• 제목, 요약, 키워드: Decay Length

검색결과 88건 처리시간 0.029초

자장감쇠법을 이용한 $(Bi,Pb)_2Sr_2Ca_2Cu_3O_x$/Ag 초전도선재의 접합저항 측정 (Measurement of Joint Resistance of $(Bi,Pb)_2Sr_2Ca_2Cu_3O_x$/Ag Superconducting Tape by Field decay Technique)

  • 김정호;이승묵;주진호
    • Progress in Superconductivity
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    • v.14 no.1
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    • pp.1-10
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    • 2012
  • We fabricated a closed coils by using resistive-joint method and the joint resistance of the coils were estimated by field decay technique in liquid nitrogen. We used the Runge-kutta method for the numerical analysis to calculate the decay properties. The closed coil was wound by $(Bi,Pb)_2Sr_2Ca_2Cu_3O_x$/Ag tape. Both ends the tape were overlapped and soldered to each other. The current was induced in a closed coils by external magnetic flux density. Its decay characteristic was observed by means of measuring the magnetic flux density generated by induced current at the center of the closed coil with hall sensor. The joint resistance was calculated as the ratio of the inductance of the loop to the time constants. The joint resistances were evaluated as a function of critical current of loop, contact length, sweep time, and external magnetic flux density in a contact length of 7 cm. It was observed that joint resistance was dependent on contact length of a closed coil, but independent of critical current, sweep time, and external magnetic flux density. The joint resistance was measured to be higher for a standard four-probe method, compared with that for the field decay technique. This implies that noise of measurement in a standard four-probe method is larger than that of field decay technique. It was estimated that joint resistance was $8.0{\times}10^{-9}{\Omega}$ to $11.4{\times}10^{-9}{\Omega}$ for coils of contact length for 7 cm. It was found that 40Pb/60Sn solder are unsuitable for persistent mode.

A Nuclide Decay Chain Transport Model by the Method of Characteristics

  • Lee, Youn-Myoung;Kang, Chul-Hyung;Hahn, Pil-Soo;Chun, Kwan-Sik
    • Nuclear Engineering and Technology
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    • v.29 no.4
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    • pp.320-326
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    • 1997
  • The nuclide transport in the one-dimensional porous medium is considered as a first step in developing a decay chain transport in multidimensional inhomogeneous media. A method of solving conventional advection-dispersion equation with decay chain of arbitrary length by using the method of characteristics (MOC) is introduced. In specific cases where the advection are dominant rather than dispersion, the method is known to be useful : one of the most distinctive advantages in applying the model is that the MU minimizes the numerical dispersion, which is distinguished in such common numerical schemes as finite element method and finite difference method. The suggested model is considered to be effective through several illustrations for the case that decay chain of arbitrary length is involved during transport which is difficult to solve by standard numerical solutions if the medium becomes more complicated.

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가입자 통신 선로에서의 뇌격 파라미터 분석과 측정 (Analysis and Measurement of Lightning Parameters on Subscriber Telecommunication Lines)

  • 오호석;박동철
    • 한국전자파학회논문지
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    • v.18 no.11
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    • pp.1309-1317
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    • 2007
  • 본 논문은 낙뢰에 의해 전송 선로에 유기되는 유도뢰 전압을 해석하고 낙뢰 위치 및 선로 길이에 따른 유도뢰 전압의 크기, 파두장, 파미장 등에 대한 낙뢰 파라미터 변화를 분석하였다. 분석한 결과를 확인하기 위해 실제 통신 선로를 대상으로 유도뢰 전압을 측정하였다. 선로 길이가 길어짐에 따라 그리고 낙뢰 위치가 선로와 멀어짐에 따라 파두장, 파미장이 증가하는 경향을 확인하였다. 전체 선로 길이보다는 가공 선로 길이가 상대적으로 유도 전압 크기에 영향을 끼침을 확인하였다.

이차원 무한요소 형성에 관한 연구 (Study on the Formulation of Two Dimensional Infinite Elements)

  • 신용태;임장근
    • 대한기계학회논문집
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    • v.17 no.5
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    • pp.1066-1073
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    • 1993
  • Using regular finite elements and infinite elements simultaneously, elastic boundary value problems with infinite domain can be analyzed more effectively and accurately. In this paper, two dimensional infinite elements have been formulated by means of applying the derived mapping function to the coordinates and multiplying the regular displacement shape functions by a decay function. Orders(m, n) of the mapping and decay functions are found for the purpose of obtaining the convergent solutions without respect to the various decay lengthes. As a result of numerical tests for an infinite plate with a hole under internal pressure, two sets of function orders are obtained as follows. (a) n=0, m=1.5 (b) n=m=0.65

지수감쇠 기법을 이용한 반사경 손실측정 시스템의 오차특성 연구 (Study of the error chsracteristics in a mirror loss measurement system using an exqonential decay metod)

  • 조민식
    • 한국광학회지
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    • v.12 no.2
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    • pp.77-82
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    • 2001
  • 손실 200 ppm급과 30 ppm급인 두 종류의 시험 반사경을 대상으로, 지수감쇠 방법을 이용한 반사경 손실측정 시스템의 오차 특성이 조사되었다. 공진기 길이 떨림에 의한 공진기 감쇠신호의 지수함수 왜곡을 보상하기 위하여 감쇠신호 데이터 평균기법을 적용하였다. 감쇠신호 6개의 평균이 취해졌을 때 감쇠신호의 지수함수 곡선맞춤 오차개선이 뚜력시 관측되었으며 손실 200ppm급 시험 반사경의 경우 약 2.4배 손실 30ppm급 시험 반사경의 경우 약 1.3배의 반사경 손실 측정오차 개선효과를 얻을 수 있었다 시험 공진기에서의 일별(day-to-day) 반사경 손실측정 반복도 오차가 조사되었다. 손실 200ppm급 시험 반사경의 경우 약 5.0%, 30ppm급 시험 반사경의 경우 약 26.4%의 손실측정 반복도 오차가 관측되었다. 저손실 반사경 평가에서 확인된 낮은 감쇠신호 데이터 평균효과와 높은 손실측정 반복도 오차는 손실측정 시스템 자체의 측정오차 이외에 시험 반사경 표면의 불균일한 손실 공간분포와 주변 오염원 유입의 결과로 분석되었다 또한 공진기 길이 떨림의 크기와 공진기 길이 측정오차가 손실측정 시스템의 정확도에 미치는 영향을 계산을 통해 조사한 결과, 분해능 수 ppm 급 현재의 측정 시스템의 성능에 미칠수 있는 공진기 길이오차의 영향은 충분히 적은 것으로 확인되었다.

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원전 중성미자 검출을 위한 액체섬광검출용액의 감쇄거리 측정 (Measurement of the Attenuation Length of a Liquid Scintillator for the Detection of Reactor Neutrinos)

  • 박영서;김승찬;주경광
    • 새물리
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    • v.67 no.7
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    • pp.842-845
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    • 2017
  • 원전중성미자 검출은 원자로의 핵분열 과정에서 발생한 반전자 중성미자가 검출기내의 양성자와 충돌한 후, 양전자와 중성자로 변환되는 역베타붕괴 (inverse beta decay, ${\bar{\nu}}_e+p{\rightarrow}e{^+}+n$, IBD) 반응을 이용한다. 역베타붕괴에서 생성되는 양전자는 쌍소멸 하며 빛을 방출하고 중성자는 주변의 원자핵에 포획되는 과정에서 빛을 내게 되는데 각각의 신호에 일정 시간 차이를 주어서 구별할 수 있다. 원전 중성미자 표적으로 액체섬광검출용액을 사용할 수 있다. 이때 발생된 빛이 광증폭관에 잘 도달해야 여러가지 물리적 성질 측정이 가능하기 때문에 액체섬광검출용액의 감쇄거리 측정은 매우 중요하다. 본 논문은 액체섬광검출용액의 감쇄거리를 측정하기 위한 측정 장비 개발 과정 및 결과에 대해 간략히 기술하였다.

ANALYSIS OF VELOCITY STRUCTURE OF WALL JET ORIGINATING FROM CIRCULAR ORIFICES IN SHALLOW WATER

  • Kim, Dae-Geun;Seo, Il-Won
    • Water Engineering Research
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    • v.3 no.4
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    • pp.235-245
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    • 2002
  • In this study, breakwater model which has several outlet pipes to discharge water is settled in the experimental open channel and mean velocity distributions of multi wall jet are measured. The length of flow of flow establishment of wall jet is shorter than that of free jet and decay rate of jet centerline longitudinal velocity along x is linear in 0.3 $\leq$ x/$\l_q$ $\leq$ 17. The rate of vertical width and lateral width spreading of multi wall jet is respectively 0.0753, 0.157~0.190.

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Comparison of the change in quality indices during distribution period by import season in three grape cultivars

  • Kim, Sung-Joo;Noh, Soo-In;Lim, Byung-Sun;Chun, Jong-Pil
    • 농업과학연구
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    • v.46 no.1
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    • pp.45-56
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    • 2019
  • As a result of analyzing the quality of imported grapes during the 2018 season, the hardness of the grape berry was found to be 10 N or less in total. In the case of Chilean grapes, the soluble solids tended to be lower as imports and distribution periods were delayed. The berry weight was the largest at 14.4 - 14.8 g for the 'Red Globe', 7.1 - 7.4 g for the 'Thompson Seedless' and 6.0 - 7.0 g for the 'Crimson Seedless'. The 'Crimson Seedless' grapes imported from Chile, which had a high berry shatter rate, had a shorter pedicel length, pad width and brush length than that of the other 2 varieties. Regardless of the grape varieties, the weight loss during the distribution at room temperature ($25^{\circ}C$) increased rapidly as the import season was delayed. Additionally, it was found that the later the distribution seasons, a higher stem browning index was observed regardless of the variety. The 'Thompson Seedless' was revealed to be more susceptible to browning than that of the other varieties. The shrinkage of the stem and the pedicel browning progressed within a short time during shelf-life as the distribution time was delayed. The incidence of berry decay of the imported grapes tended to increase with the progression of the distribution period. In the fruits distributed on April, except for the 'Crimson Seedless', the grapes were rapidly corrupted in the second half of the distribution. The 'Red Globe' grapes completely lost marketability due to a berry decay of 26.1% and 69.9% at 9 and 12 days after shelf-life, respectively.

ACQ 약제의 목재 내 침투 및 부후 특성에 미치는 목재 조직의 영향 (Penetration of ACQ Treatment and its Effect of Degradation on Wood Tissues (Structure))

  • 이현미;이동흡;황원중
    • 목재공학
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    • v.41 no.6
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    • pp.576-582
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    • 2013
  • 구리계 보존제 처리에 대한 기초 자료를 얻기 위하여 Douglas fir 변재와 ACQ-2 보존제를 사용하여 목재 내 침투 및 부후 특성을 조사하였다. 약제의 주입이 어려운 Douglas fir 수종에 대하여 약제의 주입이 잘된 곳과 안된 곳의 시료를 채취하여 약제 이동을 방해하는 인자를 구명하고자 방사조직 높이, 방사조직 밀도, 가도관의 길이를 실체현미경, 광학현미경, 그리고 전자현미경으로 측정 및 관찰하였다. 그 결과 방사조직의 높이와 밀도 그리고 가도관길이는 약제의 주입이 용이했던 부분과 주입이 안된 부분에서 차이를 보이지 않았지만, 목재 구성 세포들의 벽공에서는 차이가 나타났음을 전자현미경을 통해 관찰할 수 있었다. 약제의 주입이 안된 곳에서는 폐색된 벽공이 많이 관찰되었다. 그리고 여러 농도의 ACQ로 처리한 목재 시편을 갈색부후균으로 부후시킨 후 광학 현미경으로 부후 특성을 관찰하였다. 그 결과 무처리 시편의 가도관, 방사조직, 수지구 등의 조직이 부후되어 파괴된 것을 볼 수 있었으며, 약제 처리 농도가 낮으면 부후가 진행되므로 일정 농도 이상으로 처리해야함을 알 수 있었다.

지수창함수를 사용한 임팩트햄머 실험에서 주파수응답함수의 왜곡과 개선책 (FRF Distortion Caused by Exponential Window Function on Impact Hammer Testing and Its Solution)

  • 안세진;정의봉
    • 한국소음진동공학회논문집
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    • v.13 no.5
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    • pp.334-340
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    • 2003
  • Exponential window function Is widely used In impact hammer testing to reduce leakage error as well as to get a good S/N ratio. The larger its decaying rate is, the more effectively the leakage errors are reduced. But if the decay rate of the exponential window is too large, the FRF is distorted. And the modal parameters of the system can not be exactly identified by modal analysis technique. Therefore, it is a difficult problem to determine proper decay rate in impact hammer testing. In this paper, amount of the FRF distortion caused by exponential window is theoretically uncovered. A new circle fitting method is also proposed so that the modal parameters are directly extracted from impulse response spectrum distorted by the exponential-windowed impulse response data. The results by the conventional and proposed circle fitting method are compared through a numerical example.