• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.3
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• pp.7-15
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• 2006

Aerodynamic analysis of an airfoil in the transonic region was automated in order to enable parametric study by using the journal file of the commercial analysis code FLUENT, pre/post process Gambit and computational mathematics code MATLAB. The automated capability was illustrated via NACA 0012 and RAE 2822 airfoils. This analysis was carried out at Mach numbers ranged from 0.70 to 0.80, angles of attack; 1$^{\circ}$, 2$^{\circ}$ and 4$^{\circ}$, Reynolds numbers; 4.0${\times}$106, 6.5${\times}$106. The analysis results of a pressure coefficient were verified by comparing with the experimental data which were measured in terms of chord length because the pressure coefficient of an airfoil surface is a good estimator of flow characteristics. The results of two airfoils show that this analysis code is useful enough to be used in the design optimization of airfoil.

• Fire Science and Engineering
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• v.18 no.2
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• pp.73-78
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• 2004

This study investigated about smoke/heat interception screen that can protect underneath of fire door and floor when occur fire, and keep out leakage or diffusion of smoke/heat. In this study, to considered differential pressure form smoke control area and mechanical force by fluid buoyancy of smoke when occur fire and stream of heat, are analyzed to used $ANSYS^{\circledR}$ of finite element analysis code. It presented direction of optimal design of smoke/heat interception screens that can minimize loading condition from study results, and helped that construct basic engineering data of smoke/heat interception systems as that utilize its shape design of smoke/heat interception screens.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2202-2209
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• 2009

Joint paths are induced mathematically for many kinds of joint pattern between master- and sub-pipes. By compensating them with root gap of welds and kerf width, real cutting paths are determined. Their NC codes are generated, and the paths generated by NC code are verified by a ghost function. A beveling is implemented through tilting a torch in the A- and B-axis direction for 8 sections in the chuck rotation of C-axis. The effective CAM program was developed specially for 6-axis CNC pipe coasters which cut a master or sub- pipe along the cutting path and simultaneously fulfill a beveling process.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.26-34
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• 2009

Secondary flow losses can be as high as 30~50% of the total aerodynamic losses for a turbo-machinery blade or stator row. These are important part for improving a turbine efficiency. Therefore, many studies have been performed to decrease the secondary flow losses. The present study deals with the chamfered leading-edge at a generic wing-body junction to decrease the horseshoe vortex, one of factors to generate the secondary flow losses, and investigates the vortex generation and the characteristics of the horseshoe vortex with the chamfered height, and depth of the chamfer by using $FLUENT^{TM}$. It was found that the total pressure loss for the best case can be decreased about 1.55% compare to the baseline case.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.4
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• pp.335-344
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• 2014

The Quality of municipal solid waste incineration ash (incineration ash) was analyzed for the purpose of the reusing for concrete material. The folwability and strength properties of concrete mixed with incinerator ash were investigated. CaO component was included more than 50% in chemical component of incinerator ash, mean size of 50% accumulated particle distribution of incinerator ash was about $25{\mu}m$. Particle shape of incinerator ash ($IA_1$) was massed the round shape with fine particle, particle shape of incinerator ash ($IA_2$) was piled up the sheet shape according to manufacture procedure. The Quality of concrete was effected by use of incinerator ash. When the incinerator Ash ($IA_2$) was used, slum of concrete was increased and dosage of high range water reducing agent was reduced. However, strength development of concrete was decreased. Dosage of high range water reducing agent was increased by combined use of incinerator ash ($IA_2$) and diatomite powder, but strength development of concrete was improved. Ratio of compressive strength and tensile strength was in the range 85%~105% of CEB-FIP model code.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.672-679
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• 2018

This paper describes a methodology for shape design using an optimal design system, whereas generally a three dimensional analysis is required for such designs. An automatic finite element mesh generation technique, which is based on fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with a commercial FE analysis code and a commercial solid modeler. Also, with the aid of multilayer neural networks, the present system allows us to automatically obtain a design window, in which a number of satisfactory design solutions exist in a multi-dimensional design parameter space. The developed optimal design system is successfully applied to evaluate the structures that are used. This study used a stress gauge to measure the maximum stress affecting the parts of the side housing bracket which are most vulnerable to cracking. Thereafter, we used a tool to interpret the maximum stress value, while maintaining the same stress as that exerted on the spot. Furthermore, a stress analysis was performed with the typical shape maintained intact, SM490 used for the material and the minimizing weight safety coefficient set to 3, while keeping the maximum stress the same as or smaller than the allowable stress. In this paper, a side housing bracket with a comparably simple structure for 36 tons was optimized, however if the method developed in this study were applied to side housing brackets of different classes (tons), their quality would be greatly improved.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.329-335
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• 2011

The finite element method (FEM) has been used for various fields like mathematics and engineering. However, the FEM has a difficulty in describing the geometric shape exactly due to its property of piecewise linear discretization. Recently, however, a so-called isogeometric analysis method that uses the non-uniform rational B-spline(NURBS) basis function has been developed. The NURBS can be used to describe the geometry exactly and play a role of basis functions for the response analysis. Nevertheless, constructing the NURBS basis functions in analysis is as costly as a meshing process in the FEM. Since the isogeometric method shares geometric data with CAD, it is possible to intactly import the model data from commercial CAD tools. In this paper, we use the Rhinoceros 3D software to create CAD models and export in the form of STEP file. The information of knot vectors and control points in the NURBS is utilized in the isogeometric analysis. Through some numerical examples, the accuracy of isogeometric method is compared with that of FEM. Also, the efficiency of the isogeometric method that includes the CAD and CAE in a unified framework is verified.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.200-214
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• 1993

This paper presents the results of fluidelastic instability analysis performed for the U-tube bundle of a Westinghouse model 51 steam generator, one of the recirculating types designed at an early stage, in which the principal region of external cross-flow is associated with the U-bend portion of tube. The prerequisites for this analysis are detailed informations of the secondary side flow conditions in the steam generator and the free vibration behaviours of the U-tubes. In this study, the three-dimensional two-phase flow field in the steam generator has been calculated employing the ATHOS3 steam generator two-phase flow code and the ANSYS engineering analysis code has been used to calculate the free vibration responses of specific U tubes under consideration. The assessment of the potential instability for the suspect U-tubes, which is the final analysis process of the present work, has been accomplished by combining the secondary side velocity and density distributions obtained from the ATHOS3 prediction with the relative modal displacement and natural frequency data calculated using the ANSYS code. The damping of tubes in two-phase flow has been deduced from the existing experimental data by taking into account the secondary side void fraction effect. In operation of the steam generator, the tube support conditions at the tube-to-tube support plate intersections due to either tube denting degradation or deposition of tube support plate corrosion products or ingression of dregs. Thus, various hypothetical cases regarding the tube support conditions at the tube-to-tube support plate intersections have been considered to investigate the clamped support effects on the forced vibration response of the tube. Also, the effect of anti-vibration bars support in the curved portion of tube has been examined.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.11-23
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• 1997

This paper contains a new approach to blade section design method for marine propellers. The hydrodynamic characteristics of 2-D section are highly influenced by its geometrical parameters i.e., thickness and camber distributions and leading edge radius etc. To consider fully turbulent flow field near 2-D section. the finite volume method with k-${\varepsilon}$ turbulent model which solve Reynolds time averaged Navier-Stokes(RANS) equation is applied. In this study, O-type grid system that can provide many calculation points on blade surface is used. The results were compared with those of the experiment of NACA0012 to confirm the accuracy of the developed codes. The goal of this study is the development of a blade section with high efficiency and low drag. To achieve this, we carried out the tests of lift, drag and cavitation characteristics in cavitation tunnel. The results of experiment were compared with numerical results in order to validate the proposed blades design method. By comparing the numerical results with the experiments, we found that the new blade section, KH28 allows superior performance in efficiency and cavitation avoidance characteristics. We further investigated the blade section design method and an application study of this section, KH28 to apply to the marine propeller. In order to improve the accuracy of numerical results on prediction of lift and drag, we conclude here that the 2-layer boundary model must be used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.319-330
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• 2016

Recently, 3D printing technology has been applied to make a concept model and working mockup of an industrial application. On the other hand, this technology has limited applications in industrial products due to the materials and reliability of the 3D printed product. In this study, the components of a full cord switch module are proposed as a case of a 3D printed component that can be used as a substitute for a short period. These are hub-driven and lever lockup components that have the structural characteristics of breaking down frequently in the emergency operating status. To ensure the structural strength for a substitute period, research of structure optimization was performed because 3D printing technology has a limitation in the materials used. After optimizing the structure variables of the hub-driven component, reasonable results can be drawn in that the safety factors of the left and right switching mode are 1.243 (${\Delta}153.67%$) and 3.156 (${\Delta}404.96%$). The lever lockup component has a structural weak point that can break down easily on the lockup-part because of a cantilever shape and bending moment. The rib structure was applied to decrease the deflection. In addition, optimization of the structural variables was performed, showing a safety factor of 7.52(${\Delta}26%$).