• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1641-1646
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• 2011

The second-generation magnetic abrasive polishing is one of the nontraditional machining technologies newly developed. Because of the flexibility effect in magnetic abrasive polishing, the precise and mirror like surface can be obtained during this process. In this study, magnetic abrasive polishing process was applied in small grooved surface. As a result, it was seen that the flexible magnetic abrasive tool was effective to remove burrs on the edge of the groove. However, the efficiency of magnetic abrasive polishing at the slot was very low according to increasing depth and width of slot. So, correlation between geometric parameters, such as the depth and width, and surface roughness was evaluated and the minimum width for suitable polishing was found by experimental results.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.955-960
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• 2019

The Computed tomography (CT) scan can have high radiation in a few tests, and this risk is significant given that it is often repeated in one patient. In children, the incidence of radiation-induced cancer is reported because organs are growing, are more sensitive to radiation. 3D printing has recently been studied to be applied to various applications as a research field for 3D printing applications, research on fabrication of radiation shields and materials has been conducted. The purpose of the 3D printer is to replace the existing panel-type shields and to make customized designs according to the shape of the human body. Therefore, research on 3D information processing to be input to the 3D printer is also necessary. In this study, 3D data of the human body surface, which is the preliminary step of the manufacture of patient-specific eye shield using stereo vision depth map technology, was studied. This study aims to increase the possibility of three-dimensional output. As a result of experimenting with this method, which is relatively simple compared with other methods of 3D information processing, the minimum coordinates for 3D information are extracted. The results of this study provided the advantages and limitations of stereo images using natural light and will be the basic data for the manufacture of eye shields in the future.

• Journal of the Korean Geophysical Society
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• v.9 no.4
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• pp.377-386
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• 2006

There is an inseparable relation between human race and engineering work. As world developed into highly industrialized society, a diversity of large structures is being built up correspondently to limited topographical circumstance. Though large structures are national establishments which provide us with convenience of life, there are some disastrous possibilities which were never predicted such as ground subsidence and degradation. It is very difficult to analyze the volume of total metamorphosis with the relative displacement measurement system which is now used and it is impossible to know whether there is structural metamorphosis within a permissible range of design or not. In this research with an object of 13-year-old earthen dam, through generating point-cloud which has 3D spatial coordinates(x, y, z) of this dam by means of 3D Laser Scanning, we can get real configuration data of slanting surface of this dam with this method of getting a number of 3D spatial coordinates(x, y, z). It gives 3D spatial model to us and we can get various information of this dam such as the distance of slanting surface of dam, dimensions and cubic volume. It can be made full use of as important source material of reinforcement and maintenance works to detect previously the bulging of the dam through this research.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.6
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• pp.307-317
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• 2002

In this paper we propose a new mesh reconstruction scheme that produces a displaced subdivision surface directly from unorganized points. The displaced subdivision surface is a new mesh representation that defines a detailed mesh with a displacement map over a smooth domain surface, but original displaced subdivision surface algorithm needs an explicit polygonal mesh since it is not a mesh reconstruction algorithm but a mesh conversion (remeshing) algorithm. The main idea of our approach is that we sample surface detail from unorganized points without any topological information. For this, we predict a virtual triangular face from unorganized points for each sampling ray from a parameteric domain surface. Direct displaced subdivision surface reconstruction from unorganized points has much importance since the output of this algorithm has several important properties: It has compact mesh representation since most vertices can be represented by only a scalar value. Underlying structure of it is piecewise regular so it ran be easily transformed into a multiresolution mesh. Smoothness after mesh deformation is automatically preserved. We avoid time-consuming global energy optimization by employing the input data dependant mesh smoothing, so we can get a good quality displaced subdivision surface quickly.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.04a
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• pp.14-14
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• 2001

WC-Co 계의 입성장 억제는 현재 초경합금 분야에서 공학적으로 가장 중요한 이슈들 중의 하나이다 VC를 비롯한 입방정 탄화물이나 $Cr_3C_2$ 등의 여러 가지 탄화 물이 혼합되어 입성장 억제에 이용되는데 입성장 억제의 효과는 대략적으로 용해되는 탄화물의 양에 의존하고 있는 것으로 추정된다. 보다 효율적으로 입성장 억제를 실현하려면 입성장 기구를 명확히 할 필요가 있다. 최 등[1]은 VC가 WC 입자 표면 에서의 edge energy를 증가시켜서 2차원 핵생성의 에너지 장벽을 올리게 하고 이에 따라 입성장이 억제된다는 모델을 제안하였다. 이러한 모텔을 입증하기 위해서는 이론적으로만 예측이 가능한 edge energy보다 좀 더 명확한 물리적인 변수가 제시되어야 할 것이다. 여기서는 또 다른 계인 NbC- TiC-Co 계에서 NbC와 TiC의 버에 따른 입성장 거동과 입자의 형상간의 관계로부터 업성장과 edge energy 그리 고 edge energy와 입자 형상간의 관계를 알아보고 이로부터 좀 더 구체적인 의미 에서의 입성장 모텔과 입성장 억제기구를 제시하고자 한다.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.70-73
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• 2006

Mesh generation for the region of interest is prerequisite for numerical analysis of governing partial differential equations describing phenomena with proper physic. Mesh generation is, however, usually considered as a major obstacle for a routine application of numerical approaches in Engineering applications. Therefore automatic mesh generation is highly pursued. In this paper automated quadrilateral surface mesh generation is proposed. According to the present method, Cartesian cells of proper resolution for a region bounding the whole region of interest are first generated and the interior cells are identified. Then projecting their surface meshes onto the boundary surfaces gives surface mesh consisting of quadrilateral cells. This method has been implemented as an application program, and example cases are given.

• Journal of Sensor Science and Technology
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• v.11 no.5
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• pp.263-272
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• 2002

In this paper, we investigate the potential for retrieval of morphometric data from three dimensional images of conducting bronchus obtained by X-ray Computerized Tomography (CT) and to explore the potential for the use of rapid prototype machine to produce physical hollow bronchus casts for mathematical modeling and experimental verification of particle deposition models. We segment the bronchus of lung by mathematical morphology method from obtained images by CT. The surface data representing volumetric bronchus data in three dimensions are converted to STL(streolithography) file and three dimensional solid model is created by using input STL file and rapid prototype machine. Two physical hollow cast models are created from the CT images of bronchial tree phantom and living human bronchus. We evaluate the usefulness of the rapid prototype model of bronchial tree by comparing diameters of the cross sectional area bronchus segments of the original CT images and the rapid prototyping-derived models imaged by X-ray CT.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.1-7
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• 2003

In this study, steady/unsteady aerodynamic characteristic for three dimensional symmetric wing was investigated numerically using Vortex Panel Method. This program utilized linearly varying vortices in x and y directions distributed on the wing surface and was applied to the incompressible potential. flow around a three dimensional wing Separation and deformation of the wake are not considered. The comparison between NACA Airfoil Data and the computed results showed excellent agreement. πus method was applied to unsteady wings undergoing both sudden pitch-up and constant rate pitching motion. In the unsteady flow analysis, a formation and a time-dependent locations of Starting Vortices are considered and the effect of Starting Vortices on aerodynamic characteristic of the wing was calculated. The present method can be extended to apply for more complicated cases such as pitching, flapping and rotating wing analysis.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.369-380
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• 2005

This study describes image-based approach for efficient and objective evaluation method of the rock slope stability. Three-dimensional rock slope model was reconstructed by processing stereo digital images. The model provided fundamental information for geospatial analysis of the rock slope. Methods to extract three-dimensional information about discontinuity on the rock slope and to estimate roughness of the rock surfaces were suggested. The results show that stereo digital images have potential to provide information for both quantitative and qualitative analysis of rock slope. In addition, visualization of the results increases efficiency and benefit in evaluating rock slope stability.

• Journal of dental hygiene science
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• v.2 no.2
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• pp.121-124
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• 2002

The fructan-producing enzyme, fructosyltransferase (FTF), was immobilized on the surface of 4 differents hydroxyapatites by simple incubation. Among the resins, the Type I (${20{\mu}m}$) hydroxyapatite gave the highest yield in terms of immobilization yield and enzyme activity. The fructan synthesis activity of the immobilized FTF was similar with that of the free enzyme, and were about 70-80% on fructose basis with substrate at 100~200 g/L. The binding time between the hydroxyapatite and FTF was terminated within 2 h, and the binding capacity of the Type I ($20{\mu}m$) hydroxyapatite was above 60 U of FTF/g of the resin. By immobilization, the FTF stability against proteolysis, was greatly improved by approximately 3-4 fold. Thus, the present study demonstrated that immobilization of FTF on the surface of the hydroxyapatite occurrs in simple reaction and the binding strength is strong enough to produce the fructan.