• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.265-267
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• 2005

본 논문에서는 무선 랜과의 인터워킹 등 새로운 특징을 갖는 주요 기능들을 추가하기 위한 기반 시스템인 3G Evolution 시스템 개발에 필요한 액세스 시스템 내의 서브 시스템인 RRCS(Radio Resource Control Subsystem)를 구현 및 검증하기 위하여 단말-기지국간 무선 액세스 프로토콜을 형식 기술 언어인 SDL(Specification and Description Language)을 이용해 구현하였다. 여기서 효율적 시스템 설계를 위해 복잡한 각 메시지 처리 함수는 C 언어를 이용해 라이브러리화하고 이를 SDL 시스템 내에서 호출하도록 지원하는 방법을 사용했다.

• TTA Journal
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• s.100
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• pp.51-57
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• 2005

차세대 이동통신 표준화는 크게 네가지 분야에서 진행되고 있다. 3GPP, 3GPP2에서의 3G Evolution, IEEE 802.16에서의 Broadband Wireless Access, OMA에서의 응용서비스의 표준화, 그리고 ITU-R에서의 Spectrum 및 Beyond 3G 비전 연구 등이다. 본 고에서는 현 시점에서 각 기구에서 진행되고 있는 표준활동의 개요를 간단히 소개한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.712-723
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• 2013

Recent exploration of smart-phone user is fueling the deployment of long term evolution (LTE) service that offers higher data rates service over 3G HSPA networks. In particular, Korea, mobile powerhouse, recently launched the service of LTE-Advanced (LTE-A) which is the latest release in LTE standard. Multiple-input-multiple-output (MIMO) technology is the one of key enablers for LTE and LTE-A for achieving high data rate. MIMO technology has received much attention since it is possible to achieve channel capacity in proportion to the number of antennas without increasing frequency and power. In this paper, we overview of the theoretical background of MIMO technology regarding from single-user MIMO, multiuser MIMO, and massive MIMO and design considerations to implement the communication system.

• Asian Journal of Innovation and Policy
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• v.2 no.2
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• pp.150-172
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• 2013

This paper wanted to find out research trends and its determinants on mobile commerce research reviewing 439 articles from 1999, the starting year of this field to 2012. Our analytical framework has 4 categories such as general, technology, consumer and firm, and 14 sub-categories. The results are as follows: First, studies on mobile commerce can be divided into 5 stages. Second, trends of mobile commerce are closely related to the evolution of mobile technologies such as communication technologies and devices (2G, 3G, 3G+, 4G LTE, LTE-A). Third, this field was led by USA until 2005 and has been led by Taiwan after 2006. Fourth, China, Korea, UK and Canada are also leading countries, all of which have mobile device manufacturers. Research trends of non-manufacturing countries and manufacturing countries are different from each other. In addition, the trends of leading countries are different from each other reflecting each country's business needs.

• Ocean Systems Engineering
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• v.2 no.3
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• pp.189-203
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• 2012

New experiments focusing on the evolution characteristics of nonlinear wave trains were conducted in a large wave flume. A series of wave trains with added sidebands, varying initial steepness, perturbed amplitudes and frequencies, were physically generated in a long wave flume. The experimental results show that the increasing wave steepness, increases the speed of sidebands growth. To study the frequency and phase modulation, the Morlet wavelet transform is adopted to extract the instantaneous frequency of wave trains and the phase functions of each wave component. From the instantaneous frequency, there are local frequency downshifts, even an effective frequency downshift was not observed. The frequency modulation increases with an increase in amplitude modulation, and abrupt changes of instantaneous frequencies occur at the peak modulation. The wrapped phase functions show that in the early stage of the modulation, the phase of the upper sideband first diverges from that of the carrier waves. However, at the later stage, the discrepancy phase from the carrier wave transformed to the lower sideband. The phase deviations appear in the front of the envelope's peaks. Furthermore, the evolution of the instantaneous frequency exhibits an approximate recurrence-type for the experiment with large imposed sidebands, even when the corresponding recurrence is not observed in the Fourier spectrum.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.1-9
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• 2004

User-Perceived application-level performance is a key to the adoption and success of CDMA 2000. To predict this performance in advance, a detailed end-to-end simulation model of a CDMA network was built to include application traffic characteristics, network architecture, network element details, and protocol features. We assess the user application performance when a Radio Access Network (RAN) and a Core Network (CN) adopt different transport architectures such as ATM and If. For voice Performance, we found that the vocoder bypass scenario shows 8% performance improvement over the others. For data packet performance, we found that HTTP v.1.1 shows better performance than that of HTTP v.1.0 due to the pipelining and TCP persistent connection. We also found that If transport technology is better solution for higher FER environment since the IP packet overhead is smaller than that of ATM for web browsing data traffic, while it shows opposite effect to small size voice packet in RAN architecture. Though simulation results we showed that the 3G-lX EV system gives much better packet delay performance than 3G-lX RTT, the main conclusion is that end-to-end application-level performance is affected by various elements and layers of the network and thus it must be considered in all phases of the technology evolution process.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.8-15
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• 2022

The new 5G radio technology (NR) can provide ultra-reliable low latency communications. The supporting 5G network infrastructure will move away from the previous point-to-point network architecture to a service-based architecture. 5G can provide three new things, i.e., wider channels, lower latency and more bandwidth. These will allow 5G to support three main types of connected services, including enhanced mobile broadband, mission-critical communications, and the massive Internet of Things (IoT). In 2015, the 5th generation (5G) mobile communication was officially approved by the International Telecommunication Union (ITU) as IMT-2020. Since then, 3GPP, the international organization responsible for 5G standards, is actively developing specifications for 5G technologies. 3GPP Release 15 provides the first full set of 5G standards, and the evolution and expansion of 5G are now being standardized in Release 16 and 17, respectively. This paper provides an overview of 3GPP 5G technologies and key services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10C
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• pp.764-777
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• 2008

In 4G environments, which is the next generation technology for mobile network, it is forecasted that the wireless Internet using a mobile devices such as a mobile phone, PDA will increase because of expansion of Internet and integration of heterogeneous networks. Therefore, we need a Digital ID management technology that can prevent illegal uses and manage private information efficiently in wired and wireless environments. In this paper, we analyze various Digital ID management technologies, and then define requirements of user-centric Digital ID management technology. In addition, we newly propose the authentication mechanism for mobile applications in LTE/SAE network. Finally, we propose the mobile Digital ID Wallet mechanism suitable for 4G environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.565-572
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• 2007

3G Long Term Evolution (3G LTE) is a next generation cellular networks system capable or providing various mobile multimedia services by using OFDMA and MIMO based radio access technology. Among many differences from existing WCDMA based systems, the facts that 3G LTE uses Physical Resource Block (PRB) as its radio resources and provides all services through the PS domain make the development of new resource management schemes necessary. This paper proposes an adaptive partitioning based downlink call admission control scheme. It separates realtime call requests from non-realtime ones, specifies maximum allowable resource amounts for each type, but if the maximum is exceeded, call requests are accepted with probability proportional to remaining resource amounts. Despite the fact that such adaptive concept has been already adopted by other call admission schemes, the contributions of our paper, which are that we are able to find an efficient way to apply the proposed scheme exploiting PRB characteristics and measure the resource usage of base stations by PRB utilization and payload ratio, are still valid. When judging from simulation results in comparison with others, our scheme is able to prioritize realtime call requests over non-realtime ones, and at the same time, overall system performance is superior.

• Information Systems Review
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• v.13 no.2
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• pp.43-54
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• 2011

The paper presents the technology trajectory of competitive wireless technologies in wireless industry. We attempt to trace the trajectory of wireless technologies with historical data, and then analyze its pattern. As a preliminary result, we find that there exists network effect and substitution effect in the trajectory. Our result can provide insight to wireless service providers where best to focus its efforts for maximizing overall gain in their networks as well as when to establish the transition strategy towards the next generation wireless network technologies.