• Title/Summary/Keyword: Burst Duration

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An Analysis of the HEMP Interference Effect in OFDM System (OFDM 시스템에 미치는 HEMP 간섭 영향 분석)

  • Seong, Yun-Hyeon;Chang, Eun-Young;Yoon, Seok-beom
    • Journal of Advanced Navigation Technology
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    • v.19 no.3
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    • pp.244-249
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    • 2015
  • High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

A Study on a Multichannel(128) Ultrasound Pulsed Doppler System with Serial Data Processing for Sensing the Blood Flow (혈류 진단을 위하여 직렬데이터 처리를 하는 다중(128) 채널 초음파 펄스 도플러 시스템에 관한 연구)

  • Kim, Young-Kil
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.23 no.3
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    • pp.389-396
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    • 1986
  • A pulsed ultrasonic doppler flowmeter for mesurements of velocity profils in man is described. The device projects a beam of ultrasound in burst of 570 ns duration at 3.5 MHz. The back-scattered signals are processed to produce a signal oxrresponding to the mean velocity over a small region of the flowing stream. The observation range of 112mm is divided into 128 depth channels. The size of this sample volume determines the flowmeter sensitivity and accuracy. The device uses a quadrature detector to detect the direction of the moving target(hemoglobin). The main feature of the novel instrumnet is its simple hardware structure due to sequential signal processing.

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Numerical Simulation of Radio Signal Characteristics in Meteor Burst Radio Channel (유성 버스트 통신 경로의 무선 신호 특성 해석)

  • 김병철;미하일티닌
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.3
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    • pp.563-569
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    • 2004
  • The formulas taking into account the fundamental features of a meteoric radio propagation are obtained. Numerical simulation analysis has shown complex space structure of a field. Time behavior of intensity are researched taking into account nonstationary model. It is shown, this behavior essentially depends on parameters of a meteor trail, and that there is large variety of time dependencies of the signal intensity at the single scattering. In particular, at appropriate parameters of a meteor underdense trail it is possible large duration meteor bursts with which usually refer to an overdense meteor propagation.

Three Dimensional Responses of Middle Rise Steel Building under Blast Loads (폭발하중을 받는 강구조 중층 건물의 응답 및 해석)

  • Hwang, Young-Seo;Lee, Wan-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.6
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    • pp.629-636
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    • 2011
  • It has been suggested that buildings designed for strong ground motions will also have improved resistance to air blast loads. As an initial attempt to quantify this behavior, the responses of a ten story steel building, designed for the 1994 building code, with lateral resistance provided by perimeter moment frames, is considered. An analytical model of the building is developed and the magnitude and distribution of blast loads on the structure are estimated using available computer software that is based on empirical methods. To obtain the relationship between pressure, time duration, and standoff distance, these programs are used to obtain an accurate model of the air blast loading. A hemispherical surface burst for various explosive weights and standoff distances is considered for generating the air blast loading and determining the structural response. Linear and nonlinear analyses are conducted for these loadings. Air blast demands on the structure are compared to current seismic guidelines. These studies present the displacement responses, story drifts, demand/capacity ratio and inelastic demands for this structure.

Fast Acoustic Radiation Force Impulse Imaging Using Non-focused Transmission in Medical Ultrasound Imaging (초음파 의료 영상에서 비집속 송신을 이용한 고속 음향 복사력 임펄스 영상법)

  • Choi, Seung-Min;Park, Jeong-Man;Kwon, Sung-Jae;Jeong, Mok-Kun
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.3
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    • pp.151-160
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    • 2012
  • In medical ultrasound imaging, elasticity imaging helps to diagnose tumors such as cancer. This paper is concerned with the application of acoustic radiation force to soft tissue of interest to implement elasticity imaging. In order to reduce the data acquisition time, instead of relying on transmit focusing, a plane wave of burst type is transmitted to apply the acoustic radiation force simultaneously to an entire imaging region to be observed. A homogeneous phantom experiment confirms that increasing the transmit excitation duration instead of employing transmit focusing generates a high enough acoustic radiation force to obtain elasticity images. It is found, however, that a different displacement versus time characteristic is observed unlike the case of using a conventional focused acoustic radiation force. Experimental results obtained through the use of an ultrasound phantom and a bovine liver show that lesions can be correctly differentiated.

Ganoderma lucidum균 전처리를 이용한 볏짚의 상압.소다펄프화

  • 주용찬;강진하
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.34 no.4
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    • pp.51-60
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    • 2002
  • This study was carried out to develop the biochemical pulping method to enhance energy saving and decrease the capital cost through the soda pulping under atmospheric pressure (100%). Nonwood substrates, rice straw, were pretreated by white-rot fungi, Ganoderma Iucidum. It has acquired several basic data that can be applied in bio-soda pulping. The results of this study were as follow. Without any nutrients or with glucose, N and glucose+N the weight losses of rice straws inoculated by Canoderma Iucidum were 8.5~29.8%, 9.3~32% 11.8~30.1% and 11.8~24.4% respectively for 5, 10, 15, 20, 25 and 30 days incubation. The more extending incubation periods, the more increasing weight losses. The yield of untreated rice saw was 54.8% after pulping. When any nutrients was not added or glucose, N and glucose+N were added for the pretreatment, the total yields were ranged 50.6~38.5%, 48.6~34.4%, 47.2~38.4% and 49.5~42.6% respectively for 5, 10, 15, 20, 25 and 30 days incubation. The yields were gradually decreased based on extending of incubation. The physical properties of rice straw soda pulps without fungal treatment, the density, breaking length, burst index, tear index and folding endurance were 0.24 g/$\textrm{cm}^3$, 2.32 km, 0.91 kPa $m^2$/g, 56.7 mN.$m^2$/g and 35 times, respectively. After pretreatment without any nutrients or with glucose, N and glucose+N as nutrients the density was 0.27~0.30 g/$\textrm{cm}^3$, the breaking length 3.14~5.25 km, burst index 1.42~2.78 kPa.$\textrm{m}^2$/g, tear index45.8~64.5 mN.$\textrm{m}^2$/g and folding endurance 47~288 times at all incubating periods when pulping was done. The physical properties were increased with the increasing incubation periods. However, when glucose+N was added, the physical properties were shown superior results each incubating duration.

The Design of th GRACE-LB Algorithm for Congestion Control in Broadband ISDN ATM Network (광대역 ISDN ATM 네트워크의 과잉 밀집 제어를 위한 GRACE-LB 알고리즘의 설계)

  • 곽귀일;송주석
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.5
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    • pp.708-720
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    • 1993
  • The new preventive control mechanisms for traffic management in BISDN/ATM networks can be divided into Connection Admission Control(CAC), Usage Parameter Control (UPC), and Priority Control. Of these mechanism, Usage Parameter Control continuously monitors the parameters admitted in the network's entry point to guarantee quality of service of connections already admitted. Upon detecting traffic that violates the negotiated parameter, it takes the necessary control measures to prevent congestion. Among these traffic control methods, this paper focuses on the Usage Parameter Control method, and proposes and designs GRACE-LB(Guaranteed Rate Acceptance & Control Element-using Leaky Bucket) which improves upon existing UPC models. GRACE-LB modifies the previous LB model by eliminating the cell buffer, dividing the token Pool into two pools, Long-term pool, Short-term pool, and changing the long-term token generating form using 'Cycle Token' into the same bursty form as the traffic source. Through this, GRACE-LB achieves effective control of the Average Bit Rate(ABR) and burst duration of bursty multimedia traffic which previous LB models found difficult to control. Also, since GRACE-LB can e implemented using only simple operations and there are no cell buffers in it, it has the merit of being easily installed at any place.

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Analysis on Damage of Porcelain Insulators Using AE Technique (AE기법을 이용한 자기애자의 손상 분석)

  • Choi, In-Hyuk;Shin, Koo-Yong;Lim, Yun-seog;Koo, Ja-Bin;Son, Ju-Am;Lim, Dae-Yeon;Oh, Tae-Keun;Yoon, Young-Geun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.3
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    • pp.231-238
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    • 2020
  • This paper investigates the soundness of porcelain insulators associated with the acoustic emission (AE) technique. The AE technique is a popular non-destructive method that measures and analyzes the burst energy that occurs mainly when a crack occurs in a high-frequency region. Typical AE methods require continuous monitoring with frequent sensor calibration. However, in this study, the AE technique excites a porcelain insulator using only an impact hammer, and it applies a high-pass filter to the signal frequency range measured only in the AE sensor by comparing the AE and the acceleration sensors. Next, the extracted time-domain signal is analyzed for the damage assessment. In normal signals, the duration is about 2ms, the area of the envelope is about 1,000, and the number of counts is about 20. In the damage signal, the duration exceeds 5ms, the area of the envelope is about 2,000, and the number of counts exceeds 40. In addition, various characteristics in the time and frequency domain for normal and damage cases are analyzed using the short-time Fourier transform (STFT). Based on the results of the STFT analysis, the maximum energy of a normal specimen is less than 0.02, while in the case of the damage specimen, it exceeds 0.02. The extracted high-frequency components can present dynamic behavior of crack regions and eigenmodes of the isolated insulator parts, but the presence, size, and distribution of cracks can be predicted indirectly. In this regard, the characteristics of the surface crack region were derived in this study.

The Analysis of Neuro-Physiological Outcome of Patients with Status Epilepticus in an Intensive Care Unit (집중치료실에서 치료한 중첩성 경련 환자의 신경생리학적 결과 분석)

  • Kim, Dae-Sik;Kim, Cheon-Sik
    • Korean Journal of Clinical Laboratory Science
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    • v.37 no.2
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    • pp.96-101
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    • 2005
  • Status epilepticus is a medical emergency, so that rapid and vigorous treatment is required to prevent neuronal damage and systemic complication. Status epilepticus is generally defined as a continuous or intermittent seizure or an unconscious condition after the onset of seizure, lasting for 30 minutes or more. We report here the outcome of status epilepticus. We retrospectively reviewed medical record of 15 patients who were diagnosed with status epilepticus at the Asan Medical Center from January 2003 to February 2004. This outcome was evaluated considering various factors such as age of patients, history of seizures, neurologic impairment, etiology, mortality, return to baseline and initial electroencephalogram (EEG) findings. The range of age was between 1 to 79 years old and the longest duration of treatment was 118 days. Most patients were treated by using pentobarbital, midazolam, phenobarbital and other antiepileptic drugs. The overall mortality was 5 (33%) out of 15 patients. The mortality was related to etiology, underlying other medical conditions and initial EEG findings. 5 (55%) out of the 9 patients with acute etiology, 5 (71%) out of the 7 patients with a multifocal or burst-suppression EEG activity, and 3 (60%) out of the 5 patients with other medical disease were related to mortality. This data demonstrate high mortality due to status epilepticus. Mortality is related to etiology, other medical conditions and abnormalities on the initial EEG.

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An Acoustic and Aerodynamic Study of Consonants in Cheju

  • Cho, Tae-Hong;Jun, Sun-Ah;Ladefoged, Peter
    • Speech Sciences
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    • v.7 no.1
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    • pp.109-141
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    • 2000
  • Acoustic and aerodynamic characteristics of Cheju consonants were examined with the focus on the well-known three-way distinction among stops (i.e., lenis, fortis, aspirated) and the two-way distinction between sand s*. Acoustic parameters examined for the stops included VOT, relative stop burst energy, Fo at the vowel onset, H1-H2, and H1-F2 at the vowel onset. For the fricatives s and s*, acoustic parameters were fricative duration, Fo, centroid of the fricative noise, RMS energy of the frication, H1-H2 and Hl-F2 at the onset of the following vowel. In investigating aerodynamics, intraoral pressure and oral flow were included for the bilabial stops. Results indicate that, although Cheju and Korean are not mutually intelligible, acoustic and aerodynamic properties of Cheju consonants are very similar in every respect to those of the standard Korean. Among other findings there are three crucial points worth recapitulating. First, stops are systematically differentiated by the voice quality of the following vowel. Second, stops are also differentiated by aerodynamic mechanisms. The aspirated and fortis stops are similar in supralaryngeal articulation, but employ a different relation between intraoral pressure and flow. Finally, our study suggests that the fricative s is better categorized as 'lenis' than as 'aspirated' in terms of its phonetic realization.

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