• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.119-128
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• 1998

In this paper, nonsteady state shaped drawing process has been investigated using the three-dimensional rigid-plastic finite element method. In order to analyze the shaped drawing process, a method to define straight converging die considering straight die part, die radius part and bearing part has been proposed. In addition, the modeling of initial billet and the generation procedure of mesh system have been suggested. The three-dimensional rigid-plastic finite element simulation has been performed for a square sectional drawing process and its result has been confirmed in comparison with the existing experimental one. Also, for the same process conditions, the effect of perimeter ratio in the shaped drawing process has been investigated.

• Ocean and Polar Research
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• v.27 no.1
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• pp.35-44
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• 2005

The bathymetric and gravity data were obtained in 2001 and 2003 during a survey of seamounts in the northwest of the Marshall Islands, western Pacific. The study areas are located in the Pigafetta Basin which is the oldest part of the Pacific plate and in the Ogasawara Fracture Zone which formed from the spreading ridge between the Izanagi and Pacific plates in the Jurassic. The densities of seamounts and the elastic thickness values of the lithosphere are calculated by using three-dimensional flexure modeling considering the constant sediment layer in the infinite plate model. Very low elastic thickness values (5km), relatively young seamounts, and old lithosphere in the east study area suggest the possibility of the rejuvenation of lithosphere by widespread volcanisms, whereas the elastic thickness values (15km), relatively old seamounts, and young lithosphere of the west study area are suitable for a simple cooling plate model of $300-600^{\circ}C$ isotherm. The gravity residuals of OSM6-1 and OSM6-2 suggest the possibility of different load density or elastic thickness. Relatively older OSM6-2 formed on the younger lithosphere with relatively thin elastic thickness, while younger OSM6-1 on the older lithosphere with relatively thick elastic thickness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.277-283
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• 2016

Recently, the interests in three-dimensional design and BIM(Building Information Modeling) are increasing in civil engineering sector and the researches about three-dimensional design and quantity take-off methods for civil engineering structures have been conducted. However, these studies are just carried out the 3D design and quantity calculation of civil structures on the road or railway such as bridges and tunnels. The study on the quantity take-off methods and the evaluation of calculated results on the earth works should be performed in more detail. Based on these backgrounds in mind, the study was conducted the three-dimensional road design and evaluated the quantity take-off results on the earth works using 3D calculation method(average end area method, prismoidal method and composit method). The calculated quantity from composit method showed about 5% error of measuring efficiency than the average end area method, and when reporting the quantity calculation of earth works, it is necessary to specify the calculation method using quantity take-off of earth works.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.2
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• pp.80-87
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• 1998

Since groundwater flow paths have one of the major roles to transport the radioactive nuclides from the radioactive waste repository to the biosphere, the discrete fracture network model is used for the rock block scale flow instead of the porous continuum model. This study aims to construct a three dimensional discrete fracture network to interpret the groundwater flow system in the study site. The modeling work includes the determination of the probabilistic distribution function from the fracture geometric and hydraulic parameters, three dimensional fracture modeling and model calibration. The results of the constant pressure tests performed in a fixed interval length at boreholes indicate that the flow dimension around boreholes shows mainly radial to spherical flow pattern. The fracture transmissivity value calculated by Cubic law is 6.12${\times}$10$\^$-7/ ㎡/sec with lognormal distribution. The conductive fracture intensity estimated by FracMan code is 1.73. Based on this intensity, the total number of conductive fractures are obtained as 3,080 in the rock block of 100 m${\times}$100 m${\times}$100 m.

• Journal of the Korea Computer Graphics Society
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• v.3 no.2
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• pp.27-34
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• 1997

3-D image modeling is in high demand for automated visual inspection and non-destructive testing. It also can be useful in biomedical research, medical therapy, surgery planning, and simulation of critical surgery (i.e. cranio-facial). Image processing and image analysis are used to enhance and classify medical volumetric data. Analyzing medical volumetric data is very difficult In this paper, we propose a new image modeling method based on tetrahedrization to improve the visualization of three-dimensional medical volumetric data. In this method, the trivariate piecewise linear interpolation is applied through the constructed tetrahedral domain. Also, visualization methods including iso-surface, color contouring, and slicing are discussed. This method can be useful to the correct and speedy analysis of medical volumetric data, because it doesn't have the ambiguity problem of Marching Cubes algorithm and achieves the data reduction. We expect to compensate the degradation of an accuracy by using an adaptive sub-division of tetrahedrization based on least squares fitting.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1784-1792
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• 2001

Numerical analysis on a parallel flow heat exchanger(PFHE) is performed using 2 dimensional turbulent porous modeling. This modeling can consider three-dimensional configuration of passage (flat tube with micro-channels), and the stability and accuracy of numerical results are improved. The geometrical parameters(e.g., the position of separators, inlet/outlet, and porosity of passages of a PFHE) are varied in order to examine the flow and thermal characteristics and flow distribution of the single phase multiple passages system. The flow non-uniformities along the paths of the PFHE are observed to evaluate the thermal performance of the heat exchanger. The location of inlet affects the heat transfer, and the location of outlet affects the pressure drop. The porosity with the optimum thermal performance is around 0.53.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.617-623
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• 2004

This paper describes a dynamic thermal model for a representative dual axis rotational Chemical-Mechanical Polishing (CMP) tool. The model is one-dimensional but configured in the two-dimensional space and consists of three sub-models (pad, wafer and slurry fluid), with the first and the second that are time-dependent heat conduction-convection models with linear stationary (wafer) and nonlinear moving (pad) boundary conditions, and the last one that is a heat transport-convection model (slurry fluid). The modeling approach is validated by comparing the simulation results with available experimental data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.869-874
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• 2014

It is possible to fabricate a three-dimensional (3D) shape using the solid freeform fabrication (SFF) technology. However, there are several problems in applying conventional SFF technologies to the direct manufacturing of a product. Hence, multimaterial SFF is gaining attention. Moreover, a 3D circuit device that is different from a conventional two-dimensional PCB can also be fabricated using multimaterial SFF. In this study, a hybrid system using fused deposition modeling and direct writing was designed for 3D circuit device fabrication.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.89-95
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• 2006

This study has numerically modelled the combustion processes of the turbulent swirling premixed lifted flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially-injected air jets induce the turbulent swirling flow which plays the crucial role to stabilize the turbulent lifted flame. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flamelet model. Two-dimensional and three-dimensional computations are made for the various swirl numbers and nozzle length. In terms of the centerline velocity profiles and flame liftoff heights, numerical results are compared with experimental data The three-dimensional approach yields the much better conformity with agreements with measurements without any analytic assumptions on the inlet swirl profiles, compared to the two-dimensional approach. Numerical clearly results indicate that the present level-set based flamelet approach has realistically simulated the structure and stabilization mechanism of the turbulent swirling stoichiometric and lean-premixed lifted flames in the low-swirl burner.

• Korean Journal of Computational Design and Engineering
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• v.12 no.1
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• pp.39-49
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• 2007

Recently three-dimensional (3-D) die design and production process has been widely introduced into the tooling shops of automotive manufacturers to reduce time-to-production of brand-new automobiles. 3-D solid models created in CAD systems are used not only for various simulations for design verification, but also for NC tool path generation to machine dies and their Styrofoam patterns. However, a lot of time and cost will be required to build solid models for dies if designers use only the generalized modeling capabilities of commercial 3-D CAD systems. To solve this problem, it is necessary to customize 3-D CAD system for the specific die design and manufacturing process. This paper describes a dedicated 3-D CAD system based on Unigraphics for die design for automotive body panels. The system provides not only 3-D design capabilities, but also standard part libraries, to enhance design productivity. The design process modeling technology has been introduced to facilitate redesign of the die for the modified panel. By introducing this system, dies can be designed more rapidly in the 3-D space, and their solid data can be directly transferred to CAM tools for NC tool path generation and simulation tools for virtual manufacturing.