• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.132-135
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• 2002

MI(Magneto-Impedance) sensor which is made by thin films has significantly high detecting sensitivity in weak magnetic field. It also has a merit to be able to build in the low power system. Its structure is simple, which makes it easier to prepare a miniature. In this study, its magnetic permeability and anisotropy field($H_{k}$) as a function of a thickness of sputtered amorphous CoZrNb films with zero-magnetostriction and soft magnetic property are investigated. In order to make a uniaxial anisotropy, film was subjected to the post annealing in a static magnetic field with 1KOe intensity at 250, 300, and $320^{\circ}C$ respectively for 2 hours. Magnetic properties of film are measured by using a MH loop tracer. Its magnetic permeability of a film is measured over the frequency range 1 MHz to 750MHz. And, it was examined on the permeability and impedance to design the MI sensor which acts at 50MHz by thickening a CoZrNb film relatively, and fabricated the MI sensor which acts at the 50MHz.

• Journal of Powder Materials
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• v.23 no.2
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• pp.132-135
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• 2016

This study investigates the influence of sintering temperature on the magnetic properties and frequency dispersion of the complex permeability of Ni-Zn-Cu ferrites used for magnetic shielding in near-field communication (NFC) systems. Sintered specimens of $(Ni_{0.7}Zn_{0.3})_{0.96}Cu_{0.04}Fe_2O_4$ are prepared by conventional ceramic processing. The complex permeability is measured by an RF impedance analyzer in the range of 1 MHz to 1.8 GHz. The real and imaginary parts of the complex permeability depend sensitively on the sintering temperature, which is closely related to the microstructure, including grain size and pore distribution. In particular, internal pores within grains produced by rapid grain growth decrease the permeability and increase the magnetic loss at the operating frequency of NFC (13.56 MHz). At the optimized sintering temperature ($1225-1250^{\circ}C$), the highest permeability and lowest magnetic loss can be obtained.

• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.1 s.22
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• pp.29-37
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• 2005

The design and development if Resonant-type Magnetometer(RM) using isotropic magnetic with high permeability is described in this paper. At first, the relationship between the inductance L if the coil winding on a magnetic material and the permeability u(H) appearing in the magnetic material with isotropic and high permeability is defined as a background theory. Then the circuit if RM, which is to obtain the values if L as the change qf frequency is implemented using simple Schmitt Trigger Circuit Through the swinging tests, which is to evaluate the measurement ability if RM, the measurement possibility for the component of earth field was confined.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.671-680
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• 2003

The accuracy of inflow into tunnel estimates depends largely on how well permeability is characterized. But, the average of the packer test results will always underestimate the upper end of the permeability range, and therefore underestimate the inflow. Taking an average of the test results always underestimates inflow because the average permeability does not really exist. The distribution of packer-test data may not accurately reflect permeability, however, due to the limits of the test method and the luck of the field investigation. These discrepancies may be overcome by using Raymer(2001)'s log-normal plots and Heuer(1995)'s histograms of the data to develop a permeability model that will be used in lieu of the data to calculate inflow. Furthermore, the influence on the inflow is examined by the geological characteristics based upon the hundred times of packer test OO tunnel project.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.68-70
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• 2002

Prediction of 3-D permeability tensor for multi-axial preform is critical to model and design the manufacturing process of composites by considering resin flow through the multi-axial fiber structure. In this study, the in-plane and transverse permeabilities for braided preform are predicted numerically. The flow analyses are calculated by using 3-D CVFEM(control volume finite element method) for macro-unit cells. To avoid checker-board pressure field and improve the efficiency of numerical computation, a new interpolation function for velocity is proposed on the basis of analytic solutions. Permeability of a braided preform is measured through unidirectional flow experiment and compared with the permeability calculated numerically. Unlike other studies, the current study is based on more realistic unit cell and prediction of permeability is improved.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.6
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• pp.80-87
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• 1997

A series of tests was performed to determine a threshold concentration of water-soluble organic permeant(ethanol) for permeability to be increased in clay and to estimate long-term permeability behaviors, effects of overburden pressure and compaction conditions on permeability in clay. Results of study are as follows ; 1. A threshold concentration of water-soluble organic permeant(ethanol) in clay was about 7O~8O% and its dielectric constant was 40, and dielectric constant seems to be closely related with absolute permeability. 2. Permeability of long-term tests was more or less larger than that of short-term tests. 3. Overburden pressures applied for a long time elapsed have little effects on the restriction of permeability increase. 4. Since water content has no effects of compaction capability when it is compacted with OMC or wet side of OMC, its permeability is to be estimated as same level of dry side of OMC. 5. Clays matured in the humid chamber are increased in permeability 2 times larger than unmatured ones. Thixotropy, therefore, should be considered in the design procedures because field conditions of construction would be quite similar to this..

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.589-594
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• 2020

Many electronic applications require magnetic materials with high permeability and frequency properties. We improve the magnetic permeability of soft magnetic powder by controlling the shape magnetic anisotropy of the powders and through the preparation of amorphous nanoparticles. For this purpose, the effect of the shape magnetic anisotropy of amorphous Fe-B-P nanoparticles is observed through a magnetic field and the frequency characteristics and permeability of these amorphous nanoparticles are observed. These characteristics are investigated by analyzing the composition of particles, crystal structure, microstructure, magnetic properties, and permeability of particles. The composition, crystal structure, and microstructure of the particles are analyzed using inductively coupled plasma optical emission spectrometry-, X-ray diffraction, scanning electron microscopy and focused ion beam analysis. The saturation magnetization and permeability are measured using a vibrating sample magnetometer and an LCR meter, respectively. It is confirmed that the shape magnetic anisotropy of the particles influences the permeability. Finally, the permeability and frequency characteristics of the amorphous Fe-B-P nanoparticles are improved.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.188-190
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• 2001

This study presents procedures and analysis methods for well known two field soil permeability tests, disc-tension infiltrometer and Guelph permeameter. Some case tests are demonstrated and then some problems involving the tests were clarified. This study may be helpful for practical field hydrogeologists.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.181-183
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• 2002

The accurate permeability for preform is critical to model and design the impregnation of fluid resin in the composite manufacturing process. In this study, the in-plane and transverse permeability for a woven fabric are predicted numerically through the coupled flow model which combines microscopic with macroscopic flow. The microscopic and macroscopic flow which are flows within the micro-unit and macro-unit cell, respectively, are calculated by using 3-D CVFEM(control volume finite element method). To avoid checker-board pressure field and improve the efficiency on numerical computation, A new interpolation function for velocity is proposed on the basis of analytic solutions. The permeability of plain woven fabric is measured through unidirectional flow experiment and compared with the permeability calculated numerically. Based on the good agreement of the results, the relationships between the permeability and the structures of preform such as the fiber volume fraction and stacking effect can be understood. The reverse and the simple stacking are taken in account. Unlike past literatures, this study is based on more realistic unit cell and the improved prediction of permeability can be achieved. It is observed that in-plane flow is more dominant than transverse flow in the real flow through preform and the stacking effect of multi-layered preform is negligible. Consequently, the proposed coupled flow model can be applied to modeling of real composite materials processing.

• Journal of the Korean Magnetics Society
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• v.7 no.3
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• pp.159-165
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• 1997

Recently, many researchers are interested in the analysis of the magnetic fields considering the vector relation between the magnetic flux density and the magnetic field intensity. In this paper, Finite Element Method with two dimensional tensor permeability is adopted to calculate the magnetic field quantities in the system having the rotational magnetic field. In addition, the method of analyzing the magnetic field considering the harmonic components is introduced. The validity of the proposed method is proved compared with the experimental results.