Browsing by Author "Simatupang, Togar Mangihut"
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- ItemAn investigation of the dispatching and expediting rules in buffer management : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Production Technology at Massey University(Massey University, 1997) Simatupang, Togar MangihutBuffer Management is a proactive way of controlling the flow of materials on a shop floor. For shops using the Drum-Buffer-Rope (DBR) scheduling system, information on the effectiveness of non-constraint resources can be captured by monitoring the buffer status. Practitioners use this information to initiate improvement efforts and to decide to expedite when some of the inevitable disruptions are likely to undermine shop performance. This study attempts to investigate three areas in Buffer Management: dispatching rules, expediting rules, and variance reduction. The selected dispatching rules are First-Come-First-Served (FCFS), Shortest Processing Time (SPT) and Minimum Slack Time (MINSLK). Both static and dynamic expediting rules are compared. Reduction in the coefficient of variance for processing times from 100% to 50% corresponds to the process of quality improvement. Mean protective capacity of non-constraint resources is varied to represent different levels of loading on the shop. Inventory and due date measures are used to appraise shop performance. Simulation results indicate that the FCFS dispatching rule is the method of choice if due date performance is important. The shop using the SPT dispatching rule produces lower cycle times. The dynamic expediting rule is only preferred in the shop using FCFS and when mean protective capacity is low. The reduction in processing time variability renders a dramatically improved shop performance.
- ItemSupply chain collaboration : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Technology in Decision Science at Massey University(Massey University, 2004) Simatupang, Togar MangihutThere is general acceptance within the literature that supply chain collaboration will become a focus area for research in supply chain management. Although collaboration has been examined widely in a variety of different contexts, relatively little attention has been given to systematically drawing them together. This study is thus conducted to offer an integrative framework in the context of an interorganisational supply chain to define collaboration by identifying its different elements and provides empirical evidence to support the theoretical framework. This framework would further allow the participating members to understand and examine the strategic importance of these elements of collaboration and what needs to be done to gain the benefits of collaboration. The study includes a literature review, the discontent model, a theoretical framework for supply chain collaboration, measuring the level of supply chain collaboration, supporting the theory with empirical evidence, an innovative scheme for benchmarking, and an empirical study of benchmarking supply chain collaboration. The theoretical framework offered in the study incorporates the five elements of collaboration, namely, a collaborative performance system, information sharing, decision synchronisation, incentive alignment, and streamlined intercompany business processes. To provide empirical evidence, supply chain collaboration between retailers and suppliers was chosen as a unit of analysis and data were collected from a survey of New Zealand companies. Based on the survey results, the three empirical studies reported in this thesis provide the basis for testing a new measure for the extent of supply chain collaboration, testing the hypotheses on the relationship between supply chain collaboration and operational performance, and presenting the benchmarks for classifying high and low performing supply chains. Empirical evidence shows that collaboration between retailers and suppliers has a significant influence on operational performance.