• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.955-962
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• 2008

Multicast Strategy is one of the cost-saving methods in the large scale VOD environment. However, it does involve complicated problems to implement VCR-like interactions for user's convenience in the multicast streaming system under considering the limited-server and the network's bandwidth in the multicast-transmission system. Therefore, the proper solution of settling such a problem is necessary. Thus, this paper which revised P2Patching[l] proposes LGST(Level Group Streaming Technique) which supports the VCR's function through cooperation among peers with heterogeneous bandwidth under the environment of P2P. This strategy can reduce latency by improving the acceptance of server and using the bandwidth of network efficiently. And for evaluate the proposed scheme's performance, I simulated the performance of streaming delivery topology and streaming quality in comparison with P2Patching. In evaluation to service request refusal ratio and service quality according to bandwidth decrement, the result of simulation shows that proposed LGST improves about $11{\sim}18%$ of performance than P2Patching. In the test of latency recovery according to fault probability and influence of VCR function operation duration, it shows similar performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.145-152
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• 2010

With the recent development of the ubiquitous computing technology, there are increasing interest and research in technologies such as sensors and RFID related to information recognition and location positioning in various ubiquitous fields. Especially, RTLS(Real-Time Locating Services) dealing with spatio-temporal data is emerging as a promising technology. For these reasons, the ISO/IEC published the RTLS standard specification for compatibility and interoperability in RTLS. Therefore, in this paper, we designed and implemented Spatio-temporal Query Processing Systems for efficiently managing and searching the incoming Spatio-temporal data stream of moving objects. Spatio-temporal Query Processing Systems's spatio-temporal middleware maintains interoperability among heterogeneous devices and guarantees data integrity in query processing through real time processing of unceasing spatio-temporal data streams and two way synchronization of spatio-temporal DBMSs. Web Server uses the SOAP(Simple Object Access Protocol) message between client and server for interoperability and translates client's SOAP message into CQL(Continuous Query Language) of the spatio-temporal middleware. Finally, this thesis proved the utility of the system by applying the spatio-temporal Query Processing Systems to a real-time Locating Services.

• The KIPS Transactions:PartD
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• v.15D no.1
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• pp.131-138
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• 2008

This paper describes the implementations of the first application service based on embedded Linux; Mobile Teller which uses WiBro network for data communications and CDMA network for voice communications. Currently, with the appearance of WiBro service, dual-mode terminals which support two heterogeneous networks are available. But, the development of applications which effectively use these networks for providing better service to user is rarely prepared. At Mobile Teller, when a sender on a dual-mode terminal types texts, the texts are transmitted to a TTS server located in the Internet through WiBro network. Subsequently, the TTS server converts the texts into voices and transmits the voice data to the dual-mode terminal. At last the dual-mode terminal sends the voice to the receiver through the CDMA network. In case of noisy environment or when a user has difficulty in speaking, Mobile Teller makes voice communication possible

• Journal of KIISE:Software and Applications
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• v.26 no.11
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• pp.1298-1305
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• 1999

네트워크 및 분산 처리 기술의 발달로 분산 환경에서 동작하는 응용 프로그램에 대한 생산성 향상이 요구되고 있다. 본 논문에서는 MVC(Model, View, Controller) 패턴을 기반으로 하는 분산 응용 프로그램의 생산성 향상을 위해, 조립식 분산 응용의 작성을 지원하는 분산 객체 조립기, DOC(Distributed Object Composer)를 소개한다. 분산 객체 조립성의 기반이 되는 DOC의 구성적{{) '전체'를 창조해 내기 위해 여러 요소들을 결합, 배치하여 하나의 예술작품을 성립시키는 방법. 모아서 조립한다는 의미.}} 인터페이스(Structural Interface)는 기존 객체지향 기술의 절차적 인터페이스(Procedural Interface)에 비해 콤포넌트 재사용성을 개선하고, 분산 응용의 신속한 개발을 지원하여, 소프트웨어의 생산성 및 확장성을 향상시킨다. 또한, DOC 방식으로 모델링하고 구현한 공급망 관리(Supply Chain Management: SCM) 응용 프로그램의 조립식 작성을 통해, DOC의 실시간 정보 처리 및 조립 기능을 보인다.DOC는 이질적인 통신 환경에서 클라이언트와 서버 객체간의 네트워크 투과성을 제공하는 미들웨어, CORBA를 기반으로 한다. 또한, 분산 객체들 간의 상호작용을 자동 처리하기 위해 Java의 관찰자/피관찰자(Observer/Observable)를 확장한 분산 관찰자/피관찰자 패턴을 정의하여 DOC와, 서버 및 클라이언트의 분산 응용 객체들을 정의하기 위한 인터페이스에 적용한다.Abstract Due to the availability of advances in network and distributed processing technologies, the enhanced productivity of application software that runs on distributed environment is demanded. In this paper, we introduce the Distributed Object Composer (DOC) that supports the structural composition of distributed applications for the enhanced productivity of MVC (Model, View, Controller) pattern-based application programs. The structural interface of DOC that is the basis for the composibility of distributed objects increases the reusability of software components and provides better software productivity and extendibility than the procedural interface of the traditional object-oriented technology by supporting rapid constructions of distributed applications. In this paper, we also discuss the real-time information processing and composibility features of DOC by applying the DOC mechanism to the Supply Chain Management (SCM) application.DOC is implemented using the CORBA middleware that supports the network transparency between client and server objects on heterogeneous communication environments. We apply the distributed Observer/Observable pattern that extends the Observer/Obseverable of Java to DOC itself and distributed client/server objects as their interface definitions for the automatic interactions of distributed objects.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.2
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• pp.103-114
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• 2007

The existing handover authentication schemes have authentication delay and overhead of the authentication server since they have been separately studied handover authentication at the link layer and the network layer. This paper proposes a handover authentication scheme initiated by Mobile Node on FMIPv6 based mobile access networks. The main idea of the paper is to generate a session key at the mobile node side, and transfer it to the next Access Router through the authentication server. Also, the scheme has a hierarchical key management at access router. There are two advantages of the scheme. First, the generated session key can be utilized for protecting the binding update messages and also for access authentication. Second, hierarchical key management at the access router reduced the handover delay time. The security aspects on the against PFS, PBS, and DoS attack of proposed scheme are discussed.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.125-135
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• 2010

Mobile office is becoming common as advances in mobile devices such as PDAs, Smart-phones, or wireless Internet. In this paper, we construct a mobile office environment on a geotechnical information system(GIS). Especially, web services and XML technology combined with SOA (service oriented services) are adopted for various types of mobile devices and services in a minimum cost. Web service and XML can provide an excellent SW reusability, extensibility, and interoperability even for heterogeneous distributed systems. Applications can exploit web services by just knowing server's address. Prototype system integrates a client in Visual Basic.Net and server in Java via the web services and XML data exchange. We verify effectiveness of the approach through the implementation of prototype system.

• Journal of Korea Multimedia Society
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• v.7 no.1
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• pp.12-26
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• 2004

In the past, geographic data is constructed and serviced through independent formats of its own according to each GIS(Geographic Information System). Recently the provision of interoperability in GIS is important to efficiently apply the various geographic data between conventional GIS's. Whereupon OGC(Open GIS Consortium) proposed GML(Geography Markup Language) to offer the interoperability between heterogeneous GISs in distributed environments. The GML is an XML encoding for the transport and storage of geographic information, including both the spatial and non-spatial properties of geographic features. Also, the GML includes Web Map Server Implementation Specification to service the GML documents. Accordingly the prototype to provide the reciprocal interchange of geographic information between conventional GIS's and GML documents is widely studied. In this paper, we propose a mapping method of geographic in formation between spatial database and GML for the prototype to support the interoperability between heterogeneous geographic information. For this method, firstly the scheme of converting geographic in Formation of the conventional spatial database into the GML document according to the GML specification is explained, and secondly the scheme to transform geographic information of GML documents to geographic data of spatial database is showed. Consequently, the proposed method is applicable to the framework for integrated geographic information services based on Web by making an offer the interoperability between already built geographic information of conventional GIS's using a mapping method of geographic information between spatial database and GML.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.313-320
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• 2003

This paper design and implements a synchronized agent mechanism that be able to synchronize SFT (Slow Frequency Transaction) data among e-business processes in distributed environment. This synchronized agent system is adopted to use mobile agent to guarantee the interoperability of the distributed processes and to solve some problems at the client/server architecture and proposes a policy to synchronize data of e-business processes on the any platforms of distributed heterogeneous systems. The proposed synchronization policy is based on the time-stamp transaction with the system priority on the unicasting transportation.

• Journal of Information Processing Systems
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• v.3 no.2
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• pp.82-88
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• 2007

Web services are the new building block of today's Internet, and provides interoperability among heterogeneous distributed systems. Recently in web services environment, security has become one of the most critical issues. The hackers attack one of fragile point and can misuse legitimate user privilege because all of the connected devices provide services for the user control and monitoring in real time. Also, the users of web services must temporarily delegate some or all of their rights to agents in order to perform actions on their behalf. This fact risks the exposure of user privacy information. In this paper, we propose secure delegation model based on SAML that provides confidentiality and integrity about the user information in distributed systems. In order to support privacy protection, service confidentiality, and assertion integrity, encryption and a digital signature mechanism is deployed. We build web service management server based on XACML, in order to manage services and policies of web service providers.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.59-66
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• 2017

Cloud computing has evolved into a core computing infrastructure for the internet that encompasses content, as well as communications, applications and commerce. By providing powerful computing and communications capabilities in the palm of the hand everywhere with a variety of smart devices, mobile applications such as virtual reality, sensing and navigation have emerged and radically changed the patterns people live. The data that is generated is getting bigger. Cloud computing, on the other hand, has problems with system load and speed due to the collection, processing and control of remote data. To solve this problem, fog computing has been proposed in which data is collected and processed at an edge. In this paper, we propose a system that dynamically selects a fog server that acts as a cloud in the edge. It serves as a mediator in the cloud, and provides information on the services and systems belonging to the cloud to the mobile device so that the mobile device can act as a fog. When the role of the fog system is complete, we provide it to the cloud to virtualize the fog. The heterogeneous problem of data of mobile nodes can be solved by using mDBaaS (Mobile DataBase as a Service) and we propose a system design method for this.