• Coupled systems mechanics
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• v.4 no.3
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• pp.263-277
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• 2015

This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case, the coupling of these methodologies is recommended, allowing exploring their respective advantages. Here, frequency domain analyses are focused and an iterative FEM-BEM coupling technique is considered. In this iterative coupling, each sub-domain of the model is solved separately, and the variables at the common interfaces are iteratively updated, until convergence is achieved. A relaxation parameter is introduced into the coupling algorithm and an expression for its optimal value is deduced. The iterative FEM-BEM coupling technique allows independent discretizations to be efficiently employed for both finite and boundary element methods, without any requirement of matching nodes at the common interfaces. In addition, it leads to smaller and better-conditioned systems of equations (different solvers, suitable for each sub-domain, may be employed), which do not need to be treated (inverted, triangularized etc.) at each iterative step, providing an accurate and efficient methodology.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.90-101
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• 1996

Determination of assembly sequence of components is a key issue in assembly operation. Although a number of articles dealing with assembly sequence determination have appeared, an efficient and general methodology for complex products has yet to appear. The objective of this paper is to present the problems and models used to generate assembly sequence from design data. An essential idea of this research is to acquire a finite number of voxels from any complex geometric entity, such as 3D planar polygons, hollow spheres, cylinders. cones, tori, etc. In order to find a feasible assembly sequence, the following four steps are needed: (1) The components composing of an assembly product are identified and then the geometric entities of each component are extracted. (2) The geometric entities extracted in the first step are translated into a number of voxels. (3) All the mating or coupling relations between components are found by considering relations between voxels. (4) The components to be disassembled are determined using CCGs (Component Coupling Graph).

• The KIPS Transactions:PartD
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• v.12D no.4 s.100
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• pp.609-616
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• 2005

The component-based development methodology becomes famous as the reuse technology to improve the high productivity of software development. It is necessary component metrics for component-based systems, because the designed components should be measurable to improve the quality of the software. Therefore this paper propose a coupling metric for component design which is reflected in characteristics of component. This paper suggest a case study and comparative analysis result about conventional metrics to verify the accuracy of our coupling metric. The Uoposed coupling metric measure the quality of components accurately and satisfies necessary conditions of coupling metric suggested by Briand and others.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.575-582
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• 2002

A new coupling method of Element-Free Galerkin Method(EFGM) and Boundary Element Method(BEM) using the domain decomposition method is presented in this paper. This proposed methodology is that the problem domain is decomposed into sub-domains being modeled by the EFGM and BEM respectively and the respective EFGM and BEM domains share a partially overlapped region over an entire domain. Then, the each sub-domain is separately computed and the variables on common region are iteratively updated until converging. It is an important note that in the developed coupling method, there is no need to combine the coefficient matrices of EFGM and BEM sub-domains, in contrast with the other conventional coupling methods. In the first part of this paper, a theory of EFGM and BEM is summarized, and then a brief introduction of domain decomposition method is described. Then, a new coupling method is presented. Also, patch test and Some numerical examples are studied to verify stability, accuracy and efficiency of the proposed method, in which numerical performance of the method is compared with that of conventional method such as EFGM-BEM variational coupling method, EFGM and BEM.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.62.1-62
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• 2002

• Korean Management Science Review
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• v.11 no.2
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• pp.65-77
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• 1994

One of the major issues in the implementation and maintenance of CIM databases is the sharing and exchange of information among the heterogeneous databases. This paper addresses some architectural aspects for integrating the heterogeneous multi-databases using knowledge-based expert systems. we propose a loosely integrated coupling system between databases and knowledge-based expert systems. Especially we suggest the architectural aspects of such a coupling methodology. we also present the structure and knowledge representation scheme for the proposed knowledge-based expert system. A prototype example is included to illustrate the framework and its mechanism for implementation.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.59-63
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• 2007

We propose a controller design analysis for a cross-coupling control system, which is essential for achieving high contouring accuracy in multi-axis CNC systems. The proposed analysis combines three axial controllers for each individual feed drive system together with a cross-coupling controller at the beginning of the design stage in an integrated manner. These two types of controllers used to be separately designed and analyzed since they have different control objectives. The proposed scheme is based on a mathematical formulation of a three-dimensional contour error model and includes a stability analysis for the overall control system and a performance analysis in terms of contouring and tracking accuracy at steady state. A computer simulation was used to demonstrate the validity of the proposed methodology. The performance variation was investigated under different operating conditions and controller gains, and a design range was elicited that met the given performance specifications. The results provide basic guidelines in systematic and comprehensive controller designs for multi-axis CNC systems. A cross-coupling control system was also implemented on a PC-based three-axis CNC testbed, and the experimental results confirmed the usefulness of the proposed control system in terms of contouring accuracy.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.351-354
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• 2002

A number of bis-2-oxo amide triacylglycerol analogues, a recently reported potent human gastric lipase inhibitor and its new analogues, have been prepared starting from 1,3-dibromo-2-propanol utilizing acyl cyanophosphorane methodology as a key step in a convergent manner. The key coupling reaction has been accomplished at -$78^{\circ}C$ between 1,3-diamino-2-propanol derivative and the labile diketo nitriles, derived from acyl cyanotriphenylphosphoranes upon oxidizing with $O_3$, under mild condition in moderate yields.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.1
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• pp.49-57
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• 2002

Including RF Package inductance, substrate coupling through conductive silicon(Si)-substrate is modeled and quantitatively characterized. 2-port substrate coupling model is extended for the characterization of multi-port substrate coupling between digital circuit block and analog/RF circuit block. Furthermore, scalable parameter extraction model is developed. Multi-port substrate coupling can be investigated by linearly superposing a frequency-dependent 2-port substrate coupling model using scalable parameters. In addition, Substrate coupling including RF package inductance effect is quantitatively investigated. It is shown that package effect increases substrate coupling and shifts a characteristic frequencies(i.e., poles) to the higher frequency range. The proposed methodology can be efficiently used to the mixed-signal circuit performance verification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.137-138
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• 2006

This paper proposes a controller design analysis for three-axis CNC systems considering both contouring and tracking performance. The proposed analysis inclusively combines axial controllers for each individual feed drive system together with cross-coupling controller at the beginning design stage as an integrated manner. These two controllers used to be separately designed and analyzed since they have different control objectives. The proposed scheme includes a stability analysis for the overall control system and a performance analysis in terms of contouring and tracking accuracy. Computer simulation is performed and the results show the validity of the proposed methodology.