• Communications of Mathematical Education
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• v.25 no.1
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• pp.47-61
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• 2011

The purpose of this study is to suggest a professional development system for elementary teachers who wish enhance mathematical teaching. The learning community on elementary mathematical teaching was composed of fourth grade teachers in a elementary school and an expert from education university. The activities was processed as establishing of objectives and contents of the learning community, discussing and seeing good lesson video, planning the lesson in collaboration with members, practicing the lesson, and reflecting on activities. To analyze these activities, record materials of meetings, lesson videos, member's writing were used. The results reported that the learning community lead teachers to search the method of professional development and showed itself as the effective media to enhance elementary mathematical teaching professionalism.

• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.129-138
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• 2004

Even though the Internet applications such as e-mail and FTP are widely used, fax is still an important media for data communications till today. Many researches on security over the Internet data communication have been done over the years, on the other hand not many researches have been dedicated to the fax security issue which is as important as the Internet. In this paper, we describe the development of hardware and software of the embedded security fax server which increases the security in supporting existing fax. The developed system is designed and implemented to maintain security while minimizing the delay due to encryptionㆍdecryption. Since there's international or domestic tryptographic standard and each nation have their policy to restrict the use of cryptographic system, we adopt domestic standard cryptographic protocol admitted in Korea. And the system supports two modes： Security mode and Non-Security mode that user can choose from. The system can be applied directly which is the requirements of users at company ,End the government. We verify the performance and functioning of the system in various real environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1343-1355
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• 1997

Full motion video data is the most effective data type that transmits information in multimedia enviornment. VOD service is system that uses network to transmit full motion video data interactively. Therefore VOD service system must satisfy the following requirements. First, it should transmit high quality full motion video. Second, it should be able to control a large quantity of full motion video. Third, a user should be able to retrieve the full motion vide effectively. However the existing VOD service system is established based n file system that not only does it have disadvantages in managment such as transaction control but also it is not suitable for distributed multimedia environment. The goal of this research is to build a VOD service system that provides high-quality full motion video assuming information retrieval. In order to mainly search video data's bibliographical information and to manage related information, VOD service system and DBMS system are to be closely related. Also, to transmit high quality full motion video data, we use MTP$^{TM}$(Media Transfer Protocol) developed by StarLight. MTP$^{TM}$ guarantees high bandwidth that is necessary to tansmit high quality full motion video data effectively. In other hand TCP/IP which is used for information search does not guarentee high bandwidth as that in MTP$^{TM}$. Therfore VOD service system that seraches information managed by DBMS and transmits requried full motion video data should control different kinds of protocol simultaneously. This paper describes the configuration of VODB system that has solved these problems, implementation and efficiency of data applied system.stem.

• Journal of Broadcast Engineering
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• v.17 no.2
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• pp.262-269
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• 2012

Hybrid-ARQ and opportunistic relaying are the widely used schemes for obtaining diversity gain in wireless communications. In opportunistic relaying, channel state information(CSI) between relays and destination is required to select the best relay. But if the destination moves very fast, the CSI becomes outdated. In this paper, performance of hybrid-ARQ based opportunistic relaying with outdated CSI is analyzed in outage probability and throughput perspective. The analysis is verified by computer simulations.

• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.13-20
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• 2001

In this paper, we propose a new digital audio watermarking scheme In the cepstrum domain. We insert a digital watermark signal Into the cepstral components of the audio signal using a technique analogous to spread spectrum Communications, hiding a narrow band signal in a wade band channel. In our proposed method, we use pseudo-random sequences to watermark the audio signal. The watermark Is then weighted in the cepstrum domain according to the distribution of cepstral coefficients and the frequency masking characteristics of the human auditory system. The proposed watermark embedding scheme minimizes audibility of the watermark signal. and the embedded watermark is robust to mu1tip1e watermarks, MPEG audio ceding and additive noose.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.1-10
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• 2017

Sudden natural disasters such as earthquakes, typhoons, heavy rainfall, etc., which come without warning, often threaten our lives and property, so it is important to spread the disaster quickly and accurately. Thus, in this paper, we present a method for the activating of FM radio receiver chip embedded in smartphone to receive disaster broadcasting in case of disaster. One is to investigate the roles and limits in a domestic disaster broadcasting system and disaster relay broadcasting by media, and the other is to present the method for the activation of smartphone FM radio receiver chip by conduct an expert survey.

• Science of Emotion and Sensibility
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• v.15 no.4
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• pp.517-526
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• 2012

This study investigated the impact of individual differences in motivational reactivity on cognitive effort, memory strength (sensitivity) and decision making (criterion bias) in response to Internet ads with positive and negative content. Individual variation in trait motivational activation was measured using the Motivational Activation Measurement developed by A. Lang and her colleagues (A. Lang, Bradley, Sparks, & Lee, 2007). MAM indexes an individual's tendency to approach pleasant stimuli (ASA, Appetitive System Activation) and avoid unpleasant stimuli (DSA, Defensive System Activation). Results showed that individuals higher in ASA exert more cognitive effort during positive ads than individuals lower in ASA. Individuals higher in DSA exert more cognitive effort during negative ads compared to individuals lower in DSA. ASA did not predict recognition memory. However, individuals higher in DSA recognized ads better than those lower in DSA. The criterion bias data revealed participants higher in ASA had more conservative decision criterion, compared to participants lower in ASA. Individuals higher in DSA also showed more conservative decision criterion compared to individuals lower in DSA. The theoretical and practical implications are discussed.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.30-36
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• 2013

Recently the globalization of the media content industry, various activities have been made in the field of art and the speaker system is very important in the sound industry which is one of the arts. The directional characteristics of a loudspeaker refer to the radiation of sound in certain directions and are among the most important features of a loudspeaker. Designing a loudspeaker that can keep all of its constant directivity at all frequencies is difficult due to the wavelengths of audio frequencies and the size of horns and transducers. This study proposed gradient array methods to improve low frequency pattern control of full-range speakers to maximize Direct to Reverberant Ratios at the listeners.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.107-113
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• 2017

Recently, digital signage is various changes and converging media. It is common to exhibit and guide focusing on information transfer by using the display. Such a method can not express variously changing digital signage. Therefore, we have to find a way to solve the problem of place and structure. In this paper, we experimented the new direction technique. Finally, we are going to propose acoustic direction technique using a microphone to maximize digital signage and intention of delivery by adding an sound reinforcement method to the visual representation.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.356-366
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• 2008

In the past, design used to be known as graphic design for printing medium. However, these days, through video media or multimedia, it has expanded to convey information thanks to the innovative development of the computer, which is digital civilization. Now design, through elaborate plans and projects, is acknowledged as creative work for communications appealing to emotion comprehensively and to transmit information effectively. This thesis presented a new methodology of mess communication using various elements such as video typography. Furthermore, reflecting feedback from hearing-unpaired people, theological background well grounded and the way to proceed in the future were also addressed.