You are hired as a supply chain consultant to solve an urgent burning issue from VCES Inc., which is a market leader dedicated to the production and commercialisation of industrial products with $9$ manufacturing plants and $4$ distribution centres with $900$ employees. They have a $20,000$ square meter distribution centre $($DC$)$ with local and international customers. The company$$s suppliers send products from overseas and domestic locations. They have different ranges of customers from wholesalers, retailers, and end$-$users.

The DC$/$warehouse has a carrying cost per unit per year of $$0\mathrm{.}50,$ an order cost of $$10$ per order and an average lead time for delivery of $15$ days. The warehouse staff include the DC Manager, supply chain analyst, inbound and outbound supervisors and $50$ employees. Recently they have received numerous complaints from employees regarding inefficiencies and lack of proper optimization.