{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T11:14:58Z","timestamp":1779362098575,"version":"3.51.4"},"reference-count":39,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2024,7,20]],"date-time":"2024-07-20T00:00:00Z","timestamp":1721433600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Systems"],"abstract":"<jats:p>Efficient inventory management, including optimal safety-stock levels, is crucial for operational continuity and cost-effectiveness in various industries. This study seeks the optimal inventory management strategy to minimize costs and determine ideal safety-stock levels. It compares five approaches: the company\u2019s (STAR) current \u201cnumber of days\u201d method, two alternative models from the literature (the theory of constraints (TOC) replenishment model and the service-level approach), and two newly developed hybrid methodologies (the TOC replenishment model with ABC\u2013XYZ classification and the service-level approach with ABC\u2013XYZ classification). The analysis focused on financial performance, considering inventory holding and shortage costs. Monthly production plans were established and fixed as constant based on predetermined optimum month-end inventory levels derived from each method. Through simulation, actual month-end inventory levels were assessed, comparing total inventory costs (TICs). While unit holding costs (UHCs) were documented in financial records in the company, unit shortage costs (USCs) were not; thus, USCs were examined in three scenarios. The results show that the second proposed hybrid model consistently outperformed the other four methods, including the company\u2019s current approach, significantly reducing TIC. The analysis emphasizes the importance of demand variation in setting safety stocks and demonstrates the second hybrid methodology\u2019s effectiveness in optimizing safety-stock strategies and improving overall inventory management efficiency.<\/jats:p>","DOI":"10.3390\/systems12070260","type":"journal-article","created":{"date-parts":[[2024,7,22]],"date-time":"2024-07-22T12:20:38Z","timestamp":1721650838000},"page":"260","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Enhancing Inventory Management through Safety-Stock Strategies\u2014A Case Study"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1508-2593","authenticated-orcid":false,"given":"Sema","family":"Demiray K\u0131rm\u0131z\u0131","sequence":"first","affiliation":[{"name":"Department of Industrial Engineering, Marmara University, \u0130stanbul 34722, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3006-9768","authenticated-orcid":false,"given":"Zeynep","family":"Ceylan","sequence":"additional","affiliation":[{"name":"Department of Industrial Engineering, Samsun University, Samsun 55139, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Serol","family":"Bulkan","sequence":"additional","affiliation":[{"name":"Department of Industrial Engineering, Marmara University, \u0130stanbul 34722, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"663","DOI":"10.1108\/IJLM-12-2017-0329","article-title":"An inherent differentiation and system level assessment approach to inventory management: A safety stock method comparison","volume":"30","author":"Jonsson","year":"2019","journal-title":"Int. J. Logist. Manag."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"29","DOI":"10.12700\/APH.14.5.2017.5.3","article-title":"The significance of the integrated multicriteria ABC-XYZ method for the inventory management process","volume":"14","year":"2017","journal-title":"Acta Polytech. Hung."},{"key":"ref_3","first-page":"77","article-title":"An application of xyz analysis in company stock management","volume":"18","year":"2013","journal-title":"Mod. Manag. Rev."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"6496309","DOI":"10.1155\/2019\/6496309","article-title":"A mathematical safety stock model for DDMRP inventory replenishment","volume":"2019","author":"Lee","year":"2019","journal-title":"Math. Probl. Eng."},{"key":"ref_5","unstructured":"Brown, R. (1977). Materials Managements Systems, John Wiley & Sons."},{"key":"ref_6","unstructured":"Ballou, R.H., and Srivastava, S.K. (2004). Chapter 9 inventory policy decisions. Business Logistics\/Supply Chain Management, Pearson Education. [5th ed.]."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1296","DOI":"10.1287\/mnsc.28.11.1296","article-title":"Aggregate safety stock levels and component part commonality","volume":"28","author":"Collier","year":"1982","journal-title":"Manag. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1380","DOI":"10.1287\/mnsc.34.11.1380","article-title":"Determining safety stock in the presence of stochastic lead time and demand","volume":"34","author":"Eppen","year":"1988","journal-title":"Manag. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1579","DOI":"10.1287\/mnsc.36.12.1579","article-title":"Scheduling the production of several items with random demands in a single facility","volume":"36","author":"Gallego","year":"1990","journal-title":"Manag. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1002\/1520-6750(199010)37:5<725::AID-NAV3220370511>3.0.CO;2-O","article-title":"Safety stock reduction by order splitting","volume":"37","author":"Kelle","year":"1990","journal-title":"Nav. Res. Logist. (NRL)"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"959","DOI":"10.1287\/opre.40.5.959","article-title":"Production batching with machine breakdowns and safety stocks","volume":"40","author":"Groenevelt","year":"1992","journal-title":"Oper. Res."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"983","DOI":"10.1080\/002075497195498","article-title":"Joint optimization of lot-sizes, safety stocks and safety lead times in an MRP system","volume":"35","author":"Molinder","year":"1997","journal-title":"Int. J. Prod. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1002\/(SICI)1520-6750(199704)44:3<257::AID-NAV2>3.0.CO;2-7","article-title":"Joint determination of preventive maintenance and safety stocks in an unreliable production environment","volume":"44","author":"Cheung","year":"1997","journal-title":"Nav. Res. Logist. (NRL)"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/S0165-0114(99)00086-X","article-title":"Possibilistic programming in production planning of assemble-to-order environments","volume":"119","author":"Hsu","year":"2001","journal-title":"Fuzzy Sets Syst."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"136","DOI":"10.1016\/j.eswa.2007.06.009","article-title":"Multi-objective inventory planning using MOPSO and TOPSIS","volume":"35","author":"Tsou","year":"2008","journal-title":"Expert Syst. Appl."},{"key":"ref_16","first-page":"9234","article-title":"Multiple-buyer multiple-vendor multi-product multi-constraint supply chain problem with stochastic demand and variable lead-time: A harmony search algorithm","volume":"217","author":"Taleizadeh","year":"2011","journal-title":"Appl. Math. Comput."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1016\/S0377-1237(07)80006-2","article-title":"ABC and VED analysis in medical stores inventory control","volume":"63","author":"Gupta","year":"2007","journal-title":"Med. J. Armed Forces India"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Chen, Y., Li, K.W., and Liu, S.F. (2008, January 12\u201315). A comparative study on multicriteria ABC analysis in inventory management. Proceedings of the 2008 IEEE International Conference on Systems, Man and Cybernetics, Singapore.","DOI":"10.1109\/ICSMC.2008.4811802"},{"key":"ref_19","unstructured":"Er, M., Laili, E.N., and Renny, P.K. (2011, January 17\u201318). Classification of Hospital Pharmaceutical Drug Inventory Items by Combining ABC Analysis and Fuzzy Classification. Proceedings of the International Conference on Advanced Computer Science and Information System (ICACSIS 2011), Jakarta, Indonesia."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"445","DOI":"10.1108\/17410401211212689","article-title":"Integration of Demand Forecasts in ABC-XYZ Analysis: Practical Investigation at an Industrial Company","volume":"61","author":"Reiter","year":"2012","journal-title":"Int. J. Product. Perform. Manag."},{"key":"ref_21","unstructured":"Rusanescu, M. (2014). ABC analysis, model for classifying inventory. Hidraulica, 17, Available online: https:\/\/hidraulica.fluidas.ro\/2014\/nr2\/17-20.pdf."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"120","DOI":"10.17818\/NM\/2016\/SI8","article-title":"The application of ABC analysis to inventories in the automatic industry utilizing the cost saving effect","volume":"63","author":"Kampf","year":"2016","journal-title":"NA\u0160E MORE: Znan. \u010casopis Za More I Pomor."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Zenkova, Z., and Kabanova, T. (2018, January 10\u201312). The ABC-XYZ analysis modified for data with outliers. Proceedings of the 2018 4th International Conference on Logistics Operations Management, (GOL), Le Havre, France.","DOI":"10.1109\/GOL.2018.8378073"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2494","DOI":"10.1111\/itor.12412","article-title":"Multicriteria ABC inventory classification using acceptability analysis","volume":"26","author":"Li","year":"2019","journal-title":"Int. Trans. Oper. Res."},{"key":"ref_25","first-page":"183","article-title":"Various Methods For ABC Analysis Of Inventory in Ms Excel with Examples","volume":"13","author":"Milkova","year":"2019","journal-title":"J. Comput."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"6641","DOI":"10.1007\/s00521-020-05428-y","article-title":"Design of a supply chain network for determining the optimal number of items at the inventory groups based on ABC analysis: A comparison of exact and meta-heuristic methods","volume":"33","author":"Abdolazimi","year":"2021","journal-title":"Neural Comput. Appl."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"012097","DOI":"10.1088\/1742-6596\/1469\/1\/012097","article-title":"Inventory control using ABC and min-max analysis on retail management information system","volume":"1469","author":"Asana","year":"2020","journal-title":"J. Phys. Conf. Ser. IOP Publ."},{"key":"ref_28","unstructured":"Goldratt, E.M. (1990). Theory of Constraints."},{"key":"ref_29","first-page":"334","article-title":"Review on theory of constraints","volume":"3","author":"Tulasi","year":"2012","journal-title":"Int. J. Adv. Eng. Technol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1016\/j.cirp.2012.03.054","article-title":"Simulation based comparison of safety-stock calculation methods","volume":"61","author":"Schmidt","year":"2012","journal-title":"CIRP Ann."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.jmsy.2014.11.008","article-title":"Cost-service tradeoff analysis of reorder-point-lot-size inventory models","volume":"37","author":"Cheng","year":"2015","journal-title":"J. Manuf. Syst."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Thomopoulos, N.T. (2015). Demand Forecasting for Inventory Control, Springer International Publishing.","DOI":"10.1007\/978-3-319-11976-2"},{"key":"ref_33","unstructured":"Radasanu, A.C. (2016). Inventory management, service level and safety stock. J. Public Adm. Financ. Law, 145\u2013153. Available online: https:\/\/www.jopafl.com\/uploads\/issue9\/INVENTORY_MANAGEMENT_SEVICE_LEVEL_AND_SAFETY_STOCK.pdf."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1002\/aic.16421","article-title":"Inventory policies and safety stock optimization for supply chain planning","volume":"65","author":"Brunaud","year":"2019","journal-title":"AIChE J."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Paul, B., Tondihal, S., and Das, B.B. (2021). Safety stock in inventory management and wastage analysis at construction sites. Recent Trends in Civil Engineering: Select Proceedings of TMSF 2019, Springer.","DOI":"10.1007\/978-981-15-8293-6_42"},{"key":"ref_36","first-page":"100164","article-title":"Operations research models and methods for safety stock determination: A review","volume":"7","author":"Carvalho","year":"2020","journal-title":"Oper. Res. Perspect."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"104938","DOI":"10.1016\/j.cor.2020.104938","article-title":"Optimizing production capacity and safety stocks in general acyclic supply chains","volume":"120","author":"Ghadimi","year":"2020","journal-title":"Comput. Oper. Res."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3670","DOI":"10.47191\/ijcsrr\/V5-i9-48","article-title":"Analysis of Inventory Management in Order to Reduce Overstock (Case Study of TVF Footwear)","volume":"5","author":"Lestari","year":"2022","journal-title":"Int. J. Curr. Sci. Res. Rev."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"100026","DOI":"10.1016\/j.sca.2023.100026","article-title":"A new key performance indicator model for demand forecasting in inventory management considering supply chain reliability and seasonality","volume":"3","author":"Tadayonrad","year":"2023","journal-title":"Supply Chain Anal."}],"container-title":["Systems"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-8954\/12\/7\/260\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T15:20:10Z","timestamp":1760109610000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-8954\/12\/7\/260"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,7,20]]},"references-count":39,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2024,7]]}},"alternative-id":["systems12070260"],"URL":"https:\/\/doi.org\/10.3390\/systems12070260","relation":{},"ISSN":["2079-8954"],"issn-type":[{"value":"2079-8954","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,7,20]]}}}