• 제목/요약/키워드: Broadband Characteristics

검색결과 433건 처리시간 0.026초

광대역 수중 스피커 시스템의 설계 및 성능 특성 (Design and Performance Characteristics of a Broadband Underwater Speaker System)

  • 이대재
    • 한국수산과학회지
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    • 제44권5호
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    • pp.543-549
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    • 2011
  • An underwater speaker was developed for use as an acoustic deterrent device that transmits acoustic energy through the water omnidirectionally over a broadband frequency range to eliminate marine mammal attacks and to prevent physical damage to the inshore and coastal fishing grounds of Korea. The underwater speaker was constructed of two vibration caps machined from 6061-T6 aluminum alloy and a stack of PZ 26 piezoelectric ceramic rings (Ferroperm Piezoceramics A/S) connected mechanically in series and electrically in parallel. The performance characteristics of the underwater speaker were measured and analyzed in an experimental water tank of $5\;m{\times}5\;m{\times}6\;m$. The peak transmitting voltage response (TVR) was measured at 11.16 kHz with 163.45 dB re $1\;{\mu}Pa$/V at 1m. The underwater speaker showed a near omnidirectional beam pattern at the peak TVR resonance frequency. The usable frequency range was 4-25 kHz with a lower TVR limit of approximately 140 dB. We conclude that this underwater speaker could be satisfactorily used as an acoustic deterrent device against marine mammals, particularly the bottlenose dolphin, to protect catches and fishing grounds as well as the mammals themselves, for example, by keeping them away from fishing gear and/or vessels.

살오징어(Todarodes pacificus)와 갑오징어(Sepia esculenta)에 대한 광대역 음향산란특성의 비교 (Comparison of Broadband Acoustic Scattering Characteristics Between Japanese Flying Squid Todarodes pacificus and Golden Cuttlefish Sepia esculenta)

  • 이대재
    • 한국수산과학회지
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    • 제52권6호
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    • pp.709-718
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    • 2019
  • Cephalopods, such as the Japanese flying squid Todarodes pacificus and golden cuttlefish Sepia esculenta, are an important food source for all toothed whales, particularly bottlenose dolphins in costal and offshore waters around the Korean Peninsula. A controlled laboratory experiment was conducted to investigate the broadband acoustic backscattering from live individuals of these two cephalopod species using linear chirp signals (100-200 kHz). The backscattered echo signal was measured at about 1° intervals from -45° (head down) to +45° (head up) in the dorsal plane. The species-specific, frequency-dependent scattering characteristics were investigated by comparing the relationship between the wavelength-normalized backscattering cross-section (σ/λ2) and the wavelength-normalized fish length L/λ for each species. The estimated σ/λ2 value for Japanese flying squid was 9.51 at an L/λ range of 12.79-30.27 (mean, 21.26). This was approximately 7% of the σ/λ2 value (136.1) for golden cuttlefish at an L/λ range of 9.07-25.49 (mean, 15.77).

An Ultra Wideband Low Noise Amplifier in 0.18 μm RF CMOS Technology

  • Jung Ji-Hak;Yun Tae-Yeoul;Choi Jae-Hoon
    • Journal of electromagnetic engineering and science
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    • 제5권3호
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    • pp.112-116
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    • 2005
  • This paper presents a broadband two-stage low noise amplifier(LNA) operating from 3 to 10 GHz, designed with 0.18 ${\mu}m$ RF CMOS technology, The cascode feedback topology and broadband matching technique are used to achieve broadband performance and input/output matching characteristics. The proposed UWB LNA results in the low noise figure(NF) of 3.4 dB, input/output return loss($S_{11}/S_{22}$) of lower than -10 dB, and power gain of 14.5 dB with gain flatness of $\pm$1 -dB within the required bandwidth. The input-referred third-order intercept point($IIP_3$) and the input-referred 1-dB compression point($P_{ldB}$) are -7 dBm and -17 dBm, respectively.

마이크로스트립 미앤더 선로의 신호 왜곡 현상 연구 (The Study on Signal Distortion of Meander-shaped Microstrip Line)

  • 두진경;홍영표;김정민;육종관
    • 한국전자파학회:학술대회논문집
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    • 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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    • pp.197-202
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    • 2005
  • In this paper, we analyzed the signal distortion incorporating meander-shaped transmission line on PCB in broadband frequency range, up to 50GHz. This broadband characteristic provides reasonable analysis of digital pulse having very short rising time. Simulation results reveal suppression characteristic at multiband which is dependent on only the width of meander arm. This width of arm also can be adjusted using different permittivity because it provides different effective wave-length. It is found that the suppression characteristic shows sharpness with as a function of the number of arms. However, these characteristics shown limitation for microstrip line structure rather than for stripline structure, so we can avoid these unwanted phenomena using stripline structure.

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광대역 무선 액세스 환경에서의 트래픽 특성분석 (Analysis of Traffic Characteristics in Broadband Wireless Access)

  • 구혜련;임석구
    • 한국콘텐츠학회:학술대회논문집
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    • 한국콘텐츠학회 2005년도 춘계 종합학술대회 논문집
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    • pp.346-351
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    • 2005
  • 인터넷의 급속한 보급과 대용량 멀티미디어 서비스에 대한 요구 증가로 댁내 또는 중소사업장에 대한 광대역 무선 액세스(Broadband Wireless Access) 수요가 증가하고 있다. 기존의 무선랜은 도달거리가 짧아서 이동 중일 때나 AP(Access Point)에서 멀어지면 통화품질이 저하되고, 무선인터넷은 사용 비용이 높다. 이를 보안한 광대역 무선 인터넷 시스템인 와이브로(WiBro: Wireless Broadband Internet)는 휴대폰과 무선랜의 중간 영역에 위치한 이동초고속인터넷서비스이다. 본 논문에서는 IEEE 802.16 BWA을 기반으로 멀티미디어 서비스를 제공하기 위해서 서비스별 트래픽 모델과 특성을 분석하고, 다양한 트래픽 혼합 비율에 따라 시뮬레이션을 수행하였으며, 이를 토대로 최종적으로는 WiBro 시스템에서 수용 가능한 최대 가입자 수를 산출하였다.

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넷 중립성의 경제적 특성과 시사점 (Economic Characteristics and Implications of Net Neutrality)

  • 송경석
    • 디지털융복합연구
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    • 제7권3호
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    • pp.1-11
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    • 2009
  • In this paper I examined economies and implications of "Net Neutrality" and Internet Freedom. It is argued that mandating Net Neutrality would be likely to reduce economic welfare. Instead, the government should focus on creating competition in the broadband market by liberalizing more spectrum and reducing entry barriers created by certain local regulations. In cases where a broadband provider can exercise market power the government should use its antitrust enforcement authority to police anti-competition behavior. To assure Net Neutrality, it is needed to make sure of fair competition and to facilitate flexible prices. Especially it is needed to invest consistently to the sector of Network.

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5GHz 무선랜 응용을 위한 소형 광대역 MEMS 안테나 (A Small Size Broadband MEMS Antenna for 5 GHz WLAN Applications)

  • 김지혁;김현철;전국진
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2006년도 하계종합학술대회
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    • pp.603-604
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    • 2006
  • A small size broadband microstrip patch antenna with small ground plane has been fabricated using MEMS. Multiple layer of high and low dielectric substrates are used to realize small size and broadband characteristics. The microstrip patch is divided into 4 pieces and each patch is connected to each other using a metal microstrip line. The fabrication process is very simple and only one mask is needed. Two types of microtrip antennas are fabricated. Type A is the microstrip antenna with metal lines and type B is the microstrip antenna without metal lines. The size of proposed microstip antenna is $8*12*2mm^3$ and the experimental results show that the antenna type A and type B have the bandwidth of 420MHz at 5.3 GHz and 480MHz at 5.66 GHz, respectively.

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이중대역 무선랜용 능동발룬 내장 광대역 믹서 설계 (Broadband Mixer with built-in Active Balun for Dual-band WLAN Applications)

  • 이강호;구경헌
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2005년도 추계종합학술대회
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    • pp.261-264
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    • 2005
  • This paper presents the design of a down-conversion mixer with built-in active balun integrated in a $0.25\;{\mu}m$ pHEMT process. The active balun consists of series-connected common-gate FET and common-source FET. The designed balun achieved broadband characteristics by optimizing gate-width and bias condition for the reduction in parasitic effect. From DC to more than 6GHz, the active balun shows the phase error of less than 3 degree and the gain error of less than 0.4 dB. A single-balanced down-conversion mixer with built-in broadband active balun has been designed with optimum width, load resistor and bias for conversion gain and without any matching component for broadband operating. The designed mixer whose size of including on-chip bias circuit is $1\;mm{\times}1\;mm$ shows the conversion gain of better than 7 dB from 2 GHz to 6 GHz and $P_{1dB}$ of -10 dBm at 5.8 GHz

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포크모양의 급전선로를 갖는 광대역 마이크로스트립 슬롯 안테나 설계 및 제작 (Design and Fabrication of a Broadband Microstrip Slot Antenna with a Fork-shaped Feedline)

  • 문영길;김흥수
    • 대한전자공학회논문지TC
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    • 제41권8호
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    • pp.87-92
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    • 2004
  • 본 논문에서는 포크 모양의 급전선로를 갖는 마이크로스트립 슬롯 안테나를 설계하고 제작하였다. 폭이 넓은 슬롯 안테나의 광대역 특성을 얻기 위해 급전선로를 포크 모양으로 변형하고, 슬롯의 크기와 옵셋 간격을 조정하였다. 이러한 설계 변수 변화에 따른 마이크로스트립 슬롯 안테나의 특성을 분석하여 광대역 마이크로스트립 슬롯 안테나를 설계하였다. 포크 모양의 급전선로를 갖는 마이크로스트립 슬롯 안테나를 제작하여 측정한 결과, VSWR≤2에 대해서 1.65 GHz에서 6.20 GHz까지의 광대역특성이 얻어졌다.

잡음환경에서 구름 볼 베어링의 결함검출을 위한 ALE의 적용 (Application of ALE for detection of rolling ball bearing defects in noisy environment)

  • 김영태;최만용;김기복;박해원;박정학;김종억;류준
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2004년도 추계학술대회 논문집
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    • pp.86-91
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    • 2004
  • It is very important to detect the bearing defects in rotating machinery since the critical failure of bearing cause a machinery shutdown. However it is difficult to detect the vibration signal resulting from the initial defects of bearing because of the high level of broadband noise. A signal processing technique, called the adaptive line enhancer(ALE) as one of adaptive filter, is studied in this work. This technique is to eliminate broadband noise without a prior knowledge of the noise and signal characteristics. Also we propose the optimal methods for selecting the three main ALE parameters such as correlation length, filter order and adaptation constant used in the adaptative process. Vibration signals for three abnormal bearings, including inner and outer raceways and ball defects, were acquired from Anderon(angular derivative of radius on)meter. The experimental results showed that the proposed technique can reliably detect the bearing defective signals masked by broadband noise.

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