• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.441-446
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• 2003

Earlier efforts on optical access concentrated on the design of PONs for the collection and distribution portion of the access network. The PON architecture is very simple but it requires a MAC protocol for control of upstream traffic. The MAC protocol must support QoS (Quality of Service) administration function by various traffic class, efficient dynamic bandwidth assignment function, CDV (Ceil Delay Variation) minimization function etc. This paper proposes a dynamic bandwidth assignment algorithm of the MAC protocol for a broadband access network using an Ethernet Passive Optical Network supporting various traffic class. We compare our proposed with MDRR algorithm using simulation, and confirmed that our proposed Request-Counter algorithm produces shorter average cell delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11C
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• pp.1095-1101
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• 2007

For the cognitive radio (CR) systems sharing the spectrum with narrowband primary devices, this paper presents a fractional bandwidth (FBW) mode utilizing a variable portion of the system band to avoid the interference to or from the primary devices. For the method, the preamble and FBW mode detection algorithm are provided to obtain the FBW mode information during the synchronization. Simulation results in wireless regional area network (WRAN) environments reveal that the FBW mode can be detected reliably without any deterioration of the synchronization performance.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.193-199
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• 2017

In the paper, a dual band-notched monopole antenna is proposed for 2.4 GHz WLAN (2.4 ~ 2.484 GHz) and UWB (3.1 ~ 10.6 GHz) applications. The 3.5 GHz WiMAX band notched characteristic is achived by a pair of L-shaped slots instead of the previous U-shaped slot on the center of the radiating patch, whereas the 7.5 GHz band notched characteristic is achived by C-shaped strip resonator placed near to the microstrip feed line. The measured impedance bandwidth (${\mid}S_{11}{\mid}{\leq}-10dB$) is 8.62 GHz (2.38 ~ 11 GHz) which is sufficient to cover 2.4 GHz WLAN and UWB band, while measured band-notched bandwidths for 3.5 GHz WiMAX and 7.5 GHz bnad are 1.13 GHz (3.15 ~ 4.28 GHz) and 800 MHz (7.2 ~ 8 GHz) respectively. In particular, it has been observed that antenna has a good omnidirectional radiation patterns and higher gain of 2.51 ~ 6.81 dBi over the entire frequency band of interest.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2770-2776
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• 2011

Mutual Interference scenarios between Wireless Broadband (WiBro) and Wireless LAN (WLAN) in DTV bands are assumed. Co-channel interference and adjacent channel interference are respectively evaluated in terms of carrier to interference ratio (C/I) by using Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) based on the Monte-Carlo simulation method. For the simulation, three frequencies such as 185 MHz, 481 MHz and 687 MHz are chosen. Analysis results indicate that interference situation of using frequency of 185 MHz is the worst case, which requires longer protection distance between WiBro MS and WLAN User Equipment (UE), lower transmit power of WiBro Mobile Station (MS) and WiBro Base Station (BS) and WLAN UE and larger guard band. Comparing to cases of using frequency of 185 MHz and 481 MHz, interference situation of using frequency of 687 MHz is slighter. Therefore, using frequency of 687 MHz is easier for coexistence between WiBro and WLAN. Analysis results can be used as reference and guideline when planning the deployment of WiBro and WLAN in DTV bands.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.388-396
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• 2019

This paper describes the RF(Radio Frequency) interference on the GNSS receiver due to the S-band signals transmitted from the transmitters in the Test Launch Vehicle, and analyzes the cause of the RF interference. Due to the S-band signals that have relatively high power levels compared with GNSS signals, an LNA(Low Noise Amplifier) in the active GNSS antenna was saturated, and the intermodulation signal within GNSS in-bands was produced in the LNA whenever two S-band signals were received from the GNSS antenna. For these reasons, the C/N0 of the satellite signals in the GNSS receiver was attenuated severely. The design of the LNA was changed in order to protect the RF interference due to the S-band signals and the suppression capability of the RF interference was confirmed in the new LNA through the comparison of the old LNA.

• Photonics industry news
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• s.35
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• pp.24-29
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• 2006

럭스퍼트(대표 변재오)는 광증폭기(EDFA, Raman), BLS, RFTS, 광철체시스템 등 광통신 관련 제품 전문 기업이다. 대용량화 및 고속화로의 진화과정을 입증하듯 광통신의 WDM의 채널 간격은 점차로 좁아지고 있으며, 광섬유 생산 기술의 놀라운 발전으로 기존의 C-bard 대역 이외에도 L-band, S, S+ 등의 새로운 파장 대역이 계속해서 통신 대역으로 진입하고 있다. 이러한 세계적 추세와 더불어 (주)럭스퍼트는 기존에 EDFA 관련 축적된 기술을 더욱 견고히 할뿐만 아니라, Raman 증폭기 및 S-band, S+band의 시장에 기여하기 위해 새로운 기술력을 축적해 왔다.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3127-3129
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• 2000

본 논문에서는 광 다이오드에서 들어오는 신호로부터 원하는 대역의 신호를 얻기 위한 적외선 수신 IC에 적합한 대역통과필터를 설계하였다 설계한 대역통과필터는 2차 Biquad gm-C 필터의 구조를 이용하여 중심주파수가 38kHz. Quality factor가 10인 필터를 구현하였다. 구현된 대역통과필터는 필터부분과 중심주파수를 보정해 주는 frequency tuning 부분으로 구성되어 있다. 낮은 transconductance와 높은 선형성을 요구하는 transconductor의 설계를 위해 Gilbert 곱셈기 특성을 이용하여 구현하였고 AMS사의 0.8${\mu}m$ BiCMOS model을 사용하여 +5V로 동작되도록 설계 하였다

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.9-17
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• 2007

This paper shows an implementation of the baseband processor compliant with the IEEE 802.11a standard. Some innovative techniques are proposed to fulfill the mandatory requirements of the standard. For verification and analysis of this design, we use a Platform-based SoC (system on chip) environment. The entire system consists of test-board for the baseband processor chip and the SoC platform for implementing MAC (medium access control).

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.78-85
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• 1998

The design method of a temperature stable bandpass filter using dielectric coaxial resonators of with two dielectric ceramics with opposite signs of temperature coefficient of dielectric constant (${\tau}_{\epsilon}$) to compensate for each other in this method. $MgTiO_3$(${\tau}_{\epsilon}$=+99 ppm/${\circ}C$) as a positive ${\tau}_{\epsilon}$ material and Ba($Zn_{1/3}Nb_{2/3}$)$O_3$(${\tau}_{\epsilon}$=-77ppm/${\circ}C$) as a negative material were selected. The length of a SIR for the temperature stability was calculated according to the design method and the susceptance slope parameter of the SIR was obtained. A temperature stable bandpass filter using dielectric SIR's was designed, simulated and fabricated. The center frequency of this filter was 915 MHz and the pass bandwidth was 20 MHz. Temperature properties of this bandpass filter by simulations were compared with the measured results of the bandpass filter fabricated.

• The Optical Journal
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• s.141
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• pp.26-26
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• 2012

(주)이오시스템이 지난 8월 23일 역삼동 르네상스 호텔에서 열린 '2012년 제2회 신기술인 증서 수여식'에서 'UV-C 대역 검출을 위한 필터용 필름 제조기술'로 신기술인증(NET)을 획득했다. 지식경제부 기술표준원과 한국산업기술진흥협회가 공동 주관하는 신기술인증은 국내 기업, 연구기관, 대학 등에서 개발한 신기술을 조기에 발굴하고 우수성을 인증함으로써 개발된 신기술의 상용화와 기술거래를 촉진하는 것을 목적으로 한다.