• Journal of KIISE:Information Networking
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• v.37 no.6
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• pp.494-498
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• 2010

Performance requirements of a system are usually closely related to the quality of service provided by the system. The call success rate of a mobile communication system is, for example, directly linked with the quality of call service. Therefore, meeting the performance requirements is one of the critical issues during the operation of services as well as in system development. In this paper, we present a testing method for evaluating the call success rate of a mobile communication system by using interval estimation. Also we analyze the criterion used in the evaluation of the quality of 3G mobile communication services which was recently performed by Korea Communications Commission and then discuss the problems.

• Journal of the Korean Data and Information Science Society
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• v.18 no.1
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• pp.81-96
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• 2007

The headline of advertisements holds the important position in advertisement recognition and receptivity. In this paper, we classified the headlines as several types with measuring the response effects for purpose of understanding the customer's behavior. Also we conducted the decision tree analysis and correspondence analysis. The decision tree shows the difference between responders and non-responders, and the correspondence analysis shows the relationship between the sales and the customer's demographic information.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.225-228
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• 2004

본 논문은 이동통신을 위한 입력영상을 취득할 때 사용되는 웨이블릿, 소벨 필터 기반의 화질평가 방식을 다양한 실험을 통해 검증하고 영상과 전처리 기법에 따라 주관적 평가에 근접한 화질평가방식을 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.493-499
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• 2015

In Korea mobile phone subscribers exceeded 1 million people in 1995, and ten million people in 1998. Prevalence of the mobile phone increased dramatically over 110% compared to the population. Almost every family members including children uses more than one mobile terminal. Mobile phone is obviously more necessary good than washer, vacuum cleaner and passenger car. Our daily life are conveniently positioned with mobile communication, but communication related costs including the price of the device and service charges become a big burden on the household. But the government does not seem to do the right role at the right time to prevent the market failure to maximize consumer welfare and social welfare through supporting fair competition. This principal-agent problem issues of mobile communication policies will be understood in perspective of public choice against joint use of the mobile communication network, number portability, separation of phone distribution and phone service, network neutrality, mobile phone subsidy since the early 1990s when mobile phone service was introduced in Korea.

• Journal of Korea Technology Innovation Society
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• v.20 no.4
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• pp.1243-1261
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• 2017

Mobile telecom markets have dramatically increased in the last decade due to a remarkable subscriber base growth. The diffusion patterns of the services are a major concern for mobile carriers preparing those new services. We assume that the diffusion patterns of those services will be similar to those of previous mobile services, and discovering the diffusion patterns of those services is an essential task of mobile carriers for preparing the next mobile services. This study attempts to classify some groups which show similar diffusion patterns of mobile services. Using a traditional diffusion model, this study estimates diffusion patterns of twenty five western European countries. The estimation is based on the monthly penetration ratio of those countries from 1993 to 2004. Based on the estimation, the cluster analysis discovers that there are two different countries groups in terms of mobile diffusion pattern: high imitation countries and low imitation countries. The critical point for classifying the two groups in terms of imitation effect was 0.90. The results provide the basis for developing a causal relationship model which explains the different diffusion pattern of mobile services and planning new networks for the advanced mobile services.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1018-1025
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• 2011

Scalable Video Coding (SVC) extension of H.264/AVC is a new video coding standard for media convergence by providing diverse videos of different spatial-temporal-quality layers with a single bitstream. Recently, real-time SVC codecs are being developed for the application areas of surveillance video and mobile video, etc. This paper presents the design and implementation of a H.264/SVC decoder based on an embedded DSP using Open SVC Decoder (OSD) which is a real-time software decoder designed for the PC environment. The implementation consists of porting C code of the OSD software from PC to DSP environment, profiling the complexity performance of OSD with further optimization, and integrating the optimized decoder into the TI Davinci EVM (Evaluation Module). 50 QCIF/CIF frames or 15 SD frames per second can be decoded with the implemented DSP-based SVC decoder.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.24-30
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• 2007

The integration of WLAN and beyond 3G mobile networks offers the possibility of achieving anytime and anywhere Internet access. Moreover the requests for seamless multimedia services and the Quality of Service (QoS) support have been one of key issues in wireless networks. Therefore the researches relative to seamless multimedia service and QoS over heterogeneous wireless networks have been progressing rapidly. In this paper, we propose inter-working architecture for supporting seamless multimedia service and QoS over WLAN and WiBro networks. Based on the proposed inter-working architecture, we also provide both the seamless handover architecture such an inter-network vertical handover and the QoS-aware wireless Medium Access Control (MAC) scheme. In addition, we evaluate and compare the performance by Network Simulator-2 (NS-2) simulations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.693-696
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• 2008

The systems for mobile communication services of fourth generation use OFDM (Orthogonal Frequency Division Multiplexing) scheme that ran transmit large amounts of data to support the multimedia services, and consist of several types of cell, such as Macro Cell, Pico Cell, Femto Cell to improve the qualify of service. According to subdivision of communication region, superposition of cells in co-channel different from conventional single cell is used, but it cause inter band interference between systems. In particular, an OFDM signal consists of a number of independently modulated subcarriers, and superposition of these subcarriers causes a problem that ran give a large PAPR. Increased PAPR induces signal distortion passing through components such as power amplifier so that inter band interference is caused by out-of-band spectrum radiation. In order to minimize the inter band interference, this paper applies PAPR reduction scheme and analyzes the out-of-band spectrum radiation when the signal passes through nonlinear components such an power amplifier.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.589-592
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• 2007

Ubiquitous environment means the environment in which users can access the Internet at anytime and anywhere. Network mobility support is needed for seamless Internet service in ubiquitous environment. When users try to access the Internet in public transportation such as bus, train, airplane, to support network mobility by composing several sub-networks is more efficient than to support host mobility. IETF established 'Network Mobility(NEMO)' working group to research and develop network mobility technology. In this paper, we investigate the concept of network mobility, trends of research in NEMO and developed technology on the basis of 'Network Mobility Basic Support Protocol' standardized by IETF.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.113-116
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• 2005

In general, multiple mobile hosts (MH) access at a base station (BS) that terminates the wired link and relays data flow to the wireless link in wired and wireless heterogeneous network. In this network, the BS is tend to be a bottleneck and to degrade a network performance. Many studies have been done throughout several protocol layers. Especially on the transport layer, many techniques were studied to enhance TCP performance. But most of them are concerned to enhance TCP throughput and TCP fairness is hardly considered. In this paper, an algorithm for enhancing TCP fairness is proposed and its performance is verified by ns-2 simulation.