生產過程不完備且允許部分欠撥的存貨模型

The inventory models with imperfect production process and partial backlogging

賴德勝(TE-SHENG LAI)

指導教授 ： 歐陽良裕

淡江大學/管理學院/管理科學研究所碩士班/碩士(2006年)

https://doi.org/10.6846/TKU.2006.00608

摘要

過去有關一面生產一面銷售的存貨問題研究中，大都是以生產製程均在正常作業下進行作為前提假設，也就是生產製程完備，生產出來的產品均是完美無瑕的。但實務上，由於機器設備在經過長期使用後，可能會發生老化的現象，或人為的機器操作失當導致製程失控( out-of-control )產生不良品。因此，近年來，已有許多學者考慮並建構了生產製程不完備情形下的存貨模型。
然而，有關生產製程不完備的研究文獻，大部份都著重在如何減少不良品的產生和製程設備的維護上，並不探討產品允許缺貨的情形。在現實生活中，當缺貨現象發生時，部分顧客會因對品牌或公司的忠誠度，而願意等候欠撥，部分則會轉往他處，向競爭廠商購買。再者，縱使有顧客願意等候欠撥，其中也有部分會因等候下次補貨的時間過長，而不願意等待欠撥。所以，將允許缺貨並且欠撥率固定或欠撥率與等候補貨的時間長度有關的因素納入模型中，使模型更能接近實際情況，是值得研究的課題。
此外，改善製程品質在企業實務中一直受到高度重視。為達到更佳的品質水準，我們擬藉由投資資金改善生產製程品質，進而減少生產不良品的發生率。
總之，本文提出三個生產製程不完備的存貨模型。第二章我們考慮允許部分欠撥的存貨問題，假設欠撥率為一個固定的常數。第三章將欠撥率與等候補貨的時間長度有關的因素納入存貨模型中。第四章則探討如何運用投資資金來改善生產製程品質，並考慮部分欠撥，且欠撥率與等候補貨的時間長度有關。三個模型均以單位時間總成本有最小值為目標。進一步，對所提出的模型，我們分別以數值範例說明其求解過程，並做敏感度分析，以了解不同參數值改變時對最適解所造成的影響。

關鍵字

存貨 ； 生產過程不完備 ； 部分欠撥 ； 不良品

並列摘要

Among affiliated researches about manufacturer’s selling and producing at the same time, most inventory models run on the premise that production process is in the normal situation, meaning that all factors which might influence product process are totally avoided, and the products are of no defect. However, machine might deteriorate after being used for a long while, what’s more, employee might operate machine in the wrong way, the two possible factors mentioned above might cause production process out of control, producing defective products. As a result, many researchers have built the inventory model on the basis of the imperfect production process.
However, most references about imperfect production process simply focus on how to reduce defective products and maintain production equipment, but when it comes to the products backlogging, they often assumed that which is not allowed to happen. In real situation,when backlogging happens, some customers are willing to wait until replenishment because they are loyal to this brand or company, while others are not. Furthermore, in some cases that some customers who are willing to wait until replenishment originally ,but if they wait too long, while they will more impatient and go elsewhere, may buy the goods from the competitors. As a result, the inventory model with regular backlogging rate, or the willingness of a customer to wait for backlogging during a shortage period declines with the length of the waiting time, involved might be more persuasive and worth treating.
What’s more, enterprises lay high emphasis on improving production process quality nowadays. In order to attain higher production quality level, they invest more in production process quality improvement with the purpose of reducing product defective rate.
In conclusion, this thesis develop three inventory models under the situation that the production process is imperfect. In chapter two, it builds the inventory model allowing partial backlogging rate, assuming which is a constant. In chapter three, the factors related to backlogging rate and customers’waiting time for the next replenishment are involved in the inventory model. In chapter four, it treats how to improve the production process quality by investing, considering partial backlogging rate, which correlates with customers’ waiting time for the next replenishment. The goal of building these inventory models mentioned above are to derive minimum total cost, and among them, the producing time and product quality level are common decision variables. At last, for all models proposed in this thesis, it uses numerical examples and sensitivity analysis to illustrate the effects of the change of the different parameters on optimum solution.

並列關鍵字

Inventory ； Imperfect Production ； Partial Backlogging ； Defective Product

參考文獻

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