• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.249-263
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• 1997

This paper addresses the parts route selection and economic design in flexible manufactuirng system (FMS). Parts are processed through several stage workstations according to operation sequences. The machine of each workstation can do multiple operation functions. And the operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing routes of parts, number of machine at each workstation, number of vehicle and makespan time. Two models are suggested. One is assumed that the operation stage of parts can be processed at the only one among several available workstations. Other is assumed that the operation stage of parts is allowed to be processed at several workstations. Parts are transported by automated guided vehicles (AGVs). The decision criteria is to minimize the sum of processing cost, travel cost, setup cost and overhead cost. The formulation of models is represented. A solution algorithm is suggested, and a numerical example is shown.

• Korean Journal of Metals and Materials
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• v.50 no.11
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• pp.809-815
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• 2012

Recently, as the interest in improving energy efficiency has grown, the demand for vehicle and machine parts that are resistant in high temperature corrosive conditions and abrasive environments has increased. Pack chromizing treatment of sintered steels is a profitable method that satisfies both corrosion resistance and low friction properties. Since austenitic stainless steels have good corrosion resistance but low mechanical hardness, if they are replaced by sintered steel parts with pack chromizing treatment, all the desirable properties such as low price, easy molding, high hardness, low frictional coefficient, and high corrosion resistance, can be obtained. The higher corrosion resistance of the chromized parts over that of the austenitic stainless steels was acquired by coating chromium carbides and a thin chromium oxides layer on the surface. Moreover, the surface morphology of chromized parts, which were composed of chromium rich phases and hardened chromium carbides by diffusing and alloying, had a peak-and-valley shape so that the dimple effect by the wrinkled morphology and high hardness induced a low friction coefficient.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.24-35
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• 2021

Due to increasing awareness on the treatment of end-of-use/life products, disassembly has been a fast-growing research area of interest for many researchers over recent decades. This paper introduces a novel lot-sizing problem that has not been studied in the literature, which is the service-parts lot-sizing with disassembly option. The disassembly option implies that the demands of service parts can be fulfilled by newly manufactured parts, but also by disassembled parts. The disassembled parts are the ones recovered after the disassembly of end-of-use/life products. The objective of the considered problem is to maximize the total profit, i.e., the revenue of selling the service parts minus the total cost of the fixed setup, production, disassembly, inventory holding, and disposal over a planning horizon. This paper proves that the single-period version of the considered problem is NP-hard and suggests a heuristic by combining a simulated annealing algorithm and a linear-programming relaxation. Computational experiment results show that the heuristic generates near-optimal solutions within reasonable computation time, which implies that the heuristic is a viable optimization tool for the service parts inventory management. In addition, sensitivity analyses indicate that deciding an appropriate price of disassembled parts and an appropriate collection amount of EOLs are very important for sustainable service parts systems.

• Journal of the Korean institute of surface engineering
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• v.42 no.5
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• pp.208-215
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• 2009

We employed atmospheric plasma to reactively remove the lubricant sprayed onto such industrial electronic parts as LCD chassis during sheet-metal forming processes and investigated basically the effect of plasma parameters on cleansing the surfaces of zinc-electroplated steel plates (EGI). Specimen prepared with some controlled amount of lubricant sprayed on their surfaces beforehand were subjected to two different kinds of atmospheric plasma, one being generated by using air and the other generated by using nitrogen (99.9% purity). Locating the plasma beams at the height range between 3.5 and 13.5 mm from the surface of each specimen and radiating for 5 to 30 seconds resulted out that the cases with a position of 3.5 mm and a duration of 5 seconds or longer showed the surfaces completely cleansed without a trace of lubricant. Furthermore we found out that the plasma generated by using simple air depicted higher cleansing ability than the other one generated by using expensive nitrogen, interestingly useful very much for industrial purposes. On another aspect, we confirmed that the drilled or cut surfaces of Zn-plated steel substrate would not be oxidized even under the influence of plasma during its cleansing process. Therefore, we could probably conclude from this fore-survey that a dry process adopting atmospheric plasma for cleansing industrial parts might be determined to become successful in terms of commercialization, cautiously.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.5
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• pp.474-479
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• 2013

Mass reduction of the machine tool movable parts is a tool for achieving lower energy demands of the machine tool operation. The realization of lightweight design in machine tool can be achieved by structural lightweight design and material lightweight design. In this study, topology optimization strategy was applied to design optimized structures of movable parts of 5 axis machining center. The weight of ram which has most significant influence on the stiffness of whole machine tool was reduced without stiffness deterioration. The redesigned optimized ram has 24.2% less weight while maintaining the same displacement caused by cutting force.

• Journal of Applied Reliability
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• v.5 no.2
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• pp.221-239
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide used electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mode caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.51-67
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide sed electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mope caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.87-99
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• 1998

This study is concerned with a problem of determining the optimal requirements level of the spare parts, especially Concurrent Spare Parts(CSP). CSP is supplied with the procurement of new equipment system, and is used to sustain the equipment without resupply during the initial coverage period. We consider this situation as a multiechelon inventory model with several bases and one depot. And we assume a equipment system which consists of many types of parts would grounded if one of the parts fail. Also this multiechelon CSP problem is considering a time-varing (dynamic) environment. We develop a computational procedure to find the optimal number of spare parts minimizing the total expected cost, while achieving the required system availability. Finally we present a simple example of suggested method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.46
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• pp.19-32
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• 1998

This paper addresses the processing route of parts and economic design in flexible manufacturing systems (FMSs) employing AGVs for Transport. Parts are processed through several workstations according to operation sequences. The machine of each workstation can do multiple operation functions. The operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing route of parts, number of machines at each workstation, number of vehicles. The model is assumed that the operation stage of parts can be processed at the only one among several available workstations. Parts are transported by automated guided vehicle system(AGVS). The decision criteria is to minimize the sum of processing cost, travel cost, operating cost. A model formulation is represented. A solution algorithm is suggested by using mathematical programming and simulation technique, and a numerical example is shown.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.198-206
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• 2005

The single sourcing policy, in which an automobile manufacturer purchases identical or similar parts from one supplier, has an advantage of scale economy. Meanwhile, multiple sourcing policy, which allows procuring similar parts from multiple suppliers, has benefits of dispersing risks and promoting competition among suppliers. This paper analyzes the procurement policies by presenting a model of the Japanese automobile parts trade. It concludes that maturity of technology involved should be taken into account besides above-mentioned factors which have traditionally been recognized. For parts produced using evolving technologies, the single sourcing enhances purchaser’s benefits because of the scale economy in learning process. In the meantime, multiple sourcing is more beneficial to the purchaser if the parts are based on mature technologies. In either policy, if the technology involved is evolving, motivating suppliers by returning a great part of cost reduction as a reward to them may eventually increase profit for the purchaser. The conclusion supports the situation where the number of suppliers is being cut down as the trend of modularization and system deliveries of parts progresses in the auto parts industry, and suggests that returning part of benefits to parts suppliers may be encouraged from the viewpoint of auto manufacturers’ own interest.