• Title/Summary/Keyword: Over-modulation

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Implementation of An 1.5Gbit/s Wireless Data Transmission System at 300GHz Band (300GHz 대역 1.5Gbit/s 무선 데이터 전송 시스템 구현)

  • Lee, Won-Hui;Chung, Tae-Jin
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.11 no.2
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    • pp.1-6
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    • 2011
  • In this paper, an 1.5Gbit/s wireless data transmission system using the carrier frequency of 300 GHz band was implemented. The RF front-end was composed of schottky diode sub-harmonic mixer, frequency tripler, and horn antennas for transmitter and receiver, respectively. The LO frequencies of sub-harmonic mixer are 150GHz for transmit chain and 156GHz for receive chain. The ASK(Amplitude Shift Keying) modulation was used in the transmitter and the envelope detection method was used in the heterodyne receiver. The conversion loss of sub-harmonic mixer and implementation system loss were measured to be 9.8dB and 1.2dB, respectively. The 1.5Gbit/s video signal with HD-SDI format was transmitted over wireless distance of 40cm without optical lens(4.2m with optical lens) and displayed on HDTV at the transmitted average output power of $20{\mu}W$.

Enhanced Wireless Network Security in Military Environments (군사 환경에서의 향상된 무선 네트워크 보안)

  • Kim, Jin Woo;Shin, Soo Young
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.11
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    • pp.1341-1348
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    • 2016
  • In this paper, we propose method to enhance security performance using HT-STBC with artificial noise under Wier-Tap channel model that exist with legitimate receiver and illegal eavesdropper. Conventional STBC with artificial noise scheme has a weakness that a limited increase in the BER of the difference between the receiver and an eavesdropper, when used over QPSK modulation. To solve this problem, we suggest HT-STBC combining hadamard transform and STBC with artificial noise for reduce BER of receiver than the conventional scheme and demonstrated through simulation that also increased BER difference between the receiver and an eavesdropper. By the simulation results, when used proposed scheme, showed approximately 3dB improvement in performance compared to the conventional scheme.

Ascophyllum nodosum and its symbionts: XI. The epiphyte Vertebrata lanosa performs better photosynthetically when attached to Ascophyllum than when alone

  • Garbary, David J.;Miller, Anthony G.;Scrosati, Ricardo A.
    • ALGAE
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    • v.29 no.4
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    • pp.321-331
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    • 2014
  • Vertebrata lanosa is an abundant and obligate red algal epiphyte of Ascophyllum nodosum that forms part of a complex and highly integrated symbiotic system that includes the ascomycete, Mycophycias ascophylli. As part of ongoing studies to resolve interactions among species in the symbiosis, we used pulse amplitude modulation fluorimetry of chlorophyll a fluorescence, from photosystem II (PSII), to measure the maximum quantum yield ($F_v/F_m$) of PSII [$QY(II)_{max}$] and relative photosynthetic electron transport rates (rETR), as a function of light intensity, in order to evaluate the photosynthetic capacity of the two algal symbionts in the field and in the laboratory under different treatments. Our primary question was 'Is the ecological integration of these species reflected in a corresponding physiological integration involving photosynthetic process?' In the laboratory we measured changes in $QY(II)_{max}$ in thalli of V. lanosa and A. nodosum over one week periods when maintained together in either attached or detached treatments or when maintained separated from each other. While the $QY(II)_{max}$ of PSII of A. nodosum remained high and showed no significant variation among treatments, V. lanosa showed decreasing performance in the following conditions: V. lanosa attached to A. nodosum, V. lanosa in the same culture, but not attached to A. nodosum, and V. lanosa alone. These results are consistent with observations in which rETR was reduced in V. lanosa maintained alone versus attached to A. nodosum. Values for $QY(II)_{max}$ in V. lanosa measured in the field in fully submerged thalli were similar to those measured in the laboratory when V. lanosa was attached to it obligate host A. nodosum. Our results provide evidence of a physiological association of the epiphyte and its host that reflects the known ecology.

RF Interconnection Technique of MMIC Microwave Switch Matrix for 60 dB On-to-off Isolation (60 dB 온-오프 격리도를 위한 통신 위성 중계기용 MMIC MSM의 RF 결합 방법)

  • Noh Youn-Sub;Jang Dong-Pil;Yom In-Bok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.2 s.105
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    • pp.134-138
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    • 2006
  • The isolation performance of the S-band single-pole single-throw(SPST) monolithic microwave integrated circuit (MMIC) switch with two different RF-interconnection approaches, microstrip and grounded coplanar waveguide(GCPW) lines, are investigated. On-to-off isolation is improved by 5.8 dB with the GCPW design compared with the microstrip design and additional improvement of 6.9 dB is obtained with the coplanar wire-bond interconnection(CWBI) at a 3.4 GHz. The measured insertion loss and third-order inter-modulation distortion(IMD3) are less than 1.94 dB over $3.2{\sim}3.6\;GHz$ and greater than 64 dBc.

Modulation of Bee Venom on Th1/Th2 Cell Lineage Development (봉독 추출액이 helper T cell 분화에 미치는 영향)

  • Ko Eun Jung;Nam Sang Soo;Hong Moo Chang;Shin Min Kyu;Bae Hyun Su
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.18 no.5
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    • pp.1347-1355
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    • 2004
  • In this study, the immunological effect of a traditional Korea herbal acupuncture, that has been widely used for the treatment of various immunological disorders including inflammation in Korea, was examined in vitro and in vivo. In our previous study demonstrated that BV increased the expression of IFN-γ mRNA, that plays pivotal role in T cell response. This study was designated to evaluate the effect of BV on helper T cell development by monitoring Th1/Th2 specific cytokine secretion patterns in artificially induced Th1/Th2 polarized condition and in vivo. The results demonstrated that BV didn't have mitogenic effects on the unstimulated CD4+ T cell, but increased the CD4+ T cell proliferation upon activation with anti-CD3/CD28 antibody. The Th1 cells were over-populated dramatically in Th1 driven condition with BV treatment, while the Th2 cells were increased slightly in Th2 skewed condition. Furthermore, under Th1-skewed conditions, the level of IFN-γ was considerably increased with BV treatment. Besides, the expression of T-bet, a transcription factor that plays pivotal role in Th1 lineage programming, was increased with BV treatment. The expressions of IFN-γ and T-bet were also significantly increased in vivo. The results that Th1 specific cytokine secretion were considerably increased and Th2 specific cytokine secretion were not significantly changed in vitro and in vivo indicated that BV enhances Th1 lineage development, Therefore, these results suggest that BV might be desirable agent for correction of Th1 dominant pathological disorders.

Ochnaflavone, a Natural Biflavonoid, Induces Cell Cycle Arrest and Apoptosis in HCT-15 Human Colon Cancer Cells

  • Kang, You-Jin;Min, Hye-Young;Hong, Ji-Young;Kim, Yeong-Shik;Kang, Sam-Sik;Lee, Sang-Kook
    • Biomolecules & Therapeutics
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    • v.17 no.3
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    • pp.282-287
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    • 2009
  • Ochnaflavone is a natural biflavonoid and mainly found in the caulis of Lonicera japonica (Caprifoliaceae). Biological activities such as anti-inflammatory and anti-atherogenic effects have been previously reported. The anticancer activity of ochnaflavone, however, has been poorly elucidated yet. In the present study, we investigated the effect of ochnaflavone on the growth inhibitory activity in cultured human colon cancer cell line HCT-15. Ochnaflavone inhibited the proliferation of the cancer cells with an $IC_{50}$ value of $4.1{\mu}M$. Flow cytometric analysis showed that ochnaflavone arrested cell cycle progression in the G2/M phase, and induced the increase of sub-G1 peak in a concentration-dependent manner. Induction of cell cycle arrest was correlated with the modulation of the expression of cell cycle regulating proteins including cdc2 (Tyr15), cyclin A, cyclin B1 and cyclin E. The increase of sub-G1 peak by the higher concentrations of ochnaflavone (over $20{\mu}M$) was closely related to the induction of apoptosis, which was evidenced by the induction of DNA fragmentation, activation of caspase-3, -8 and -9, and cleavage of poly-(ADP-ribose) polymerase. These findings suggest that the cell cycle arrest and induction of apoptosis might be one possible mechanism of actions for the anti-proliferative activity of ochnaflavone in human colon cancer cells.

Underwater Channel Analysis and Transmission Method Research via Coded OFDM (수중채널 분석과 Coded OFDM을 통한 전송방법 연구)

  • Jeon, Hyeong-Won;Lee, Su-Je;Lee, Heung-No
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5B
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    • pp.573-581
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    • 2011
  • The underwater channel is known to offer poor communications channel. The channel medium is highly absorptive and the transmission bandwidth is limited. In addition, the channel is highly frequency selective; the degree of selectiveness depends on a detailed geometry of the channel. Furthermore, the response changes over time as the channel conditions affecting the response such as water temperature, sea surface wind and salinity are time-varying. The transceiver design to deal with the frequency and time selective channel, therefore, becomes very challenging. It has been known that deep fading at certain specific sub-carriers are detrimental to OFDM systems. To mitigate this negative effect, the proposed coded OFDM system employs an LDPC code based modulation. In this paper, we aim 1) to provide a detailed underwater channel model; 2) to design a robust LDPC coded OFDM system; 3) to test the proposed system under a variety of channel conditions enabled by the channel model.

Efficient Link Adaptation Scheme using Precoding for LTE-Advanced Uplink MIMO (LTE-Advanced에서 프리코딩에 의한 효율적인 상향링크 적응 방식)

  • Park, Ok-Sun;Ahn, Jae-Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.2B
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    • pp.159-167
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    • 2011
  • LTE-Advanced system requires uplink multi-antenna transmission in order to achieve the peak spectral efficiency of 15bps/Hz. In this paper, the uplink MIMO system model for the LTE-Advanced is proposed and an efficient link adaptation shceme using precoding is considered providing error rate reduction and system capacity enhancement. In particular, the proposed scheme determines a transmission rank by selecting the optimal wideband precoding matrix, which is based on the derived signal-to-interference and noise ratio (SINR) for the minimum mean squared error (MMSE) receivers of $2{\times}4$ multiple input multiple output (MIMO). The proposed scheme is verified by simulation with a practical MIMO channel model. The simulation results of average block-error-rate(BLER) reflect that the gain due to the proposed rank adapted transmission over full-rank transmission is evident particularly in the case of lower modulation and coding scheme (MCS) and high mobility, which means the severe channel fading environment.

A Study on Image Resolution Increase According to Sequential Apply Detector Motion Method and Non-Blind Deconvolution for Nondestructive Inspection (비파괴검사를 위한 검출기 이동 방법과 논블라인드 디컨볼루션 순차 적용에 따른 이미지 해상도 증가 연구)

  • Soh, KyoungJae;Kim, ByungSoo;Uhm, Wonyoung;Lee, Deahee
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.6
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    • pp.609-617
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    • 2020
  • Non-destructive inspection using X-rays is used as a method to check the inside of products. In order to accurately inspect, a X-ray image requires a higher spatial resolution. However, the reduction in pixel size of the X-ray detector, which determines the spatial resolution, is time-consuming and expensive. In this regard, a DMM has been proposed to obtain an improved spatial resolution using the same X-ray detector. However, this has a limitation that the motion blur phenomenon, which is a decrease in spatial resolution. In this paper, motion blur was removed by applying Non-Blind Deconvolution to the DMM image, and the increase in spatial resolution was confirmed. DMM and Non-Blind Deconvolution were sequentially applied to X-ray images, confirming 62 % MTF value by an additional 29 % over 33 % of DMM only. In addition, SSIM and PSNR were compared to confirm the similarity to the 1/2 pixel detector image through 0.68 and 33.21 dB, respectively.

Sensorless Detection of Position and Speed in Brushless DC Motors using the Derivative of Terminal Phase Voltages Technique with a Simple and Versatile Motor Driver Implementation

  • Carlos Gamazo Real, Jose;Jaime Gomez, Gil
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1540-1551
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    • 2015
  • The detection of position and speed in BLDC motors without using position sensors has meant many efforts for the last decades. The aim of this paper is to develop a sensorless technique for detecting the position and speed of BLDC motors, and to overcome the drawbacks of position sensor-based methods by improving the performance of traditional approaches oriented to motor phase voltage sensing. The position and speed information is obtained by computing the derivative of the terminal phase voltages regarding to a virtual neutral point. For starting-up the motor and implementing the algorithms of the detection technique, a FPGA board with a real-time processor is used. Also, a versatile hardware has been developed for driving BLDC motors through pulse width modulation (PWM) signals. Delta and wye winding motors have been considered for evaluating the performance of the designed hardware and software, and tests with and without load are performed. Experimental results for validating the detection technique were attained in the range 5-1500 rpm and 5-150 rpm under no-load and full-load conditions, respectively. Specifically, speed and position square errors lower than 3 rpm and between 10º-30º were obtained without load. In addition, the speed and position errors after full-load tests were around 1 rpm and between 10º-15º, respectively. These results provide the evidence that the developed technique allows to detect the position and speed of BLDC motors with low accuracy errors at starting-up and over a wide speed range, and reduce the influence of noise in position sensing, which suggest that it can be satisfactorily used as a reliable alternative to position sensors in precision applications.