• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.140-151
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• 2013

In 2011 and 2012, Korean construction firms awarded around $ 64.5. Billion each year from the overseas market in 2011. This contract value accounted for overwhelming portion of total overseas construction contract values, and this growth is expected to continue for the next decade. However, contract scopes awarded to the Korean construction firms mainly involve detailed design and construction phases due to their competitiveness for the construction techniques. In other words, front-end-engineering-design and construction project management are not considered part of core business due to the lack of project management skills and experience. The researchers focused on development of construction sequence model required to improve construction planning and scheduling skills for the Korean construction firms. The model identifies critical work items and the sequence throughout project execution process. In addition, the researchers developed a risk evaluation method by applying fuzzy theory to the critical construction activities for the industrial plant construction projects. Developed methodology will help project practitioners to develop project schedule in a timely and effe ctive manner and evaluate project risks associated with scheduling process for the industrial plant construction projects.

• Korean Journal of Computational Design and Engineering
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• v.16 no.1
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• pp.61-72
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• 2011

As the customer's needs for diverse colors, the process of bus painting shop is becoming more and more complex. In particular, frequent changes of paint colors in each spray process require the cleaning of the painting nozzles and setting them up for the new paints, which results in increased time and cost and reduced production. This also increases environmental influences. This paper proposes, as a solution to this issue, the use of color selection field (CSF). CSF is physically a system of conveyors that are used to rearrange objects in a flow line. CSF is proposed, in this paper, to be introduced right before the spray process so that buses are better grouped according to their desired colors. Various parameters of the CSF, such as the number of conveyors and algorithms to determine the rearranged sequence of buses, have been determined by running simulations using the digital manufacturing technology, and investigating the simulation results. As an outcome of the proposed solution, the CSF system is expected to reduce approximately 30% of the nozzle cleaning cost for a Korean motor company case, which will not only benefit the company economically, but will also benefit the environment.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.3
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• pp.329-343
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• 1995

Traditionally, machining process sequence was influenced and constrained by the design information obtained from CAD data base, i.e., class of operations, geometric shape, tooling, geometric tolerance, etc. However, even though all the constraints from design information are considered, there may exist more than one way to feasibly machine parts. This research is focused on the integrated problem of operations sequencing and machine tools selection in the presence of the product mix and their production volumes. With the transitional costs among machining operations, the operation sequencing problem can be formulated as a well-known Traveling Salesman Problem (TSP). The transitional cost between two operations is expressed as the sum of total machining time of the parts on a machine for the first operation and transportation time of the parts from the first machine to a machine for the second operation. Therefore, the operation sequencing problem formulated as TSP cannot be solved without transitional costs for all operation pairs. When solved separately or serially, their mutual optima cannot be guaranteed. Machining operations sequencing and machine tool selection problems are two core problems in process planning for discretely machined parts. In this paper, the interrelated two problems are integrated and analyzed, zero-one integer programming model for the integrated problem is formulated, and the solution methods are developed using a Tabu Search technique.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.184-190
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• 2010

Recently, the polishing process using magnetorheological fluids(MR fluids) has been focused as a new ultra-precision polishing technology for micro and optical parts such as aspheric lenses, etc. This method uses MR fluid as a polishing media which contains required micro abrasives. In the MR polishing process, the surface roughness and material removal rate of a workpiece are affected by the process parameters, such as the properties of used nonmagnetic abrasives(particle material, size, aspect ratio and density, etc.), rotating wheel speed, imposed magnetic flux density and feed rate, etc. The objective of this research is to predict MRR according to the polishing conditions based on the multiple regression analysis. Three polishing parameters such as wheel speed, feed rates and current value were optimized. For experimental works, an orthogonal array L27(313) was used based on DOE(Design of Experiments), and ANOVA(Analysis of Variance) was carried out. Finally, it was possible to recognize that the sequence of the factors affecting MRR correspond to feed rate, current and wheel speed, and to determine a combination of optimal polishing conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.914-923
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• 2002

Recently, there has been considerable interest in micro gyroscopes made of silicon chips. It can be applied to many micro-electro-mechanical systems (MEMS): devices for stabilization, general rate control, directional pointing, autopilot systems, and missile control. This paper shows how the mechanical design of the gyroscope can be done using axiomatic design, followed by the application of the Taguchi robust design method to determine the dimensions of the parts so as to accommodate the dimensional variations introduced during manufacturing. Functional requirements are defined twofold. One is that the natural frequencies should have fixed values, and the other is that the system should be robust to large tolerances. According to the Independence Axiom, design parameters are classified into a few groups. Then, the detailed design process is performed fellowing the sequence indicated by the design matrix. The dimensions of the structure are determined to have constant values fur the difference of frequencies without consideration of the tolerances. It is noted that the Taguchi concept is utilized as a unit process of the entire axiomatic approach.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.1
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• pp.38-47
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• 2014

This paper describes the application of discrete event systems theory to the design of an automated laboratory system. Current automated laboratory systems typically consist of several interacting processes that must be carefully sequenced to avoid any possible process conflicts. Discrete Event Systems (DES) theory and Supervisory Control Theory (SCT) can be applied together as effective methods of modeling the system dynamics and designing supervisory controllers to precisely sequence the many processes that such systems might involve. Classical approaches to supervisory controller design tend to result in complex controller structures that are difficult to implement, maintain, and upgrade. In this paper, a new approach to designing supervisory controllers for automated laboratory systems is introduced. This new approach uses a modular controller structure that is easier to implement, maintain, and upgrade, and deals with "state explosion" issues in a novel and efficient way.

• IE interfaces
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• v.16 no.2
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• pp.268-279
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• 2003

This paper presents critical steps in building client/server application with UML and Visual Basic, which are derived from the implementation case of a typical order processing system. To begin with, we briefly review the software architecture, the diagrams and the object-oriened building process in the UML. In the inception phase, it is critical to define the project charter, to draw use case diagrams, and to construct a preliminary architecture of the application. In the elaboration phase, it is critical to identify classes to be displayed in the class diagram, to develop user interface prototypes for each use case, to construct sequence diagram for each use case, and finally to design an implementation architecture. Steps to construct implementation architecture are given. In the construction phase, it is critical to design both the database and components. Steps to design these components are described in detail. Additionally the way to create the Internet interface is suggested.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.452-460
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• 2001

Most of researches of tolerance optimization have used a simple sum of tolerance-cost functions with several constraint equations as an optimization model. However, if there is a machining sequence with more than one processes to complete a part, and machining failure, i.e., out-of-tolerance occurs at one of the intermediate processes, the tolerance-cost of this process should be added by the machining cost of all the previous processes already completed on the part. In this study, an accumulated scrap cost model(ASCM) is proposed considering the scrapped machining cost, and applied to a simple assembly example. The result of tolerance optimization using ASCM is compared with that of using a traditional optimization model to confirm its effectiveness.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.353-360
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• 2001

Electro Electric Systems Division of HHI is developing new series of models for industrial mid/compact size motors to satisfy the demand of costumers. Various essential technologies are required for motors to support design technology on design and development stage. Conventional motors have several things to analyze for mechanical strength and structural deformation during manufacturing process or operation. Therefore, the manufacturing cost will be reduced and the danger of accident during operation will be prevented by recognizing and revising the problems prior to actual manufacturing and operation. 112 Frame motor (3.7 kW) has been analyzed for this study and the basic analysis technology is eventually developed by analyzing other models gradually (sequence of 112, 135, 250, 200, 280, 225, 160, 180 Frame motors). Then, the developed technologies are established as main factors to support the motor design technology and competitive motors will be manufactured to satisfy the costumers.

• International Journal of High-Rise Buildings
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• v.3 no.4
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• pp.311-323
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• 2014

This paper introduces recent applications of three-dimensional building/construction data modeling (3D) and building information modeling (BIM) to large-scale complex building construction projects in Japan. Recently, BIM has been utilized as a tool in construction process innovation through planning, design, engineering, procurement and construction to establish a front-loading-type design building system. Firstly, the background and introduction processes of 3D and BIM are described to clarify their purposes and scopes of applications. Secondly, 3D and BIM applications for typical large-scale complex building construction projects to improve planning and management efficiency in building construction are presented. Finally, future directions and further research issues with 3D and BIM applications are proposed.