• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.687-689
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• 2004

As using of network increases rapidly, performance of system has been deteriorating because of the overhead and bottleneck. Nowadays, High speed I/O network standard, that is a sort of PCI Express, HyperTransport, InfiniBand, and so on, has come out to improve the limites of traditional I/O bus. The InfiniBand Architecture(IBA) provides some protocols to service the applications such as SDP, SRP and IPoIB. In our paper, We explain the architecture of IPoIB (IP over InfiniBand) and its features in channel based I/O network. And so we provide a performance evaluation result of IPoIB which is compared with current network protocol. Our experimental results also show that IPoIB is batter than TCP/IP protocol. For this test, We use the dual processor server systems and Linux Redhat 9.0 operating system.

• 대한전자공학회논문지SD
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• 제43권11호
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• pp.77-82
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• 2006

직접 변환 방식의 IEEE 802.11a 무선랜 수신기에 사용되는 아날로그 채널 선택 필터에 대하여 기술한다. 채널 선택필터는 10MHz의 차단주파수를 갖는 5차의 체비셰프 필터이며 active-RC 구조로 설계되었다. 2단의 연산증폭기를 사용하였는데, 전력 소모를 최소화하기 위하여 전류재사용 feedforward 주파수 보상 방법을 사용하였다. 필터는 $0.l8{\mu}m$ CMOS 공정을 사용하여 제작하였으며 1.8V의 전원 전압에서 20mW의 전력 소모를 갖고 있으며 19dBV의 out-of-band iIP3를 갖는다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.109-112
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• 2001

Recently, as demands for super-high speed broad band wireless multimedia service increase, variable researches to develop wireless LAN have been carried out. In this paper, we propose and analyze LS(Least Squares)-PSA(Pilot Symbol Assisted) equalizer which compensates for each subcarrier of different attenuations and phase response for OFDM(Orthogonal Frequency Division Multiplexing)-based indoor wireless LAN systems. The proposed equalizer enhances the $E_{b}$ $N_{o}$ performance of 3dB and 4dB at BER=10$^{-2}$ as compared with LS equalizer in AWGN channel and indoor wireless channel respectively..

• 정보통신설비학회논문지
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• 제3권2호
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• pp.18-25
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• 2004

As using of network Increases rapidly, performance of system has been deteriorating because of the overhead and bottleneck. Nowadays, high speed I/O network standard, that is a sort of InfiniBand, PCI Express and so on, has come out to improve the limites of traditional I/O bus. The InfiniBand provides some protocols to service the applications such as SDP, SRP and IPoIB. In our paper, We explain the architecture of SDP(Socket Direct Protocol) and its features in channel based I/O network. And so, we provide a result of performance evaluation of SDP which is compared with current network protocol. Our experimental results also show that SDP is better than TCP/IP protocol.

• 대한전자공학회논문지SD
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• 제41권8호
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• pp.51-57
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• 2004

Cascaded FBG(fiber Bragg grating)의 1차 분산과 2차 분산을 해석한 뒤 cascaded FBG의 2차 분산이 WDM/SCM (wavelength division multiplexing/subcarrier multiplexing) 시스템에서 발생한 왜곡 성분에 미치는 영향에 대하여 분석하였다. 아날로그 CATV의 최대 허용 왜곡 레벨인 IM₂ < -60 dBc, IM₃ <-95 dBc를 적용하여 최대 허용 왜곡 레벨에 도달하게 되는 값을 구하였고, 이 값을 통하여 왜곡의 허용 레벨 아래를 유지하기 위한 조건들을 제시하였다. Cascaded FBG-OADM을 사용한 WDM/SCM 시스템에서 공통주파수가 600 MHz, 광파장의 채널 간격이 50 GHz인 경우 FBG.의 3dB 반사 대역폭은 채널간격의 18 % 미만이 되어야 하며, 동일 조건에서 직접 변조 방식인 경우 18 %, 외부 변조 방식인 경우 70 % 미만이 되어야 한다는 제한을 받았다. 채널 간격이 50 GHz인 경우 공통주파수는 310 MHz 미만이 되어야 하며, FBG의 길이가 8 m인 경우 2차 혼변조 왜곡이 20 dB 이상 증가하였다.

• 한국통신학회논문지
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• 제25권10B호
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• pp.1675-1689
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• 2000

We present CReMeS a CORBA-compliant design and implementation of a new real-time communication service. It provides for efficient predictable and scalable communication between information producers and consumers. The CReMeS architecture is based on MidART's Real-Time Channel-based Reflective Memory (RT-CRM) abstraction. This architecture supports the separation of QoS specification between producer and consumer of data and employs a user-level scheduling scheme for communicating real-time tasks. These help us achieve end-to-end predictability and allows our service to scale. The CReMeS architecture provides a CORBA interface to applications and demands no changes to the ORB layer and the language mapping layer. Thus it can run on non real-time Off-The-Shelf ORBs enables applications on these ORBs to have scalable and end-to-end predictable asynchronous communication facility. In addition an application designer can select whether to use an out-of-band channel or the ORB GIOP/IIOP for data communication. This permits a trade-off between performance predictability and reliability. Experimental results demonstrate that our architecture can achieve better performance and predictability than a real-time implementation of the CORBA Even Service when the out-of-band channel is employed for data communication it delivers better predictability with comparable performance when the ORB GIOP/IIOP is used.

• 전기전자학회논문지
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• 제20권1호
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• pp.54-60
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• 2016

본 연구에서는 우리나라 DTV 방송의 대역외발사강도 기술기준 및 기존 측정방식의 문제점들을 분석하였으며, 지상파 DTV 방송의 대역외발사강도를 효과적으로 측정할 수 있는 방안들을 제안하였다. 고가의 전용 측정장비로만 측정가능한 기존방식에 비해 제안한 방식은 범용장비로도 대역외발사강도를 손쉽게 측정할 수 있으며, 실제 측정시스템 구현을 통하여 제안한 방식의 유효성을 입증하였다. 본 논문에서 제안된 방식은 경제적이고도 간편하므로 방송장비 이외의 무선 송신장치 특성측정에도 널리 사용될 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권8호
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• pp.1894-1912
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• 2012

This paper proposes a system called Wireless Link based on Global Communication Channel (WLGCC) to enhance the spectrum sharing between digital broadcasting (DB) services and the cognitive radio (CR) system in the licensed band of 470-790 MHz. The WLGCC aims to enhance the spectrum sensing and geolocation database (GLD) spectrum sharing methods in the CR system. Spectrum sensing can be enhanced by receiving the status of the used frequencies from the WLGCC, thereby eliminating the need for a low detection threshold (i.e., avoiding the hidden node problem). In addition, the GLD can be enhanced by providing a reliable communication link between the database and the CR device in the form of an unused TV white space that is reserved as the proposed Global Communication Channel (GCC). This paper analyzes the coexistence of the new WLGCC system and the DB service in terms of avoiding additional interference. Specifically, we mathematically determine the WLGCC parameters, such as the in-band and out-of-band power levels, and operation coverage, and verify them using Monte Carlo simulation. The results show that WLGCC does not degrade the existing DB service and reliably transmits information of the vacant (or used) frequency bands to the CR.

• 인터넷정보학회논문지
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• 제16권6호
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• pp.1-9
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• 2015

본 논문에서는 이기종 네트워크를 구성하는 대표 무선접속 기술인 WiMAX, CDMA, 무선랜 간의 주파수 공유 분석을 수행하였다. 3가지 접속기술은 각기 다른 주파수 대역을 사용하지만 대역외 방사특성으로 인해 타 무선접속 기술에 간섭을 일으킬 수 있다. 따라서 간섭 허용기준을 만족하기 위한 최소 인접채널 간섭률을 산출하고 이를 바탕으로 간섭/피간섭 시스템간의 최소 주파수 이격(보호대역)을 산출하였다. 분석 결과 WiMAX와 무선랜 간에는 적어도 20 MHz의 보호대역, WiMAX와 CDMA시스템 간에는 적어도 15 MHz의 보호대역이 필요함을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.290-292
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• 2009

With advance in technologies for wireless sensor networks(WSNs), 2.4 GHz band has become gradually attractive due to increase in low-power wireless communication devices. Especially ZigBee(IEEE 802.15.4-based) technology whose frequency band includes the 2.4GHz industrial, scientific and medical band providing nearly worldwide availability has been universally applicable to a various remote monitoring system and applications related home network system. However network throughput of these systems is significantly deteriorated due to this ISM band is a license-exemption used in a variety of low-power wireless communication devices. For instance, other IEEE 802 wireless standards such as Bluetooth, WLAN, Wi-Fi and others cause radio interference to ZigBee. The experiments was carried out to analyze radio frequency interference between heterogeneous devices using ISM bands to improve the limited frequency utility factor. Finally this paper suggests a frequency hopping-based adaptive multi-channel methods to decrease interference with empirical results.