• Journal of Korea Multimedia Society
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• v.14 no.1
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• pp.54-75
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• 2011

PoC(Push-to-talk Over Cellular) is an integrated technology of group voice calls, video calls and internet based multimedia services. If a PoC user can not participate in the PoC session for various reasons such as an emergency situation, lack of battery capacity, then the user can use the PoC Box which has a similar functionality to the MM Box in the MMS(Multimedia Messaging Service). The RTSP(Real-Time Streaming Protocol) method is recommended to be used when there is a transmission session between the PoC box and a terminal. Since the existing VOD service uses a wired network, the packet size of RTSP-based VOD service is huge, however, the PoC service has wireless communication environments which have general characteristics to be used in RTSP method. Packet loss in a wired communication environments is relatively less than that in wireless communication environment, therefore, a buffering latency occurs in PoC service due to a play-out delay which means an asynchronous play of audio & video contents. Those problems make a user to be difficult to find the information they want when the media contents are played-out. In this paper, the following techniques and methods were proposed and their performance and superiority were verified through testing: cross-over dual reception buffering technique, advance partition multi-reception buffering technique, and on-demand multi-reception buffering technique, which are designed for effective picking up of information in media content being transmitted in short amount of time using RTSP when a user searches for media, as well as for reduction in playback delay; and same-priority packetization transmission method and priority-based packetization transmission method, which are media data packetization methods for transmission. From the simulation of functional evaluation, we could find that the proposed multiple receiving buffering and packetizing methods are superior, with respect to the media retrieval inclination, to the existing single receiving buffering method by 6-9 points from the viewpoint of effectiveness and excellence. Among them, especially, on-demand multiple receiving buffering technology with same-priority packetization transmission method is able to manage the media search inclination promptly to the requests of users by showing superiority of 3-24 points above compared to other combination methods. In addition, users could find the information they want much quickly since large amount of informations are received in a focused media retrieval period within a short time.

• Journal of Korea Game Society
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• v.12 no.3
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• pp.59-68
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• 2012

This paper describes the design and implementation of a network-adaptive N-screen game system to be used in cloud computing. The system we are considering needs to generate game video in a cloud server and transmit the video to multiple game devices over an in-home wireless network via a home game server. It is difficult to support multiple screens which have different resolutions with a single bitstream of game video. Therefore, we developed a new network-adaptive game-video extraction and transmission method using (1) scalable video coding and (2) Raptor code techniques. The simulation, conducted with real game-video, verified the efficiency of the proposed video streaming system.

• ETRI Journal
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• v.32 no.6
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• pp.854-862
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• 2010

One-way delay variation (OWDV) has become increasingly of interest to researchers as a way to evaluate network state and service quality, especially for real-time and streaming services such as voice-over-Internet-protocol (VoIP) and video. Many schemes for OWDV measurement require clock synchronization through the global-positioning system (GPS) or network time protocol. In clock-synchronized approaches, the accuracy of OWDV measurement depends on the accuracy of the clock synchronization. GPS provides highly accurate clock synchronization. However, the deployment of GPS on legacy network equipment might be slow and costly. This paper proposes a method for measuring OWDV that dispenses with clock synchronization. The clock synchronization problem is mainly caused by clock skew. The proposed approach is based on the measurement of inter-packet delay and accumulated OWDV. This paper shows the performance of the proposed scheme via simulations and through experiments in a VoIP network. The presented simulation and measurement results indicate that clock skew can be efficiently measured and removed and that OWDV can be measured without requiring clock synchronization.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.111-118
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• 2009

Recently many global enterprises build RTLS system for their environments. RTLS is used to detect object at real tim e. Unlike RFID, RTLS tags are read automatically and continuously, independent of the process that moves the tags. The proposed functionality of standard API has two problems. When middleware provides data to application, it sends a huge amount of data that may be useless. When only an application requests for data, the middleware replies result data in synchronous mode. This paper proposes a method to reduce an amount of data transferring from middleware to application and an addition communication mode to support real-time event processing in the middleware. Also, we designed and implemented an RTLS middleware applying the proposed methods.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1073-1076
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• 2011

In this paper, we propose a scalable random access scheme in SVC based DASH service that enables random access support not only for base layer of SVC but also for enhancement layers. The proposed method includes extension of segment index box ('sidx') from DASH standard, as well as new RAP Synchronization Box ('raps'). Since the proposed scheme provides random access service for movie fragments with SVC encoded video layers, adaptive scalable random access service is possible.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.80-84
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• 2005

Many important properties in colloidal systems are usually determined by surface charge ($\zeta$-potential) of the contacted solid surface. In this study, $\zeta$-potential of glass $\mu$-channel was evaluated from the electro-osmotic velocity distribution. The electro-osmotic velocity inside a glass $\mu$-channel was measured using a micro-PIV velocity field measurement technique. This evaluation method is more simple and easy to approach, compared with the traditional streaming potential technique. The $\zeta$-potential in the glass $\mu$-channel was measured for two different mole NaCl solutions. The effect of an anion surfactant, sodium dodecyl sulphate (SDS), on the electro-osmotic velocity and $\zeta$-potential in the glass surface was also studied. In the range of $0\∼6$mM, the surfactant SDS was added to NaCl solution in four different mole concentrations. As a result, the addition of SDS increases $\zeta$-potential in the surface of the glass $\mu$-channel. The measured $\zeta$-potential was found to vary from-260 to-70mV. When negatively charged particles were used, the flow direction was opposite compared with that of neutral particles. The $\zeta$-potential has a positive sign for the negative particles.

• Journal of Korea Multimedia Society
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• v.23 no.5
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• pp.700-709
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• 2020

With the development of virtual reality (VR)-related technology and the advent of the 5G era, VR-based streaming games or content have been developed and transmitted at high speed. Although VR technology is also being applied in education, health care, manufacturing, and production fields, its main application is for entertainment. VR technology has been developed based on hardware and various contents have been developed accordingly; however, the number of VR content with high entertainment value is insufficient, and there are primarily hands-on contents. In this paper, we propose a method for developing an writing tool that can enhance the productivity in the development and editing of VR content and create VR contents based on a timeline by reflecting the storytelling rather than by a simple empirical type to solve the bias in content style. The proposed VR content writing tool is expected to increase the productivity in VR content development and contribute to the creation of various styles of content. Its implementation can enable developers to create specific stories in a timeline and support several animation effects.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.289-293
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• 2011

In our previous research, we proposed a MOST GATEWAY system for organically connected to the network MOST150 and MOST 25 and we proposed a simulation design method for performance analysis of Scheduling Algorithm in MOST GATEWAY system. Therefore in this paper, after comparing the performance among the existing scheduling algorithm methods in MOST25 and MOST150 Networks, we use NS-2 simulator in order to analyze the performance. Finally, we present an improvement scheme of the efficiency and scalability.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.277-284
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• 2012

In this paper, we analyzed various noise in the video stream system that have largely influence on EMI noise. We presented the remedy for these various noises and then designed the wireless video streaming system for a vehicle. To minimize EMI noise, we derived the improvement of noise characteristic from impedance matching, new design of the inner layer of the PCB line design and new design of high-speed data Interfaces. As a result, the final system showed 40[dBuV/m] and 47[dBuV/m] dB in the each regulation band.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.109-112
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• 2020

Many devices are connected on the internet to give functionalities for interconnected services. In 2020', The number of devices connected to the internet will be reached 5.8 billion. Moreover, many connected service provider such as Google and Amazon, suggests edge computing and mesh networks to cope with this situation which the many devices completely connected on their networks. This paper introduces the current state of the introduction of the wireless mesh network and edge cloud in order to efficiently manage a large number of nodes in the exploding Internet of Things (IoT) network and introduces the existing Network Time Protocol (NTP). On the basis of this, we propose a relatively accurate time synchronization method, especially in heterogeneous mesh networks. Using this NTP, multiple time coordinators can be placed in a mesh network to find the delay error using the average delay time and the delay time of the time coordinator. Therefore, accurate time can be synchronized when implementing IoT, remote metering, and real-time media streaming using IoT mesh network.