• The KIPS Transactions:PartB
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• v.15B no.6
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• pp.585-594
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• 2008

The issues that we should consider in the process of providing mobile web service using a mobile device are seamless service and QoS-guaranteed service. HMIPv6 has MAP because of improving packet loss and transmission delay due to disconnection. However, a load is concentrated on HMIPv6 because of receiving and delivering packet for MN. Owing to this, real time data fails to be processed quickly, and also adaptive mobile service is required for QoS guaranteed service. However, this method demands the response time cost of contents service owing to the hardware differences of various devices. Therefore, we improve the process performance of real time data by applying a queue in MAP for seamless service in this paper. For decreasing response time cost, we propose mobile web service method which has reusable cache of contents using the elements of contents. The result of a numerical formula and simulation shows that our proposed method is superior under various system conditions.

• Journal of KIISE:Information Networking
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• v.33 no.6
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• pp.451-460
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• 2006

In HMIPv6, the nested mobile network because of the mobility of node and router can be constituted. Many subnets exist and many mobile router(MR)s and mobile node(MN)s activate in the nested mobile network. If the nested depth is deeper, the number of mobile router that packet goes through, increases and data transmission delay owing to this might be larger. This paper proposes EPA algorithm which finds out the path from Mobility Anchor Point(MAP) to a destination mobile node using the binding cache information of MAP and processes the path information by adding it to packet header. If we apply EAP algorithm, the quantity of unnecessary packet within MAP domain can be decreased. Also, the transmission delay can be decreased in a intermediate mobile router because it supports packet re-transmission just by simple packet substitution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1312-1318
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• 2020

In this paper, we propose a video transmission scheme for exclusive OR based video streaming (XC) that can improve the efficiency of video streaming by using receivers' caches and coding of video data. Contrary to conventional streaming schemes such as multicast where video contents can be transmitted on single channel only when two clients request the same video, the proposed streaming scheme can transmit video contents on single channel conditionally according to the status of the clients' caches even though two clients request different video contents. We analyze the performance of the proposed transmission for XC in terms of the streaming efficiency through extensive computer simulations and compare it with a conventional scheme. Simulation results show that the proposed scheme can enhance the streaming efficiency by 21%, compared with the conventional scheme.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.105-111
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• 2010

SWF(Shock Wave Flash) file is a format file for vector graphics produced by Adobe. It is widely used for a variety of contents such as advertising at websites, widgets, games, education, and videos and it contains various types of data such as sound sources, script, API and images. Many SWF files contain URL information on action script for communication in the network and they can be used as important research data as well as PC users' Web Browser history in terms of forensic investigation. And a decompiler for analyzing SWF files exists by which SWF files can be analysed and URL information can be verified. However, it takes a long time to verify the URL information on action scripts of multiple SWF files by the decompiler. In this paper, analysis of URL information on action scripts and extraction of URL information from multiple SWF files by designing analysis tools for URL information in SWF files is studied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.497-500
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• 2018

As the fourth industrial revolution began to take off in earnest, the quality and quantity of data shared among devices began to increase exponentially over the network. In addition, the category of devices where people are exposed to such data has become diversified into desktops, mobile phones, smart phones, smart pads, and smart watches. As a result, the medium that contacts the data has begun to change, and the place where modern society has the most data is smart device. However, smart devices still leave much to be desired in terms of network speed and hardware specifications to handle large amounts of data at one time. Therefore, in this paper, we analyze the use of Service Worker, IndexedDB, and LocalStroage, which can retrieve a large amount of web contents more efficiently from mobile devices, and suggest ways to improve it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8C
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• pp.670-679
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• 2012

The recent dissemination of cloud computing makes the amount of data storage to be increased and the cost of storing the data grow rapidly. Accordingly, data and service requests from users also increases the load on the cloud storage. There have been many works that tries to provide low-cost and high-performance schemes on distributed file systems. However, most of them have some weaknesses on performing parallel and random data accesses as well as data accesses of frequent small workloads. Recently, improving the performance of distributed file system based on caching technology is getting much attention. In this paper, we propose a CHPC(Cloud storage High-Performance Caching) framework, providing parallel caching, distributed caching, and proxy caching in distributed file systems. This study compares the proposed framework with existing cloud systems in regard to the reduction of the server's disk I/O, prevention of the server-side bottleneck, deduplication of the page caches in each client, and improvement of overall IOPS. As a results, we show some optimization possibilities on the cloud storage systems based on some evaluations and comparisons with other conventional methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8B
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• pp.730-737
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• 2003

In this paper, we present an efficient authentication proxy for IEEE 802.1x systems based on the port-based access control mechanism. An IEEE 802.1x system consists of PC supplicants, a bridge with authentication client functions, and an authentication server. For the network security and user authentication purposes, a supplicant who wants to access Internet should be authorized to access the bridge port using the Extended Authentication Protocol (EAP) over LAN. The frame of EAP over LAN is then relayed to the authentication server by the bridge. After several transactions between the supplicant and the server via the bridge, the supplicant may be either authorized or not. Noting that the transactions between the relaying bridge and the server will be increased as the number of supplicants grows in public networks, we propose a scheme for reducing the transactions by employing an authentication proxy function at the bridge. The proxy is allowed to cache the supplicant's user ID and password during his first transaction with the server. For the next authentication procedure of the same supplicant, the proxy function of the bridge handles the authentication transactions using its cache on behalf of the authentication server. Since the main authentication server handles only the first authentication transaction of each supplicant, the processing load of the server can be reduced. Also, the authentication transaction delay experienced by a supplicant can be decreased compared with the conventional 802.1x system.

• The KIPS Transactions:PartA
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• v.16A no.2
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• pp.113-124
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• 2009

With increasing multicore system, much effort has been put on the performance improvement of its application. Because multicore system has multiple processing devices in one system, its processing power increases compared to the single core system. However in many cases the advantages of multicore can not be exploited fully because the existing software and hardware were designed to be suitable for single core. When the existing software runs on multicore, its performance improvement is limited by the bottleneck of sharing resources and the inefficient use of cache memory on multicore. Therefore, according as the number of core increases, it doesn't show performance improvement and shows performance drop in the worst case. In this paper we propose a method of performance improvement of multicore system by applying Flow-Level Parallelism to the existing TCP/IP network application and operating system. The proposed method sets up the execution environment so that each core unit operates independently as much as possible in network application, TCP/IP stack on operating system, device driver, and network interface. Moreover it distributes network traffics to each core unit through L2 switch. The proposed method allows to minimize the sharing of application data, data structure, socket, device driver, and network interface between each core. Also it allows to minimize the competition among cores to take resources and increase the hit ratio of cache. We implemented the proposed methods with 8 core system and performed experiment. Experimental results show that network access speed and bandwidth increase linearly according to the number of core.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.5
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• pp.293-299
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• 2007

Intelligent pipeline inspection gauges (PIGs) are inspection vehicles that move along within a (gas or oil) pipeline and acquire signals (also called sensor data) from their surrounding rings of sensors. By analyzing the signals captured in intelligent PIGs, we can detect pipeline defects, such as holes and curvatures and other potential causes of gas explosions. There are two major data access patterns apparent when an analyzer accesses the pipeline signal data. The first is a sequential pattern where an analyst reads the sensor data one time only in a sequential fashion. The second is the repetitive pattern where an analyzer repeatedly reads the signal data within a fixed range; this is the dominant pattern in analyzing the signal data. The existing PIG software reads signal data directly from the server at every user#s request, requiring network transfer and disk access cost. It works well only for the sequential pattern, but not for the more dominant repetitive pattern. This problem becomes very serious in a client/server environment where several analysts analyze the signal data concurrently. To tackle this problem, we devise a fast in-memory cache manager, called T-Cache, by considering pipeline sensor data as multiple time-series data and by efficiently caching the time-series data at T-Cache. To the best of the authors# knowledge, this is the first research on caching pipeline signals on the client-side. We propose a new concept of the signal cache line as a caching unit, which is a set of time-series signal data for a fixed distance. We also provide the various data structures including smart cursors and algorithms used in T-Cache. Experimental results show that T-Cache performs much better for the repetitive pattern in terms of disk I/Os and the elapsed time. Even with the sequential pattern, T-Cache shows almost the same performance as a system that does not use any caching, indicating the caching overhead in T-Cache is negligible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2B
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• pp.129-137
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• 2003

Multimedia streams, like MPEG continuously retrieve multimedia data because of their incessant playback. While these streams need an efficient support of kernel, the current buffer cache mechanism of Linux kernel such as Unix operating system was designed apt for small files, which is aperiodically requested as well as time uncritical. But, in case of continuous media, the CPU must enormously copy memory from kernel address space to user address space. This must lead to a large CPU overhead. This overhead both degrades system throughput and cannot guarantee QOS. In this paper, we have designed and implemented two memory copy reduction schemes in Linux kernel, direct I/O and one copy. The direct I/O skips the buffer cache layer of Linux kernel and results in dramatic reduction of CPU memory copy overhead. And, the one copy provides a fast disk-to-network data path without copying to user address space. The experimental results show considerable reduction of CPU overhead and throughput improvements.