• Journal of the Korea Computer Graphics Society
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• v.14 no.2
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• pp.9-17
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• 2008

We propose a method to determine camera parameters for character motion, which confiders the motion by itself. The basic idea is to approximately compute the area swept by the motion of the character's links that are orthogonally projected onto the image plane, which we call "Motion Area". Using the motion area, we can determine good fixed camera parameters and camera paths for a given character motion in the off-line or real-time camera control. In our experimental results, we demonstrate that our camera path generation algorithms can compute a smooth moving camera path while the camera effectively displays the dynamic features of character motion. Our methods can be easily used in combination with the method for generating occlusion-free camera paths. We expect that our methods can also be utilized by the general camera planning method as one of heuristics for measuring the visual quality of the scenes that include dynamically moving characters.

• Journal of Korea Game Society
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• v.7 no.3
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• pp.59-66
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• 2007

Ray tracing is one of the classical global illumination methods to generate a photo-realistic rendering image with various lighting effects such as reflection and refraction. However, there are some restrictions on real-time applications because of its computation load. In order to overcome these limitations, many researches of the ray tracing based on GPU (Graphics Processing Unit) have been presented up to now. In this paper, we implement the ray tracing algorithm by J. Purcell and combine it with two methods in order to improve the rendering performance for interactive applications. First, intersection points of the primary ray are determined efficiently using rasterization on graphics hardware. We then construct the acceleration structure of 3D objects to improve the rendering performance. There are few researches on a detail analysis of improved performance by these considerations in ray tracing rendering. We compare the rendering system with environment mapping based on GPU and implement the wireless remote rendering system. This system is useful for interactive applications such as the realtime composition, augmented reality and virtual reality.

• Journal of Broadcast Engineering
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• v.19 no.1
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• pp.14-23
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• 2014

This paper proposed controlling methods for SDN(Software Defined Network) based multiple radio access technology as the solutions of following two issues which were mainly occurred by explosive increasing of video traffic. The first one is a requirement for traffic off-loading caused by 3rd-party video service providers from the mobile network operator's viewpoint. The other one is a provision of high-speed video contents transmission services with low price. Furthermore, the performance evaluation was also conducted on the real test-bed which is composed of OpenStack cloud and SDN technology such as OpenFlow and Open vSwitch. A virtual machine running on the OpenStack provide a video service and the terminal which is able to use multiple radio access technology supports two 2.4GHz WLANs(Wireless Local Area Network) and three 5GHz WLANs, concurrently. Finally, we can get 820Mbps of the maximum transmission speed by using that five WLAN links for the single service at the same time.

• Journal of KIISE:Software and Applications
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• v.32 no.6
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• pp.570-579
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• 2005

Facial expression recognition technology that has potentialities for applying various fields is appling on the man-machine interface development, human identification test, and restoration of facial expression by virtual model etc. Using sequential facial images, this study proposes a simpler method for detecting human facial expressions such as happiness, anger, surprise, and sadness. Moreover the proposed method can detect the facial expressions in the conditions of the sequential facial images which is not rigid motion. We identify the determinant face and elements of facial expressions and then estimates the feature regions of the elements by using information about color, size, and position. In the next step, the direction patterns of feature regions of each element are determined by using optical flows estimated gradient methods. Using the direction model proposed by this study, we match each direction patterns. The method identifies a facial expression based on the least minimum score of combination values between direction model and pattern matching for presenting each facial expression. In the experiments, this study verifies the validity of the Proposed methods.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.181-188
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• 2005

Chinese Postman Problem (CPP) is a problem that finds a shortest tour traversing all edges or arcs at least once in a given network. The Chinese Postman Problem on Mixed networks (MCPP) is a Practical generalization of the classical CPP and it has many real-world applications. The MCPP has been shown to be NP-complete. In this paper, we transform a mixed network into a symmetric network using virtual arcs that are shortest paths by Floyd's algorithm. With the transformed network, we propose a Genetic Algorithm (GA) that converges to a near optimal solution quickly by a multi-directional search technique. We study the chromosome structure used in the GA and it consists of a path string and an encoding string. An encoding method, a decoding method, and some genetic operators that are needed when the MCPP is solved using the Proposed GA are studied. . In addition, two scaling methods are used in proposed GA. We compare the performance of the GA with an existing Modified MDXED2 algorithm (Pearn et al. , 1995) In the simulation results, the proposed method is better than the existing methods in case the network has many edges, the Power Law scaling method is better than the Logarithmic scaling method.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.532-536
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• 2006

The position of stereoscopic objects is an important parameter to induce three-dimensional effects such as convergence control and image distortions. There are three kinds of stereoscopic cameras : Parallel, Toed-in, and Horizontal-Moving cameras. In this paper we proposed the method for estimating stereoscopic object position with a horizontal-moving camera. In the previous methods, viewing angle ratios are used to estimate the object positions. Our method based on the horizontal movements of the camera to estimate the positions. Using geometrical models of shooting and display we experimented with two methods. Results of experiments showed the distance of stereoscopic objects on virtual screen related to horizontal movement.

• Journal of the Korea Convergence Society
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• v.9 no.2
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• pp.119-124
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• 2018

The augmented reality(AR) technology enables to acquire various image information at the same time by combining virtual image information with the user's viewpoint. These AR technologies have been used to visualize patients' organs and tissues during surgery and diagnosis in the fields of Image-Guide Operation, Surgical Training, and Image Diagnosis by medical convergence, and provides the most effective surgical methods. In this paper, we study the technical features and application methods of each element technology for medical fusion of AR technology. In the AR technology for medical convergence, display, marker recognition and image synthesis interface technology is essential for efficient medical image. Such AR technology is considered to be a way to drastically improve current medical technology in the fields of image guide surgery, surgical education, and imaging diagnosis.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.645-654
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• 1995

A distributed DBMS integrates local schemas that are independently designed, maintained, and managed by different users at each site providing a global virtual schema. This global schema supports users at a specific site to transparently utilize local database at different sites. The security features of the local schema should also not be changed in the global schema integrating security features of each local schema. Researches on the integration of security features into local schema in distributed DBMS environment, however, are very rate. This pater using the multilevel secure object-oriented database model(as the model for the definition of a local schema in distributed environment) which is an extension of the object-oriented models. It also suggests eight integration methods that can maintain the security features of local schemas. The eight methods are classified by the object classes and by relationships among them.

• Journal of Technologic Dentistry
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• v.42 no.1
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• pp.17-25
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• 2020

Purpose: The purpose of this study was to evaluate and compare the accuracy of definitive casts that are fabricated from digital intraoral impression and conventional impression technique. Methods: A master model(ANNA-4, Frasaco GmbH, Tettnang, Germany) with the prepared upper full arch tooth was used. Conventional impression and then stone model(n=10) were produced from this master model, and on the other hands, digital impressions were made with the CS-3600 intraoral scanner(n=10). Six linear measurements were recorded between landmarks, directly on each of the stone models on two occasions by a single examiner. Measurements were made with a digital caliper to the nearest 0.01mm from manual models and with the software(Delcam PowerSHAPE) from the virtual models. The t-student test for paired samples and intraclass correlation coefficient(ICC) were used for statistical analysis. Results: The measurement of two methods showed good reliability. The ICC of the two models were 0.88~0.91(stone model) and 0.94~0.99(digital model). The mean differences to master model for stone model and digital model were 0.10~0.14mm, and 0.14~0.20mm, respectively. Conclusion: The definitive casts obtained with digital intraoral technique model had significantly larger dimensions as compared to those of the stone model. However, the differences to the master model detected appear to provide enough accuracy and reliability for clinical application.

• Archives of design research
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• v.17 no.3
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• pp.51-60
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• 2004

The esthetics of 'grotesque' and its entertaining values have many things in common with the characteristics and properties of animation as a medium of expression. The ways to express grotesque images in animation have expanded its realm of expression with the development of modern image digitalization technologies. The grotesque images that were expressed by the combination of photographs and animations and objet animations have been developing its disharmony in a more realistic manner with full 3D animation technology and realistic motions of virtual characters with motion capture. The subject matter also has become more diverse with the advance of modern scientific civilization. An example is the appearance of Cyborg(cybernetic+organism) characters and the grotesque images in the modern times mainly start to appear in animations dealing with the isolation of human beings among its characteristics. Also, the changes of the expression methods of grotesque images along with the development of visual technology development in the future will transform its methodological forms by changing its expression methods to VR forms and interactive visuals. Thus it is expected that the grotesque images and characteristics will change into a visual genre which emphasizes dehumanization.