• 한국멀티미디어학회논문지
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• 제6권6호
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• pp.1034-1045
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• 2003

본 논문에서는 무선 네트워크 환경에서 이동 호스트들에게 멀티미디어 서비스의 제공을 위한 멀티캐스트 전송 기법을 제안한다. 핸드오프 과정 중에 발생하는 패킷 손실 등을 해결하기 위해 본 논문에서는 오버랩 영역을 이용한 Pre-join 기법을 제안한다 그리고 실시간 멀티미디어 응용에서의 연속적인 서비스 지원을 위해 본 논문에서 제안된 Crossover 라우터에서의 버퍼링 기법은 Remote Subscription 기법에서 제안한 최적 경로 기법에 기반하여 영역들의 오버랩 된 특성을 이용한 호스트의 이동 방향 탐지 기법을 적용하였다. 제안한 기법의 성능을 평가하기 위해 NS-2를 이용하여 Mobile If의 Bi-directional tunneling 기 법 과 Remote Subscription 기 법, 그리 고 MoM 기법과 비교 실험하였다 실험 결과 본 논문에서 제안한 방법은 이동 호스트에게 최적의 경로를 제공해 줄 뿐 아니라, 패킷 손실을 해결하기 위한 Pre-join 혹은 Crossover 라우터 버퍼링 기법을 사용함으로써 비교 실험한 다른 기법들에 비해 네트웍 부하와 패킷 손실, 대역폭 사용 측면에서 향상된 성능을 보였다.

• 대한전자공학회논문지TC
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• 제44권1호
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• pp.1-9
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• 2007

디지털 멀티미디어 방송(DMB: Digital Multimedia Broadcasting)은 음성, 영상, 데이터와 같은 다양한 멀티미디어 신호를 디지털 방식으로 변조하여 이동 중에 방송을 청취 할 수 있는 차세대 디지털방송 서비스이다. 하지만 한정된 대역폭으로 인한 비디오 전송율의 한계에 따라 최대 CIF(Common Interleaved Frame)급 화면해상도까지 서비스가 가능하다. 지상파 DMB 전송 고도화 망에서는 계층 변조(Hierarchical Modulation) 전송 기법을 통하여 추가의 전송대역폭을 확보할 수 있으며, 스케일러블 비디오 코딩(Scalable Video Coding) 부호화 방식을 이용하여 고전송효율/고품질의 이동 멀티미디어 방송서비스를 제공할 수 있다. 본 논문에서는 기존의 지상파 DMB가 제공할 수 있는 품질 및 기능을 뛰어넘어, 고품질의 이동 멀티미디어 방송서비스가 가능한 지상파 DMB 전송고도화 망에서의 스케일러블 비디오 적용 방법을 제안한다.

• 한국멀티미디어학회논문지
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• 제11권10호
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• pp.1385-1391
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• 2008

네트워크 기반 이동성 지원 기술인 Proxy MIPv6는 이동 노드가 Mobile IPv6 기능을 수행하지 않더라도 Proxy MIPv6 도메인 내에 위치하는 LMA (Local Mobility Anchor) 및 MAG (Mobile Access Gateway)에 의해 단말의 IP이동성을 지원한다. 그러나 이동 노드가 Proxy MIPv6 도메인 내에 존재하는 이동 네트워크 내부로 이동할 경우에는 MAG와 통신할 수 없으므로 더 이상 로컬 이동성 지원을 받을 수 없게 된다. 따라서 본 논문은 이동 라우터에 MAG 기능을 부여함으로써 Proxy MPv6도메인 내에서 중첩 네트워크 이동성을 지원하는 방안을 제안하고 그 성능을 평가한다. 성능 분석 결과 핸드오버 지연, 시그널릴 비용, 및 패킷 손실률 등에 있어서 제안 방안의 우수성을 확인할 수 있었다.

• 한국멀티미디어학회논문지
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• 제18권4호
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• pp.499-505
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• 2015

Security supports are a significant factor in the design of mobile ad hoc networks. In the dynamic topology where the node changes frequently, private key generation and revocation for newly joining and leaving nodes must be considered. In addition, the identities of individual nodes must be protected as well in mobile networks to avoid personal privacy concerns. This paper proposes ID-based private key revocation scheme and non-interactive key agreement scheme in anonymous MANETs. The proposed scheme provides the user privacy using pseudonyms and private key generation and revocation schemes with consideration of dynamic user changes. Therefore, our schemes can be applied in dynamic and privacy-preserving MANETs which are helpful to share multimedia data.

• International Journal of Internet, Broadcasting and Communication
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• 제12권4호
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• pp.33-41
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• 2020

Nowadays, distributed mobility management (DMM) approaches have been widely adopted to address the limitations of centralized architectural methods to support seamless data transmission schemes in wireless sensor networks. This paper deals with the end-to-end (E2E) integration of Network Mobility (NEMO) basic support protocol in distributed wireless sensor network systems in structural health and environmental monitoring of social overhead capital (SOC) public infrastructures such as bridges, national highways, tunnels, and railroads. The proposed scheme takes advantage of the features of both the NEMO basic support protocol and partially distributed network-based DMM framework in providing seamless data transmission and robust mobility support. The E2E seamless data transmission scheme allows mobile users to roam from fixed-point network access locations and mobile platforms (i.e., vehicles such as cars, buses, and trains) without disconnecting its current sessions (i.e., seamless handover).

• Journal of Multimedia Information System
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• 제5권3호
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• pp.155-162
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• 2018

Nowadays, the tracking technology of Quadrant Detector will become actual by new micro devices. Based on the past filed data of the reception experiment with COMETS satellite, we have studied on new device (AD8302, phase difference detector) was acquired and suspect its abilities. In 1998, we have developed a Quadrant Detector for mobile to track a weak signal from satellite on Ka band of COMETS. The Quadrant Detector is comprised of four dedicated feed components for reception under an environment of Nakagami - Rician fading, and one transmission and reception feed component. We were successful in receiving a 23 GHz beacon signal from ICE transponder of the COMETS and succeeded in tracking the satellite from a moving vehicle at speeds of approximately 10 ~ 20 Km/h on paved roads. In 2018, with new device AD8302, we have verified new QD system and performed a simulation, based on the past filed experiment. This new device shall be improving the tracking abilities from mobile body on the earth to the multimedia satellite.

• Journal of Multimedia Information System
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• 제1권1호
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• pp.23-43
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• 2014

With the rapidity of the development on electronic technology, various mobile devices are produced to make human life more convenient. The user is always in constant search of middle with ease of deployment. Therefore, the development of infrastructure and application with ubiquitous nature gets a growing keen interest. Recently, the number of pervasive network services is expanding into ubiquitous computing environment. To get desired services, user presents personal details about this identity, location and private information. The information transmitted and the services provided in pervasive computing environments (PCEs) are exposed to eavesdropping and various attacks. Therefore, the need to protect this environment from illegal accesses has become extremely urgent. In this paper, we propose an anonymous authentication and access control scheme to secure the interaction between mobile users and services in PCEs. The proposed scheme integrates a biometric authentication in PKI model. The proposed authentication aims to secure access remote in PCE for guaranteeing reliability and availability. Our authentication concept can offer pervasive network service users convenience and security.

• 한국컴퓨터정보학회논문지
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• 제22권10호
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• pp.41-45
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• 2017

Virtual Reality (VR) is widely used in various fields, and it is expanding game and movie toward health care, business Software, education, and web services. Especially various researches are actively conducted in the field of exhibition, utilizing smart phone based detachable HMD (Head Mounted Display). The VR exhibition solves addresses both temporal and spacial constraints overcoming the unilateral information transfer exhibitions. This paper presents a method to overcome the limitation of time, space, and unidirectional information transfer in offline exhibition, and also presents a new method that utilizes multimedia visual design artwork as VR contents.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.546-558
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• 2017

The amount of multimedia traffic over the Internet has been increasing because of the development of networks and mobile devices. Accordingly, studies on multicast, which is used to provide efficient multimedia and video services, have been conducted. In particular, studies on centralized multicast tree construction have attracted attention with the advent of software-defined networking. Among the centralized multicast tree construction algorithms, the group Takahashi and Matsuyama (GTM) algorithm is the most commonly used in multiple multicast tree construction. However, the GTM algorithm considers only the network-cost overhead when constructing multicast trees; it does not consider the temporary service disruption that arises from a link change for users receiving an existing service. Therefore, in this study, we propose a multiple multicast tree construction algorithm that can reduce network cost while avoiding considerable degradation of service quality to users. This is accomplished by considering both network-cost and link-change overhead of users. Experimental results reveal that, compared to the GTM algorithm, the proposed algorithm significantly improves the user-experienced quality of service by substantially reducing the number of linkchanged users while only slightly adding to the network-cost overhead.

• International Journal of Advanced Culture Technology
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• 제8권3호
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• pp.223-230
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• 2020

Companies have made an investment of cost and time to optimize processing of a new business model in a cloud environment, applying collaboration technology utilizing business processes in a social network. The collaborative processing method changed from traditional BPM to the cloud and a mobile cloud environment. We proposed a collaborative system for operating processes in social networks using MOXMDR-DAI+ (eXtended Metadata Registry-Data Access & Integration based multimedia ontology). The system operating cloud-based collaborative processes in application of MOXMDR-DAI+, which was suitable for data interoperation. MOXMDR-DAI+ applied to this system was an agent effectively supporting access and integration between multimedia content metadata schema and instance, which were necessary for data interoperation, of individual local system in the cloud environment, operating collaborative processes in the social network. In operating the social network-based collaborative processes, there occurred heterogeneousness such as schema structure and semantic collision due to queries in the processes and unit conversion between instances. It aimed to solve the occurrence of heterogeneousness in the process of metadata mapping using MOXMDR-DAI+ in the system. The system proposed in this study can visualize business processes. And it makes it easier to operate the collaboration process through mobile support. Real-time status monitoring of the operation process is possible through the dashboard, and it is possible to perform a collaborative process through expert search using a community in a social network environment.