• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.437-438
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.313-314
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1059-1060
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• 2013

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.174-181
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• 2004

Recently, many studies have been undergoing to reduce working time in field of machine tool. There are two ways of reducing working time to reduce actual working time by heighten spindle speed and to reduce stand-by time by shortening tool exchange time. Auto tool changer belongs to latter case. Fixed address type auto tool changer can store more number of tools in small space than magazine transfer Ope and can shorten tool exchange time. This study focuses on the topology optimization to reduce the weight of the fixed address type ATC. The optimization program using a real number coding genetic algorithm is developed and is applied to the 10-bar truss optimization problem to verify the developed program. And, it is shown that the developed program gives better results than other methods. Finally, The developed program applied to optimize the fixed address type ATC.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.22-29
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• 2004

As a result of high integration of semiconductor device, the global planarization of multi-layer structures is necessary. So the chemical mechanical polishing(CMP) is widely applied to manufacturing the dielectric layer and metal line in the semiconductor device. CMP process is under influence of polisher, pad, slurry, and process itself, etc. In comparison with the general CMP which uses the slurry including abrasives, fixed abrasive pad takes advantage of planarity, resulting from decreasing pattern selectivity and defects such as dishing & erosion due to the reduction of abrasive concentration especially. This paper introduces the manufacturing technique of fixed abrasive pad using hydrophilic polymers with swelling characteristic in water and explains the self-conditioning phenomenon. And the tungsten CMP using fixed abrasive pad achieved the good conclusion in terms of the removal rate, non-uniformity, surface roughness, material selectivity, micro-scratch free contemporary with the pad life-time.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.293-301
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• 2022

Direction of arrival (DOA) estimation of space signals is a basic problem in array signal processing. DOA estimation based on the multiple signal classification (MUSIC) algorithm can theoretically overcome the Rayleigh limit and achieve super resolution. However, owing to its inadequate real-time performance and accuracy in practical engineering applications, its applications are limited. To address this problem, in this study, a DOA estimation algorithm with high parallelism and precision based on an analysis of the characteristics of complex matrix eigenvalue decomposition and the coordinate rotation digital computer (CORDIC) algorithm is proposed. For parallel and single precision, floating-point numbers are used to construct an orthogonal identity matrix. Thus, the efficiency and accuracy of the algorithm are guaranteed. Furthermore, the accuracy and computation of the fixed-point algorithm, double-precision floating-point algorithm, and proposed algorithm are compared. Without increasing complexity, the proposed algorithm can achieve remarkably higher accuracy and efficiency than the fixed-point algorithm and double-precision floating-point calculations, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.25-30
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• 2001

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.212-220
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• 2002

The finishing process for die and mold manufacturing is very important because it influences the final quality of products. Injection molds need higher quality surface than general purpose dies and molds. Conventional polishing can not make mold surface down to nanometer roughness efficiently because of their loading and glazing. This paper focused on the development of fixed abrasive pad using water swelling mechanism of polymer binder network. Self-conditioning was recognized as the long term polishing stabilization tool without any loading or glazing because water makes fixed abrasives free by swelling of the pad. Consequently, stable nano-polishing process has been applied on the injection mold, from the experimental results with polished surface roughness of Ra 15.1nm on STD-11 die steel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1150-1153
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• 2003

Recently, Many studies have been undergoing to reduce a working time in a field of machine tool. There are two ways of reducing working time; to reduce actual working time by heighten spindle speed and to reduce stand-by time by shortening tool exchange time. Automatic tool change system belongs to the latter case. Fixed address type automatic tool change system that is being developed in this study can store more number of tool in small space than magazine transfer type automatic tool changer as well as shorten tool exchange time. In this paper, a simplified equivalent model of finite element method in order to analyze frame structure of fixed address type automatic tool change system is presented.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.123-131
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• 1995

다주파수 입력을 갖는 강한 비선형 시스템의 유사주기 (quasi-periodic) 해를 해석하기 위하여 개선된 고정 점법(FPA:Fixed Point Alogrithm)을 개발하였다. 안정성 및 천이 특성을 판별하기 위하여 사용되어지는 Floquest 지수인 해석적 자코비언을 구하기 위하여 Poincare 맵상에서 이산 적분법을 새로이 고안, 사용하였다. 본 방법의 우수성을 입증하기 위하여 2개의 주파수 입력을 갖는 선형 시스템과 비선형 시스템을 예로 사용하였다. 본 방법을 이용하여 비선형 시스템에서 발생한 복잡한 chaos 현상을 체계적으로 해석하였다.