Hung-Tso Lin

A case study in a two-stage hybrid flow shop with setup time and dedicated machines

Abstract In this paper we address a scheduling problem taken from a label sticker manufacturing company. The production system is a two-stage hybrid flow shop with the characteristics of sequence-dependent setup time at stage 1, dedicated machines at stage 2, and two due dates. The objective is to schedule one days mix of label stickers through the shop such that the weighted maximal tardiness is minimized. A heuristic is proposed to find the near-optimal schedule for the problem. The performance of the heuristic is evaluated by comparing its solution with both the optimal solution for small-sized problems and the solution obtained by the scheduling method currently used in the shop. As the heuristic is beneficial to the company, it will be implemented in the near future.

Order selection and pricing methods using flexible quantity and fuzzy approach for buyer evaluation

This paper presents the methods for order selection and pricing of manufacturer (supplier) with make-to-order basis when orders exceed production capacity. By quoting the concepts of triangular fuzzy numbers and linguistic variables, a fuzzy approach to evaluating buyers by taking into account both positive and negative criteria is proposed. According to the classified results of buyers, the orders will be produced with priority, declined, or determined by MIP model. The fixed quantity MIP model and flexible quantity MIP model are employed to determine the produced orders along with the production quantity and the reference amount for price reduction. By applying the concept of TOPSIS, the closeness coefficients for satisfaction grades of orders and for ranking values of buyers are used as the adjusting rates in the final pricing MIP model to set segmented price.

Fuzzy application in service quality analysis: An empirical study

Service activities have become the fundamental and dominant factors of the economic system over the past three decades and the significance and influence of service quality have been recognized through the great effect on customer satisfaction and customer loyalty. It should be noted that the assessment results obtained from multiple attributes decision-making problems of diverse intensity, such as service quality evaluation, may be misleading if the fuzziness of subjective human judgment is not taken into account. This paper develops an analysis architecture, which consists of fuzzy measurement of P-I gap, modified P-I analysis for attributes and ranking order determination for subjects, to deal with service quality measurement more effectively. The fuzzy measurement of P-I gap takes advantage of including the vagueness of evaluators judgment. By using the results of modified P-I analysis, effective ways for improving service quality perceptions can be focused on the attributes of high importance yet poor quality; meanwhile, resources or efforts attached to the attributes of low importance and good quality can be shifted to those of high importance yet poor quality. According to the ranking order of subjects, managers could devote more efforts to assist the subjects with inferior rankings to improve the service activities. The proposed analysis architecture can be used to investigate service quality effectively and track the trends periodically. An empirical study is conducted by using the proposed approach.

A job placement intervention using fuzzy approach for two-way choice

A real-world personnel selection or job placement problem based on a two-way choice frame in an enterprise-and-school partnership system is addressed in this paper. This study aims to develop a job placement intervention by taking into account the fuzzy assessment results of the persons involved on both sides to facilitate placement opportunities and satisfaction so that the problem is tackled in a more convincing and workable way. According to the classified results of enterprises and students, the distinction results are screened for final matching. The utility similarities of fuzzy assessments with very good are used to measure the satisfaction grade for the placement results, including enterprise-student matches and student-student combinations. A mixed integer programming model is performed to fulfill the efficient fit from the right policy. Numerical results and simulated application results demonstrate the effectiveness and benefits of the proposed method. Since the proposed method is a value-added matchmaker and can be easily performed, it can also be used to effectively deal with the analogue problems with two-way choice characteristic, such as the choices between advisers and graduate students and between government-expense graduates and different posts.

An efficiency-driven approach for setting revenue target

This paper addresses the efficiency measurement and revenue setting problems drawn from a home improvement company with 22 chain stores in Taiwan. The top management attaches great importance to efficiency analysis of their stores. Furthermore, when the proposal to establish a new store is under development, the regional manager must determine what efficiency level the new store should achieve and what amount of business revenue it should earn. An approach by using the imprecise DEA (IDEA) and inverse IDEA models as core techniques is proposed to deal with such problems. A simulated application illustrates the implementation of the proposed approach.

Efficiency measurement and ranking of the tutorial system using IDEA

This paper considers how to conduct the efficiency measurement and ranking problem of the tutorial system of some higher education institutions (HEIs) in Taiwan more convincingly and persuasively. Measuring the efficiencies of tutors and rewarding the outstanding tutors are conducted once each academic year and have become an important part of the administration practices. The current performance evaluation methods consider only the output factors inhered in vagueness, while the input are neglected. In order to better reflect the actual situations that different tutors consume various amounts of input to produce various amounts of outputs, an IDEA (imprecise data envelopment analysis) model is proposed to measure the efficiencies of tutors under different possibility levels by incorporating the current methods to serve as output factors and additionally considering the input factor. The proposed evaluation approach, which contains efficiency measurement, ranking guide and ties broken rule, can be applied easily to obtain objective and fair results of the addressed problem. A numerical example is used to illustrate the implementation of the proposed approach.

Crew rostering with multiple goals: An empirical study

An empirical crew rostering problem drawn from the customer service section of a department store in southern Taiwan is addressed in this paper. The service section established relevant service facilities and functions to provide services for customers as well as distinguished guests and visitors. The crew rostering task is concerned with assigning multi-functional workers to different types of job and scheduling working shifts for each worker within a given time horizon, where the available and demand workforce vary from one shift to another. The current crew rostering method is a seniority orientation method. In developing the roster under current method, lines of job are generated and then bids are taken in order of decreasing seniority. The most senior worker has the widest range of job lines from which to select so as to best satisfy his/her preference. Successive crew members bid for the remaining lines of job. The current method has some drawbacks. To overcome the drawbacks, this paper develops a problem-specific approach with three stages to deal with the crew rostering problem, making it more equitable and personalized for workers by considering the management goals concerning worker-job suitability, worker-worker compatibility and worker-shift fondness. Due to the vagueness of job characteristics and the personal attributes, fuzzy method is used to improve the evaluation results of suitability, compatibility and fondness. The utility similarities of fuzzy assessments with the linguistic grade of very good are used to measure the fitness grade for the management goals. A linear goal programming model is proposed to fulfill the efficient assignment/match from the right policy. The proposed approach ensures the right workers are assigned to the right jobs, the right workers are placed together in a job and the pleasing working shifts are given to the workers. An illustrative application demonstrates the implementation of the proposed approach.

A CASE STUDY IN A DUAL RESOURCE CONSTRAINED JOB SHOP

In this paper we address a scheduling problem encountered in a manufacturing company producing sewing machine parts. The production system is a dual resource constrained job shop with the characteristics of sequence-independent set-up time, make-to-order policy, and equal-sized transfer batch. A scheduling rule composed of due-date assignment, job dispatching, labour assignment, and arrival-time determination rules is proposed to obtain a better mean absolute lateness performance for the company. A post-implementation study shows that the application of the scheduling rule is satisfactory.

Efficiency Analysis of Chain Stores: A Case Study

An efficiency analysis problem of a hairdressing company is addressed in this paper. The service system has the characteristics of different trade area types, multiple workers with different levels, crisp facilities and expenses and customer relationship orientations. A specialized imprecise data envelopment analysis (IDEA) model is proposed so that the efficiencies of stores from different trade areas can be compared and all workers in different ranks are included. The analysis results exhibit that the inefficiency in resource utilization is largely caused by inefficient operation. Based on the measurement results, eight stores and two stores are aimed with high priority for improving the efficiencies in operation and scale, respectively. The regional manager agrees that IDEA is helpful in evaluating relative efficiency and detecting the reasons caused inefficiency.

JUST-IN-TIME MANUFACTURE OF HOME-USE SEWING MACHINES USING BACKWARD SCHEDULING

This paper addresses production scheduling in a home-use sewing machine company with a centre-satellite factory system. The scheduling problem in this flowshop type involves sequence-dependent setup time, make-to-order policy, onepiece flow processing, and a just-in-time environment, with all orders being delivered exactly on their assigned due-dates. The objective is to find a job sequence that minimizes the inventory level subject to the due-date constraint. A heuristic is proposed to find the near-optimal schedule for the problem. The performance of the heuristic is evaluated by comparing its solution with both the optimal solution and the solution obtained by the scheduling method currently used in the shop.