• Title, Summary, Keyword: Decay Length

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

  • Kim, Jung-Ho;Lee, Seung-Muk;Joo, Jin-Ho
    • 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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Analysis and Measurement of Lightning Parameters on Subscriber Telecommunication Lines (가입자 통신 선로에서의 뇌격 파라미터 분석과 측정)

  • Oh, Ho-Seok;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.11
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    • pp.1309-1317
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    • 2007
  • In this paper, the Induced voltage on transmission line by lightning was calculated using FDTD method and the lightning parameters such as peak voltage, rise time, and decay time for the lightning location and line length were analyzed. To verify the results, lightning induced voltage was measured in the field using real telecommunication line. Results from the collected data were compared with the calculated results. It was found that the rise time and the decay time were increased as the line length and the distance between the line and lightning location were increased. Also, the peak voltage was affected more by the overhead line length than by the total line length, while the rise time and the decay time were more affected by the total line length.

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

  • 신용태;임장근
    • Transactions of the Korean Society of Mechanical Engineers
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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

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

  • 조민식
    • Korean Journal of Optics and Photonics
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    • v.12 no.2
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    • pp.77-82
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    • 2001
  • Error characteristics of a mirror loss measurement system using an exponential decay method were studied, with the two samples having about 200-ppm-loss and 30-ppm-loss, respectively. In order to minimize the decay signal deviation from an exponential curve due to cavity length fluctuation, a data average method was tried. The data average method significantly improved the exponential curve fitting error of the decay signal, so that for a 6 decay signal data average the loss measurement error was reduced by about 2.4 times for the 200-ppm-loss mirror and 1.3 times for the 30-ppm-loss mirror compared with a single shot measurement. Day-to-day mirror loss repeatability error for the two samples was investigated. The repeatability error was measured to be about 5% for the 200-ppm-loss mirror and about 26.4% for the 30-ppm-loss mirror. Low decay signal average effect and high repeatability error in the low loss mirror measurement were explained with non-uniform spatial loss distribution of the sample and contamination from the environment, in addition to the error sources of the mirror loss measurement system itself. The influence of cavity length fluctuation and cavity length measurement error on the mirror loss measurement system performance was theoretically calculated. It confirmed that the requirement for the cavity length parameters was not so strict in the mirror loss measurement system of several ppm resolution. ution.

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

  • Park, Young Seo;Kim, Seung Chan;Joo, Kyung Kwang
    • New Physics: Sae Mulli
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    • v.67 no.7
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    • pp.842-845
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    • 2017
  • The antielectron neutrino is emitted during fission in a reactor. Through an inverse beta-decay reaction (${\bar{\nu}}_e+p{\rightarrow}e{^+}+n$, IBD), the positron and the neutron generated in the liquid scintillator will be detected by using the time difference between the prompt signal and the delayed signal. During this process, light will travel a certain distance to reach the photomultiplier tube, so measurements of the optical and the physical properties of the liquid scintillator are very important. For that reason, a precise measurement of the attenuation length in a liquid scintillator is needed. This paper briefly describes a device for measuring the attenuation length in a liquid scintillator and presents the results of those measurements.

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
    • Korean Journal of Agricultural Science
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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.

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

  • Lee, Hyun-Mi;Lee, Dong-Heub;Hwang, Won-Joung
    • Journal of the Korean Wood Science and Technology
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    • v.41 no.6
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    • pp.576-582
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    • 2013
  • To obtain the basic information on wood preservative process using copper, the penetration ACQ-2 preservative agent into Douglas fir wood and its degradational characteristics were investigated. Douglas fir is known to be difficult for preservative agent injection. To find the hindrance factor of the preservatives movement, the ray height, ray density, and length of tracheid were measured and observed by a stereoscopic microscope and scanning electron microscope. The results were compared in the well-penetrated parts of preservatives and insufficient parts. There were no significant differences in height, length, and density between both parts, except for the pits of the wood elements observed in SEM micrograph. More declosed pits were found in the well-penetrated parts of preservatives. Decay characteristics of wood specimen treated with various ACQ concentrations by brown-rot fungi was observed by an optical microscope. The decayed properties of tracheid, rays, and resin canals was found in the non-treated wood specimens and it was also found that some extent of preservatives concentration is necessary to protect the decay.

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

  • 안세진;정의봉
    • Transactions of the Korean Society for Noise and Vibration Engineering
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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.