• 전자공학회논문지 IE
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• v.47 no.3
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• pp.35-40
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• 2010

In this paper, we propose an algorithm to improve the precision of initial carrier-frequency offset estimation for multiband-OFDM (MB-OFDM) UWB system which is considering the quantization-noise effect. In the general OFDM system, the two adjacent and repeated preamble symbols are used for the initial carrier-frequency synchronization while the performance of the frequency-offset estimation is bounded by quantization effect generated from analog-to-digital conversion at the receiver. This paper proposes a method in which one-symbol interval between two adjacent preamble symbols for the initial frequency synchronization is extended to multiple-symbol interval between non-adjacent symbols in an extent that phase ambiguity does not occur. In this paper, we also present '6' as optimal multiple symbol interval for the MB-OFDM system with 30 preamble symbols on 3-band hopping and with 4-bit A/D conversion at the receiver. Under the channel environments for the MB-OFDM UWB system, the simulation results show that the proposed estimation algorithm can achieve the initial estimation in offset precision less than 5 ppm.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.26 no.2
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• pp.129-153
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• 2015

This research reviews literature regarding information use behavior published during the period of 1970 to 2014 in Korea. It aims to identify the researchers' information use behavior in specialized fields and contributes to provide the effective information services based on users' needs. In order to do that, it reviews research papers that are associated with information use behavior by primarily examining the subjects, methods, variables, results, and suggestions of collected literature. It reveals some differences among researchers according to their fields, career, and status while researchers in various fields make appearance the change of information use up to digital environments. It is suggested that information services based on the users' characteristics should be provided.

• Journal of Korea Game Society
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• v.15 no.4
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• pp.121-132
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• 2015

This study suggests a design for an analytical software program and method for multitasking e-sports viewing through the web using an eye tracking device. To fulfill this task, we designed a Window of Interest (WOI) to measure and record visually on a screen wherever numerous multitasking activities occur. In addition, we developed an OBS (Opensource Broadcaster Software) plug-in that records and streams participant viewing behavior patterns in real time. The purpose of this study is as follows. First, unlike existing tools that limit web interface recording to still images, the developed tool can record dynamically via media such as videos. Second, when several windows are processed on a screen, the tool can accurately record the gaze positions of the participants. Lastly, the tool can enhance the objective validity of the data as it can be implemented in natural situations. Therefore, this study can trace natural viewing patterns and behavior as we do not create artificial experimental environments and stimuli.

• Journal of Korea Game Society
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• v.14 no.5
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• pp.7-14
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• 2014

Since educational and fun elements coexist in an educational game, it is important to come up with standards that can elicit fun with the game as well as educational standards. Many of the existing developed educational games have received low marks in the characteristics of entertainment and game design. Thus, how to make up for their entertainment characteristics is important. This paper analyzes gaming elements of puzzle games that were released for smart phones and gained massive popularity from their users and will apply them to educational games. Such games that have gained popularity and won a commercial success include Anipang, Anipang 2, Candy Crush Saga, Farm Heroes Saga and Pokopang. This study will analyze gaming elements of these games. By analyzing the educational games, it is applied to the game elements of casual games. In addition, we have proposed a element that can enhance the immersive. Game design elements that can improve entertainment characteristics include game rules, stages and missions. Elements that can increase immersion include items, background maps and new learning environments. This paper has significance in that it analyzes entertainment characteristics, which mean the fun of games through those that have been a commercial success and applies them to educational games.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.35.1-35.1
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• 2016

Nearby galaxy clusters and their surrounding regions represent the current endpoint of evolution galaxy cluster evolution. We present a new catalog of 1589 galaxies, what we call Extended Virgo Cluster Catalog (EVCC), in wider area of the Virgo cluster based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The EVCC covers an area 5.2 times larger than the footprint of the classical Virgo Cluster Catalog, and reaches out to 3.5 times the virial radius of the Virgo cluster. The EVCC contains fundamental information such as membership, morphology, and photometric parameters of galaxies. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths. We also present the large scale structures in the field around the Virgo cluster. We identified seven galaxy filaments and one possible sheet in three dimensions of super-galactic coordinates based on the HyperLEDA database. By examining spatial distribution and Hubble diagram of galaxies, we found that six filaments are directly associated with the main body of the Virgo cluster. On the other hand, one filament and one sheet are structures located at background of the main body of Virgo cluster. The EVCC and the filament structures will be the foundation for forthcoming studies of galaxy evolution in various environments as well as buildup of the galaxy cluster at z ~ 0, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1867-1872
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• 2016

In the area of digital signal processing, it is necessary to improve the quality of the speech signal after removing the background noise which exists in a various real environments. The important thing to consider when removing the background noise acoustically is that to solve the problem, depending on the information of the human auditory mechanism is mainly the amplitude spectrum of the speech signal. This paper introduces the characteristics of a frequency-weighted spectrum shaping filter for the extraction of the amplitude spectrum of the speech signal with the primary purpose. Therefore, this paper proposes an algorithm using the methods of a Wiener filter and the frequency-weighted spectrum shaping filter according to the acoustic model, after extracted the amplitude spectral information in the noisy speech signal. The spectral distortion (SD) output of the proposed algorithm is experimentally improved more than 5.28 dB compared to a conventional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.9
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• pp.728-737
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• 2012

An analytical method for identifying terrestrial broadcasting coverages is proposed for a terrestrial broadcasting transmission system adopting a hierarchical modulation technique. Bit Error Rates(BERs) are derived for hierarchically modulated non-uniform QAM constellations based on the Q-function analysis in AWGN environments. The derived BERs depend on the hierarchical modulation factor ${\alpha}$(HMF) and could be mapped to the broadcasting coverages according to the link budget analysis based on the log-distance path loss model. Finally the broadcasting coverage ratios for high priority(HP) streams and low priority(LP) streams are calculated and presented for the determination of the HMF.

• Archives of design research
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• v.15 no.3
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• pp.271-280
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• 2002

These days information technology and internet have made startling progress. In these developing environments, the strategy or marketing based on existing off-line is getting more difficult to accomplish the role of the improvement of business competitive power, and they are bringing out a lot of changes in information management and marketing performance method about consumers due to digital networking between companies and consumers. These developments and changes make many varieties in the way of design studying methodology. Therefore, in this study, considering the aspects of design, society and environment, after I developed the consumer response framework about products design which is argued by Bloch(1995) ; distinct relationship model among preference degree- design image adjective - design factors, we established design information abstraction solution combined with the interaction based on IT as eCRM in real time. This suggested solutions will provide product designers with good information in finding the design factors which consumers prefer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1854-1863
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• 2003

In the recent digital communication systems, the performance of Turbo Code using the mr correction coding depends on the interleaver influencing the free distance determination and the recursive decoding algorithms that is executed in the huh decoder. However, performance depends on the interleaver depth that needs many delays over the reception process. Moreover, turbo code has been blown as the robust coding methods with the confidence over the fading channel. International Telecommunication Union(ITU) has recently adopted it as the standardization of the channel coding over the third generation mobile communications(IMT­2000). Therefore, in this paper, we preposed the interleaver that has the better performance than existing block interleaver, and modified turbo decoder that has the parallel concatenated structure using MAP algorithm. In the real­time voice and video service over third generation mobile communications, the performance of the proposed two methods was analyzed and compared with the existing methods by computer simulation in terms of reduced decoding delay using the variable decoding method over AWGN and fading channels for CDMA environments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.113-118
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• 2006

Recently, wireless LANs are often applied in home or office because of its various of convenience. Frequency rage of wireless LANs specified by IEEE 802.11b is at 2.4 GHz. The bluetooth, the microwave oven, and the PDA(Personal Digital Assistants) uses ,however, the same frequency band. So problems will be produced in these environments, such as multi-pass interference and system-to-system interference. These problems can be eliminated by using EM wave absorber. In this paper, we designed and fabricated EM wave absorber using Sendust, $Al(OH)_3$, and CPE. The double-layered EM wave absorber with thickness of 1.5 mm has absorption ability more than 10 dB at 2.4 GHz.