• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.574-580
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• 2006

Anisotropy has an important effect on the strain distribution in aluminum alloy sheet forming, and it is closely related to the thinning and formability of sheet metals. Thus, the anisotropy of the material should be properly considered for the realistic analyses of aluminum sheet forming processes. For this, anisotropy can be approached in two different scales: phenomenological and microstructural (polycrystal) models. Recent anisotropic models (Yld2000-2d; Barlat et al.[1] 2003, Cuitino et al.[2] 1992) were employed in this work. For the simulation using shell element, the method which can impose plane stress condition in the polycrystal model is developed. Lankford values and yield stress ratios are calculated along various directions. As planar anisotropic behavior, a circular cup deep drawing simulation was carried out to compare the phenomenological and microstructure models in terms of earing profile.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.130-139
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• 2023

With the increasing popularity of computer-generated virtual influencers, the trend is rising especially on social media. Famous virtual influencer characters Lil Miquela and Imma were all created by CGI graphics workflows. The process is typically a linear affair. Iteration is challenging and costly. Development efforts are frequently siloed off from one another. Moreover, it does not provide a real-time interactive experience. In the previous study, a real-time graphic workflow was proposed for the Digital Actor Hologram project while the output graphic quality is less than the results obtained from the CGI graphic workflow. Therefore, a real-time engine graphic workflow for Virtual Influencers is proposed in this paper to facilitate the creation of real-time interactive functions and realistic graphic quality. The real-time graphic workflow is obtained from four processes: Facial Modeling, Facial Texture, Material Shader, and Look-Development. The analysis of performance with real-time graphical workflow for Digital Actor Hologram demonstrates the usefulness of this research result. Our research will be efficient in producing virtual influencers.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.399-401
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• 2024

본 논문에서는 텍스처 합성 기술을 활용하여 가상의 거품 패턴 텍스처를 생성하기 위한 합성 데이터 구축 방법을 소개한다. 물리 기반 유체 시뮬레이션에서 거품 표현은 2차 효과(Secondary effects)로 분류되며, 그만큼 계산량이 큰 작업이다. 게임 업계에서는 저사양 디바이스에서도 실시간으로 게임이 실행되어야 하므로 상대적으로 계산량이 큰 물리 기반 시뮬레이션을 통해 거품을 표현하기 어렵다. 대부분 사용자가 임의로 그린 거품 패턴을 화면에 매핑하여 적은 계산량을 통해 거품을 표현하지만, 시뮬레이션을 통해 만들어진 데이터가 아니기 때문에 품질을 보장하기 어렵다. 본 논문에서는 물리 기반 시뮬레이션을 통해 만들어진 거품 패턴을 텍스처 합성 기술을 통해 재생산(Reproduction)함으로써 수작업으로 그린 거품 패턴에서는 표현하기 어려운 고품질 거품 패턴 텍스처를 만들어 낸다.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.5
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• pp.245-256
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• 2002

Shadows are important elements in producing a realistic image. Generation of exact shapes and positions of shadows is essential in rendering since it provides users with visual cues on the scene. It is also very important to be able to create soft shadows resulted from area light sources since they increase the visual realism drastically. In spite of their importance. the existing shadow generation algorithms still have some problems in producing realistic shadows in real-time. While image-based rendering techniques can often be effective1y applied to real-time shadow generation, such techniques usually demand so large memory space for storing preprocessed shadow maps. An effective compression method can help in reducing memory requirement, only at the additional decoding costs. In this paper, we propose a new image-barred shadow generation method based on image warping. With this method, it is possible to generate realistic shadows using only small sizes of pre-generated shadow maps, and is easy to extend to soft shadow generation. Our method will be efficiently used for generating realistic scenes in many real-time applications such as 3D games and virtual reality systems.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.78-85
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• 2012

This paper proposes an efficient algorithm to develop a 3D terrain tools which is essential in the development of 3D computer games. In particular, this paper proposes a cross detection technique to improve picking speed. In other words, this paper proposes a more efficient cross detection technique consisting of a ray and a parallelogram than a cross detection technique consisting of a ray and a triangle. So, we can confirm the faster picking speed. This paper uses a picking example among DirectX SDK samples to test it. In addition, this paper compares the number of function calls for cross detection using the existing techniques and the proposed technique. As a result, in this paper the proposed technique has fallen off to about a 50 percent than the existing techniques. And if it is calculated by times, in this paper the proposed technique was reduced to 1 to 2 seconds than the existing techniques. Additionally, in this paper 3D terrain tools are provide more improved algorithms for features such as texture splatting, height map control, object arrangement and realistic water effect. So, 3D terrain tools is available efficient in the development of real 3d computer games.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.355-361
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• 2006

In large scale environments like airport, museum, large warehouse and department store, autonomous mobile robots will play an important role in security and surveillance tasks. Robotic security guards will give the surveyed information of large scale environments and communicate with human operator with that kind of data such as if there is an object or not and a window is open. Both for visualization of information and as human machine interface for remote control, a 3D model can give much more useful information than the typical 2D maps used in many robotic applications today. It is easier to understandable and makes user feel like being in a location of robot so that user could interact with robot more naturally in a remote circumstance and see structures such as windows and doors that cannot be seen in a 2D model. In this paper we present our simple and easy to use method to obtain a 3D textured model. For expression of reality, we need to integrate the 3D models and real scenes. Most of other cases of 3D modeling method consist of two data acquisition devices. One for getting a 3D model and another for obtaining realistic textures. In this case, the former device would be 2D laser range-finder and the latter device would be common camera. Our algorithm consists of building a measurement-based 2D metric map which is acquired by laser range-finder, texture acquisition/stitching and texture-mapping to corresponding 3D model. The algorithm is implemented with laser sensor for obtaining 2D/3D metric map and two cameras for gathering texture. Our geometric 3D model consists of planes that model the floor and walls. The geometry of the planes is extracted from the 2D metric map data. Textures for the floor and walls are generated from the images captured by two 1394 cameras which have wide Field of View angle. Image stitching and image cutting process is used to generate textured images for corresponding with a 3D model. The algorithm is applied to 2 cases which are corridor and space that has the four wall like room of building. The generated 3D map model of indoor environment is shown with VRML format and can be viewed in a web browser with a VRML plug-in. The proposed algorithm can be applied to 3D model-based remote surveillance system through WWW.

• Journal of the Korea Society of Computer and Information
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• v.29 no.4
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• pp.63-72
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• 2024

The size of the home interior market is growing rapidly as interest in interiors and self-interiors has increased due to the recent rapid increase in single-person households. Most of the Bathroom remodeling is done by requesting an offline interior contractor and then visually checking it in the final completion stage, so it is not easy to re-construct even if the customer is dissatisfied. Therefore, this study developed an immersive virtual reality-based Bathroom self-remodeling system that can visually check space and design from the design stage to the final stage by incorporating VR technology to feel realistic in virtual reality. The bathroom structure may select the basic structure of the predefined bathroom space or freely set the size of the bathroom space. For furniture items, you can choose the washbasin, toilet, bathtub, shower booth that are essential elements of the bathroom and others(mounting rack, trash bin, handle). The tile texture may change the texture of the selected tile at a desired wall position by selecting various textures. In particular,, the texture of the wall tile can be varied by selecting horizontal, vertical and inclined directions at the desired angle according to the needs of the user and the contractor. As a future research project, this system will enable indoor sharing between users who are physically far away in real-time, allowing direct experience in virtual spaces, connection to purchases, and request estimates.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.238-246
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• 2018

The production of hyper-realistic digital rendering images has been available due to radical improvements of recent digital rendering and CGI (Computer-Generated Imagery) software technologies. The photorealism of digital architectural rendering images requires further studies and discussions in that architectural visualization becomes a foundation of other fields using digital rendering technology, such as movies, games, and VR industry. The principles for achieving photorealism on digital architectural rendering images were re-defined and detailed elements were analyzed through theoretical analysis of the former studies. Four principles were drawn from the architectural rendering images produced by newly-developed technologies: physically-accurate lighting calculations, accurate object geometry representation, realistic material and texture, and characteristics of photography. The sub-elements of those four principles are categorized into either essential or selective for photorealistic imagery and the randomness of the selective elements could explain the variety of photorealistic architectural rendering styles.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.38-48
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• 2007

In this paper, we propose an image-based method for modeling 3D objects with curved surfaces based on the NURBS (Non-Uniform Rational B-Splines) representation. Starting from a few calibrated images, the user specifies the corresponding curves by means of an interactive user interface. Then, the 3D curves are reconstructed using stereo reconstruction. In order to fit the curves easily using the interactive user interface, NURBS curves and surfaces are employed. The proposed surface modeling techniques include surface building methods such as bilinear surfaces, ruled surfaces, generalized cylinders, and surfaces of revolution. In addition to these methods, we also propose various advanced surface modeling techniques, including skinned surfaces, swept surfaces, and boundary patches. Based on these surface modeling techniques, it is possible to build various types of 3D shape models with textured curved surfaces without much effort. Also, it is possible to reconstruct more realistic surfaces by using proposed view-dependent texture acquisition algorithm. Constructed 3D shape model with curves and curved surfaces can be exported in VRML format, making it possible to be used in different 3D graphics softwares.

• 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.