• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3789-3809
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• 2014

Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.2
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• pp.101-107
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• 2014

In order to understand people's ideas about radio pagers and effects of the radio pagers on school violence prevention, the study analyzed a radio pager demonstration which was being participated by a total of 606 students. According to the findings from the analysis, first, when it comes to statistical differences between the two groups with the experience of school violence as either a victim or a assailant, both the victims and the assailants believed that the radio pagers is useful to prevent school violence. Both the groups were observed to be willing to use the radio pagers constantly. Second, regarding effects of the radio pagers on the school violence prevention, they were understood to have even a more positive influence both on the school violence prevention and the students' satisfaction with their school lives as a more number of the students possess the radio pagers, as the more the students need the radio pagers and lastly as the more the students feel content with the radio pagers. Based on the results of the analysis, implications and limits of the study were proposed.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.501-507
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• 2004

The uniquely large dimensions of Giant radio galaxies (GRGs) make it possible to probe for stringent limits on total energy content, Faraday rotation, Alfven speeds, particle transport and radiation loss times. All of these quantities are more stringently limited or specified for GRG's than in more 'normal' FRII radio sources. I discuss how both global and detailed analyses of GRG's lead to constraints on the CR electron acceleration mechanisms in GRG's and by extension in all FRII radio sources. The properties of GRG's appear to rule out large scale Fermi-type shock acceleration. The plasma parameters in these systems set up conditions that are favorable for magnetic reconnection, or some other very efficient process of conversion of magnetic to particle energy. We conclude that whatever mechanism operates in GRG's is probably the primary extragalactic CR acceleration mechanism in the Universe.

• Journal of the Korean Wood Science and Technology
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• v.39 no.2
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• pp.125-131
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• 2011

The characteristics of radio-frequency/vacuum drying Japanese larch boxed heart round logs with 150 mm and 210 mm in diameter and 2,500 mm in length, subjected to compressive loading, after the pretreatment of kerf were investigated. The results of this study were as the follows: The drying time of about 120 hours~130 hours was needed from green to about 15 percent of moisture content. The gradient of final moisture content for all specimens was very gentle in both longitudinal and transverse directions owing to dielectric heating. The surface checks seriously occurred although the occurrence extent of surface check for the kerfed specimens was slight compared with that for the control specimens because drying stress was relieved by kerf. The occurrence of surface checks for the L-specimen was more serious than that for the S-specimen.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.269-272
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• 2011

현재의 호스트 기반의 인터넷 구조는 확장성, 보안성, 네트워크 유연성에 제약을 갖고 있다. 이를 극복하기 위하여 미국, 유럽 중심으로 미래 인터넷 연구가 활발히 진행 중이며, 그 중에서도 컨텐츠 중심 네트워크에 대한 연구는 미래 인터넷 서비스 단계에서 주목을 받고 있다. 컨텐츠 중심 네트워크는 컨텐츠를 기반으로 통신을 하며, 컨텐츠 배포가 이루어지기 때문에 컨텐츠 이름과 이름 분석이 중요한 요소로 부각되고 있다. 본 논문에서는 CCN, DONA, PSIRP, Netlnf 네 가지 종류의 컨텐츠 중심 네트워크의 이름 구조와 이름 분석을 비교하고, 이를 통해 비디오 서비스에 적합한 구조와 확장성에 대해 조사 하였다.

• Korean journal of communication and information
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• v.78
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• pp.79-115
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• 2016

This study, by proposing a case study of community radio, attempts to expand the horizon of academic and social discussion on the medium that has been disproportionately skewed towards discourses on alternative media, technology, and programming content. As residents of local community actively participate in the production process, they reconstruct their cultural identities. In that sense, community radio is a medium that makes it possible the re-negotiation and reconfiguration of cultural identities of local residents. That is to say, a case study on the specific ways in which community residents appropriate community radio in reconstructing their identities offers us some entry points where we may come up with a new perspective on the identity of community radio. The results of fieldwork show that community radio, as it is closely intertwined with the residents' participatory cultural practices, is a medium of 'lived culture' -i.e., a medium that contributes to the making of civility, communitarianism, and social network. Community radio, then, may be redefined as an interactive medium that contributes to the formation of social rapport and solidarity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.189-196
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• 2011

As internet is getting advanced day by day, digital contents have been developed in various areas as killer content in the IT industry. It needs to develop lots of complicated digital content protect systems due to the enhancement and variety of user's multimedia devices. Although there are lots of protect systems based on DRM(Digital Rights Management) technology, it is difficult to provide secure protection because of the problems resulting from analog hole problem, inefficiency of key sharing and various independent protect technologies. Thus, in this paper, we propose a novel authentication and protect system based on RFID(Radio Frequency Identification) technology to solve the problems and show possibility of free content duplication and efficient contents management in smart home environments.

• The Journal of the Korea Contents Association
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• v.9 no.1
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• pp.131-138
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• 2009

This paper is about adult certification on Mobile RFID Service Environments coming through the combination of RFID(Radio Frequency IDentification) technology, as the core technology of ubiquitous environments, and mobile telecommunication technology. To overcome the shortcoming of simple adult certification on current internet, we suggest a framework for content-based classification and propose an adult certification system using it. At first, we explain conventional methods for adult certification, and show a criteria of content-based classification for preventing an exposure of adult contents from minors. Additionally, we describe data structure and system for the proposed adult certification on mobile RFID environment, and finish it with concluding remarks.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.185-192
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• 2013

In this paper, proposed to improve the performance of speech and mixed content signal classification using MFCC based on GMM probability model used for the MPEG USAC(Unified Speech and Audio Coding) standard. For effective pattern recognition, the Gaussian mixture model (GMM) probability model is used. For the optimal GMM parameter extraction, we use the expectation maximization (EM) algorithm. The proposed classification algorithm is divided into two significant parts. The first one extracts the optimal parameters for the GMM. The second distinguishes between speech and mixed content signals using MFCC feature parameters. The performance of the proposed classification algorithm shows better results compared to the conventionally implemented USAC scheme.

• ETRI Journal
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• v.40 no.1
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• pp.72-88
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• 2018

In the fifth generation (5G) era, the radio internet protocol capacity is expected to reach 20 Gb/s per sector, and ultralarge content traffic will travel across a faster wireless/wireline access network and packet core network. Moreover, the massive and mission-critical Internet of Things is the main differentiator of 5G services. These types of real-time and large-bandwidth-consuming services require a radio latency of less than 1 ms and an end-to-end latency of less than a few milliseconds. By distributing 5G core nodes closer to cell sites, the backhaul traffic volume and latency can be significantly reduced by having mobile devices download content immediately from a closer content server. In this paper, we propose a novel solution based on software-defined network and network function virtualization technologies in order to achieve agile management of 5G core network functionalities with a proof-of-concept implementation targeted for the PyeongChang Winter Olympics and describe the results of interoperability testing experiences between two core networks.