• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.57-64
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• 2006

High speed milling experiment on the hardened mold steel (CALMAX at hardness of HRC 55) is carried out using small diameter ball endmills. Tool lift and wear characteristics under the various machining parameters are investigated Effect of dynamic runout on the wear of the tool is also studied. For most of the cases, catastrophic chipping of tool edge is not observed and uniformly distributed wear on the flank surface of the tool is obtained. It is found that lower rate of tool wear is obtained as the cutting speed is increased. Also, high pick feed rate is found to be more favorable in terms of the tool wear and material removal rate.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.212-221
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• 2003

In order to reduce the lead-time and cost, the technology of rapid prototyping (RP) has been widely used. A new rapid prototyping process, transfer-type variable lamination manufacturing process by using expandable polystyrene foam (VLM-ST), has been developed to reduce building time, apparatus cost and additional post-processing. At the same time, VLM Slicer, the CAD/CAM software for VLM-ST has been developed. In this study, algorithms for accuracy improvement of VLM-ST, which include offset and overrun of a cutting path and generation of a reference shape are developed. Offset algorithm improves cutting accuracy, overrun algorithm enables the VLM-ST process to make a shape of sharp edge and reference shape generation algorithm adds additional shape which makes off-line lamination easier. In addition, proposed algorithms are applied to practical CAD models for verification.

• Transactions of Materials Processing
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• v.17 no.2
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• pp.107-112
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• 2008

In order to investigate the residual stress evolution during the leveling process of hot rolled high strength coils for cold forming, the in-plane residual stress of plate sampled at SPM, rough leveler and finish leveler were measured by cutting method. Residual stress was localized near the edge of plate. As the thickness of plate was increased, the size of residual stress region was expanded. The gradient of residual stress within the plate was reduced during the leveling process. But the residual stress itself was not removed completely within the ranges of tested conditions. The exact camber of cut plate was able to be predicted by the measurement of residual stress distribution after leveling of the plate.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.427-431
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• 2011

In general, hot stamped component is trimmed by costly and time consuming laser cutting when the material strength is over 1,500MPa. The aim of this work was to demonstrate that the trimming die life is improved and the trimming load is decreased by lowering the strength of the region to be trimmed. The model employed in this study was a hat shape, similar to the cross section of many hot stamped products. FE-analysis of hot stamping process was performed to evaluate the effect of tool shape on cooling rate at the area to be trimmed. The best tool shape was thus identified, which created slower cooling and lower hardness at the region to be trimmed. The wear at the cutting tool edge was also reduced.

• Transactions of Materials Processing
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• v.12 no.3
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• pp.208-213
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• 2003

The methodology to design initial blanks considering the reduction of both springback and flange trimming amounts is studied. Three dimensional forming analysis of a trial blank Is first carried out using FEM and the tentative Initial blank shape is then determined by cutting the outer edge of the trial blank whose shape is nearly matched with the trimming line. During the shaping the blank edge, tile movement of blank outer line is described with random variables to reduce the sensitivity of initial blank geometry. After performing 2-D FEM forming and springback simulations for selected sections and optimizing the trimming and springback amounts in terms of section length of the blank, the initial blank is finally determined. In order to see tile springback reduction in the initial blank determined by the proposed method, a stepped s-rail is stamped and the sppingback is measured. The springback of newly designed initial blank of stopped s-tail is tremendously reduced.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.97-105
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• 2002

The use of rapid prototyping (RP) has reduced time to market, cut total costs and improved product quality by giving design and manufacturing teams the opportunity to verify and fine tune designs before committing them to expensive tooling and fabrication. In order to improve their unique characteristics according to the working principles, Variable Lamination Manufacturing process (VLM-ST) and corresponding CAD/CAM software (VLM-Slicer) is developed. The objective of this study is to improve the accuracy of VLM-ST process, and it can be done by offset fur cutting error correction, cutting path overrun fur sharp edge and reference shape generation for off-line stacking. It has been shown that, through the verification experiments for given practical shapes, the proposed algorithms are effective for diverse categories of three-dimensional shapes.

• Journal of the military operations research society of Korea
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• v.36 no.1
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• pp.103-121
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• 2010

As a cutting edge technology intensive value-added business, the defense industry is jumping into a new engine of a national growth. Also, the defense industry export is recognized not only as the field to activate the Korean economy but also as an important field to create the national brand value. However, though the consensus on the importance of defense industry export helps achieve the remarkable performance in reality, the rate of increase in the budget for national defence is slowing down gradually, and the investment in R&D is not so big, and there are a lot of drawbacks with the management of core technology and the development of cutting edge weapon system. Accordingly, this thesis tried to find the leverage to make the structure of defense industry export work normally after analyzing the systematical structure of defense industry export to understand its characteristics. Also, through the process to make the leverage a strategy, the thesis tried to present the optimal direction of policy to join the ranks of the advanced countries in defense industry export.

• Journal of Information Technology Applications and Management
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• v.12 no.1
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• pp.91-109
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• 2005

The reason why modern companies adopt cutting-edge technologies aggressively is mainly due to maintain the competitiveness in this cut-throat business environment. One of the most important technology factors to maintain the competitiveness in this modern e-business era is how to adopt and apply information technology(IT). More and more companies are trying to implement their management strategies by applying IT, and therefore it is now important to understand IT strategy. Many of leading-edge companies believe that they need a structured and systematic approach, called ISP (Information Strategy Planning), to secure competitive IT capability, and heavily invest their resources to achieve the excellence in IT. However, eventual effects from those investments are not always proportional since every investment has its own investment parameters and objectives. In this research, we tried to develop a systematic model to verify the relation between the business competitiveness and ISP. First, in order to include the factor 'ISP', we modified the models suggested by past research results, and then analyzed the influences from IT investments and quality of ISP on the IT excellence of businesses. To prove the validity of the developed model, several sets of surveys were performed for 66 companies in various industries including electronics, manufacturing, finance, and service. The result of the research has shown that the quality of ISP impacts more on a corporate's business competitiveness, but none on business output.

• Design & Manufacturing
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• v.9 no.2
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• pp.6-9
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• 2015

The objective of manufacturing knowledge sharing platform is to convert the production experience like a worker's know-how into quantitative values, to construct database of the process technologies and to share the technologies systematically via web portal service. In addition, the knowledge sharing platform contains the total production processes of automobile and mobile products such as information of experts, facilities, and cutting-edge R&D outputs. Automobile, telecommunication mobile, and semiconductors account for a large amount of Korea's export industry rate. These industries need production technology which is a result of converting worker's know-how and R&D. Manufacturing knowledge portal aims to enable transforming production experience such as worker's know-how into standardized form for constructing database and sharing technologies systematically. Manufacturing knowledge portal can contribute to small and mid-sized manufacturing companies with further improvements.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.160-166
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• 2015

Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is $5.4{\mu}m$ noted at the frequency of 40 kHz. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.