scholarly journals Service-oriented performance of inventory models with partial information on unimodal demand lead-time distributions

2020 ◽  
Author(s):  
Gerrit K. Janssens ◽  
Lotte Verdonck ◽  
Katrien Ramaekers
Keyword(s):  
Customer Service ◽  
Lead Time ◽  
Partial Information ◽  
Service Level ◽  
Inventory Level ◽  
Worst Case ◽  
Point Distribution ◽  
Safety Stock ◽  
Demand Distribution ◽  
Customer Service Level

Facing uncertainty in demand, companies try to avoid stock-outs by holding safety inventories, depending on a pre-set customer service level. The knowledge of the demand distribution during lead-time serves to determine the safety inventory level. Many times the distribution is not fully known, except maybe for its range, mean or variance. However literature shows that the performance of holding safety stock strongly depends on the characteristics of the distribution. One option is to protect against the worst case distribution given some information like range or moments. But this worst case is a two-point distribution, bringing unbelief to managers that such an occurrence would ever appear. Mostly they share the opinion that the demand distribution is unimodal. This research develops a technique to derive the safety stock for unimodal demand distributions of which the mode either is known or can be estimated. In this way, the managers obtain solutions to the decision problem including a higher belief that the related type of distribution might appear in practice.

Modeling of an Inventory System with Variable Demands and Lead Times using a Fuzzy Approach

2016 ◽  
pp. 133-151
Author(s):  
Vijay Kumar ◽  
Pravin Kumar
Keyword(s):  
Customer Service ◽  
Lead Time ◽  
Service Level ◽  
Research Topic ◽  
Lead Times ◽  
Inventory Cost ◽  
Safety Stock ◽  
Customer Service Level ◽  
Optimum Order ◽  
Total Inventory

Inventory modeling has always been an innovative research topic for the researchers. It is concerned with minimization of the total inventory cost and maximization of the service level with minimum inventory. In the real world, the demand is always variable; and also the lead time of supply of an item cannot be always fixed due to some unavoidable circumstances. This chapter is focused on an inventory model with shortages where demand quantity and lead time are considered as variable and represented by triangular fuzzy numbers. An expression for optimum order size, reorder point, safety stock and fuzzy total safety stock cost is developed for a fixed customer service level. This model may help the manager to minimize the inventory cost with a maximum service level under the environment of uncertainty and vague information.

Comparative multi criteria analysis and dependent optimisation through integrated supply chain

2014 ◽  
Vol 63 (8) ◽  
pp. 1046-1069 ◽  
Author(s):  
Sanjay Sharma ◽  
Akshat Sisodia
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Service Level ◽  
Inventory Level ◽  
Inventory Policies ◽  
Inventory Cost ◽  
Content Type ◽  
Customer Service Level ◽  
Integrated Supply Chain ◽  
Different Levels

Purpose – The purpose of this paper is to compare various inventory policies and their effect on various performance metrics at different levels of a multi stage supply chain. Later the model is integrated to include optimization of entire supply chain through implementation of collaborative supply chain model. Design/methodology/approach – Alternative inventory policies have been developed at different echelons and a comparison reflecting the usability on various factors such as inventory level, inventory cost and service level is presented so as to support the decision-making process. Various inventory policies such as economic order quantity, periodic ordering (T, M) and stock to demand have been considered. Along with the basic assumptions; lead time, demand variability, variability in demand during lead time, stock out costs have also been included to make the model more applicable to practical situations. Findings – After the selection of most appropriate inventory policy at each level through a decision matrix, the total cost of operating such a supply chain is calculated along with other parameters such as service level and inventory turns. The approach is of aggregating the optimized value at each echelon referred to as aggregated supply chain in the paper. Then the concept of integrated supply chain is introduced which optimizes the supply chain as a whole, rather than aggregating local optima. The comparison is made between the two approaches that prove the integrated supply chain's superiority. Furthermore, dependent optimization is run as it is not practically possible for each echelon to optimize at the same time. Originality/value – Each echelon is allowed to optimize at a time and other echelons assume corresponding values. This final comparative multi criterion analysis is based on the three factors, i.e. inventory cost, customer service level and inventory turnover with different weights assigned to each factor at different levels of a supply chain. Finally a consolidation of results is made to reflect the overall preference which proves that an integrated supply chain best serves all the parameters combined together.

scholarly journals Analisis Pengendalian Persediaan Obat Dengan Metode ABC, VEN dan EOQ di Rumah Sakit Bhayangkara Kediri

2020 ◽  
Vol 5 (2) ◽  
pp. 97
Author(s):  
Abdul Rofiq ◽  
Oetari Oetari ◽  
Gunawan Pamudji Widodo
Keyword(s):  
Customer Service ◽  
Maximum Level ◽  
Service Level ◽  
Safety Stock ◽  
Reorder Point ◽  
Customer Service Level ◽  
Turn Over

<p><strong>A</strong><strong>bstrak</strong><strong>: </strong>Pengelolaan persediaan obat yang optimal memberikan penghematan biaya pengadaan obat. Dua permasalahan sangat penting dalam pengendalian persediaan obat yaitu memutuskan jenis dan jumlah obat yang harus dipesan. Untuk mendapatkan solusi pengendalian persediaan maka diperlukan identifikasi dan analisis permasalahan tersebut. Tujuan penelitian ini menganalisis sistem pengendalian dan meningkatkan efisiensi siklus pengelolaan obat pasien BPJS Kesehatan klasifikasi AE di Instalasi Farmasi Rumah Sakit Bhayangkara Kediri. Obat klasifikasi AE menggambarkan obat dengan indek kritis tinggi dengan pemakaian dan <em>item</em> banyak, selanjutnya dianalisis menggunakan metode ABC, VEN dan EOQ. Jenis penelitian ini adalah penelitian deskriptif analitik, pengambilan data dilakukan secara retrospektif. Data yang digunakan obat pasien BPJS Kesehatan di Instalasi Farmasi Rumah Sakit Bhayangkara Kediri periode Januari - Desember 2018. Pengumpulan data primer dan sekunder melalui observasi dokumen di lapangan dan wawancara dengan pihak terkait. Analisis menggunakan metode ABC, VEN dan EOQ untuk klasifikasi obat AE. Selanjutnya hasil pengolahan data dibandingkan dengan parameter <em>Reorder Point</em>, <em>Inventory Value</em>, <em>Inventory Turn Over Ratio</em>, <em>Customer Service Level</em>, <em>Safety Stock</em> dan <em>Maximum level inventory</em> untuk menilai efisiensi pengendalian persediaan guna memperoleh persediaan obat yang efisien. Penelitian ini diperoleh hasil analisis pengendalian obat pasien BPJS Kesehatan menggunakan metode ABC dan VEN mampu meningkatkan pengelolaan obat menjadi efektif dan efisien khususnya obat katagori AE. Data perencanaan, pengadaan dan pemakaian obat pasien BPJS Kesehatan tahun 2018 dianalisis dengan metode EOQ selanjutnya dibandingkan nilai parameter yang digunakan dapat mengurangi nilai <em>Stock Out</em>, tetapi efektifitas dan efisiensi pengendalian obat tidak tercapai.</p>

scholarly journals Adaptive inventory control system for material items with continuous non-stationary demand

2014 ◽  
Vol 5 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Martin Krajčovič ◽  
Dariusz Plinta
Keyword(s):  
Control System ◽  
Inventory Control ◽  
Customer Service ◽  
Service Level ◽  
Inventory Systems ◽  
Inventory Level ◽  
Inventory Analysis ◽  
Software Module ◽  
Large Numbers ◽  
Customer Service Level

Abstract This paper describes an algorithm of dynamic inventory control system for large numbers of material items with continuous non-stationary demand. It uses principles of pull inventory control systems, statistical inventory analysis and joint replenishment inventory systems. This algorithm was processed in software module (VBA for Excel) and applied in practice. The target of described algorithm is to keep an optimum inventory level and optimum customer service level in terms of inventory control of items with non-stationary demand.

Investigating the value of reducing errors in inventory information from a supply chain perspective

Kybernetes ◽  
2015 ◽  
Vol 44 (2) ◽  
pp. 176-185 ◽  
Author(s):  
Kazim Sari
Keyword(s):  
Supply Chain ◽  
Customer Service ◽  
Lead Time ◽  
Service Level ◽  
Supply Chain Collaboration ◽  
Content Type ◽  
Useful Knowledge ◽  
Lead Time Reduction ◽  
Customer Service Level ◽  
Time Reduction

Purpose – The purpose of this paper is to investigate the value of reducing errors in inventory information from a supply chain perspective. To this end, the benefits of reducing errors in inventory information are compared with those of lead time reduction and supply chain collaboration. Design/methodology/approach – A simulation model is constructed to perform the analysis. Findings – Results show that lead time reduction is the most important strategy for a supply chain in reducing total supply chain cost. In terms of customer service level, on the other hand, strategy of reducing errors in inventory information is observed as the most considerable strategy. However, the results for supply chain collaboration are somewhat unexpected. Namely, in spite of its popularity, supply chain collaboration provides very limited contribution to the supply chain. Practical implications – This research provides useful knowledge for the managers of a business enterprise in prioritizing various supply chain strategies. Originality/value – In supply chain management literature, greater emphasis is given to lead time reduction and supply chain collaboration than dealing with errors in inventory information. This research makes it clear that errors in inventory information should not be underestimated.

Retail supply chain service levels: the role of inventory storage

2016 ◽  
Vol 29 (6) ◽  
pp. 887-902 ◽  
Author(s):  
Asif Salam ◽  
Farhad Panahifar ◽  
P.J. Byrne
Keyword(s):  
Supply Chain ◽  
Customer Service ◽  
Service Level ◽  
Retail Industry ◽  
Inventory Level ◽  
Content Type ◽  
Service Levels ◽  
Product Availability ◽  
Customer Service Level ◽  
The Relationship

Purpose In today’s competitive retail industry the most critical success factor is customer service which is indicated by product availability. It is argued that in the retail industry, product availability is an important measure of quality. The single most vital decision that every retailer needs to make is, how to maximize service level while keeping minimum inventory level. The purpose of this paper is to explain and demonstrate the relationship between inventory level and customer service level. Design/methodology/approach This study examines an inventory system utilizing a simulation model based on company data obtained from a retail fast-moving-consumer goods chain operating in Thailand. Findings The results suggest that the achievement of a responsive service level is dependent on managing an efficient supply chain in addition to logistics cost reductions. The findings also reveal the effect the inventory level has on the service level. From the findings of this study, demand variability and service level have been found to have the most significant influence on the inventory level. From the findings, it can also be shown that real and accurate information is very important for service supply chains. Practical implications The paper promotes the importance of having an appropriate inventory management policy for a retail chain which should be driven by retail companies in order to better balance inventory and service levels. Originality/value The relationship between the inventory level and customer service level lead to different outcomes at different combinations of inventory and service levels. Significant relationships were found between inventory and service levels.

scholarly journals An Integrated Multiechelon Logistics Model with Uncertain Delivery Lead Time and Quality Unreliability

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Ming-Feng Yang ◽  
Yi Lin ◽  
Li Hsing Ho ◽  
Wei Feng Kao
Keyword(s):  
Customer Service ◽  
Lead Time ◽  
Ant Colony Algorithm ◽  
Service Level ◽  
Decision Makers ◽  
Just In Time ◽  
Production Run ◽  
Proposed Model ◽  
Customer Service Level ◽  
Critical Practices

Nowadays, in order to achieve advantages in supply chain management, how to keep inventory in adequate level and how to enhance customer service level are two critical practices for decision makers. Generally, uncertain lead time and defective products have much to do with inventory and service level. Therefore, this study mainly aims at developing a multiechelon integrated just-in-time inventory model with uncertain lead time and imperfect quality to enhance the benefits of the logistics model. In addition, the Ant Colony Algorithm (ACA) is established to determine the optimal solutions. Moreover, based on our proposed model and analysis, the ACA is more efficient than Particle Swarm Optimization (PSO) and Lingo in SMEIJI model. An example is provided in this study to illustrate how production run and defective rate have an effect on system costs. Finally, the results of our research could provide some managerial insights which support decision makers in real-world operations.

scholarly journals Analytical Solution of Safety Stock Determination in Case of Uncertain Unimodal Lead-Time Demand

2018 ◽  
Vol 21 ◽  
pp. 75-80
Author(s):  
Gerrit Karel Janssens ◽  
Lotte Verdonck ◽  
Katrien Ramaekers
Keyword(s):  
Lead Time ◽  
Partial Information ◽  
Service Level ◽  
Performance Measure ◽  
Service Performance ◽  
Upper And Lower Bounds ◽  
Expected Number ◽  
Safety Stock ◽  
A Value ◽  
The Mean

As companies state that a delivery service is important to their customers, an out-of-stock is considered harmful and therefore they keep safety stock in case of uncertain demand. For decision making on the level of safety stock a complete formulation of the distributional form of the demand during lead time is required. In practice, this information may not be available. In such a case, only partial information on the distribution might be available, such as the range, the mode, the mean or the variance. Given a value for a service performance measure, the decision maker, in this case, is not confronted with a single value for the safety stock but rather with an interval. The present research shows how upper and lower bounds of the safety stock are obtained in an analytical way, given a pre-specified service level using a service performance measure, called ‘expected number of units short’. The technique is also illustrated and compared within the framework of the research.

scholarly journals ANALISIS MASALAH TRANSHIPMENT MENGGUNAKAN SOFTWARE LINGO DI PT.SBT

2020 ◽  
Vol 6 (2) ◽  
pp. 94-99
Author(s):  
Niken Septiani Kurnia
Keyword(s):  
Customer Service ◽  
Lead Time ◽  
Service Level ◽  
Customer Service Level

Pengaplikasian model transhipment pada transportasi seringkali dijumpai dalam dunia bisnis, entah untuk konsolidasi ataupun membagi produk menjadi beberapa bagian sampai akhirnya dikirim ke tujuan. Kondisi seperti ini terkadang membuat perusahaan mengeluarkan biaya yang cukup besar untuk transportasi serta lead time produk sampai ke konsumen yang lebih panjang sehingga mempengaruhi customer service level, padahal sejatinya perusahaan menginginkan customer service level yang baik serta keuntungan yang maksimum dengan biaya yang minimum. PT. SBT yang merupakan perusahaan yang bergerak dalam bidang pendistribusian barang bangunan ini juga tidak terlepas dari kegiatan transportasi yang menerapkan sistem transhipment dengan kepemilikan 3 gudang sebagai tempat transit, dimana ketiga gudang ini memiliki lokasi yang berbeda-beda sehingga perlu dilakukan penelitian lebih lanjut apakah dengan adanya ketiga gudang tersebut biaya transportasi yang dikeluarkan sudah optimal atau belum. Penelitian dilakukan menggunakan data sekunder dari penelitian terdahulu dengan tujuan membandingkan hasil metode yang digunakan penelitian terdahulu dengan hasil penelitian ini, sehingga dapat memberikan masukan terbaik bagi perusahaan dalam aspek transportasi guna mencapai tujuan perusahaan. Pendekatan yang digunakan dalam menyelesaikan masalah transhipment ini yaitu menggunakan software Lingo yang tentunya dengan harapan memberikan hasil optimal. Hasil penelitian menunjukkan adanya penurunan total biaya transportasi yang awalnya Rp 3.275.000 menjadi Rp 1.413.000 dengan selisih biaya sebesar Rp 1.862.000 atau sebesar 56,85%.

What should be lean buffer threshold for the forward-reserve warehouse?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bhavin Shah
Keyword(s):  
Mathematical Model ◽  
Customer Service ◽  
Value Added ◽  
Service Level ◽  
Buffer Size ◽  
Value Stream Mapping ◽  
Content Type ◽  
Customer Service Level ◽  
The Impact ◽  
Just Right

PurposeThe assorted piece-wise retail orders in a cosmetics warehouse are fulfilled through a separate fast-picking area called Forward Buffer (FB). This study determines “just-right” size of FB to ensure desired Customer Service Level (CSL) at least storage wastages. It also investigates the impact of FB capacity and demand variations on FB leanness.Design/methodology/approachA Value Stream Mapping (VSM) tool is applied to analyse the warehouse activities and mathematical model is implemented in MATLAB to quantify the leanness at desired CSL. A comprehensive framework is developed to determine lean FB buffer size for a Retail Distribution Centre (RDC) of a cosmetics industry.FindingsThe CSL increases monotonically; however, the results concerning spent efforts towards CSL improvement gets diminished with raised demand variances. The desired CSL can be achieved at least FB capacity and fewer Storage Waste (SW) as it shifts towards more lean system regime. It is not possible to improve Value Added (VA) time beyond certain constraints and therefore, it is recommended to reduce Non-Value Added (NVA) order processing activities to improve leanness.Research limitations/implicationsThis study determines “just-right” capacity and investigates the impact of buffer and demand variations on leanness. It helps managers to analyse warehouse processes and design customized distribution policies in food, beverage and retail grocery warehouse.Practical implicationsProposed buffering model offers customized strategies beyond pre-set CSL by varying it dynamically to reduce wastages. The mathematical model deriving lean sizing and mitigation guidelines are constructive development for managers.Originality/valueThis research provides an inventive approach of VSM model and Mathematical algorithm endorsing lean thinking to design effective buffering policies in a forward warehouse.

Sign in / Sign up

Export Citation Format

Share Document