• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.355-364
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• 2004

These days, various clustering technologies have been adopted to construct web sites. High performance hardware switches have good performance, but have disadvantage of high cost for constructing small and middle-sized web sites. Now a days, many sites have been constructed with the LVS (Linux Virtual Server), which is free of charge and has good performance. Having a centralized load balancing with one front-end, the LVS causes a bottleneck when it receives all at once. In the paper, we suggest a way to remove the LVS bottleneck by providing multiple front-ends. In this architecture, all of cluster nodes act as both a front-end and a back-end. When the load of a node receiving requests is not large enough, the node responds to the client directly. When the load of a node is large enough, the node send the request to a node which is selected by a scheduling algorithm. The scheduling algorithm is discussed to balance loads between servers. While single front-end cluster raises the throughput curvedly, the multiple front-end cluster raises the throughput linearly.

• Korean journal of food and cookery science
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• v.23 no.3 s.99
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• pp.327-336
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• 2007

Life-style factors often include social relationships as well as consumption, entertainment and dress patterns. They also typically reflect an individual's attitudes, values and worldview. Life-style types have become and an important factor for segmenting customer markets ever since significant relationships between life-style and customers' behavior was proven. This study examined the relationships between the life-styles of young customers' and the important attributes of foodservice encounters. Factors analysis with VARIMAX and K-means cluster analysis were conducted to group the subjects by life-style. According to the factors analysis, four underlying dimensions were identified and labeled: (1) 'actively fashioned', (2) 'luxury picky', (3) 'healthy toward', and (4) 'utilitarian leisure'. Based on the factor scores derived from the factors analysis, the K-means cluster analysis classified three groups as statistically significant using ANOVA(p<0.05). The overall mean score for the 3rd cluster 'trendy-active picky' was higher than the other two clusters, and represented very picky attitudes about foodservice attributes. The 3rd cluster also seemed to apply higher standards to all of the foodservice attributes. By order of importance, the most important attributes of the 2nd cluster 'pursue-utilitarian leisure' were food serving time, automation systems, server's hygienes, employee kindness, time in line, and menu variety. In spite of low concerns for the life-style attributes, the first cluster 'passively indifferent' recognized menu variety, food sanitation, food serving time, server's hygiene, menu price, air circulation, and room temperature as important. These results suggest that young diners in Korea could be classified by their diverse life-styles that are represented as trendy, utilitarian, and indifferent and will hopefully contribute to the foodservice industry's ability to segment customer characteristics by different life-styles in Korea.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.11-18
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• 2011

The increasing of web users load to the excessive transmission traffic and system overload problems. To solve these problems, cluster systems are studied. In conventional cluster systems, when the request size is large owing to such types as multimedia and CGI, the particular server load and response time tend to increase even if the overall loads are distributed evenly. In this paper, we consider the methodology of efficient resource usage, specially distributed web cluster system. We develope an algorithm that distributes the load on the web cluster system to use the system resources, such as system memory equally. The response time is chosen as a performance measure on the various clustering models. And based on the concurrent user to the web cluster system, the response time is also examined as the number of users increases. Simulation experience with this algorithm shows that the response time and average throughput seems to have a good results compare to those with the other algorithm.

• Smart Media Journal
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• v.8 no.4
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• pp.46-52
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• 2019

The size of data generated and collected at industrial sites or in public institutions is growing rapidly. The existing data processing server often handles the increasing data by increasing the performance by scaling up. However, in the big data era, when the speed of data generation is exploding, there is a limit to data processing with a conventional server. To overcome such limitations, a distributed cluster computing system has been introduced that distributes data in a scale-out manner. However, because distributed cluster computing systems distribute data, inefficient use of network bandwidth can degrade the performance of the cluster as a whole. In this paper, we propose a scheme that compresses data when transmitting data in a Hadoop cluster considering network bandwidth. The proposed scheme considers the network bandwidth and the characteristics of the compression algorithm and selects the optimal compression transmission scheme before transmission. Experimental results show that the proposed scheme reduces data transfer time and size.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.9-15
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• 2007

As the Internet grows and the mass multimedia data become popular, the storage system migrates from DAS, where the storage and the server are directly connected, to SAN and NAS. SAN connects the storages with a separate network, and NAS provides only file services, connects the storages with IP network. However, SAN and NAS can not fulfill the needs for companies if used separately, thus are asked to be integrated. In this research, we propose an efficient data sharing method which employees the concept of GMC, Croup Master Cache for the integrated environment of SAN and NAS. GMC is based on MCI, Metadata server and Cluster system Integration, but tries to solve the high expansion cost problem with MCI. We introduce the basic concept of GMC, compare the performance of GMC with that of MCI using computer simulation.

• The KIPS Transactions:PartA
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• v.13A no.3 s.100
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• pp.211-222
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• 2006

The cluster system with shared-nothing storage cannot escape from the problem of skewed request toward specific contents. This paper, therefore, suggests streaming method using MDC (Multiple Description Coding) instead of using single original content; this method is able to cope with skewed request in shared-nothing storage server as well as to continue to provide services in case of the system failure. Also, the system can support adaptive streaming service according to user player type, network status, the load of server, and client.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.103-106
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• 2004

A wireless Internet proxy server cluster has to Distillation and Caching functions in order that a user on wireless internet can use existing wired internet service. Distillation function works to distill HTML documents and included images according to the defined preference by a user. When a user requests repeatedly, Caching function decreases response time by reusing original and distilled images or HTML documents. In this paper, we proposed enhanced distillation and caching functions. We performed experiments using 16 PCs and experimental results show the effectiveness of the proposed system compared to the existing system.

• The KIPS Transactions:PartC
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• v.8C no.4
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• pp.379-388
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• 2001

인터넷을 이용한 전자상거래(e-commerce)가 확산되면서 중소규모의 다중 서버를 클러스터화하여 클라이언트의 요청에 대한 응답을 수행하는 네트웍 서비스에 대한 요구가 증대하고 있다. 이러한 웹서버 클러스터 환경의 요청을 위해서는 TCP정보나 요청되는 대상의 컨텐트(content) 정보를 이용하여 라우팅을 수행하는 라우터의 구현이 필수적이다. 이러한 TCP 라우팅이나 컨텐트 라우팅의 구현을 전적으로 소프트웨어에 의존하는 경우 전송속도의 저하가 발생할 우려가 있다. 이는 기존의 TCP 커넥션 설정과 이 TCP 커넥션을 이용한 데이터 전송이 라우팅을 고려하지 않은 가상의 점대점(point-to-point) 연결구조를 갖기 때문이다. 따라서, 본 논문에서는 보안세션 라우팅을 고속화시키기 위하여 TCP 커넥션 고속화를 기반으로 보안세션의 재사용성을 향상시키는 웹서버 클러스터 환경에 최적화된 디스패칭(dispatching) 기법을 제시하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1437-1447
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• 1997

This paper proposes a cluster-based PCS(Personal Communication Services) network architecture to support increased signaling and control traffic. The procedures are presented to serve the mjobility management and the efficient procesing of the call-control functional using distributed servers. Especially when call-setups are made within a cluster, this distributed servers. Especially when call-setup time and the amount of control traffic of H-HLS (High level Home Location Server) in the network as L-HLS(Low lever Home Location Server) serves the call on behalf of H-HLS. Performance and reliability of the architecture have been also cairried out.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.96-112
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• 2020

Solving the disclosure problem of sensitive information with the k-nearest neighbor query, location dummy technique, or interfering data in location-based services (LBSs) is a new research topic. Although they reduced security threats, previous studies will be ineffective in the case of sparse users or K-successive privacy, and additional calculations will deteriorate the performance of LBS application systems. Therefore, a model is proposed herein, which is based on geohash-encoding technology instead of latitude and longitude, memcached server cluster, encryption and decryption, and authentication. Simulation results based on PHP and MySQL show that the model offers approximately 10× speedup over the conventional approach. Two problems are solved using the model: sensitive information in LBS application is not disclosed, and the relationship between an individual and a track is not leaked.