臺灣博碩士論文加值系統

當缺貨發生時，顧客需求可能會永遠失去。銷售損失的狀況通常發生在完全競爭的市場。缺貨也會造成配銷商與零售商的商譽喪失。針對短生命周期的商品，有限期間的經濟存貨模式會比無限期間的生產規劃模式要來的適當。
本研究延伸以前的傳統經濟訂購量（EOQ）存貨模式，在考量銷售損失及有限的生產規劃期間下，發展一個精確的演算法來求解。以總相關存貨成本(包含訂購成本、持有成本及短缺成本)之極小化為目標，決定最佳之訂購次數與再訂購點。數值範例和敏感度分析驗證本研究所提出模型的正確性及實際運用。分析結果顯示本研究演算法所得到之解略高於非線性整數規劃法所求出之全域最佳解。本研究結果可以提供決策者在存貨系統規劃初期，決定考慮服務水準下之最佳存貨策略。

In a perfectly competitive market, lost sale happens when there is a shortage; demand is ususally lost permanently. Shortages also result in a lost of goodwill for the distributor or retailer. The finite-horizon economic inventory model is more appropriate than the infinite-horizon planning model for product with short life cycles.
This study extends a previous Economic Order Quantity (EOQ) model to include lost sales inventory and finite planning horizon. Exact algorithms are developed for this model. The objectives are to determine an optimal number of orders and reorder point to minimize total relevant cost that consists of order cost, holding cost, and shortages cost. Numerical examples and sensitivity analyses are performed to validate the models and to demonstrate the practical use of the study. The analysis shows that the minimum total relevant cost of the finite planning horizon method using the proposed algorithm in this study is higher than the global optimal solution using integer non-linear programming. Managerial insights are provided for decision makers to implement the optimal inventory policies with service levels that have been determined at the beginning of the inventory system plan.

摘要 ...................................................................................................................................... i
ABSTRACT .......................................................................................................................... ii
ACKNOWLEDGEMENT ..................................................................................................... iii
TABLE OF CONTENTS ...................................................................................................... iv
LIST OF TABLES ................................................................................................................ vi
LIST OF FIGURES ............................................................................................................... vii
CHAPTER 1. INTRODUCTION ......................................................................................... 1
1.1.Introduction ............................................................................................................... 1
1.2.Research Questions ................................................................................................... 3
1.3. Research Scope ......................................................................................................... 3
1.4. Research Objectives ................................................................................................. 4
1.5. Research Framework ................................................................................................ 4
CHAPTER 2. LITERATURE REVIEW .............................................................................. 7
2.1. Researches on Lost Sales Inventory......................................................................... 8
2.2. Researches on Finite Planning Horizon ................................................................... 9
2.3. Research Contribution.............................................................................................. 11
CHAPTER 3. RESEARCH METHODOLOGY .................................................................. 15
CHAPTER 4. MODEL DEVELOPMENT .......................................................................... 17
4.1. Assumptions ............................................................................................................. 17
4.2. Notations ................................................................................................................... 18
4.3. Lost Sales Inventory in Finite Planning Horizon Models ........................................ 18
4.3.1. Normal Distribution ....................................................................................... 20
4.3.2. Cost Parameter ............................................................................................... 21
4.3.3. Total Relevant Cost for the Model ................................................................. 24
4.3.4. Convexity of the Total Cost Function ............................................................ 26
4.3.5. Optimal SolutionUsing Proposed Algorithm Approach ................................ 27
iv
4.3.6. Optimal SolutionUsing Integer Non Linear Programming (INLP) ............... 29
4.4. Service Level Policy ................................................................................................. 30
4.4.1. Service Level Per Order Cycle (SLc) ............................................................ 31
4.4.2. Service Level Per Unit Demanded (SLu) ...................................................... 32
CHAPTER 5. NUMERICAL EXAMPLE AND ANALYSIS ............................................. 35
5.1. Numerical Example and Result Verification ............................................................ 35
5.1.1. Optimal Variable Decision Using The Proposed Algorithm Approach ........ 35
5.1.2. Optimal Variable Decision Using Integer Non Linear Programming (INLP) 37
5.2. Numerical Example for the Service Level Policy Models ....................................... 38
5.2.1. Numerical Example for the Service per order cycle (SLc)Policy .................. 38
5.2.2. Numerical Example for the Service per Unit Demanded (SLu)Policy .......... 39
5.3. Sensitivity Analysis .................................................................................................. 40
5.3.1. Sensitivity Analysis of Parameter .................................................................. 40
5.3.1.1. Sensitivity Analysis of Order Cost (A) ............................................. 41
5.3.1.2. Sensitivity Analysis of Holding Cost (h) .......................................... 42
5.3.1.3. Sensitivity Analysis of Shortages Cost (Cu) .................................... 43
5.3.1.4. Sensitivity Analysis of Demand (D) ................................................. 44
5.3.1.5. Sensitivity Analysis of Standard Deviation of Demand (σ) ............. 45
5.3.1.6. Sensitivity Analysis of Lead Time (L) ............................................. 46
5.3.2. Sensitivity Analysis of Service Level ............................................................ 48
5.3.2.1.Sensitivity Analysis of Service Level per Cycle (SLc) ..................... 48
5.3.2.2. Sensitivity Analysis of Service Level per Unit Demanded (SLu) .... 50
CHAPTER 6. CONCLUSIONS AND FURTHER RESEARCH ........................................ 53
6.1. Conclusion ................................................................................................................ 53
6.2. Future Research ........................................................................................................ 55
REFERENCES ...................................................................................................................... 56
APPENDIX ........................................................................................................................... 59
v
LIST OF TABLES
Table 2.1. State of the art of the research .............................................................................. 13
Table 4.1. Notations .............................................................................................................. 18
Table 4.2. Properties of the normal distribution .................................................................... 21
Table 5.1. Comparison of total relevant cost (TRC) using proposed method ....................... 36
Table 5.2. Summary of the parameters values for the sensitivity analysis ............................ 40
Table 5.3. Sensitivity analysis of order cost (A) .................................................................... 41
Table 5.4. Sensitivity analysis of holding cost (h) ................................................................ 42
Table 5.5. Sensitivity analysis of shortages cost (Cu) ........................................................... 43
Table 5.6. Sensitivity analysis of demand (D)....................................................................... 44
Table 5.7. Sensitivity analysis of standard deviation of demand (σ) ..................................... 45
Table 5.8. Sensitivity analysis of lead time (L) ..................................................................... 46
Table 5.9. Sensitivity analysis of service level per cycle (SLc) ............................................ 49
Table 5.10. Sensitivity analysis of service level per unit demanded (SLu) .......................... 51
vi
LIST OF FIGURES
Figure 1.1. Research framework ........................................................................................... 6
Figure 2.1. Research tree positions ........................................................................................ 12
Figure 3.1. Research methodology ........................................................................................ 15
Figure 4.1. Inventory level under a (Q,r) policy ................................................................... 19
Figure 4.2. Lost sales inventory model with normal demand distribution ............................ 19
Figure 4.3. Flowchart methodology to solve and analyze the model .................................... 28
Figure 5.1. Graphic function of total relevant cost (TRC) .................................................... 38
Figure 5.2. Effect of the parameter changes to the backorder size ........................................ 47
Figure 5.3. Effect of the parameter changes to the total relevant cost (TRC) ....................... 48
Figure 5.4. Effect of the SLc changes to the optimal TRC ................................................... 50
Figure 5.5. Effect of the SLu changes to the optimal TRC ................................................... 52

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