• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.12
• /
• pp.1045-1059
• /
• 2011

A 3-D multi-function radar(MFR) is a modern radar to provide various target information, such as range, doppler, and angle by performing surveillance, multiple target tracking, and missile guidance. In this paper, we introduced a real-time radar signal processor(RSP), which is a crucial component of MFR with its design, implementation using high-speed multiple DSP, and performance. Additionally, we verified that several advanced signal processing algorithms were well-performed in our RSP, such as MCA-CFAR algorithm for target detection in clutter environment, range and velocity measurement algorithm using discriminator estimation, and noise jammer detection algorithm using local minimum selection.

• KIEAE Journal
• /
• v.16 no.1
• /
• pp.81-87
• /
• 2016

Purpose: Heat transfers phenomena are described by the second order partial differential equation and its boundary conditions. In a three-dimensional structure of a building, the heat transfer phenomena generally include more than one material, and thus, become complicate. The analytic solutions are useful to understand heat transfer phenomena, but they can hardly be applied in engineering or design problems. Engineers and designers have generally been forced to use numerical methods providing reliable results. Finite volume methods with the unstructured grid system is only the suitable means of the analysis for the complex and arbitrary domains. Method: To obtain an numerical solution, a discretization method, which approximates the differential equations, and the interpolation methods for temperature and heat flux between two or more materials are required. The discretization methods are applied to small domains in space and time, and these numerical solutions form the descretized equations provide approximated solutions in both space and time. The accuracy of numerical solutions is dependent on the quality of discretizations and size of cells used. The higher accuracy, the higher numerical resources are required. The balance between the accuracy and difficulty of the numerical methods is critical for the success of the numerical analysis. A simple and easy interpolation methods among multiple materials are developed. The linear equations are solved with the BiCGSTAB being a effective matrix solver. Result: This study provides an overview of discretization methods, boundary interface, and matrix solver for the 3-dimensional numerical heat transfer including two materials.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.8
• /
• pp.1765-1772
• /
• 2012

Success rate of transplantation of body organs improved due to development of medical equipment and diagnostic technology. In particular, a liver transplant due to liver dysfunction has increased. With the development of image processing and analysis to obtain the volume for liver transplantation have increased the accuracy and efficiency. In this thesis, we try to reconstruct the regions of the liver within three dimensional images using the mevislab tool, which is effective in quick comparison and analysis of various algorithms, and in expedient development of prototypes. Liver is divided by applying threshold values and region growing method to the original image, and by removing noise and unnecessary entities through morphology and region filling, and setting of areas of interest. It is deemed that high temporal efficiency, and presentation of diverse range of comparison and analysis module application methods through usage of MeVisLab would make contribution towards expanding of baseline of medical image processing researches.

• Korean Chemical Engineering Research
• /
• v.54 no.4
• /
• pp.479-486
• /
• 2016

The efficient steam drum should be required to reduce carbon oxide emissions and heat recovery in oxygen converter hood system. However, steam generation is limited to the time of the oxygen blowing period, which is intermittent or cyclical in operation of steel-making process. Thus, steam drum should be optimized for an effective steam generation during the oxygen blowing portion of the converter cycle. In this study, a three-dimensional computational fluid dynamics (CFD) model has been developed to describe the impacts of changing various operating conditions and geometric shape on thermo-fluid characteristics and performance of the steam drum. This model encompasses not only fluid flow and heat transfer but also evaporation and condensation at the interfacial surface in the steam drum by using VOF (Volume of Fluid) method. To validate the prediction performance of this model, comparison of the steam flow rate between numerical and experimental result has been performed, resulting in the accuracy of the relative error by less than 3.2%.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.2
• /
• pp.156-162
• /
• 2008

The static aeroelastic analysis of composite hingeless rotor blades in hover was performed using free-wake method. Large deflection beam theory was applied to analyze blade motions as a one-dimension beam. Anisotropic beam theory was applied to perform a cross-sectional analysis for composite rotor blades. Aerodynamic loads were calculated through a three-dimensional aerodynamic model which is based on the unsteady vortex lattice method. The wake geometry in hover was described using a time-marching free-wake method. Numerical results of the steady-state deflections for the composite hingeless rotor blades were presented and compared with those results based on two-dimensional quasi-steady strip theory and prescribed wake method. It was shown that wakes affect the steady-state deflections.

• Composites Research
• /
• v.17 no.3
• /
• pp.29-37
• /
• 2004

The aeroelastic stability analysis of composite bearingless rotors is investigated using a large deflection beam theory in hover. The bearingless rotor configuration consists of a single flexbeam with a wrap-around type torque tube and the pitch links located at the leading edge and trailing edge of the torque tube. The outboard main blade, flexbeam and torque tube are all assumed to be an elastic beam undergoing flap bending, lead-lag bending, elastic twist and axial deflections, which are discretized into beam finite elements. For the analysis of composite bearingless rotors, flexbeam is assumed to be a rectangular section made of laminate. Two-dimensional quasi-steady strip theory is used for aerodynamic computation. The finite element equations of motion for beams are obtained from Hamilton's principle. The p-k method is used to determine aeroelastic stability boundary. Numerical results are presented for selected bearingless rotor configurations based on the lay-up of laminae in the flexbeam and pitch links location. A systematic study is made to identify the importance of the stiffness coupling terms on aeroelastic stability for various fiber orientation and for different configuration.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.6
• /
• pp.2160-2170
• /
• 1991

Three-dimensional turbulent structures in the near field of elliptic jet were experimentally investigated by using a three-color, three-component Laser Doppler Velocimeter. The Reynolds number based on the nozzle exit velocity and nozzle equivalent diameter(De) was about 4*10$^{4}$. The turbulent characteristics of a sharp-edged elliptic nozzle with aspect ratio of 2 were analyzed along major and minor axis at X/De=2,3,5,7 and along the centerline up to X/De=14. Quantities measured at each point with the 3-D LDV system were three orthogonal velocity components, turbulent intensity, skewness, flatness, and Reynolds shear stress. The nondimensional mean velocities coincided well with the Schlichting's empirical curve with going downstream. Elliptic jet of AR=2 had two switching points at about X/De=2 and 16. The turbulent intensity along the minor axis was distributed widely than that along the major axis. In the near field, X/De<5, the Reynolds shear stresses of the inner part of the elliptic jet had negative value, which indicated the enhancement of entrainment toward the inner part.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2005.05a
• /
• pp.848-853
• /
• 2005

3D geometric modeling of an object of interest has been intensively investigated in many fields including CAD/CAM and computer graphics. Traditionally, CAD and geometric modeling tools are widely used to create geometric models that have nearly the same shape of 3D real objects or satisfy designers intent. Recently, with the help of the reverse engineering (RE) technology, we can easily acquire 3D point data from the objects and create 3D geometric models that perfectly fit the scanned data more easily and fast. In this paper, we present 3D geometric model generation based on a stereo vision system (SVS) using random pattern projection. A triangular mesh is considered as the resulting geometric model. In order to obtain reasonable results with the SVS-based geometric model generation, we deal with many steps including camera calibration, stereo matching, scanning from multiple views, noise handling, registration, and triangular mesh generation. To acquire reliable stere matching, we project random patterns onto the object. With experiments using various random patterns, we propose several tips helpful for the quality of the results. Some examples are given to show their usefulness.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.11
• /
• pp.1080-1087
• /
• 2009

This paper presents an algorithm to acquire 3D geometric information using a virtual plane method. The method to measure 3D information on the plane is easy, because it's not concerning value on the z-axis. A plane can be made by arbitrary three points in the 3D space, so the algorithm is able to make a number of virtual planes from feature points on the target object. In this case, these geometric relations between the origin of each virtual plane and the origin of the target object coordinates should be expressed as known homogeneous matrices. To include this idea, the algorithm could induce simple matrix formula which is only concerning unknown geometric relation between the origin of target object and the origin of camera coordinates. Therefore, it's more fast and simple than other methods. For achieving the proposed method, a regular pin-hole camera model and a perspective projection matrix which is defined by a geometric relation between each coordinate system is used. In the final part of this paper, we demonstrate the techniques for a variety of applications, including measurements in industrial parts and known patches images.

• Journal of Environmental Science International
• /
• v.21 no.4
• /
• pp.471-478
• /
• 2012

In this study, the flow characteristic analysis at the curved-channel of the actual channel section is compared and reviewed using the 2D RMA-2 model and the 3D FLOW-3D model. the curve section with curve rate 1.044 in the research section is analyzed applying the frequency of he project flood of 100 years. According to the result, the issue for the application of the FLOW-3D Model's three-dimensional numeric analysis result to the actual river is found to be reviewed with caution. Also, application of the 3D model to the wide basin's flood characteristic is determined to be somewhat risky. But, the applicability to the hydraulic property analysis of a partial channel section and the impact analysis and forecast of hydraulic structure is presumed to be high. In addition, if the parameters to reflect the vegetation of basin and the actual channel, more accurate topological measurement data and the topological data with high closeness to the current status are provided, the result with higher reliability is considered to be drawn.