• International Journal of Control, Automation, and Systems
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• v.4 no.1
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• pp.63-69
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• 2006

Problems like poor security, transfer delay or packet loss occur while building network systems that are applied with TCP/TP integrate with data network systems. To solve this problem, this paper proposes the Separated Ethernet, which can give priority to the system, and by using the OPNET Modeler simulator, we will verify its performances.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.218-223
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• 2008

In this paper, we implement several methods to improve an audio collaboration system over IP networks, and then evaluate the performance of the implemented methods. In general, speech and audio quality degrades depending on the characteristics of IP networks such as jitter and packet loss. In order to reduce this quality degradation, we propose a lower bit rate audio delivery scheme using the MPEG-2 AAC (Advanced Audio Coding) audio codec in a viewpoint that a packet loss rate could be reduced by a smaller packet size. In addition, iLBC (Internet Low-Bitrate Codec) and the G.711 packet loss concealment algorithm defined by IEFT and ITU-T, respectively, are applied to a audio collaboration system. RAT (Robust-Audio Tool)[7] is used as a baseline platform for the implementation of the proposed methods. It is shown from the implementation that the implemented MPEG-2 AAC audio codec with a bitrate of 256 kbit/s performs as similar as the uncompressed audio quality with a bitrate of 512 kbit/s, and that iLBC and the G.711 packet loss concealment algorithm can improve speech quality when a packet loss rate is 2~10%.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.1012-1021
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• 2005

This paper describes the design and implementation of an efficient multi-point multimedia conference system using IP grouping. Existing multi-point multimedia conference systems are difficult for multi-user to perform efficient cooperation due to bandwidth limitation for data transmission of video, audio and documentation. In the case that multi-user uses limited bandwidth, smooth cooperation does not accomplish due to transmission delay for the real-time transmission of image and speech data. A hybrid transfer method which is mixed with distributed and centralized methods is used for smooth cooperation, and the network bandwidth is reduced by forming multi-user conference systems of IP grouping in this paper. Also, adaptive image frame variations are used to solve bottleneck effect according to the number of users. An efficient multi-user conference system is designed to support audio quality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.939-954
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• 2013

Korean military is developing the next generation military satellite communications system in order to achieve the requirements of future military satellite communication such as high speed, high capacity, survivability, all IP networking, and on-the-move. In this paper, we survey and analyze the research interests about optimal resource allocation and IP networking such as MF-TDMA, random access, satellite IP routing, and PEP. Conventional researches have focused on the increase in channel throughput and efficiency. In addition to these measurements, we consider heterogeneous satellite terminals, full mesh topology, distributed network, anti-jamming, and the like which are the special characteristics of the next generation military satellite communications system. Based on this, we present key research issues and evaluation on the issues by simulation.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.2
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• pp.120-126
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• 2006

In this paper, we propose for improving QoS in hospital wireless network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it has its vulnerability in frequent handoff environment. This handoff state machine using differentiated handoff improves quality of services in Cellular-IP/PRC. Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. When speech quality is secured considering increment of interference to receive in case of suppose that proposed acceptance method grooves base radio station capacity of transfer node is plenty, and most of contiguity cell transfer node was accepted at groove base radio station with a blow, groove base radio station new trench lake acceptance method based on transmission of a message electric power estimate of transfer node be. Do it so that may apply composing PC(Paging Cache) and RC(Routing Cache) that was used to manage paging and router in radio Internet network in integral management and all nodes as one PRC(Paging Router Cache), and add hand off state machine in transfer node so that can manage hand off of transfer node and Roaming state efficiently, and studies so that achieve connection function at node. Analyze benevolent person who influence on telephone traffic in system environment and forecasts each link currency rank and imbalance degree, forecast most close and important lake interception probability and lake falling off probability, GoS(Grade of Service), efficiency of cell capacity in QoS because applies algorithm proposing based on algorithm use gun send-receive electric power that judge by looking downward link whether currency book was limited and accepts or intercept lake and handles and displays QoS performance improvement.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.307-312
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• 2011

In the macro/femto cellular networks, the portion of channels assigned to each cell is a critical factor which sets the stability and the performance of the whole system. To grasp the concrete influence that the channel split portion have on the system, we present the queueing model for IP based macro/femto cellular networks, and find the stability conditions. Additionally we provide the strategy to decide the portion of channels allocated to each cell. Through the experiments, we prove that the proposed strategies operate feasibly in various network environments, and on the basis of these results we discuss the efficient system structure plan.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.7
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• pp.1003-1010
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• 2013

In this paper, TCP/IP based Machine-to-Machine (M2M) communication uses CDMA/GSM network for data communication. This communication method is widely used by offshore moored buoy for data transmission back to the system server. Due to weather and signal coverage, the TCP/IP M2M communication often experiences transmission failure and causing data losses in the server. Data losses are undesired especially for meteorological and oceanographic analysis. This paper discusses a software approach to minimize M2M data losses by handling transmission failure and re-attempt which meant to transmit the data for recovery. This implementation was tested for its performance on a meteorological buoy placed offshore.

• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.261-266
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• 2005

This paper proposes two systems. One is a Home Gateway(HG) which efficiently connects and controls digital appliances in the home network environments. The other is a Management Server(MS) that overcomes the physical limitation of the HG. The HG supports networking modules(TCP/IP for Ethernet, ADSL), home networking functions(HomePNA, IEEE1394 PLC) and telecommunication system(PSTN/SLT, VoIP, Video Communication). The HG is expected to be a core device for the integrated digital home environments. The MS is a dedicated server which manages and controls individual HG, home appliances and HA devices implemented at an area.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1120-1130
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• 2004

Distributed Denial-of-Service(DDoS) attack prevent users from accessing services on the target network by spoofing its origin source address with a large volume of traffic. The objective of IP Traceback is to determine the real attack sources, as well as the full path taken by the attack packets. Existing IP Traceback methods can be categorized as proactive or reactive tracing. Existing proactive tracing scheme(such as packet marking and messaging) prepares information for tracing when packets are in transit. But, these scheme require additional network overhead. In this paper, we propose a "advanced Traceback" mechanism, which is based on the modified Pushback system with secure router mechanism. Proposed mechanism can detect and control DDoS traffic on router and can generate marked packet for reconstructing origin DDoS attack source, by which we can diminish network overload and enhance Traceback performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1614-1620
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• 2009

The overlay multicast that has been recently presented as an alternative for the IP multicast has been getting much persuasion by the system resource and the network bandwidth and the advancement of the network cost. we propose a overlay multi_casting network policy for efficient multimedia services with P2P join scheduling. In order to evaluate the performance of proposed scheme, We test the performance of multi_casting nodes with average join count, the maximum guaranteed waiting time and buffer starvation ratio with similar techniques. The result of simulation shows improved about 15${\sim}$20% of performance.