• The Journal of the Korea Contents Association
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• v.5 no.5
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• pp.78-84
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• 2005

Various kinds of data broadcasting services can be offered using a return-channel in digital broadcasting TV compared to analog services. In these data broadcasting environments, several data(associated with TV broadcasting programs, or not) are provided to the TV audiences except for audio/video broadcasting data. In this paper, a structure of data manager for data/object carousel, based on data broadcasting protocols, was proposed for data broadcasting services using a return-channel, and were supported to the production technologies of DTV contents. These contents application techniques for DTV will be implemented with this data manager in MPEG2-TS data broadcasts using PID(Packet ID).

• Journal of Information Processing Systems
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• v.2 no.2
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• pp.76-81
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• 2006

A PDA is used mainly for downloading data from a stationary server such as a desktop PC in an infrastructure network based on wireless LAN. Thus, the overall performance depends heavily on the performance of such downloading with PDA. Unfortunately, for a PDA the time taken to receive data from a PC is longer than the time taken to send it by 53%. Thus, we measured and analyzed all possible factors that could cause the receiving time of a PDA to be delayed with a test bed system. There are crucial factors: the TCP window size, file access time of a PDA, and the inter-packet delay that affects the receiving time of a PDA. The window size of a PDA during the downstream is reduced dramatically to 686 bytes from 32,581 bytes. In addition, because flash memory is embedded into a PDA, writing data into the flash memory takes twice as long as reading the data from it. To alleviate these, we propose three distinct remedies: First, in order to keep the window size at a sender constant, both the size of a socket send buffer for a desktop PC and the size of a socket receive buffer for a PDA should be increased. Second, to shorten its internal file access time, the size of an application buffer implemented in an application should be doubled. Finally, the inter-packet delay of a PDA and a desktop PC at the application layer should be adjusted asymmetrically to lower the traffic bottleneck between these heterogeneous terminals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.1-12
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• 2002

In the multimedia CDMA mobile communication service, it is required to support various applications, such as voice, video, file transfer, e-mail, and Internet access, with guaranteed QoS. In the mixed traffic environment ,which consists of voice, stream data, and packet data, we analyze the network where preemptive priority is granted to delay-intolerant voice service and a buffer is offered to delay-tolerant stream data service. And, for best-effort packet data service, the access control by transmission permission probability is applied to obtain prominent throughput. To analyze the multimedia CDMA mobile communication system, we build a 2-dimensional markov chain model about prioritized-voice and stream data services and accomplish numerical analysis in combination with packet data traffic based on residual capacity equation.

• Convergence Security Journal
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• v.23 no.2
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• pp.103-113
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• 2023

In recent years, Unmanned Aerial Vehicles (UAV) have been widely used in various industries. However, as the depend ence on UAV increases rapidly, concerns about the security and safety of UAV are growing. Currently, various vulnerabili ties such as stealing the control right of the UAV or the right to communicate with the UAV in the web application are being disclosed. However, there is a lack of research related to the security of UAV. Therefore, in this paper, a study was conducted to determine whether the packet data was normal or abnormal by collecting packet data of an unmanned aerial vehicle in a HITL(Hardware In The Loop) simulation environment similar to the real environment. In addition, this paper proposes a method for reducing computational cost in the modeling process and increasing the ease of data interpretation, a machine learning-based anomaly detection model that detects abnormal data by learning only normal data, and optimized hyperparameter values.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.3-11
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• 2017

Research and development are being conducted to apply low-power Bluetooth (BLE) technology to IoT (Internet of Things) applications. The characteristic of this application environment is that many piconets can operate in the same space. Therefore, interference between homogeneous networks is likely to occur. In the BLE data channel, adaptive frequency hopping (AFH) scheme is used among the 37 frequency channels, and the master and the slave communicate while changing the carrier frequency. If there are multiple BLE piconets in the same space, there is a risk of frequency collision and packet errors will occur. In this paper, we analyze the packet collision probability due to cochannel interference in multiple asynchronous BLE piconet environments. Specifically, we analyzed packet collision probability according to the number of concurrently operating BLE piconets with the ratio of connection interval to connection event length as the main parameters. The analysis result can be used to set connection event related parameters for a desired packet collision probability according to the number of users having BLE devices in a given space.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9B
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• pp.581-590
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• 2005

The IEEE 802.17 Resilient Packet Ring Working Group develops standards to support the development and deployment of Resilient Packet Ring networks in Local, Metropolitan, and Wide Area Networks for resilient and efficient transfer of data Packets at rates scalable to many gigabits Per second. It was known that the fairness algorithm of the IEEE 802.17 Resilient Packet Ring suffers from throughput degradation under an unbalanced overload. This Paper proposes a congestion release advertisement method to improve this throughput degradation and discusses its performance. Under the proposed method, a congested node decides whether its congestion is released or not. If released, it advertises the congestion release to upstream nodes, and then upstream nodes transmit their traffic without uy regulation. The proposed method is compatible with the legacy fairness algorithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.53-58
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• 2013

A Fat-Tree topology has multiple paths between any pair of hosts. The delay for the multiple paths with an equal number of hops depends mainly on the queuing delay. However, most of the existing load-balancing schemes do not sufficiently exploit the characteristics of Fat-Tree. In most schemes load-balancing is performed at a flow level. Packet-level load-balancing schemes usually require the availability of special transport layer protocols to address packet reordering. In this paper, we propose a new packet-level load-balancing scheme which can enhance network utilization while minimizing packet reordering in Fat-Trees. Simulation results show that the proposed scheme provides as high TCP throughput as a randomized flow-level Valiant load balancing scheme for a best case.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1646-1652
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• 2010

The communication in wireless sensor network is divided into several layers, because of each of them do their role, the wireless communication is possible, the MAC (Medium Access Control) layer of the one of sensor network communications layer is used to the data errors, control flow, and manage resources. Using MAC Protocol, it ensures the communication between sensor node. In this paper, highlighted the energy efficiency of the S-MAC, T-MAC protocol it emphasized the efficiency of energy by lessening the woken time of all nods effectively, transmitting and receiving the control packet on only necessary nods through use of a method that RTS packet is added to SYNC packet and making other nods sleep. On sending SYNC+RTS packet and receiving the packet, nod noticed that it wasn't necessary to be awaked on this period, would be in Sleep mode, demonstrated mathematically that energy is more effective than existing protocol, and simulated with MATLAB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1777-1784
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• 1998

The packet error rates of an optical packet switching node with an optical address processor using an EDFA in order to detect M-ary correlation pulses at a fiber-optical delay line matched filter output have been evaluated. Effects of A PIN diode NEP, the gain and noise figure of the EDFA, and the bandwidth of an optical filter on the packet error rate of the switching node have been compared. There is negligible error rate change depending upon the variation of the PIN diode NEP and the EDFA gain. If the bandwidth of the optical filter is below 10 times of the data rate, there is no appreciable effect on the error rate. If the noise figure of the EDFA increases, however, the power penalty increases as much as the noise figure increment at all the bit rates and for address code sets considered in this work.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.689-694
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• 2014

DDoS attacks on MANET makes disable any node which support network function, cause critical results as a stopping of entire network service or separation to some parts. Packet aggregation, which gather some pieces of short length into a certain length of data, improves transmission performances on MANETs. In this paper, some effects on transmission performance of packet aggregation transmission be caused by DDoS Attacks are measured and analyzed in point of end-to-end level. MANET simulator, based on NS-2, is used for measurement end-to-end performances. MOS, connection rate, delay and packet loss rate is used as performance parameters. VoIP traffic is used for object service measurement. Finally, it is suggested that number of packet aggregation is more then 4 for keeping the transmission quality over MANETs under DDoS attacks.