Browsing by Author "Yao, Ming-Jong"

Now showing 1 - 18 of 18

A COMMON CYCLE APPROACH FOR SOLVING THE ECONOMIC LOT AND INSPECTION SCHEDULING PROBLEM
(2012-02-01)
Yao, Ming-Jong
;
Chen, Shih-Chieh
;
Chang, Yu-Jen
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this study, we consider an imperfect production system in which the manager not only faces the Economic Lot Scheduling Problem, but also needs to conduct multiple inspections during a production lot of any product. Inspection plays an important role in an imperfect production system since it saves the cost from producing and restoring defective items though it also incurs extra inspection cost at the same time. In this study, we employ the common cycle approach in which all the products share the same replenishment cycle, and adopt a consensus inspection policy. The focus of this study is to determine the optimal cycle time and an optimal production and inspection schedule that minimize the total cost per unit time. We formulate a mathematical model in which we take into accounts both the production capacity and inspection capacity constraints. Also, we conduct full theoretical analysis and propose an effective search algorithm for solving an optimal solution. Our numerical experiments demonstrate the effectiveness of the proposed search algorithm.
A NEW COOPERATIVE SCENARIO FOR SUPPLY CHAINS USING COMMON REPLENISHMENT EPOCHS
(2009-09-01)
Yao, Ming-Jong
;
Chiou, Chuang-Chun
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this paper, we propose a new cooperative scenario for supply chains using common replenishment epochs based on the mathematical model presented in Viswanathan and Piplani's [25] paper. In order to solve an optimal solution for the cooperative scenario, we first conduct a theoretical analysis on the optimal cost function of the mathematical model. Then, we propose an efficient search algorithm by utilizing our theoretical results on the cooperative scenario. Also, we introduce a saving-sharing mechanism that could motivate the buyers to cooperate with the vendor. Importantly, the proposed saving-sharing mechanism assists the supply chain system to create a multi-win situation among the vendor and the buyers. Using the 48 sets of data in Viswanathan and Piplani's [25] paper, we demonstrate that the proposed cooperative scenario could attain significant improvement on the costs for both the vendor and the buyers in comparison to the Stackelberg-game scenario.
A new spanning tree-based genetic algorithm for the design of multi-stage supply chain networks with nonlinear transportation costs
(2009-06-01)
Yao, Ming-Jong
;
Hsu, Hsin-Wei
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
The design of configuration and the transportation planning are crucial issues to the effectiveness of multi-stage supply chain networks. The decision makers are interested in the determination the optimal locations of the hubs and the optimal transportation routes to minimize the total costs incurred in the whole system. One may formulate this problem as a 0-1 mixed integer non-linear program though commercial packages are not able to efficiently solve this problem due to its complexity. This study proposes a new spanning tree-based Genetic Algorithm (GA) using determinant encoding for solving this problem. Also, we employ an efficient heuristic that fixes illegal spanning trees existing in the chromosomes obtained from the evolutionary process of the proposed GA. Our numerical experiments demonstrate that the proposed GA outperforms the other previously published GA in the solution quality and convergence rate.
AN EFFICIENT HEURISTIC FOR TRANSPORT FLEET MAINTENANCE SCHEDULING IN A MAINTENANCE SYSTEM WITH LIMITED CAPACITY
(2014-10-01)
Yao, Ming-Jong
;
Huang, Jia-Yen
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In the real world, the managers of a transportation fleet need to carefully determine the maintenance cycles of vehicles so as to minimize the average total costs (including the operating costs and the maintenance costs). Furthermore, since the maintenance system is usually equipped with limited manpower and facilities, it has limited capacity to provide maintenance service for the transportation fleet. Therefore, we are motivated to determine the optimal maintenance cycle of vehicles and to generate a feasible maintenance schedule of a transport fleet in this study. To solve this problem, we first obtain candidate solutions by solving an unconstrained model using a search algorithm. Then, we test feasibility for each one of these candidate solutions. Finally, among these candidate solutions, we pick the \'best\' solution that secures a feasible maintenance schedule with the minimum average costs. Based on our random experiments, we demonstrate that the proposed search algorithm could effectively solve the Transportation Fleet Maintenance Scheduling Problem in a maintenance system with limited capacity.
AN EFFICIENT SEARCH ALGORITHM FOR OBTAINING THE OPTIMAL REPLENISHMENT STRATEGIES IN MULTI-STAGE JUST- IN-TIME SUPPLY CHAIN SYSTEMS
(2009-02-01)
Yao, Ming-Jong
;
Hsu, Tien-Cheng
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this study, we focus on the coordination of the replenishment activities among all firms in a multi-stage supply chain system in which Just-In-Time (JIT) philosophy applies. Similar to all JIT systems, kanban is used to control information flows and material flows between two adjacent manufacturing plants, which is called a kanban stage. In this supply chain, suppliers provide raw materials to the manufacturing plant in the first kanban stage and end-products are delivered from the plant in the last kanban stage to the warehouses or directly to the customers. Studies in the literature formulated this problem as a Mixed-Integer Non-Linear Program (MINLP). The objective of this study is to propose an efficient search algorithm that solves an optimal solution for this MINLP model. We conduct theoretical analysis on the optimality structure of the model and assert that the optimal cost curve is piece-wise convex. The characteristics of the optimal cost curve, especially the "junction points", provide essential foundation to the design of our search algorithm. Also, in order to reinforce the effectiveness of the proposed search algorithm, we utilize a relaxation of the problem to obtain tight bounds on the search range. Using randomly generated instances in our numerical experiments, we demonstrated that
An integrated algorithm for solving multi-customer joint replenishment problem with districting consideration
(2020-06-01)
Yao, Ming-Jong
;
Lin, Jen-Yen
;
Lin, Yu-Liang
;
Fang, Shu-Cherng
;
運輸與物流管理系註：原交通所+運管所
This paper studies a multi-customer joint replenishment problem with districting consideration (MJRPDC) which is of particular importance to a company that outsources its transportation and delivery operations to a third-party logistics (3PL) service provider. To solve the problem, we first propose an innovative search algorithm for solving the traditional multi-customer joint replenishment problem in a given zone. Then we design a GA-based framework to handle the corresponding districting problem based on the performance of each district evaluated by using the proposed search algorithm. The proposed methodologies are demonstrated by using an example of solving MJRPDC for a bank.
AN INTEGRATED APPROACH FOR THE OPERATIONS OF DISTRIBUTION AND LATERAL TRANSSHIPMENT FOR SEASONAL PRODUCTS - A CASE STUDY IN HOUSEHOLD PRODUCT INDUSTRY
(2011-05-01)
Yao, Ming-Jong
;
Lin, James T.
;
Yang, Chen-Hao
;
運輸與物流管理系註：原交通所+運管所
;
工業工程與管理學系
The household product industry often suffers from problems of high operational costs and/or lost sales from selling seasonal products since managers in different divisions/stages of the supply chain make their decisions independently. We are therefore motivated to propose an approach that integrates the operations in the three stages of a supply chain for the management of seasonal products. The goal of this study is to minimize the total costs incurred for the seasonal products in the whole selling period. In the first stage, we employ a newsvendor model to determine the optimal one-time-only order quantities of the seasonal products. Then, we utilize a clustering analysis in the second stage to categorize seasonal products into groups, and establish an optimal replenishment policy for the products in the same group. Finally, the third stage starts when the warehouse runs out of its inventory. We formulate a mathematical model to determine the optimal transshipment quantities among all of the retailers to minimize the expected total costs incurred for the rest of the selling period. Taking a household product company in Taiwan as our case study, we demonstrate the implementation of the proposed (integrated) approach. Based on the real-world data of 17 seasonal products, we show that our integrated approach significantly outperforms the company's current approach. Therefore, our integrated approach may serve as an effective decision support tool for the distribution and lateral transshipment of seasonal products in the household product industry.
NEW HEURISTICS FOR SOLVING THE ECONOMIC LOT SCHEDULING PROBLEM WITH REWORKS
(2011-02-01)
Chang, Yu-Jen
;
Yao, Ming-Jong
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this study, we are interested in the economic lot scheduling problem (ELSP) that considers manufacturing of the serviceable products and remanufacturing of the rework products. In this paper, we formulate a mathematical model for the ELSP with reworks using the common cycle approach in which only one manufacturing lot and only one rework lot for each product exist during a common cycle. In order to solve this problem, we propose two heuristics that not only search for the optimal cycle time and an optimal production sequence, but also utilize a simple scheduling heuristic to schedule the starting time of all the manufacturing and rework lots so as to minimize the average total costs. The first heuristic is a simple heuristic that employs a 2-opt search to obtain a close-to-optimal production sequence. The second heuristic, which is a refined version of the simple heuristic, employs a bisection search to look for an optimal cycle time. In our numerical experiments, we compare the effectiveness of both heuristics using randomly generated instances.
On the Optimal Inventory Classification and Replenishment Strategies of Pharmaceutical Items: A Case Study in TCVGH
(2010)
Yao, Ming-Jong
;
Hsu, Hsin-Wei
;
Yu, Weiyin
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
Over the last decade, Veterans General Hospital in Taichung (TCVGH) has experienced an upsurge in the number of patients who requested for medical service each day. Such a trend brings the managers in Pharmacy the challenges of significant increase in the inventory holding costs, substantial growth in the number of pharmaceutical items and considerable raises in the complexity of inventory control and management. To face up to these challenges, the managers are desperate for a systematic infrastructure and more efficient approaches to control the inventory of the pharmaceutical items. The focus of this research is to bridge the expertise of both parties (namely Veterans General Hospital in Taichung and Tunghai University) so as to not only enhance knowledge transfer between medical domains and academia, but also upgrade the efficiency of Pharmacy in TCVGH by introducing new management techniques. In order to assist the managers in Pharmacy to overcome the challenges, this research plans to build a "pipeline" through the supply chain of the suppliers, pharmacy and the patients to reduce the inventory holding in TCVGH. We propose to reach our goal by using the four-phase scheme as follows. (1) Demand analysis: We first investigate the sources and the patterns of demand for the pharmaceutical items by the history of prescription fulfillment. (2) Supply characteristic analysis: We should conduct a supply characteristic analysis since the characteristics of the suppliers, lead time, bargaining power and special ordering rules usually have significantly impact on the purchasing strategy of a pharmaceutical item. (3) Pharmaceutical items classification: After finishing demand analysis and supply characteristic analysis, we may categorize the pharmaceutical items into groups in which each item may use a common purchasing strategy. (4) Optimal purchasing policy derivation: For each category of pharmaceutical items we will formulate a mathematical model and derive an optimal algorithm (or a closed solution) for obtaining an optimal purchasing policy so as to minimize the total inventory costs per unit time. This research expects to deliver the managers in TCVGH a useful decision support system to significantly improve the efficiency of Pharmacy by reducing the inventory costs, upgrading the service level to the patient and improving the replenishment process from the suppliers.
On the optimal lot-sizing and scheduling problem in serial-type supply chain system using a time-varying lot-sizing policy
(2013-02-01)
Huang, Jia-Yen
;
Yao, Ming-Jong
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this paper, we solve the optimal sequencing, lot-sizing and scheduling decisions for several products manufactured through several firms in a serial-type supply chain so as to minimise the sum of setup and inventory holding costs while meeting given demand from customers. We propose a three-phase heuristic to solve this NP-hard problem using a time-varying lot- sizing approach. First, based on the theoretical results, we obtain candidate sets of the production frequencies and cycle time using a junction-point heuristic. Next, we determine the production sequences for each firm using a bin-packing method. Finally, we obtain the production times of the products for each firm in the supply chain system by iteratively solving a set of linear simultaneous equations which were derived from the constraints. Then, we choose the best solution among the candidate solutions. Based on the numerical experiments, we show that the proposed three-phase heuristic efficiently obtains feasible solutions with excellent quality which is much better than the upper-bound solutions from the common cycle approach.
Optimal lot-sizing and joint replenishment strategy under a piecewise linear warehousing cost structure
(2017-03)
Yao, Ming-Jong
;
Huang, Jia-Yen
;
交大名義發表
;
National Chiao Tung University
In the general lot-sizing replenishment problem, warehousing costs are considered as part of the inventory holding cost. When decision makers need warehouse space to store their products, they generally think about the warehousing cost as included in the inventory cost. In this study, we investigate an optimal lot-sizing and replenishment problem under a piecewise linear warehousing cost structure. Theoretical analysis of the optimality structure of a model of multiple stock-keeping units with joint inventory costs is conducted, and an effective search algorithm is proposed. Based on our random experiments, we demonstrate that our search algorithm outperforms the approach that the existing literature offers as solution.
Optimal lot-sizing and joint replenishment strategy under a piecewise linear warehousing cost structure
(2017-03-01)
Yao, Ming-Jong
;
Huang, Jia-Yen
;
交大名義發表
;
National Chiao Tung University
In the general lot-sizing replenishment problem, warehousing costs are considered as part of the inventory holding cost. When decision makers need warehouse space to store their products, they generally think about the warehousing cost as included in the inventory cost. In this study, we investigate an optimal lot-sizing and replenishment problem under a piecewise linear warehousing cost structure. Theoretical analysis of the optimality structure of a model of multiple stock-keeping units with joint inventory costs is conducted, and an effective search algorithm is proposed. Based on our random experiments, we demonstrate that our search algorithm outperforms the approach that the existing literature offers as solution.
Optimal replenishment and inventory financing strategy in a three-echelon supply chain under the variable demand and default risk
(1970-01-01)
Yao, Ming-Jong
;
Lin, Jen-Yen
;
Lee, Chieh
;
Wang, Po-Hung
;
交大名義發表
As supply chains span across one or more continents, an intermediate firm becomes an inevitable supply chain component. While seller-financing options (e.g. delay in payment), are well studied, researchers have rarely investigated them from the perspective of an intermediate firm in a supply chain. We construct a three-echelon supply chain that consists of a supplier, distributor, and retailer. In our model, the supplier and distributor may offer seller financing to their buyer, but only the distributor is subject to the buyer's default risk. We consider a seller-financing supply chain wherein either all or none of the sellers premise delay in payment and a special case where the distributor may coordinate with the supplier or retailer. An algorithm solves optimal replenishment and delay-in-payment decisions. Numerical analyses illustrate managerial insights, which show that when the retailer's default risk is high, the distributor's best strategy is not to offer any delay-in-payment. When the distributor-retailer coordination can subsidise the retailer's default risk, the distributor's best strategy is coordination with the retailer and bargaining for more financial support from the supplier. In contrast, as the retailer's default risk is inevitable, the distributor-supplier integration is the optimal supply chain financing strategy.
Scheduling of transportation fleet maintenance service by an improved Lipschitz optimization algorithm
(2014-05-04)
Yao, Ming-Jong
;
Huang, Jia-Yen
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
This study proposes a new and improved Lipschitz optimization algorithm to obtain an E-optimal solution for solving the transportation fleet maintenance-scheduling problem. It employs a procedure based on slope-checking and step-size comparison mechanisms to improve the computational efficiency of the Evtushenko algorithm. Our numerical experiments used 36,000 randomly generated instances to compare the run time and solution quality of our proposed algorithm with the alternative approach in the literature. Our results indicate that the run time of the proposed algorithm could be significantly improved by more than 80% in over 50% of instances in our numerical experiments. We conclude that our proposed algorithm significantly improves the computational efficiency of the conventional Evtushenko algorithm.
Solving the economic lot scheduling problem with multiple facilities in parallel using the time-varying lot sizes approach
(2009)
Yao, Ming-Jong
;
Chang, Yu-Jen
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
The conventional Economic Lot Scheduling Problem (ELSP) is concerned with the lot sizing and scheduling of several products so as to minimize the average total costs on a single facility. This study is interested in an extension of the ELSP, namely, the ELSP with multiple identical facilities in parallel (which is also called the multi-facility ELSP). In order to solve this problem efficiently, we propose two solution approaches in a two-phase scheme in this study. In the first phase, we use an existing heuristic and a genetic algorithm to search for better product assignments that determine which product should be produced on which facility. When an assignment is secured, we employ a Time-Varying Lot Sizes (TVLS) heuristic to obtain a feasible production sequence (or schedule) for each facility in the second phase. Our numerical experiments show that our approaches outperform an existing heuristic in the literature when the problem size is large and the facility utilization rate is high. On the other hand, we have an interesting observation that was never reported in the literature, namely, the TVLS approach may obtain worse solutions than a well-known upper bound in the literature for some cases.
SOLVING THE OPTIMAL RESOURCE ALLOCATION IN MULTIMODAL STOCHASTIC ACTIVITY NETWORKS USING AN OPTIMAL COMPUTING BUDGET ALLOCATION TECHNIQUE
(2018-01-01)
Lin, Jen-Yen
;
Yao, Ming-Jong
;
Chu, Yi-Hua
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
The problem of optimal Resource Allocation in Multimodal Stochastic Activity Networks (RAMSAN) has been studied for more than a decade. Many researchers proposed solution approaches, including dynamic programming and meta-heuristics, for solving the RAMSAN, and they commonly applied Monte Carlo Simulation (MCS) for evaluating the objective function values for the candidate solutions. However, since the computational load of MCS is very demanding, the solution approaches using MCS become impractical, even for only medium-size problems. In this study, we propose a Genetic Algorithm (GA) with an Optimal Computing Budget Allocation (OCBA) approach for solving the RAMSAN. We utilize the technique of OCBA to optimally allocate the computational budget among the candidate solutions in the evolutionary process of GA for evaluating their objective functions. Based on the benchmark instances in the literature, we demonstrate the proposed GA with OCBA is more effective than the other solution approaches in the literature and a GA without using OCBA.
THE EOQ MODELS UNDER BOTH OPTIONS OF CASH DISCOUNT AND DELAY IN PAYMENT
(2014-07-01)
Lin, Jen-Yen
;
Li, Si-Xian
;
Yao, Ming-Jong
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this paper, we propose a new EOQ model considering both options of cash discount and delay in payment and allowing two-stage payments. In business transactions, the retailer may obtain cash discount when the payment is done before cash discount due date designated by the supplier. On the other hand, the supplier may offer a fixed credit period to encourage the retailer\'s demand since the retailer may keep accumulating revenue and earning interest during the credit period before making its payment. The studies in the literature allow only one between either of the two options. Considering both options and allowing two-stage payments, this study proposes a new EOQ model and two effective algorithms that assist the retailer to obtain the optimal replenishment and payment strategy. Our numerical experiments show that the proposed EOQ model with two-stage payment strategy could be superior to the single-stage ones in the literature.
The joint replenishment problem with trade credits
(1970-01-01)
Lin, Jen-Yen
;
Yao, Ming-Jong
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
It is a widespread financial practice in procurement management for a supplier aiming to attract customers to offer trade credits when customers make inquiries about the sold products. In this paper, we examine the joint replenishment problem considering trade credits (JRP-TC) under the power-of-two (PoT) policy. We formulate a mathematical model and conduct an analysis that reveals insights into the properties of the optimal objective function. From there, we propose an effective search algorithm that obtains the global optimal solution for the JRP-TC under the PoT policy. Our complexity analysis shows that the JRP-TC and the conventional joint replenishment problem under the PoT policy are pseudo-polynomial time solvable.