• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1076-1089
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• 2012

Home automation networks are good environments for merging sensor networks and consumer electronics technologies. It is very important to reduce the energy consumption of each sensor node because sensor nodes operate with limited power based on a battery that cannot be easily replaced. One of the primary mechanisms for achieving low energy operation in energy-constrained wireless sensor networks is the duty-cycle operation, but this operation has several problems. For example, unnecessary energy consumption occurs during synchronization between transmission schedules and sleep schedules. In addition, a low duty-cycle usually causes more performance degradation, if the network becomes congested. Therefore, an appropriate control scheme is required to solve these problems. In this paper, we propose UDC (Unsynchronized Duty-cycle Control), which prevents energy waste caused by unnecessary preamble transmission and avoids congestion using duty-cycle adjustment. In addition, the scheme adjusts the starting point of the duty-cycle in order to reduce sleep delay. Our simulation results show that UDC improves the reliability and energy efficiency while reducing the end-to-end delay of the unsynchronized duty-cycled MAC (Media Access Control) protocol in sensor-based home automation networks.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.191-195
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• 2006

국내와 북미 지역에서 ATSC DTV 방송 서비스가 시작된 이래 수신 성능을 개선하기 위한 계속적인 노력이 경주되어 왔다 [1]-[6]. 본 논문에서는 2005 년 8 월 캐나다 CRC (Communications Research Center) 센터의 테스트 결과를 토대로 최신 ATSC 수신기의 성능을 고찰해 보고자 한다 [4]. CRC 테스트는 수신 감도, 다중 경로 환경에서의 수신 성능, 간섭 신호에 대한 강건성 등 다양한 항목에 걸려 실시되었으며, A/74 권고안에 기술된 난시청 지역의 50 개 신호 샘플에 대한 성능 평가를 포함하고 있다. 테스트에 사용된 ATSC 수신기는 당사에서 개발한 최신 칩 (GEMINI)을 탑재한 것으로 파일럿 (pilot) 신호가 손상된 경우에도 안정적인 동기 획득이 가능하며 현존 수신기 중 가장 넓고 강력한 반사파 (ghost) 제거 성능을 보유하고 있다. CRC 테스트 결과와 국내외 필드테스트 결과는 최신 ATSC 수신기가 A/74 권고안뿐만 아니라 각종 성능 지표에서 이전 수신기에 비해 대폭 개선되었음을 확인시켜 준다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.59-62
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• 2006

본 논문에서는 OpenGL Rendering을 이용한 모델기반 3D 다시점 영상의 객체 구현을 위한 구성과 각 모듈에 적용되는 알고리즘에 대해 중점적으로 연구하였다. 한 장의 텍스쳐 이미지와 깊이 맵(Depth Map)을 가지고 다시점 객체를 생성하기 위해, 먼저 깊이 정보의 전처리 과정을 거친다. 전처리 된 깊이 정보는 OpenGL상에서의 일정 간격의 꼭지점(Vertex) 정보로 샘플링 된다. 샘플링 된 꼭지점 정보는 깊이 정보를 z값으로 가지는 3차원 공간 좌표상의 점이다. 이 꼭지점 정보를 기반으로 텍스쳐 맵핑 (texture mapping)을 위한 폴리곤(polygon)을 구성하기 위해 딜루이니 삼각화(Delaunay Triangulations) 알고리즘이 적용되었다. 이렇게 구성된 폴리곤 위에 텍스쳐 이미지를 맵핑하여 OpenGL의 좌표 연산을 통해 시점을 자유롭게 조정할 수 있는 객체를 만들었다. 제한된 하나의 이미지와 깊이 정보만을 가지고 좀 더 넓은 범위의 시점을 가지는 다시점 객체를 생성하기 위해, 새로운 꼭지점을 생성하여 폴리곤을 확장시켜 기존보다 더 넓은 시점을 확보할 수 있었다. 또한 렌더링된 모델의 경계 영역 부분의 깊이정보 평활화를 통해 시각적인 개선을 이룰 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.209-212
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• 2005

This paper introduces interactive multi-view contents authoring system based on MPEG-4. The MPEG-4 standard, which aims to provide an object based audiovisual coding tool, has been developed to address the emerging needs from communications, interactive broadcasting as well as from mixed service models resulting from technological convergence. Due to the feature of object based coding, it has been considered that MPEG-4 is the most suitable for interactive broadcasting content production. This feature is suitable for creation of the content which provides multiple views of object or scene in interactive manner. In this paper, we categorize the multi-view visual content into two types: panoramic multi-view content and object multi-view content. And design and implementation of the authoring system for interactive multi-view contents is presented. We believe that the proposed method can be effectively used for further deployment of MPEG-4 content to various interactive applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.653-658
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• 2015

Cloud service is one of major challenges in IT industries. In cloud environment, service providers predict dynamic user demands and provision resources to guarantee the QoS to cloud users. The conventional prediction models guarantee the QoS to cloud user, but don't guarantee profit of service providers. In this paper, we propose a new resource allocation mechanism using Q-learning algorithm to provide the QoS to cloud user and guarantee profit of service providers. To evaluate the performance of our mechanism, we compare the total expense and the VM provisioning delay with the conventional techniques with real data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1640-1650
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• 2010

To prepare for the network centric warfare, Korea Joint Tactical Data Link System(KJTDLS) has been developed by the South Korean military recently and its development is divided into two phases: basic and complete ones. Due to the limited bandwidth and low transmission efficiency of the developing KJTDLS (basic), lots of problems could be occurred when the TDMA protocol in Link-16 is applied. In this paper, a new dynamic TDMA frame structure for KJTDLS(basic) is proposed and the performance of the proposed is evaluated through the implementation of simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.517-525
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• 2010

The IPTV Service provides various interactive services beyond the level of being able to substitute cable TV. The IPTV system is to be decentralized gradually in which one server conducts all tasks. Primarily, deliberation of media needs to be changed into a system in which relayer and peer from the central server is utilized. Secondarily, the way of controling IPTV network need to be decentralized. Unlike the current client-server system, P2P(Peer To Peer), the main technology of decentralized IPTV is able to provide a service by cooperation of each node. Dealing with live streaming IPTV system which is based on the P2P protocol, this paper design the pure P2P IPTV structure and does verify the performance of P2P IPTV structure by realizing real system.

• Journal of Information Technology Applications and Management
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• v.24 no.1
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• pp.11-24
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• 2017

Due to development of smart and network technologies, social network service (SNS) has become popular in daily life. With increasing use of SNS, the scope of communication has been widened. Lots of activities can be easily shared daily on SNS. Differing with opinions about more activated communication on SNSs, some people have viewpoints that, in some cases, communications may be decreased among SNS users. This research is to investigate whether there may be the differences among generations in the social network age. Major concerns of study are as follows. First, there may be differences in age related to the decrease of communication activities. On the other hand, there may be differences among generations related to the increase of communication. Two research steps have been adopted that the FGI (focus group interview) was to understand. Defining actual communication status was the first step, and an empirical approach, a survey to verify hypotheses, was performed as the second step. Key findings of the study were that older generations perceived communication has been decreased. Research results can provide implications regarding characteristics of SNS communication.

• Journal of the Speleological Society of Korea
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• no.61
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• pp.65-82
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• 2000

The remarkable development of information technology today is significantly increasing the desire for related services as it allows one to process and transmit information fast and accurately as well as in an efficient way. Particularly, the spread of the Internet even changes our life pattern, not to mention allowing us to provide or share information. One of the most typical example is electronic commerce. The e-commerce industry, which is build upon informations super high way, is growing rapidly, backed on the development of communications technology and the combination of various media. Companies are active In embracing and utilizing the cutting-edge information technology, whereas the tourism industry in general is still at a rudimentary stage. Therefore, it is expected that the industry will harness e-commerce in many aspects. Tourism, in its characteristic, has a variety of sectors, and cross-sector cooperation is essential. Therefore, the industry can provide better services by connecting or integrating network systems and taking advantage of e-commerce, while it is of no less importance to have informal ion system for promoting products. This thesis will look into and the basic concept and role of e-commerce as well as the existing tourism information system. It will also study ways to make good use of e-commerce by adopting it into the tourism information system.

• Journal of Digital Contents Society
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• v.19 no.7
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• pp.1389-1395
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• 2018

Hybrid is explained based on the logic of combination such as cross, melding, permeation, fusion, convergence etc. Such combination shows that it is more creative and effective in case of heterogeneity as compared to homogeneity and the same kind, and hybrid character has its meaning as a mean to produce a new creative image. In the context, this study aims to analyze influencing relationship through a practical analysis on how formative requirements for hybrid characters affects consumer preference. For the foregoing, this study conducted multiple regression analysis having familiarity, originality, meaningfulness, diversity as independent variables for formative requirements for characters, and consumer preference as a dependent variable. Analysis results show that familiarity, originality, diversity have a positive effect on consumers, whereas, meaningfulness has no significant impact on the consumer preference.