Kyu-Kab Cho

An automated welding operation planning system for block assembly in shipbuilding

Abstract The block assembly process is one of the most important manufacturing processes for shipbuilding. Since block is composed of several steel plates and steel sections with predetermined shapes according to ship design, the welding operation planning to construct a block is a critical activity for shipbuilding, but this activity has traditionally been experience based. Thus, it is required to develop an automated welding operation planning system to assemble blocks. This paper describes the development of an automated welding operation planning system for block assembly in shipbuilding. Based on the information about parts, topological relationship between parts and assembly sequences for block, the developed system performs the determination of welding postures, welding methods, welding equipment and welding materials. The developed system implemented successfully for real blocks constructed in shipyard.

An Automatic Process-Planning System for Block Assembly in Shipbuilding

Abstract Block assembly in shipbuilding is mainly concerned with cutting and welding operations to construct a block. A block is composed of several steel plates and sections with various sizes and shapes. Process planning for block assembly is to generate cutting and bending operation plans, assembly processes and sequences, and welding operation plans to construct a block. This paper deals with the development of an automatic process planning system for block assembly in shipbuilding. Part assembly graph that is a semantic network type of representation scheme for block structure is proposed and used to represent block information. The approaches adopted are case-based reasoning for block assembly process planning and rule-based reasoning for process planning of cutting and welding operations. The prototype system has been implemented and verified using real blocks in the block assembly shop.

Optimal tool selection for pocket machining in process planning

In process planning for pocket machining, selection of tool size, tool path, cutting width at each tool path, and calculation of machining time are very important factors for optimal process planning. The tool size is the most important factor because the other factors depend on tool size. Therefore, the optimal selection of tool size is the most essential task in pocket machining process planning. This paper presents a method for selecting optimal tools for pocket machining for the components of injection mold. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.

System analysis of a multi-product, small-lot-sized production by simulation: a Korean motor factory case

In this article, a simulation model of an existing motor production line is developed to identify system parameters to improve the system performances such as facility utilization, flow time, and buffer sizes (work-in-process inventories). System parameters investigated include dispatching rules, setup time reduction, overwork, demand increase, and productivity improvement. The simulation results have been applied to the development of a new layout. The model has been developed using SIMAN simulation language which has been demonstrated to be a powerful tool to simulate complex manufacturing systems.

Development of DVD for the Next Generation by Axiomatic Approach

Abstract DVD(Digital Versatile Disk) is a media for data storage device for high density and high speed information processing. Therefore higher rotational speed and better accuracy in optical pick-up are required compared with the existing devices. These functional requirements must be satisfied in order for DVD to keep its status as the high capacity data storage device. This paper first evaluates the currently developed DVD, and also provides methods to improve the current design using an Axiomatic Approach which is an excellent tool in deriving a new design as well as evaluating an existing one.

A knowledge-based process planning system for injection mold

Abstract The goal of this study is to develop a knowledge-based process planning system interfaced with design for injection mold. Mold parts are interactively designed by using feature-based design approach, and then a part feature database is created through a data conversion module. Attribute information of the database is used as an input for the expert process design module and the standard time estimation module of the knowledge-based process planning system developed in this study. In this developed system, decision making of process design is performed by rules which were acquired from experienced process planners through interviews, and machining operation time is estimated by using empirical formulas derived from the actual shop floor data. A case example of split cavity plate is used to demonstrate the system performance.

An integration of feature recognition and process planning functions for turning operation

Abstract This paper deals with the development of a Computer Aided Process Planning(CAPP) system interfaced with CAD for turning operation. The developed system performs CAD interfaced feature recognition from part geometry database, and the decision procedures for process planning functions such as process and operation selection, machine tool selection, setup planning and operation planning. The system runs under personal computer environments and AutoCAD is employed as CAD system and Turbo-C is used for the decision procedures. A case study is performed to evaluate the performance of the system.

A heuristic lot sizing algorithm for a GT cell

Abstract In this paper, a multi-group single-level capacitated dynamic lot sizing problem for a GT cell is formulated as a mixed integer programming problem. In the model, group setup time, part setup time, and the effects of setup time on production capacity are discussed in detail. A two-stage heuristic lot sizing algorithm consisting of a cost reduction stage and a feasibility enforcement stage in developed and illustrated by a numerical example. The performance of the proposed algorithm is evaluated using the numerical experiment for various demand patterns and values of cost parameters.