• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.58
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• pp.28-37
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• 2006

전파 자원은 국가의 무형 자산으로서 자원이 한정되어 있는 반면에 이에 대한 수요가 급증하면서 전파 자원의 가치가 점점 높아지고 있다. 특히 국내의 경우 IT839 전략으로 추진 중인 WiBro(Wireless Broadband), DMB(Digital Multimedia Broadcasting), Home Network, Telematics(Telecommunication Informatics), WCDMA(Wide Code Division Multiple Access), RFID/USN(Radio Frequency Identification/Ubiquitous Sensor Network) 등 무선 주파수를 이용하는 새로운 서비스가 증가하면서 주파수 자원에 대한 중요성은 더욱 강조되고 있다. 종래의 전파 정책이 정부가 정책을 세우고 이를 관리하는 Command-and-Control 위주였다면, 향후의 전파 정책은 OpYN1020en Spectrum 정책으로 전환될 것으로 전망된다. 본 고에서는 전파 자원의 효율적인 이용을 도모하는 일반적인 CR(Cognitive Radio) 기술에 대하여 언급하고, 이를 이동성이 없는 고정 환경에 적용하기 위한 IEEE 802.22 WRAN 시스템의 물리계층 전송 규격 사양, 프레임구조 및 현재 논의되고 있는 기술에 대하여 논의한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1058-1061
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• 2009

CDMA, WiBro, WLAN 네트워크를 포함하는 4세대(4G) 네트워크에서는 MN(Mobile Node)은 다양한 무선네트워크 인터페이스를 지원 해야만 한다. MN은 밧데리 전원에 의존하므로 에너지 효율은 네트워크 스캐닝의 관점에서는 매우 심각한 문제가 있다. 본 논문에서는 에너지효율을 위한 적응적인 네트워크 스캐닝 알고리즘을 제안 한다. 그 알고리즘은 네트워크 이동성과 사용자 트래픽등급을 고려한 두가지 방안으로 되어 있다. 네트워크 스캐닝 주기는 이동속도와 사용자 트래픽등급에 따라 적응적으로 변화 된다. 적응적인 네트워크 스캐닝 주기를 사용하여 MN은 불필요한 스캐닝을 최소화 하여 네트워크를 보다 에너지 효율적으로 스캐닝 할 수 있다. 제안한 네트워크 스캐닝 알고리즘을 위한 OPNET 시뮬레이션 결과들은 제안한 알고리즘이 고정된 스캐닝 주기를 가진 기존의 알고리즘보다 더 에너지 효율적이다는 것을 보여준다.

• ETRI Journal
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• v.34 no.3
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• pp.308-318
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• 2012

As mobile markets in most developed countries are rapidly coming close to saturation, it is increasingly challenging to cover the cost of providing the network, as revenues are not growing. This has driven mobile operators, thus far mostly involved in facility-based competition, to turn their attention to network sharing. There exist various types of mobile network sharing (MNS), from passive to active sharing. In this paper, we propose a model, based on the supply-demand model, for evaluating the economic effects of using six types of MNS. Our study measures the economic effects of employing these six types of MNS, using actual WiBro-related data. Considering lower service price and expenditure reduction, the total economic effect from a year's worth of MNS use is estimated to be between 513 million and 689 million USD, which is equal to three to four percent of the annual revenue of Korean mobile operators. The results of this study will be used to support the establishment of a MNS policy in Korea. In addition, the results can be used as a basic model for developing various network sharing models.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.13-18
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• 2016

In Internet of Things (IoT) environment, a variety of smart devices are connected to Internet through various network technologies such as 4G/5G, WiBro, Bluetooth, etc. in order to provide the remote monitoring service such as smart healthcare service, etc. Most standard mobility management protocols based on IETF Mobile IP may not be suitable for Internet of Things (IoT) environments due to constrained power, constrained CPU processing and memory capacity, and large signalling overhead which are inherently accompanied by various devices in IoT environments. In this article, we propose a new mobility management protocol CoMP (CoAP-based Mobility Managemenbt Protocol) for reliable mobility management in IoT environments. The architecture and algorithm to achieve both reliability and simplicity for IoT mobility management are proposed. Finally, performance has been evaluated by both mathematical analysis and simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.78-84
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• 2007

A multistandard direct-conversion mixer for WCDMA, Wibro, and 802.11a/b/g is designed in 0.18 um CMOS technology To support multistandard and to reduce the chip area the switched inductor is used as the matching method. This switched inductor matching network selects the mixer's operation frequency band by turning on or off the switch transistor. Since the performances of mixer and operation frequency can be affected by the parasitic of switch transistor the mixer should be designed with the optimized size of switch to minimize parasitic effects. Proposed mixer is able to achieve return loss less than -13 dB in $2.1\sim2.5GHz$ and $5.1\sim5.9GHz$ bands with the suitable performance to meet requirements of WCDMA, WiBro, and 802.11a/b/g.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.917-926
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• 2019

At present, TICN has been developed and distributed for military command control. TICN is known as the 3.5G mobile communication technology based on WiBro, which shows technical limitation in the field operation situation. Accordingly, the drone-type base station platform is attracting attention as an alternative to overcome technical limitations such as difficulty in securing communication LoS and limiting expeditious network configuration. In this study, we performed simulation performance evaluation of drone-type base station operation in 28 GHz that is considered most suitable for cellular communication within mmWave frequency band. Specifically, we analyzed the changes in throughput and fairness performance according to radio resource management policies such as frequency reuse and scheduling in multi-cell topology. Through this, we tried to provide insights on the operation philosophy on drone-type base station.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.602-607
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• 2007

최근 4G 이동통신 시스템의 진화를 위한 단계로 기존의 이동통신 시스템을 유지하면서 효율 극대화를 통한 비용 절약 측면과 고 주파수 대역을 이용한 셀 간격의 협소화로 인해 나타나는 문제점에 대한 대안으로 커버리지 확대와 데이터 처리율 향상을 위한 IEEE 802.16j 표준화 작업이 진행 중에 있다. 향후 VoIP 서비스를 위한 업링크 스케줄링 기법으로 몇 가지가 IEEE 802.16j에 제시되어 있으나, 본 논문에서는 보이스 트래픽 특성 및 수학적 모델링을 통하여 기존 방법들보다 더 효율적인 대역 이용을 통해 같은 대역폭 대비 성능과 용량 면에서 개선된 스케줄링 기법인 eertPS를 제시하여 IEEE 802.16j Multi-Hop 환경하에서도 대역 효율적인 VoIP 서비스를 이용할 수 있도록 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.327-332
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• 2007

휴대인터넷 기반에서의 응용 서비스로서 메시지를 교환할 수 있는 메신저 서비스와 버디들과의 음성통화 그리고, 스토리지 연결을 통한 실시간 스토리지 서비스 마지막으로 컨텐츠 목록 중에서 원하는 동영상을 선택하여 플레이 할 수 있는 실시간 스트리밍 서비스를 할 수 있도록 각 서비스들의 구조 및 기능에 대하여 구현하였다. 본 응용 서비스를 활용하여 휴대인터넷 환경에서 사용자간의 편리한 커뮤니케이션이 기대된다.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.89-94
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• 2011

Telemedicine system means a remote support system among 4 remote telemedicine services of u-Health. A currently available service in Korea is the one checking and maintaining patient's status and supporting in emergency through video communication between an ambulance transferring patients and hospital under HSDPA and WiBro environment with coding of MPEG-2 and MPEG-4. With that, this paper improves the stability of the current telemedicine system service of ambulance confirms the improvement compared to the old system by generating a system communicating by RTP/RTCP under coding process through H.264/AVC after converting RGB video to YUV in order to improve network efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.184-184
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• 2008

In this paper, a power divider with a multi-band and broadband are designed and fabricated using an InGaP/GaAs process. The design of this divider is based on multi-band because it is important in the next generation IMT-Advances system. In this design, power divider is fabricated with the frequency of 824 MHz to 894 MHz, 1.8 GHz to 2.2 GHz and 2.3 GHz to 2.4 GH for cellular, personal communication system (PCS) and Wireless Broadband Internet (WiBro). The topology of the designed power divider is based on the multi-section and fabricated using integrated passive device (IPD) library of nanoENS Inc. It is measured using network analyzer.