Perencanaan Persediaan Darah di Unit Transfusi Darah (UTD) Palang Merah Indonesia Kota Madiun

UTD PMI Kota Madiun merupakan pemasok darah untuk beberapa Bank Darah Rumah Sakit (BDRS) di wilayah Kota Madiun dan sekitarnya. Tingginya permintaan yang masuk, terkadang permintaan darah tidak dapat dipenuhi dan di sisi lain banyak juga darah yang sudah expired. Permasalahan ini dapat diselesaikan dengan menentukan stok yang aman serta kapan harus dilakukan pemesanan darah kembali. Data yang digunakan dalam penelitian ini adalah jumlah permintaan produk darah Packed Red Cells selama periode 2020 yang dikumpulkan dari database PMI. Pada penelitian ini dilakukan evaluasi sekaligus penentuan stok yang optimal untuk menghindari banyaknya darah yang rusak sekaligus mengurangi biaya persediaan dengan menggunakan metode Continuous Review System. Hasil dari penelitian ini diperoleh persediaan optimal yang harus disediakan PMI Kota Madiun sekaligus rekomendasi untuk menggunakan Two-Bin System dalam penyimpanan persediaan darah, selain itu biaya persediaan dapat berkurang sebesar 40%.

Inventory Policy Control Using a Continuous Review Model Based on Information Systems: A Case Study in a Restaurant Industry

The development of information technology has become a necessity for every company, one of which is the optimization of inventory planning. The joint warehouse owned by the Chickenpedia Restaurant which has to supply various types of raw materials to the three restaurant branches often experiences stock outs and has to make emergency orders resulting in losses. For this reason, it is necessary to control the inventory of raw materials in the shared warehouse so that stock outs can be overcome and losses that arise can be minimized. One of them is by using the Continuous Review method. By using this method, the optimal order quantity and reorder point will be obtained. The weakness is iterative calculation and monitoring of raw material stock manually. For this reason, it is necessary to support an information system to speed up and make it easier to calculate when to place an order and how many orders of raw materials to suppliers so as to reduce the occurrence of running out of raw materials. The Information System can also monitor the stock of raw materials every day in real time based on the number of incoming and outgoing goods that enter the application.

1.79-Approximation Algorithms for Continuous Review Single-Sourcing Lost-Sales and Dual-Sourcing Inventory Models

Stochastic inventory systems with lead times are often challenging to optimize, including single-sourcing lost-sales and dual-sourcing systems. Recent numerical results suggest that capped policies demonstrate superior performance over existing heuristics. However, the superior performance lacks a theoretical foundation. In “1.79-Approximation Algorithms for Continuous Review Single-Sourcing Lost-Sales and Dual-Sourcing Inventory Models,” the author provides a theoretical foundation for this phenomenon in two classical inventory models. First, in a continuous review lost-sales model with lead times and Poisson demand, he proves that a capped base-stock policy has a worst-case performance guarantee of 1.79 by conducting an asymptotic analysis under a large penalty cost and lead time. Second, in a more complex continuous review dual-sourcing model with general lead times and Poisson demand, he proves that a similar capped dual-index policy has a worst-case performance guarantee of 1.79 under large lead time and ordering cost differences. The results provide a deeper understanding of the superior numerical performance of capped policies and present a new approach to proving worst-case performance guarantees of simple policies in hard inventory problems.

On the shortage control in a continuous review (Q, r) inventory policy using αL service-level

Popular measures of product availability in inventory systems seek to control different aspects of stock shortages. However, none of them simultaneously control all aspects of shortages, because stock shortages in inventory systems are complex random events. This paper analyzes the performance of αL service measure, defined as the probability that stockouts do not occur during a replenishment cycle, to cover different aspects of stock shortages when used to design an optimal continuous review (Q, r) policy. We show that explicitly controlling the frequency of replenishment cycle stockouts, using the αL service-level, allows to implicitly control the size of the stockouts at an arbitrary time, the size of accumulated backorders at an arbitrary time, and the duration of the replenishment cycle stockouts. However, the cost of controlling the frequency of replenishment cycle stockouts is greater than the cost of controlling the size of stockouts and the duration of the replenishment cycle stockouts.

PENGENDALIAN PERSEDIAAN BAHAN BAKU MINYAK SAWIT DENGAN MENGGUNAKAN METODE CONTINUOUS (Q) DAN PERIODIC (P) REVIEW DI PT. XYZ

PT. Wilmar Nabati Indonesia,Tbk merupakan perusahaan industri agribisnis yang bergerak dalam bidang jasa pengolahan minyak mentah dengan kegiatan utamanya memproduksi minyak sawit. Berdasarkan sumber dari perusahaan, kerap mengalami kendala dalam pengendalian persediaan bahan baku minyak sawit, khususnya pada Bleaching Earth dan Phosphoric Acid yang disebabkan oleh kurangnya antisipasi dalam perencanaan dan pemenuhan jumlah permintaan konsumen yang berfluktuasi (probalistik) dan jangka waktu pemesanan yang tidak tetap karena adanya penyesuaian dari permintaan konsumen yang belum terencana dengan baik sehingga sering mengalami kekurangan persediaan yang menyebabkan permintaan konsumen tidak terpenuhi serta kelebihan kapasitas persediaan di berbagai gudang penyimpanan. Tujuan dari penelitian yang dilakukan adalah untuk menentukan pengendalian persediaan bahan baku minyak sawit untuk meminimasi total biaya persediaan di perusahaan. Metode yang digunakan adalah metode Continuous (Q) dan Periodic (P) Review. Hasil perhitungan didapatkan total biaya persediaan minimum adalah dengan metode Continuous Review (Q) Lost Sales sebesar Rp .740.144.076 dengan metode perusahaan sebesar Rp. 764.998.500 sehingga penghematan biaya sebesar Rp. 24.854.424 dengan presentase penghematan biaya sebesar 4%. Jumlah pemesanan Bleaching Earth per pesan bulan April 2021-Maret 2020 sebesar 68 kg dan Phosphoric Acid per pesan bulan April 2021-Maret 2022 sebesar 36 ton dengan total biaya persediaan sebesar Rp. 790.430.247,-.

Two-Echelon Inventory Model With Service Consideration and Lateral Transshipment

This paper considers a two-echelon inventory system with service consideration and lateral transshipment. So far, researchers have not extensively considered the use of lateral transshipment for such systems. Demand arrivals at both echelons follow the Poisson process. We introduce a continuous review base stock policy for the system in steady state, which determined the expected level for on-hand inventory, expected lateral transshipment level and expected backorder level. We showed that the model satisfied convexity with respect to base stock level. Computational experiments showed that the model with lateral transshipment performed better that the model without lateral transshipment.

Las aportaciones de Gropius y Wachsmann a la industria de las casas de madera

<div><p>Walter Gropius and Konrad Wachsmann made a significant contribution to the housing prefabrication industry. After the Second World War, they set principles that have served as a basis for continuous revisions in the interests of optimising the industry. The Packaged Houses are a research that shows a continuous review of the processes and constructive systems of prefabricated houses. This article tries to study (following a chronological criterion and focused on the context of this type of construction) the experience of Gropius and Wachsmann and their contributions as a basis for other investigations that, even today, continue their course.</p></div>

A Continuous Review Production-Inventory System with a Variable Preparation Time in a Fuzzy Random Environment

With the increase in the varieties products and the increasing uncertainty about product demand, the production preparation time is a significant factor in addressing these issues. The trade-off between the reduction of the production preparation time and the associated cost remains a critical decision. With this backdrop, this study presents a continuous review production-inventory model with a variable production preparation time and a time-dependent setup cost. The demand during the preparation time is captured through a min-max distribution-free approach. In a stochastic framework, the order quantity, reorder point, and setup time are optimized by minimizing the expected cost considering the time-value effect. Further, a fuzzy model is formulated to tackle the imprecise nature of the production setup time and demand. Two algorithms are developed using an analytical approach to obtain the optimal solution. A numerical illustration is given to present the key insights of the model for effective inventory management. It is observed that order quantity and total cost are more sensitive at the lower side of the optimal setup time rather than at the higher side. The discount rate is also found to be a sensitive factor while minimizing the total expected cost.