• ETRI Journal
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• 제39권1호
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• pp.51-61
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• 2017

This paper demonstrates a systematic approach for the design of broadband, high efficiency, high power, Class-AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design. As a result, the use of a computer-aided simulation is most often the best way to achieve these goals; however, an appropriate initial value and a systematic approach are necessary for the simulation results to rapidly converge. These objectives can be accomplished with a minimum of trial and error through the following techniques. First, signal gain variations are reduced over a wide bandwidth using a proper pre-matching network. Then, the source and load impedances are satisfactorily obtained from small-signal and load-pull simulations, respectively. Finally, two high-order Chebyshev low-pass filters are employed to provide optimum input and output impedance matching networks over a bandwidth of 100 MHz-500 MHz. By using an EM simulation for the substrate, the simulation results were observed to be in close agreement with the measured results.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (A)
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• pp.152-153
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• 2008

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.1027-1032
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• 1994

This paper introduces a interword modeling and a Viterbi search method for continuous speech recognition. We also describe a development of a real-time voice dialing system which can recognize around one hundred words and continuous digits in speaker independent mode. For continuous digit recognition, between-word units have been proposed to provide a more precise representation of word junctures. The best path in HMM is found by the Viterbi search algorithm, from which digit sequences are recognized. The simulation results show that a interword modeling using the context-dependent between-word units provide better recognition rates than a pause modeling using the context-independent pause unit. The voice dialing system is implemented on a DSP board with a telephone interface plugged in an IBM PC AT/486.

• Journal of Multimedia Information System
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• 제3권4호
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• pp.135-140
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• 2016

To improve the throughput of Device-to-Device (D2D) communication, we focus on the scenario where D2D pair can reuse multi-channel of cellular communication. However, as sharing same channel with cellular communication can cause interference between D2D communication and cellular communication, a proper interference management is needed. In this paper, we propose interference-based channel allocation to select the channels to be used by D2D communication and a solution from game theory perspective to optimize the D2D communication throughput under multi-channel as well as guarantee the interference from it to cellular network. The simulation results verify the stability of the proposed method.

• 한국도서관정보학회지
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• 제20권
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• pp.471-495
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• 1993

This paper focuses on issues in the convergence of library and information science and communication studies. Common research topics in both fields include scholarly communication, knowledge gaps, invisible colleges, diffusion of innovations, human interaction with communication technologies, information-seeking behavior, information theory, and the information society. To consider these two disciplines in this broader context, this paper compares these two discipline's paradigms, suggests four models of convergence, and traces bibliometric studies performed. This study may be of use to those studying scholarly communication or bibliometrics, to faculty constructing curricula in either of the disciplines, to communication and information science scholars seeking new areas of research, and to collection development librarians in drawing the boundaries of these disciplines.

• Journal of Information Processing Systems
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• 제16권6호
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• pp.1231-1237
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• 2020

In recent years, future information and communication technology (ICT) has influenced and changed our lives. Without various ICT-based applications, we would have difficulty in securely storing, efficiently processing, and conveniently communicating information. In the future, ICT will play a very important role in the convergence of computing, communication, and all other computational sciences and application. ICT will also influence various fields including communication, science, engineering, industry, business, law, politics, culture, and medicine. In this paper, we investigate the latest algorithms, processes, and services in future fields.

• 기술혁신연구
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• 제6권1호
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• pp.99-127
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• 1998

The purposes of this study are first, to plan communication strategies for promoting the 1st National Science Festival and other events of the April 1997's Science Month in Koreas; second, to monitor communication activities done for those events; third, to evaluate effects of communication activities. Both the Ministry of Science and Technology and the Korea Science Foundation were arranged to execute our planned communication strategies. Basically we utilized the three sequences of human behavioral condition : Exposure, attention, and cognition. For planning, we suggested concrete communication strategies for each sequence, for example, first, those for bringing exposure to every event, second, those for bringing attention to the event, and third, those for bringing cognition of the event. Those communication strategies were suggested to use specifics of newspapers, television programs, radio programs, commercial and corporate magazines, electric visual sign advertisements on the street, and computer communication. For monitoring and evaluation, we used the same three sequences as the criteria. For example, we monitored and evaluated how much exposure, attention or cognition an event got or which specific medium contributed to exposure to, cognition of an event. For monitoring, graduate students were dispatched to examine each event through watching and interviewing. For evaluation, about 950 of event participants and non-participants were surveyed by means of face-to-face interview. Overall, we found that newspaper articles and television programs contributed a lot to people's exposure to events of the April 1997's Science Month. Especially, newspaper played a major role of heightening exposure. However, most events and/or their science and technology content failed to get salient attention and its following active cognition. The 1st National Science Festival attracted much exposure, but had some problems of disorder and commercialism. This sharp increase of exposure and some attention were believed to have reinforced people's, especially event participants' positive opinion of science and technology which is part of scientific culture.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권8호
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• pp.3550-3566
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• 2020

As a widely used way to exfiltrate information, wireless covert channel (WCC) brings a serious threat to communication security, which enables the wireless communication process to bypass the authorized access control mechanism to disclose information. Unlike the covert channel on the network layer, wireless covert channels on the physical layer (WCC-P) is a new covert communication mode to implement and improve covert wireless communication. Existing WCC-P scheme modulates the secret message bits into the Gaussian noise, which is also called covert digital communication system based on the joint normal distribution (CJND). Finding the existence of this type of covert channel remains a challenging work due to its high undetectability. In this paper, we exploit the square autocorrelation coefficient (SAC) characteristic of the CJND signal to distinguish the covert communication from legitimate communication. We study the sharp increase of the SAC value when the offset is equal to the symbol length, which is caused by embedding secret information. Then, the SAC value of the measured sample is compared with the threshold value to determine whether the measured sample is CJND sample. When the signal-to-noise ratio reaches 20db, the detection accuracy can reach more than 90%.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 한국컴퓨터종합학술대회논문집 Vol.34 No.1 (A)
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• pp.192-193
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• 2007

• 한국문헌정보학회지
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• 제14권
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• pp.93-130
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• 1987

Scientific communication is an information exchange activity between scientists. Scientific communication is carried out in a variety of informal and formal ways. Basically, informal communication takes place by word of mouth, whereas formal communication occurs via the written word. Science is a highly interdependent activity in which each scientist builds upon the work of colleagues past and present. Consequently, science depends heavily on scientific communication. In this study, three mathematical models, namly Brillouin measure, logistic equation, and Markov chain are examined. These models provide one with a means of describing and predicting the behavior of scientific communication process. These mathematical models can be applied to construct quality filtering algorithms for subject literature which identify synthesized elements (authors, papers, and journals). Each suggests a different type of application. Quality filtering for authors can be useful to funding agencies in terms of identifying individuals doing the best work in a given area or subarea. Quality filtering with respect to papers can be useful in constructing information retrieval and dissemination systems for the community of scientists interested m the field. The quality filtering of journals can be a basis for the establishment of small quality libraries based on local interests in a variety of situations, ranging from the collection of an individual scientist or physician to research centers to developing countries. The objective of this study is to establish the theoretical framework for informetrics which is defined as the quantitative analysis of scientific communication, by investigating mathematical models of scientific communication.