• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.339-346
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• 2013

As the need for security of SCADA systems is increasing, significant progress has been made in research on security of control protocol. However, very few security solutions were adapted to legacy SCADA system. The reasons for non-adoption are latency, cost and key management problem. We propose a low latency, economic security Solution to solve these issues. The proposed solution performs security function in data link layer and has minimum overhead to minimize latency. Furthermore, we try to solve the key management problem by providing systematic security keys and key distribution method.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.163-176
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• 2013

Cloud-based streaming game service has numerous merits, but it may suffer from presentation latency in a thin-client. It is an important issue especially for game service which needs instantaneous response to user inputs. This research proposes the methods for reducing the presentation latency between the server unit and the thin-client unit. The approaches proposed to be employed with server unit include the source/sync video format equalization, encoding format configuration according to the media type, and the S/W implementation for transmitting clock periodically. The methods for the thin-client unit include the decreasing the number of instructions, use of light encryption algorithm, and improvement on H/W decoding. The proposed schemes are tested with a commercialized streaming service platform, which reveals the reduction of presentation latency as large as a few hundred milliseconds and reaches the acceptable level (about 100 milliseconds).

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.11
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• pp.581-591
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• 2001

We consider some problems of remote file accesses of multiple clients in mobile computing environments. In this environment, user mobility affects file access latency. Mobile hosts have severe resource constraints in terms of limited size of non-volatile storage. Thus, the burden of computation and communication load raise file access latency. In this paper, we propose a scheme for reducing the file access latency through the file migration. The objective is to minimize of file accesses for all mobile hosts which delivering the file to clients as quickly as possible. We develope an on-demand scheme which determines when the file server should migrate files to another server, or when it should transfer files to mobile hosts. Using simulation, we examine the effects which parameters such as file access frequency, file size, mobility rate have on file system access latency. Through simulation results, we show that our proposed migration scheme is effective in reducing the access latency on the requested file of a mobile host with high access rate and low mobility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.473-478
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• 2008

WAVE is a short-to-medium range communication standard that supports both public safety and private operations in roadside-to-vehicle and vehicle-to-vehicle communication environments. The core technology of physical layer in WAVE is orthogonal frequency division multiplexing (OFDM), which is sensitive to timing synchronization error. Besides, minimizing the latency in communication link is an essential characteristic of WAVE system. In this paper, a robust, low-complexity and small-latency timing synchronization algorithm suitable for WAVE system and its efficient hardware architecture are proposed. The comparison between proposed algorithm and other algorithms in terms of computational complexity and latency has shown the advantage of the proposed algorithm. The proposed architecture does not require RAM (Random Access Memory) which can affect the pipe lining ability and high speed operation of the hardware implementation. Synchronization error rate (SER) evaluation using both Matlab and FPGA implementation shows that the proposed algorithm exhibits a good performance over the existing algorithms.

• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.113-120
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• 2006

A node of mobile IPv6 moving foreign networks needs authentication process to support right services against from security threat. AAA is a trust infrastructure that authenticates, authorizes, and accounts nodes receiving a network service. And Mobile IPv6 Working Group recommends use of AAA infrastructure to authenticate mobile nodes. Event though AAA infrastructure provides strong authentication functions, it should exchange a lot of messages to authenticate mobile nodes every movement. The exchange of lots of messages causes latency and it is interfered with realization of real-time communication. This paper proposes an authentication method of improved speed using hash value of mobile node to reduce authentication latency. Directly after movement, a mobile node applying a Proposed method uses extended existing security authentication for a while and deletes the establishment latency of new security authentication. Performance evaluation of a proposed method verifies the efficiency through the analysis of cost comparison with other methods. The conclusion of performance evaluation is that the proposed method gets more 25% performance improvement than a general method when a mobile node moves another subnet.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.460-475
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• 2016

The existing Proxy Mobile IPv6 suffers from a long handover latency which in turn causes significant packet loss that is unacceptable for seamless realtime services such as multimedia streaming. This paper proposes an OpenFlow-enabled proxy mobile IPv6 (OF-PMIPv6) in which the control of access gateways is centralized at an OpenFlow controller of a foreign network. The proposed OF-PMIPv6 separates the control path from the data path by performing the mobility control at the controller, whereas the data path remains direct between a mobile access gateway and a local mobility anchor in an IP tunnel form. A group of simple OpenFlow-enabled access gateways performs link-layer control and monitoring activities to support a comprehensive mobility of mobile nodes, and communicates with the controller through the standard OpenFlow protocol. The controller performs network-layer mobility control on behalf of mobile access gateways and communicates with the local mobility anchor in the Proxy Mobile IPv6 domain. Benefiting from the centralized view and information, the controller caches the authentication and configuration information and reuses it to significantly reduce the handover latency. An analytical analysis of the proposed OF-PMIPv6 reactive and proactive handover schemes shows 43% and 121% reduction in the handover latency, respectively, for highly utilized network. The results gathered from the OF-PMIPv6 testbed suggest similar performance improvements.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.12
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• pp.655-664
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• 2002

In many data-parallel applications massive parallelism can be easily extracted through data distribution. But it often causes very long communication latency. This paper shows that task parallelism, which is extracted from data-parallel programs, can be exploited to hide such communication latency Unlike the most previous researches over exploitation of task parallelism which has not been considered together with data parallelism, this paper describes exploitation of task parallelism in the context of data parallelism. PCFG(Parallel Control Flow Graph) is proposed to represent a multithreaded program consisting of a few task threads each of which can include a few data-parallel loops. It is also described how a PCFG is constructed from a source data-parallel program through HDG(Hierarchical Dependence Graph) and how the multithreaded program can be constructed from the PCFG.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.253-256
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• 2004

A new multicast scheme for mobile nodes is proposed to support real-time communication in a more efficient way. In the proposed multicast scheme, the Explicit multicast (Xcast) is integrated with the Session Initiation Protocol (SIP). The proposed scheme reduces unnecessary network traffic and achieves low latency of packets in the network.

• Journal of information and communication convergence engineering
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• v.8 no.2
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• pp.234-237
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• 2010

P300 component of the event-related potential(ERP) has been studied for theoretical, empirical, and clinical applications. Nowadays the 1-, 2-, and 3-stimulus oddball paradigms are used for eliciting P300 component of EEG in the auditory stimulus experiments. In this paper, we used a method to add one more stimulus to the 3-stimulus auditory paradigm. The adding stimulus has not the same volume but the same tone of the target stimulus. The 4-stimulus oddball paradigm to use two targets is used to elicit the P300 event-related potentials. In 4-stimulus oddball paradigm, an infrequent non-target (p=0.10) is presented in addition to two infrequent targets (p=0.10) and a frequent standard (p=0.70). Two target stimuli elicited a P300 component with a parietal maximum distribution. The amplitude of the P300 in target 2 was larger than that in target 1 and the latency of the P300 in target 2 was longer than that in target 1. The P300 component due to target 2 stimuli was larger than that due to target 1 stimuli. The experimental results approve that the 4-stimulus oddball paradigm can elicit P300 component clearly. The results are compared with the results of the traditional oddball paradigm.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.678-685
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• 2016

The standard high-availability seamless redundancy (HSR) protocol utilizes duplicated frame copies of each sent frame for zero fail over time. This means that even in cases of a node or link failure, the destination node will receive at least one copy of the sent frame, resulting in no network downtime. However, the standard HSR is mostly based on the electrical signal connection inside the node, which leads to the production of considerable latency at each node due to frame processing. Therefore, in a large scale HSR ring network, the accumulated latencies become significant and can often restrict the mission-critical real-time application of HSR. In this paper, we present a novel design for optical HSR (OHSR) that uses beam splitting/combining techniques. The proposed OHSR passes the frames directly to adjacent nodes without frame processing at each node, thereby theoretically generating no latency in any node. Various simulations for network samples, made to validate the OHSR design and its performance, show that the OHSR outperforms the standard HSR.