalysis,EOQisthesame.ShagCarpetexampleonmonthlybasis:ModelparametersBasicEOQModelCc=＄0.0625peryardpermonth Co=＄150perorder D=833.3peryardpermonth Optimalordersize

EOQ=SQR（2CoD/Cc） =SQR（2*150*833.3/0.0625)=2000ydExample(2of2)BasicEOQModelTotalannualinventorycost TC=125*12=1500peryearTotalmonthlyinventorycost TC=CoD/Q+CcQ/2 =150*833.3/2000+0.0625*2000/2=125permonthEOQAnalysiswithExcelReorderPoint(2of4)ReorderPointandLeadTimeReorderPointThereorderpoint（訂貨點）istheinventorylevelatwhichaneworderisplaced.Ordermustbemadewhilethereisenoughstockinplacetocoverdemandduringleadtime（提前期）。Thise