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Applying an Auxiliary Filter in the Adaptive Echo Canceller for Performance Improvement of Double-Talk Detection (음향반향제거기에서 보조필터를 이용한 동시통화 검출 성능 개선)

  • Kim Si Ho;Kwon Hong Seok;Bae Keun Sung
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.249-252
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    • 2002
  • 본 논문에서는 음향반향제거기에서 상관계수를 이용하여 동시통화 구간을 검출하는 방법에서 검출 오류로 인해 발생되는 문제점에 대해서 다룬다. 상관계수(correlation coefficient)를 이용한 DT 검출 방법에서 동시통화 구간과 반향경로의 변화를 명확하게 구분 짓는 문턱값 설정이 어렵기 때문에 때때로 검출 오류가 발생한다. 즉, 동시통화 중간에 반향경로가 변함으로써 동시통화 구간의 끝점 검출에 실패하거나 반항경로 변화를 DT로 잘못 인식하는 경우가 발생하는데, 이럴 경우 더 이상 적응필터의 계수를 갱신을 할 수 없는 상태에 빠지기도 한다. 본 논문에서는 반향제거기에 보조필터를 사용하여 이러한 문제점을 해결하고자 한다. 이는 보조필터가 기준입력신호(reference signal)를 이용하여 변화된 반향신호 성분은 추정할 수 있지만 근단화자 신호는 추정할 수 없다는 점을 이용한다 실험을 통해 제안한 알고리즘이 검출 오류로 인해 발생되는 문제를 효율적으로 해결할 수 있음을 확인하였다.

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Ignition of Fuel-rich Propellant Coated with Ignition Support Material in the Ramjet Combustor Condition (램젯 연소실 조건에서 점화보조제가 도포된 Fuel-rich 추진제의 점화)

  • Jung, Woosuk;Baek, Seungkwan;Kim, Youngil;Kwon, Taesoo;Park, Juhyun;Kwon, Sejin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.4
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    • pp.79-88
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    • 2017
  • Ignition test of the fuel-rich propellant coated with ignition support material in the ramjet combustor condition was conducted. Ignition delay and flame holding was measured. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Al particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. Ethanol blended $H_2O_2$ gas generator control the temperature, pressure, $O_2$ concentration in the oxidizer gas in the air. Gas is supplied with mass flux of $200kg/m^2s$. Through the test ignition support operated well and ignition delay of 0.6 second and the Flame was sustained.

폐섬유자원의 발효공학적 이용에 관한 연구(제8보) 섬유소자화세균의 악합장양

  • 윤한대;성낙계
    • Proceedings of the Korean Society for Applied Microbiology Conference
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    • 1977.10a
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    • pp.196.1-196
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    • 1977
  • 전보에서 보고한 바 있는 Cellulomonas속 한 균주와 분리선정한 보조균을 CM-Cellulose로 기회로 하여 혼합배양하였을 때 각각 단독으로 배양하였을 때 보다 균주증식이 아주 양호하였음을 알았으며 분리 보조균에 대한 균학적 성질을 조사한 결과 Sporocytophaga속의 성질과 거의 일치하였다.(중략)

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인계 난연제를 사용한 난연 EPDM 폼에서 팽창흑연 첨가효과 분석

  • Jang, Yu-Ri;Lee, Deok-Hui;Gang, Gyeong-Min;Lee, Dong-Yeop
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2013.11a
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    • pp.221-222
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    • 2013
  • 다양한 첨가제가 들어가는 고분자 화합물(compound)의 제조에 있어 난연 발포 보조제인 팽창흑연(Expandable Graphite, EGP)은 흡유가가 낮기 때문에 비교적 많은 양을 첨가해도 혼합(Mixing)이 잘 되는 것으로 알려져 있다. 본 논문에서는 대표적인 인계 난연제 APP(Ammonium Polyphosphate)를 사용한 난연 EPDM(Ethylene Propylene Diene Monomer) 폼에 팽창흑연 첨가량을 증가시키면서 산소 지수와 발열량을 통해 난연 성능의 변화를 분석하였다. 산소지수는 ISO 4589-2 상온 산소지수 방법을, 발열량 평가는 ISO 5660-1 콘 칼로리미터를 활용하였다.

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Effect of Cosurfactant on Intermediate Phase Formation in Systems Containing Alkyl Ethoxylate Nonionic Surfactant, Water and Lubricant (Alkyl Ethoxylate 비이온 계면활성제, 물과 윤활유를 포함한 시스템에서 보조계면활성제가 중간상 생성에 미치는 영향에 관한 연구)

  • Lim, Jong Choo
    • Applied Chemistry for Engineering
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    • v.16 no.6
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    • pp.778-784
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    • 2005
  • It has been found that the addition of cosurfactant is necessary in order to expand three phase region containing middle phase microemulsion in ternary systems containing alkyl ethoxylate (AEO) nonionic surfactant, commercial lubricant and water. Phase behavior in the surfactant systems with addition of cosurfactant over a temperature range of 30 to $60^{\circ}C$ showed different trends depending on surfactant, temperature and chain length of alcohol added. For the $C_{12}E_4$ system, addition of n-pentanol and n-hexanol both produced a three phase region over a wide range of temperatures but the middle-phase formed was found to be a $L_3$ or D' phase which would not facilitate solubilization of high molecular weight lubricants. On the other hand, for the $C_{12}E_5$ system, the middle-phase microemulsion was found to be formed with addition of a rather long-chain alcohol such as n-hexanol, n-heptanol, n-octanol, or n-nonanol. The results shown with the addition of cosurfactant was understood in connection with interfacial tension measurements and composition analysis. The inability of the hydrocarbon region of the surfactant films to incorporate the large lubricant molecules and high solubility of a hydrophobic surfactant are thought to be the chief reasons for poor solubilization with D' phase.

Utilization of Fly Ash as a Source of Mineral Fertilizers -IV. Development of Slowly Released K Fertilizer (Fly Ash 비료화(肥料化) 연구(硏究) -IV. Fly Ash를 이용(利用)한 지효성(遲效性) 가리(加里) 비료(肥料) 개발(開發))

  • Shin, Jae-Sung;Seong, Ki-Seog;Choi, Du-Hoi
    • Korean Journal of Soil Science and Fertilizer
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    • v.27 no.1
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    • pp.10-14
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    • 1994
  • The slowly released potassium fertilizer was developed by mixing fly ash with KOH, anthracite coal powder, KCI, $K_2CO_3$ and $Mg(OH)_2$ as the substances for accelerating calcination. Measuring proper ratios of raw materials, we found that the anthracite coal powder was 12 percent and $Mg(OH)_2$ was two to three percent. The optimal calcination temperature and time were proved to be $850^{\circ}C$ and 30 minutes, respectively, however, the trial product with lower temperature and shorter time in calcination had low quality. The K solubility of the product was very low compared to that of the KCl fertilizer.

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