• The Journal of Society for e-Business Studies
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• v.12 no.2
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• pp.1-16
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• 2007

Recently the computing environment has been moved to open architectures that include Web technologies. Web Service is one of import component of the new paradigm. This paper presents a design and implementation of GIS Web Service for mobile devices. As many mobile devices are equipped with GPS (Global Positioning System), it is required to handle the position information more effectively. We have extended the proxy program in the client device to actively send the context information to the server. Based on the context information the server determines the optimal service mode to a particular client. A working example of location?based GIS Web Service is also presented. By using Web Service standards and XML messages we can achieve the maximal interoperability for heterogeneous mobile devices.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.529-530
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• 2009

웹 브라우저 환경에서 통신 및 화면 갱신 기능을 제공하기 위해서 최근까지 ActiveX를 제공하였다. 하지만 ActiveX 배포에 따른 보안 문제 또는 Spyware 등으로 인한 개인 정보 노출 가능성을 배제할 수 없게 되었다. 따라서 본 논문에서 제안하는 웹 브라우저 환경에서의 통신 모듈 및 화면 갱신 기법을 통해서 ActiveX의 단점을 보완하려 한다. 또한, 여러 분야에서 적용 가능하지만 NMS 원격 감시 모니터링의 시뮬레이션을 통해서 적용 가능성을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.107-110
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• 2007

클라이언트-서버 구조의 스트리밍 시스템은 서버의 가용 능력에 따라 클라이언트의 개수가 제한되는 단점을 가진다. 본 논문에서는 인터넷 방송 시스템의 확장성과 안정성을 지원하기 위해 P2P에 기반한 모델을 제시한 후, 프로토타입 시스템을 설계 및 구현하였다. 본 논문에서 구현한 시스템 OmniCast264는 H.264 비디오 스트림을 제공하는 인코딩서버와 스트리밍서버, 피어노드, 프록시 서버로 구성된다. OmniCast264는 스트리밍 부하의 분산화, 실시간성, 에러 발생에 따른 강건함, 계층의 모듈화등의 개념을 가지고 있기 때문에 대용량의 인터넷 방송에 적합하다고 할 수 있다. 마지막으로 PC들을 병렬 및 직렬 구조의 유형으로 나누어 P2P를 구성한 후, OmniCast264의 성능을 평가하여 실시간 재생이 가능함을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.569-571
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• 2015

본 논문에서는 IoT(Internet of Things) 표준 프로토콜인 IETF(Internet Engineering Task Force) CoAP(Constrained Application Protocol)을 이용한 실내 자원 제어 구조를 제시한다. 제안한 웹 기반 실내 환경 제어 구조에서는 웹 서버에 프록시(proxy)와 자원 디렉토리(RD : Resource Directory) 기능을 포함하고 있다. 이를 통해 CoAP 프로토콜을 통해 저전력, 소규모의 노드를 웹 서버에 등록하고, 프록시의 HTTP과 CoAP 메시지 변환 기능을 이용하여 사용자가 웹브라우즈를 이용하여 실내 환경을 제어할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.1-10
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• 2012

Mobility and quality of service (QoS) are becoming the more important issues in wireless communications. The traditional Internet service is expanding into new access media and applications. Since wireless communication services are accompanied by frequent handovers at remote sites, scalable and fast handover has become a prerequisite for ubiquitous communication. In this paper, the differentiated service (Diffserv) model is deployed in heterogeneous proxy mobile IPv6 (PMIPv6) networks to satisfy the QoS guaranteed service and fast handover requirements. The operational procedures for QoS guaranteed global roaming are presented. In addition, QoS management and handover cost evaluation schemes based on a mobile host's movement scope are proposed. This paper analyzes the reduction in handover delay in a network-based localized mobility management framework. We propose and analyze a PMIPv6 optimized with a global mobile access gateway (G-MAG), which is a network-based entity, to further improve the handover performance in terms of handover delay while maintaining minimal signaling overhead in the air interface among converged heterogeneous wireless networks. The handover signaling procedures with host-based MIPv6 are compared with network-based proxy MIPv6 (PMIPv6) and fast PMIPv6 assisted by G-MAG to show how much handover delay reduction can be achieved. Analytical results show that the handover delay is significantly reduced.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.6
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• pp.1157-1169
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• 2021

The disaster recovery refers to policies and procedures to ensure continuity of services and minimize loss of resources and finances in case of emergency situations such as natural disasters. In particular, the disaster recovery method by the cloud service provider has advantages such as management flexibility, high availability, and cost effectiveness. However, this method has a dependency on a service provider and has a structural limitation in which a user cannot be involved in personal data. In this paper, we propose a protocol using proxy re-encryption for data confidentiality by removing dependency on service providers by backing up user data using blockchain and distributed storage. The proposed method is implemented in Ethereum and IPFS environments, and presents the performance and cost required for backup and recovery operations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.747-754
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• 1999

Mobile Agent is a movable software program that autonomously runs on behalf of its operator in a network environment. It has been widely applied to various kinds of computer engineering. In this paper, a network management architecture using the mobile agent technology in the distributed network environment is proposed. After manager system creates the mobile agent, it searches a proxy, a distributed object that acts as the substitute for a SNMP agent. In order to get the management information that manager requires, the mobile agent goes to the proxy and does operations on it. So, only the concise results from the operation are sent to the managing system. The proposed architecture is based on CORBA that provides several transparent characteristics in the distributed environment. In additional, the proxy object that represents the SNMP agent enables the mobile agent and the SNMP agent to converse with themselves. In this architecture, the mobile agent can carry out an automated management function, easily change and modify management functions. Therefore, it can provide an efficient management way.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.9
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• pp.435-444
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• 2007

Caching web pages is an important part of web infrastructures. The effects of caching service are even more pronounced for wireless infrastructures due to their limited bandwidth. Medium to large-scale infrastructures deploy a cluster of servers to solve the scalability problem and hot spot problem inherent in caching. In this paper we present scheduling scheme based on cache utilization in a wireless internet proxy server cluster environment. The proposed method uses cache utilization for distributing evenly client requests to a cluster of cache servers and solving hot spot problem. We have implemented our approach and performed various experiments using publicly available traces. Experimental results on a cluster of 16 cache servers demonstrate that the proposed hashing method gives 45% to 114% Performance improvement over other widely used methods while addressing the hot spot problem.

• Convergence Security Journal
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• v.11 no.6
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• pp.9-15
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• 2011

It is difficult to identify attack requests from normal ones when those attacks are based on CSRF which enables an attacker transmit fabricated requests of a trusted user to the website. For the protection against the CSRF, there have been a lot of research efforts including secret token, custom header, proxy, policy model, CAPTCHA, and user reauthentication. There remains, however, incapacitating means and CAPTCHA and user reauthentication incur user inconvenience. In this paper, we propose a method to detect CSRF attacks by analyzing the structure of websites and the usage patterns. Potential victim candidates are selected and website usage patterns according to the structure and usage logs are analyzed. CSRF attacks can be detected by identifying normal usage patterns. Also, the proposed method does not damage users' convenience not like CAPTCHA by requiring user intervention only in case of detecting abnormal requests.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.758-766
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• 2007

IStreaming services with a client-server architecture have scalability problem because a server cannot accomodate clients more than its processing capability. This paper introduces a case study for implementing H.264 streaming system based on P2P architecture in order to provide scalable and stable broadcast streaming services over the internet. The prototype system called OmniCast264 consists of the H.264 encoding server, the streaming server, the proxy server, and peer nodes. The proxy server dynamically manages placement of the peer nodes on the P2P network. Omnicast264 has the concepts of distributed streaming loads, real-time playback, error-robustness and modularity. Thus, it can provide large-scale broadcast streaming services. Finally, we have built P2P streaming systems with 12 PCs connected serially or in parallel. The experiment shows that OmniCast264 can provide real-time playback.