• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.298-305
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• 2003

In this paper, we proposed a high performance lookup controller for IP packet forwarding engine of ATM based label edge routers. The lookup controller is designed to provide services such as MPLS, VPN, ELL, and RT services as well as the best effort. For high speed searching for IP addresses, we employed a TCAM based hardware search device not using traditional algorithmic approaches. We also implement lookup control functions into FPGA for fast processing of packet header and lookup control. The proposed lookup controller is designed to support differenciated services for users and to process in pipelined mechanism for performance improvement. A two-step search scheme is also applied to perform lookup for the key combined with multi-field of packet header. We found that the proposed lookup controller provides the performance of about 16M packets per second through simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.268-274
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• 2008

With the advances in wireless communication technologies, mobile users require to get seamless services anywhere and anytime. To relize these demands, network interworking and vertical handover are necessary between heterogeneous wireless access technologies with multi-interface mobile station. A lot of organizations are doing research on the network integration schemes based on loosely and tightly integrated architectures, and research on vertical handover schemes mainly based on Mobile IP in loosely integrated environments. But actually, the tightly integrated scheme can support more faster vertical handover because heterogeneous access networks are combined tightly. However, vertical handover schemes in tightly integrated environments are conceptually proposed without any detail signaling procedures. Therefore, this paper defines a tightly integrated architecture between UMTS and WLAN, and proposes a soft vertical handover signaling procedure. The proposed soft vertical handover scheme is evaluated by the OPNET simulator, and we confirm the proposed scheme can support seamless services.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.407-412
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• 2004

The e-learning system uses multimedia content for efficiency of a education and learner's convenience. With the web based e-learning, various multimedia services are difficult on account of physical factors such as network state and system performance. Also on the off line based e-learning, we have defects an insufficiency of interactions among learners and instructors, and an insufficiency of an adaptation about the latest information. In this study, we designed a multi-tier e-learning system using hybrid multimedia method, The proposed system can provide interaction and adaptability such as web based systems, and it can provide various multimedia content such as off line based systems. In experiments results, we know the proposed system improved users' convenience and an adaptability about the latest information, and interactions among learners and instructors when compare with existing e-learning system.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.1-9
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• 2013

In recent, the cloud computing makes it possible to provide the on-demand provision of software, hardware, and data as a service in various IT fields. This paper uses the cloud computing techniques for the real time broadcasting service of virtual 3D contents. However, the existing related solutions have many problems that the load of the server is rapidly increased or the cost of the server is very high when the number of service users is increased. Therefore, we propose a new application virtualization method to solve these problems. It promises their stable operations in multi-user services because the proposed method does not execute the rendering commands of the application at the host server but delivers and executes them to clients via the Internet. Our performance experiments show that our proposed method outperforms the existing methods.

• Journal of the Korean Society for information Management
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• v.27 no.4
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• pp.193-217
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• 2010

With the advent of uniquitous life, changes of users' demands make a public library accomplish roles and functions of a complex service center providing information, education and culture service. As a multi-function center, a public library provides various services based on physical and digital space in ubiquitous environment. Information commons is a basement of physical space in an u-Library. Especially, with the advent of ubiquitous environment, design and use of physical space will be a critical issue for a public library to perform its role and function as a multiple complicated space. This study derives facilities and components for designing and implementing information commons in a public library as a physical space. To perform the goals, this study focuses on the newest trends and requirements through literature study, case study and survey. As a result, this study proposes components of facility and principles of design to implement information commons as a physical space in a public library.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.372-382
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• 2005

DS/CDM-QPSK (ITU-R Recommendation BO.1130-4 Annex 6, 'Digital System E'), which has been adoptedas a standard of Korean Satellite DMB (Digital Multimedia Broadcasting) system, is a satellite-based multimedia broadcasting service which transmits the multi-channel and high quality contents to the terrestrial users through a satellite or gap-fillers. The broadcast from a satellite is directly received in the plain terrain which are within line-of-sight, but in cities where the broadcast cannot be received directly due to the shadow of buildings, an attempt is being made to install 'Gap-Fillers' to improve the reception in those areas. The gap-fillers, however, may induce interference to service of adjacent band, when their output power is substantially higher compared to the received signal power of signal from a satellite of the adjacent service. In this paper, a link budget analysis is performed, and the optimal EIRP of a gap-filler to maximize the gap-filler coverage, while preventing adjacent band interference is derived.

• Journal of KIISE
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• v.43 no.7
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• pp.781-785
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• 2016

Learning from human behaviors in the real world is essential for human-aware intelligent systems such as smart assistants and autonomous robots. Most of research focuses on correlations between sensory patterns and a label for each activity. However, human activity is a combination of several event contexts and is a narrative story in and of itself. We propose a novel approach of human activity prediction based on event cognition. Egocentric multi-sensor data are collected from an individual's daily life by using a wearable device and smartphone. Event contexts about location, scene and activities are then recognized, and finally the users" daily activities are predicted from a decision rule based on the event contexts. The proposed method has been evaluated on a wearable sensor data collected from the real world over 2 weeks by 2 people. Experimental results showed improved recognition accuracies when using the proposed method comparing to results directly using sensory features.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.5
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• pp.533-542
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• 1999

웹은 지금까지의 문자 위주의 응용에서 벗어나, 그림, 동영상과 같은 멀티미디어 자료를 브라우저를 통해 접근할 수 있도록 하여, 점차 많은 응용분야에서 사용되고 있다. 최근에 들어서는 데이타베이스와 웹의 연동을 통해, 보다 다양하고, 양질의 웹 서비스를 지원하고자 하는 노력으로, 많은 연구자들이 웹 통로에 대한 많은 연구로 좋은 결과를 내고 있다. 그러나 웹과 데이타베이스의 연동에 있어 필요한 웹 트랜잭션 처리시 발생하는 문제에 있어서는 아직까지 만족할 만한 연구결과가 제시되지 않고 있다.본 논문에서는 웹 통로에서 웹 트랜잭션 처리를 위한 시스템인 WebTP를 제안하고, 이를 구현하였다. WebTP는 워크, 워크-전역변수 등을 도입하여, 웹 응용 단위에서의 저장점 설치와 부분 철회와 트랜잭션 상태 관리 기법을 제공하여, 시스템의 가용성과 안정성을 높이며, 구조적인 웹 응용작성이 가능토록 하여, 복잡한 웹 응용 개발을 돕는다.Abstract Enabling users to access multi-media data like images and motion pictures, in addition to the traditional text-based data, Web becomes a popular platform for various applications. Recently, many researchers have paid a large amount of works on integrating Web and databases to improve the quality of Web services, and have produced many noticeable results on this area. However, no enough research results have been presented on processing Web transactions that are essential in integrating Web and databases.In this paper, we have designed and implemented WebTP, which is a Web transaction processing system for Web gateways to databases. WebTP, by introducing work and work-global-variables, provides a more robust state management, supports application-level savepoints and partial rollbacks. It also nhances productity by providing a modular way to develop Web applications.

• The KIPS Transactions:PartA
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• v.16A no.2
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• pp.135-142
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• 2009

With the development of ubiquitous computing technology, the number of HCI applications is increasing, where they utilize various contexts to provide adaptive services to users according to the change of contexts, and also, technologies for collecting various sensor data and generating integrated contexts get more important. However, the research on the collection and integration of multi-sensor data is not sufficient when we consider the various utilization areas of the integrated contexts. In particular, they have some problems to be solved such as duplication of the context data and the high system load. In this paper, we propose an integrated context generation scheme based on Ant Colony System. Proposed scheme generates the context data as a form of XML and avoids the generation of unnecessary context information by detecting the repeated sensor information based on the ant colony system. As a result of detections, we reduce wasted resources and repositories when the integrated context is created. We also reduce the overhead for reasoning.

• The KIPS Transactions:PartD
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• v.15D no.5
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• pp.721-732
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• 2008

The purpose of this study is to explore latent variables that affect users' satisfaction of mobile internet and to estimate a composite relationships among parameters. In order to examine causative significance between dependent variables and each of the independent variables, we redefined the variables, the quality of information, system and service derived from the DeLone and McLean's model. And we found out the new independent variables: security and service charge. Prior research adopted mainly TAM(Technology Acceptance Model) to investigate the user acceptance of information services or system. Therefore, it is significant that we developed our research model to appropriate on mobile internet's inherent nature and that focused on the important variables like service charge and security. In empirical approach, we surveyed 435 samples and conducted structural equation modeling and multi-regression analysis to estimate the regression parameters. The results of the study illustrated that our hypotheses covering the quality of information, system and service, security and service charge were supported.