• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.5A
• /
• pp.751-762
• /
• 2000

In the forthcoming next generation highspeed networks, the provisioning of broadband mobile multimedia services is the most important issue while an efficient network management architecture, which can manage the network resources efficiently, is essential. The next generation highspeed networks will be composed of the ATMand SDH-based transport network systems and the H-based interworking systems. The management functions of these network systems are implemented various technologies, such as TMN and SNMP. In order to integrate these network resources efficiently with heterogeneous management functions, the distributed network management architecture such as TINA is most appropriate. In this pape, we propose an interworking architecture for TINA manager and TMN agent. where the TINA-based EML subnetwork management operations mapped into the related management operations of the TMN NE agent. The proposed interworking architecture is simpler than JIDM, and the processing overhead is minimized.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.12
• /
• pp.3118-3134
• /
• 2013

This paper deliberates for a multimedia transmission scheme combining multiple description coding (MDC) and network coding (NC). Our goal is to take advantage from the property of MDC to provide quantized and compressed independent and identically distributed (iid) descriptions and also from the benefit of network coding, which uses network resources efficiently to recover lost data in the network. Recently, p-cycle NC has been introduced to recover and protect any lost or distorted descriptions at the receiver part exactly without need of retransmission. So far, MDC have not been explored using this type of NC. Compressed and coded descriptions are transmitted through the network where p-cycle NC is applied. P-cycle based algorithm is proposed for single and multiple descriptions lost. Results show that in the fixed bit rate, the PSNR (Peak Signal to Noise Ratio) of our reconstructed image and also subjective evaluation is improved significantly compared to previous work which is averaging method joint with MDC in order to conceal lost descriptions.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.5
• /
• pp.691-708
• /
• 2010

An important issue of supporting multi-users with diverse quality-of-service (QoS) requirements over wireless networks is how to optimize the systematic scheduling by intelligently utilizing the available network resource while, at the same time, to meet each communication service QoS requirement. In this work, we study the problem of a variety of communication services over multi-media heterogeneous cognitive OFDM system. We first divide the communication services into two parts. Multimedia applications such as broadband voice transmission and real-time video streaming are very delay-sensitive (DS) and need guaranteed throughput. On the other side, services like file transmission and email service are relatively delay tolerant (DT) so varying-rate transmission is acceptable. Then, we formulate the scheduling as a convex optimization problem, and propose low complexity distributed solutions by jointly considering channel assignment, bit allocation, and power allocation. Unlike prior works that do not care computational complexity. Furthermore, we propose the FAASA (Fairness Assured Adaptive Sub-carrier Allocation) algorithm for both DS and DT users, which is a dynamic sub-carrier allocation algorithm in order to maximize throughput while taking into account fairness. We provide extensive simulation results which demonstrate the effectiveness of our proposed schemes.

• Journal of Information Processing Systems
• /
• v.13 no.6
• /
• pp.1544-1553
• /
• 2017

The network coding mechanism has attracted much attention because of its advantage of enhanced network throughput which is a desirable characteristic especially in a multi-hop wireless network with limited link capacity such as the device-to-device (D2D) communication network of 5G. COPE proposes to use the XOR-based network coding in the two-hop wireless network topology. For multi-hop wireless networks, the Distributed Coding-Aware Routing (DCAR) mechanism was proposed, in which the coding conditions for two flows intersecting at an intermediate node are defined and the routing metric to improve the coding opportunity by preferring those routes with longer queues is designed. Because the routes with longer queues may increase the delay, DCAR is inefficient in delivering real-time multimedia traffic flows. In this paper, we propose a network coding-aware routing protocol for multi-hop wireless networks that enhances DCAR by considering traffic load distribution and link quality. From this, we can achieve higher network throughput and lower end-to-end delay at the same time for the proper delivery of time-sensitive data flow. The Qualnet-based simulation results show that our proposed scheme outperforms DCAR in terms of throughput and delay.

• Annual Conference of KIPS
• /
• 2001.04a
• /
• pp.101-104
• /
• 2001

데이터베이스에서 트랜잭션의 처리량을 향상시키기 위해서 기존의 문법 위주의 직렬성 이론으로는 단위시간당 처리량을 높이기는 힘든 형편이다. 이를 위하여 이타적 잠금 기법(altruistic locking: AL)은 트랜잭션이 객체를 사용한 다음 더 이상 그 객체를 요구하지 않을 때 다른 트랜잭션들이 그 객체를 로크할 수 있도록 미리 객체에 대한 로크를 해제함으로써 트랜잭션들의 대기시간을 줄이고 처리량을 향상시키기 위한 취지에서 제안된 것이다. 확장형 이타적 잠금(extended altruistic locking: XAL)기법은 AL 을 자취의 확장한 것으로 AL 이 근본적으로 안고 있는 반드시 기부된 객체만을 처리해야 한다는 제약을 완화한 기법이다. 본 논문에서는 분산 데이터베이스 환경하에서 장기 트랜잭션으로 인한 단기 트랜잭션의 대기현상을 최소화하도록 함으로써 동시성 제어의 정도를 높일 수 있는 새로운 확장형 이타적 잠금 기법인 양방향 기부기법(two-way donation locking: 2DL)을 제안하고 기존의 제어기법과 비교하였다. 모의실험에 의한 성능평가 결과 2DL 은 작업 처리율과 트랜잭션의 평균 대기시간 면에서 우수한 결과를 나타내었다.

• Journal of Engineering Education Research
• /
• v.10 no.3
• /
• pp.79-92
• /
• 2007

To enhance the excellence, effectiveness and economical efficiency in the learning process, we implement a hybrid educational system for engineering experiments where web-based virtual laboratory systems and distance education systems are properly integrated. In the first stage, we designed client/server distributed environment and developed web-based virtual laboratory systems for digital systems and electrical/electronic circuit experiments. The proposed virtual laboratory systems are composed of four important sessions and their management system: concept learning session, virtual experiment session, assessment session. With the aid of the management system every session is organically tied up together to achieve maximum learning efficiency. In the second stage, we have implemented efficient and cost-effective distant laboratory systems for practicing electric/electronic circuits, which can be used to eliminate the lack of reality occurred during virtual laboratory session. The use of simple and user-friendly design allows a large number of people to access our distant laboratory systems easily. Thus, self-guided advanced training is available even if a lot of expensive equipment will not be provided in the on-campus laboratories. The proposed virtual/distant laboratory systems can be used in stand-alone fashion, but to enhance learning efficiency we integrated them and developed a hybrid educational system for engineering experiments. Our hybrid education system provides the learners with interactive learning environment and a new approach for the delivery of engineering experiments.

• Journal of Information Processing Systems
• /
• v.3 no.2
• /
• pp.43-53
• /
• 2007

The use of agent paradigm in today's applications is hampered by the security concerns of agents and hosts alike. The agents require the presence of a secure and trusted execution environment; while hosts aim at preventing the execution of potentially malicious code. In general, hosts support the migration of agents through the provision of an agent server and managing the activities of arriving agents on the host. Numerous studies have been conducted to address the security concerns present in the mobile agent paradigm with a strong focus on the theoretical aspect of the problem. Various proposals in Intrusion Detection Systems aim at securing hosts in traditional client-server execution environments. The use of such proposals to address the security of agent hosts is not desirable since migrating agents typically execute on hosts as a separate thread of the agent server process. Agent servers are open to the execution of virtually any migrating agent; thus the intent or tasks of such agents cannot be known a priori. It is also conceivable that migrating agents may wish to hide their intentions from agent servers. In light of these observations, this work attempts to bridge the gap from theory to practice by analyzing the security mechanisms available in Aglet. We lay the foundation for implementation of application specific protocols dotted with access control, secured communication and ability to detect tampering of agent data. As agents exists in a distributed environment, our proposal also introduces a novel security framework to address the security concerns of hosts through collaboration and pattern matching even in the presence of differing views of the system. The introduced framework has been implemented on the Aglet platform and evaluated in terms of accuracy, false positive, and false negative rates along with its performance strain on the system.

• Journal of KIISE:Computing Practices and Letters
• /
• v.11 no.4
• /
• pp.334-348
• /
• 2005

The goal of next generation digital broadcasting is offering the interaction among consumers and providers as well as variety services. One of the important factors for this new broadcasting environment keeps the interoperability among providers and consumers since the environment is distributed. Therefore a standard metadata for digital broadcasting is required and TV-Anytime metadata is one of the metadata standards for digital broadcasting. The terminal nodes of TV-Anytime metadata are defined by using MPEG-7 metadata. MPEG-7 metadata is standard metadata for describing multimedia content. Therefore, if we use the MPEG-7 metadata for describing broadcasting content can offer multimedia search services like content-based search by the extension of metadata. The efficient management system for these metadata is important for offering the services with high Duality on real broadcasting environment TV-Anytime metadata and MPEG-7 metadata are technically defined using a single XML schema, so its instances are XML data. Currently, a lot of systemsfor managing XML data are proposed in many researchers and we can expect to adapt these systems for managing broadcasting metadata. But the methods used in these systems are not specific methods for managing broadcasting metadata because of methods for general-purpose. In this paper, we find the properties of broadcasting metadata and develop an efficient metadata management system that is based on the found properties. Since our systemis implemented on real broadcasting environment, we expect that the system is most efficient and suitable. Also our system is interoperable since we use XQuery as query language for querying broadcasting metadata.

• The KIPS Transactions:PartD
• /
• v.14D no.5
• /
• pp.555-564
• /
• 2007

Internet streaming systems consist of a media server, a streaming sewer, and terminals. The media server delivers multimedia contents such as video and/or audio to the streaming server, which distributes the contents to terminals as well. Existing Internet streaming systems have a bottleneck problem in the streaming server because of the limit of the processing capacity of the streaming server and therefore a streaming server can not accomodate more terminals than the limit. As a solution to this problem, P2P streaming systems have been lately proposed and investigated, using P2P distributed architectures. Actually, however, there exist many difficulties in the design and implementation of P2P streaming systems, because it needs many real computers and various network constructions. In this paper, we have proposed and defined a P2P streaming system model such as the architectural model, the timing model, the behavior model, and the performance metrics. And also we have implemented an NS2 based P2P streaming system simulator called P2PStreamSim. Finally, we have verified it through test simulations and analyzed the results.

• Journal of Internet Computing and Services
• /
• v.14 no.6
• /
• pp.71-84
• /
• 2013

Log data, which record the multitude of information created when operating computer systems, are utilized in many processes, from carrying out computer system inspection and process optimization to providing customized user optimization. In this paper, we propose a MongoDB-based unstructured log processing system in a cloud environment for processing the massive amount of log data of banks. Most of the log data generated during banking operations come from handling a client's business. Therefore, in order to gather, store, categorize, and analyze the log data generated while processing the client's business, a separate log data processing system needs to be established. However, the realization of flexible storage expansion functions for processing a massive amount of unstructured log data and executing a considerable number of functions to categorize and analyze the stored unstructured log data is difficult in existing computer environments. Thus, in this study, we use cloud computing technology to realize a cloud-based log data processing system for processing unstructured log data that are difficult to process using the existing computing infrastructure's analysis tools and management system. The proposed system uses the IaaS (Infrastructure as a Service) cloud environment to provide a flexible expansion of computing resources and includes the ability to flexibly expand resources such as storage space and memory under conditions such as extended storage or rapid increase in log data. Moreover, to overcome the processing limits of the existing analysis tool when a real-time analysis of the aggregated unstructured log data is required, the proposed system includes a Hadoop-based analysis module for quick and reliable parallel-distributed processing of the massive amount of log data. Furthermore, because the HDFS (Hadoop Distributed File System) stores data by generating copies of the block units of the aggregated log data, the proposed system offers automatic restore functions for the system to continually operate after it recovers from a malfunction. Finally, by establishing a distributed database using the NoSQL-based Mongo DB, the proposed system provides methods of effectively processing unstructured log data. Relational databases such as the MySQL databases have complex schemas that are inappropriate for processing unstructured log data. Further, strict schemas like those of relational databases cannot expand nodes in the case wherein the stored data are distributed to various nodes when the amount of data rapidly increases. NoSQL does not provide the complex computations that relational databases may provide but can easily expand the database through node dispersion when the amount of data increases rapidly; it is a non-relational database with an appropriate structure for processing unstructured data. The data models of the NoSQL are usually classified as Key-Value, column-oriented, and document-oriented types. Of these, the representative document-oriented data model, MongoDB, which has a free schema structure, is used in the proposed system. MongoDB is introduced to the proposed system because it makes it easy to process unstructured log data through a flexible schema structure, facilitates flexible node expansion when the amount of data is rapidly increasing, and provides an Auto-Sharding function that automatically expands storage. The proposed system is composed of a log collector module, a log graph generator module, a MongoDB module, a Hadoop-based analysis module, and a MySQL module. When the log data generated over the entire client business process of each bank are sent to the cloud server, the log collector module collects and classifies data according to the type of log data and distributes it to the MongoDB module and the MySQL module. The log graph generator module generates the results of the log analysis of the MongoDB module, Hadoop-based analysis module, and the MySQL module per analysis time and type of the aggregated log data, and provides them to the user through a web interface. Log data that require a real-time log data analysis are stored in the MySQL module and provided real-time by the log graph generator module. The aggregated log data per unit time are stored in the MongoDB module and plotted in a graph according to the user's various analysis conditions. The aggregated log data in the MongoDB module are parallel-distributed and processed by the Hadoop-based analysis module. A comparative evaluation is carried out against a log data processing system that uses only MySQL for inserting log data and estimating query performance; this evaluation proves the proposed system's superiority. Moreover, an optimal chunk size is confirmed through the log data insert performance evaluation of MongoDB for various chunk sizes.