• Journal of Korea Multimedia Society
• /
• v.13 no.3
• /
• pp.349-358
• /
• 2010

Adaptability is an important issue in video streaming over mobile environments, since the clients may request videos with great differences in their workload. In this paper, we propose the issues in limited bandwidth scheduling for efficient MPEG-4 video stream transmission over a mobile or wireless network. In the phase of admission control, the amount of bandwidth allocated to serve a video request is the mean bandwidth requirement of its requested video. The dynamic allocation of bandwidth in the phase of scheduling depends on the playback buffer levels of the clients with an objective to make it more adaptive to the playback situation of individual clients. In the proposed RTA scheduling protocol, more bandwidth may be allocated temporarily to the client whose buffer level is low. By employing the buffer level based scheduling policy, this protocol attempts to maximize the real-time performance of individual playback while minimizing the impact of transient overloading. Extensive simulation experiments have been performed to investigate the performance characteristics of the RTA protocol as comparing with BSBA protocol. This RTA protocol shows the better performance by transferring more frames than BSBA protocol.Computer simulations reveals that the standard deviation of the bit rate error of the proposed scheme is 50% less than that of the conventional method.

• Journal of KIISE:Databases
• /
• v.29 no.6
• /
• pp.477-491
• /
• 2002

The broadcast environment has asymmetric communication aspect that is typically much greater communication bandwidth available from server to clients than in the opposite direction. In addition, mobile computing systems generate mostly read-only transactions from mobile clients for retrieving different types of information such as stock data, traffic information and news updates. Since previous concurrency control protocols, however, do not consider such a particular characteristics, the performance degradation occurs when previous schemes are applied to the broadcast environment. In this paper, we propose optimistic concurrency control based on timestamp interval for broadcast environment. The following requirements are satisfied by adapting weak consistency that is the appropriate correctness criterion of read-only transactions: (1) the mutual consistency of data maintained by the server and read by clients (2) the currency of data read by clients. We also adopt the timestamp Interval protocol to check the weak consistency efficiently. As a result, we improved a performance by reducing unnecessary aborts and restarts of read-only transactions caused when global serializability was adopted.

• Korean Journal of Construction Engineering and Management
• /
• v.15 no.2
• /
• pp.122-131
• /
• 2014

As plant market grows up, client demands to increase quality, technology and to reduce construction period. Due to the vast scale of the construction site and complexity of process, plant project can have some problems of communication among the project participants, the duplication of work, errors and rework. As a result those cause more costs, delay the construction schedule and reduce productivity and quality. Therefore, real-time communication between participants and real-time sharing of information such as material, equipment and construction are required in plant project site. This research aims to propose process and develop system using NFC(Near Field Communication) technology and augmented reality technology with mobile device for plant construction site. Administrators and operators are able to work efficiently using proposed process and system which create an environment designed to share and deliver information such as material, construction information.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.522-525
• /
• 2006

Recently, mobile devices support multi-functions such as 3D game, wireless internet, moving pictures, DMB, GPS, and PMP. Bigger size of display device is indispensable to support these functions and higher speed of the interface is needed. However, conventional parallel interfaces between processor and display nodule are not competent enough for that high speed transfers. High-speed serial interface is beginning to appear as an alternative for parallel interface. The advantages of the serial interface are high bandwidth, small number of interconnections, low-power consumption, and good quality of electro-magnetic interference. In this paper, we implement serial interface and use it for a display module. LVDS is used for PHY layer and a defined packet is used for link layer. The feature of the implemented serial interface is the reduced number of interconnections with enough bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.7
• /
• pp.1379-1385
• /
• 2009

We propose a low-power and high-speed client receiver for a mobile display digital interface (MDDI) newly in this paper. The low-power receiver is designed such that bias currents, sink and source currents, are insensitive to variations of power supply, process, temperature, and common-mode input voltage (VCM) and is able to operate at a rate of 450Mbps or above under the conditions of a power supply range of 3.0 to 3.6Vand a temperature range of -40 to 85$^{\circ}$C. And it is confirmed by a simulation result that the current dissipation is less than 500${\mu}$A. A test chip is manufactured with the Magna chip 0.35${\mu}$m CMOS process. When a test was done, the data receiver and data recovery circuits are functioning normally.

• Journal of KIISE:Databases
• /
• v.28 no.4
• /
• pp.715-722
• /
• 2001

Mobile computing has become a reality thank to the convergence of two technologies :powerful portable computers and the wireless networks. The restrictions of wireless network such as bandwidth and energy limitations make data broadcasting an attractive data communication method. This paper addresses the clustering of wireless broadcast data for multipoint queries. By effective clustering of broadcast data the mobile client can access the data on the air in short latency In the paper we define the data affinity and segment affinity measures. The data affinity is the degree that two data objects are accessed by queries, and the segment affinity is the degree that two sets of data (i.e segments) are accessed by queries Our method clusters data objects based on data and segment affinity measures we show that the performance of our method is scarcely infuenced by the growth of the number of queries.

• Journal of the HCI Society of Korea
• /
• v.13 no.4
• /
• pp.15-23
• /
• 2018

A lot of games are supposed to play through controller operations, such as mouse and keyboard rather than user's physical movement. These games have limitation that causes the user lack of movement. Therefore, this study will solve the problems that these traditional game systems have through the development of a motion-producing system, and provide users more realistic system. It recognizes the user's position in a given space and provides a mobile augmented reality system that interacts with virtual game characters. It uses augmented reality technology to make users feel as if virtual characters exist in real space and it designs a mobile game system that uses armband controllers that interact with virtual characters.

• Journal of Korea Spatial Information System Society
• /
• v.3 no.1 s.5
• /
• pp.117-126
• /
• 2001

We have developed the Mobile Multi Sensor System(MMSS) for the data construction of 4S application and for basic technology acquisition of mobile mapping system in Korea. Using this MMSS, we will collect the information of road and road facilities for DB creation and also construct the Digital Elevation Model(DEM) as ancillary data in urban area. The MMSS consist of the integrated navigation sensor, DGPS & IMU, and digital CCD camera set. In the S/W aspect, we developed the post-processing components for extracting the 3D coordinate information (Spatial Information) and the client program for the MMSS user group. In this paper, we will overview the MMSS constitution and post-processing program, and introduce the utilization plan of MMSS.

• Journal of Korea Multimedia Society
• /
• v.17 no.8
• /
• pp.1033-1040
• /
• 2014

Recently, the concept of mobile content service has changed from providing unilaterally contents for single-device to providing same contents for multi-device. This service should be able to provide diverse contents for multi-devices without platform and specification of multi-device. In this study, we propose a bridge technique of heterogeneous smart platform supporting social immersive game. It is possible to access social immersive game by using a multi-platform bridge. To achieve this, we explain techniques of device connection and data transmission between heterogeneous devices using server-client structure and UPnP. It provides an immersive game environment for multi-user, which is able to play in a public place using big screen.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1485-1488
• /
• 2003

This paper proposes a wireless EMG-based human-computer interface (HCI) for persons with disabilities. For the HCI, four interaction commands are defined by combining three elevation motions of shoulders such as left, right and both elevations. The motions are recognized by comparing EMG signals on the Levator scapulae muscles with double thresholds. A real-time EMG processing hardware is implemented for acquiring EMG signals and recognizing the motions. To achieve real-time processing, filters such as high- and low-pass filter and band-pass and -rejection filter, and a full rectifier and a mean absolute value circuit are embedded on a board with a high speed microprocessor. The recognized results are transferred to a wireless client system such as a mobile robot via a Bluetooth module. From experimental results using the implemented real-time EMG processing hardware, the proposed wireless EMG-based HCI is feasible for the disabled.