• 정보처리학회논문지C
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• 제9C권6호
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• pp.953-960
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• 2002

실시간 응용 프로그램은 미디어 데이터간에 만족되어야 할 동기화 제약조건(synchronization constraints)을 가지고 있다. 멀티미디어 데이터의 가변적 전송 시연 시간을 흡수하여 피드백 제어와 재생정책에 의한 동기화 기법을 수행한다. 버퍼의 수위가 정상레벨을 유지하는가에 대한 문제는 재생률과 QoS 서비스에 중요한 영향을 주게 된다. 본 논문에서는 버퍼의 수위를 안정상태고 유지하기 위해 피트백을 위한 필터링함수를 적용하고, 재생시간을 적응적으로 적용하여 미디어의 재생 시 끊어짐이 없는 유연한 재생을 한다. 또한 버퍼의 주 미디어인 오디오 프레임의 버퍼가 상위임계레벨에 수위가 존재 할 경우는 적응적으로 재생시간을 줄이고, 하위임계레벨에 버퍼의 수위가 있을 경우는 점차적으로 재생시간을 늘리는 시스템이다.

• 한국IT서비스학회지
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• 제8권1호
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• pp.193-202
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• 2009

Cloud computing emerges as a new computing paradigm which targets reliable and customizable services. The term builds on decades of research in virtual machine, distributed and parallel computing, utility computing, and more recently networking, web service, and software as a service. In this paper, we provide a seamless connection migration of web services. This is useful for cloud computing environment in which many client terminals have mobility. With the wireless internet facility, those mobile users can move place to place during internet communication. Therefore, we provide solutions to the two major problems in current virtualization based migration: communication failure problems and connection re-establishment. Communication channel flushing by zero window notification helps to resolve the communication failure problems and TCP port inheritance prevents connection re-establishment errors during socket reconstruction. Thus, our web service migration facility is now able to preserve open network connections, and even for server sockets. This is a highly transparent approach, in that we did not Introduce additional messages for channel flushing and did not make any modification to the TCP protocol stack. Experimental results show that the overhead due to connection migration of web services is almost negligible when compared with time to take the conventional web service migration.

• 정보처리학회논문지B
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• 제9B권5호
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• pp.517-522
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• 2002

이동 에이전트 시스템은 기존 클라이언트-서버 모델이 가진 제한 사항을 해결하고, 네트워크 환경의 보다 효율적인 활용을 가능하게 하는 방안 중 하나로 제안되었다. 이동 에이전트 시스템은 네트워크 상의 이질적인 호스트 환경에서 원활히 동작할 수 있는 인터페이스를 제공하는 시스템이며, 신뢰성 있는 실행을 위하여 이동 에이전트를 구현하는 이동 코드에서의 보안 문제 해결이 선행되어야 한다. 본 논문에서는 이동 에이전트가 에이전트 소유자의 요구에 따라 네트워크 상을 이동하여 실행될 때, 각각의 호스트에서 수행된 결과 값에 서명 기법과 해쉬 체인 기법을 적용하여 전방향 무결성, 부인 방지, 부정 검출을 가능하게 하는 프로토콜을 제안한다.

• Journal of Information Processing Systems
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• 제1권1호
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• pp.62-69
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• 2005

This paper presents a queuing analysis model of a PC-based software router supporting IPv6-IPv4 translation for residential gateway. The proposed models are M/G/1/K or MMPP-2/G/1/K by arrival process of the software PC router. M/G/1/K is a model of normal traffic and MMPP-2/G/1/K is a model of burst traffic. In M/G/1/K, the arriving process is assumed to be a Poisson process, which is independent and identically distributed. In MMPP-2/G/1/K, the arriving process is assumed to be two-state Markov Modulated Poisson Process (MMPP) which is changed from one state to another state with intensity. The service time distribution is general distribution and the service discipline of the server is processor sharing. Also, the total number of packets that can be processed at one time is limited to K. We obtain performance metrics of PC-based software router for residential gateway such as system sojourn time blocking probability and throughput based on the proposed model. Compared to other models, our model is simpler and it is easier to estimate model parameters. Validation results show that the model estimates the performance of the target system.

• 전기학회논문지
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• 제65권2호
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• pp.354-359
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• 2016

Power plants maintenance data is to be sent to management server system via a communication network. In this case, reliable communication network is required. Transmission of the power plants maintenance data is used in the wired communication network or wireless communication network. PLC communication network is a kind of wired communication network. However PLC communication network is easily affected by noise. On the vulnerable areas in power line system, such as a mountain or rural areas, it is difficult to form a power line communication network. For a wireless communication, environment are also influenced factors in wireless communication. Harsh environmental factors are bring the communication characteristic degradation. In such areas it can be used a combination of two networks and in this way the complementary function can be achieved. Power plants are distributed in various regions across the country. The appropriate communication network is needed to maintain the power plant.This study investigated the effect of environment on the wired communication and wireless communication. It would examine a variable factor which is affect to the communication characteristic. We used PLC communication for wired communication network and ZigBee communication for wireless communication network. We investigated the characteristics of a single communication network and it raised the need for a complex communication technology to complement a single communication network.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.588-591
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• 2009

유비쿼터스 컴퓨팅 환경의 GIS 서비스는 모바일 기기를 이용하여 언제 어디서나 공간데이터를 이용할 수 있다. GIS 서비스는 최적의 서비스를 제공하기 위해 주기적으로 공간데이터를 최신의 데이터로 갱신한다. 모바일 환경에서는 이를 위해 변경데이터를 CD로 배포하거나 유선 네트워크를 이용한 업데이트 서비스를 제공한다. 그러나 이러한 배포방식은 실제 세계의 변경이 사용자에게 전달되기까지 오랜 시간이 소모되는 문제가 있다. 이 논문에서는 사용자까지 변경 데이터가 도달하는 시간을 최소화 하기위한 동기화 시스템을 제안한다. 이 동기화 시스템은 모바일 기기를 이용하여 현장에서 변경된 데이터를 수집하고, 수집된 데이터를 무선네트워크를 이용하여 실시간으로 서버와 동기화한다. 이를 위하여 무선 네트워크 모듈과 변경 데이터를 갱신하는 동기화 모듈을 설계 및 구현하였다.

• 한국멀티미디어학회논문지
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• 제22권4호
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• pp.463-471
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• 2019

The growth of mobile technology particularly smartphone applications such as ticketing, access control, and making payments are on the increase. Elliptic Curve Cryptography (ECC)-based systems have also become widely available in the market offering various convenient services by bringing smartphones in proximity to ECC-enabled objects. When a system user attempts to establish a connection, the AIK sends hashes to a server that then verifies the values. ECC can be used with various operating systems in conjunction with other technologies such as biometric verification systems, smart cards, anti-virus programs, and firewalls. The use of Elliptic-curve cryptography ensures efficient verification and signing of security status verification reports which allows the system to take advantage of Trusted Computing Technologies. This paper proposes a device payment method based on ECC and Shuffling based on distributed key exchange. Our study focuses on the secure and efficient implementation of ECC in payment device. This novel approach is well secure against intruders and will prevent the unauthorized extraction of information from communication. It converts plaintext into ASCII value that leads to the point of curve, then after, it performs shuffling to encrypt and decrypt the data to generate secret shared key used by both sender and receiver.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.668-685
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• 2019

Provision of higher throughput without sacrificing consistency guarantees in replication systems is a critical problem. In this paper, we propose a novel approach called Bidirectional Chain Replication (BCR) to improve throughput in traditional Chain Replication (CR) through better utilization of computing and communication resources of the chain. Unlike CR where the whole replicated data store is treated as a single unit, in BCR the replicated shared data at each server in the chain is split into two disjoint Logical Partitions ($LP_1$, $LP_2$). This forms two chains running concurrently on the same hardware in two opposite directions; the first chain ($CR_1$) exclusively manipulates data objects in $LP_1$, while the second chain ($CR_2$) exclusively manipulates data objects in $LP_2$, therefore, conflict is avoided and concurrency is guaranteed. The simultaneous employment of these two chains results in better utilization of hardware in the sense that the two chains can evenly share the workload, hence, throughput can be improved without sacrificing consistency. Experimental results showed an improvement of approximately 85% in throughput of BCR over CR.

• International Journal of Computer Science & Network Security
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• 제21권9호
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• pp.1-10
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• 2021

The Internet of things (IoT) is the main advancement in data processing and communication technologies. In IoT, intelligent devices play an exciting role in wireless communication. Although, sensor nodes are low-cost devices for communication and data gathering. However, sensor nodes are more vulnerable to different security threats because these nodes have continuous access to the internet. Therefore, the multiparty security credential-based key generation mechanism provides effective security against several attacks. The key generation-based methods are implemented at sensor nodes, edge nodes, and also at server nodes for secure communication. The main challenging issue in a collaborative key generation scheme is the extensive multiplication. When the number of parties increased the multiplications are more complex. Thus, the computational cost of batch key and multiparty key-based schemes is high. This paper presents a Secure Multipart Key Distribution scheme (SMKD) that provides secure communication among the nodes by generating a multiparty secure key for communication. In this paper, we provide node authentication and session key generation mechanism among mobile nodes, head nodes, and trusted servers. We analyzed the achievements of the SMKD scheme against SPPDA, PPDAS, and PFDA schemes. Thus, the simulation environment is established by employing an NS 2. Simulation results prove that the performance of SMKD is better in terms of communication cost, computational cost, and energy consumption.

• International Journal of Internet, Broadcasting and Communication
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• 제13권1호
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• pp.201-209
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• 2021

The term, eGovernmen or e-Government, uses technology communications devices such as computers and the Internet to provide public services to citizens and others. The eGovernment or e-government provides citizens with new opportunities to access the government directly and conveniently, while the government provides citizens with directservices. Also, in these days, cloud computing is a feature that enables users to use computer system resources, especially data storage (cloud storage) and on-demand computing power, without having to manage themselves. The term is commonly used to describe data centers that are available to many users over the Internet. Today, the dominant Big Cloud is distributed across multiple central servers. You can designate it as an Edge server if it is relatively close to the user. However, despite the prevalence of e-government and cloud computing, each of these concepts has evolved. Research attempts to combine these two concepts were not being made properly. For this reason, in this work, we aim to produce independent and objective analysis results by separating progress steps for the analysis of e-government cloud service platforms. This work will be done through an analysis of the development process and architectural composition of the e-government development standard framework and the cloud platform PaaS-TA. In addition, this study is expected to derive implications from an analysis perspective on the direction and service composition of the e-government cloud service platform currently being pursued.