• Information and Communications Magazine
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• v.23 no.10
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• pp.53-62
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• 2006

다양한 유무선 액세스망들이 IP기반 공통의 코어망을 이용할 수 있도록 연동되는 BcN에서는 휴대단말이 이종망간에 이동하는 상황에서도 끊김 없는 서비스를 제공하는 것이 필수 요소 기술이고, 이를 지원 하기 위해서 고속의 핸드오버 기능 및 위치 관리 기능이 필요로 된다. 특히 고속의 핸드오버를 수행하기 위해서는 액세스망에 의존적인 데이타링크 계층 기능들과 IP기반 이동성 기능들이 밀접히 연계되어 동작되어야 한다. 본 고에서는 IP망에서의 대표적인 이동성 지원 방법인 Mobile IP 기술과 데이터링크 계층의 이동성 관련 트리거 정보를 통일돈 형태로 상위 계층으로 전달하는 IEEE 802.21 MIH(Media Independent Hanover) 기술에 대해 소개하고 Mobile IP와 MIH기술을 바탕으로 이종망간에 끊김없는 이동성을 제공하는 방법에 대해서 살펴볼 것이다.

• Journal of Communications and Networks
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• v.11 no.4
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• pp.406-415
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• 2009

In this work, we consider performance modeling of a wireless sensor network with a time division multiple access (TDMA) media access protocol with slot reuse. It is assumed that all the nodes are peers of each other and they have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with unreliable nodes with on and off states. Active and sleep modes of sensor nodes are modeled with on and off states of unreliable nodes. We determine the joint distribution of the sensor node queue lengths in the network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node and the network throughput. We present numerical results as well as simulation results to verify the analysis. Finally, we discuss how the derived results may be used in the design of sensor networks.

• International Commerce and Information Review
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• v.8 no.1
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• pp.143-163
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• 2006

The terms electronic trade, electronic trading and electronic commerce are often used interchangeably, and refer to trading transactions conducted using electronic media. Electronic trade is business-to-business transactions in an industrial context, while electronic commerce refers to retailing and the consumer sector as well as mass marketing. The Electronic trade process is defined as a flow of information (documents) exchanged between enterprises and trade-related firms (shipping companies, foreign exchange banks, forwarders, etc.) in the course of implementing a series of export and import procedures. Electronic trading systems exploit information technology to improve the efficiency of communications and/or to alter the nature of inter-organizational transactions. Many studies exist about the adoption of inter-organizational systems (IOS) and electronic data interchange (EDI), but few focus on electronic trade. The literature on exporting companies's electronic trade adoption and implementation, although extensive, consists mainly of exploratory studies focusing on technological characteristics such as barriers, benefits and usage. The purpose of this study is to broaden this perspective by investigating the environmental, organizational and technological drivers of business-to-business e-commerce adoption.

• Information Display
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• v.15 no.5
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• pp.22-32
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• 2014

The current research intends to quantify the surround luminance effects on the shape of spatial luminance CSF and to propose an image quality evaluation method that is adaptive to both surround luminance and spatial frequency of a given stimulus. The proposed image quality method extends to a model called SQRI[8]. The non-linear behaviour of the HVS was taken into account by using CSF. This model can be defined as the square root integration of multiplication between display MTF and CSF. It is assumed that image quality can be determined by considering the MTF of the imaging system and the CSF of human observers. The CSF term in the original SQRI model was replaced by the surround adaptive CSF quantified in this study and it is divided by the Fourier transform of a given stimulus. A few limitations of the current work should be addressed and revised in the future study. First, more accurate model predictions can be achievable when the actual display MTF is measured and used instead of the approximation. Then, a further improvement to the model prediction accuracy can be made when chromatic adaptation of the HVS is taken into account[45-46].

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.723-727
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• 2002

In this paper a new remote control system for operating indoor gas(LPG) range safely based on PLM(Power Line Modem) and telephone is developed because it would make disasters of properties and lives by user's carelessness or worker's bad installation, etc. The system includes the following elements: a telephone line interface system for user to call from the outdoors to the indoors, a communication system using the power line as a communication media, a system of cutting off gas and a alarm system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.799-807
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• 2004

In this paper, a security mechanism for a VoIP system based on SIP was implemented. This was satisfied sec security requirement of RFC 3261. The SIP standard proposes a HTTP digest authentication for user authentication mechanism, TLS for hop-by-hop security and S/MIME for end-to-end security. SRTP draft was implemented for media security. We also analyzed security of proposed SIP standard.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.246-260
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• 2016

A major challenge achieving scalable access control for a large number of subscribers in a public broadcast is to distribute key update messages reliably to all stateless receivers. However, in a public broadcast, the rekeying messages can be dropped or compromised during transmission over an insecure broadcast channel, or transmitted to receivers while they were off-line. In this study, we propose a novel group key management scheme. It features a mechanism to allow legitimate receivers to recover the current group key, even if they lose key update messages for long-term sessions. The scheme uses short hint messages and member computation. Performance analysis shows that the proposed scheme has the advantages of scalability and efficient rekeying compared to previous reliable group key distribution schemes. The proposed key management scheme targets a conditional access system in a media broadcast in which there is no feedback channel from receivers to the broadcasting station.

• Information and Communications Magazine
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• v.29 no.10
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• pp.25-29
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• 2012

최근 전 세계적으로 차세대 웹 기술인 HTML5(Hyper Text Markup Language ver. 5)는 기존 웹 기술의 고도화를 넘어 미래 IT융복합 서비스 실현을 위한 플랫폼으로서 그 중요성이 더욱 증대되고 있다. 본 고에서는 HTML5를 중심으로 플랫폼으로서의 미래 스마트미디어 (Smart Media)를 전망해보고자 한다. 특히 HTML5의 등장은 최근 도메인간 서비스 융 복합이 다변화되는 ICT 환경에서 그 역할이 더욱 중요해지고 있으며, 다양해지는 서비스와 미디어들과의 결합은 더욱 똑똑해지는 미디어 즉 스마트미디어의 실현으로 이어지고 있다. 따라서, 본 고에서는 미래 서비스 융복합 기술 그리고 나아가 플랫폼으로써 HTML5에 대한 주요 특징과 시사점을 살펴보며, 스마트 미디어 플랫폼으로서의 역할과 활용 및 대응 전략 등을 고찰해보고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.439-441
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• 2002

Real-time Transport Protocol (RTP) is widely used in VoIP stacks charging the multimedia data delivery. Concerning with payload protection of RTP packets, Secure RTP has been discussed in IETF AVT group to provide confidentiality and authentication features using block ciphering and message authentication coding. However, Secure RTP only concentrates on payload protection. Signcryption is a good candidate for key agreement. This paper proposes a key establishment protocol using Signcryption and shows example implementation of a secure VoIP application based on Secure RTP with the proposed scheme.

• Journal of Radiation Industry
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• v.2 no.1
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• pp.35-42
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• 2008

The purpose of this study is to observe how the public impression of radiation is changing over the North Korea's nuclear bomb test. We found that the nuclear bomb test brought more negative impressions of radiation, but, in one year, more positive ones prevailed as in the pre-bomb-test. Those positive impressions were found to be composed of useful and positive elements mostly relative to health care. This suggests that we need to apply radiation (fusion) technology to solving everyday life problems in order to bring more positive impressions of radiation.