• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.213-220
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• 2008

In a distributed processing environment composed of many independent systems connected by networks, it is very important and difficult to make time synchronization between the systems. Especially in the USN environment the time synchronization is still more difficult than in general distributed processing environment because energy is limited and communication function is feeble. Even though of these difficulties, the USN environment requires higher precision of time synchronization. We of the typical applications requesting very strict time synchronization in USN is TDMA MAC. This paper proposes and evaluates a new time synchronization protocol HTSP(Hierarchical Time Synchronization Protocol) which is an advanced version of the FTSP(Flooding Time Synchronization Protocol) published recently. The time synchronization precision of the HTSP is equal to that of the FTSP, but the energy consumption of the HTSP is lower than that of the FTSP owing to the reduced number of broadcast messages. The simulation results show that the energy consumption of the HTSP is only 74% of that of the FTSP.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.183-190
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• 2012

Internet Protocol Television(IPTV) is the use of an IP broadband network to deliver television (cable TV type) services to the end user. Traditional telecommunications service providers as well as alternate service providers and Internet service providers can utilize their IP networks (and broadband consumer access) to deliver broadcast TV, Video on Demand (VOD) and other Internet services to the consumer. As digital technologies progress, illegal copy and redistribution of IPTV content become easier and simpler. Therefore it is required to protect IPTV content or service. In this paper, we analyze the security threats and requirements. We also discuss related issues and solutions for IPTV.

• Journal of Digital Convergence
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• v.9 no.2
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• pp.1-13
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• 2011

This study aims to analyse the process of digital switchover in the UK, which is regarded as one of the most successful cases in the world, and to examine efficient plans for the future digital switchover project in Korea through the UK's case. The digital switchover in the UK shows with no doubt the significance of integrated government policies, collaboration between relevant governmental organisations, and the public service broadcaster. Along with this, active and detailed Public Relations (PR) should take place, helping the citizens realise the efficiency of the phased switchover region by region and the measures to resolve the gaps between all social brackets. To sum up, the successful digital transfer is not only achieved by governmental policy and technological preparation from broadcasters, but also by voluntary citizen participation. Government officers and broadcast executives need to realise this and should focus on communicating with citizens.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.411-418
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• 2016

Digital broadcast environment led to the emergence of UHDTV following HDTV. The demands for realistic images which are created with the use of UHDTV have been applied to various fields. Of various application methods, multiplanar imaging, which is used to display high definition image contents after multiple HD or UHD displays are connected with each other up and down, and left and right, is often applied to display images and the advertising market. Today, the firms that make high-definition multiplanar images mostly use their independently developed program. Therefore, it costs higher than other general works. For the reason, multiplanar image contents are mostly made in the way of enlarging HD images over 2 to 5 times. In this experiment, the software application widely known for UHDTV based multiplanar images is applied to test a method of implementing UHD panoramic realistic images without quality degradation.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.249-254
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• 2013

The number of channels are increased into several hundreds of channels when coming out the digital broadcasting era. In this environment, viewers searching for programs will be very difficult to do. In addition, recent popularization of smart devices are receiving the services that they previously had not been given to. A TV program recommended a system that has been studied as a way to solve these problems. However, most studies have been studied in most web-based research results when applied to broadcast TV for TV program recommendations. In particular, the combination of the current members who watch TV are not considered. In this paper, the environment and TV viewers are considering a combination of the members of the TV program's recommended system proposal. In order to make a group deal successful, we employ the face recognition.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.12 s.354
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• pp.1-8
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• 2006

In this paper, we propose carrier phase synchronization algorithm which are base on turbo coded system for DVB-RCS. There have been two categories of phase estimator, single estimator outside turbo code decoder and multiple estimators inside turbo code decoder. In single estimator, we use the estimation algorithm that ML(Maximum Likelihood) and LMS(Least Mean Square), also three different soft decision methods are proposed. Multiple estimator apply PSP(Per Survivor Processing) algorithm additionally. We compared performance between single estimator and Multiple estimator in AWGN channel. We presented the two methods of PSP algorithm for performance elevation. First is the Bi-directional channel estimation and second is binding method.

• Korean journal of communication and information
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• v.21
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• pp.63-86
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• 2003

Digital TV is expected to usher in a new era of TV. Thanks to digital and network technologies, TV will no more be a dumb terminal as it is today. It will incorprate the computer and thus become an intelligent device which serves not only high quality broadcast programming, but a variety of information services much like the current networked-computer. However, the real world picture of digital TV is clearly different from such a rosy vision. Albeit too early to tell, the cases in Europe and the US attest that the digital transition suffers a setback in terms of technology, policy, business, marketing, and the users. As such, the digital transition is generally problematized in terms of policy, business model, marketing strategy, and so on. Comparatively speaking, the issues of technology, policy, business and marketing are not so complicated than that of digital TV users because of the cultural issues involved in the adoption of digital TV. In other words, the technological transition to digital TV is far easier than its cultural transition. The cultural transition demands policy makers and industries of different approaches to successfully facilitating the digital transition.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.7
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• pp.9-19
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• 2004

WLAN (Wireless Local Area Networks) needs error recovery and flow control schemes to support reliable multicast protocol. Limited wireless bandwidth, as well as queuing losses caused by the asymmetric wired/wireless interactions, demands more effective approaches for reducing packet losses. Moreover, since the wireless channel is a shared broadcast medium, if sender receives feedback information simultaneously from several receivers, the feedback delays data frame transmission of forward direction by introducing channel congestion and burden at the sender. Therefore, it is important to minimize the amount of feedback information from receivers. In this paper, we propose an ARS(Adaptive Redundancy Scheme) that combines FEC(Forward Error Correction) using channel state estimation and ARQ(Automatic Repeat Request) both to reduce the amount of feedback information and the number of retransmissions and to guarantee high data reliability in a WLAN multicast environment. Performance of the proposed scheme is evaluated by means of analysis and simulations in AWGN and Rayleigh fading channels. The results show that the proposed scheme reduces the amount of feedback information and the number of retransmissions and guarantees high data reliability, while keeping throughput efficiency similarly with the conventional FEC and ARQ scheme.

• Journal of the Korean Society of Food Culture
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• v.28 no.4
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• pp.339-347
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• 2013

Yaksun, a medicinal diet, has been traditionally prepared and applied (based on theories in oriental medicine) for the modulation of disease symptoms and signs. However, restaurants that serve and claim Yaksun mainly focus on stamina foods. A consistent definition of Yaksun has not been provided, which can confuse the public interpretation of Yaksun. The purpose of this study was to investigate the perception of Yaksun in Korean adults living in Seoul, Gyeonggi, and Chungbuk regions. Among the participants (M=55, F=168, 25y), only 10.4% understood the definition of Yaksun (mainly through the broadcast media). The frequency of Yaksun consumed when eating out was 2~3 times per month in 50.2% of participants. The main reason for choosing a Yaksun menu (46.3% of participants) when eating out was for health. The mean satisfaction score of Yaksun was $3.5{\pm}0.8$ on the five point Likert scale. Participants highly agreed ($3.8{\pm}0.8$) that Yaksun is composed of nutritious foods combined with oriental medicinal herbs for the treatment of disease, which was significantly higher in groups with learning experience on Yaksun (p<0.05). Interestingly, participants showed neutral to the description, that a diet without oriental medicinal herbs is not Yaksun ($3.1{\pm}1.0$), which was significantly different between genders (p<0.05). Men recognized more than women that Yaksun should be based on oriental medical theory (p<0.05) and should be prepared for the prevention or treatment of diseases (p<0.05). In conclusion, the concept and terminology of Yaksun need to be defined and publicized in modern diet.

• Convergence Security Journal
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• v.12 no.3
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• pp.123-129
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• 2012

Due to the high digital technology, various devices such as TV, PC, smartphone, and pad computer are connected to each other using internet and under the circumstance internet services of which the running platforms are mainly PC become "N-screenlized" by extending their service platform to non-PC devices. As a digital TV has outstanding features of being the most influential device in the living room and having the wide spectrum of users, several internet services has been ported on the digital TV platform (in the form of data services) in order to enhance their brand powers. Most of the services, however, failed to get a satisfactory results as the data services are defeated by the broadcasting contents in the competition for the viewer's interests. In the paper, the design guidelines that make data services not to compete with the broadcasting contents are proposed and a prototype of a data service that accommodates the guidelines is introduced. The prototype, called "TV ideal-type world-cup", does not disturb a viewer's watching broadcast contents and channel-changing behavior while it is running and its service flow is designed for a viewer to achieve the goal of service in a few minutes so that the viewer can enjoy the service in a commercial period.