• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2012년도 춘계학술발표대회
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• pp.586-589
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• 2012

Web Services have been utilized in a wide variety of applications and have turned into a key technology in developing business operations on the Web. Originally, Web Services can be exploited in an isolated form, however when no single Web Service can satisfy the functionality required by a user, there should be a possibility to compose existing services together in order to fulfill the user requirement. However, since the same service may be offered by different providers with different non-functional Quality of Service (QoS), the task of service selection for Web Service composition is becoming complicated. Also, as Web Services are inherently unreliable, how to deliver reliable Web Services composition over unreliable Web Services should be considered while composing Web Services. In this paper, we propose an approach on a QoS-aware Web Service selection for reliable Web Service composition. In our approach, we select and classify Web Services using Decision Tree based on QoS attributes provided by the client. Service classifier will improve selection of relevant Web Services early in the composition process and also provide flexibility to replace a failed Web Services with a redundant alternative Web Services, resulting in high availability and reliability of Web Service composition. We will provide an implementation of our proposed approach along with efficiency measurements through performance evaluation.

• 산업경영시스템학회지
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• 제42권3호
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• pp.217-231
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• 2019

The purpose of this study is to analyze the factors influencing consumers' selection of web-toon service through AHP (Analytic Hierarchy Process) analysis and to provide the strategy of web-toon service. To accomplish this study, theories, existing research and references related to AHP were sufficiently examined and selected the factors in the selection criteria. Surveys from consumers who used the web-toon service were conducted with selected factors. Through this, the results were analyzed by AHP analysis to find out the weighting values and the differences were examined and analyzed. The highest weighting factor in the first layer that consists of web-toon service was cinematic quality. The cinematic quality was the most important factor in the selection criteria of customers who use the web-toon service regardless of their preferred genre. Furthermore, it was confirmed that the weighting value or ranking changed in the second layer by genre. In this study, the effective basis of strategy were suggested by ranking the quantitative selection factors according to the preferred genre of consumers using web-toon services. In addition, This research provides some practical implications. That is, the web-toon service provider can easily recognize and respond to the customer's requirements, which factors are important when the customer selects a specific genre from the web-toon genre.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권1호
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• pp.38-59
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• 2022

Web services instances can be classified into two categories, namely trusted and untrusted from users. A web service with high throughput (TP) and low response time (RT) instance values is a trusted web service. Web services are not trustworthy due to the mismatch in the guaranteed instance values and the actual values achieved by users. To perform web services selection from users' attained TP and RT values, we need to verify the correct prediction of trusted and untrusted instances from invoked web services. This accurate prediction of web services instances is used to perform the selection of web services. We propose to construct fuzzy rules to label web services instances correctly. This paper presents web services selection using a well-known machine learning algorithm, namely REPTree, for the correct prediction of trusted and untrusted instances. Performance comparison of REPTree with five machine learning models is conducted on web services datasets. We have performed experiments on web services datasets using a ten k-fold cross-validation method. To evaluate the performance of the REPTree classifier, we used accuracy metrics (Sensitivity and Specificity). Experimental results showed that web service (WS1) gained top selection score with the (47.0588%) trusted instances, and web service (WS2) was selected the least with (25.00%) trusted instances. Evaluation results of the proposed web services selection approach were found as (asymptotic sig. = 0.019), demonstrating the relationship between final selection and recommended trust score of web services.

• 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.

• Journal of Computing Science and Engineering
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• 제6권2호
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• pp.89-104
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• 2012

In dynamic Web service environments, the performance of the Internet is unpredictable; the reliability and effectiveness of remote Web services are also unclear. Therefore, it can hardly be guaranteed that the quality of Web service (QoWS) attributes of Web services do not fluctuate with the dynamic Web service environments. When a composite service is planned in the context of dynamic service environments, there is another aspect which has not been taken into account by existing works, namely, concurrency - the fact that multiple requests to a composite service may arrive at the same time. Considering the dynamics of Web service environments and concurrency of requests, we propose in this paper a service selection scheme which adopts top-k dominating queries to generate a composition solution rather than only select the best composition solution for a given request. The experimental results have investigated the efficiency and effectiveness of our approach and shown that it outperforms baseline and traditional methods for service selection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권7호
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• pp.1252-1273
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• 2011

In Web Service Composition (WSC) area, services selection aims at selecting an appropriate candidate from a set of functionally-equivalent services to execute the function of each task in an abstract WSC according to their different QoS values. In despite of many related works, few of previous studies consider transactional constraints in QoS-aware WSC, which guarantee reliable execution of Composite Web Service (CWS) that is composed by a number of unpredictable web services. In this paper, we propose a novel global selection-optimal approach in WSC by considering both transactional constraints and end-to-end QoS constraints. With this approach, we firstly identify building rules and the reduction method to build layer-based Directed Acyclic Graph (DAG) model which can model transactional relationships among candidate services. As such, the problem of solving global optimal QoS utility with transactional constraints in WSC can be regarded as a problem of solving single-source shortest path in DAG. After that, we present Graph-building algorithms and an optimal selection algorithm to explain the specific execution procedures. Finally, comprehensive experiments are conducted based on a real-world web service QoS dataset. The experimental results show that our approach has better performance over other competing selection approaches on success ratio and efficiency.

• 정보처리학회논문지D
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• 제13D권4호
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• pp.603-612
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• 2006

최근 웹 서비스 분야는 SOA(Services-Oriented Architecture)에 대한 관심의 증가와 B2B 시장의 성장으로 인해 차세대 IT 패러다임으로 급부상하고 있다. UDDI(Universal Description, Discovery and Integration)를 통한 서비스 발견은 오직 기능적 측면에만 기반을 두기 때문에, 서비스의 사용 빈도와 상호간의 신뢰성에 미치는 영향은 고려하지 않았다. 즉, 웹 서비스의 비기능적 측면인 품질은 소비자와 제공자 상호간에 성공을 위한 중요한 요인이 될 것이며, 이에 품질을 고려한 웹 서비스 선정 방법이 요구된다. 본 논문에서는 서비스 소비자의 입장에서 소비자가 원하는 최적의 품질을 제공하는 서비스를 찾도록 도와주는 에이전트 기반 품질 브로커 아키텍처와 선정 프로세스를 제안한다. 웹 서비스와 같이 분산되고 이질적인 환경에서 에이전트에 관한 이론들은 널리 받아들여지고 있으므로 제안하는 시스템 아키텍처에 적합하다. 본 논문에서는 웹 서비스 선정에 관한 기존 연구의 문제점을 개선하기 위해 평가과정에서 QoS와 CoS를 고려하였으며, 평가 방법으로 다기준 의사결정 기법들 중에서 웹 서비스 선정에 가장 적합하다고 판단된 PROMETHEE(Preference Ranking Organization MeTHod for Enrichment Evaluations)를 사용하였다. PROMETHEE는 비교 서비스들이 추가되거나 삭제되더라도 이원비교를 다시 수행해야 하는 문제를 극복할 수 있는 장점이 있다. 본 논문에서는 제시한 선정 프로세스를 검증하기 위하여 서비스 조합 시나리오를 갖는 사례 연구를 제시하였다. 사례 연구에서 웹 서비스 선정 프로세스는 소비자 관점의 품질 측정값과 정의된 서비스 레벨을 바탕으로 의사 결정 문제를 기술하였다.

• 한국컴퓨터정보학회논문지
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• 제19권12호
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• pp.209-218
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• 2014

모바일 웹 서비스 사용자가 증가함에 따라 품질을 고려한 모바일 웹 서비스 선택이 중요한 이슈로 여겨지고 있다. 품질계약은 서비스 품질의 수준을 명세한 웹 서비스 제공자와 웹 서비스 사용자간의 협약으로 웹 서비스 사용자는 품질계약을 통해 명세한 서비스 품질의 수준을 보장받을 수 있다. 본 논문에서는 품질을 고려하여 모바일 웹 서비스를 선택하기 위하여 중개자 기반의 프레임워크를 제안한다. 모바일 사용자들은 무선망에서 서비스 중개자를 통하여 웹 서비스를 요청할 수 있다. 서비스 중개자는 에이전트를 이용하여 웹 서비스 품질을 모니터링하며 서비스 품질계약에 위반사항이 발생하면 웹 서비스 제공자와 사용자에게 위반사항이 발생하였음을 통보함으로써 서비스 품질을 관리한다. 본 논문에서는 모니터링을 위하여 신뢰성, 응답시간, 그리고 가격 품질요소들을 사용하였으며 모바일 사용자들은 서비스 중개자를 통하여 품질 좋은 웹 서비스를 선택할 수 있다.

• 정보처리학회논문지D
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• 제19D권4호
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• pp.299-306
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• 2012

웹 서비스 합성은 기존 단일 서비스들을 합성해서 제공하는 방식으로, 사용자의 다양한 요구를 만족시키기 위해서 새로운 웹 서비스를 만들기보다는 재사용과 효율성 측면에서 고려되고 있다. 그러나 유사 기능을 제공하지만 다른 서비스 품질을 제공하는 서비스의 수가 증가함에 따라, 서비스 합성 문제는 사용자의 전역 제약 조건과 합성서비스의 QoS를 만족시키기 위해서 어떤 구성 서비스들을 선택해야 하는지에 대한 선택 문제가 되었다. 합성 서비스의 수행은 구성 서비스의 수행에 의해 결정되므로, 합성 서비스에 포함될 구성 서비스 선택을 위해서는 가격, 지속성, 응답시간과 같은 QoS에 대한 고려는 필수적이다. 본 논문에서는 합성 서비스 선택 시 QoS를 고려한 기법으로 합성 유전자 알고리즘을 적용하였다. 유전자 알고리즘에 지역 탐색 방법을 결합하여 빠른 시간 안에 합성 서비스의 전반적인 QoS뿐만 아니라 구성 서비스의 품질을 향상 시킬 수 있는 서비스 선택 기법을 제시한다. 본 연구는 실제 웹상에 존재하는 실제 데이터를 이용하여 서비스 증가에 따른 시간 측정 및 최적화 정도를 비교 분석을 통해 선택 알고리즘의 유효성을 검증하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 춘계학술발표대회
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• pp.1307-1310
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• 2009

Web services provide the possibility of dynamically integrating distributed service components scattered over the Internet to fulfill sophisticated business demands. However due to today's wide variety of services offered to perform a specific task, it's essential that users are supported in the eventual selection of appropriate services. An example of web services for which selection of appropriate services will be crucial is Auto Repair Services. Selecting proper service from a variety of Auto Part Shops would be result of delivering high-quality service and minimizing Auto Repair Service customer's waiting time. Therefore, in this research to assist selecting proper service, we present Functional-Level Mediator and illustrate its usage in matching customer's and web service's goals. Five matching cases have been analyzed and results from experiment have been shown. Also, taking advantage of implementing multithreaded web services which reflects concurrent activity in the real world more naturally, we have significantly minimized customer's waiting time at Auto Repair Service.