• Title/Summary/Keyword: wave environments

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Optimal Threshold Setting Method for R Wave Detection According to The Sampling Frequency of ECG Signals (심전도신호 샘플링 주파수에 따른 R파 검출 최적 문턱치 설정)

  • Cho, Ik-sung;Kwon, Hyeog-soong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.7
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    • pp.1420-1428
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    • 2017
  • It is difficult to guarantee the reliability of the algorithm due to the difference of the sampling frequency among the various ECG databases used for the R wave detection in case of applying to different environments. In this study, we propose an optimal threshold setting method for R wave detection according to the sampling frequency of ECG signals. For this purpose, preprocessing process was performed using moving average and the squaring function based the derivative. The optimal value for the peak threshold was then detected according to the sampling frequency by changing the threshold value according to the variation of the signal and the previously detected peak value. The performance of R wave detection is evaluated by using 48 record of MIT-BIH arrhythmia database. When the optimal values of the differential section, window size, and threshold coefficient for the MIT-BIH sampling frequency of 360 Hz were 7, 8, and 6.6, respectively, the R wave detection rate was 99.758%.

Coverage Evaluation of mmWave Small Cell in Outdoor Environment (실외환경에서 밀리미터파 소형 셀의 커버리지 측정)

  • Nguyen, Thanh Ngoc;Jeon, Taehyun
    • Journal of Satellite, Information and Communications
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    • v.12 no.4
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    • pp.162-165
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    • 2017
  • In an effort to compensate the rising of the data throughput demand nowadays, there have been many research works to optimize the radio resource and increase the capacity of the network. At the present, small cell network, mmWave band and beamforming technology are leading the trend and becoming the core solutions of the fifth generation (5G) cellular networks. Since the propagation characteristics of radio wave in the mmWave band is quite different from the conventional bands, the communication systems which work in these bands have to be redesigned. In this paper, a 3D simulation model is discussed for cellular network at 60 GHz in outdoor environments. Coverage analysis and system performance is carried out for a small cell system in the typical urban environment including street canyon simulation scenario. In addition, the beamforming technique is considered to evaluate the throughput improvement. Simulation results show that the mmWave small cell systems is expected to be one of the major candidate technologies to satisfy the requirements of 5G in terms of data rate.

A Development of the High-Performance Signal Processor for the Compact Millimeter Wave Radar (소형 밀리미터파 레이더를 위한 고성능 신호처리기 개발)

  • Choi, Jin-Kyu;Ryu, Han-Chun;Park, Seung-Wook;Kim, Ji-Hyun;Kwon, Jun-Beom
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.6
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    • pp.161-167
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    • 2017
  • Recently, small radar has been reduced in size and power consumption to cope with various operating environments. It also requires the development of a small millimeter wave radar with high range resolution to disable the system of target with a single strike. In this paper, we design and implement a signal processor that can be used in small millimeter wave radar. The signal processor for the small millmeter wave radar is designed with a digital IF(Intermediate Frequency) receiver and DFT(Discrete Fourier Transform) module capable of real time FFT operation for miniaturization and low power consumption. Also it was to leverage the FPGA(Field Programmable Gate Array) and DAC(Digital Analog Converter) as a means for correcting the distortion of signals that can occur in the receive path of the small millimeter wave radar to create a RF signal that is used by the system. Finally, we verified the signal processor presented through performance test

A Study on the Effects of Electromagnetic Wave on Human Body - The Variation of Electroencephalogram by Blocking Electromagnetic Wave Materials and Aural Stimuli - (전자파가 인체에 미치는 영향 - 전자파 차폐소재와 청각자극에 나타난 뇌파전위의 변화 -)

  • Lee, Su-Jeong;Lee, Tae-Il
    • Fashion & Textile Research Journal
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    • v.6 no.4
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    • pp.503-510
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    • 2004
  • The study is one of fundamental researches for the development of future smart clothing and textile products with blocking properties from electromagnetic waves by analyzing human physical symptoms in using electromagnetic products in such an environments. Among various textiles in the experiment, nano silver has shown the best blocking performance from electromagnetic waves, which decreases depending on the distance. The power spectrum distribution and the incidence of electroencephalogram between blocking materials and aural stimuli has shown that, ${\beta}$, wave appeared to be active in all channels except for $T_4$, whereas all waves appeared with processed materials and especially with nano silver silk(NSS), ${\alpha}$, ${\beta}$, ${\theta}$, ${\gamma}$ waves appeared active in all regions. As for the brain mapping of ${\alpha}$ wave according to time, there found a strong activity in $P_3$, $P_4$ of the parietal lobe, with all materials on all time regions. With silk nylon metal(SNM) and NSS, it appeared strong in $F_3$, $F_4$ as well. As for ${\beta}$, wave, the activity appeared strong in frontal lobe before 7min. 30sec, where it tends to diminish abruptly in 7min. 30sec. to 13min. 30sec. region. After 13min., it regained gradually. With NSS, it appeared strong in all areas except for the farthest $T_4$. The appearance of ${\nu}$ wave can be deduced as it can affect human body with its toxic property while the silver particles become nano-sized. Therefore, the study conducted with human participants requires a proper particle size of it which would not penetrate cellular tissues and a proper binder and binding treatment for it, to prevent the physical fatigues and the potential diseases. However, it is highly required for back-up researches to verify various aspects in applying nano silver to textile products.

New Diagnostic Technique and Device for Lightning Arresters by Analyzing the Wave Height Distribution of Leakage Currents (누설전류의 파고분포 분석에 의한 새로운 피뢰기 진단기술 및 장치)

  • 길경석;한주섭;송재영;조한구;한문섭
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.12
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    • pp.562-567
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    • 2003
  • Lightning arresters are deteriorated by repetition of protective operation against overvoltages or impulse currents in environments of its use. If a deteriorated arrester is left in power lines, it can lead to an accident such as a line to ground fault even in a normal system. Therefore, it is necessary to eliminate the deteriorated arrester in advance by checking the soundness of arresters on a regular basis, and to ensure the reliability of power systems by preventing accidents. Various deterioration diagnostic techniques and devices are suggested, and most of which measure leakage current components as an indicator of arrester ageing. However, the techniques based on the magnitude of leakage current measure simply RMS or peak value of leakage current components and do not provide detailed information needed in the diagnosis. In this study, we found that the wave height distributions of the total leakage currents are remarkably changed or a new wave height are produced with the progress of arrester deterioration. To propose a new technique for the diagnosis, we designed a leakage current detection unit and an analysis program which can measure leakage current magnitudes and analyze wave height distributions. From the experimental results, we confirmed that the proposed technique by analyzing the wave height distribution can simply diagnose the mode of defects such as a partial damage and an existence of punctures in arresters as well as deterioration of arresters.

An efficient shear deformation theory for wave propagation of functionally graded material plates

  • Boukhari, Ahmed;Atmane, Hassen Ait;Tounsi, Abdelouahed;Adda Bedia, E.A.;Mahmoud, S.R.
    • Structural Engineering and Mechanics
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    • v.57 no.5
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    • pp.837-859
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    • 2016
  • An efficient shear deformation theory is developed for wave propagation analysis of an infinite functionally graded plate in the presence of thermal environments. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The thermal effects and temperature-dependent material properties are both taken into account. The temperature field is assumed to be a uniform distribution over the plate surface and varied in the thickness direction only. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton's principle and the physical neutral surface concept. There is no stretching.bending coupling effect in the neutral surface-based formulation, and consequently, the governing equations and boundary conditions of functionally graded plates based on neutral surface have the simple forms as those of isotropic plates. The analytic dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions and temperature on wave propagation of functionally graded plate are discussed in detail. It can be concluded that the present theory is not only accurate but also simple in predicting the wave propagation characteristics in the functionally graded plate. The results carried out can be used in the ultrasonic inspection techniques and structural health monitoring.

A Determination Model of the Data Transmission-Interval for Collecting Vehicular Information at WAVE-technology driven Highway by Simulation Method (모의실험을 이용한 WAVE기반 고속도로 차량정보 전송간격 결정 모델 연구)

  • Jang, Jeong-Ah;Cho, Han-Byeog;Kim, Hyon-Suk
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.9 no.4
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    • pp.1-12
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    • 2010
  • This paper deals with the transmission interval of vehicle data in smart highway where WAVE (Wireless Access for Vehicular Environments) systems have been installed for advanced road infrastructure. The vehicle data could be collected at every second, which is containing location information of the vehicle as well the vehicle speed, RPM, fuel consuming and safety data. The safety data such as DTC code, can be collected through OBD-II. These vehicle data can be used for valuable contents for processing and providing traffic information. In this paper, we propose a model to decide the collection interval of vehicle information in real time environment. This model can change the transmission interval along with special and time-variant traffic condition based on the 32 scenarios using microscopic traffic simulator, VISSIM. We have reviewed the transmission interval, communication transmission quantity and communication interval, tried to confirm about communication possibility and BPS, etc for each scenario. As results, in 2-lane from 1km highway segment, most appropriate transmission interval is 2 times over spatial basic segment considering to communication specification. In the future, if a variety of wireless technologies on the road is introduced, this paper considering not only traffic condition but also wireless network specification will be utilized the high value.

Performance Evaluation of V2X Communication System Under a High-Speed Driving (고속 주행 환경에서의 V2X 통신 성능 측정 시스템)

  • Kang, Bo-young;Bae, Jeongkyu;Seo, Woo-Chang;Park, Jong Woo;Yang, EunJu;Seo, Dae-Wha
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.5
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    • pp.1069-1076
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    • 2017
  • C-ITS(Cooperative-Intelligent Transportation System) provides services that require strict real-time such as forward collision warning, road safety service and emergency stop. WAVE(Wireless Access in Vehicular Environments), a core technology of C-ITS, is a technology designed for high-speed driving. However, in order to provide stable communication service by applying to real road environment, various performance tests of real vehicular environment are required. In the real road environment, WAVE communication performance is influenced by the surrounding environment such as moving vehicle, road shape and topography. Especially, when the vehicle is moving at high speed, the traveling position according to the speed of the vehicle, The surrounding environment changes rapidly. Such changes are factors affecting the communication performance, therefore a system and methods for analyzing them are needed. In this paper, we propose the configuration and test method of an effective performance evaluation system under high-speed driving and describe the results of analyzing the communication performance based on the data measured through the actual vehicle test.

Plane-wave Full Waveform Inversion Using Distributed Acoustic Sensing Data in an Elastic Medium (탄성매질에서의 분포형 음향 센싱 자료를 활용한 평면파 전파형역산)

  • Seoje, Jeong;Wookeen, Chung;Sungryul, Shin;Sumin, Kim
    • Geophysics and Geophysical Exploration
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    • v.25 no.4
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    • pp.214-216
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    • 2022
  • Distributed acoustic sensing (DAS), an increasingly growing acquisition technique in the oil and gas exploration and seismology fields, has been used to record seismic signals using optical cables as receivers. With the development of imaging methods for DAS data, full waveform inversion (FWI) is been applied to DAS data to obtain high-resolution property models such as P- and S-velocity. However, because the DAS systems measure strain from the phase distortion between two points along optical cables, DAS data must be transformed from strain to particle velocity for FWI algorithms. In this study, a plane-wave FWI algorithm based on the relationship between strain and horizontal particle velocity in the plane-wave assumption is proposed to apply FWI to DAS data. Under the plane-wave assumption, strain equals the horizontal particle velocity, which is scaled by the velocity at the receiver position. This relationship was confirmed using a numerical experiment. Furthermore, 4-layer and modified Marmousi-2 velocity models were used to verify the applicability of the proposed FWI algorithm in various survey environments. The proposed FWI was implemented in land and marine survey environments and provided high-resolution P- and S-velocity models.

Performance Verification of WAVE Communication Technology for Railway Application (차량용 무선통신기술(WAVE)의 철도 적용을 위한 성능검증)

  • Kim, Keum-Bee;Ryu, Sang-Hwan;Choi, Kyu-Hyoung
    • Journal of the Korean Society for Railway
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    • v.19 no.4
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    • pp.456-467
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    • 2016
  • Wireless Access in Vehicular Environments (WAVE) communication technology, which provides vehicleto-vehicle and vehicle-to-infrastructure communication and offers safe and convenient service, has been developed for application to an Intelligent Transport System (ITS). This paper provides field test results on a study of the feasibility of WAVE technology application to railway communication systems. A test railway communication system based on WAVE technology has been built along the Daebul line and a newly developed EMU. Field tests have been carried out according to the communication function requirements for LTE - R. The test results show that the railway communication system based on WAVE technology meets the functional requirements: maximum transmission length is 730m, maximum transfer delay is 5.69ms, and maximum interruption time is 1.36s; other tests including throughput test, video data transmission test, VoIP data test, and channel switching test also produced results that meets the functional requirements. These results suggest that WAVE technology can be applied to the railway communication system, enabling Vehicle-to-Wayside communication.