Tên luận án: Design and Management of a perishable product supply chain in Mekong Delta Region of Vietnam – A case study of sweet potato in Vinh Long Province
Ngành: Quản trị kinh doanh
Mã ngành: 9340101
Nghiên cứu sinh: Phan Thụy Kiều
Người hướng dẫn: PGS.TS. Ho Thanh Phong
Cơ sở đào tạo: Trường Đại học Quốc tế, Đại học Quốc Gia TP. HCM
1. Tóm tắt luận án
Not only occupying about 60% of area at Me Kong Delta region and about 12% area of Vietnam, sweet potato in Vinh Long Province has a remarkable production, in terms of quantity which is 67.8% of quantity in Me Kong Delta and about 26.9% of Vietnam in total. Sweet potato is considered as the representative fresh agricultural product of the Me Kong Delta region. In the current time, supply chain of sweet potato is inefficient in terms of outdated technology, lack of management, and the issues of market. The dissertation research aims to improve efficiency in management and to cut off the costs of operating supply chain in Vinh Long. The objective of this research is to design the new supply chain of sweet potato so that it meets demand, functions effectively and efficiently, and brings sweet potato to customers with an acceptable price. 
Data for designing supply chain of sweet potato in Vinh Long consists of two categories: primary information from interviewing with local bodies, farmers, traders, and experts, secondary data from the theoretical system of the supply chain, from research, doctoral thesis related to the supply chain and operational efficiency of fresh agricultural products supply chain in Vietnam, especially in the Mekong Delta region; and from consulting local experts in Vinh Long. The supply chain model design is a process with two phases to support strategic decision. The first phase is Multi-objective Optimization with two objectives which are minimizing cost and minimizing transportation time. The solution of the first phase was obtained by using CPLEX software. The second phase is Multiple Attribute Decision Making (MADM) in selection process to select the location. In this stage, the author use a special Analytic Hierarchy Process named Spherical Fuzzy Analytic Hierarchy Process (SF-AHP) and Combined Compromise Solution (CoCoSo) Algorithm in location selection. 
The final output of the model is locations of all components in supply chain of sweet potato, all production quantity and inventory. To accompany with configuration of supply chain, management concepts are introduced and discussed.
2. Những kết quả mới của luận án 
2.1 In terms of current supply chain of sweet potato
Firstly, there are two main channels: As for the export channel, 86% of sweet potato production is exported to China, but prices are often squeezed. For domestic chain, 14% is delivered to private enterprises, companies, processing establishments, supermarkets, wholesale markets, and small shops.
Secondly, farmers are still very spontaneous and small, ignoring the recommendations on breeding techniques, intensive cultivation, and rotation of professional staff. 
Thirdly, the production costs allocated in the following either type of costs: land preparation costs (treatment, dig, pick); breed; plant; irrigation; fertilize; pesticides; collection cost; and other cost. However, the cost of production is made up of features: spontaneous production of improper technical procedures recommends increasing costs of fertilizers and pesticides; labor market scarcity makes labor rental prices high; and mechanization is not high so they still use labor in making soil.
Fourthly, the preservation quality is not high, the preservation time is short, and the rate of post-preservation failure is high, so it cannot meet the demand of the market.
From mapping value chain, the result encourages cooperation among the elements in the chain so that the distribution of benefits moves towards fairness. Specially, the current supply chain for sweet potato in Vinh Long consists of small farmers, farmer cooperatives, producers, traders, wholesalers, retailers, supermarket, distributors, and consumers. All are involved in producing from farm to table tend to operate independently along the supply chain. The infrastructure connecting these partners is very weak. 
2.2 In terms of proposed supply chain of sweet potato in Vinh Long 
Designing the supply chain of sweet potato in Vinh Long comprises two stages:
The first stage is to determine the location of the distribution center (DC) through multi-objective optimization with the two goals of minimizing cost and minimizing transit time. The solution of this stage is obtained through using Mixed Integer Linear Programming (MILP) method together with Compromise Programming. The solution includes the location of the DC along with the amount of traffic between the locations. CPLEX, an optimization programming software of IBM was used for this stage. The model results are as follows: 
(1) The minimum cost solution is to place DC in Tan Quoi commune, Binh Tan district; 
(2) The minimum average transit time solution is to place DC in Long Ho district; 
(3) The compromise solution when considering the two objectives together through the Compromise Planning model is to place DC in Binh Minh Town. 
The second stage is to solve the problem of selection the final location from several possible alternatives, using the Multi-Attribute Decision Making (MADM) method. In the second stage, the author uses the method of hierarchical analysis with fuzzy logic named Spherical Fuzzy AHP (SF-AHP) and the ranking method of alternatives named Combined Compromise Solution (CoCoSo) in selecting the location, the result of the proposed model is the optimal location for the problem of selecting distribution centers. Therefore, it can be concluded that the performance of the proposed model is suitable and applicable in practice for other agricultural products as well. 
In order to collect more information to reflect viewpoints of stake holders as well as to be consistent with the actual situation and socio-economic development of the province Vinh Long, author conducted a survey, consulted with the local authorities, experts including scientists, managers, and leaders of Vinh Long province. Purpose of survey is to collect opinions of attendees about the criteria as well as the importance level between the criteria. The results of selecting the most suitable DC are located in Tan Quoi commune, Binh Tan district, nearest material growing area.
In summary, the new supply chain design for Vinh Long sweet potato includes the choice of DC combined with optimal problem solving when considering production-distribution with minimized costs and transport time to market to overcome the shortage of qualified agricultural warehouses. The best solution for the distribution center located in Tan Quoi - Binh Tan meets both of the above objectives.
3. Các ứng dụng/ khả năng ứng dụng trong thực tiễn hay những vấn đề còn bỏ ngỏ cần tiếp tục nghiên cứu
Cost and transit time are two of key factors, that contributed inefficiently supply chain of agricultural products, reducing the competitiveness compared to other countries, especially agri-fresh produce in reality. Theoretically, to solve problems of optimizing costs and freight time, it is first necessary to determine the optimal route to transport goods, and the distribution center to collect and deliver goods, by using the linear programming problem model. 
Moreover, selecting distribution center location needs to strictly consider elements of local socio-economic developing strategy due to investing cost to build up and material area. So that, using Multiple Attribute Decision Making (MADM) in selection process to select the location. 
- Background: Sweet potato in Vinh Long Province 
- Current situation: Face many obstacles such as huge quantity is in backlog, its price is falling down, exporting is facing with difficulty, mainly depend on China market.
- Problems: Determine the best distribution center (DC) location and the optimal route to transport sweet potato to design the proposed effective and efficient supply chain for sweet potato in Vinh Long Province, Mekong Delta region.
- Methods: Design supply chain of sweet potato in Vinh Long with two phases to support strategic decision. 
As a consequence, a set of tools proposes two mathematical modeling methods to design supply chain of sweet potato in Vinh Long with two phases to support strategic decision:
+ The first stage is to determine the location of the DC through multi-objective optimization with the two goals of minimizing cost and minimizing transit time. The solution of this stage is obtained through using Mixed Integer Linear Programming (MILP) method together with Compromise Programming. The solution includes the location of the DC along with the amount of traffic between the locations. CPLEX, an optimization programming software of IBM was used for this stage. 
+ The second stage is to solve the problem of selection the final location from several possible alternatives, using the Multi-Attribute Decision Making (MADM) method. In the second stage, the author uses the method of hierarchical analysis with fuzzy logic named Spherical Fuzzy AHP (SF-AHP) and the ranking method of alternatives named Combined Compromise Solution (CoCoSo) in selecting the location, the result of the proposed model is the optimal location for the problem of selecting distribution centers. Therefore, it can be concluded that the performance of the proposed model is suitable and applicable in practice for other agricultural products as well. 
+ Next, using SWOT technique to confirm the best DC location solution. And finally, using SAW technique to increase the objectivity for the determination of the location of the DC as well as to match the actual situation and the socio-economic development of the locality.
The results of this study would help local leaders to establish a plan to build and operate an effective supply chain of sweet potato in Vinh Long Province to solve the problem of get the season, lose price for this local flagship product. Moreover, both each direct and indirect stakeholders should be fully responsible for their tasks  in this supply chain. 
Besides, this research is as a chance to review systematic literature for readers and researchers who keened on supply chain management, logistics industry in Vietnam..