• Title/Summary/Keyword: 쌍극자

Search Result 299, Processing Time 0.034 seconds

Negative apparent resistivity in dipole-dipole electrical surveys (쌍극자-쌍극자 전기비저항 탐사에서 나타나는 음의 겉보기 비저항)

  • Jung, Hyun-Key;Min, Dong-Joo;Lee, Hyo-Sun;Oh, Seok-Hoon;Chung, Ho-Joon
    • Geophysics and Geophysical Exploration
    • /
    • v.12 no.1
    • /
    • pp.33-40
    • /
    • 2009
  • In field surveys using the dipole-dipole electrical resistivity method, we often encounter negative apparent resistivity. The term 'negative apparent resistivity' refers to apparent resistivity values with the opposite sign to surrounding data in a pseudosection. Because these negative apparent resistivity values have been regarded as measurement errors, we have discarded the negative apparent resistivity data. Some people have even used negative apparent resistivity data in an inversion process, by taking absolute values of the data. Our field experiments lead us to believe that the main cause for negative apparent resistivity is neither measurement errors nor the influence of self potentials. Furthermore, we also believe that it is not caused by the effects of induced polarization. One possible cause for negative apparent resistivity is the subsurface geological structure. In this study, we provide some numerical examples showing that negative apparent resistivity can arise from geological structures. In numerical examples, we simulate field data using a 3D numerical modelling algorithm, and then extract 2D sections. Our numerical experiments demonstrate that the negative apparent resistivity can be caused by geological structures modelled by U-shaped and crescent-shaped conductive models. Negative apparent resistivity usually occurs when potentials increase with distance from the current electrodes. By plotting the voltage-electrode position curves, we could confirm that when the voltage curves intersect each other, negative apparent resistivity appears. These numerical examples suggest that when we observe negative apparent resistivity in field surveys, we should consider the possibility that the negative apparent resistivity has been caused by geological structure.

Gelation Behavior of Acrylonitrile Copolymer/Dimethylformamide Solution and Mechanical Properties of Films Obtained from It′s Solution (아크릴로니트릴공중합체-디메틸포름아마이드 용액의 겔화 거동 및 겔필름의 물성)

  • 오영세;한삼숙;송기원
    • Polymer(Korea)
    • /
    • v.24 no.6
    • /
    • pp.787-793
    • /
    • 2000
  • The acrylonitrile copolymer/dimethylformamide (DMF) solutions were prepared to investigate the gelation behavior and critical gel concentration (c*). Gelation is rapidly progressed with the increase of molecular weight of copolymer, but significantly delayed with supercooling temperature and comonomer contents. The c* behavior showed contrary trend against gelation behavior. In dynamic viscoelastic test, two glass-transition region were observed in film obtained from gelled solution whereas one glass-transition in film obtained from true solution. This result supports the idea that an ordered junction zone is formed by the dipole-dipole interaction of intermolecularly neighboring stereo-regular parts of atactic acrylonitrile copolymer chains due to a nucleation process in the solution.

  • PDF

Three-Dimensional Standard Curves in Induced Polarization Method (IP법(法)의 3차원(次元) 표준곡선(標準曲線))

  • Kim, Hee Joon
    • Economic and Environmental Geology
    • /
    • v.16 no.4
    • /
    • pp.269-276
    • /
    • 1983
  • This paper describes three-dimensional (3-D) standard curves for single prismatic buried bodies in induced polarization (IP) method. Dipole-dipole IP responses for the bodies are calculated by the numerical modeling technique using an integral equation solution. The pattern of IP responses for conductive targets depends on the ratio of the width of body to the depth extent. The IP response of a body of six units in strike length approximates that of a two-dimensional body. In addition, if the strike length is long enough, a layered-earth interpretation is applicable for a body much longer than four units in width. Moving an IP line away from the center of a body alon gstrike produces an effect similar to that of increasing the depth. Moving the location of body along line has little effect to the pattern of IP responses.

  • PDF

Behavior of Normalized Voltage Curves in the Resistivity Method (전기비저항 탐사에서 전위감쇠곡선의 거동특성)

  • Cho, In-Ky;Lee, Keun-Soo
    • Geophysics and Geophysical Exploration
    • /
    • v.13 no.4
    • /
    • pp.364-369
    • /
    • 2010
  • Resistivity data should be edited before the inversion because resistivity data are contaminated by a lot of noise. Generally, outlier or data violating pants-leg effect in dipole-dipole array were used to be rejected in the apparent resistivity pseudo-section. For more precise data editing, normalized voltage curves are used. In this study, we analyzed the behavior of normalized voltage curves for pole-pole, pole-dipole and dipole-dipole arrays in the presence of threedimensional inhomogeneities, and finally re-examined the validity of normalized voltage curves in the editing process of resistivity data.

Delineation of water seepage in earth-fill embankments by electrical resistivity method (전기비저항탐사에 의한 제당의 누수구간 탐지)

  • 정승환;김정호;양재만;한규언;김영웅
    • The Journal of Engineering Geology
    • /
    • v.2 no.1
    • /
    • pp.47-57
    • /
    • 1992
  • Geophysical methods applied to water seepage problem in earth-fill embankment attempt to detect and map the estimate of size and depth of the seepage path. Seepage zones generally produce lOW resistivity anomalies due to high saturation of water. Dipole-dipole resistivity surveying technique, which is actually a combined sounding-profiling procedure, was used to delineate the seepage path through this study. In this study, the finite difference methods to solve the electric potential distribution in 2 112 dimension, was adopted as the numerical scheme for the forward problem. Second order Marquart's method, one the iterative damped least square methods, was selected for the automatic inversion. The computer program was implemented in FORTRAN 77 for 1 6-bit personal computer. In this paper, we present a case history which illustrates the application of dipole-dipole resistivity method to the delineation of water flow in earth-fill structures. Also the automatic two-dimensional resistivity inversion was applied to a field data where the interpretive advantages of the program become evident.

  • PDF

Teachers' Understanding of Declination and Its Explanation Presented in the Earth Science II Textbook (편각에 대한 교사의 이해와 지구과학 II 교과서의 기술)

  • Lee, Gyuho
    • Journal of the Korean earth science society
    • /
    • v.35 no.7
    • /
    • pp.585-597
    • /
    • 2014
  • This study surveys how teachers can improve their understanding about the concept of declination only through reading the material presented as non-dipole magnetic model. This study also investigates a difference between the content of declination presented in "Earth Science II" textbook under the 2009 revised National Curriculum and that of the past one. Thirty teachers in Gyeonggi province and thirty three in the city of Seoul are surveyed; they are selected from the participants of required training that provides their first grade regular teaching certification. Findings of this study are as follows. First, the study finds that teacher participants possess several misconceptions about the declination. Their typical misconception show that a compass needle directly indicates the magnetic north pole. This type of misconception is not corrected only by a reading the material. Second, the study shows that the degree of teachers' understanding about the concept of declination improves through the reading the material of a non-dipole magnetic model. Third, the study reveals that the material of nod-dipole magnetic model is more effective with teachers than students. Finally, the study suggests that explanations including non-dipole magnetic model be revised in the current textbooks.

Adsorption Behavior of Monosubstituted-Halophenols by Amberlite XAD Resins (Amberlite XAD 수지에 대한 일치환 할로 페놀들의 흡착거동에 관한 연구)

  • Lee, Taek Hyeok;Lee, Dae Un
    • Journal of the Korean Chemical Society
    • /
    • v.34 no.3
    • /
    • pp.267-279
    • /
    • 1990
  • The adsorption mechanisms of phenols on XAD-2 and XAD-7 resins were studied by using the distribution coefficient(log Kd) measured in the optimum adsorption conditions. It was observed that the Langmuir adsorption isotherm, indicating a molecular size-dependent adsorption, was appropriate for characterizing the adsorption behaviors of phenols on XAD-2 and XAD-7 resins. The adsorption energies of phenols on XAD resins were calculated by Lennard-Jones potential equation. In the calculation of the adsorption energy, the molecular radii and dipole moments of the resins and phenols were calculated by their van der Waals volumes and Debye equation, respectively. The stacking factor (F) were determined from the radio of the equilibrium distance to the stacking distance of molecules. In order to explain the adsorption energy calculated from the stacking factor it was compared with the adsorption enthalpy for each of phenols which was experimentally determined by batch adsorption shake method. It was observed that the adsorption enthalpy of phenolate ions on the XAD resins was likely to be more seriously affected by dispersion interaction than by a dipole or a charge interaction.

  • PDF

Magnetic Interaction Effect on Activation Volume and Area of CoPt Magnetic Films (자성막 CoPt의 자기상호작용이 활성화 부피와 면적에 미치는 영향)

  • Kim, Hyeon Soo;Jeong, Soon Young;Suh, Su Jeong
    • Journal of the Korean Magnetics Society
    • /
    • v.23 no.6
    • /
    • pp.188-192
    • /
    • 2013
  • The magnetic interaction effect on the magnetic activation volume and area of electrodeposited CoPt magnetic films was investigated. The dipolar interaction was predominant interaction mechanism for all samples. And the interaction strength was increased with decreasing current density and increased with increasing sample thickness. Although the activation volumes of the samples fabricated at low current density were larger than those of the high current density samples, the sample thickness seemed to have little influence on the variation of activation volume. But it was found that the activation area was apparently affected by the magnetic interaction strength as well as the current density.