By collaborating with Dmall, established traditional retailers improved their operational efficiency and optimized customer experience. This was achieved through factors such as technology upgrades, a fast and convenient checkout system, instant delivery service, improved supply chain, assortment management, inventory and warehouse management, membership management and marketing. As of April 2018, Dmall has partnered with 3225 offline stores all over the country and has a total of 40 million registered users and over 7 million monthly active users. With cutting edge big data, IoT and AI technology, Zhang and Wumei Holdings are in the process of digitalizing all physical stores, including launching a cashier revolution by featuring Instant Pay, Self-Check Out, Scan & Go, and Smart Cart as part of its tech-based store operations in Wumart stores. Wumei Holdings today operates over 1000 stores nation-wide in Northern, Eastern and North-Western China with annual sales and assets over RMB 50 billion. Through reform and innovation, the group has rejoined as one of the top-tier retail enterprises of China. Earlier this year, Wumart acquired 21 Lotte Mart stores in Beijing from South Korea's Lotte Shopping for around 248.5 billion won ($230.2 million). Many of Wumart's existing large stores have been renovated into a unified shopping experience including catering, hairdressing salons and community services. "As an integral part of the future for Chinese and global retailers, digitization is being accelerated, with Dmall serving as a provider and implementer. By integrating online-offline retail systems using the internet, big data and artificial intelligence, retail digitization will help provide lower costs, greater efficiency, and a better customer experience." "For me, my mission is to continuously improve digital retailing, upgrade the unification of online-and-offline experiences, provide safe and fresh food for society and provide a better income for Wumart's employees," Zhang said on May 31, 2018. In 2006, Zhang arrested based on unjust accusations. In 2008, the Hengshui Intermediate People's Court of Hebei province sentenced him to 18 years in prison on charges of misappropriation, bribery and fraud, and changed the verdict to 12 years for the final ruling in 2009. A total of RMB 52.1 million in fines was also ordered, which was a violation of personal and enterprise property rights. While in prison, he refused to succumb to injustice and spent most of his time reading and researching. During that time he patented four of his own inventions, receiving one top prize and two first class scientific and technological progress awards at a provincial and ministerial level.