• Proceedings of the Korean Society of Computer Information Conference
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• 2018.01a
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• pp.193-194
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• 2018

미디어 서비스는 사용자들의 다양한 미디어 소비 패턴 변화와 상호작용 서비스, 고화질 고용량의 다양한 소비자들 요구로 인해 새로운 미디어 서비스 패러다임을 맞이하고 있다. 이에 따라, IT 자원의 효율적인 사용 및 유지 관리비용의 절감을 목적으로 클라우드 컴퓨팅을 기반으로 한 클라우드 미디어 서비스의 연구가 활발히 이루어지고 있다. 하지만, 기존 클라우드 기반 미디어 서비스의 경우 저작권 보호 기술이 제한적이며, 사용자 및 서비스 제공자에게 유연한 저작권 보호 기술이 필요하게 되었다. 본 논문에서는 클라우드 기반 미디어 서비스를 위한 저작권 보호 플랫폼에 대한 참조 모델을 제시하여 멀티 DRM을 지원하는 클라우드 기반 미디어 서비스를 구축할 때 실제 시스템 구현에 참조할 수 있는 모델을 제시한다.

• The Journal of Information Systems
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• v.21 no.4
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• pp.81-108
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• 2012

Growth in the device field is driven by various emerging devices, tablet PC are among the most recognizable. Tablet PC are mobile computing devices enabled with touch screens or pen inputs and provide the functions of various other devices. Firms are interested in utilization of tablet PC on task. Many of firms is considering accepting of tablet PC and is looking forward to performance of tablet PC. Thus, this study propose to discuss strategies for the usage of tablet PC from organizational needs perspective. The goal of this study is to identify factors influencing use of tablet PC and task performance. The results of this study showed that the proposed factors of organizational needs with a exception of Service Flexibility had a positive impact on perceived usefulness that then positively affected Usage of Tablet PC and Task Performance. In addition, perceived task-technology fit had a positive impact on perceived usefulness and Usage of Tablet PC. Finally, Innovative Culture of Organization as a moderating effect significantly influenced the relationship between perceived usefulness, perceived Task-Technology Fit and Usage of Tablet PC. This study is expected to be a reference for a subsequent study associated with Tablet PC at organizational viewpoints.

• The Journal of Information Systems
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• v.21 no.1
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• pp.93-116
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• 2012

Internet users' desire to share shopping experiences has resulted in the appearance of the paradigm shift called social commerce, which combines social media with commerce. However, while foreign market realizes social commerce in a various way, current domestic social commerce market still seems to be highly filled with social shopping sites offering 50 percent discount, thus causing concerns about market distortion from a cutthroat competition. In order to overcome the limitations of social commerce remaining in the early stage, and to enhance the communication among consumers, this study conducted an empirical study on the social-commerce business models design based on context. The results of the study brought the imaginary, optimal combination model by conjoint analysis, using the segmented group through cluster analysis. To overcome the uniformity of social commerce and to enhance communication among consumers, the context-based optimal combination model should be proposed as the alternative social commerce business model in the domestic market which remains as a simple group-purchase function. Furthermore, this study will be used as an informative reference designing customer oriented service model for social commerce business.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.7
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• pp.602-617
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• 1990

In this paper, we analyze the performance of D-channel access protocol at the S-reference point for the ISDN user network interface recommended by CCITT. For the case of multipoint access to D-channel, a queueing model of D-channel access protocol is proposed. The delay is analyzed by decomposing it into waiting queue delay and contention delay. The contention delay is decomposed further into vain contention delay and pure contention delay so the analysis of the priority queueing system with symmetrical and asymmetrical arrival rates may be applied. The numerical results obtained are compared with the results of the single station queueing system served by the non-preemptive priority.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.314-321
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• 2011

There have been considerable standardization works to measure subjective video quality. However, these standardization methods are based on the situation where they have original or reference video sequences, and measure the video quality by looking the sequence during short time duration, e.g. 10 seconds. Since people's TV watching time durations in IPTV services are very long (e.g. more than 30 minutes), the quality measurements by the standards are not practical. In this paper, we analyze the effect of video quality rating period to MOS (Mean Opinion Score), and suggest a proper rating duration of subjective video quality for IPTV services.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.495-497
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• 2013

Wireless sensor networks (WSNs) have emerged as an attractive and key research area over the last decade. Time synchronization is a vital part of infrastructure for any distributed system. In embedded sensor networks, time synchronization is an essential service for correlating data among nodes and communication scheduling. This is realized by exchanging messages that are time stamped using the local clocks on the nodes. Various time synchronization protocols have been proposed aiming to attain high synchronization accuracy, high efficiency and low communication overhead. However, it requires that the time between resynchronization intervals to be as large as possible to obtain a system which is energy efficient having low communication overhead. This paper presents a simple but effective skew compensation algorithm that measures the skew rate of the sensor nodes with respect to the reference node and calibrates itself to compensate for the difference in the frequencies of the nodes. The proposed method can be incorporated with any existing time synchronization protocol for WSNs.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.1
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• pp.43-49
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• 2023

In modern wireless communication systems including beamformers or location-based services (LBS), which employ multiple antenna elements, estimating the number of signals is essential for accurately determining the quality of the communication service. Representative signal number estimation algorithms including the Akaike information criterion (AIC) and minimum description length (MDL) algorithms, which are information theoretical criterion models, determine the number of signals based on a reference value that minimizes each criterion. In general, increasing the number of elements mounted onto the array antenna enhances the performance of estimating the number of signals; however, it increases the computational complexity of the estimation algorithm. In addition, various configurations of array antennas for the increased number of antenna elements should be considered to efficiently utilize them in a limited location. In this paper, we introduce an efficient signal number estimation algorithm based on the beamspace based AIC and MDL techniques that reduce the computational complexity by reducing the dimension of a uniform circular array antenna. Since this algorithm is based on a uniform circular array antenna, it presents the advantages of a circular array antenna. The performance of the proposed signal number estimation algorithm is evaluated through computer simulation examples.

• The Journal of Society for e-Business Studies
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• v.24 no.2
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• pp.199-216
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• 2019

The public SW market is 3 trillion won, which is less than 10% of the total SW market. However, due to the nature of the domestic market, it is an important market with a relatively large impact on small and medium-sized software companies. In this market, government is operating the Public SW Project Demand Forecasting System in order to support the marketing activities of small and medium sized SW companies and establish a fair market order. The current system has limitations such as lack of user convenience, insufficient analysis capability and less business connection. This study was conducted to identify the problems of these systems and to propose a new system for improving the convenience of users and expanding the information utilization of SMEs. To this end, we analyzed the requirements of each stakeholder. We proposed the 2-phased forecasting cycle, the management cycle, and the system life cycle of public SW projects and created a unified identifier (UID) so that the information of those projects can be identified and linked among them. As a result, an integrated reference model of project information management based on system life cycle was developed, which can explain the demand forecasting and project information, and the improved processes was also designed to implement them. Through the result of this study, it is expected that integrated management of public SW projects will be possible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1982-1990
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• 1994

We implemented a PLDRO(Phase Locked Dielectric Resonator Oscillator) using the concept of the feedback property of PLL(Phase Locked Loop) for Ku-band(10.95-11.70 GHz). The conventional approaches to a PLDRO design use varactor diode tuning method.. But in theis paper, the PLDRO has the advantage of the frequency sensitivity to changes in the supple voltage of the oscillating device without the frequency-variable part by varactor diode voltage-control. and uses a SPD(Sampling Phase Detector) for phase-comparision. The PLDRO is composed of the DRO phase-locked to the reference signal of UHF band by using a SPD for high frequency stability and can be available for European FSS(Fixed Satellite Service) at 10.00GHz. The PLDRO generates the output power of 8.67 dBm at 10.00 GHz and has a phase noise of -81 dBc/Hz at 10 kHz offset from carrier. The hamonic and spurious characteristics have -42.33 dBc and -65dBc respectively. This PLDRO has much better frequency stability, lower phase noise, and more economical effect for a satellite system than conventional DRO.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1973-1981
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• 1994

A PLDRO(Phase Locked Dielectric Resonator Oscillator) in Ku-band(10.95-11.70GHz) is designed with the concept of the feedback property of PLL(Phase Locked Loop). A series feedback type DRO is developed, and VCDRO(Voltage Controlled Dielectric Resonator Oscillator) using a varactor diode as a voltage-variable capacitor is implemented to tune oscillating frequency electrically. Then, PLDRO is designed by using a SPD(Sampling Phase Detector). This PLDRO is phase-locked voltage controlled DRO to reference source(VHF band) by SPD at 10.00 GHz for European FSS(Fixed Satellite Service). The PLDRO generates output power greater than 10dBm at 10.00 GHz and has phase noise of -80 dBc/Hz at 10 KHz offset from carrier. This PLDRO achieves much better frequency stability than conventional VCDRO.