scholarly journals PENGELOLAAN PERSEDIAAN PADA PT. X DENGAN PERMINTAAN STOKASTIK DAN VARIABEL LEAD TIME

2018 ◽  
Vol 1 (1) ◽  
pp. 30
Author(s):  
Silvi Rushanti Widodo ◽  
Heribertus Budi Santoso
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Lot Size ◽  
Joint Economic Lot Size

<p><em>PT. X (pemasok) merupakan suatu perusahaan manufaktur yang bergerak dibidang furniture rotan sintetik. PT. X memiliki permasalahan mengenai pengelolaan persediaan dengan distributornya (pembeli). PT. </em><em>X tidak menggunakan pendekatan sistem apapun untuk mengelola persediaannya saat ini, begitu pula yang dilakukan oleh distributornya. Hal ini tentunya akan menimbulkan permasalahan pada jaringan supply chain karena setiap pelaku bisnis tersebut hanya memikirkan sistem pengelolaan persediaan yang paling menguntungkan bagi dirinya sendiri. Hal ini sangat penting karena dalam suatu jaringan supply chain, keoptimalan pasokan produk pada salah satu pihak belum tentu menjadi optimal bagi pihak yang lain. Hal ini tentunya dapat menimbulkan masalah pada biaya produksi, penentuan jumlah cadangan produk (stock), dan waktu pasokan produk dari jaringan supply chain tersebut sehingga solusi terbaik demi keuntungan bersama akan sulit tercapai. Model Joint Economic Lot Size (JELS) mengintegrasikan pengelolaan persediaan dalam supply chain, Pada model ini pemasok atau produsen akan memproduksi sesuai dengan permintaan pembeli atau konsumen dari permintaannya yang tidak menentu dan hanya berupa kisaran jumlah atau stokastik dengan mempertimbangkan variabel lead time. Perusahaan melakukan pengiriman barang sesuai dengan permintaan konsumen sehingga biaya persediaan hanya optimal bagi salah satu pihak. Besarnya penghematan yang dapat dihasilkan dari metode JELS adalah sebesar 0,51% per tahun.</em></p>

scholarly journals Simulation-Based Optimization of a Two-Echelon Continuous Review Inventory Model with Lot Size-Dependent Lead Time

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1014
Author(s):  
Ibrahim Alharkan ◽  
Mustafa Saleh ◽  
Mageed Ghaleb ◽  
Abdulsalam Farhan ◽  
Ahmed Badwelan
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Shop Floor ◽  
Lot Size ◽  
Continuous Review ◽  
Inventory Costs ◽  
Size Dependent ◽  
Simulation Based ◽  
Simulation Based Optimization ◽  
Total Inventory

This study analyzes a stochastic continuous review inventory system (Q,r) using a simulation-based optimization model. The lead time depends on lot size, unit production time, setup time, and a shop floor factor that represents moving, waiting, and lot size inspection times. A simulation-based model is proposed for optimizing order quantity (Q) and reorder point (r) that minimize the total inventory costs (holding, backlogging, and ordering costs) in a two-echelon supply chain, which consists of two identical retailers, a distributor, and a supplier. The simulation model is created with Arena software and validated using an analytical model. The model is interfaced with the OptQuest optimization tool, which is embedded in the Arena software, to search for the least cost lot sizes and reorder points. The proposed model is designed for general demand distributions that are too complex to be solved analytically. Hence, for the first time, the present study considers the stochastic inventory continuous review policy (Q,r) in a two-echelon supply chain system with lot size-dependent lead time L(Q). An experimental study is conducted, and results are provided to assess the developed model. Results show that the optimized Q and r for different distributions of daily demand are not the same even if the associated total inventory costs are close to each other.

A note on the joint economic lot size model with stochastic demand and variable lead time

2016 ◽  
Vol 23 (1) ◽  
pp. 76
Author(s):  
Reza Hosseini Rad ◽  
Jafar Razmi ◽  
Mohamad Sadegh Sangari ◽  
Zahra Fallah Ebrahimi
Keyword(s):  
Lead Time ◽  
Stochastic Demand ◽  
Lot Size ◽  
Joint Economic Lot Size ◽  
Size Model

scholarly journals Improving Supply Chain Profit through Reverse Factoring: A New Multi-Suppliers Single-Vendor Joint Economic Lot Size Model

2020 ◽  
Vol 8 (2) ◽  
pp. 23
Author(s):  
Beatrice Marchi ◽  
Simone Zanoni ◽  
Mohamad Y. Jaber
Keyword(s):  
Supply Chain ◽  
Financial Institution ◽  
Theory And Practice ◽  
Lot Size ◽  
Accounts Receivable ◽  
Financial Decisions ◽  
Supply Chain Finance ◽  
Joint Economic Lot Size ◽  
Supply Chain Financing ◽  
Size Model

Supply chain finance has been gaining attention in theory and practice. A company’s financial position affects its performance and survivability in dynamic and volatile markets. Those that have weak financial performance are vulnerable when operating in environments that are uncertain and financially unstable. Companies adopt various solutions and techniques to manage, effectively and efficiently, the flow of money to and from its suppliers and buyers. Reverse factoring is an innovative technique in supply chain financing. This paper develops a joint economic lot size model where a vendor coordinates operational and financial decisions with its multiple suppliers through the establishment of a reverse factoring arrangement. The creditworthy vendor systematically informs a financial institution (e.g., bank) of payment obligations to selected suppliers, enabling the latter to borrow against the value of the relevant accounts receivable at low interest (borrowing) rates. The paper also presents a numerical example and a sensitivity analysis to illustrate the behavior of the model and to compare the economic and operational performance of a supply chain with and without a reverse factoring agreement. The results show that the establishment of a reverse factoring agreement within the supply chain improves the economic performance and impacts on the operational decisions.

scholarly journals Lead-time Dependent Ordering Cost Reduction and Trade-credit: A Supply Chain Model with Stochastic Demand and Rework

2020 ◽  
Vol 8 (5) ◽  
pp. 5113-5117
Keyword(s):  
Supply Chain ◽  
Cost Reduction ◽  
Lead Time ◽  
Trade Credit ◽  
Chain Model ◽  
Lot Size ◽  
Expected Cost ◽  
Production Run ◽  
Supply Chain Model ◽  
Ordering Cost Reduction

This study focuses on an integrated vendor-buyer supply chain model where the lead-time and ordering cost reduction act dependently. The lead time demand of a product follows a normal distribution. The manufacturing process is imperfect. During production run time, a certain percentage of defective products are produced, which are immediately reworked. Trade-credit financing has been taken into consideration. The goal of this study is to minimize the joint total expected cost by providing an inter-dependent reduction strategy of lead-time and ordering cost along with the determination of the optimal values of lead-time, number of deliveries, order lot size, ordering cost, lead-time crashing cost, and the joint total expected cost. A solution algorithm and a numerical example are presented to illustrate and establish the integrated model. This model can be used in textiles, automobiles and computers industries.

scholarly journals Model Persediaan Pemasok-Pembeli Dengan Produk Cacat Dan Kecepatan Produksi Terkontrol.

2016 ◽  
Vol 15 (2) ◽  
pp. 103
Author(s):  
NELITA PUTRI SEJATI ◽  
WAKHID AHMAD JAUHARI ◽  
CUCUK NUR ROSYIDI
Keyword(s):  
Sensitivity Analysis ◽  
Production Rate ◽  
Lead Time ◽  
Demand Uncertainty ◽  
Lot Size ◽  
Defective Items ◽  
Total Cost ◽  
Joint Economic Lot Size ◽  
Demand Rate ◽  
The Impact

Penelitian ini mengembangkan model persediaan Joint Economic Lot Size (JELS) pada pemasok tunggal pembeli tunggal untuk jenis produk tunggal dengan mempertimbangkan produk cacat dan tingkat produksi terkontrol. Tingkat permintaan pada pembeli bersifat stokastik. Pengiriman dilakukan dari pemasok ke pembeli dalam ukuran lot pengiriman yang sama dan lead time pengiriman bersifat tetap. Produk cacat yang ditemukan oleh pembeli pada saat inspeksi disimpan secara sementara di gudang pembeli hingga pengiriman berikutnya tiba untuk selanjutnya produk cacat dikembalikan kepada pemasok. Fungsi tujuan dari model ini adalah meminimasi total biaya persediaan gabungan pemasok pembeli dengan variabel keputusan, yaitu frekuensi pengiriman, periode review, dan tingkat produksi. Analisis sensitivitas dilakukan untuk melihat pengaruh perubahan parameter-parameter tertentu terhadap model. Hasil yang didapatkan dari analisis sensitivitas menunjukkan bahwa total biaya persediaan gabungan sensitif terhadap perubahan nilai parameter persentase produk cacat, ketidakpastian permintaan, dan permintaan. In this paper, we consider a joint economic lot size (JELS) model consisting of single vendor single buyerwith single product. We intend to study the impact of defective items and controllable production rate onthe model. The demand in buyer side is assumed to be stochastic. The delivery of lot from vendor to buyer is conducted under equal size shipment and the lead time is assumed to be constant. The defective items founded by the inspector in buyer side are carried in buyer’s storage until the next shipment and will be returned to the vendor. The goal of the proposed model is to determine optimal delivery frequency, review period and production rate by minimizing the joint total cost. A sensitivity analysis is performed to show the impact of the changes of the decision variables on model’s behavior. The result from the sensitivity analysis shows that the joint total cost is sensitive to the changes of defect rate, demand uncertainty and demand rate. 

scholarly journals Design and development of a model and optimal planning for supply chain responsibility towards the environment

2021 ◽  
Vol 34 (01) ◽  
pp. 168-185
Author(s):  
Shahram Mokhlesabadi ◽  
Mohammad Reza Kabaranzad Ghadim ◽  
Hasan Ali Aghajani Kasegari ◽  
Mohammad Mahdi Movahedi
Keyword(s):  
Supply Chain ◽  
Reverse Logistics ◽  
Inventory Systems ◽  
Lot Size ◽  
Environmental Implications ◽  
Product Return ◽  
Current Trends ◽  
Joint Economic Lot Size ◽  
Decision Making Processes ◽  
Production Quantity

The responsible management of product return flows in production and inventory environments is a rapidly increasing requirement for companies. This can be attributed to economic, environmental and/or regulatory motivations. Mathematical modeling of such systems has assisted decision-making processes and provided a better understanding of the behavior of such production and inventory environments. This paper reviews the literature on the modeling of reverse logistics inventory systems based on the economic order/production quantity (EOQ/EPQ) and the joint economic lot size (JELS) settings to systematically analyze the mathematics involved in capturing the main characteristics of related processes. The literature is surveyed and classified according to the specific issues faced and modeling assumptions. Special attention is given to environmental issues. There are indications of the need for reverse logistics models' mathematics to follow current trends in ‘greening’ inventory and supply-chain models. The modeling of waste disposal, greenhouse-gas emissions, and energy consumption during production is considered as the most pressing priority for the future of reverse logistics models. An illustrative example for modeling reverse logistics inventory models with environmental implications is presented.

scholarly journals Effects of Unequal Lot Size and Variable Transportation in Unreliable Supply Chain Management

Mathematics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 357 ◽  
Author(s):  
Soumya Kanti Hota ◽  
Biswajit Sarkar ◽  
Santanu Kumar Ghosh
Keyword(s):  
Supply Chain ◽  
Supply Chain Management ◽  
Cost Reduction ◽  
Lead Time ◽  
Carbon Emission ◽  
Optimization Technique ◽  
Lot Size ◽  
Setup Cost ◽  
Chain Management ◽  
Special Cases

The effect of unreliable players on the supply chain management with a single-setup-multi-unequal-increasing-delivery-policy (SSMUID) along with a service-dependent demand and investment is discussed in this model. The manufacturer is unreliable which causes an increase of lead time and shortage. For solving the shortage problem and reducing lead time crashing cost (LTCC), an investment is utilized with the variable backorder price discounts. The number of transportation increases due to the new transportation policy and it causes pollution. Besides the fixed transportation and carbon emission cost (FTCEC), a container dependent carbon emission cost is applied. Some investments for setup cost reduction (SCR), ordering cost reduction (OCR), and quality improvement (QI) are considered. The lead time demand follows a normal distribution. The total cost of the supply chain is optimized and the model is tested numerically. The main intent of this study is to solve the shortage problem which occurs due to unreliability of the manufacturer. The study helps to reduce the unreliability issue of the manufacturer. The objective function is solved by using the classical optimization technique. Numerical results show that the discount for partial backorder enhances the profitability of the manufacturer. The sensitiveness of the parameters are discussed through the sensitivity of analysis and some special cases. Managerial insights provide the applicability of this study among different sectors.

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