• Journal of the Korea Society for Simulation
• /
• v.9 no.2
• /
• pp.1-14
• /
• 2000

Recently, as construction of information infra including high-speed communication networks remarkably expands, more various information services have been provided. Thus the number of internet users rapidly increases, and it results in heavy load on Web server and higher traffics on networks. The phenomena cause longer response time that means worse quality of service. To solve such problems, much effort has been attempted to loosen bottleneck on Web server, reduce traffic on networks and shorten response times by caching informations being accessed more frequently at the proxy server that is located near to clients. And it is also possible to improve internet performance further by allowing clients to share informations stored in proxy caches. In this paper, we perform simulations of hierarchical proxy caches with the 3-level 4-ary tree structure by using real web traces, and analyze cache hit ratio for various cache replacement policies and cache sizes when the delayed-store scheme is applied. According to simulation results, the delayed-store scheme increases the remote cache hit ratio, that improves quality of service by shortening the service response time.

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.6
• /
• pp.1177-1190
• /
• 2009

In this paper, we propose a fuzzy proxy cache scheme for caching web documents in mobile base stations. In this scheme, a mobile cache model is used to facilitate data caching and data replication. Using the proposed cache scheme, the individual proxy in the base station makes cache decisions based solely on its local knowledge of the global cache state so that the entire wireless proxy cache system can be effectively managed without centralized control. To improve the performance of proxy caching, the proposed cache scheme predicts the direction of movement of mobile hosts, and uses various cache methods for neighboring proxy servers according to the fuzzy-logic-based control rules based on the membership degree of the mobile host. The performance of our cache scheme is evaluated analytically in terms of average response delay and average energy cost, and is compared with that of other mobile cache schemes.

• Journal of Industrial Convergence
• /
• v.20 no.11
• /
• pp.49-55
• /
• 2022

This study is a secondary data analysis study to confirm the difference in responses to psychological and supportive factors of severely disabled according to proxy responses using the National Survey of the Disabled 2020. 738,169 people with severe disabilities who were 19 years of age or older, whose main disability was not an intellectual disability, were analyzed. χ²-test and t-test were performed using IBM SPSS Statistics 26.0. As a result of the study, the proxy response was more negative in sadness or hopelessness (χ²=952.20, p<.001), suicidal ideation (χ²=369.45, p<.001), and subjective health status (t=30.61, p<.001). And the proxy respondent answered that they need more support from others for daily life (t=209.43, p<.001) and have many difficulties in communication when using medical services (t=41.74, p<.001). When using a proxy response, the researcher should clearly state the point of view that the proxy respondent should take, and interpret the results considering that proxy response may be affected by various factors.

• Convergence Security Journal
• /
• v.12 no.6
• /
• pp.101-106
• /
• 2012

As the existing strategy of preventing DDoS(Distributed Denial of Service) attacks has limitations, this study is intended to suggest the more effective method of preventing DDoS attacks which reduces attack power and distributes attack targets. Currently, DDoS attacks have a wide range of targets such as individuals, businesses, labs, universities, major portal sites and financial institutions. In addition, types of attacks change from exhausting layer 3, network band to primarily targeting layer 7. In response to DDoS attacks, this study suggests how to distribute and decrease DDoS threats effectively and efficiently using Proxy Server Group and Dynamic DNS.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.10b
• /
• pp.1407-1410
• /
• 2001

무선 어플리케이션 서비스 시스템 구축시 가장 중요한 역할을 담당하는 장비는 WAP Proxy 서버이다. 캐시 기능이 추가된 WAP Proxy 서버는 캐시 서버와 Gateway가 연동하여 해당 URL의 Request에 대한 응답 시간(response time)을 줄이기 위해 구현된 시스템이다. 본 논문은 캐시 기능을 이용한 WAP Proxy 서버의 성능을 측정하기 위해, 별도로 구현한 성능 측정 시스템을 이용, 그 성능은 비교 분석했다. 성능 측정 시스템은 C로 구현했으며, 실시간으로 그 결과를 확인 할 수 있다.

• Journal of Ubiquitous Convergence Technology
• /
• v.2 no.1
• /
• pp.1-11
• /
• 2008

An effective solution to the problems caused by the explosive growth of World Wide Web is a web caching that employing an additional server, called proxy cache, between the clients and main server for caching the popular web objects near the clients. However, a single proxy cache can easily become the bottleneck. Deploying groups of cooperative caches provides scalability and robustness by eliminating the limitations caused by a single proxy cache. Two common architectures to implement the cooperative caching are hierarchical and distributed caching systems. Unfortunately, both architectures suffer from performance limitations. We propose an efficient hybrid caching architecture eliminating these limitations by using both the hierarchical and same level caches. Our performance evaluation with our investigated simulator shows that the proposed architecture offers the best of both existing architectures in terms of cache hit rate, the number of query messages from clients, and response time.

• The KIPS Transactions:PartC
• /
• v.15C no.6
• /
• pp.513-522
• /
• 2008

Efficient data dissemination is one of the important subjects for sensor networks. High accessibility of the sensed data can be kept by deploying the data centric storage approach in which data is stored over the nodes in the sensor network itself rather than external storages or systems. The advantage of this approach is its direct accessibility in a real-time without the severe burden on delay and power dissipation on the data path to the external storages or systems. However, if the queries from many users are concentrated to the few nodes with data, then the response time could be increased and it could lead to the reduction of network life time by rapid energy dissipation caused by concentrated network load. In this paper, we propose a adaptive data centric storage scheme based on proxy trajectory (APT) mechanism. We highlight the data centric storage mechanism by taking account of supporting large number of users, and make it feasible to provide high-performance accessibility when a non-uniform traffic pattern is offered. Storing data around the localized users by considering spatial data-access locality, the proxy trajectory of APT provides fast response for the users. The trajectory, furthermore, may help the mobile users to roams freely within the area they dwell.

• Journal of Communications and Networks
• /
• v.12 no.1
• /
• pp.52-66
• /
• 2010

Since large objects consume substantial resources, web proxy caching incurs a fundamental trade-off between performance (i.e., hit-ratio and latency) and overhead (i.e., resource usage), in terms of caching and relaying large objects to users. This paper investigates how and to what extent the current dedicated-server based web proxy caching scheme is affected by large file transfers in a high bandwidth campus network environment. We use a series of trace-based performance analyses and profiling of various resource components in our experimental squid proxy cache server. Large file transfers often overwhelm our cache server. This causes a bottleneck in a web network, by saturating the network bandwidth of the cache server. Due to the requests for large objects, response times required for delivery of concurrently requested small objects increase, by a factor as high as a few million, in the worst cases. We argue that this cache bandwidth bottleneck problem is due to the fundamental limitations of the current centralized web proxy caching model that scales poorly when there are a limited amount of dedicated resources. This is a serious threat to the viability of the current web proxy caching model, particularly in a high bandwidth access network, since it leads to sporadic disconnections of the downstream access network from the global web network. We propose a peer-to-peer cooperative web caching scheme to address the cache bandwidth bottleneck problem. We show that it performs the task of caching and delivery of large objects in an efficient and cost-effective manner, without generating significant overheads for participating peers.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.6
• /
• pp.1-6
• /
• 2014

The IoT (Internet of Things) is considered as a core technology to realize interconnected world. At this, companies composing ICT industry and standard organizations make efforts to accelerate it. IETF CoRE(Constrained RESTful Environment) working group standardized CoAP (Constrained Application Protocol) for the constrained device. CoAP has RESTful architecture and CoAP option is provided to use forward-proxy. The forward-proxy is used to translate protocol and perform requests on behalf of the client. However, communication between Internet based client and LLN(Low-power and Lossy Network) based CoAP server architecture has limitations to deploy real IoT service. In this architecture, problems like response delay, URI assignment and DoS attack can be occurred. To solve these problems, we propose the reverse-proxy based system. We consider both of static IoT and mobility IoT environments. Finally, our proposed system is expected to provide efficient IoT service.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04a
• /
• pp.286-288
• /
• 2002

SIP는 인터넷 텔레포니 신호(Internet Telephony Call)와 같은 멀티미디어 세션을 성립, 변경, 종료시킬 수 있는 응용계층의 호 제어 프로토콜이다. 또한, SIP 프록시 서버(Proxy Server)라는 네트일 호스트로 구축된 인프라를 통해 멀티미디어 통신을 원하는 네트윅상의 사용자를 찾아 멀티미디어 세션(Session)이 성립될 수 있도록 도와준다. SIP는 Request-Response 방식의 프로토콜이기 때문에 요청(Request)과 응답(Response)을 주고받는 일련의 트랜잭션(Transaction)으로 하나의 Task를 완성한다. 본 논문에서는 rfc2543을 기반으로 기본적인 SIP 트랜잭션을 위한 SIP 스택(Stack)의 설계 및 그 구현 방안을 제지한다.