• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.905-910
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• 2010

In this paper, visible light communication(VLC) system modulated by a switching driver circuit of lighting light emitting diode(LED), not only for illumination but also for optical wireless communication, is implemented. Presented system could overcome the drawbacks of prior linear modulation technique such as low efficiency, heat generation, and limits to realization of high power lighting LED. Experimental results from the realized digital audio system are presented to confirm the superiority of the proposed circuit. Our prototype achieves a transmission data rate of 10 Mbps with a radius of 1.5 meters using 20 W output power, and the signals were detected successfully.

• Archives of design research
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• v.17 no.2
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• pp.393-402
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• 2004

The mobile advertisement has varied on lifestyle of people, who live aninformation-oriented society with portable equipment such as web phone and PDA(Personal Digital Assistant). Also, the advertising has expended mobile techniques and its application field unpredictably. The intrinsic characteristic of misdistribution, reach, and convenience in mobile advertisement add up the capacity of a location, information and individualize. This market condition leads the basic audio focused formal mobile advertisement to the new mobile Internet environment with an additional able of data communication. Moreover, the type of SMS (Short Message Service), Graphic, Wep Push, and ridchmedia, which based on music, basic graphic, voice, and letters transfer by mobile terminal and the mobile character is present inevitably correlation with pixel art and animation in 2D(Two Dimensions) techniques. Thus, this research appoints the importance and its role of mobile advertisement that is core of the business marketing in new media era. To activate mobile market, the mobile companies classify the characteristic of consumers with developed commercial use of mobile character and research their behavior to meet optimal mobile character in business.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1211-1219
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• 1999

High quality real-time interactive multimedia services like VOD gained huge momentum by information technology industries during the middle of 1990, but failed successful commercial service deployment despite of the expectations. Among the number of reasons, lack of high bandwidth and QoS support from the network infrastructure have become main cause of the failure. On the other hand, the advance of computer industry-driven storage technologies has been reducing the price of in-home storage dramatically. This fact and the delivery of audio-visual material in a digital form to the home storage make very interesting multimedia service applications possible. It enables anytime content delivery (e.g., during off-peak time) without user interaction and anytime content play and, also, enhances utilization by reducing the loads applied to servers and networks using multicast network infrastructure. In this paper, we propose design and implementation of our anytime multimedia service system based on in-home storage, called IMPRESS-AMS.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1476-1484
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• 1999

TV 방송 분야에서 다양한 정보와 상호 작용성을 제공하기 위해서 최근 기존 방송 내용인 A/V 스트림 외 부가정보 방송이 시도되고 있다. 데이타 방송에 대한 기존 연구는 대부분 고정된 내용의 데이타를 방송하는 환경을 가정하고 있어서 그 결과가 방송 내용의 변화가 많은 환경에 부적합하다. 본 논문에서는 데이타에 대한 접근이 반복되지 않을 가능성이 높고 사용자 접근 확률을 예상하기 어려운 상황에서 응답 시간을 개선하는 방안으로 수신 데이타를 무조건 캐쉬에 반입하고 교체가 필요한 경우 다음 방송 시각이 가장 가까운 페이지를 축출하는 사용자 단말 시스템에서의 캐슁 정책을 제안하였다. 제안된 캐쉬 관리 정책은 평균적인 캐쉬 접근 실패 비용을 줄임으로써 사용자 응답 시간을 개선하며, 서로 다른 스케줄링 기법을 사용하는 다양한 방송 제공자가 공존하는 환경에서 보편적으로 효과를 가져올 수 있다.Abstract Recently, many television broadcasters have tried to disseminate digital multimedia data in addition to the traditional content (audio-visual stream). The broadcast data need to be cached by a client system, to provide a reasonable response time for a user request. Previous studies assumed the dissemination of a fixed set of items, and the results are not suitable when broadcast items are frequently changed. In this paper, we propose a novel cache management scheme that chooses the replacement victim based on the remaining time to the next broadcast instance. The proposed scheme reduces response time, where it is hard to predict the probability distribution of user accesses. The caching policy we present here significantly reduces expected response time by minimizing expected cache miss penalty, and can be applied without difficulty to different scheduling algorithms.

• Journal of Korean Library and Information Science Society
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• v.49 no.1
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• pp.193-214
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• 2018

This study aimed to exploratorily investigate the new roles of libraries in the era of K-MOOC. For this, potential roles were derived and categorized from former researches and practices. And to evaluate the appropriacy of those roles, two expert surveys were conducted. Panel A was comprised of 30 professors who had been running K-MOOC classes and Panel B was comprised of 30 librarians of Universities that had adopted K-MOOC. The result shows that they both agree about distinct roles of library as information provider such as licensing and providing digital contents requested from information users, while technological part, for example, recording video and audio, managing website, and providing open access, was considered inappropriate because those roles were already taken by CTLs. Also, professors agree that information literacy education is required for teachers not just for students as the speed of technological development is too swift and librarians agree that they have to equipped with core competence in preparation for upcoming change by creating added value, establishing closer relationship with various educational and technological institutes, and securing organizational flexibility.

• Journal of the Korean School Mathematics Society
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• v.15 no.3
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• pp.565-584
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• 2012

This study investigates how the GSP helps gifted and talented students understand geometric principles and concepts during the inquiry process in the generalization of the internal triangle, and how the students logically proceeded to visualize the content during the process of generalization. Four mathematically gifted students were chosen for the study. They investigated the pattern between the area of the original triangle and the area of the internal triangle with the ratio of each sides on m:n respectively. Digital audio, video and written data were collected and analyzed. From the analysis the researcher found four results. First, the visualization used the GSP helps the students to understand the geometric principles and concepts intuitively. Second, the GSP helps the students to develop their inductive reasoning skills by proving the various cases. Third, the lessons used GSP increases interest in apathetic students and improves their mathematical communication and self-efficiency.

• Journal of Broadcast Engineering
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• v.17 no.3
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• pp.529-539
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• 2012

Testing is an important part of quality control in the software life cycle. One of the most important issues in the software testing is to generate the appropriate test cases. Generally, the software can be tested based on product understanding. However, it is not easy to create test cases that can ensure the quality of the software according to the clients' request. Especially, it is difficult to create test cases for abnormal or exceptional situations. In this paper, we present a novel approach to generate exceptional test cases at the design level of UML model. Furthermore, we describe the results of actual experiment where DAB(Digital Audio Broadcasting) parsing program is tested with previous method and also with the proposed method. The results implies that our proposed method of generating test cases for exceptional situations detect more faults than that of previous method by 7.08%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1051-1066
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• 2000

According to the recent advances of digital encoding technologies and computing power, large amounts of multimedia informations such as image, graphic, audio and video are fully used in multimedia systems through Internet. By this, diverse retrieval mechanisms are required for users to search dedicated informations stored in multimedia systems, and especially it is preferred to use contents-based retrieval method rather than text-type keyword retrieval method. In this paper, we propose a new contents-based indexing and searching algorithm which aims to get both high efficiency and high retrieval performance. To achieve these objectives, firstly the proposed algorithm classifies images by a pre-processing process of edge extraction, range division, and multiple filtering, and secondly it searches the target images using spatial and textural characteristics of colors, which are extracted from the previous process, in a image. In addition, we describe the simulation results of search requests and retrieval outputs for several images of company's trade-mark using the proposed contents-based retrieval algorithm based on wavelet.

• Journal of Korea Multimedia Society
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• v.14 no.11
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• pp.1431-1437
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• 2011

This paper proposes a novel watermarking algorithm that protects digital copyrights and is robust to attacks. Watermarks are embedded in the subband including the significant part of the signal such as a pitch. Generally, the subband containing the pitch has the biggest energy. In order to find this subband, wavelet packet transform is used to decompose the subbands and their energy are calculated. The signal of the selected subbands is transformed in frequency domain using FFT. The watermarks are embedded using QIM for samples higher than a certain threshold. The blind detection uses the Euclidean distance. The proposed method shows less than 5% BER in the audio watermark benchmarking.

• Journal of Broadcast Engineering
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• v.11 no.4 s.33
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• pp.541-553
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• 2006

Since DMB on-air was started, not high-qualified audio, video services but various service models have been required. This paper is about systems for one of these services, video associated data service. A terrestrial DMB system to make contents of video associated data services and transmit them on DMB channel is proposed in this paper. This system satisfies standard of the video associated data services for terrestrial DMB; MPEG-4 BIFS (BInary Format for Scene) Core2D scene description profile and graphics profile. This system is designed to support two major features of broadcasting, real-time authoring non automatic transmission and non real-time authoring automatic transmission, and focuses on the abilities to make high-qualified contents efficiently and transmit them to video encoder reliably. This system proved its performance through conformance tests with various receivers, so can be used in future on-air.