• Steel and Composite Structures
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• 제5권2_3호
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• pp.193-202
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• 2005

This paper describes recent developments in composite construction and their effect on codified design procedures in the UK. Areas of particular interest include: rules on shear connection, design of beams with web openings, serviceability limits, such as floor vibrations, and fire safe design. The design of cellular beams with regular circular openings now includes generalized rules for web-post buckling, and for the development of in-plane moment in the web-post for asymmetric sections. Closed solutions for the maximum shear force due to limits on web-post bending or buckling are presented. The fire resistance of cellular beams is also dependent on the temperature of the web-post, and for closely spaced openings. It is necessary to increase the thickness of fire protection to the web. For serviceability design of beams, deflection limits and natural frequency and response factor for vibration are presented. It may be necessary to use stricter limits for certain applications.

• 한국소음진동공학회논문집
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• 제23권12호
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• pp.1103-1110
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• 2013

Based on the string, Euler beam, and Timoshenko beam theories, the transfer functions of axially translating web system to predict the lateral tracking are introduced in this paper. In addition, total transfer function of a multi-span web handling system is developed by the combination of the transfer functions of each single span. Experiments and computations are carried out and the results obtained for the Timoshenko beam model are compared with those of other models. The comparison indicates that the predictions from the Timoshenko and Euler beam models are quite different from that of the classical string model in both the gain and phase response. The results are expected to help in the development of high fidelity models of web tracking systems within a general computational framework.

• 한국IT서비스학회지
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• 제6권2호
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• pp.125-143
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• 2007

IT Services market is growing rapidly in the business industry and SOA-based Web Services have been introduced as an effective vehicle for the integration of enterprise-wide applications within organizations. The number of publicly available Web Services is ever increasing recently in a variety of areas, and as the number of public Web Services increases, there will be many Web Services with the same functionality. These services, however, will vary in their QoS properties, such as price, response time and availability, and it is very important to choose a right service while satisfying given QoS constraints. This paper addresses the issue of selecting composite Web Services which involves conditional branches in business processes. It is essential to have any conditional branches satisfy the global QoS constraints at service selection phase, since the branches are chosen to execute at run-time dynamically. We proposed service selection procedures for basic structure of conditional branches and explained them by examples. Experiments were conducted to analyze the impact of the number of candidate services and service types on the time of finding service solutions.

• ETRI Journal
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• 제31권2호
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• pp.173-181
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• 2009

The growth of the World Wide Web and web-based applications is creating demand for high performance web servers to offer better throughput and shorter user-perceived latency. This demand leads to widely used cluster-based web servers in the Internet infrastructure. Load balancing algorithms play an important role in boosting the performance of cluster web servers. Previous load balancing algorithms suffer a significant performance drop under dynamic and database-driven workloads. We propose an estimation-based load balancing algorithm with admission control for cluster-based web servers. Because it is difficult to accurately determine the load of web servers, we propose an approximate policy. The algorithm classifies requests based on their service times and tracks the number of outstanding requests from each class in each web server node to dynamically estimate each web server load state. The available capacity of each web server is then computed and used for the load balancing and admission control decisions. The implementation results confirm that the proposed scheme improves both the mean response time and the throughput of clusters compared to rival load balancing algorithms and prevents clusters being overloaded even when request rates are beyond the cluster capacity.

• 한국정보과학회논문지:시스템및이론
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• 제35권3호
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• pp.111-119
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• 2008

본 논문에서는 차별화 서비스를 지원하는 웹 서버의 응답시간 성능을 향상시키기 위해 기존의 동적 성능 분리 기법에 퍼지 기법을 접목한다. 특히, 클러스터 기반 웹서버 시스템의 부하량에 대한 판단 기준 흑은 사용자 요청율 및 동적요청 비율 변화시에 발생하는 애매모호한 상황을 효과적으로 반영하기 위해, 퍼지제어 기법에 기초한 로드분배 메커니즘을 제안하였다. 이를 통해, 기존의 퍼지 기법을 활용하지 않은 성능분리 기법과 퍼지기법을 활용한 경우에 대해 응답시간(95-percentile of Response Time) 성능비교 평가를 통해 퍼지기반의 성능분리 기법이 차별화 서비스 시스템의 성능을 더욱 강건하고 효율적으로 향상시킬 수 있다는 점을 검증하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(3)
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• pp.165-168
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• 2002

This paper has been designed and implemented of web security system using RF card A security mechanism that was proposed in this paper provides web services on card reader reads RF card of user only. In this paper, user authentication and server authentication was provided by challenge/response mechanism. Also, this system was provides confidentiality of communication messages.

• 한국정보시스템학회지:정보시스템연구
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• 제16권2호
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• pp.35-49
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• 2007

The web monitoring is a procedure to detect and monitor the change of a particular information from the web site. In this paper, we propose a monitoring system to survey the response time for the customers chi an internet shopping mall. This system we designed, decreases the network overload and guarantees the accuracy as well as the reliability of the information by using an interactive agent. This interactive agent we constructed, is written in Java and controlled by the high-level information such as the index or the robot. from the N web site, we extracted the web monitoring results of keyword "LCD Monitor" and verified our system's efficiency. The performance of the system is tested and the result is illustrated.

• Steel and Composite Structures
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• 제18권3호
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• pp.757-773
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• 2015

This work attempts to implement multiple regression analysis (MRA) for modeling and predicting the shear buckling strength of a steel beam with corrugated web. It was recognized from theoretical and experimental results that the shear buckling strength of a steel beam with corrugated web is complicated and affected by several parameters. A model that predicts the shear strength of a steel beam with corrugated web with reasonable accuracy was sought. To that end, a total of 93 experimental data points were collected from different sources. Then mathematical models for the key response parameter (shear buckling strength of a steel beam with corrugated web) were established via MRA in terms of different input geometric, loading and materials parameters. Results indicate that, with a minimal processing of data, MRA could accurately predict the shear buckling strength of a steel beam with corrugated web within a 95% confidence interval, having an $R^2$ value of 0.93 and passing the F- and t-tests.

• 정보처리학회논문지A
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• 제8A권4호
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• pp.293-298
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• 2001

본 논문에서 구현한 더블큐 웹서버는 동시에 들어오는 요청들을 두 가지로 분류하여 서비스한다. 캐쉬되어 있는 문서를 요구하는 요청은 서비스 큐에 넣고, 캐쉬되지 않은 문서를 요구하는 요청은 기다림 큐에 넣는다. 더블큐 웹서버는 서비스 큐의 모든 문서를 서비스 한 후 기다림 큐의 요청을 서비스한다. 이 방식은 디스크 접근 오버헤드를 줄이기 위해 캐쉬 된 문서의 서비스를 우선하는 정책으로 아파치 웹서버와 비교 실험 결과 서버의 성능과 평균 사용자 응답 시간을 향상시켰다.

• 대한원격탐사학회지
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• 제33권4호
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• pp.391-400
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• 2017

Geo-based application services linked with the Open Geospatial Consortium (OGC) Web Processing Service (WPS) protocol have been regarded as an important standardized framework for of digital earth building in the web environments. The WPS protocol provides interface standards for analysis functionalities within geo-spatial processing in web-based service systems. Despite its significance, there is few performance tests of WPS applications. The main motivation in this study is to perform the comparative performance test on WPS standards. Test system, which was composed of WPS servers, WPS framework, data management module, geo-based data processing module and client-sided system, was implemented by fully open source stack. In this system, two kinds of geo-based image processing functions such as cloud detection and gradient magnitude computation were applied. The performance test of different server environments of non-WPS, synchronous WPS 1.0 and asynchronous WPS 2.0 was carried out using 100 threads and 400 threads corresponds client users on a web-based application service. As the result, at 100 threads, performance of three environments was within an adjacent range in the average response time to complete the processing of each thread. At 400 threads, the application case of WPS 2.0 showed the distinguished characteristics for higher performance in the response time than the small threads cases. It is thought that WPS 2.0 contributes to settlement of without performance problems such as time delay or thread accumulation.