• 대한산업공학회지
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• 제24권3호
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• pp.345-357
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• 1998

This paper focuses on production planning and scheduling problems in an assembly system operating on a make-to-order basis. Due dates are considered as constraints in the problems, that is, tardiness is not allowed. Since the planning problem is a higher-level decision making than the scheduling problem, the scheduling problem is solved using a production plan obtained by solving the planning problem. We suggest heuristic procedures in which aggregated information is used when the production planning problem is solved while more detailed information is used when the scheduling problem is solved. Since a feasible schedule may not be obtained from a production plan, an iterative approach is employed in the two procedures to obtain a solution that is feasible for both the production planning and scheduling problems. Computational tests on randomly generated test problems are done to show the performance of these algorithms, and results are reported.

• 산업경영시스템학회지
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• 제38권3호
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• pp.78-86
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• 2015

Up-to-date business environment for manufacturers is very complex and rapidly changing. In other words, companies are facing a variety of changes, such as diversifying customer requirements, shortening product life cycles, and switching to small quantity batch production. In this situation, the companies are introducing the concept of JIT (just-in-time) to solve the problem of on-time production and on-time delivery for survival. Though many companies have introduced ERP (enterprise resource planning) systems and MRP (material requirement planning) systems, the performance of these systems seems to fall short of expectations. In this paper, the case study on introducing an APS (advanced planning and scheduling) system based on dispatching rules to a machining company and on finding a method to establish an efficient production schedule is presented. The case company has trouble creating an effective production plan and schedule, even though it is equipped with an MRP-based ERP system. The APS system is applied to CNC (computer numerical control) machines, which are key machines of the case company. The overall progress of this research is as follows. First, we collect and analyze the master data on individual products and processes of the case company in order to build a production scheduling model. Second, we perform a pre-allocation simulation based on dispatching rules in order to calculate the priority of each order. Third, we perform a set of production simulations applying the priority value in order to evaluate production lead time and tardiness of pre-defined dispatching rules. Finally, we select the optimal dispatching rule suitable for work situation of the case company. As a result, an improved production schedule leads to an increase in production and reduced production lead time.

• 한국정밀공학회지
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• 제14권7호
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• pp.39-48
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• 1997

This paper describes the process planning system of a computer-aided design of blanking and piercing for irregularly shaped sheet metal products. An approach to the system is based on knowledge-based rules. The process planning system is designed by considering several factors, such as the complexity of blank geometry, production feasibility of products, and punch profile complexity. Therefore this system which was implemented production feasibility check and strip layout module can carry out a process planning considering a production feasibility area of both internal and external features, a dimension of blanked hole, a coner and a fillet radius for irregualrly shaped sheet metal products and generate the strip layout in graphic froms. Knowledges for process planning are extracted from plasticity theories, handbooks, relevant references and empirical know- hows of experts in blanking companies. This provides powerful capabilities for process planning system of irregularly shaped sheet metal products.

• 수산경영론집
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• 제46권3호
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• pp.129-141
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• 2015

Because land based aquaculture is restricted by high investment per rearing volume and control cost, good management planning is important in Land-based aquaculture system case. In this paper master production planning was made to decide the number of rearing, production schedule and efficient allocation of water resources considering biological and economic condition. The purpose of this article is to build the mathematical decision making model that finds the value of decision variable to maximize profit under the constraints. Stocking and harvesting decisions that are made by master production planning are affected by the price system, feed cost, labour cost, power cost and investment cost. To solve the proposed mathematical model, heuristic search algorithm is proposed. The model Input variables are (1) the fish price (2) the fish growth rate (3) critical standing corp (4) labour cost (5) power cost (6) feed coefficient (7) fixed cost. The model outputs are (1) number of rearing fish (2) sales price (3) efficient allocation of water pool.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1094-1099
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• 2009

Workforce information is important in production planning because production planning requires matching a production unit's capacity to loads of assignments. However, tracking and managing workforce information such as skills and accident history is not an easy job. This paper describes a prototype database system for a workforce database system that employs RFID technology. This system tracks daily workforce production capacity on sites. A pilot project is described to explore the benefits and possibility of using radio-frequency identification (RFID) to track and manage workforce information, and is followed by the results of a survey to identify benefits. In addition to the survey identifying the benefits of the database system, the paper also presents a list of challenges through a series of interviews.

• 한국산업정보학회논문지
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• 제16권2호
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• pp.73-83
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• 2011

생산 시스템에 있어서 일정계획은 많은 비용이 투자된 생산설비 및 기계를 효율적으로 운영한다는 의미에서 매우 중요하다. 계획과 실행에서 오는 차이를 줄이기 위한 생산 시스템인 제조실행 시스템(Manufacturing Execution System : MES)의 효율성을 높이기 위해서 일정계획은 대상이 되는 작업의 특성에 적합한 일정계획 할당규칙 (Dispatching rule)에 대한 선정방법이 필요하다. 따라서 본 논문에서는 공정계획의 데이터에서 얻어지는 작업특정을 기반으로 시뮬레이션 (Simulation)을 진행하여 일정계획 할당규칙을 선정한다. 시뮬레이션을 통해 얻어진 정보를 지식기반 사례추론 방법론의 하나인 온톨로지(Ontology)로 구성함으로써 작업할당규칙 선정에 의한 적응형 일정계획 플랫폼을 개발한다. 구현하는 플랫폼은 특정 작업장에만 국한되지 않고 다양한 작업장에 적용시킬 수 있는 일정계획 시스템이라는 장점이 있다. 본 시스템 개발을 위해 온톨로지 추론 부분은 RacerPro와 Prot$\acute{e}$g$\acute{e}$를 이용하였으며, 일정계획 시뮬레이션은 JAVA와 FlexChart를 사용하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제1권2호
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• pp.70-77
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• 2009

Today, many middle-sized shipbuilding companies in Korea are experiencing strong competition from shipbuilding companies in other nations. This competition is particularly affecting small- and middle-sized shipyards, rather than the major shipyards that have their own support systems and development capabilities. The acquisition of techniques that would enable maximization of production efficiency and minimization of the gap between planning and execution would increase the competitiveness of small- and middle-sized Korean shipyards. In this paper, research on a simulation-based support system for ship production management, which can be applied to the shipbuilding processes of middle-sized shipbuilding companies, is presented. The simulation research includes layout optimization, load balancing, work stage operation planning, block logistics, and integrated material management. Each item is integrated into a network system with a value chain that includes all shipbuilding processes.

• 소성∙가공
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• 제8권6호
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• pp.591-603
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• 1999

A computer-aided process planning system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has been reported yet. Therefore, this study investigates process sequence design in deep drawing process and constructs a computer-aided process planning system for non-axisymmetric motor frame products with elliptical shape. The system developed consists of three modules. The first one os a 3-dimensional modeling module to calculate surface area for non-axisymmetric products. The second one is a blank design module that creates an oval-shaped blank with the identical surface area. The third one is a process planning module based on production rules that play the best important roles in an expert system for manufacturing. The production rules are generated and upgraded by interviewing with field engineers. Especially, drawing coefficient, punch and die radii are considered as main design parameters. The constructed system for elliptical deep drawing products would be very useful to reduce lead time and improve accuracy for production.

• 대한산업공학회지
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• 제1권2호
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• pp.27-38
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• 1975

This paper explores a quantitative decision-making system for planning production, inventories and work-force in a multi-item production system. The Multi-item Parametric Decision Rule (MPDR) model, which assumes the existence of two types of linear feed-back rules, one for work-force level and one for production rates, is basically an extension of the existing method of Parametric Production Planning (PPP) proposed by C.H. Jones. The MPDR model, however, explicitly considers the effect of manufacturing progress and other factors such as employee turn-over, difference in work-days between month etc., and it also provides decision rules for production rates of individual items. First, the cost relations of the production system are estimated in terms of mathematical functions, and then decision rules for work-force level and production rates of individual items are establised based upon the estimated objective cost function. Finally, a direct search technique is used to find a set of parameters which minimizes the total cost of the objective function over a specified planning horizon, given estimates of future demands and initial values of inventories and work-force level. As a case problem, a hypothetical decision rule is developed for a particular firm (truck assembly factory).

• 한국군사과학기술학회지
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• 제2권2호
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• pp.83-91
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• 1999

Dynamic characteristic of manufacturing stage is understood and the utilization of each machine is maximized by developing on-line dynamic CAPP system to consider the overloads in the aircraft part manufacturing line. In this paper, a scheme of production planning and scheduling system was proposed through inspection about some predeveloped CAPP system. Developed production planning and scheduling system included process planning module. After precise inspection of some FMS line schema at domestic heavy industry, optimized FMS line was applied to aircraft part manufacturing and repairing factory. By virtue of considering overloads of factory and machine through on-line dynamic CAPP system, the utilization of resources is maximized and manufacturing lead time is minimized.