• The KIPS Transactions:PartD
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• v.19D no.4
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• pp.299-306
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• 2012

To fulfill the complex user requirement, composition web service comprised of existing services is considered from the efficient and reusable point of view instead of making entirely new web service. However, with the growing the number of web services which provide the same functionality but differ in quality value, the service composition becomes a decision problem on which component services should be selected such that end-to-end QoS constraints by the client and overall QoS of the composition service are satisfied. QoS of service aspects is a determinant factor for selecting the services, since the performance of the composed service is determined by the performance of the involved component web service. In this paper, hybrid genetic algorithm is presented to select component services to take part in the QoS-aware composition. The local search method is used to be combined with the genetic algorithm to improve the individuals (component service) in population as well as composed service. The paper also presents a set of experiments conducted to evaluate the efficiency of selection algorithm using the real web service data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5231-5248
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• 2016

As a service-oriented paradigm, web service composition has obtained great attention from both academia and industry, especially in the area of cloud service. Nowadays more and more web services providing the same function but different in QoS are available in cloud, so an important mission of service composition strategy is to select the optimal composition solution according to QoS. Furthermore, the selected composition solution should satisfy the service level agreement (SLA) which defines users' request for the performance of composite service, such as price and response time. A composite service is feasible only if its QoS satisfies user's request. In order to obtain composite service with the optimal QoS and avoid SLA violations simultaneously, in this paper we first propose a QoS evaluation method which takes the SLA satisfaction into account. Then we design a service selection algorithm based on our QoS evaluation method. At last, we put forward a parallel running strategy for the proposed selection algorithm. The simulation results show that our approach outperforms existing approaches in terms of solutions' optimality and feasibility. Through our running strategy, the computation time can be reduced to a large extent.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1260-1281
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• 2015

As the number of services available on the Web increases, it is vital to be able to identify which services can be trusted. Since there can be an extremely large number of potential services that offer similar functionality, it is challenging to select the right ones. Service requestors have to decide which services closelysatisfy their needs, and theymust worry about the reliability of the service provider. Although an individual service can be trusted, a composed service is not guaranteed to be trustworthy. In this paper, we present a trust model that supports service discovery and composition based on trustworthiness. We define a method to evaluate trust in order to discover trustworthy services. We also provide a method to perform trust estimation for dynamic service composition, and we present results of two experiments. The proposed model allows for service requestors to obtain the most trustworthy services possible. Our mechanism uses direct and indirect user experience to discover the trustworthiness of the services and service providers. Moreover, composing services based on quantitative trust measurements will allow for consumers to acquire a highly reliable service that meet their quality and functional requirements.

• The KIPS Transactions:PartD
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• v.16D no.5
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• pp.737-746
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• 2009

The appearance of SOA affects business and IT environment and many studies on SOA is progressed in academics and industries. Service will increase extremely and make business opportunity by composing service. In addition, It will support it. However, studies on selection of a service composition target are insufficient. In this study, we propose a framework that select a service composition target so we use Analytic Hierarchy Process methodology. As a result of this study, we enabled service selection to apply functional/non-functional attributes of services, various stakeholder's view and some selection criteria with service composition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3293-3311
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• 2015

Cloud services are required to be composed as a single service to fulfill the workflow applications. Service composition in Cloud raises new challenges caused by the diversity of users with different QoS requirements and vague preferences, as well as the development of cloud computing having geographically distributed characteristics. So the selection of the best service composition is a complex problem and it faces trade-off among various QoS criteria. In this paper, we propose a Cloud service composition approach based on evolutionary algorithms, i.e., NSGA-II and MOPSO. We utilize the combination of multi-objective evolutionary approaches and Decision-Making method (AHP) to solve Cloud service composition optimization problem. The weights generated from AHP are applied to the Crowding Distance calculations of the above two evolutionary algorithms. Our algorithm beats single-objective algorithms on the optimization ability. And compared with general multi-objective algorithms, it is able to precisely capture the users' preferences. The results of the simulation also show that our approach can achieve a better scalability.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.127-129
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• 2003

시멘틱 웹 서비스의 최종적인 목표는 네트웍으로 연결된 프로그램들과 장치들이 사람의 명령 없이 긴밀하게 상호작용 하는 것이다. 시멘틱 웹은 정보의 의미를 알 수 있는 프레임워크를 연구하였는데, 이는 인공지능을 기반으로 하는 RDF. RDFS, DAML+OIL, OWL등의 언어를 기반으로 하여 연구되었다 시멘틱 웹 커뮤니티에서는 웹의 정보 뿐 아니라 서비스에도 정확한 의미를 부여하기 위해서 DAML+OIL 온톨로지 기반의 새로운 기술인 DAML-S 온톨로지 기술을 제안하였다. DAML-S는 Service. Service Profile. Service Model. Service Grounding의 4개의 상위 온톨로지로 구성되는데, 특히 Service Profile, Service Model 온톨로지와 인스턴스를 이용하여 사용자의 요구에 적합한 서비스 검색과 Composition01 가능하다. 사용자의 요구가 atomic 서비스가 아닌 여러 atomic 서비스들을 함께 이용해야 하는 경우에는 시멘틱 웹 서비스 검색 시스템 외에 추가적인 웹 서비스 Composer가 필요하게 된다. 본 논문에서는 사용자의 요구로부터 필요한 웹 서비스 chain을 구성함에 있어서 사람이 개입하지 않는 STRIPS 타입의 자동 웹 서비스 Composer를 제안한다.

• Journal of Korea Multimedia Society
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• v.18 no.9
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• pp.1091-1097
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• 2015

Internet-of-Things (IoT) becomes one of the most promising future paradigms, which foresees enormous amounts of interoperable things and heterogeneous services. The goal of IoT is to enable all things connected and brings all kinds information and services to people. However, such a great deal of information may lead to cognitive overload or restrain in productivity of people. Thus, it is a necessity to build intelligent mechanisms to assist people in accessing the information or services they needed in a proactive manner. Most of previous related mechanisms are built on well-defined web services and lack of consideration of constrained resources. This paper suggests a services composition method by adapting a hierarchical model, which is a graph-based model composed of four layers: Context Layer, Event Layer, Service Layer and Device Layer. With a such multi-layer graph, service composition can be achieved by the iteration of layer by layer. Then, to evaluate the effectiveness of this proposed hierarchical model, a real-life emergency response dataset is applied and the experimental results are composed with the general probabilistic method and indicate that the proposed method is help for compositing multiple services while considering given context and constrained resources.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.5
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• pp.394-405
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• 2004

To make Web Services the real applications, the efficient mechanisms for Web Services discovery, Web Services composition and Web Services execution must be provided. Among these issues, especially, Web Services composition plays the key roles in Web Services applications that are loosely coupled and composed applications consisted of primitive Web Service components. In this paper we demonstrate a new Web Service composition approach using ontologies. We apply ontologies to describe Web Services information such as Web Services input/output parameters, pre conditions, post conditions and other necessary management information. In this paper, we also introduce Action ontology and Object ontology to describe the functional properties of Web Services These ontologies offer semantic description of Web Services functionalities beyond the limitation of the current WSDL. We can achieve semantic interoperabilities between heterogeneous Web Services in terms of conceptual processing and realize semantic services composition. We implement semantic Web Services composition system called Genie based on service description ontologies.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.674-675
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• 2010

Since in web service composition, the same service may be offered by different providers with different Quality of Services (QoS) attributes, selection criteria are needed to select which Web Services will be considered for composition. Location of provider can be one of these criteria and intends to decrease the number of remote interactions between providers as well as reducing waiting time of service consumer. Therefore in this paper, we present technique for composing web services according to their location by semantically describing customer's goals and provider's web service capability by means of carefully designed ontology and logical expression.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.175-182
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• 2008

Context-aware service environment should provide many kinds of services according to users' requests. Users want a great variety of services. In response to their demands the service provider should make a new service every time. But making a new service every time may be inefficient even for a small number of users' requests. So, there are studies on how to efficiently support various and complex requests fFom users. In many researches, service compositions have lately attracted considerable attention. However, existing researches have mainly focused on Web services. So they are not proper to rapidly providing services in response to users' requests, especially In context-aware service environment. This paper proposes a rapid service composition using case-based reasoning. For evaluating the proposed algorithm we implement 'purchasing seTvice agent'. With this system, we compare our algorithm and the existing service composition algorithms.