• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.281-289
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• 1992

In an attempt to simulate the flows in the computer hard disk storage system, flow visualization and quantification by image processing technique were applied. Model geometry was constructed while the dynamic similitude was maintained. Circumferential velocities were mapped out in the transient spin-up phase. During the spin-up phase, fluid close to the rotating inner hub approached the solid body rotation, while the fluid in the outer region showed the velocity deficit compared to the rotating speed of the disks. Effects of presence of read/write head arm assembly between the gap were studied by changing the location of the head. The experimental results could serve as a benchmark for the alidation of numerical codes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.252-259
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• 2001

Computational study has been performed to observe the flow characteristics of combustion chamber for geometrical modification in municipal solid waste incinerator. A series of geometrical modification has been carried out as an attempt to reduce the size of recirculation zone, to obtain uniform flow field in the secondary combustion chamber and to improve the mixing of combustion gas. Two dimensional non-reacting turbulent flow has been studied as the first step to get such goals and the result of design optimization is presented. In addition, three dimensional non-reacting and reacting flow analyses were performed to verify the validity of two dimensional approach.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.825-830
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• 2001

Many techniques have been developed to evaluate the structural integrity for the traction motor with squirrel cage. However, the former approaches are not appropriate to our problems and there is no reliable specification for evaluation of squirrel cage motor. In this study, an improved boundary condition and the criteria for evaluation are proposed. Using 3-dimensional solid element, finite element model is generated. The number of meshes can be reduced by considering the symmetry of geometry. Stress analyses are carried out for three types of traction motors.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.856-860
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• 2000

Liquid ejector is widely used for power plant water pump, marine pump and transportation of solid materials. It has high working confidence and simple configuration. However, It is not easy to know performance degradation of ejectors in field. When the geometry of ejector is complicate, the diagnosis of faults is required more skillful method without disassemble. This paper gives numerical method to predict cause of $45^{\circ}$ slurry suction ejector performance degradation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.268-271
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• 2001

The die design of the liquid and semi-solid forming process is performed by CAE technology, The die design by the computer simulation has some advantages compared with the conventional method which has been performed by the designer's experiences in trials and emu. The defect zones such as porosity and shrinkage has been predicted by simulation results. The result of the numerical analysis for the proposed casting condition shows the characteristics of thixotropic flow, and was used to determine the geometry of the gating system and die cavity. The optimized production conditions were also proposed by result of computer aided engineering.

• Macromolecular Research
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• v.13 no.6
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• pp.499-505
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• 2005

Ordered mesoporous materials with a hydrothermally-stable, protozeolitic framework were prepared by exploring the direct conversion of inorganic species based on co-surfactant templating systems. To confer hydrothermal stability on the mesoporous aterials, the organic-inorganic hybrids were heat-treated in strongly basic media. Co-surfactant templating systems of cetyltrimethylammonium bromide [$C_{16}H_{13}(CH_{3})_{3}$NBr, CTAB] with 1,3,5-trim­ethylbenzene (TMB) or a nonionic block copolymer of poly(ethylene oxide )-b-poly(propylene oxide )-b-poly(ethyl­ene oxide) ($EO_{20}PO_{70}EO_{20}$) were employed to improve the hydrothermal stability of the organic-inorganic self-assembly during the solid rearrangement process of the inorganic species. The mesoscopic ordering of the pore structure and geometry was identified by X-ray diffraction, small angle neutron scattering and electron microscopy.

• East Asian mathematical journal
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• v.26 no.4
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• pp.535-551
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• 2010

In this paper, we investigate the methodology to calculate the volume of the pyramid and frustum of the pyramid that is found in Gu Jang Sel Hae and San Hak Jeong Ui(The first volume)text. Comparing and analyzing content in Korean and Chinese mathematics education textbooks that uses as a foundation the aforementioned methodology, it is proposed that in future development of mathematics education curriculum the area of solid geometry be taught in greater depth in basic study guides.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.4
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• pp.435-442
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• 2002

It is difficult to access and share design data among heterogeneous CAD systems. Usually, different CAD systems exchange the design data using a neutral format such as IGES or STEP. A prototype CAD system which uses a geometric kernel and a commercial database management system has been implemented. The prototype system used the Open Cascade geometric kernel and the commercial object-oriented database ObjectStore. STEP provides the database schema. The database can be accessed from commercial CAD systems such as SolidWorks or Unigraphics. The data access module from a commercial CAD system is developed with the CAD system's native API, ObjectStore API functions, and ActiveX.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1601-1606
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• 2004

In this paper, the unsteady behavior of the viscous flow field past an impulsively started elliptic cylinder is studied numerically. In order to analyze flow field, we introduce vortex particle method. The vorticity transport equation is solved by fractional step algorithm which splits into convection term and diffusion term. The convection term is calculated with Biot-Savart law, the no-through boundary condition is employed on solid boundaries. The diffusion term is modified based on the scheme of particle strength exchange. The particle redistributed scheme for general geometry is adapted. The flows around an elliptic cylinder are investigated for various attack angles at Reynolds number 200. The comparison between numerical results of present study and experimental data shows good agreements.

• Structural Engineering and Mechanics
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• v.5 no.6
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• pp.743-754
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• 1997

A three-dimensional constitutive modeling for reinforced concrete is presented for finite element nonlinear analysis of reinforced concrete. The targets of interest to the authors are columns confined by lateral steel hoops, RC thin shells subjected to combined in-plane and out-of-plane actions and massive structures of three-dimensional (3D) extent in shear. The elasto-plastic and continuum fracture law is applied to pre-cracked solid concrete. For post cracking formulation, fixed multi-directional smeared crack model is adopted for RC domains of 3D geometry subjected to monotonic and reversed cyclic actions. The authors propose a new scheme of decomposing stress strain fields into sub-planes on which 2D constitutive laws can be applied. The proposed model for 3D reinforced concrete is experimentally verified in both member and structural levels under cyclic actions.