• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1436-1443
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• 2019

A fast gamma-ray dose rate assessment method for complex geometries based on stylized model reconstruction and point-kernel method is proposed in this paper. The complex three-dimensional (3D) geometries are imported as a 3DS format file from 3dsMax software with material and radiometric attributes. Based on 3D stylized model reconstruction of solid mesh, the 3D-geometrical solids are automatically converted into stylized models. In point-kernel calculation, the stylized source models are divided into point kernels and the mean free paths (mfp) are calculated by the intersections between shield stylized models and tracing ray. Compared with MCNP, the proposed method can implement complex 3D geometries visually, and the dose rate calculation is accurate and fast.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.200-205
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• 2022

This paper presents an improved maximum power point tracking method that can fast track the global maximum power point (GMPP) for a photovoltaic system under partial shading conditions. The proposed method combines the advantages of the maximum power trapezium (MPT) method and the search-skip-judge method to minimize the tracking voltage intervals. Thus, the proposed method can quickly track the GMPP by skipping unnecessary tracking voltage intervals. The superiority of the proposed method is verified through simulation results in the MATLAB/Simulink and experimental real-time operation results with the hardware-in-the-loop simulation. The simulation and experimental results demonstrated that the proposed method has a faster tracking time than the MPT method under various partial shading conditions.

• Journal of Information Processing Systems
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• v.13 no.3
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• pp.491-499
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• 2017

In this study, we proposed a new approach to segment ground and nonground points gained from a 3D laser range sensor. The primary aim of this research was to provide a fast and effective method for ground segmentation. In each frame, we divide the point cloud into small groups. All threshold points and start-ground points in each group are then analyzed. To determine threshold points we depend on three features: gradient, lost threshold points, and abnormalities in the distance between the sensor and a particular threshold point. After a threshold point is determined, a start-ground point is then identified by considering the height difference between two consecutive points. All points from a start-ground point to the next threshold point are ground points. Other points are nonground. This process is then repeated until all points are labelled.

• Journal of Broadcast Engineering
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• v.26 no.3
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• pp.258-268
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• 2021

Point cloud content is immersive content that represents real-world objects with three-dimensional (3D) points. In the process of acquiring point cloud data or encoding and decoding point cloud data, the resolution of point cloud content could be degraded. In this paper, we propose a method of progressively enhancing the resolution of sequential point cloud contents through inter-frame registration. To register a point cloud, the iterative closest point (ICP) algorithm is commonly used. Existing ICP algorithms can transform rigid bodies, but there is a disadvantage that transformation is not possible for non-rigid bodies having motion vectors in different directions locally, such as point cloud content. We overcome the limitations of the existing ICP-based method by registering regions with motion vectors in different directions locally between the point cloud content of the current frame and the previous frame. In this manner, the resolution of the point cloud content with geometric movement is enhanced through the process of registering points between frames. We provide four different point cloud content that has been enhanced with our method in the experiment.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.263-274
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• 2018

In this study, we propose a frequency domain spectral element method (SEM) for the vibration analysis of a multi-span beam subjected to a moving point force. This study is an extension of the authors' previous study for a single-span beam subjected to a moving point force, where the two-element model-based SEM was applied. In this study, each span of a multi-span beam is represented by the Timoshenko beam model and the moving point force is transformed into the frequency domain as a series of each stationary point force distributed on the multi-span beam. The span at which a stationary point force is located is represented by two-element model, but all other spans are represented by one-element models. The vibration responses to a moving point force are obtained by superposing all individual vibration responses generated by each stationary point force. The high accuracy and computational efficiency of the proposed SEM are verified by comparing the solutions by SEM with exact analytical solutions by the integral transform method (ITM) as well as the solutions by the finite element method (FEM).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.435-438
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• 2001

Reverse engineering technology refers to the process that creates a CAD model of an existing part using measuring devices. Recently, non-contact scanning devices have become more accurate and the speed of data acquisition has increased drastically. However, they generate thousands of points per second and various types of point data. Therefore, it becomes a major issue to handle the huge amount and various types of point data. To generate a CAD model from scanned point data efficiently, these point data should be well arranged through point data handling processes such as data reduction and segmentation. This paper proposes a new point data handling method using 3D grids. The geometric information of a part is extracted from point cloud data by estimating normal values of the points. The non-uniform 3D grids for data reduction and segmentation are generated based on the geometric information. Through these data reduction and segmentation processes, it is possible to create CAD models autmatically and efficiently. The proposed method is applied to two quardric medels and the results are discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.3108-3120
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• 2019

Point cloud is widely used in 3D applications due to the recent advancement of 3D data acquisition technology. Polygonal mesh-based compression has been dominant since it can replace many points sharing a surface with a set of vertices with mesh structure. Recent point cloud-based applications demand more point-based interactivity, which makes point cloud compression (PCC) becomes more attractive than 3D mesh compression. Interestingly, an exploration activity has been started to explore the feasibility of PCC standard in MPEG. In this paper, a new color attribute compression method is presented for point cloud data. The proposed method utilizes the spatial redundancy among color attribute data to construct a color palette. The color palette is constructed by using K-means clustering method and each color data in point cloud is represented by the index of its similar color in palette. To further improve the compression efficiency, the spatial redundancy between the indices of neighboring colors is also removed by marking them using a flag bit. Experimental results show that the proposed method achieves a better improvement of RD performance compared with that of the MPEG PCC reference software.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.267-272
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• 2023

This study was conducted to investigate the effect of integrated pest management (IPM) with 3point 5score microscopic monitoring method for laying farms infected with poultry red mites. A total of 8 laying farms infected with poultry red mites were divided into two treatments: 1) integrated pest management with 3point 5score microscopic monitoring method and 2) normal pest management with 3point 5score microscopic monitoring method. The results revealed that there is no significant difference between the groups with respect to the score of poultry red mites not only regardless of disinfection for the laying farms but also from week 4 to week 20 (P>0.05). However, the farm with IPM had a lower (P<0.05) score than those with the normal pest management method on week 24. Based on the result of the present study, controlling the presence of poultry red mites using IPM, along with consistent monitoring and supplementation using the 3point 5score microscopic monitoring method, is deemed effective in reducing the ultimately targeted infection rate of poultry red mites.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.130-133
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• 2005

Efficient finite element method has been introduced for metallic sandwich plates subject to 3-point bending. A full model 3-point bending FE-analysis shows that plastic behavior of inner structures appears only at the load point. So, Unit structures of sandwich plates are defined to numerically calculate the bending stiffness with recurrent boundary condition of pure bending. And then equivalent models with same bending stiffness and strength of full models are designed analytically. It is demonstrated that results of both models are almost same and FE analysis method with equivalent models can reduce analysis time effectively.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.3
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• pp.171-177
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• 2013

This paper presents a fuzzy set method to enforce complementarity constraints (CCs) in a nonlinear interior point method (NIPM)-based optimization. NIPM is a Newton-type approach to nonlinear programming problems, but it adopts log-barrier functions to deal with the obstacle of managing inequality constraints. The fuzzy-enforcement method has been implemented for CCs, which can be incorporated in optimization problems for real-world applications. In this paper, numerical simulations that apply this method to power system optimal power flow problems are included.