• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.393-395
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• 2011

본 논문에서는 모바일 통신 방송 융합분야는 세계 각국이 서로 상이한 표준을 가지고 있어 해외 시장 진출 시 제품 신뢰성 확보를 위한 해외 현지에서의 테스트가 중요시 되어서 국내 기업의 테스트 비용과 개발기간 면에서 경쟁력 확보의 악재로 작용하고 있다. 따라서 모바일 통신 방송의 세게 각 국 표준의 테스트 인프라를 확보하고 이를 활용하는 테스트의 전반적인 시스템을 구축하여 국내 기업의 테스트 비용 절감 및 개발기간 단축과 다양한 서비스 개발이 가능하다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1371-1379
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• 1992

In this paper, we describe the general concept of digital mobile communications system and present a client-server model for the implementation of roaming function, which is on of the most important functions in digital mobile communications system. And finally we also describe our simulation test and analysis for the presented client-server model.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.493-498
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• 2008

We proposed "Table Mediator" which is a tabletop system for digital storytelling that uses web-retrieved information for the students' educational field trip. Students can perform their storytelling for their virtual pre-field trip to build up a sequential path as a story with web-retrieved documents, satellite images, geographical information, and group discussion. The proposed system was designed to lessen the limitation of individual interaction such as restricted viewpoint and biased inclination by group digital storytelling. Local interactions also have the limitation such as insufficient information and knowledge and the system supplied the rich live information such as subjective critiques or recently discovered history, or new updates for building a story that makes users arrange their own idea as a consistent story to lessen the limitation of the local interactions. The system can be used for various applications such as travel, education and other collaborative works with group interaction.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.43-46
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• 2004

MPEG-21 is an on-progress project of the Moving Picture Expert Group (MPEG) that has been started in many independent parts such as part for standardizing the declaration of a digital item (MPEG-21 Part 2: Digital Item Declaration), right expression language (MPEG-21 Part S: Rights Expression Language), way to process the digital item (MPEG-21 Part 10: Digital Item Processing), etc. All this part is intended to form a framework to enable transparent and augmented use of multimedia resources across a wide range of networks and devices (1). In this paper, we show our research initiative to develop a web-based application that utilized many parts of MPEG-21 technology. The implemented concept uses a digital item and license providers in the server side while the MPEG-21 Conformant application is implemented as a plug-in application that will be downloaded to the user terminal when user accesses the webpage for the frist time. The result of this research shows that with some combination of MPEG-21 parts, we can develop an authorized multimedia delivery and consumption application.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.364-374
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• 2016

With vast amounts of spectrum available in the millimeter wave (mmWave) band, small cells at mmWave frequencies densely deployed underlying the conventional homogeneous macrocell network have gained considerable interest from academia, industry, and standards bodies. Due to high propagation loss at higher frequencies, mmWave communications are inherently directional, and concurrent transmissions (spatial reuse) under low inter-link interference can be enabled to significantly improve network capacity. On the other hand, mmWave links are easily blocked by obstacles such as human body and furniture. In this paper, we develop a multi-hop relaying transmission (MHRT) scheme to steer blocked flows around obstacles by establishing multi-hop relay paths. In MHRT, a relay path selection algorithm is proposed to establish relay paths for blocked flows for better use of concurrent transmissions. After relay path selection, we use a multi-hop transmission scheduling algorithm to compute near-optimal schedules by fully exploiting the spatial reuse. Through extensive simulations under various traffic patterns and channel conditions, we demonstrate MHRT achieves superior performance in terms of network throughput and connection robustness compared with other existing protocols, especially under serious blockage conditions. The performance ofMHRT with different hop limitations is also simulated and analyzed for a better choice of the maximum hop number in practice.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.115-119
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• 2007

Huge amount of useful information is getting added to the academic digital world everyday, This digitalized information is heterogeneous and remained limited to a local domain only. How to integrate and share this scattered knowledge with simplicity remained a big challenge. In this paper, we propose a prototype of web application for accomplishing above task using web 2.0 features; it makes traditional academic digital libraries to form as a special case of collaborative environment. This application enables users to customize their own resources to form their own virtual digital library. Further users can utilize personalized information of other users working in similar research domain to form true collaborative environment. The model and framework for the new look of academic digital library is presented.

• ETRI Journal
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• v.39 no.4
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• pp.525-534
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• 2017

A hardware-acceleration architecture that separates virtual network functions (VNFs) and network control (called HSN) is proposed to solve the mismatch between the simple flow steering requirements and strong packet processing abilities of software-defined networking (SDN) forwarding elements (FEs) in SDN/network function virtualization (NFV) architecture, while improving the efficiency of NFV infrastructure and the performance of network-intensive functions. HSN makes full use of FEs and accelerates VNFs through two mechanisms: (1) separation of traffic steering and packet processing in the FEs; (2) separation of SDN and NFV control in the FEs. Our HSN prototype, built on NetFPGA-10G, demonstrates that the processing performance can be greatly improved with only a small modification of the traditional SDN/NFV architecture.

• Journal of Communications and Networks
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• v.11 no.2
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• pp.196-206
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• 2009

Over the last five years, relaying or multihop techniques have been intensively researched as means for potentially improving link performance of wireless networks. However, the data rates of relays are often limited because they cannot transmit and receive on the same frequency simultaneously. This limitation has come to the attention of researchers, and recently a number of relay techniques have been proposed specifically to improve the data efficiency of relaying protocols. This paper surveys transmission protocols that employ first single relays, then multiple relays and finally multiple antenna relays. A common feature of these techniques is that novel signal processing techniques are required in the relay network to support increased data rates. This paper presents results and discussion that highlight the advantages of these approaches.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.784-787
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• 1999

This paper describes a direct digital frequency synthesizer using the CORDIC algorithm, which can be implemented efficiently for a digital sinusoid synthesis. To optimize the hardware design parameters, we perform numerical analysis of the quantization effects for the CORDIC-based architecture. A pipelined architecture is employed to obtain a high data throughput,. We estimate and summarize its hardware costs for a variable accuracy, and a CORDIC-based architecture for 9 bit accuracy is emulated in FPGA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.698-712
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• 1996

This paper deals with the security planning for digital mobile communications provided in CDMA and GSM security standards and the public key crytosystem security methods. In this paper, we provide a comparison of these methods with repect to security services and key managment. Based upon this analysis, we also present a secunity planning which is applicable to the domestic digital mobile communications.