• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.622-631
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• 2005

In this paper, we reduce 'over and under deviation' and 'over and under testing' which have a cause of uncertainty in electromagnetic radiated immunity test. We analyze continued measurement method of field uniformity and propose new estimate method having the minimum uncertainty condition. We test comparison in 4 anechoic chambers and analyze FDI(Field Deviation Index) which is the minimum deviation excess 6 dB on fields. We obtain that the proposed test method improve 1.193 dB than domestic standard(KN 61000-4-3) and 0.017 dB than international standard (IEC61000-4-3) in every frequency. In the test result 'over and under testing point' have 926 point at every field area and have 118 point at center uniform area. These result know that proposed measurement method have 10 point less at every field area and 9 point less at center uniform area than continued measurement method. The proposed test method have few point more than continued measurement method. Therefore, we confirmed that the proposed test method have the minimum uncertainty in electromagnetic radiated immunity test.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.751-759
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• 2008

In this study, the effect of an unsteady flow field around a body of aerostatic/aerodynamic forces were investigated using rectangular cylinders (B/D = 2, 3, 4, 5). Proper orthogonal decomposition (POD) was introduced to the analysis of the fluctuating pressure field that was measured on the stationary/oscillatory B/D=4 rectangular cylinder, and the characteristics of the proper functions with flow patterns were identified. In addition, the physical decoupling and interactions in the different co-existing flow patterns were investigated through POD. The comparison with the identified proper function associated with a particular flow pattern revealed that the Karman vortex is almost not affected by the separation bubble, but that the Karman vortex considerably interferes in the development of the separation bubble around the trailing edge. It can be considered that the Karman vortex induces the increment of the curvature of the substantial separated flow.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2459-2464
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• 2007

In present study, a temperature field of specimens which was coated with fluorescence dye such as Rhodamine-B(Rh-B) has been measured, based on the fluorescence intensity. Silica(SiO2) nano porous structure with 1um thickness was constructed on a cover glass, and fluorescence dye was digested into these porous thin films. To optimize manufacturing coating process, various solvents, Rh-B concentration, and other chemical materials were applied to fabricate the specimen and all specimens were measured on the various temperature conditions. For the measurement, a 14 bit cooled CCD camera with 1600 by 1200 spatial resolution is equipped with epifluorescence microscope to obtain only fluorescence intensity from 1.2 mm by 0.9 mm field of view of the illuminated coated specimen.

• Journal of Magnetics
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• v.21 no.3
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• pp.364-373
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• 2016

The article presents the results and findings obtained through the assembly of opposing linear Halbach arrays from two magnet layers using large magnetic blocks from permanent NdFeB magnets, especially concerning the distribution of magnetic induction in an air gap. The use of these large blocks has led to a significant expansion of the area of magnetic field with a substantially higher value of magnetic induction in comparison with similar linear Halbach arrays composed of small magnets. The paper also discusses the determined dependences of magnetic induction on the parameters of the x, y, z coordinate system and indicates the possibilities of achieving an even stronger magnetic field in a larger volume of an air gap for application for instance in equipment for magnetic separation of raw materials, in instrument technologies and in other areas.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.271-273
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• 2000

A magnetic field generator for small animal study was designed and constructed. For calculation of magnetic fields inside the cage, a three-dimensional calculation program was made. Using this, optimum electric current ratio and position of each coil were determined. Meanwhile, inductance of the generator was calculated for design of power supply. The field measurement results of the manufactured generator showed that the difference between maximum and minimum magnetic field at the living floor was less than 2%.

• Journal of the Optical Society of Korea
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• v.16 no.1
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• pp.47-52
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• 2012

The use of a $Ti:LiNbO_3$ symmetric Mach-Zehnder interferometric intensity modulator with a push-pull lumped electrode and a plate-type probe antenna to measure an electric field strength is described. The modulator has a small device size of $46{\times}7{\times}1mm$ and operates at a wavelength of $1.3{\mu}m$. The output characteristic of the interferometer shows the modulation depth of 100% and 75%, and $V_{\pi}$ voltage of 6.6 V, and 6.6 V at the 200 Hz and 1 KHz, respectively. The minimum detectable electric field is ~1.84 V/m, ~3.28 V/m, and ~11.6 V/m, corresponding to a dynamic range of about ~22 dB, ~17 dB, and ~6 dB at frequencies of 500 KHz, 1 MHz and 5 MHz, respectively.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.739-745
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• 2014

We have demonstrated a $Ti:LiNbO_3$ electro-optic electric-field sensor utilizing a $1{\times}2$ Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator, which uses a 3-dB directional coupler at the output and has two complementary output waveguides. A dc switching voltage of ~25 V and an extinction ratio of ~12.5 dB are observed at a wavelength of $1.3{\mu}m$. For a 20 dBm rf input power, the minimum detectable electric fields are ~8.21, 7.24, and ~13.3 V/m, corresponding to dynamic ranges of ~10, ~12, and ~7 dB at frequencies of 10, 30, and 50 MHz respectively. The sensors exhibit almost linear response for an applied electric-field intensity from 0.29 V/m to 29.8 V/m.

• Journal of Magnetics
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• v.19 no.3
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• pp.215-220
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• 2014

This study investigates the dynamic magneto-mechanical behavior of magnetization-graded ferromagnetic materials Terfenol-D/FeCuNbSiB (MF). We measure the dynamic magneto-mechanical properties as a function of the DC bias magnetic field ($H_{dc}$). Our experimental results show that these dynamic magneto-mechanical properties are strongly dependent on the DC bias magnetic field. Furthermore, the dynamic strain coefficient, electromechanical resonance frequency, Young's moduli, and mechanical quality factor of Terfenol-D/FeCuNbSiB are greater than those of Terfenol-D under a lower DC bias magnetic field. The dynamic strain coefficient increases by a factor of between one and three, under the same DC bias magnetic field. In particular, the dynamic strain coefficient of Terfenol-D/FeCuNbSiB at zero bias achieves 48.6 nm/A, which is about 3.05 times larger than that of Terfenol-D. These good performances indicate that magnetization-graded ferromagnetic materials show promise for application in magnetic sensors.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.236-238
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• 1990

For improving magnetic properties of the amorphous Fe-B-Si alloy, we annealed in a magnetic field oriented in the plane of the ribbon longitudinal to its long axis. By field annealing, coercive force and total core loss are reduced from 0.04 Oe to 0.02 Oe, and from 0.25 watt/kg to 0.15 watt/kg respectively comparing with non-field annealed specimen. These reductions were caused by the formation of $180^{\circ}$ domains parallel to the annealing field due to the induced anisotorpy.

• Journal of Magnetics
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• v.16 no.4
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• pp.408-412
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• 2011

We investigated theoretically the magnetic field dependence of the quantum optical transition of qusi 2-Dimensional Landau splitting system, in GaN and ZnO. We apply the Quantum Transport theory (QTR) to the system in the confinement of electrons by square well confinement potential. We use the projected Liouville equation method with Equilibrium Average Projection Scheme (EAPS). Through the analysis of this work, we found the increasing properties of the optical Quantum Transition Line Shapes(QTLSs) which show the absorption power and the Quantum Transition Line Widths(QTLWs) with the magnetic-field in GaN and ZnO. We also found that QTLW, ${\gamma}(B)_{total}$ of GaN < ${\gamma}(B)_{total}$ of ZnO in the magnetic field region B < 25 Tesla.