• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.68-75
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• 2011

The performance of peripheral devices is improving rapidly to meet the needs of users for multimedia data. Therefore, the peripheral interface with wide bandwidth and high transmission rate becomes necessary to handle large amounts of data in real time for multiple high-performance devices. PCI Express is a fast serial interface with the use of packets that are compatible with previous PCI and PCI-X. In this paper, we design and verify general peripheral interface using serial link. It includes two kinds of traffic class (TC) labels which are mapped to virtual channels (VC). The design adopts TC/VC mapping and the scheme of arbitration by priority. The design uses a packet which can be transmitted through up to four transmission lanes. The design of general peripheral interface is described in Verilog HDL and verified using ModelSim. For FPGA verification, Xilinx ISE and SPARTAN XC3S400 are used.We used Synopsys Design Compiler as a synthesis tool and the used library was MagnaChip 0.35um technology.

• Journal of Advanced Navigation Technology
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• v.18 no.5
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• pp.461-467
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• 2014

Active queue management (AQM) algorithms run on routers and detect incipient congestion by typically monitoring the instantaneous or average queue size. When the average queue size exceeds a certain threshold, AQM algorithms infer congestion on the link and notify the end systems to back off by proactively dropping some of the packets arriving at a router or marking the packets to reduce transmission rate at the sender. Among the existing AQM algorithms, random early detection (RED) is well known as the representative queue-based management scheme by randomizing packet dropping. To reduce the number of timeouts in TCP and queuing delay, maintain high link utilization, and remove bursty traffic biases, the RED considers an average queue size as a degree of congestions. However, RED do not well in the specified networks conditions due to the fixed parameters($P_{max}$ and $TH_{min}$) of RED. This paper addresses a extended RED to be adapted in various networks conditions. By sensing network state, $P_{max}$ and $TH_{min}$ can be automatically changed to proper value and then RED do well in various networks conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.800-806
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• 2015

WAVE(Wireless Access in Vehicular Environments) system is wireless communication technology that vehicle sends and receives packets between vehicles or between vehicles and infrastructure in a high-speed mobile environment. In this study, we have designed and implemented a CRL(Certificate Revocation List) download protocol that is used to verify certificate revocation status of the other party when the vehicles communicate with WAVE system. This protocol operates over UDP. And to support security features, also, ECDSA(Elliptic Curve Digital Signature Algorithm) is used for mutual authentication and ECIES(Elliptic Curve Integrated Encryption Scheme) is used to ensure the confidentiality. Moreover, this protocol ensures the integrity of data by adding MAC(Message Authentication Code) to the end of packet and support the error and flow control mechanisms.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.281-290
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• 2010

In geographic forwarding algorithms, traditional route maintenance requires mobile nodes periodically exchange beacon messages with their neighbors. In beacon message based forwarding scheme, a longer interval reduces the number of beacons needed, but may result in significant location errors. Conversely, a shorter interval guarantees more accurate location information, but induces control overheads.Therefore, the fixed or dynamic interval scheme based forwarding schemes cannot adapt well to different mobility environments. Also, existing schemes result in the uncertainty of neighbor node's position in the forwarding table of mobile node. Therefore, this paper presents a self-adaptive location checking mechanism based proactive geo-routing algorithm for beacon-based geographic routing. Simulation results show that the proposed routing algorithm not only significantly increases the relay transmission rate but also guarantees the high end-to-end packet delivery in low and high mobility environments.

• The Journal of the Korea Contents Association
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• v.10 no.9
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• pp.79-87
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• 2010

This paper proposes a L3 handover method to minimize packet loss for supporting service continuity to IMS Terminal which has a single WLAN interface. The existing IMS based handover solution is able to support handover between different access networks in case that a terminal has multiple interfaces. That is, WLAN terminals need multiple interfaces to connect with one or more access networks. This proposed method configures IP address for the terminal in target WLAN previously by using Candidate Access Router Discovery(CARD) mechanism. Also, in the proposed method, service continuity server performs L3 connection establishment in target WLAN and registration to IMS server instead of the terminal. And then session control mechanism based on SIP is performed to support service continuity. We analyzed handover latency and signaling cost in the proposed method and existing method to show the improved performance by the proposed method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.3
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• pp.259-269
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• 2018

Multipath TCP (MPTCP) can be expected to provide improved network performance because it transmits data through multiple paths. However, Bufferbloat, which unexpectedly occurs in the transmission path, degrades not only the performance of the corresponding path but also the performance of other paths, so that the performance is worse than that of a single TCP. In this paper, we propose the transmission status monitoring method at the sender's MPTCP level and also HoL packets retransmission algorithm in order to solve the Bufferbloat problem. The proposed algorithm enables Bufferbloat detection by the sender side independently, and it can resolve the HoL blocking problem by identifying the HoL packet in the proposed transmission status monitoring buffer and retransmitting it to the normal path. Simulation results based on NS-3 show that the proposed algorithm achieves the improved throughput performance up to 22.8% compared to the existing MPTCP, and the average number of queued packets in the sender and receiver's buffers is decreased to 44.3% and 9.2%, respectively.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.93-101
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• 2002

This paper presents the Internet audio broadcasting technology based on the streaming technology. In this paper, we choose the MPEG-2 AAC for multimedia data, and for the streaming of this data we use RTP/RTCP protocol. We use RTSP protocol for the control of streaming data and TCP/IP for the exchange of information between server and client. By using all of these protocols and MPEBG-2 AAC, we explain the implementation method for the unicast/multicast streaming server/client system. Our system was tested by ETRI intranet, which is connected by 2000 researchers. Experimental result show that our system can be process the packet loss and jitter by retransmission and variable length buffer. Multicast streaming server can be used for the audio broadcasting service inside the company, unicast streaming server can be used for the AOD (Audio On Demand) service.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.128-131
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• 2006

There are two traditional scheduling methods known as PQ and WRR in the DiffServ network, however, these two scheduling methods have some drawbacks. In this paper, we propose an algorithm that can be adopted in WRR scheduler with making up for weak points of PQ and WRR. The proposed algorithm produces the control discipline by the fuzzy theory to dynamically assigns the weight of WRR scheduler with checking the Queue status of each class. To evaluate the performance of the proposed algorithm, We accomplished a computer simulation using NS-2. In result, the proposed algorithm enhances the packet discard rate at the EF class than WRR scheduling method and the AF4 class than PQ scheduling method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2387-2394
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• 2016

It is important to select the most appropriate channel for efficient transmission of massive data in wireless sensor network. In the fixed channel method for wireless sensor node, shortage of frequency may be a major constraint to support a variety of environments. In this paper, the method that seeks common channels between two nodes without common control channels in the existing wireless cognitive radio network is introduced in order to use efficiently the channel of wireless sensor network. The problem of existing method shows the severe degradation of performance that is caused by interference of linkage between selected channels, so that the sequential algorithm is suggested to improve the performance. From the results of computer simulation, the suggested method shows that the link can be set 50% faster than the other methods as the number of links increases because the beacon packet waiting time caused by the interference decreases remarkably.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.72-84
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• 2005

Optical burst switching networks usually employ one-way reservation by sending a burst control packet with a specific offset time, before transmitting each data burst Same. Due to such a Property, burst-contentions occur when multiple bursts contend for the same wavelength in the same output link simultaneously in a node, leading to burst losses, eventually degrading the quality of service. Therefore, in this paper, we propose a dynamic routing algorithm using minimum local state information in order to decrease burst-contentions. In this proposed scheme, if burst loss rate exceeds a threshold value at a certain node, a new alternative routing path is chosen according to burst priority and location of burst generation, which enables the contending bursts to detour around the congested link. Moreover, for reducing the effect of sending bursts on the primary path due to the alternative path, we also apply a minimum path-cost based routing on link-cost concept. Our simulation results show that proposed scheme improves the network performance in terms of burst loss probability and throughput by comparing with conventional one.