• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.12
• /
• pp.2976-2983
• /
• 2013

Interest in reducing standby power is increasing because of electric power shortages. Most of electric equipment are in standby state that does not use a function of the original, most electronic devices consume a lot of electric power even in standby mode. In many countries, research on the smart plug is advanced in order to prevent power consumption due to standby state. However, due to the nature of the function, expensive in many case. These smart plugs would be to cut the standby power using motion detecting sensor or pattern control of the user. Theses features have no advantages because of malfunction of motion detecting sensor and in accordance with the diversification ot user's pattern. In this study, developing a multi-smart plug system that linked with bluetooth function of user's smart phone. Using smart phone bluetooth function, determination of the position of the user. The suggestion smart plug cutting the standby power of the electronic apparatus. It was confirmed that it is able to reduce the power consumption according to the location of the user.

• Journal of Digital Convergence
• /
• v.16 no.11
• /
• pp.495-500
• /
• 2018

This study examined the factors that can enhance the continuity of user experience in multi - device environment. First of all, regarding the structural difference and continuity of tasks, functional differences such as OS difference according to the characteristics of cross media, use of mouse and touch gesture were found to interfere with continuity. To increase continuity, metaphor and ambience To increase relevance and visibility. In the continuity part of visual memory and cognition, familiarity was given by the identity and similarity of visual perception elements, and it was found that familiarity factors are closely related to continuity. Finally, for the continuity of the user experience, we can see that the visibility factors as well as the meaning and layout consistency of the information are factors for the continuity of the user experience. Based on this, it was found that familiarity, consistency, and correlation were significant influences on continuity dimension of user experience, but visibility did not have a significant effect on continuity when regression analysis was conducted as factors of familiarity, consistency, correlation and visibility.

• Journal of Digital Convergence
• /
• v.16 no.11
• /
• pp.465-470
• /
• 2018

This study investigated how layouts can be arranged to improve the user experience in response to changes in the size of responsive webs in a multi - device environment. The layout elements of the responsive web are largely divided into a header, a main concept image, a main content, a sub-content, and a footer. As the screen becomes smaller, the use of drawers and the menu of the scrolling menus rather than the vertical menus will help improve the user experience. The main concept image should be consistent and not lose readability through the use of system fonts. The main content and the sub content should be prevented from being long in the vertical scroll, and the card UI, the table list and the grid list could be alternatively presented for this purpose. Another problem with vertical scrolling is that the placement of user-selectable menus, such as more or new content corrections, is helpful in improving the user experience.

• Journal of the Korea Society of Computer and Information
• /
• v.29 no.7
• /
• pp.191-198
• /
• 2024

In this paper, we proposes a user management system for efficient operation of the combat system within naval ship. Recently, naval ships have seen performance enhancements through various sensors, features, and continuous system development. This progress in the system has led to an increase in multi-funstion consoles that can manipulate various sensors and features within naval ship, consequently increasing the number of operators for these consoles. Therefore, a user management system that can control and manage multi-function consoles and operators in real-time is necessary for efficient management within naval ship. This paper suggests a user management system that can effectively manage the real-time situation of users accessing multi-function consoles. Additionally, a parallelization method using GPUs to reduce the CPU workload in operating various functions of the combat system is proposed. The proposed user management system has shown a performance improvement where the response time decreased by approximately 82% and the occupancy reduced by approximately 20% compared to the method using CPUs.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.11A
• /
• pp.1113-1119
• /
• 2006

For a multi-user OFDM system in mobile channels which requires low-complexity in adaptive resource allocations, resource allocation algorithm using multi-threshold is proposed. The allocation scheme, which is performed by the multi-threshold values in descending order, considers only subcarriers over each threshold level. Moreover, some subcarriers with the lowest channel gain can be· removed in the present threshold level within the constraint of satisfaction of the required data rate, in order to allocate them to the other users when the allocation process of next threshold is executed. As a result, the proposed bandwidth and subcarrier algorithm has better system performances than the conventional allocation schemes in terms of required power and processing time, which is expected as a technique that improves the spectral efficiency of OFDM systems in a mobile environment.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.9
• /
• pp.3335-3356
• /
• 2015

In this paper, we analyze the connectivity of cognitive radio ad-hoc networks in a log-normal shadow fading environment. Considering secondary user and primary user's locations and primary user's active state are randomly distributed according to a homogeneous Poisson process and taking into account the spectrum sensing efficiency of secondary user, we derive mathematical models to investigate the connectivity of cognitive radio ad-hoc networks in three aspects and compare with the connectivity of ad-hoc networks. First, from the viewpoint of a secondary user, we study the communication probability of that secondary user. Second, we examine the possibility that two secondary users can establish a direct communication link between them. Finally, we extend to the case of finding the probability that two arbitrary secondary users can communicate via multi-hop path. We verify the correctness of our analytical approach by comparing with simulations. The numerical results show that in cognitive radio ad-hoc networks, high fading variance helps to remarkably improve connectivity behavior in the same condition of secondary user's density and primary user's average active rate. Furthermore, the impact of shadowing on wireless connection probability dominates that of primary user's average active rate. Finally, the spectrum sensing efficiency of secondary user significantly impacts the connectivity features. The analysis in this paper provides an efficient way for system designers to characterize and optimize the connectivity of cognitive radio ad-hoc networks in practical wireless environment.

• Journal of the Korea Computer Graphics Society
• /
• v.4 no.1
• /
• pp.67-77
• /
• 1998

In this paper we describe a development of a multi user game using 3D graphics and multicasting. First, we represent a virtual reality world by 3D graphics technology. Next, we use computer communication technology for the purpose of interaction among multi users. As a result, multi users share 3D graphics objects and play games. The goal of this paper is a development of a system that enables multi users to play games sharing a virtual world represented by 3D graphics. We use the OpenInventor library and C++ language for 3D graphics scene representation, and IP multicasting protocols for computer communication. The system allows to use Polhemus Fastrak 3D input device that recognizes the 3D position and 3D orientation. As an example we present a game that demonstrates the effect of piano concert by multi piano players who are distributed in a computer network.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.8A
• /
• pp.775-783
• /
• 2006

In this paper, the new technique combining beamforming with space-time coding is proposed for an orthogonal frequency division multiplexing(OFDM) system with multi-input multi-output(MIMO). When MIMO-OFDM system is employing Nt(the number of transmitterantenna) beamfomers and one S-T decoder at Nr receiver antennas, Nt signals removed CCI are outputted at the beamformer and then diversity gain can be got through space-time decoding. As the proposed technique can reduce cochannel interference and get diversity gain in the multi-user environment, the performance of MIMO-OFDM system is very improved. BER performance improvement and convergence behavior of the proposed approach are investigated through computer simulation by applying it to MIMO-OFDM system in the multi-user environment.

• Journal of the Korea Computer Graphics Society
• /
• v.24 no.3
• /
• pp.11-20
• /
• 2018

This study proposes collaboration based multi-user interaction to provide improved presence and satisfying experience to multiple HMD users in immersive virtual reality. The core of the proposed multi-user interaction is to present the direction in which HMD users in virtual reality environment can interact through communication and collaboration with each other based on their separate roles and behaviors. Each user in the virtual collaborative environment uses a hand to interact with a virtual environment or virtual objects. Based on the basic structure, this study designs methods (synchronization and communication) that can be achieved a common goal together through communication and collaboration. Then, this study creates a virtual reality application of arcade genre that considers communication and collaboration in order to verify whether the proposed multi-user interaction provides improved presence and satisfaction experience. And, the survey experiments are conducted for participants. Through these processes, it is confirmed that the interaction in the proposed immersive virtual collaborative environments provide the presence and experience that is satisfactory to all users.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.1
• /
• pp.39-50
• /
• 2010

In this paper, we analyze and simulate the performance of a tactics mobile communication system based on ultra wide band (UWB) in multi-user interference (MUI) environments. This system adopts a double binary turbo code for forward error correction (FEC). Wireless channel is modeled a modified Saleh and Valenzuela (SV) model. We employ a space time block coding (STBC) scheme for enhancing system performance. System performance is evaluated in terms of bit error probability. From the simulation results, it is confirmed that the tactics mobile communication system based on UWB, which is encoded with the double binary turbo code, can achieve a remarkable coding gain with reasonable encoding and decoding complexity in multi-user interference environments. It is also known that the bit error probability performance of the tactics mobile communication system based on UWB can be substantially improved by increasing the number of iterations in the decoding process for a fixed cod rate. Besides, we can demonstrate that the double binary turbo coding scheme is very effective for increasing the number of simultaneous users for a given bit error probability requirement.