• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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• pp.65-72
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• 2016

Network virtualization is an emerging technology for solving the rigidity of the physical network infrastructure. The innovative technique virtualizes all resources in the network, including the network links and nodes, and provides a number of virtual networks on a single network infrastructure. In order to realize a virtual network, a thorough and complete monitoring of all resources in the network should be performed firstly. OpenFlow is an open source stack for network virtualization. However, it is impossible to apply OpenFlow to AP-based legacy wireless LAN environment because OpenFlow targets ethernet-based LAN environment. In this paper, we implement an adaptor-styled virtual switch for AP-based wireless LAN through customizing the Open vSwitch which is a virtual switch of OpenFlow. The evaluation test results show that the implemented OpenFlow stack operates successfully. The implemented OpenFlow stack can now be plugged immediately in existing AP-based wireless LAN environment and plays network resource monitoring. In the future, we can develop wireless LAN virtualization applications on the wireless OpenFlow stack.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.783-785
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• 2003

In recent years, the use of video in GIS is considered to be an important subject and many related studies result in VideoGIS. The virtual navigation is an important function that can be applied to various VideoGIS applications. For virtual navigation by video, the following problems must be solved. 1) Because the video route may be not exactly coincided with route that user wants to navigate, parts of several video clips may be required for single navigation. Virtual navigation should allow the user to move from one video to another at the proper position. We suggest the video segmentation method based on geographic data combined with video. 2) From a point to a destination, the change frequency of video must be minimized. The frequent change of video make user to mislead navigation route and cause the wasteful use of computing resource. We suggest methods that structure video segments and calculate weight value of each node and link.

• Journal of Korea Game Society
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• v.19 no.3
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• pp.33-42
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• 2019

This paper is the result of research on how to represent 'Landscape' of Oriental painting in 3D space within virtual reality. Based on the similarities between the characteristics of Oriental painting and virtual reality put together three features of painting and put them into the digital content. For the expression of painting style, we produced texture, represented spaces and shadows as a content development environment, and the view point with helper storytelling.

• Journal of Korean Academy of Dental Administration
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• v.9 no.1
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• pp.44-50
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• 2021

Owing to the Corona virus (COVID-19) crisis, virtual education has been expanded. Accordingly, this study was conducted to determine the direction of oral health education by examining participants' satisfaction with virtual education and educational media preferences. This study collected data from a Naver Form online survey targeting 290 university students across the country, from May 10 to 31, 2021. The collected data were analyzed using IBM SPSS 20.0. According to the data, satisfaction with virtual classes was 3.36 points in 5-point Likert scale, satisfaction factors were reduced commuting time and money expenditure, and the highest dissatisfaction factor was a decrease in lecture concentration. The media platform that most interested students pursing oral health education was YouTube. The oral health education that participants wished to receive through virtual education included how to prevent tooth decay, how to prevent gum disease, and how to brush teeth. In conclusion, it is necessary to develop various media like Zoom, YouTube, and virtual reality programs so that students feel motivated to utilize oral health education and improve oral health.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1452-1455
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• 2021

Recently, point clouds are generated by capturing real space in 3D, and it is actively applied and serviced for performances, exhibitions, education, and training. These point cloud data require post-correction work to be used in virtual environments due to errors caused by the capture environment with sensors and cameras. In this paper, we propose an enhancement technique for 3D point cloud data by applying generative adversarial network(GAN). Thus, we performed an approach to regenerate point clouds as an input of GAN. Through our method presented in this paper, point clouds with a lot of noise is configured in the same shape as the real object and environment, enabling precise interaction with the reconstructed content.

• Journal of the Korea Computer Graphics Society
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• v.8 no.2
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• pp.9-14
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• 2002

In cases of densely occluded urban scenes, it is effective to determine the visibility of scenes, since only small parts of the scene are visible from a given cell. In this paper, we introduce a new visibility preprocessing method that efficiently computes potentially visible objects for volumetric cells. The proposed method deals with general 3D polygonal models and invisible objects jointly blocked by multiple occluders. The proposed approach decomposes volume visibility into a set of point visibilities, and then computes point visibility using hardware visibility queries, in particular HP_occlusion_test and NV_occlusion_query. We carry out experiments on various large-scale scenes, and show the performance of our algorithm.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.205-210
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• 2012

This paper investigated the performance of QoS management using variations of RED parameters in Differentiated Service. Differentiated Service separates packets from a specific traffic by using QoS parameters such as CIR or PIR. A code point is used to mark each packet which is enqueued into each virtual queue. Different RED parameters are configured for virtual queues according to each code point. As the code point value increases, the RED parameters become harsher. To show QoS Management using variations of RED parameters, this paper used the policy model of time sliding window with 2 color marking (TSW2CM). Simulation results using NS-2 showed that the QoS management of a differentiated service can be obtained from using variations of RED parameters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.886-891
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• 2011

Multicast has been a key routing service for efficient data dissemination in underwater acoustic sensor networks. In sensor networks, there are several multicast routing protocol which reflects sensor network nature. However, existing routing scheme was not targeted at underwater acoustic sensor networks which is hard to provide battery continually. Therefore, a specialized routing algorithm is essential for acoustic sensor networks. In this paper, we propose angle aided multicast routing algorithm for decreasing routing computation complexity, including virtual Euclidean Steiner point. Simulation results show better performance than exist routing Position Based Multicast, Geographic Multicast Routing. such as low computation capability and limited power consumption.

• Journal of the Korea Society for Simulation
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• v.27 no.4
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• pp.1-8
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• 2018

The most common way to control a target point using artificial intelligence is through reinforcement learning. However, it had to process complicated calculations that were difficult to implement in order to process reinforcement learning. In this paper, the enhanced Proximal Policy Optimization (PPO) algorithm was used to simulate finding the planned flight trajectory to reach the target point in the virtual environment. In this paper, we simulated how this problem was used to find the planned flight trajectory to reach the target point in the virtual environment using the enhanced Proximal Policy Optimization(PPO) algorithm. In addition, variables such as changes in trajectory, effects of rewards, and external winds are added to determine the zero conditions of external environmental factors on flight trajectory learning, and the effects on trajectory learning performance and learning speed are compared. From this result, the simulation results have shown that the agent can find the optimal trajectory in spite of changes in the various external environments, which will be applicable to the actual vehicle.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.1-8
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• 2014

The virtual avatar is a principal way as media for communicating language and affective feelings in virtual environment. As similar purpose, this study evaluates user's visual feeling according to the changes of iris color and pupil size of virtual avatar which is considered as new factors for representing realistic avatar. Virtual avatars were configured by pupil accommodation and iris color(green, brown). After presenting above image to 32 participants, a questionnaire(18 items) based on previous studies was created, and reported as a 5-point scale. Experimental result showed that the case of adopting pupil accommodation induced more realistic visual feeling of subjects. This result can be regarded as a basis for designing realistic virtual avatar by confirming the effectiveness of pupil accommodation of avatar in terms of representing visual presence.