• Journal of Korea Spatial Information System Society
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• v.3 no.1 s.5
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• pp.117-126
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• 2001

We have developed the Mobile Multi Sensor System(MMSS) for the data construction of 4S application and for basic technology acquisition of mobile mapping system in Korea. Using this MMSS, we will collect the information of road and road facilities for DB creation and also construct the Digital Elevation Model(DEM) as ancillary data in urban area. The MMSS consist of the integrated navigation sensor, DGPS & IMU, and digital CCD camera set. In the S/W aspect, we developed the post-processing components for extracting the 3D coordinate information (Spatial Information) and the client program for the MMSS user group. In this paper, we will overview the MMSS constitution and post-processing program, and introduce the utilization plan of MMSS.

• 한국지형공간정보학회:학술대회논문집
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• 2001.11a
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• pp.9-13
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• 2001

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.127-130
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• 2015

ITU-R has conducted a studies for the frequency allocation to the maritime mobile satellite service (MMSS) in the 7375 - 7750 / 8025 - 8400 MHz under WRC-15 agenda item 1.9.2. In order to allocate a certain frequency bands to the new service, compatibility between new service and the existing services is ensured taking into account protecting the existing services form interference of new service. In this paper, we present current studies results of the frequency sharing studies between new allocation to MMSS and the existing services in the ITU-R. In addition, some proposals for allocating the 7/8 GHz frequency bands to MMSS are also considered for efficient spectral utilization with respect to preparing WRC-15.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.180-186
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• 2004

The presence of noise in speech signals degrades the performance of recognition systems in which there are mismatches between the training and test environments. To make a speech recognizer robust, it is necessary to compensate these mismatches. In this paper, we studied about an improvement of stochastic feature extraction based on band-SNR for robust speech recognition. At first, we proposed a modified version of the multi-band spectral subtraction (MSS) method which adjusts the subtraction level of noise spectrum according to band-SNR. In the proposed method referred as M-MSS, a noise normalization factor was newly introduced to finely control the over-estimation factor depending on the band-SNR. Also, we modified the architecture of the stochastic feature extraction (SFE) method. We could get a better performance when the spectral subtraction was applied in the power spectrum domain than in the mel-scale domain. This method is denoted as M-SFE. Last, we applied the M-MSS method to the modified stochastic feature extraction structure, which is denoted as the MMSS-MSFE method. The proposed methods were evaluated on isolated word recognition under various noise environments. The average error rates of the M-MSS, M-SFE, and MMSS-MSFE methods over the ordinary spectral subtraction (SS) method were reduced by 18.6%, 15.1%, and 33.9%, respectively. From these results, we can conclude that the proposed methods provide good candidates for robust feature extraction in the noisy speech recognition.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.187-195
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• 2020

Although multimedia messaging services (MMS) are becoming increasingly popular, and companies are maximizing the use of their content, few systematic studies on MMSs exist. This study examined technology acceptance factors for MMS in 398 young people aged 10 to 39 to identify MMS users' continuous intention to use (CITU) via a questionnaire and SPSS21 and PLS-Graph 3.0. The results showed that perceived media richness (PMR) had a positive effect on perceived usefulness, perceived ease of use, and most importantly, CITU. Furthermore, PMR had a positive effect on perceived ease of use as a moderating effect on experience. To increase use efficiency in MMSs based on these results, media richness, perceived ease of use, perceived usefulness, and user experience may serve as important variables affecting users' CITU and provide a basic reference and development direction for MMS users. Future studies should include more variables and examine additional factors when analyzing the structural model.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.287-296
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• 2014

Given rapid growth of mobile messenger services (MMSs) such as KakaoTalk, Line, and Wechat, it has become critical to understand the mechanisms that lead to user loyalty in the MMS context. In this regard, this study examined key factors of user loyalty in the MMS environment. We posit attitudinal loyalty and IT expertise as key drivers of behavioral loyalty. In addition, the impacts of perceived usefulness and emotion on attitudinal loyalty were examined. Data collected from 235 KakaoTalk users who have used more than 1 year were empirically tested against a research model using partial least squares. The analysis results found that both attitudinal loyalty and IT expertise play an important role in enhancing behavioral loyalty in the MMS context. The findings of this study indicate that perceived usefulness and positive emotion significantly influence attitudinal loyalty, whereas negative emotion negatively affects it. The analysis results provide several insights that can help MMS providers understand the role of emotion in enhancing user loyalty.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.241-251
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• 2014

Mobile messenger services (MMSs), such as Kakaotalk, Wetalk, Line, and Whatsapp, are gaining popularity worldwide because of communicating with other people without any cost. We examined key antecedents of user loyalty to understand user's decision-making process in the MMS environment. To capture a long-term relationship with service providers, we posit relational commitment and user satisfaction as key predictors of user loyalty. Moreover, the effects of perceived usefulness, perceived enjoyment, and corporate image on user's decision-making processes were examined. The proposed model was tested by applying partial least squares to data from 220 experienced Kakaotalk users. The findings of this study found that both relational commitment and user satisfaction play an important role in enhancing user loyalty in the MMS context. The analysis results indicate that corporate image influences relational commitment and user loyalty through user satisfaction. The analysis results help MMS providers establish management or marketing strategies to effectively improve user loyalty.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.41-46
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• 2013

In this paper, we present the compatibility study results including the frequency sharing criteria between new allocation to maritime mobile satellite service and Earth exploration satellite service in the 7/8 GHz. The transmitting Earths station of MMSS in the 8025 - 8400 MHz band would make harmful interference to the receiving Earth station of EESS operating in the same frequency band. In order to ensure the compatibility with EESS, the separation distance is provided as a frequency sharing criteria. The republic of Korea has a plan to launch the geostationary satellite around 2017 and EESS Earth station will be operated in 8025 - 8400 MHz band. Therefore, we calculate the interference levels and separation distance using the system parameters of two Earth station systems. As results of the study, the separation distances for LOS path and Non-LOS path due to the geographical characteristics are shown around 471 km and 200 km, respectively.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.131-139
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• 2016

Given social problems of service addiction such as mobile messenger services(MMSs), many studies on service management and information systems have examined the negative outcomes of service addiction. MMS addiction significantly influences user's health and academic performance. In this regard, this study investigated the effects of MMS addiction on user's health and academic performance problems. We posit personal traits and service features as key antecedents of MMS addiction. The research framework was tested by using survey data collected from 162 university students who have frequently used Kakaotalk. The analysis results found that MMS addiction significantly influences users' health and academic performance problems. The findings of this study indicate that self-esteem and self-control play an important role in generating MMS addiction. While attention significantly affects MMS addiction, social relationship formation and perceived enjoyment are not significantly associated with MMS addiction. The analysis results help MMS providers and government establish policies or guidelines to induce healthy MMS use.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.95-103
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• 2014

Given social problems of technology addiction such as games and mobile messenger services (MMSs), it have become important to understand theoretical mechanisms to generate technology addiction. In this vein, this study examined key antecedents of technology addiction in the MMS environment. We posit technology habit and user satisfaction as key predictors of technology addiction. In addition, the impacts of social interaction and flow on use's technology addition formation were investigated The research framework was tested by using survey data collected from 278 Kakaotalk users who have used more than 6 months. The analysis results found that both technology habit and user satisfaction play an important role in generating technology addiction in the MMS context. The findings of this study indicate that social interaction and flow significantly affects technology habit and user satisfaction. The analysis results help government and MMS providers establish policies or strategies to induce healthy MMS use.