• Title/Summary/Keyword: low bandwidth

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Design of Thomson Scattering System Using VPH Grating for Plasma Processing

  • Joa, Sang-Beom;Ko, Min-Guk;Kang, In-Je;Yang, Jong-Keun;Yu, Yong-Hun;Lee, Heon-Ju
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.525-525
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    • 2013
  • Low temperature plasma diagnosis is one of the big issues in laboratory scale or processing industry. One of the most powerful techniques of plasma diagnostics is the use of the scattering of electromagnetic radiation from the plasma. Electron temperature and density are important parameters for understanding the information of plasmas in the plasma processing industry. Laser scattering experiments on plasma can provide a substantial amount of information about plasma parameters such as the electron density ne, the electron temperature Te, and the neutral density nn and temperature Tn. Thomson scattering spectroscopy is used several method, in accordance with detector type. Commonly, Thomson scattering is used several notch filter to separate expanded wavelength. Since using a spectrometer with surface relief grating or notch filter, the system of the measurement will be complicated and bigger. In this study, using VPHG (Volume Phase Holographic Grating) in order to install the simple and cheap system. VPHG has the advantage of the system installation, because it can be Transmission Type. The diffraction efficiency and dispersion angle of VPHG is higher than the surface relief grating relatively. For a wavelength and bandwidth selection, Using a slit or mask to select a rejection wavelength instead of notch filter.

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Studies on S-band Broadband Amplifier using compensated matching network (정합회로 보상 방법을 이용한 S-밴드용 광대역 증폭기 연구)

  • Kim, Jin-Sung;An, Dan;Rhee, Jin-Koo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.6
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    • pp.247-252
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    • 2003
  • In this paper, we have designed and fabricated a broadband 2-stage MMIC amplifier. Broadband characteristics could be obtained by compensated matching networks in a 2-stage amplifier design. This method is compensating low gains at lower frequencies in the 1st-stage with higher gains at lower frequencies in the 2nd- stage and then finally flat gains are obtained in the wide frequency ranges. Also, we have obtained not only broadband characteristics but also high gain using compensation matching network. The fabricated amplifier is measured by attaching on the test PCB(Printed Circuits Board). The measurement results are bandwidth of 1.1~2.8 GHz, S$_{21}$ gain of 11.1$\pm$0.3 ㏈ and P1㏈ of 12.6 ㏈m at 2.4 GHz.

Implementation of Various FIR Filters using Constrained Least Square Criterion (제한된 최소 자승 오차 기준에 의한 다양한 FIR 필터 구현)

  • Hong, Seung-Eok;Kim, Joong-Kyu
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.10
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    • pp.175-185
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    • 1998
  • In this paper, we studied some design methodologies of typical FIR filters based on the peak-error constrained least square criterion which was first introducedd by Adams in 1991. This method is a mixed type of the classical least squared error method(LSM) and the so-called min-max error method (MMM). And by considering both the least squared error as well as the maximum error, the solution, i.e. the impulse response of the filter, can be found only when the restrictions on maximum gain, transition bandwidth, and the squared error are satisfied simultaneously under some trade-off conditions. We used the multiple exchange algorithms for optimization procedure and applied the design methodology to the cases of the multiband filter, the differentiator, and the Hilbert transformer by taking the balance of two design criteria into account. The results show that the peak-error constrained least weighted square error design method(PLEM) is superior in performance to the existing LSM and MMM from both the squared error and the maximum error standpoints. And it is verified that PLEM can be applied to not only the case of simple low pass filter, but also to various types of FIR filters.

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Design and Performance of Linear Clock Fair Queueing Algorithm (LCFQ ( Linear Clock Fair Queueing ) 알고리즘의 설계와 성능 분석)

  • Kim, Young-Han;Lee, Jae-Yong
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.36S no.1
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    • pp.1-8
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    • 1999
  • In order to provide appropriate Quality of Service(QoS) guarantee to each traffic flow in intergrated service networks, an efficient traffic scheduling algorithm as well as resource reservation must be adopted in host and transit routers. In this paper, a new efficient fair queueing algorithm which adopts a linearly increasing virtual time is presented. The proposed algorithm is fair and the maximum and mean delay guaranteed of each flow are less than those of the SCFQ(self clocked fair queueing) algorithm which is one of the most promising traffic scheduling algorithm, while providing low implementation complexity as the SCFQ scheme. And, it has the better isolation provided than SCFQ, which means that each flow is much less influenced by the violating traffic flows provided its allocated bandwidth gurantee. The fairness of the proposed algorithm is proved and simulation results of maximum and mean delay presented.

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A Weight based GTS Allocation Scheme for Fair Queuing in IEEE 802.15.4 LR-WPAN (IEEE 802.15.4 LR-WPAN 환경에서 공정 큐잉을 위한 가중치 기반 GTS 할당 기법)

  • Lee, Kyoung-Hwa;Lee, Hyeop-Geon;Shin, Yong-Tae
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.9
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    • pp.19-28
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    • 2010
  • The GTS(Guaranteed Time Slot) of the IEEE 802.15.4 standard, which is the contention free access mechanism, is used for low-latency applications or applications requiring specific data bandwidth. But it has some problems such as delay of service due to FIFS(First In First Service) scheduling. In this paper, we proposes a weight based GTS allocation scheme for fair queuing in IEEE 802.15.4 LR-WPAN. The proposed scheme uses a weight that formed by how much more weight we give to the recent history than to the older history for a new GTS allocation. This scheme reduces service delay time and also guarantees transmission simultaneously within a limited time. The results of the performance analysis shows that our approach improves the performance as compared to the native explicit allocation mechanism defined in the IEEE 802.15.4 standard.

Dual Bias Modulator for Envelope Tracking and Average Power Tracking Modes for CMOS Power Amplifier

  • Ham, Junghyun;Jung, Haeryun;Bae, Jongsuk;Lim, Wonseob;Hwang, Keum Cheol;Lee, Kang-Yoon;Park, Cheon-Seok;Yang, Youngoo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.6
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    • pp.802-809
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    • 2014
  • This paper presents a dual-mode bias modulator (BM) for complementary metal oxide semiconductor (CMOS) power amplifiers (PAs). The BM includes a hybrid buck converter and a normal buck converter for an envelope tracking (ET) mode for high output power and for an average power tracking (APT) mode for low output power, respectively. The dual-mode BM and CMOS PA are designed using a $0.18-{\mu}m$ CMOS process for the 1.75 GHz band. For the 16-QAM LTE signal with a peak-to-average power ratio of 7.3 dB and a bandwidth of 5 MHz, the PA with the ET mode exhibited a poweradded efficiency (PAE) of 39.2%, an EVM of 4.8%, a gain of 19.0 dB, and an adjacent channel leakage power ratio of -30 dBc at an average output power of 22 dBm, while the stand-alone PA has a PAE of 8% lower at the same condition. The PA with APT mode has a PAE of 21.3%, which is an improvement of 13.4% from that of the stand-alone PA at an output power of 13 dBm.

The Characteristic Analysis of Microstrip Slot antennal with T-Shaped Feed Line (T-모양 급전선을 갖는 마이크로스트립 슬롯 안테나의 특성 분석)

  • 장용웅;윤종철;박익모;신철재
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.5
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    • pp.630-639
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    • 1998
  • In this paper, a T-shaped microstrip feed line is proposed for a better impedance matching to the microstrip slot antenna in a various range of slot widths. It was found that the bandwidth of this antenna is proportional to the slot width. It was also found that the radiation resistance of this feed line structure is quite constant and low regardless to the slot width. A slot antenna with T-shaped microstrip feed line is analyzed by using the FDTD method. At first, the propagation process of the reflected wave and the electric field distribution in the time domain is calculated respectively. The antenna parameters also are optimized to get maximum band width, return loss, input impedance, and radiation pattern in the frquency domain by Fourier transforming the time domain results. From the computed results, the optimum slot antenna is designed and fabricated. When the slot width is 16 mm, approximately 35% of bandwidths are obtained without a matching circuit. These computed results using FDTD method were in relatively good accordance with the measured values.

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Measurement and Analysis of Electric Filed Distributions under 154[kV] Overhead Tranamission Lines (154[KV] 가공송전선로 아래에서 전장분포의 측정과 분석)

  • 이복희;이정기;안창환;이경옥;박동화;곽희로;송진호
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.11 no.1
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    • pp.92-98
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    • 1997
  • In this paper, the results of the measurement and analysis of extremely low freqency(ELF) eletric field in the vicinity of 154[kV] overhad transmission lines have been described. The planar-type electric field sensor has been fabricated by three dimensional structure with special consideration of taking the power frequency and lower components. The calibration experiments have been carried out according to the procedures of IEEE recommendation. The electric field measuring system has the frequency bandwidth of 7[Hz] to 2.7[MHz] and the response sensitivity of 0.094[mV/V/m]. Also the practical measurements of electric field under an 154[kV] double corcuit overhead transmission lines have been made abd abalyzed. It was known that the lateral electric field profiles under an 154[kV] double circuit overhead transmission lines show the asymmetrical distributions owing to the environmental metal frame structures and their maximum electric field magnitude is less than 3[kV/m]. It can be concluded that the measured results of the electric fields satisfy with all limits or guide -lines of the various authorized international institutes' recommendations.

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도로터널 조명시설의 설계기준

  • 지철근;이진우
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.11 no.1
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    • pp.14-23
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    • 1997
  • In this paper, the results of the measurement and analysis of extremely low frequency(ELF) electric field in the vicinity of 154[kV] overhead transmission lines have been described. The planar-type electric field sensor has been fabricated by three dimensional structure with special consideration of taking the power frequency and lower components. The calibration experiments have been carried out according to the procedures of IEEE recommendation. The electric field measuring system has the frequency bandwidth of 7[Hz] to 2.7[MHz] and the response sensitivity of 0.094[mV/V/m]. Also the practical measurements of electric field under an 154[kV] double circuit overhead transmission lines have been made and analyzed. It was known that the lateral electric field profiles under an 154[kV] double circuit overhead transmission lines show the asymmetrical distributions owing to the environmental metal frame structures and their maximum electric field magnitude is less than 3[kV/m]. It can be concluded that the measured results of the electric fields satisfy with all limits or guidelines of the various authorized international institutes' recommendations.

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Prefetching Methods with Vehicle's Pattern in Location-Based Services (위치기반서비스에서 차량의 패턴을 고려한 프리페칭 기법)

  • Choi, In-Seon;Kim, Joo-Hwan;Lee, Dong-Chun
    • Convergence Security Journal
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    • v.8 no.4
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    • pp.105-113
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    • 2008
  • Mobile computing environment is known to be quite difficult to provide user with a stable Quality of Service (QoS) due to vehicle mobility nature. In order to protect the inherent characteristics of wireless network such as low bandwidth and high transmission delay along with the vehicle's mobility, many works are conducted to apply caching and prefetching methods. This paper presents a novel prefetching technique which is based on owner's profile. It is the scheme with the vehicle velocity, the visit frequency and resident time of specific region for vehicle owner's past given period, and the user profile which has owner's personal inclination about a certain place. The proposed scheme shown relatively superior performance in terms of the utilization ratio of prefetched information and the failure ratio of information retrieval than the previous methods.

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