Operations Management

Unit 10: Managing Inventories (1)

授課教師： 國立臺灣大學工商管理學系 黃崇興 教授

本課程指定教材為 Operations Management: Processes and Supply Chains, 10th ed., Lee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Pearson Education, ©2013

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Inventory Management

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p.328, 329

Inventory Management Inventory

Inventory and Supply Chains

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p.329 Figure 9.1

Pressures for small inventories

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p.329, 330

Inventory holding costCost of capitalStorage and handling costsTaxes, insurance, and shrinkage

Shrinkage takes three forms Pilferage Obsolescence Deterioration

Pressures for large inventories

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p.330, 331

Customer serviceOrdering costSetup costLabor and equipment utilizationTransportation costPayments to suppliers

Types of Inventory

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p.331, Figure 9.2, 332

Three aggregate categories Raw materials Work-in-process Finished goods

Classified by how it is created Cycle inventory Safety stock inventory Anticipation inventory Pipeline inventory

Cycle Inventory

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p.331

Lot sizing principles The lot size, Q, varies directly with the elapsed

time (or cycle) between orders

Average cycle inventory = = Q + 0

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Q

2

Pipeline inventory

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p.332

Average demand during lead time = DL

Average demand per period = d

Number of periods in the item’s lead time = L

Pipeline inventory = DL = dL

Inventory Reduction Tactics

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p.333, 334

Cycle inventorySafety stock inventoryAnticipation inventoryPipeline inventory

ABC Analysis

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p.334, Figure 9.4

ABC Analysis Stock-keeping units (SKU) Identify the classes so management can

control inventory levels Pareto chart

Economic Order Quantity

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p.335

EOQ Five assumptions

Don’t use the EOQ Modify the EOQ Use the EOQ

Calculating EOQ (cont.)

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p.336 Figure 9.5

Calculating EOQ (cont.)

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p. 336

Annual ordering costAnnual ordering cost = (Number of orders/Year)

(Ordering or setup costs)

Total annual cycle-inventory costTotal costs = Annual holding cost

+ Annual ordering or setup cost

Annual holding costAnnual holding cost = (Average cycle inventory)

(Unit holding cost)

Calculating EOQ (cont.)

p.336 Figure 9.6

Calculating EOQ (cont.)

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whereC = total annual cycle-inventory costQ = lot sizeH = holding cost per unit per yearD = annual demandS = ordering or setup costs per lot

C = (H) + (S)Q

2DQ

Total annual cycle-inventory costp.336

EXAMPLE 9.2The Cost of a Lot-Sizing Policy

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p.337

Calculating EOQ

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p.337, 338

EOQ = 2DSH

Time between orders (TBO)

TBOEOQ = (12 months/year)EOQD

The EOQ formula

EXAMPLE 9.3Finding the EOQ, Total Cost, TBO

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p.338

Managerial Insights

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p.339 Table 9.1

Inventory Control Systems

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p.339,340

Two important questions Nature of demand

Independent demand Dependent demand

Discuss two inventory control systems Continuous review system (Q) Periodic review system (P)

Continuous review system (Q)

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Inventory position = On-hand inventory + Scheduled receipts

– Backorders

IP = OH + SR – BO

p.339,340

Selecting the Reorder PointWhen Demand and Lead Time Are Constant

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p.340 Figure 9.9

EXAMPLE 9.4Placing a New OrderWhen Demand and Lead Time Are Constant

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p.341

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.328, 329 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.329, 330 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.330, 331 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.331, 332 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.331 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.332 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.333, 334 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.334 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.335 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.336 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.336 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.337, 338 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.339, 340 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

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Pearson Education / Lee J. Krajewski, Larry P. Ritzman, and Manoj K MalhotraLee J. Krajewski, Larry P. Ritzman, and Manoj K Malhotra, Operations Management: Processes and Supply Chains, 10th ed., Pearson Education,2012. p.340 依據著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。

2-23Pixabay/ Unknownhttp://pixabay.com/en/ashton-books-book-42701本作品屬公共領域之著作。瀏覽日期： 2013/05/08 。

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Inventory Management...EXAMPLE 9.4Placing a New OrderWhen Demand and Lead Time Are Constant( 各頁標題 )

Pearson Education / Lee J., Larry P. Ritzman, and Manoj K Malhotra,Operations Management: Processes and Supply Chains, 10th ed., P.328-341.本作品以著作權法第 46 、 52 、 65 條合理使用。瀏覽日期： 2013/05/08 。