• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.485-488
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• 2005

Most metals are polycrystalline material whose deformation is dominated by the slip system. During the deformation process, orientation of slip systems is rearranged with preferred orientations, leading to deformation-induced crystallographic texture which is called deformation texture. Depending on the texture development, the property of material can be changed. The rate-independent crystal plasticity which is based on the Schmid law as a yield function causes a non-uniqueness in the choice of active slip systems. In this work, to avoid the slip system ambiguity problem, rate-independent crystal plasticity model based on the smooth yield surface with rounded-off corners is adopted. In order to simulate the polycrystalline material under plastic deformation, we employ the Taylor model of polycrystal behavior that all the grains are assumed to be subjected to the macroscopic velocity gradient. Rigid-plastic finite element program based on this rate-independent crystal plasticity is developed to predict the grain-level deformation behavior of FCC metals during metal forming processes. In the finite element calculation, one integration point is considered as a crystalline aggregate which has a number of crystals. Macroscopic behavior of material can be deduced from the behavior of aggregates. As applications, the extrusion processes are simulated and the changes of mechanical properties are predicted.

• Journal of Internet Computing and Services
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• v.4 no.1
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• pp.27-37
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• 2003

This paper presents the Web service generation system using virtual environments and databases. Main features include that the environments and databases are generated and maintained correspondingly. It means that the virtual environments are changed automatically if the databases are updated, and also that the databases are maintained accordingly as the information about the environments are modified at the scene End users can modify the property of the virtual environments in the scene directly using the VRML edit interface, which visualizes the structures of virtual environments. Each object can be accessed through the VRML editor, its property be modified directly, and the information is updated in the database automatically. Web service pages are maintained accordingly. In addition, we define a texture mapping method based on weighted view interpolation using 2 photo images for a scene. A texture mapping interface Is also provided for end users to generate realistic images themselves.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1349-1365
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• 2020

In recent years, in the fields of smart cities and digital twins, research on model generation is increasing due to the advantage of acquiring actual 3D coordinates by using point clouds. In addition, there is an increasing demand for a solid model that can easily modify the shape and texture of the building. In this paper, we propose a method to create a clustered solid building model based on point cloud data. The proposed method consists of five steps. Accordingly, in this paper, we propose a method to create a clustered solid building model based on point cloud data. The proposed method consists of five steps. In the first step, the ground points were removed through the planarity analysis of the point cloud. In the second step, building area was extracted from the ground removed point cloud. In the third step, detailed structural area of the buildings was extracted. In the fourth step, the shape of 3D building models with 3D coordinate information added to the extracted area was created. In the last step, a 3D building solid model was created by giving texture to the building model shape. In order to verify the proposed method, we experimented using point clouds extracted from unmanned aerial vehicle images using commercial software. As a result, 3D building shapes with a position error of about 1m compared to the point cloud was created for all buildings with a certain height or higher. In addition, it was confirmed that 3D models on which texturing was performed having a resolution of less than twice the resolution of the original image was generated.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.1207-1210
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• 2022

2D 이미지로부터 카메라의 위치 정보를 추정할 수 있는 Structure-from-Motion (SfM) 기술과 dense depth map 을 추정하는 Multi-view Stereo (MVS) 기술을 이용하여 2D 이미지에서 point cloud 와 같은 3D data 를 얻을 수 있다. 3D data 는 VR, AR, 메타버스와 같은 컨텐츠에 사용되기 위한 핵심 요소이다. Point cloud 는 보통 VR, AR, 메타버스와 같은 많은 분야에 이용되기 위해 mesh 형태로 변환된 후 texture 를 입히는 Texturing 과정이 필요하다. 기존의 Texturing 방법에서는 mesh의 face에 사용될 image의 outlier를 제거하기 위해 color 정보만을 이용했다. Color 정보를 이용하는 방법은 mesh 의 face 에 대응되는 image 의 수가 충분히 많고 움직이는 물체에 대한 outlier 에는 효과적이지만 image 의 수가 부족한 경우와 부정확한 카메라 파라미터에 대한 outlier 에는 부족한 성능을 보인다. 본 논문에서는 Texturing 과정의 view selection 에서 depth 정보를 추가로 이용하여 기존 방법의 단점을 보완할 수 있는 방법을 제안한다.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.153-158
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• 1998

Since the mid-1990′s, researches on 3D GIS have been regarded as one of main issues both in the academic sites and commercial vendors; recently, some prototyped systems or the first versioned software systems of commercial basis are being reported and released. Unlike conventional 2D GIS, which consists in intelligent structured GIS or desktop GIS, every 3D GIS has its own distinguished features according to data structure-supporting capability, GIS-styled functionality, external database accessibility, interfacing extents with 2D GIS, 3D visualization/texture mapping ability, and so forth. In this study, technical aspects related to system development, SERI-Web3D GIS ver. 1.2, are explained. Main features in this revised 3D GIS can be summarized: 2-tier system model(client-server), VGFF(Virtual GIS File Format), internal GIS import, Feature manager(zoning, layering, visualization evironment), Scene manager(manage 3D geographic world), Scene editor, Spatial analyzer(Intersect, Buffering, Network analysis), VRML exporter. While, most other 3D GISes or cartographic mapping systems may be categorized into 3D visualization systems handling terrain height-field processing, 2D GIS extension modules, or 3D geometric feature generation system using orthophoto image: actually, these are eventually considered as several parts of "real 3D GIS". As well as these things, other components, especially web-based 3D GIS, are being implemented in this study: Surface/feature integration, Java/VRML linkage, Mesh/Grid problem, LOD(Level of Detail)/Tiling, Public access security problem, 3-tier architecture extension, Surface handling strategy for VRML.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.885-892
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• 2013

In this paper, we propose a method of effectively segmenting character regions by using texture and depth features in 3D stereoscopic images. The suggested method is mainly composed of four steps. The candidate character region extraction step extracts candidate character regions by using texture features. The character region localization step obtains only the string regions in the candidate character regions. The character/background separation step separates characters from background in the localized character areas. The verification step verifies if the candidate regions are real characters or not. In experimental results, we show that the proposed method can extract character regions from input images more accurately compared to other existing methods.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.533-546
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• 2014

This paper presents a method for a hybrid (color and depth) camera system construction using a photogrammetric technology. A TOF depth camera is efficient since it measures range information of objects in real-time. However, there are some problems of the TOF depth camera such as low resolution and noise due to surface conditions. Therefore, it is essential to not only correct depth noise and distortion but also construct the hybrid camera system providing a high resolution texture map for generating a 3D model using the depth camera. We estimated geometry of the hybrid camera using a traditional relative orientation algorithm and performed texture mapping using backward mapping based on a condition of collinearity. Other algorithm was compared to evaluate performance about the accuracy of a model and texture mapping. The result showed that the proposed method produced the higher model accuracy.

• Journal of the Korean Society of Food Culture
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• v.31 no.3
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• pp.250-260
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• 2016

This study was conducted to determine the reasonable soaking period of glutinous rice for laver Bugak (Korean traditional fried dishes) processing and to identify the sensory characteristics of three kinds of laver Bugak made with different starch pastes: GRice_1d using glutinous rice soaked for 1 day; GRice_7d using glutinous rice fermented for 7 days; and Wheat using flour. Descriptive analysis was performed by 10 trained panelists, and the 92 consumers evaluated the overall acceptance (OL), acceptance of appearance (APPL), odor (ODL), flavor (FLL), and texture (TXTL) of the samples using a 9-point hedonic scale. From the measurement result by scanning electron microscope (SEM), there were differences in the surface characteristics among soaking period for 1 day and 7 days. Ten panelists were trained, and they evaluated the appearance, odor/aroma, flavor/taste, texture/mouth feel, and after taste attributes of these samples. 36 attributes were generated by panelists and 12 attribute were significantly different across products (p<0.05). It was found that the Grice_7d sample was characterized by mouthfeel of crispiness and uniformity of bubbles, and the Wheat sample was characterized by surface of roughness, mouthfeel of crispiness and adhesiveness, relatively. And the Grice_1d sample was characterized by surface of roughness, mouthfeel of roughness, hardness, cohesiveness, toughness, and adhesiveness.

• Journal of Korea Multimedia Society
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• v.9 no.8
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• pp.950-962
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• 2006

Recently, there have been increased many 3 dimensional graphic applications in Internet. Thus, a growing number of methods have been proposed for retrieving 3-D graphic data using their 3D features such as color, texture, shape, and spacial relations. However, few researches focus on 3D graphic modeling and database storage techniques. In this paper, we introduce a system that can store 3D graphics data modeled by XML-based 3D graphics markup language, 3DGML, and support content-based retrievals on 3D data by using SQL. We also present a mapping technique of 3DGML to relational database. The mapping process includes the extraction of semantic information from 3DGML and translate it into relational format. Finally, we show examples of SQL queries which use the 3D information contained in a 3D scene such as objects, 3D features, descriptions and scene-object component hierarchy.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.25-27
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• 2002

본 논문에서는 3차원 그래픽의 래스터라이제이션 단계에서 발생하는 메모리 트래픽 문제를 해결하기 위해 사용되는 텍스처 및 픽셀 캐쉬에 대한 성능을 분석하였다. 이를 위해 화면의 해상도, 컬러 정보, 깊이 정보 및 캐쉬 구성의 변화에 따른 이들 캐쉬의 성능변화를 살펴보았으며 실험결과 텍스처 캐쉬와 픽셀 캐쉬의 설계 시에 블록 크기에 의한 영향이 매우 중요함을 알 수 있었다. 특히 픽셀 캐쉬의 경우에는 시간적 지역성은 거의 없으며 매우 큰 공간적 지역성을 보이므로 이를 잘 반영할 수 있는 캐쉬 구조가 필요하다.