• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.172-178
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• 2011

In this paper, the performance of bit interleaved of coded and modulation(BICM) module of the second generation of digital terrestrial television broadcasting system(DVB-T2) is evaluated with the help of computer simulation. The frame error rate performance is studied in AWGN, Rayleigh fading and 15% erasure channels. In addition, iterative receiver is considered that exchanges extrinsic information between the rotated demapper and the LDPC decoder. Through the simulation it is observed that under the flat fading Rayleigh channel, about 1.2dB gain at FER of $10^{-4}$ is introduced when rotated constellation and iterative demapping and decoding are employed. Under the 15% earasure channel, rotated constellation gives performance gain of about 5dB at BER of $10^{-4}$ and when IDD is applied, additional performance gain of about 3dB can be achieved.

• Korean journal of communication and information
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• v.29
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• pp.111-145
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• 2005

In this study, the problems In the current HDTV programming strategies were critically inquired into and reform measures were sought through in-depth interview with HDTV programming staff and program directors of the three major terrestrial broadcasting systems that are in their fourth year of HDTV broadcasting, and through analysis of the characteristics of HDTV programming. The analysis of this study showed that the time allocated to HDTV programs far exceeded the thirteen hours per week set by the Korean Broadcasting Commission. However, the percentage of HDTV programs broadcasted during the prime time was low, which as a result, limited the opportunity for the audiences to experience HDTV. furthermore, the low percentage of programs such as documentaries, sports, movies, etc. that are preferred by early adopters and through which the features of HDTV including high quality of picture, wide screen, etc. can be fully applied and shown did not appear to help in accelerating the popularization of HDTV In order to improve these problems, despite their having to bear the initial production costs, the broadcasting systems must come up with an aggressive strategies for the programming of documentaries, sports programs and dramas in order to strengthen the competitiveness in HDTV production and secure future adopters, and together with this, full support from the policy planning authorities and companies manufacturing electric home appliances, the other leaders in DTTB(Digital Terrestrial Television Broadcasting) transition, are necessary in order to promote the production of HD contents.

• Korean Journal of Optics and Photonics
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• v.22 no.4
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• pp.191-197
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• 2011

In this paper, we have designed an integrated triplexer which is the basic component for a FTTH(Fiber To The Home) system which can transmit CATV and voice/data at the same time in a single fiber. The integrated triplexer can be fabricated with a novel technique of "Micro-Block Stacking (MBS)" method which automatically aligns the optical components in the optical beam pass using accurate ceramic holders. We analyze the displacement of the optical focus according to the tolerances of the component dimensions and the assembly process using code V simulator. For the transmitter, the most serious shift of the focal points is caused by the displacements of the LD spot. So the focal point moves up to $72{\mu}m$ from the center point for ${\pm}25{\mu}m$, ${\pm}25{\mu}m$, ${\pm}30{\mu}m$ displacements. For the receiver the most serious shift of the focal points is caused by the displacements of a 0.8mm ball lens (for the analog receiving part) and a micro ball lens (for the digital receiving part), and the focal point moves up to $55{\mu}$ for ${\pm}55{\mu}m$, ${\pm}5{\mu}m$, ${\pm}55{\mu}m$ micro ball lens displacements.

• Cartoon and Animation Studies
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• s.41
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• pp.487-510
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• 2015

In recently, thanks to the development of computer and internet, and reinforcement of digital media literacy of ordinary people, many users of comics and animations recombine contents into various ways, including UCCs. In a glance, it seems these outputs violates the copyrights of contents. But in reality, they helps the growth of the ecosystem of contents market, with increase of contents users. The reason of these reproductions inclines the characteristics of animation media. Animation, which are constituted by plastic symbols, auditory symbols, and narrative symbols, and Comic, which supports stories of Animations, affects as 'Imaginary signifier'. These signifiers helps users of contents to dismantle and reassemble stories. These aspects are seen in doujin culture, animation soundtrack fandom, and voice actor fandom. But In this article, we will concentrate into cosplay culture. Cosplay culture shows more active appearances than another fandoms. In especially, cosplay stage and daily cafe show more active reproductions of characters and communications. However, they are done by youth fans, which has not enough financial abilities: therefore, events are not sustainable and discontinued. And they have another limits, like lack of opportunity of performance. In the reality of Korean society, which needs of community making by community member, and hybrid culture, comics and animation productions in Korea are in need of access positively and encourage reproductions of active receivers of animations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.4
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• pp.428-435
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• 2004

With the rapid and wide-spread use of cellular telephones much attention has been focussed on propagation in the urban area crowed with buildings and houses. It is often surrounded by hills, forests, and mountains. The importance of surface scattering intereference between transmitters and receivers on the rough surfaces has been interested and investigated. Therefore, a prediction method is necessary to estimate the influence of rough surfaces on microwave radio propagation. Moreover, most of the mobile communications are performed based on the digital communication system rather than the analog one. In this case, we must pay more careful attention to the signal delay caused by the phase delay due to the multi-path propagation. In this paper we have analyzed numerically scattering of electromagnetic waves from building walls by using FVTD(Finite Volume Time Domain) method. We consider three different types of rough surfaces such as periodic, random, and composite structures. We calculate the bistatic normalized radar cross section (NRCS) for horizontal and vertical polarization, and we take account of the conventional optical reflection which corresponds to the n-th Bragg reflection for periodic structures. In addition, we investigated what conditions are needed in order to be able to ignore the higher order Bragg reflection for the periodic structures.

• Journal of the Korean Geographical Society
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• v.48 no.2
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• pp.259-271
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• 2013

This paper addresses the efficient facility placements to adopt a super WiFi network, taking significant considerations as the next generation 'information highway'. Since the super WiFi has a wider geographic coverage by utilizing the white spaces of TV broadcasting which are empty and available frequencies for the wireless communications, it would play an important role in releasing digital divide of the internet access for low populated or mountainous areas. The purpose of this paper is to explore systematic and efficient spatial plans for the super WiFi. For doing this, we applied optimal location covering models to Gurye-gun, Jeonlanamdo. From the application, we presented optimal locations for super WiFi facilities and significant analytical results, such as the tradeoff between the number of facilities and coverage and marginal coverage for establishing super WiFi network. The results of this research would be usefully utilized for decision makers who wish to adopt a super WiFi, to extend wireless networks in a city or build a regional infrastructure of wireless facilities.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.243-246
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• 2013

Recently, the 4th generation of mobile communications in Korea with anyone supports was supported high speed multimedia communication services. With the launch of Apple iPhone, there is an explosion of interest in Smartphone itself as well as Internet-based services using Smartphone are being revitalized. Smartphone users, opinion experts almost of the economically active population is using, it has reached the saturation past the early stages of formation. In 1989, the 1st generation mobile communication service has been started with the analog voice service. After this, the 2nd generation mobile communication service for short messages and digital voices has been developed. And, the 3rd generation service of low speed data and low quality videos has been realized in 2000s. The very high speed data service of LTE (long term evolution), which is the 4th generation mobile communication service standards, had been in July 2011. and the subscribers are increasing constantly. However, changes in communication technology, has given an economical cost to Smartphone users. Therefore, the purposes of this study was trending of the communication cost according to the change in the communication technology of the mobile communication industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1460-1468
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• 2000

The goal of this research is the real-time implementation of MPEG-1 Layer III audio decoder using the fixed-point digital signal processor of TMS320C6201 The main job for this work is twofold: one is to convert floating-point operation in the decoder into fixed-point operation while maintaining the high resolution, and the other is to optimize the program to make it run in real-time with memory size as small as possible. We, especially, devote much time to the descaling module in the decoder for conversion of floating-point operation into fixed-point operation with high accuracy. The inverse modified cosine transform(IMDCT) and synthesis polyphase filter bank modules are optimized in order to reduce the amount of computation and memory size. After the optimization process, in this paper, the implemented decoder uses about 26% of maximum computation capacity of TMS320C6201. The program memory, data ROM, data RAM used in the decoder are about 6.77kwords, 3.13 kwords and 9.94 kwords, respectively. Comparing the PCM output of fixed-point computation with that of floating-point computation, we achieve the signal-to-noise ratio of more than 60 dB. A real-time operation is demonstrated on the PC using the sound I/O and host communication functions in the EVM board.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.683-694
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• 2002

In this paper, a digital image compression codec using 2D DWT(Discrete Wavelet Transform) is designed using the FPGA technology for real time operation The implemented image compression codec using wavelet decomposition consists of a wavelet kernel part for wavelet filtering process, a quantizer/huffman coder for quantization and huffman encoding of wavelet coefficients, a memory controller for interface with external memories, a input interface to process image pixels from A/D converter, a output interface for reconstructing huffman codes, which has irregular bit size, into 32-bit data having regular size data, a memory-kernel buffer to arrage data for real time process, a PCI interface part, and some modules for setting timing between each modules. Since the memory mapping method which converts read process of column-direction into read process of the row-direction is used, the read process in the vertical-direction wavelet decomposition is very efficiently processed. Global operation of wavelet codec is synchronized with the field signal of A/D converter. The global hardware process pipeline operation as the unit of field and each field and each field operation is classified as decomposition levels of wavelet transform. The implemented hardware used FPGA hardware resource of 11119(45%) LAB and 28352(9％) ESB in FPGA device of APEX20KC EP20k600CB652-7 and mapped into one FPGA without additional external logic. Also it can process 33 frames(66 fields) per second, so real-time image compression is possible.

• Communications of Mathematical Education
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• v.23 no.1
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• pp.145-174
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• 2009

Based on the thinking that people can understand more clearly when the problem is related with their prior knowledge, the Purpose of this study was to analysis students' informal knowledge, which is constructed through their mathematical experience in the context of real-world situations. According to this purpose, the following research questions were. 1) What is the characteristics of students' informal knowledge about fraction before formal fraction instruction in school? 2) What is the difference of informal knowledge of fraction according to reasoning ability and grade. To investigate these questions, 18 children of first, second and third grade(6 children per each grade) in C elementary school were selected. Among the various concept of fraction, part-whole fraction, quotient fraction, ratio fraction and measure fraction were selected for the interview. I recorded the interview on digital camera, drew up a protocol about interview contents, and analyzed and discussed them after numbering and comment. The conclusions are as follows: First, students already constructed informal knowledge before they learned formal knowledge about fraction. Among students' informal knowledge they knew correct concepts based on formal knowledge, but they also have ideas that would lead to misconceptions. Second, the informal knowledge constructed by children were different according to grade. This is because the informal knowledge is influenced by various experience on learning and everyday life. And the students having higher reasoning ability represented higher levels of knowledge. Third, because children are using informal knowledge from everyday life to learn formal knowledge, we should use these informal knowledge to instruct more efficiently.