• 제목/요약/키워드: Burst Duration

검색결과 57건 처리시간 0.037초

Collision-Free Arbitration Protocol for Active RFID Systems

  • Wang, Honggang;Pei, Changxing;Su, Bo
    • Journal of Communications and Networks
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    • 제14권1호
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    • pp.34-39
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    • 2012
  • Collisions between tags greatly reduce the identification speed in radio frequency identification (RFID) systems and increase communication overhead. In particular for an active RFID system, tags are powered by small batteries, and a large number of re-transmissions caused by collisions can deteriorate and exhaust the tag energy which may result in missing tags. An efficient collision-free arbitration protocol for active RFID systems is proposed in this paper. In this protocol, a new mechanism involving collision detection, collision avoidance, and fast tag access is introduced. Specifically, the pulse burst duration and busy-tone-detection delay are introduced between the preamble and data portion of a tag-to-reader (T-R) frame. The reader identifies tag collision by detecting pulses and transmits a busy tone to avoid unnecessary transmission when collision occurs. A polling process is then designed to quickly access the collided tags. It is shown that the use of the proposed protocol results in a system throughput of 0.612, which is an obvious improvement when compared to the framed-slotted ALOHA (FSA) arbitration protocol for ISO/IEC 18000-7 standard. Furthermore, the proposed protocol greatly reduces communication overhead, which leads to energy conservation.

CLASSIFICATION OF THE INTERPLANETARY SHOCKS BY SHOCK DRIVERS

  • OH SU YEON;YI YU;NAH JA-KYUNG;CHO KYUNG-SEOK
    • 천문학회지
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    • 제35권3호
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    • pp.151-157
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    • 2002
  • From the data of solar wind observation by ACE spacecraft orbiting the Earth-Sun Lagrangian point, we selected 48 forward interplanetary shocks(IPSs) occurred in 2000, maximum solar activity period. Examining the profiles of solar wind parameters, the IPSs are classified by their shock drivers. The significant shock drivers are the interplanetary coronal mass ejection(ICME) and the high speed stream(HSS). The IPSs driven by the ICMEs are classified into shocks driven by magnetic clouds and by ejectas based on the existence of magnetic flux rope structure and magnetic field strength. Some IPSs could be formed as the blast wave by the smaller energy and shorter duration of shock drivers such as type II radio burst. Out of selected 48 forward IPSs, $56.2\%$ of the IPSs are driven by ICME, $16.7\%$ by HSS, and $16.7\%$ of the shocks are classified into blast-wave type shocks. However, the shock drivers of remaining $10\%$ of the IPSs are unidentified. The classification of the IPSs by their driver is a first step toward investigating the critical magnitudes of the IPS drivers commencing the magnetic storms in each class.

집중치료실에서 지속적 뇌파검사의 뇌파 패턴 분석 (Analysis of the Continuous Monitored Electroencephalogram Patterns in Intensive Care Unit)

  • 김천식
    • 대한임상검사과학회지
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    • 제49권3호
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    • pp.294-299
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    • 2017
  • 이 연구의 목적은 중첩성 뇌전증을 발견하고, 처음 기록된 30분 뇌파 패턴을 통하여 경련 가능성을 알아보고자 한다. 국제표준 10~20법을 통하여 전극을 부착하였다. 2014년 1월부터 2015년 12월까지 중환자실에 입원한 경련 의심 환자를 대상으로 하였다. 뇌파의 패턴은 주기적 방전파, 전반적 주기적 방전파, 버스트 억제파, 초점 뇌전증파, 비대칭 배경파, 전반적 서파, 삼상성 형태의 일반화 된 주기적 방전파 등 7 가지 범주로 분류하였다. 원인별 분류는 5가지 범주로 구분하였다. 전체 128명 중 평균 나이는 $56.9{\pm}17.5$였고, 남:여 비율은 74:54명이였다. 평균 뇌파검사 기간은 $5.5{\pm}5.1$일 이었고 최장 33일 이였다. 주기적 방전파(N=7), 전반적 주기적 방전파(N=10), 버스트 억제파(N=6), 초점 뇌전증파(N=19), 비대칭 배경파(N=24), 전반적 서파(N=51), 3상 형태의 일반화 된 주기적 방전파(N=11)이었다. 중첩성 뇌전증 환자의 원인은 원발성 증상성(N=4), 급성원발성 증상성(N=9), 급성 증상성(N=6), 진행성 뇌병증(N=2), 열성경련(N=1)이었다. 지속적 뇌파모니터링 검사는 중첩성 뇌전증을 발견하는데 유용한 검사이고, 뇌파 패턴을 통하여 경련 발생 유무를 확인할 수 있었다.

Bio-Soda Pulping of Rice Straw with Pleurotus cornucopiae under Atmospheric Pressure

  • Ju, Yong-Chan;Kang, Jin-Ha
    • 펄프종이기술
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    • 제35권5호
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    • pp.62-71
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    • 2003
  • This study was carried out to develop the bio-chemical pulping method to enhance the energy saving and decrease the capital cost through the soda pulping under atmospheric pressure ($100^{\circ}C$). Nonwood substrates, rice straw, were pretreated by white-rot fungi, Pleurotus cornucopiae. Several basic pieces of data that can be applied in soda pulping were acquired. The results of this study were as follows. Under the conditions without any nutrients or with glucose, N and glucose + N, the weight losses of rice straws inoculated by Pleurotus cornucopiae were 12.1∼32.6 %, 12.0∼26.3 %, 13.0∼25.4 % and 15.3∼24.7 % for 5, 10, 15, 20, 25 and 30 days incubation periods respectively. The more the fungal incubation was extended, the more the weight losses were gained. The yield of untreated rice straw 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 to 57.3∼42.9 %, 51.0∼43.3 %, 51.7∼43.9 % and 52.1∼46.1 % for 5 different incubation periods respectively. The yields were gradually decreased based on the extending of the incubation periods. The physical properties of the rice straw soda pulp without fungal treatment, the density, breaking length, burst index, tear index and folding endurance were 0.24g/㎤, 2.32 Km, 0.91 kPaㆍ$m^2$/g, 46.7 mNㆍ$m^2$/g and 21 times, respectively. In the case of pretreatment without any nutrients or with glucose, N and glucose + N as nutrients, the density was 0.24g/㎤, the breaking length was 3.30∼6.46 Km, the burst index was 1.36∼3.01 kPaㆍ$m^2$/g, the tear index was 33.0∼57.0 mNㆍ$m^2$/g and the folding endurance was 14∼381 times at most incubating periods, when pulping was done. The physical properties were increased as the incubation duration was extended. Especially, when N and glucose + N were added, the physical properties showed superior results during each incubation period.

재결정 PLGA와 단량체를 이용한 5-FU/PLGA 웨이퍼의 방출거동 (Release Behavior of 5-FU from 5-FU/PLGA Wafer using Recrystallized PLGA and Monomer)

  • 박정수;최명규;김윤태;이준희;모종현;강길선;이종문;신형식;이해방
    • Korean Chemical Engineering Research
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    • 제46권2호
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    • pp.205-210
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    • 2008
  • PLGA는 생분해성 고분자이며 생체적합성을 갖는 고분자로서 약물전달을 위한 연구에 많이 이용되고 있는 고분자이다. 그러나 PLGA를 약물전달에 이용할 때 약물의 급격한 초기방출 이후에 일정기간동안 약물이 방출되지 않는 지연시간이 존재하게 된다. 이러한 문제를 해결하기 위하여 PLGA 웨이퍼에 단량체를 첨가하여 제조하였다. 또한 PLGA를 재결정하여 약물의 급격한 방출 현상을 억제하도록 하였다. SEM을 이용하여 재결정된 PLGA의 형태학적 차이를 관찰하였으며 생체외 약물 방출거동은 HPLC를 이용하여 측정하였다. PLGA의 분해과정에서 단량체의 영향을 알아보기 위하여 GPC를 이용하여 분자량 변화를 측정하였다. 본 연구를 통하여 PLGA의 벌크분해에 기인한 지연시간을 없앨 수 있었으며 약물의 방출 기간을 3일까지 앞당길 수 있었다.

전자기형 리타더의 전력회수장치 및 전압제어 (Electromagnetic Retarder's Power Recovery Device and Voltage Control)

  • 정성철;윤인식;고종선
    • 전력전자학회논문지
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    • 제21권5호
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    • pp.396-403
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    • 2016
  • Usually, large-sized buses and trucks have a very high load. In addition, frequent braking during downhill or long-distance driving, causes the conventional method using the brake friction to have a problem in safety because of brake fade and brake burst phenomenon. Auxiliary brakes dividing the braking load is essential. Hence, environment-friendly auxiliary brakes, such as contactless brake rather than the engine auxiliary brake system are needed. A study aimed at improving the energy efficiency by recharging electric energy with changing mechanical to electrical energy that occurs when braking is actively in progress. In this paper, the voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, the resonant L-C circuit is configured in the retarder. The voltage generated in the retarder is simply modeled as a transformer. However, retarder voltage control in this paper is simulated by modeling the induction generator because this induction generator modeling is more practical than transformer modeling. The changes in the voltage of the resonance circuit, which depends on the switch pulse duration of the control device, were analyzed. A PI controller algorithm to control this voltage is proposed. The feasibility of modeling retarder and voltage controller are shown by using MATLAB Simulink in this paper.

Calcium Influx is Responsible for Afterdepolarizations in Rat Hippocampal Dentate Granule Cells

  • Park, Won-Sun;Lee, Suk-Ho
    • The Korean Journal of Physiology and Pharmacology
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    • 제6권3호
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    • pp.143-147
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    • 2002
  • Granule cells in dentate gyrus of hippocampus relay information from entorhinal cortex via perforant fiber to pyramidal cells in CA3 region. Their electrical activities are known to be closely associated with seizure activity as well as memory acquisition. Since action potential is a stereotypic phenomena which is based on all-or-none principle of $Na^+$ current, the neuronal firing pattern is mostly dependent on afterpotentials which follows the stereotypic $Na^+$ spike. Granule cells in dentate gyrus show afterdepolarization (ADP), while interneurons in dentate gyrus have afterhyperpolarizaton. In the present study, we investigated the ionic mechanism of afterdepolarization in hippocampal dentate granule cell. Action potential of dentate granule cells showed afterdepolarization, which was characterized by a sharp notch followed by a depolarizing hump starting at about $-49.04{\pm}1.69\;mV\;(n=43,\;mean{\pm}SD)$ and lasting $3{\sim}7$ ms. Increase of extracellular $Ca^{2+}$ from 2 mM to 10 mM significantly enhanced the ADP both in amplitude and in duration. A $K^+$ channel blocker, 4-aminopyridine (4-AP, 2 mM), enhanced the ADP and often induced burst firings. These effects of 10 mM $Ca^{2+}$ and 4-AP were additive. On the contrary, the ADP was significantly suppressed by removal of external $Ca^{2+},$ even in the presence of 4-AP (2 mM). A $Na^+$ channel blocker, TTX (100 nM), did not affect the ADP. From these results, it is concluded that the extracellular $Ca^{2+}$ influx contributes to the generation of ADP in granule cells.

Activation of ATP-sensitive Potassium Channels by the Predominant Metabolite of Isoflurane in Rabbit Ventricular Myocytes

  • Han, Jin;Kim, Na-Ri;Kim, Eui-Yong;Kim, Sung-Ju;Cho, Kang-Hee
    • The Korean Journal of Physiology and Pharmacology
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    • 제5권2호
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    • pp.165-175
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    • 2001
  • Background: Recent in vivo experimental evidence suggests that isoflurane-induced cardioprotection may involve $K_{ATP}$ channel activation. However, it was demonstrated that isoflurane inhibited $K_{ATP}$ channel activities in the inside-out patch mode. To explain this discrepancy, the present investigation tested the hypothesis that a metabolite of isoflurane, trifluoroacetic acid (TFA), contributes to isoflurnae-induced cardioprotection via $K_{ATP}$ channel activation during myocardial ischemia and reperfusion. Methods: Single ventricular myocytes were isolated from rabbit hearts by an enzymatic dissociation procedure. Patch-clamp techniques were used to record single-channel currents. $K_{ATP}$ channel activities were assessed before and after the application of TFA with the inside-out patch mode. Results: TFA enhanced channel activity in a concentration-dependent fashion. The concentration of TFA for half-maximal activation and the Hill coefficient were 0.03 mM and 1.2, respectively. TFA did not affect the single channel conductance of $K_{ATP}$ channels. Analysis of open and closed time distributions showed that TFA increased burst duration and decreased the interburst interval without changes in open and closed time distributions shorter than 5 ms. TFA diminished ATP sensitivity of $K_{ATP}$ channels in a concentration-response relationship for ATP. Conclusions: TFA, a metabolite of isoflurane, enhanced $K_{ATP}$ channel activity in a concentration-dependent fashion. These results imply that TFA could mediate isoflurane-induced cardioprotection via $K_{ATP}$ channel activation during myocardial ischemia and reperfusion.

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CME and radio characteristics of making large solar proton events

  • 황정아;조경석;봉수찬;김수진;박영득
    • 천문학회보
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    • 제35권1호
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    • pp.33.2-33.2
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    • 2010
  • We have investigated a relationship among the solar proton events (SPEs), coronal mass ejections (CMEs) and solar flares during the solar cycle 23 (1997-2006). Using 63 SPE dataset, we found that SPE rise time, duration time, and decrease times depend on CME speed and SPE peak intensity depends on the CME earthward direction parameter as well as CME speed and x-ray flare intensity. While inspecting the relation between SPE peak intensity and the CME earthward direction parameter, we found that there are two groups: first group consists of large 6 SPEs (> 10,000 pfu at >10 MeV proton channel of GOES satellite) and shows a very good correlation (cc=0.65) between SPE peak intensity and CME earthward direction parameter. The second group has a relatively weak SPE peak intensity and shows poor correlation between SPE peak intensity and the CME earthward direction parameter (cc=0.01). By investigating characteristics of 6 SPEs in the first group, we found that there are special common conditions of the extremely large proton events (group 1); (1) all the SPEs are associated with very fast halo CME (>1400km/s), (2) they are almost located at disk region, (3) they also accompany large flare (>M7), (4) all they are preceded by another wide CMEs, and (5) they all show helmet streamer nearby the main CME. In this presentation, we will give details of the energy spectra of the 6 SPE events from the ERNE/HED aboard the Solar and Heliospheric Observatory (SOHO), and onset time comparison among the SPE, flare, type II burst, and CME.

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한국어 파열음 인식을 위한 피쳐 셉 입력 인공 신경망 모델에 관한 연구 (A STUDY ON THE IMPLEMENTATION OF ARTIFICIAL NEURAL NET MODELS WITH FEATURE SET INPUT FOR RECOGNITION OF KOREAN PLOSIVE CONSONANTS)

  • 김기석;김인범;황희융
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1990년도 하계학술대회 논문집
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    • pp.535-538
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    • 1990
  • The main problem in speech recognition is the enormous variability in acoustic signals due to complex but predictable contextual effects. Especially in plosive consonants it is very difficult to find invariant cue due to various contextual effects, but humans use these contextual effects as helpful information in plosive consonant recognition. In this paper we experimented on three artificial neural net models for the recognition of plosive consonants. Neural Net Model I used "Multi-layer Perceptron ". Model II used a variation of the "Self-organizing Feature Map Model". And Model III used "Interactive and Competitive Model" to experiment contextual effects. The recognition experiment was performed on 9 Korean plosive consonants. We used VCV speech chains for the experiment on contextual effects. The speech chain consists of Korean plosive consonants /g, d, b, K, T, P, k, t, p/ (/ㄱ, ㄷ, ㅂ, ㄲ, ㄸ, ㅃ, ㅋ, ㅌ, ㅍ/) and eight Korean monothongs. The inputs to Neural Net Models were several temporal cues - duration of the silence, transition and vot -, and the extent of the VC formant transitions to the presence of voicing energy during closure, burst intensity, presence of asperation, amount of low frequency energy present at voicing onset, and CV formant transition extent from the acoustic signals. Model I showed about 55 - 67 %, Model II showed about 60%, and Model III showed about 67% recognition rate.

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