• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.381-391
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• 2005

The design methodology of injection molding die has been changed from two-dimensional drafting to three-dimensional solid modeling, which is due to many advantages over the conventional methodology in terms of design modification and data associativity. In addition to the solid modeling capability, it is required for a mold designer to utilize a database management system that facilitates efficient mold design. In the paper presented is the implementation of a software program which automatically generates three-dimensional mold-bases including standard parts and slider parts, conforming to given geometric constraints. It is based on a commercial CAD system (Unigraphics NX) along with related API (application program interface) libraries. The research is expected to reduce design efforts and simplify construction of a complex three-dimensional mold-base model that is comprised of standard parts and slider parts, by use of the three-dimensional database and automatized geometric dimensioning.

• Journal of ILASS-Korea
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• v.13 no.3
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• pp.117-125
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• 2008

The correlations for the prediction of maximum liquid-phase penetration in diesel spray are reviewed in this study. The existing models developed for the prediction of maximum liquid-phase penetration can be categorized as the zero-dimensional (empirical) model, the multi-dimensional model and the other model. The existing zero-dimensional model can be classified into four groups and the existing multidimensional models can be classified into three groups. The other model includes holistic hydraulic and spray model. The maximum liquid-phase penetration is mainly affected by nozzle diameter, fuel volatility, injection pressure, ambient gas pressure, ambient gas density and fuel temperature. In the case of empirical correlations incorporated with spray angle, the predicted results will be different according to the selection of correlation for spray angle. The research for the effect of boiling point temperatures on maximum liquid-phase penetration is required. In the case of multidimensional model, there exist problems of the grid and spray sub-models dependency effects.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.53-61
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• 2019

This study performs reliability analysis of three-dimensional temporary shoring structures with three different models. The first model represents a field model which does not have diagonal bracing members. The installation of bracing members is often neglected in the field for convenience. The second model corresponds to a design model which has the bracing members with the hinge connection of horizontal and bracing members at joints. The third model is similar to the second model but the hinge connection is replaced with partial rotational stiffness. The reliability analysis results revealed that the vertical members of the three models are safe enough in terms of axial force, but the vertical and horizontal members exhibit a big difference among the three models in terms of combination stress of axial force and bi-axial bending moments. The field model showed significant increase in failure probability for the horizontal member, and thus the results demonstrate that the bracing member should be installed necessarily for the safety of the temporary shoring structures.

• Journal of the Korean Data and Information Science Society
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• v.17 no.2
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• pp.543-557
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• 2006

This paper is concerned with the applicability of the chi-square approximation to the six disparity statistics: the Pearson chi-square, the generalized likelihood ratio, the power divergence, the blended weight chi-square, the blended weight Hellinger distance, and the negative exponential disparity statistic. Three dimensional contingency tables of small and moderate sample sizes are generated to be fitted to all possible hierarchical log-linear models: the completely independent model, the conditionally independent model, the partial association models, and the model with one variable independent of the other two. For models with direct solutions of expected cell counts, point estimates and confidence intervals of the 90 and 95 percentage points of six statistics are explored. For model without direct solutions, the empirical significant levels and the empirical powers of six statistics to test the significance of the three factor interaction are computed and compared.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.550-559
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• 2014

Hydraulic performance of the 1 inch ball valve have been analyzed based on the three-dimensional Reynolds-averaged Navier-Stokes analysis and an experiment. The experimental test rig of the 1 inch ball valve has been developed to investigate pressure drop for the 1 inch ball valve. The numerical model, which has reliability and effectiveness, has been constructed through the grid dependency test and validation with the results of the experiment. Shear stress transport turbulence model has been used to enhance an accuracy of the turbulence prediction in the pipeline and ball valve, respectively. Effects of the ball valve angle on the flow characteristics and friction performance have been evaluated.

• Computers and Concrete
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• v.1 no.3
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• pp.261-284
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• 2004

Two enhancements to a recently developed plastic-damage-contact model for concrete are presented. The model itself, which uses planes of degradation that can undergo damage and separation but that can regain contact according to a contact law, is described. The first enhancement is a new damage evolution function which provides a completely smooth transition from the undamaged to the damaged state and from pre-peak to post-peak regions. The second is an improved contact function that governs the potential degree of contact with increasing opening on a crack plane. The use of a damage evolution function with a pre-peak has implications for the consistent tangent matrix/stress recovery algorithm developed for the model implementation, and amendments to this algorithm to accommodate the new function are described. A series of unpublished experimental tests on notched specimens undertaken in Cardiff in the mid 1990s are then described. These include notched beam tests as well as prismatic and cylindrical torsion tests. The tests are then considered in three dimensional finite element analyses using the modified Craft model implemented in the finite element program LUSAS. Comparisons between experimental and numerical data show reasonable agreement except that the numerical simulations do not fully describe the latter stages of the softening responses for the torsion examples. Finally, it is concluded that the torsion tests described provide useful benchmark examples for the validation of three-dimensional numerical models for concrete.

• Spatial Information Research
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• v.21 no.3
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• pp.55-69
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• 2013

In the modern society, as the city grows and constructive technology gradually develops, land usage has been sophisticated and three-dimensionalized. Consequently, issues such as property ownership and legal claim over ground and underground space have been triggered, which disclose the problems of using two-dimensional cadastral management system. Numerous researches on building three-dimensional cadastral are ongoing such as defining the right relationship of land space and providing the registration and management scheme so as to solve the imminent matter. It is the chief aim of this study to increase efficiency by analyzing the vocational practices through adding on necessary sections and properties for current registration to original research work. If three-dimensional cadastral management system is once constructed, highly qualified services for citizens will be available by providing accurate land related information swiftly, which can result in inevitable improvement of efficiency at work. Hence, this thesis will suggest the internationally suitable feature model development method in terms of standardization by probing into the factual profession to derive each attributes and properties that are related to three-dimensional cadastral and affix them to the classified item requisites of initial research studies.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.155-158
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• 2006

In the present paper, the scale effects of two-dimensional airfoil and three-dimensional wind turbine were investigated by using FLUENT software. For two dimensional analysis, flow around S809 airfoil with various Reynolds No. and Mach No. conditions were simulated. For three dimensional analysis, scaled NREL Phase VI wind turbine models from 6% to 1,600% were simulated under the same tip speed ratio condition. Finally, aerodynamic comparisons between two-dimensional flow and three dimensional wind turbine flow are made for the feasibility study of scale effect corrections. Currently, KARI(Korea Aerospace Research Institute) is preparing for the wind tunnel test of 12% NREL Phase VI wind turbine and the performance analysis of the scaled NREL wind turbine model will be validated by the wind tunnel test.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.345-371
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• 1994

Restorative procedures can lead to weakening tooth due to reduction and alteraton of tooth structure. It is essential to prevent fractures to conserve tooth. Among the several parameters in cavity designs, cavity isthmus and depth are very important. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional. finite element models were made by serial photographic method and cavity depth(1.7mm, 2.4mm) and isthmus (11 4, 1/3, 1/2 of intercuspal distance) were varied. linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B, G and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall. Both compressive and tensile forces were distributed directly to the adjacent regions. G model(Gap Distance: 0.000001mm) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). When compression occurred along the interface, the forces were transferred to the adjacent regions. However, tensile forces perpendicular to the interface were excluded. R model was assumed non-connection between the restoration and cavity wall. No force was transferred to the adjacent regions. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, von Mises stress, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as follows: 1. G model showed stress and strain patterns between Band R model. 2. B model and G model showed the bending phenomenon in the displacement. 3. R model showed the greatest amount of the displacement of the buccal cusp followed by G and B model in descending order. G model showed the greatest amount of the displacement of the lingual cusp followed by B and R model in descending order. 4. B model showed no change of the displacement as increasing depth and width of the cavity. G and R model showed greater displacement of the buccal cusp as increasing depth and width of the cavity, but no change in the displacement of the lingual cusp. 5. As increasing of the width of the cavity, stress and strain were not changed in B model. Stress and strain were increased on the distal marginal ridge and buccopulpal line angle in G and R model. The possibility of the tooth fracture was increased. 6. As increasing of the depth of the cavity, stress and strain were not changed in B and G model. Stress and strain were increased on the distal marginal ridge and buccopulpal line angle in R model. The possibility of the tooth fracture was increased.

• Journal of Korean Port Research
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• v.13 no.2
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• pp.427-436
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• 1999

Simulation model for diffusion of oil spill is developed. The model can perform real time simulation in the case of oil spill accident in the ocean. The model consists of three dimensional ocean circulation model and model for diffusion of oil spill. Real time flow fields which are used in the calculation of advection of oil spill are obtained in the three dimensional ocean circulation model. The model for diffusion of oil spill includes the evaporation dissolution emulsification and downward diffusion. For the verification of the model it is applied to the oil spill from the accident of Sea Prince. The results shows good agreement.