• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1215-1220
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• 2008

To obtain the shape of the free surface more accurately, computations are carried out by a finite volume method using unstructured meshes and an interface capturing method. Free-surface flow, which is very important in the fields of ship and marine engineering, is numerically simulated for flows of both water and air. Control volumes are used with an arbitrary number of faces and allows a local mesh refinement. The integration is of second order, with a midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation. The solution method of pressure-correction type solves sequentially equations of momentum, continuity, conservation, and two-equations turbulence model. Comparison are quantitatively made between the computation and experiment in order to confirm the solution method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.960-972
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• 1992

This paper deals with the development of expert system in distribution system which combined with graphic user interface. The proposed expert system can recognize and adjust to the system change, and includes the rule bases of security monitoring. Also it provides load transfer algorithm for efficient load distribution. The graphic user environment for expert system is implemented in the mouse-oriented user interface with overlapped window functions and pull-down menus. Therefore, the developed graphic integrated expert system can afford to assist system operators very conveniently through the various graphic function in proposing an optimal plan of load transfer for fault restoration and outage schedule.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.100-103
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• 1996

Presented in this study is an algorithmic procedure to obtain polyhedral model from a compound surface. The compound surface in this study denotes a collection of trimmed surfaces without topological relations. The procedure consists of two main modules: CAD data interface, and surface conversion to polyhedral model. The interface module gets geometric information from CAD databases, and makes topological information by scanning the geometric information. We are investigating CATIA system as a data source system. In the surface conversion module, a shell(compound surface with topological information) is approximated to a triangular-faceted polyhedral surface model through node sampling and triangulation steps. The obtained polyhedral model should obey the vertex-to-vertex rule and meet tolerance requirements. Since the polyhedral model has a simple data structure and geometry processing for it is very efficient and robust, the polyhedral model can be used in various applications, such as surface rendering in computer graphics, FEM model for engineering analysis, CAPP for surface machining, data generation for SLA, and NC tool path generation.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.2
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• pp.119-132
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• 1993

This paper deals with the development of an expert process design system interfaced with CAD for porismatic parts in injection mold manufacture. The developed CAD/CAPP system consists of two modules such as CAD interface module and process design module. Parts are represented using AutoCAD system on the IBM PC/AT. CAD interface module recognizes form features and manufacturing features of the part using form feature recognition algorithm and manufacturing feature recognition rule base. Process design module selects operations and determines machine tools, cutting tools and operation sequencing by using knowledge base which is acquired from expert process planners. A case study is implemented to evaluate feasibilities of the function of the proposed system. The CAD/CAPP system can improve the efficiency of process design activities and reduce the time required for process design.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.174-180
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• 2010

Conductive and radiative thermal model configurations of an imager of a geostationary satellite are presented. A two-plane method is introduced for three dimensional conductive coupling which is not able to be treated by thin shell plate thermal modeling technique. Especially the two-plane method is applied to massive matters and PIP(Payload Interface Plate) in the imager model. Some massive matters in the thermal model are modified by adequate correction factors or equivalent thickness in order to obtain the numerical results of thermal modeling to be consistent with the analytic model. More detailed nodal breakdown is specially employed to the object which has the rapid temperature gradient expected by a rule of thumb. This detailed thermal model of the imager is supposed to be used for detailed analyses and test predictions, and be correlated with the thermal vacuum test results before final in-flight predictions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.101-107
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• 2008

A composite mechanics for discontinuous fiber reinforced polymer matrix composites(PMC) is analysed in order to predict fiber axial stresses. In continuum approach. frictional slip which usually takes place between fibers and polymers is accounted to derive PMC equations. The interfacial friction stress is treated by the product of the coefficient of friction and the compressive stress norma1 to the fiber/matrix interface. The residual stress and the Poisson's contraction implemented by the rule of mixture(ROM) are considered for the compressive stress normal to the fiber/matrix interface. In addition. the effects of fiber aspect ratio and fiber volume fraction on fiber axial stresses are evaluated using the derived equations. Results are illustrated numerically using the present equations with reasonable materials data. It is found that the fiber axial stress in the center region shows no great discrepancy for different fiber aspect ratios and fiber volume fractions while some discrepancies are shown in the fiber end region.

• Journal of Adhesion and Interface
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• v.3 no.1
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• pp.43-51
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• 2002

Advanced adhesive technologies and demanding applications of adhesive joints can no longer be developed successfully by the traditional "trial and error" approach. Appropriate technical solutions require reference to a reliable basis of well-established scientific knowledge about the elementary mechanisms of adhesion (i.e. the 'fundamental adhesion') as they are responsible for the capability of the compound w transmit mechanical force between the adhesive and the substrate surface (i.e. the 'practical adhesion'). Adhesion mechanisms also influence the formation of polymer structure in the adhesive and the resulting macromolecular dynamics in the interphase that is formed in the adhesive near to the substrate. These manifold molecular factors rule the macroscopic behaviour of an adhesive bond line in terms of mechanical and other physical properties as well as in terms of durability. This paper reviews the level of refinement that understanding of fundamental adhesion has achieved up to now.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.1
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• pp.105-115
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• 1991

This paper describes an integrated CAD and CAPP system for prismatic parts of injection mold which generates a complete process plan automatically from CAD data of a part without human intervention. This system employs Auto CAD as a CAD model and GS-CAPP as an automatic process planning system for injection mold. The proposed CAD/CAPP system consists of three modules such as CAD data conversion module, manufacturing feature recognition module, and CAD/CAPP interface module. CAD data conversion module transforms design data of AutoCAD into three dimensional part data. Manufacturing feature recognition module extracts specific manufacturing features of a part using feature recognition rule base. Each feature can be recognized by combining geometry, position and size of the feature. CAD/CAPP interface module links manufacturing feature codes and other head data to automatic process planning system. The CAD/CAPP system can improve the efficiency of process planning activities and reduce the time required for process planning. This system can provide a basis for the development of part feature based design by analyzing manufacturing features.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.704-706
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• 1991

In CAD/CAM system, many efforts are made to automate the converting process from drawling information to manufacturing Information. The most difficult step In this procedure is utilizing 2 dimensional drawing information In order to formulate 3 dimensional w&ling information. This paper emphasizes to mWe automatically series of convertirg steps which provide 3 dimensional wire frame, surface and solid modeling using feature recognition rules. With the standardization of design process and the recognition rule as preceding steps, it shows a good application tool to interface the design and manufacturing procedures in PC-Level CAD/CAM system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.76-79
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• 1997

In this study, an elasto-plastic finite element code, ESFORM, was developed to analyze sheet stamping processes. A formulation of 4-node degenerated shell element was implemented in the code. Workpiece materials were assumed to have planar anisotropy, and governed by associated flow rule. Explicit time integration method was employed to save computation time and reduce the required computer memory. Penalty method was used to describe interface behavior between workpiece and rigid die. Deep drawing of square cup and front finder stamping processes were simulated by ESFORM>