• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.70.3-70
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• 2001

In this paper, we suggest a kernel level multi thread web accelerator (called the SCALA-AX), which significantly improves the performance of the web soerver. In comparison with a conventional proxy web cache that is generally called a caching server and a simple content-copy based system, the primary functions and goals of SCALA-AX are designed to maximize the content services of a front end web server with high performance. Specifically, the SCALA-AX runs on the kernel level of a web sorrel, based on the newest caching techniques. Moreover, the SCALA-AX supports the http 1.1 protocol and allows the dynamic pages as well as static pages to be processed.

• Journal of KIISE:Information Networking
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• v.27 no.3
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• pp.301-314
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• 2000

As the number of World Wide Web (Web) users grows, Web traffic continues to increase at an exponential rate. Currently, Web traffic is one of the major components of Internet traffic. Also, high bandwodth usage due to Web traffic is observed during peak periods while leaving bandwidth usage idle during off-peak periods. One of the solutions to reduce Web traffic and speed up Web access is through the use of Web caching. Unfortunately, Web caching has limitations for reducing network bandwidth usage during peak periods. In this paper, we focus our attention on the use of a prefetching algorithm for reducing bandwidth during peak periods by using off-peak period bandwidth. We propose a statistical, batch, proxy-side prefetching scheme that improves cache hit rate while only requiring a small amount of storage. Web objects that were accessed many times in previous 24 hours but would be expired in the next 24 hours, are selected and prefetched in our scheme. We present simulation results based on Web proxy and show that this prefetching algorithm can reduce peak time bandwidth using off-peak bandwidth.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.379-386
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• 2004

The WAP 2.0 system is a newly proposed wireless communication system by the WAP Forum for interoperability across Internet environment and the system takes charge of communication between WAP terminals and existing origin Web servers. The purpose of this paper is 1) to construct a WAP 2.0 proxy proposed by the WAP Forum and 2) to improve the WAP Proxy in order to increase communication efficiency between wired and wireless communication objects. The Improved WAP proxy constructed in this study provides links between wired and wireless communication environments using the split-TCP concept. However, unlike the split-TCP connection, The improved WAP proxy maintains TCP's end-to-end semantics and reduces overhead by avoiding operations as much as possible on the upper protocol layer. In addition, The improved WAP proxy supports SACK(Selective Acknowledgement ) option and Timestamp option for speedy re-transmission which leads to reduction of performance degradation. After constructing the improved WAP proxy under Linux environment, experiments have been taken. The experimental results show that, compared with the experiments when a WAP proxy proposed by the WAP Forum is used, both data transmission delay time and data transmission size decrease to show that communication efficiency is increased. In particular, as packet missing ratio Increases, data transmission size decreases, which demonstrates that the improved WAP proxy is very effective for performance improvement in wireless communication environment.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.463-476
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• 2001

To support the mobility, mobile computers are generally equipped with lower capability than desktop PCs or workstations in terms of the size of a display, the processing power of CPU and so on. This may give a rise to limitation in mobile computers of supporting multimedia services such as World Wide Web which users would otherwise fully enjoy in desktop PCs. Approaches to reducing the limitations are distillating original multimedia data or converting them to text. Conventional proxy servers for mobile computer simply send distillated image files with the fixed size regardless of the display size of a target mobile computer. Since the cached data is kept separately for each user, they cannot be shared among users with the same display configuration and thus the proxy server could be overloaded. In this paper, we first classify various mobile computers based on their display capability in terms of display sizes and colors. We propose an enhanced proxy server called Class-based proxy that provides a mobile computer with distillated image files in proportion to its class display capacity. The proposed proxy server allows a mobile computer user to have a homepage view similar to that in PC or Workstation. Mobile computers with the same class share the cached image files, which are distillated appropriately for that class. This helps the proxy server to get higher cache hit ratio with improved efficiency and scalability.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.725-730
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• 2009

Recently, there has been increasing interest to web access through mobile host due to the explosion of internet mobile terminal such as smart phone. However, small displays of mobile hosts make it difficult to browse the full content of a web page at a time. In order to overcome these limitation, we have designed and implemented Web-based text summarization system. The proposed system can summarize the text for the Web page in which abundant text exist in a page. This can reduce the amount of data transmission and minimize the unnecessary data output during browsing at mobile host. Through implementation, we have confirmed the functions of the proposed system.

• Journal of Communications and Networks
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• v.12 no.3
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• pp.201-208
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• 2010

We propose a new notion of metered signatures. Metered signature is an extension of k-times signatures in which a signer can generate only k signatures. However, the restriction of metered signatures can be more elaborate: It can be used k-times every day or to preserve the order of signed messages in some applications. Any violation of this regulation reveals a secret key or the signature on a predetermined message. The applications includes proxy signatures, limited free downloads, and the rating web site. We give two instances of metered signatures: One is based on the computational Diffie-Hellman problem (CDHP) using a bilinear map and the other is based on the RSA problem. In both schemes, the signature and certificate size and the verification cost are constant with respect to k. Further, we show that the proposed metered signatures admit batch verification of many signatures almost at one verification cost with small security loss.

• Journal of Information Processing Systems
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• v.15 no.1
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• pp.100-115
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• 2019

Malicious code distribution on the Internet is one of the most critical Internet-based threats and distribution technology has evolved to bypass detection systems. As a new defense against the detection bypass technology of malicious attackers, this study proposes the automated tracing of malicious websites in a malware distribution network (MDN). The proposed technology extracts automated links and classifies websites into malicious and normal websites based on link structure. Even if attackers use a new distribution technology, website classification is possible as long as the connections are established through automated links. The use of a real web-browser and proxy server enables an adequate response to attackers' perception of analysis environments and evasion technology and prevents analysis environments from being infected by malicious code. The validity and accuracy of the proposed method for classification are verified using 20,000 links, 10,000 each from normal and malicious websites.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.64-72
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• 2006

The long propagation delay over satellite internet causes degradation of TCP performance in slow start phase. Especially, web traffic performance is greatly reduced by low throughput in slow start phase. To improve web traffic performance, we propose the Dynamic ACK Generation Scheme which generates ACKs and considers sender RTO in PEP (Performance Enhancing Proxy). The Normal ACK generation mechanism improves TCP throughput, and also decreases sender RTO. if PEP stops generating ACKs, TCP performance will be reduced by frequent RTO expiration. To solve this problem, our scheme adjusts RTO using ACK generation interval. And it supports retransmission mechanism for loss recovery in PEP. The results of the performance analysis provide a good evidence to demonstrate the efficiency of our mechanisms over satellite internet.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.829-830
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• 2006

A distributed web caching system can transmit information to a user quickly and stably, avoiding a congested internet network by storing and later supplying requested content to a cache that is distributed and shared like a proxy server. This paper proposes a client-based distributed web caching system that assigns an object and controls the load using a user's direct connection to shared caches, without the aid of additional domain name system (DNS) requests. The proposed system simplifies information transmission by reducing both DNS queries and delay time.

• The KIPS Transactions:PartA
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• v.9A no.3
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• pp.327-332
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• 2002

Conventional proxy web cache, which is generally used to caching server, is a content-copy based system. This method focuses on speeding up the phase delivery not improving the webserver performance. However, if immense clients attempt to connect the webserver simultaneously, the proxy web cache cannot achieve the desired result. In this paper, we propose the web accelerator called the SCALA-AX, whitch improves web server performance by accelerating the delivery contents. The SCALA-AX is built in the Linux-based kernel as a kernel modulo and works in combination with the conventional webserver program. The SCALA-AX speeds up the processing rate of the webserver, because it processes the requests using the kernel thread. The SCALA-AX also applies the well-developed cache algorithm to the processing, and thus it obtains the advantage of the caching server without installing additional hardware. A banchmarking test demonstrates that the SCALA-AX improves webserver performance by up to 500％ for content delivery.